xref: /external/sqlite/dist/sqlite3.c

/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.6.22.  By combining all the individual C code files into this
** single large file, the entire code can be compiled as a one translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% are more are commonly seen when SQLite is compiled as a single
** translation unit.
**
** This file is all you need to compile SQLite.  To use SQLite in other
** programs, you need this file and the "sqlite3.h" header file that defines
** the programming interface to the SQLite library.  (If you do not have
** the "sqlite3.h" header file at hand, you will find a copy embedded within
** the text of this file.  Search for "Begin file sqlite3.h" to find the start
** of the embedded sqlite3.h header file.) Additional code files may be needed
** if you want a wrapper to interface SQLite with your choice of programming
** language. The code for the "sqlite3" command-line shell is also in a
** separate file. This file contains only code for the core SQLite library.
*/
#define SQLITE_CORE 1
#define SQLITE_AMALGAMATION 1
#ifndef SQLITE_PRIVATE
# define SQLITE_PRIVATE static
#endif
#ifndef SQLITE_API
# define SQLITE_API
#endif
/************** Begin file sqliteInt.h ***************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on POSIX if the
** underlying operating system supports it.  If the OS lacks
** large file support, or if the OS is windows, these should be no-ops.
**
** Ticket #2739:  The _LARGEFILE_SOURCE macro must appear before any
** system #includes.  Hence, this block of code must be the very first
** code in all source files.
**
** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
** on the compiler command line.  This is necessary if you are compiling
** on a recent machine (ex: Red Hat 7.2) but you want your code to work
** on an older machine (ex: Red Hat 6.0).  If you compile on Red Hat 7.2
** without this option, LFS is enable.  But LFS does not exist in the kernel
** in Red Hat 6.0, so the code won't work.  Hence, for maximum binary
** portability you should omit LFS.
**
** Similar is true for Mac OS X.  LFS is only supported on Mac OS X 9 and later.
*/
#ifndef SQLITE_DISABLE_LFS
# define _LARGE_FILE       1
# ifndef _FILE_OFFSET_BITS
#   define _FILE_OFFSET_BITS 64
# endif
# define _LARGEFILE_SOURCE 1
#endif

/*
** Include the configuration header output by 'configure' if we're using the
** autoconf-based build
*/
#ifdef _HAVE_SQLITE_CONFIG_H
#include "config.h"
#endif

/************** Include sqliteLimit.h in the middle of sqliteInt.h ***********/
/************** Begin file sqliteLimit.h *************************************/
/*
** 2007 May 7
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file defines various limits of what SQLite can process.
*/

/*
** The maximum length of a TEXT or BLOB in bytes.   This also
** limits the size of a row in a table or index.
**
** The hard limit is the ability of a 32-bit signed integer
** to count the size: 2^31-1 or 2147483647.
*/
#ifndef SQLITE_MAX_LENGTH
# define SQLITE_MAX_LENGTH 1000000000
#endif

/*
** This is the maximum number of
**
**    * Columns in a table
**    * Columns in an index
**    * Columns in a view
**    * Terms in the SET clause of an UPDATE statement
**    * Terms in the result set of a SELECT statement
**    * Terms in the GROUP BY or ORDER BY clauses of a SELECT statement.
**    * Terms in the VALUES clause of an INSERT statement
**
** The hard upper limit here is 32676.  Most database people will
** tell you that in a well-normalized database, you usually should
** not have more than a dozen or so columns in any table.  And if
** that is the case, there is no point in having more than a few
** dozen values in any of the other situations described above.
*/
#ifndef SQLITE_MAX_COLUMN
# define SQLITE_MAX_COLUMN 2000
#endif

/*
** The maximum length of a single SQL statement in bytes.
**
** It used to be the case that setting this value to zero would
** turn the limit off.  That is no longer true.  It is not possible
** to turn this limit off.
*/
#ifndef SQLITE_MAX_SQL_LENGTH
# define SQLITE_MAX_SQL_LENGTH 1000000000
#endif

/*
** The maximum depth of an expression tree. This is limited to
** some extent by SQLITE_MAX_SQL_LENGTH. But sometime you might
** want to place more severe limits on the complexity of an
** expression.
**
** A value of 0 used to mean that the limit was not enforced.
** But that is no longer true.  The limit is now strictly enforced
** at all times.
*/
#ifndef SQLITE_MAX_EXPR_DEPTH
# define SQLITE_MAX_EXPR_DEPTH 1000
#endif

/*
** The maximum number of terms in a compound SELECT statement.
** The code generator for compound SELECT statements does one
** level of recursion for each term.  A stack overflow can result
** if the number of terms is too large.  In practice, most SQL
** never has more than 3 or 4 terms.  Use a value of 0 to disable
** any limit on the number of terms in a compount SELECT.
*/
#ifndef SQLITE_MAX_COMPOUND_SELECT
# define SQLITE_MAX_COMPOUND_SELECT 500
#endif

/*
** The maximum number of opcodes in a VDBE program.
** Not currently enforced.
*/
#ifndef SQLITE_MAX_VDBE_OP
# define SQLITE_MAX_VDBE_OP 25000
#endif

/*
** The maximum number of arguments to an SQL function.
*/
#ifndef SQLITE_MAX_FUNCTION_ARG
# define SQLITE_MAX_FUNCTION_ARG 127
#endif

/*
** The maximum number of in-memory pages to use for the main database
** table and for temporary tables.  The SQLITE_DEFAULT_CACHE_SIZE
*/
#ifndef SQLITE_DEFAULT_CACHE_SIZE
# define SQLITE_DEFAULT_CACHE_SIZE  2000
#endif
#ifndef SQLITE_DEFAULT_TEMP_CACHE_SIZE
# define SQLITE_DEFAULT_TEMP_CACHE_SIZE  500
#endif

/*
** The maximum number of attached databases.  This must be between 0
** and 30.  The upper bound on 30 is because a 32-bit integer bitmap
** is used internally to track attached databases.
*/
#ifndef SQLITE_MAX_ATTACHED
# define SQLITE_MAX_ATTACHED 10
#endif


/*
** The maximum value of a ?nnn wildcard that the parser will accept.
*/
#ifndef SQLITE_MAX_VARIABLE_NUMBER
# define SQLITE_MAX_VARIABLE_NUMBER 999
#endif

/* Maximum page size.  The upper bound on this value is 32768.  This a limit
** imposed by the necessity of storing the value in a 2-byte unsigned integer
** and the fact that the page size must be a power of 2.
**
** If this limit is changed, then the compiled library is technically
** incompatible with an SQLite library compiled with a different limit. If
** a process operating on a database with a page-size of 65536 bytes
** crashes, then an instance of SQLite compiled with the default page-size
** limit will not be able to rollback the aborted transaction. This could
** lead to database corruption.
*/
#ifndef SQLITE_MAX_PAGE_SIZE
# define SQLITE_MAX_PAGE_SIZE 32768
#endif


/*
** The default size of a database page.
*/
#ifndef SQLITE_DEFAULT_PAGE_SIZE
# define SQLITE_DEFAULT_PAGE_SIZE 1024
#endif
#if SQLITE_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
# undef SQLITE_DEFAULT_PAGE_SIZE
# define SQLITE_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
#endif

/*
** Ordinarily, if no value is explicitly provided, SQLite creates databases
** with page size SQLITE_DEFAULT_PAGE_SIZE. However, based on certain
** device characteristics (sector-size and atomic write() support),
** SQLite may choose a larger value. This constant is the maximum value
** SQLite will choose on its own.
*/
#ifndef SQLITE_MAX_DEFAULT_PAGE_SIZE
# define SQLITE_MAX_DEFAULT_PAGE_SIZE 8192
#endif
#if SQLITE_MAX_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
# undef SQLITE_MAX_DEFAULT_PAGE_SIZE
# define SQLITE_MAX_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
#endif


/*
** Maximum number of pages in one database file.
**
** This is really just the default value for the max_page_count pragma.
** This value can be lowered (or raised) at run-time using that the
** max_page_count macro.
*/
#ifndef SQLITE_MAX_PAGE_COUNT
# define SQLITE_MAX_PAGE_COUNT 1073741823
#endif

/*
** Maximum length (in bytes) of the pattern in a LIKE or GLOB
** operator.
*/
#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
# define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000
#endif

/*
** Maximum depth of recursion for triggers.
**
** A value of 1 means that a trigger program will not be able to itself
** fire any triggers. A value of 0 means that no trigger programs at all
** may be executed.
*/
#ifndef SQLITE_MAX_TRIGGER_DEPTH
# define SQLITE_MAX_TRIGGER_DEPTH 1000
#endif

/************** End of sqliteLimit.h *****************************************/
/************** Continuing where we left off in sqliteInt.h ******************/

/* Disable nuisance warnings on Borland compilers */
#if defined(__BORLANDC__)
#pragma warn -rch /* unreachable code */
#pragma warn -ccc /* Condition is always true or false */
#pragma warn -aus /* Assigned value is never used */
#pragma warn -csu /* Comparing signed and unsigned */
#pragma warn -spa /* Suspicious pointer arithmetic */
#endif

/* Needed for various definitions... */
#ifndef _GNU_SOURCE
# define _GNU_SOURCE
#endif

/*
** Include standard header files as necessary
*/
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_INTTYPES_H
#include <inttypes.h>
#endif

#define SQLITE_INDEX_SAMPLES 10

/*
** This macro is used to "hide" some ugliness in casting an int
** value to a ptr value under the MSVC 64-bit compiler.   Casting
** non 64-bit values to ptr types results in a "hard" error with
** the MSVC 64-bit compiler which this attempts to avoid.
**
** A simple compiler pragma or casting sequence could not be found
** to correct this in all situations, so this macro was introduced.
**
** It could be argued that the intptr_t type could be used in this
** case, but that type is not available on all compilers, or
** requires the #include of specific headers which differs between
** platforms.
**
** Ticket #3860:  The llvm-gcc-4.2 compiler from Apple chokes on
** the ((void*)&((char*)0)[X]) construct.  But MSVC chokes on ((void*)(X)).
** So we have to define the macros in different ways depending on the
** compiler.
*/
#if defined(__GNUC__)
# if defined(HAVE_STDINT_H)
#   define SQLITE_INT_TO_PTR(X)  ((void*)(intptr_t)(X))
#   define SQLITE_PTR_TO_INT(X)  ((int)(intptr_t)(X))
# else
#   define SQLITE_INT_TO_PTR(X)  ((void*)(X))
#   define SQLITE_PTR_TO_INT(X)  ((int)(X))
# endif
#else
# define SQLITE_INT_TO_PTR(X)   ((void*)&((char*)0)[X])
# define SQLITE_PTR_TO_INT(X)   ((int)(((char*)X)-(char*)0))
#endif


/*
** The SQLITE_THREADSAFE macro must be defined as either 0 or 1.
** Older versions of SQLite used an optional THREADSAFE macro.
** We support that for legacy
*/
#if !defined(SQLITE_THREADSAFE)
#if defined(THREADSAFE)
# define SQLITE_THREADSAFE THREADSAFE
#else
# define SQLITE_THREADSAFE 1
#endif
#endif

/*
** The SQLITE_DEFAULT_MEMSTATUS macro must be defined as either 0 or 1.
** It determines whether or not the features related to
** SQLITE_CONFIG_MEMSTATUS are available by default or not. This value can
** be overridden at runtime using the sqlite3_config() API.
*/
#if !defined(SQLITE_DEFAULT_MEMSTATUS)
# define SQLITE_DEFAULT_MEMSTATUS 1
#endif

/*
** Exactly one of the following macros must be defined in order to
** specify which memory allocation subsystem to use.
**
**     SQLITE_SYSTEM_MALLOC          // Use normal system malloc()
**     SQLITE_MEMDEBUG               // Debugging version of system malloc()
**     SQLITE_MEMORY_SIZE            // internal allocator #1
**     SQLITE_MMAP_HEAP_SIZE         // internal mmap() allocator
**     SQLITE_POW2_MEMORY_SIZE       // internal power-of-two allocator
**
** If none of the above are defined, then set SQLITE_SYSTEM_MALLOC as
** the default.
*/
#if defined(SQLITE_SYSTEM_MALLOC)+defined(SQLITE_MEMDEBUG)+\
    defined(SQLITE_MEMORY_SIZE)+defined(SQLITE_MMAP_HEAP_SIZE)+\
    defined(SQLITE_POW2_MEMORY_SIZE)>1
# error "At most one of the following compile-time configuration options\
 is allows: SQLITE_SYSTEM_MALLOC, SQLITE_MEMDEBUG, SQLITE_MEMORY_SIZE,\
 SQLITE_MMAP_HEAP_SIZE, SQLITE_POW2_MEMORY_SIZE"
#endif
#if defined(SQLITE_SYSTEM_MALLOC)+defined(SQLITE_MEMDEBUG)+\
    defined(SQLITE_MEMORY_SIZE)+defined(SQLITE_MMAP_HEAP_SIZE)+\
    defined(SQLITE_POW2_MEMORY_SIZE)==0
# define SQLITE_SYSTEM_MALLOC 1
#endif

/*
** If SQLITE_MALLOC_SOFT_LIMIT is not zero, then try to keep the
** sizes of memory allocations below this value where possible.
*/
#if !defined(SQLITE_MALLOC_SOFT_LIMIT)
# define SQLITE_MALLOC_SOFT_LIMIT 1024
#endif

/*
** We need to define _XOPEN_SOURCE as follows in order to enable
** recursive mutexes on most Unix systems.  But Mac OS X is different.
** The _XOPEN_SOURCE define causes problems for Mac OS X we are told,
** so it is omitted there.  See ticket #2673.
**
** Later we learn that _XOPEN_SOURCE is poorly or incorrectly
** implemented on some systems.  So we avoid defining it at all
** if it is already defined or if it is unneeded because we are
** not doing a threadsafe build.  Ticket #2681.
**
** See also ticket #2741.
*/
#if !defined(_XOPEN_SOURCE) && !defined(__DARWIN__) && !defined(__APPLE__) && SQLITE_THREADSAFE
#  define _XOPEN_SOURCE 500  /* Needed to enable pthread recursive mutexes */
#endif

/*
** The TCL headers are only needed when compiling the TCL bindings.
*/
#if defined(SQLITE_TCL) || defined(TCLSH)
# include <tcl.h>
#endif

/*
** Many people are failing to set -DNDEBUG=1 when compiling SQLite.
** Setting NDEBUG makes the code smaller and run faster.  So the following
** lines are added to automatically set NDEBUG unless the -DSQLITE_DEBUG=1
** option is set.  Thus NDEBUG becomes an opt-in rather than an opt-out
** feature.
*/
#if !defined(NDEBUG) && !defined(SQLITE_DEBUG)
# define NDEBUG 1
#endif

/*
** The testcase() macro is used to aid in coverage testing.  When
** doing coverage testing, the condition inside the argument to
** testcase() must be evaluated both true and false in order to
** get full branch coverage.  The testcase() macro is inserted
** to help ensure adequate test coverage in places where simple
** condition/decision coverage is inadequate.  For example, testcase()
** can be used to make sure boundary values are tested.  For
** bitmask tests, testcase() can be used to make sure each bit
** is significant and used at least once.  On switch statements
** where multiple cases go to the same block of code, testcase()
** can insure that all cases are evaluated.
**
*/
#ifdef SQLITE_COVERAGE_TEST
SQLITE_PRIVATE   void sqlite3Coverage(int);
# define testcase(X)  if( X ){ sqlite3Coverage(__LINE__); }
#else
# define testcase(X)
#endif

/*
** The TESTONLY macro is used to enclose variable declarations or
** other bits of code that are needed to support the arguments
** within testcase() and assert() macros.
*/
#if !defined(NDEBUG) || defined(SQLITE_COVERAGE_TEST)
# define TESTONLY(X)  X
#else
# define TESTONLY(X)
#endif

/*
** Sometimes we need a small amount of code such as a variable initialization
** to setup for a later assert() statement.  We do not want this code to
** appear when assert() is disabled.  The following macro is therefore
** used to contain that setup code.  The "VVA" acronym stands for
** "Verification, Validation, and Accreditation".  In other words, the
** code within VVA_ONLY() will only run during verification processes.
*/
#ifndef NDEBUG
# define VVA_ONLY(X)  X
#else
# define VVA_ONLY(X)
#endif

/*
** The ALWAYS and NEVER macros surround boolean expressions which
** are intended to always be true or false, respectively.  Such
** expressions could be omitted from the code completely.  But they
** are included in a few cases in order to enhance the resilience
** of SQLite to unexpected behavior - to make the code "self-healing"
** or "ductile" rather than being "brittle" and crashing at the first
** hint of unplanned behavior.
**
** In other words, ALWAYS and NEVER are added for defensive code.
**
** When doing coverage testing ALWAYS and NEVER are hard-coded to
** be true and false so that the unreachable code then specify will
** not be counted as untested code.
*/
#if defined(SQLITE_COVERAGE_TEST)
# define ALWAYS(X)      (1)
# define NEVER(X)       (0)
#elif !defined(NDEBUG)
# define ALWAYS(X)      ((X)?1:(assert(0),0))
# define NEVER(X)       ((X)?(assert(0),1):0)
#else
# define ALWAYS(X)      (X)
# define NEVER(X)       (X)
#endif

/*
** The macro unlikely() is a hint that surrounds a boolean
** expression that is usually false.  Macro likely() surrounds
** a boolean expression that is usually true.  GCC is able to
** use these hints to generate better code, sometimes.
*/
#if defined(__GNUC__) && 0
# define likely(X)    __builtin_expect((X),1)
# define unlikely(X)  __builtin_expect((X),0)
#else
# define likely(X)    !!(X)
# define unlikely(X)  !!(X)
#endif

/************** Include sqlite3.h in the middle of sqliteInt.h ***************/
/************** Begin file sqlite3.h *****************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the SQLite library
** presents to client programs.  If a C-function, structure, datatype,
** or constant definition does not appear in this file, then it is
** not a published API of SQLite, is subject to change without
** notice, and should not be referenced by programs that use SQLite.
**
** Some of the definitions that are in this file are marked as
** "experimental".  Experimental interfaces are normally new
** features recently added to SQLite.  We do not anticipate changes
** to experimental interfaces but reserve the right to make minor changes
** if experience from use "in the wild" suggest such changes are prudent.
**
** The official C-language API documentation for SQLite is derived
** from comments in this file.  This file is the authoritative source
** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
*/
#if 0
extern "C" {
#endif


/*
** Add the ability to override 'extern'
*/
#ifndef SQLITE_EXTERN
# define SQLITE_EXTERN extern
#endif

#ifndef SQLITE_API
# define SQLITE_API
#endif


/*
** These no-op macros are used in front of interfaces to mark those
** interfaces as either deprecated or experimental.  New applications
** should not use deprecated interfaces - they are support for backwards
** compatibility only.  Application writers should be aware that
** experimental interfaces are subject to change in point releases.
**
** These macros used to resolve to various kinds of compiler magic that
** would generate warning messages when they were used.  But that
** compiler magic ended up generating such a flurry of bug reports
** that we have taken it all out and gone back to using simple
** noop macros.
*/
#define SQLITE_DEPRECATED
#define SQLITE_EXPERIMENTAL

/*
** Ensure these symbols were not defined by some previous header file.
*/
#ifdef SQLITE_VERSION
# undef SQLITE_VERSION
#endif
#ifdef SQLITE_VERSION_NUMBER
# undef SQLITE_VERSION_NUMBER
#endif

/*
** CAPI3REF: Compile-Time Library Version Numbers
**
** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
** evaluates to a string literal that is the SQLite version in the
** format "X.Y.Z" where X is the major version number (always 3 for
** SQLite3) and Y is the minor version number and Z is the release number.)^
** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
** numbers used in [SQLITE_VERSION].)^
** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
** be larger than the release from which it is derived.  Either Y will
** be held constant and Z will be incremented or else Y will be incremented
** and Z will be reset to zero.
**
** Since version 3.6.18, SQLite source code has been stored in the
** <a href="http://www.fossil-scm.org/">Fossil configuration management
** system</a>.  ^The SQLITE_SOURCE_ID macro evalutes to
** a string which identifies a particular check-in of SQLite
** within its configuration management system.  ^The SQLITE_SOURCE_ID
** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.6.22"
#define SQLITE_VERSION_NUMBER 3006022
#define SQLITE_SOURCE_ID      "2010-03-22 23:55:10 82dd61fccff3e4c77e060e5734cd4b4e2eeb7c32"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
** but are associated with the library instead of the header file.  ^(Cautious
** programmers might include assert() statements in their application to
** verify that values returned by these interfaces match the macros in
** the header, and thus insure that the application is
** compiled with matching library and header files.
**
** <blockquote><pre>
** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
** </pre></blockquote>)^
**
** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
** macro.  ^The sqlite3_libversion() function returns a pointer to the
** to the sqlite3_version[] string constant.  The sqlite3_libversion()
** function is provided for use in DLLs since DLL users usually do not have
** direct access to string constants within the DLL.  ^The
** sqlite3_libversion_number() function returns an integer equal to
** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function a pointer
** to a string constant whose value is the same as the [SQLITE_SOURCE_ID]
** C preprocessor macro.
**
** See also: [sqlite_version()] and [sqlite_source_id()].
*/
SQLITE_API const char sqlite3_version[] = SQLITE_VERSION;
SQLITE_API const char *sqlite3_libversion(void);
SQLITE_API const char *sqlite3_sourceid(void);
SQLITE_API int sqlite3_libversion_number(void);

/*
** CAPI3REF: Test To See If The Library Is Threadsafe
**
** ^The sqlite3_threadsafe() function returns zero if and only if
** SQLite was compiled mutexing code omitted due to the
** [SQLITE_THREADSAFE] compile-time option being set to 0.
**
** SQLite can be compiled with or without mutexes.  When
** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
** are enabled and SQLite is threadsafe.  When the
** [SQLITE_THREADSAFE] macro is 0,
** the mutexes are omitted.  Without the mutexes, it is not safe
** to use SQLite concurrently from more than one thread.
**
** Enabling mutexes incurs a measurable performance penalty.
** So if speed is of utmost importance, it makes sense to disable
** the mutexes.  But for maximum safety, mutexes should be enabled.
** ^The default behavior is for mutexes to be enabled.
**
** This interface can be used by an application to make sure that the
** version of SQLite that it is linking against was compiled with
** the desired setting of the [SQLITE_THREADSAFE] macro.
**
** This interface only reports on the compile-time mutex setting
** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
** can be fully or partially disabled using a call to [sqlite3_config()]
** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
** or [SQLITE_CONFIG_MUTEX].  ^(The return value of the
** sqlite3_threadsafe() function shows only the compile-time setting of
** thread safety, not any run-time changes to that setting made by
** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
** is unchanged by calls to sqlite3_config().)^
**
** See the [threading mode] documentation for additional information.
*/
SQLITE_API int sqlite3_threadsafe(void);

/*
** CAPI3REF: Database Connection Handle
** KEYWORDS: {database connection} {database connections}
**
** Each open SQLite database is represented by a pointer to an instance of
** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
** is its destructor.  There are many other interfaces (such as
** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
** [sqlite3_busy_timeout()] to name but three) that are methods on an
** sqlite3 object.
*/
typedef struct sqlite3 sqlite3;

/*
** CAPI3REF: 64-Bit Integer Types
** KEYWORDS: sqlite_int64 sqlite_uint64
**
** Because there is no cross-platform way to specify 64-bit integer types
** SQLite includes typedefs for 64-bit signed and unsigned integers.
**
** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
** The sqlite_int64 and sqlite_uint64 types are supported for backwards
** compatibility only.
**
** ^The sqlite3_int64 and sqlite_int64 types can store integer values
** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
** sqlite3_uint64 and sqlite_uint64 types can store integer values
** between 0 and +18446744073709551615 inclusive.
*/
#ifdef SQLITE_INT64_TYPE
  typedef SQLITE_INT64_TYPE sqlite_int64;
  typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
#elif defined(_MSC_VER) || defined(__BORLANDC__)
  typedef __int64 sqlite_int64;
  typedef unsigned __int64 sqlite_uint64;
#else
  typedef long long int sqlite_int64;
  typedef unsigned long long int sqlite_uint64;
#endif
typedef sqlite_int64 sqlite3_int64;
typedef sqlite_uint64 sqlite3_uint64;

/*
** If compiling for a processor that lacks floating point support,
** substitute integer for floating-point.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# define double sqlite3_int64
#endif

/*
** CAPI3REF: Closing A Database Connection
**
** ^The sqlite3_close() routine is the destructor for the [sqlite3] object.
** ^Calls to sqlite3_close() return SQLITE_OK if the [sqlite3] object is
** successfullly destroyed and all associated resources are deallocated.
**
** Applications must [sqlite3_finalize | finalize] all [prepared statements]
** and [sqlite3_blob_close | close] all [BLOB handles] associated with
** the [sqlite3] object prior to attempting to close the object.  ^If
** sqlite3_close() is called on a [database connection] that still has
** outstanding [prepared statements] or [BLOB handles], then it returns
** SQLITE_BUSY.
**
** ^If [sqlite3_close()] is invoked while a transaction is open,
** the transaction is automatically rolled back.
**
** The C parameter to [sqlite3_close(C)] must be either a NULL
** pointer or an [sqlite3] object pointer obtained
** from [sqlite3_open()], [sqlite3_open16()], or
** [sqlite3_open_v2()], and not previously closed.
** ^Calling sqlite3_close() with a NULL pointer argument is a
** harmless no-op.
*/
SQLITE_API int sqlite3_close(sqlite3 *);

/*
** The type for a callback function.
** This is legacy and deprecated.  It is included for historical
** compatibility and is not documented.
*/
typedef int (*sqlite3_callback)(void*,int,char**, char**);

/*
** CAPI3REF: One-Step Query Execution Interface
**
** The sqlite3_exec() interface is a convenience wrapper around
** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
** that allows an application to run multiple statements of SQL
** without having to use a lot of C code.
**
** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
** semicolon-separate SQL statements passed into its 2nd argument,
** in the context of the [database connection] passed in as its 1st
** argument.  ^If the callback function of the 3rd argument to
** sqlite3_exec() is not NULL, then it is invoked for each result row
** coming out of the evaluated SQL statements.  ^The 4th argument to
** to sqlite3_exec() is relayed through to the 1st argument of each
** callback invocation.  ^If the callback pointer to sqlite3_exec()
** is NULL, then no callback is ever invoked and result rows are
** ignored.
**
** ^If an error occurs while evaluating the SQL statements passed into
** sqlite3_exec(), then execution of the current statement stops and
** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
** is not NULL then any error message is written into memory obtained
** from [sqlite3_malloc()] and passed back through the 5th parameter.
** To avoid memory leaks, the application should invoke [sqlite3_free()]
** on error message strings returned through the 5th parameter of
** of sqlite3_exec() after the error message string is no longer needed.
** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
** NULL before returning.
**
** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
** routine returns SQLITE_ABORT without invoking the callback again and
** without running any subsequent SQL statements.
**
** ^The 2nd argument to the sqlite3_exec() callback function is the
** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
** callback is an array of pointers to strings obtained as if from
** [sqlite3_column_text()], one for each column.  ^If an element of a
** result row is NULL then the corresponding string pointer for the
** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
** sqlite3_exec() callback is an array of pointers to strings where each
** entry represents the name of corresponding result column as obtained
** from [sqlite3_column_name()].
**
** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
** to an empty string, or a pointer that contains only whitespace and/or
** SQL comments, then no SQL statements are evaluated and the database
** is not changed.
**
** Restrictions:
**
** <ul>
** <li> The application must insure that the 1st parameter to sqlite3_exec()
**      is a valid and open [database connection].
** <li> The application must not close [database connection] specified by
**      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
** <li> The application must not modify the SQL statement text passed into
**      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
** </ul>
*/
SQLITE_API int sqlite3_exec(
  sqlite3*,                                  /* An open database */
  const char *sql,                           /* SQL to be evaluated */
  int (*callback)(void*,int,char**,char**),  /* Callback function */
  void *,                                    /* 1st argument to callback */
  char **errmsg                              /* Error msg written here */
);

/*
** CAPI3REF: Result Codes
** KEYWORDS: SQLITE_OK {error code} {error codes}
** KEYWORDS: {result code} {result codes}
**
** Many SQLite functions return an integer result code from the set shown
** here in order to indicates success or failure.
**
** New error codes may be added in future versions of SQLite.
**
** See also: [SQLITE_IOERR_READ | extended result codes]
*/
#define SQLITE_OK           0   /* Successful result */
/* beginning-of-error-codes */
#define SQLITE_ERROR        1   /* SQL error or missing database */
#define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
#define SQLITE_PERM         3   /* Access permission denied */
#define SQLITE_ABORT        4   /* Callback routine requested an abort */
#define SQLITE_BUSY         5   /* The database file is locked */
#define SQLITE_LOCKED       6   /* A table in the database is locked */
#define SQLITE_NOMEM        7   /* A malloc() failed */
#define SQLITE_READONLY     8   /* Attempt to write a readonly database */
#define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
#define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
#define SQLITE_CORRUPT     11   /* The database disk image is malformed */
#define SQLITE_NOTFOUND    12   /* NOT USED. Table or record not found */
#define SQLITE_FULL        13   /* Insertion failed because database is full */
#define SQLITE_CANTOPEN    14   /* Unable to open the database file */
#define SQLITE_PROTOCOL    15   /* NOT USED. Database lock protocol error */
#define SQLITE_EMPTY       16   /* Database is empty */
#define SQLITE_SCHEMA      17   /* The database schema changed */
#define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
#define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
#define SQLITE_MISMATCH    20   /* Data type mismatch */
#define SQLITE_MISUSE      21   /* Library used incorrectly */
#define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
#define SQLITE_AUTH        23   /* Authorization denied */
#define SQLITE_FORMAT      24   /* Auxiliary database format error */
#define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
#define SQLITE_NOTADB      26   /* File opened that is not a database file */
#define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
#define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
/* end-of-error-codes */

/*
** CAPI3REF: Extended Result Codes
** KEYWORDS: {extended error code} {extended error codes}
** KEYWORDS: {extended result code} {extended result codes}
**
** In its default configuration, SQLite API routines return one of 26 integer
** [SQLITE_OK | result codes].  However, experience has shown that many of
** these result codes are too coarse-grained.  They do not provide as
** much information about problems as programmers might like.  In an effort to
** address this, newer versions of SQLite (version 3.3.8 and later) include
** support for additional result codes that provide more detailed information
** about errors. The extended result codes are enabled or disabled
** on a per database connection basis using the
** [sqlite3_extended_result_codes()] API.
**
** Some of the available extended result codes are listed here.
** One may expect the number of extended result codes will be expand
** over time.  Software that uses extended result codes should expect
** to see new result codes in future releases of SQLite.
**
** The SQLITE_OK result code will never be extended.  It will always
** be exactly zero.
*/
#define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
#define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
#define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
#define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
#define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
#define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
#define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
#define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
#define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
#define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
#define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
#define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
#define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
#define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
#define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
#define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED | (1<<8) )

/*
** CAPI3REF: Flags For File Open Operations
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the xOpen method of the
** [sqlite3_vfs] object.
*/
#define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
#define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
#define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
#define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
#define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
#define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
#define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
#define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
#define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */

/*
** CAPI3REF: Device Characteristics
**
** The xDeviceCapabilities method of the [sqlite3_io_methods]
** object returns an integer which is a vector of the these
** bit values expressing I/O characteristics of the mass storage
** device that holds the file that the [sqlite3_io_methods]
** refers to.
**
** The SQLITE_IOCAP_ATOMIC property means that all writes of
** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
** mean that writes of blocks that are nnn bytes in size and
** are aligned to an address which is an integer multiple of
** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
** that when data is appended to a file, the data is appended
** first then the size of the file is extended, never the other
** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
** information is written to disk in the same order as calls
** to xWrite().
*/
#define SQLITE_IOCAP_ATOMIC          0x00000001
#define SQLITE_IOCAP_ATOMIC512       0x00000002
#define SQLITE_IOCAP_ATOMIC1K        0x00000004
#define SQLITE_IOCAP_ATOMIC2K        0x00000008
#define SQLITE_IOCAP_ATOMIC4K        0x00000010
#define SQLITE_IOCAP_ATOMIC8K        0x00000020
#define SQLITE_IOCAP_ATOMIC16K       0x00000040
#define SQLITE_IOCAP_ATOMIC32K       0x00000080
#define SQLITE_IOCAP_ATOMIC64K       0x00000100
#define SQLITE_IOCAP_SAFE_APPEND     0x00000200
#define SQLITE_IOCAP_SEQUENTIAL      0x00000400

/*
** CAPI3REF: File Locking Levels
**
** SQLite uses one of these integer values as the second
** argument to calls it makes to the xLock() and xUnlock() methods
** of an [sqlite3_io_methods] object.
*/
#define SQLITE_LOCK_NONE          0
#define SQLITE_LOCK_SHARED        1
#define SQLITE_LOCK_RESERVED      2
#define SQLITE_LOCK_PENDING       3
#define SQLITE_LOCK_EXCLUSIVE     4

/*
** CAPI3REF: Synchronization Type Flags
**
** When SQLite invokes the xSync() method of an
** [sqlite3_io_methods] object it uses a combination of
** these integer values as the second argument.
**
** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
** sync operation only needs to flush data to mass storage.  Inode
** information need not be flushed. If the lower four bits of the flag
** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
** If the lower four bits equal SQLITE_SYNC_FULL, that means
** to use Mac OS X style fullsync instead of fsync().
*/
#define SQLITE_SYNC_NORMAL        0x00002
#define SQLITE_SYNC_FULL          0x00003
#define SQLITE_SYNC_DATAONLY      0x00010

/*
** CAPI3REF: OS Interface Open File Handle
**
** An [sqlite3_file] object represents an open file in the
** [sqlite3_vfs | OS interface layer].  Individual OS interface
** implementations will
** want to subclass this object by appending additional fields
** for their own use.  The pMethods entry is a pointer to an
** [sqlite3_io_methods] object that defines methods for performing
** I/O operations on the open file.
*/
typedef struct sqlite3_file sqlite3_file;
struct sqlite3_file {
  const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
};

/*
** CAPI3REF: OS Interface File Virtual Methods Object
**
** Every file opened by the [sqlite3_vfs] xOpen method populates an
** [sqlite3_file] object (or, more commonly, a subclass of the
** [sqlite3_file] object) with a pointer to an instance of this object.
** This object defines the methods used to perform various operations
** against the open file represented by the [sqlite3_file] object.
**
** If the xOpen method sets the sqlite3_file.pMethods element
** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
** may be invoked even if the xOpen reported that it failed.  The
** only way to prevent a call to xClose following a failed xOpen
** is for the xOpen to set the sqlite3_file.pMethods element to NULL.
**
** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
** flag may be ORed in to indicate that only the data of the file
** and not its inode needs to be synced.
**
** The integer values to xLock() and xUnlock() are one of
** <ul>
** <li> [SQLITE_LOCK_NONE],
** <li> [SQLITE_LOCK_SHARED],
** <li> [SQLITE_LOCK_RESERVED],
** <li> [SQLITE_LOCK_PENDING], or
** <li> [SQLITE_LOCK_EXCLUSIVE].
** </ul>
** xLock() increases the lock. xUnlock() decreases the lock.
** The xCheckReservedLock() method checks whether any database connection,
** either in this process or in some other process, is holding a RESERVED,
** PENDING, or EXCLUSIVE lock on the file.  It returns true
** if such a lock exists and false otherwise.
**
** The xFileControl() method is a generic interface that allows custom
** VFS implementations to directly control an open file using the
** [sqlite3_file_control()] interface.  The second "op" argument is an
** integer opcode.  The third argument is a generic pointer intended to
** point to a structure that may contain arguments or space in which to
** write return values.  Potential uses for xFileControl() might be
** functions to enable blocking locks with timeouts, to change the
** locking strategy (for example to use dot-file locks), to inquire
** about the status of a lock, or to break stale locks.  The SQLite
** core reserves all opcodes less than 100 for its own use.
** A [SQLITE_FCNTL_LOCKSTATE | list of opcodes] less than 100 is available.
** Applications that define a custom xFileControl method should use opcodes
** greater than 100 to avoid conflicts.
**
** The xSectorSize() method returns the sector size of the
** device that underlies the file.  The sector size is the
** minimum write that can be performed without disturbing
** other bytes in the file.  The xDeviceCharacteristics()
** method returns a bit vector describing behaviors of the
** underlying device:
**
** <ul>
** <li> [SQLITE_IOCAP_ATOMIC]
** <li> [SQLITE_IOCAP_ATOMIC512]
** <li> [SQLITE_IOCAP_ATOMIC1K]
** <li> [SQLITE_IOCAP_ATOMIC2K]
** <li> [SQLITE_IOCAP_ATOMIC4K]
** <li> [SQLITE_IOCAP_ATOMIC8K]
** <li> [SQLITE_IOCAP_ATOMIC16K]
** <li> [SQLITE_IOCAP_ATOMIC32K]
** <li> [SQLITE_IOCAP_ATOMIC64K]
** <li> [SQLITE_IOCAP_SAFE_APPEND]
** <li> [SQLITE_IOCAP_SEQUENTIAL]
** </ul>
**
** The SQLITE_IOCAP_ATOMIC property means that all writes of
** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
** mean that writes of blocks that are nnn bytes in size and
** are aligned to an address which is an integer multiple of
** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
** that when data is appended to a file, the data is appended
** first then the size of the file is extended, never the other
** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
** information is written to disk in the same order as calls
** to xWrite().
**
** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
** in the unread portions of the buffer with zeros.  A VFS that
** fails to zero-fill short reads might seem to work.  However,
** failure to zero-fill short reads will eventually lead to
** database corruption.
*/
typedef struct sqlite3_io_methods sqlite3_io_methods;
struct sqlite3_io_methods {
  int iVersion;
  int (*xClose)(sqlite3_file*);
  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
  int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
  int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
  int (*xSync)(sqlite3_file*, int flags);
  int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
  int (*xLock)(sqlite3_file*, int);
  int (*xUnlock)(sqlite3_file*, int);
  int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
  int (*xFileControl)(sqlite3_file*, int op, void *pArg);
  int (*xSectorSize)(sqlite3_file*);
  int (*xDeviceCharacteristics)(sqlite3_file*);
  /* Additional methods may be added in future releases */
};

/*
** CAPI3REF: Standard File Control Opcodes
**
** These integer constants are opcodes for the xFileControl method
** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
** interface.
**
** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
** opcode causes the xFileControl method to write the current state of
** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
** into an integer that the pArg argument points to. This capability
** is used during testing and only needs to be supported when SQLITE_TEST
** is defined.
*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4

/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only
** deals with pointers to the [sqlite3_mutex] object.
**
** Mutexes are created using [sqlite3_mutex_alloc()].
*/
typedef struct sqlite3_mutex sqlite3_mutex;

/*
** CAPI3REF: OS Interface Object
**
** An instance of the sqlite3_vfs object defines the interface between
** the SQLite core and the underlying operating system.  The "vfs"
** in the name of the object stands for "virtual file system".
**
** The value of the iVersion field is initially 1 but may be larger in
** future versions of SQLite.  Additional fields may be appended to this
** object when the iVersion value is increased.  Note that the structure
** of the sqlite3_vfs object changes in the transaction between
** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
** modified.
**
** The szOsFile field is the size of the subclassed [sqlite3_file]
** structure used by this VFS.  mxPathname is the maximum length of
** a pathname in this VFS.
**
** Registered sqlite3_vfs objects are kept on a linked list formed by
** the pNext pointer.  The [sqlite3_vfs_register()]
** and [sqlite3_vfs_unregister()] interfaces manage this list
** in a thread-safe way.  The [sqlite3_vfs_find()] interface
** searches the list.  Neither the application code nor the VFS
** implementation should use the pNext pointer.
**
** The pNext field is the only field in the sqlite3_vfs
** structure that SQLite will ever modify.  SQLite will only access
** or modify this field while holding a particular static mutex.
** The application should never modify anything within the sqlite3_vfs
** object once the object has been registered.
**
** The zName field holds the name of the VFS module.  The name must
** be unique across all VFS modules.
**
** SQLite will guarantee that the zFilename parameter to xOpen
** is either a NULL pointer or string obtained
** from xFullPathname().  SQLite further guarantees that
** the string will be valid and unchanged until xClose() is
** called. Because of the previous sentence,
** the [sqlite3_file] can safely store a pointer to the
** filename if it needs to remember the filename for some reason.
** If the zFilename parameter is xOpen is a NULL pointer then xOpen
** must invent its own temporary name for the file.  Whenever the
** xFilename parameter is NULL it will also be the case that the
** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
**
** The flags argument to xOpen() includes all bits set in
** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
** or [sqlite3_open16()] is used, then flags includes at least
** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE].
** If xOpen() opens a file read-only then it sets *pOutFlags to
** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
**
** SQLite will also add one of the following flags to the xOpen()
** call, depending on the object being opened:
**
** <ul>
** <li>  [SQLITE_OPEN_MAIN_DB]
** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
** <li>  [SQLITE_OPEN_TEMP_DB]
** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
** <li>  [SQLITE_OPEN_TRANSIENT_DB]
** <li>  [SQLITE_OPEN_SUBJOURNAL]
** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
** </ul>
**
** The file I/O implementation can use the object type flags to
** change the way it deals with files.  For example, an application
** that does not care about crash recovery or rollback might make
** the open of a journal file a no-op.  Writes to this journal would
** also be no-ops, and any attempt to read the journal would return
** SQLITE_IOERR.  Or the implementation might recognize that a database
** file will be doing page-aligned sector reads and writes in a random
** order and set up its I/O subsystem accordingly.
**
** SQLite might also add one of the following flags to the xOpen method:
**
** <ul>
** <li> [SQLITE_OPEN_DELETEONCLOSE]
** <li> [SQLITE_OPEN_EXCLUSIVE]
** </ul>
**
** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
** deleted when it is closed.  The [SQLITE_OPEN_DELETEONCLOSE]
** will be set for TEMP  databases, journals and for subjournals.
**
** The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
** with the [SQLITE_OPEN_CREATE] flag, which are both directly
** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the
** SQLITE_OPEN_CREATE, is used to indicate that file should always
** be created, and that it is an error if it already exists.
** It is <i>not</i> used to indicate the file should be opened
** for exclusive access.
**
** At least szOsFile bytes of memory are allocated by SQLite
** to hold the  [sqlite3_file] structure passed as the third
** argument to xOpen.  The xOpen method does not have to
** allocate the structure; it should just fill it in.  Note that
** the xOpen method must set the sqlite3_file.pMethods to either
** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
** element will be valid after xOpen returns regardless of the success
** or failure of the xOpen call.
**
** The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
** to test whether a file is at least readable.   The file can be a
** directory.
**
** SQLite will always allocate at least mxPathname+1 bytes for the
** output buffer xFullPathname.  The exact size of the output buffer
** is also passed as a parameter to both  methods. If the output buffer
** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
** handled as a fatal error by SQLite, vfs implementations should endeavor
** to prevent this by setting mxPathname to a sufficiently large value.
**
** The xRandomness(), xSleep(), and xCurrentTime() interfaces
** are not strictly a part of the filesystem, but they are
** included in the VFS structure for completeness.
** The xRandomness() function attempts to return nBytes bytes
** of good-quality randomness into zOut.  The return value is
** the actual number of bytes of randomness obtained.
** The xSleep() method causes the calling thread to sleep for at
** least the number of microseconds given.  The xCurrentTime()
** method returns a Julian Day Number for the current date and time.
**
*/
typedef struct sqlite3_vfs sqlite3_vfs;
struct sqlite3_vfs {
  int iVersion;            /* Structure version number */
  int szOsFile;            /* Size of subclassed sqlite3_file */
  int mxPathname;          /* Maximum file pathname length */
  sqlite3_vfs *pNext;      /* Next registered VFS */
  const char *zName;       /* Name of this virtual file system */
  void *pAppData;          /* Pointer to application-specific data */
  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
               int flags, int *pOutFlags);
  int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
  int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
  int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
  void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
  void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
  void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
  void (*xDlClose)(sqlite3_vfs*, void*);
  int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
  int (*xSleep)(sqlite3_vfs*, int microseconds);
  int (*xCurrentTime)(sqlite3_vfs*, double*);
  int (*xGetLastError)(sqlite3_vfs*, int, char *);
  /* New fields may be appended in figure versions.  The iVersion
  ** value will increment whenever this happens. */
};

/*
** CAPI3REF: Flags for the xAccess VFS method
**
** These integer constants can be used as the third parameter to
** the xAccess method of an [sqlite3_vfs] object.  They determine
** what kind of permissions the xAccess method is looking for.
** With SQLITE_ACCESS_EXISTS, the xAccess method
** simply checks whether the file exists.
** With SQLITE_ACCESS_READWRITE, the xAccess method
** checks whether the file is both readable and writable.
** With SQLITE_ACCESS_READ, the xAccess method
** checks whether the file is readable.
*/
#define SQLITE_ACCESS_EXISTS    0
#define SQLITE_ACCESS_READWRITE 1
#define SQLITE_ACCESS_READ      2

/*
** CAPI3REF: Initialize The SQLite Library
**
** ^The sqlite3_initialize() routine initializes the
** SQLite library.  ^The sqlite3_shutdown() routine
** deallocates any resources that were allocated by sqlite3_initialize().
** These routines are designed to aid in process initialization and
** shutdown on embedded systems.  Workstation applications using
** SQLite normally do not need to invoke either of these routines.
**
** A call to sqlite3_initialize() is an "effective" call if it is
** the first time sqlite3_initialize() is invoked during the lifetime of
** the process, or if it is the first time sqlite3_initialize() is invoked
** following a call to sqlite3_shutdown().  ^(Only an effective call
** of sqlite3_initialize() does any initialization.  All other calls
** are harmless no-ops.)^
**
** A call to sqlite3_shutdown() is an "effective" call if it is the first
** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
** an effective call to sqlite3_shutdown() does any deinitialization.
** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
**
** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
** is not.  The sqlite3_shutdown() interface must only be called from a
** single thread.  All open [database connections] must be closed and all
** other SQLite resources must be deallocated prior to invoking
** sqlite3_shutdown().
**
** Among other things, ^sqlite3_initialize() will invoke
** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
** will invoke sqlite3_os_end().
**
** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
** ^If for some reason, sqlite3_initialize() is unable to initialize
** the library (perhaps it is unable to allocate a needed resource such
** as a mutex) it returns an [error code] other than [SQLITE_OK].
**
** ^The sqlite3_initialize() routine is called internally by many other
** SQLite interfaces so that an application usually does not need to
** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
** calls sqlite3_initialize() so the SQLite library will be automatically
** initialized when [sqlite3_open()] is called if it has not be initialized
** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
** compile-time option, then the automatic calls to sqlite3_initialize()
** are omitted and the application must call sqlite3_initialize() directly
** prior to using any other SQLite interface.  For maximum portability,
** it is recommended that applications always invoke sqlite3_initialize()
** directly prior to using any other SQLite interface.  Future releases
** of SQLite may require this.  In other words, the behavior exhibited
** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
** default behavior in some future release of SQLite.
**
** The sqlite3_os_init() routine does operating-system specific
** initialization of the SQLite library.  The sqlite3_os_end()
** routine undoes the effect of sqlite3_os_init().  Typical tasks
** performed by these routines include allocation or deallocation
** of static resources, initialization of global variables,
** setting up a default [sqlite3_vfs] module, or setting up
** a default configuration using [sqlite3_config()].
**
** The application should never invoke either sqlite3_os_init()
** or sqlite3_os_end() directly.  The application should only invoke
** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
** interface is called automatically by sqlite3_initialize() and
** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
** implementations for sqlite3_os_init() and sqlite3_os_end()
** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
** When [custom builds | built for other platforms]
** (using the [SQLITE_OS_OTHER=1] compile-time
** option) the application must supply a suitable implementation for
** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
** implementation of sqlite3_os_init() or sqlite3_os_end()
** must return [SQLITE_OK] on success and some other [error code] upon
** failure.
*/
SQLITE_API int sqlite3_initialize(void);
SQLITE_API int sqlite3_shutdown(void);
SQLITE_API int sqlite3_os_init(void);
SQLITE_API int sqlite3_os_end(void);

/*
** CAPI3REF: Configuring The SQLite Library
**
** The sqlite3_config() interface is used to make global configuration
** changes to SQLite in order to tune SQLite to the specific needs of
** the application.  The default configuration is recommended for most
** applications and so this routine is usually not necessary.  It is
** provided to support rare applications with unusual needs.
**
** The sqlite3_config() interface is not threadsafe.  The application
** must insure that no other SQLite interfaces are invoked by other
** threads while sqlite3_config() is running.  Furthermore, sqlite3_config()
** may only be invoked prior to library initialization using
** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
** Note, however, that ^sqlite3_config() can be called as part of the
** implementation of an application-defined [sqlite3_os_init()].
**
** The first argument to sqlite3_config() is an integer
** [SQLITE_CONFIG_SINGLETHREAD | configuration option] that determines
** what property of SQLite is to be configured.  Subsequent arguments
** vary depending on the [SQLITE_CONFIG_SINGLETHREAD | configuration option]
** in the first argument.
**
** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
** ^If the option is unknown or SQLite is unable to set the option
** then this routine returns a non-zero [error code].
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_config(int, ...);

/*
** CAPI3REF: Configure database connections
** EXPERIMENTAL
**
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection].  The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).  The
** sqlite3_db_config() interface should only be used immediately after
** the database connection is created using [sqlite3_open()],
** [sqlite3_open16()], or [sqlite3_open_v2()].
**
** The second argument to sqlite3_db_config(D,V,...)  is the
** configuration verb - an integer code that indicates what
** aspect of the [database connection] is being configured.
** The only choice for this value is [SQLITE_DBCONFIG_LOOKASIDE].
** New verbs are likely to be added in future releases of SQLite.
** Additional arguments depend on the verb.
**
** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
** the call is considered successful.
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_db_config(sqlite3*, int op, ...);

/*
** CAPI3REF: Memory Allocation Routines
** EXPERIMENTAL
**
** An instance of this object defines the interface between SQLite
** and low-level memory allocation routines.
**
** This object is used in only one place in the SQLite interface.
** A pointer to an instance of this object is the argument to
** [sqlite3_config()] when the configuration option is
** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].
** By creating an instance of this object
** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
** during configuration, an application can specify an alternative
** memory allocation subsystem for SQLite to use for all of its
** dynamic memory needs.
**
** Note that SQLite comes with several [built-in memory allocators]
** that are perfectly adequate for the overwhelming majority of applications
** and that this object is only useful to a tiny minority of applications
** with specialized memory allocation requirements.  This object is
** also used during testing of SQLite in order to specify an alternative
** memory allocator that simulates memory out-of-memory conditions in
** order to verify that SQLite recovers gracefully from such
** conditions.
**
** The xMalloc and xFree methods must work like the
** malloc() and free() functions from the standard C library.
** The xRealloc method must work like realloc() from the standard C library
** with the exception that if the second argument to xRealloc is zero,
** xRealloc must be a no-op - it must not perform any allocation or
** deallocation.  ^SQLite guarantees that the second argument to
** xRealloc is always a value returned by a prior call to xRoundup.
** And so in cases where xRoundup always returns a positive number,
** xRealloc can perform exactly as the standard library realloc() and
** still be in compliance with this specification.
**
** xSize should return the allocated size of a memory allocation
** previously obtained from xMalloc or xRealloc.  The allocated size
** is always at least as big as the requested size but may be larger.
**
** The xRoundup method returns what would be the allocated size of
** a memory allocation given a particular requested size.  Most memory
** allocators round up memory allocations at least to the next multiple
** of 8.  Some allocators round up to a larger multiple or to a power of 2.
** Every memory allocation request coming in through [sqlite3_malloc()]
** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0,
** that causes the corresponding memory allocation to fail.
**
** The xInit method initializes the memory allocator.  (For example,
** it might allocate any require mutexes or initialize internal data
** structures.  The xShutdown method is invoked (indirectly) by
** [sqlite3_shutdown()] and should deallocate any resources acquired
** by xInit.  The pAppData pointer is used as the only parameter to
** xInit and xShutdown.
**
** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
** the xInit method, so the xInit method need not be threadsafe.  The
** xShutdown method is only called from [sqlite3_shutdown()] so it does
** not need to be threadsafe either.  For all other methods, SQLite
** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
** it is by default) and so the methods are automatically serialized.
** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
** methods must be threadsafe or else make their own arrangements for
** serialization.
**
** SQLite will never invoke xInit() more than once without an intervening
** call to xShutdown().
*/
typedef struct sqlite3_mem_methods sqlite3_mem_methods;
struct sqlite3_mem_methods {
  void *(*xMalloc)(int);         /* Memory allocation function */
  void (*xFree)(void*);          /* Free a prior allocation */
  void *(*xRealloc)(void*,int);  /* Resize an allocation */
  int (*xSize)(void*);           /* Return the size of an allocation */
  int (*xRoundup)(int);          /* Round up request size to allocation size */
  int (*xInit)(void*);           /* Initialize the memory allocator */
  void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  void *pAppData;                /* Argument to xInit() and xShutdown() */
};

/*
** CAPI3REF: Configuration Options
** EXPERIMENTAL
**
** These constants are the available integer configuration options that
** can be passed as the first argument to the [sqlite3_config()] interface.
**
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued.  Applications
** should check the return code from [sqlite3_config()] to make sure that
** the call worked.  The [sqlite3_config()] interface will return a
** non-zero [error code] if a discontinued or unsupported configuration option
** is invoked.
**
** <dl>
** <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
** <dd>There are no arguments to this option.  ^This option sets the
** [threading mode] to Single-thread.  In other words, it disables
** all mutexing and puts SQLite into a mode where it can only be used
** by a single thread.   ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** it is not possible to change the [threading mode] from its default
** value of Single-thread and so [sqlite3_config()] will return
** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
** configuration option.</dd>
**
** <dt>SQLITE_CONFIG_MULTITHREAD</dt>
** <dd>There are no arguments to this option.  ^This option sets the
** [threading mode] to Multi-thread.  In other words, it disables
** mutexing on [database connection] and [prepared statement] objects.
** The application is responsible for serializing access to
** [database connections] and [prepared statements].  But other mutexes
** are enabled so that SQLite will be safe to use in a multi-threaded
** environment as long as no two threads attempt to use the same
** [database connection] at the same time.  ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** it is not possible to set the Multi-thread [threading mode] and
** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
**
** <dt>SQLITE_CONFIG_SERIALIZED</dt>
** <dd>There are no arguments to this option.  ^This option sets the
** [threading mode] to Serialized. In other words, this option enables
** all mutexes including the recursive
** mutexes on [database connection] and [prepared statement] objects.
** In this mode (which is the default when SQLite is compiled with
** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
** to [database connections] and [prepared statements] so that the
** application is free to use the same [database connection] or the
** same [prepared statement] in different threads at the same time.
** ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** it is not possible to set the Serialized [threading mode] and
** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
**
** <dt>SQLITE_CONFIG_MALLOC</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mem_methods] structure.  The argument specifies
** alternative low-level memory allocation routines to be used in place of
** the memory allocation routines built into SQLite.)^ ^SQLite makes
** its own private copy of the content of the [sqlite3_mem_methods] structure
** before the [sqlite3_config()] call returns.</dd>
**
** <dt>SQLITE_CONFIG_GETMALLOC</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mem_methods] structure.  The [sqlite3_mem_methods]
** structure is filled with the currently defined memory allocation routines.)^
** This option can be used to overload the default memory allocation
** routines with a wrapper that simulations memory allocation failure or
** tracks memory usage, for example. </dd>
**
** <dt>SQLITE_CONFIG_MEMSTATUS</dt>
** <dd> ^This option takes single argument of type int, interpreted as a
** boolean, which enables or disables the collection of memory allocation
** statistics. ^(When memory allocation statistics are disabled, the
** following SQLite interfaces become non-operational:
**   <ul>
**   <li> [sqlite3_memory_used()]
**   <li> [sqlite3_memory_highwater()]
**   <li> [sqlite3_soft_heap_limit()]
**   <li> [sqlite3_status()]
**   </ul>)^
** ^Memory allocation statistics are enabled by default unless SQLite is
** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
** allocation statistics are disabled by default.
** </dd>
**
** <dt>SQLITE_CONFIG_SCRATCH</dt>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** scratch memory.  There are three arguments:  A pointer an 8-byte
** aligned memory buffer from which the scrach allocations will be
** drawn, the size of each scratch allocation (sz),
** and the maximum number of scratch allocations (N).  The sz
** argument must be a multiple of 16. The sz parameter should be a few bytes
** larger than the actual scratch space required due to internal overhead.
** The first argument must be a pointer to an 8-byte aligned buffer
** of at least sz*N bytes of memory.
** ^SQLite will use no more than one scratch buffer per thread.  So
** N should be set to the expected maximum number of threads.  ^SQLite will
** never require a scratch buffer that is more than 6 times the database
** page size. ^If SQLite needs needs additional scratch memory beyond
** what is provided by this configuration option, then
** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
**
** <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** the database page cache with the default page cache implemenation.
** This configuration should not be used if an application-define page
** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
** There are three arguments to this option: A pointer to 8-byte aligned
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument should be the size of the largest database page
** (a power of two between 512 and 32768) plus a little extra for each
** page header.  ^The page header size is 20 to 40 bytes depending on
** the host architecture.  ^It is harmless, apart from the wasted memory,
** to make sz a little too large.  The first
** argument should point to an allocation of at least sz*N bytes of memory.
** ^SQLite will use the memory provided by the first argument to satisfy its
** memory needs for the first N pages that it adds to cache.  ^If additional
** page cache memory is needed beyond what is provided by this option, then
** SQLite goes to [sqlite3_malloc()] for the additional storage space.
** ^The implementation might use one or more of the N buffers to hold
** memory accounting information. The pointer in the first argument must
** be aligned to an 8-byte boundary or subsequent behavior of SQLite
** will be undefined.</dd>
**
** <dt>SQLITE_CONFIG_HEAP</dt>
** <dd> ^This option specifies a static memory buffer that SQLite will use
** for all of its dynamic memory allocation needs beyond those provided
** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
** There are three arguments: An 8-byte aligned pointer to the memory,
** the number of bytes in the memory buffer, and the minimum allocation size.
** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.
** The first pointer (the memory pointer) must be aligned to an 8-byte
** boundary or subsequent behavior of SQLite will be undefined.</dd>
**
** <dt>SQLITE_CONFIG_MUTEX</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
** alternative low-level mutex routines to be used in place
** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
** content of the [sqlite3_mutex_methods] structure before the call to
** [sqlite3_config()] returns. ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** the entire mutexing subsystem is omitted from the build and hence calls to
** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
** return [SQLITE_ERROR].</dd>
**
** <dt>SQLITE_CONFIG_GETMUTEX</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The
** [sqlite3_mutex_methods]
** structure is filled with the currently defined mutex routines.)^
** This option can be used to overload the default mutex allocation
** routines with a wrapper used to track mutex usage for performance
** profiling or testing, for example.   ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** the entire mutexing subsystem is omitted from the build and hence calls to
** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
** return [SQLITE_ERROR].</dd>
**
** <dt>SQLITE_CONFIG_LOOKASIDE</dt>
** <dd> ^(This option takes two arguments that determine the default
** memory allocation for the lookaside memory allocator on each
** [database connection].  The first argument is the
** size of each lookaside buffer slot and the second is the number of
** slots allocated to each database connection.)^  ^(This option sets the
** <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
** verb to [sqlite3_db_config()] can be used to change the lookaside
** configuration on individual connections.)^ </dd>
**
** <dt>SQLITE_CONFIG_PCACHE</dt>
** <dd> ^(This option takes a single argument which is a pointer to
** an [sqlite3_pcache_methods] object.  This object specifies the interface
** to a custom page cache implementation.)^  ^SQLite makes a copy of the
** object and uses it for page cache memory allocations.</dd>
**
** <dt>SQLITE_CONFIG_GETPCACHE</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** [sqlite3_pcache_methods] object.  SQLite copies of the current
** page cache implementation into that object.)^ </dd>
**
** </dl>
*/
#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */
#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
#define SQLITE_CONFIG_PCACHE       14  /* sqlite3_pcache_methods* */
#define SQLITE_CONFIG_GETPCACHE    15  /* sqlite3_pcache_methods* */
#define SQLITE_CONFIG_LOG          16  /* xFunc, void* */

/*
** CAPI3REF: Configuration Options
** EXPERIMENTAL
**
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.
**
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued.  Applications
** should check the return code from [sqlite3_db_config()] to make sure that
** the call worked.  ^The [sqlite3_db_config()] interface will return a
** non-zero [error code] if a discontinued or unsupported configuration option
** is invoked.
**
** <dl>
** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
** <dd> ^This option takes three additional arguments that determine the
** [lookaside memory allocator] configuration for the [database connection].
** ^The first argument (the third parameter to [sqlite3_db_config()] is a
** pointer to an memory buffer to use for lookaside memory.
** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
** may be NULL in which case SQLite will allocate the
** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
** size of each lookaside buffer slot.  ^The third argument is the number of
** slots.  The size of the buffer in the first argument must be greater than
** or equal to the product of the second and third arguments.  The buffer
** must be aligned to an 8-byte boundary.  ^If the second argument to
** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
** rounded down to the next smaller
** multiple of 8.  See also: [SQLITE_CONFIG_LOOKASIDE]</dd>
**
** </dl>
*/
#define SQLITE_DBCONFIG_LOOKASIDE    1001  /* void* int int */


/*
** CAPI3REF: Enable Or Disable Extended Result Codes
**
** ^The sqlite3_extended_result_codes() routine enables or disables the
** [extended result codes] feature of SQLite. ^The extended result
** codes are disabled by default for historical compatibility.
*/
SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);

/*
** CAPI3REF: Last Insert Rowid
**
** ^Each entry in an SQLite table has a unique 64-bit signed
** integer key called the [ROWID | "rowid"]. ^The rowid is always available
** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
** names are not also used by explicitly declared columns. ^If
** the table has a column of type [INTEGER PRIMARY KEY] then that column
** is another alias for the rowid.
**
** ^This routine returns the [rowid] of the most recent
** successful [INSERT] into the database from the [database connection]
** in the first argument.  ^If no successful [INSERT]s
** have ever occurred on that database connection, zero is returned.
**
** ^(If an [INSERT] occurs within a trigger, then the [rowid] of the inserted
** row is returned by this routine as long as the trigger is running.
** But once the trigger terminates, the value returned by this routine
** reverts to the last value inserted before the trigger fired.)^
**
** ^An [INSERT] that fails due to a constraint violation is not a
** successful [INSERT] and does not change the value returned by this
** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
** and INSERT OR ABORT make no changes to the return value of this
** routine when their insertion fails.  ^(When INSERT OR REPLACE
** encounters a constraint violation, it does not fail.  The
** INSERT continues to completion after deleting rows that caused
** the constraint problem so INSERT OR REPLACE will always change
** the return value of this interface.)^
**
** ^For the purposes of this routine, an [INSERT] is considered to
** be successful even if it is subsequently rolled back.
**
** This function is accessible to SQL statements via the
** [last_insert_rowid() SQL function].
**
** If a separate thread performs a new [INSERT] on the same
** database connection while the [sqlite3_last_insert_rowid()]
** function is running and thus changes the last insert [rowid],
** then the value returned by [sqlite3_last_insert_rowid()] is
** unpredictable and might not equal either the old or the new
** last insert [rowid].
*/
SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);

/*
** CAPI3REF: Count The Number Of Rows Modified
**
** ^This function returns the number of database rows that were changed
** or inserted or deleted by the most recently completed SQL statement
** on the [database connection] specified by the first parameter.
** ^(Only changes that are directly specified by the [INSERT], [UPDATE],
** or [DELETE] statement are counted.  Auxiliary changes caused by
** triggers or [foreign key actions] are not counted.)^ Use the
** [sqlite3_total_changes()] function to find the total number of changes
** including changes caused by triggers and foreign key actions.
**
** ^Changes to a view that are simulated by an [INSTEAD OF trigger]
** are not counted.  Only real table changes are counted.
**
** ^(A "row change" is a change to a single row of a single table
** caused by an INSERT, DELETE, or UPDATE statement.  Rows that
** are changed as side effects of [REPLACE] constraint resolution,
** rollback, ABORT processing, [DROP TABLE], or by any other
** mechanisms do not count as direct row changes.)^
**
** A "trigger context" is a scope of execution that begins and
** ends with the script of a [CREATE TRIGGER | trigger].
** Most SQL statements are
** evaluated outside of any trigger.  This is the "top level"
** trigger context.  If a trigger fires from the top level, a
** new trigger context is entered for the duration of that one
** trigger.  Subtriggers create subcontexts for their duration.
**
** ^Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
** not create a new trigger context.
**
** ^This function returns the number of direct row changes in the
** most recent INSERT, UPDATE, or DELETE statement within the same
** trigger context.
**
** ^Thus, when called from the top level, this function returns the
** number of changes in the most recent INSERT, UPDATE, or DELETE
** that also occurred at the top level.  ^(Within the body of a trigger,
** the sqlite3_changes() interface can be called to find the number of
** changes in the most recently completed INSERT, UPDATE, or DELETE
** statement within the body of the same trigger.
** However, the number returned does not include changes
** caused by subtriggers since those have their own context.)^
**
** See also the [sqlite3_total_changes()] interface, the
** [count_changes pragma], and the [changes() SQL function].
**
** If a separate thread makes changes on the same database connection
** while [sqlite3_changes()] is running then the value returned
** is unpredictable and not meaningful.
*/
SQLITE_API int sqlite3_changes(sqlite3*);

/*
** CAPI3REF: Total Number Of Rows Modified
**
** ^This function returns the number of row changes caused by [INSERT],
** [UPDATE] or [DELETE] statements since the [database connection] was opened.
** ^(The count returned by sqlite3_total_changes() includes all changes
** from all [CREATE TRIGGER | trigger] contexts and changes made by
** [foreign key actions]. However,
** the count does not include changes used to implement [REPLACE] constraints,
** do rollbacks or ABORT processing, or [DROP TABLE] processing.  The
** count does not include rows of views that fire an [INSTEAD OF trigger],
** though if the INSTEAD OF trigger makes changes of its own, those changes
** are counted.)^
** ^The sqlite3_total_changes() function counts the changes as soon as
** the statement that makes them is completed (when the statement handle
** is passed to [sqlite3_reset()] or [sqlite3_finalize()]).
**
** See also the [sqlite3_changes()] interface, the
** [count_changes pragma], and the [total_changes() SQL function].
**
** If a separate thread makes changes on the same database connection
** while [sqlite3_total_changes()] is running then the value
** returned is unpredictable and not meaningful.
*/
SQLITE_API int sqlite3_total_changes(sqlite3*);

/*
** CAPI3REF: Interrupt A Long-Running Query
**
** ^This function causes any pending database operation to abort and
** return at its earliest opportunity. This routine is typically
** called in response to a user action such as pressing "Cancel"
** or Ctrl-C where the user wants a long query operation to halt
** immediately.
**
** ^It is safe to call this routine from a thread different from the
** thread that is currently running the database operation.  But it
** is not safe to call this routine with a [database connection] that
** is closed or might close before sqlite3_interrupt() returns.
**
** ^If an SQL operation is very nearly finished at the time when
** sqlite3_interrupt() is called, then it might not have an opportunity
** to be interrupted and might continue to completion.
**
** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
** that is inside an explicit transaction, then the entire transaction
** will be rolled back automatically.
**
** ^The sqlite3_interrupt(D) call is in effect until all currently running
** SQL statements on [database connection] D complete.  ^Any new SQL statements
** that are started after the sqlite3_interrupt() call and before the
** running statements reaches zero are interrupted as if they had been
** running prior to the sqlite3_interrupt() call.  ^New SQL statements
** that are started after the running statement count reaches zero are
** not effected by the sqlite3_interrupt().
** ^A call to sqlite3_interrupt(D) that occurs when there are no running
** SQL statements is a no-op and has no effect on SQL statements
** that are started after the sqlite3_interrupt() call returns.
**
** If the database connection closes while [sqlite3_interrupt()]
** is running then bad things will likely happen.
*/
SQLITE_API void sqlite3_interrupt(sqlite3*);

/*
** CAPI3REF: Determine If An SQL Statement Is Complete
**
** These routines are useful during command-line input to determine if the
** currently entered text seems to form a complete SQL statement or
** if additional input is needed before sending the text into
** SQLite for parsing.  ^These routines return 1 if the input string
** appears to be a complete SQL statement.  ^A statement is judged to be
** complete if it ends with a semicolon token and is not a prefix of a
** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
** string literals or quoted identifier names or comments are not
** independent tokens (they are part of the token in which they are
** embedded) and thus do not count as a statement terminator.  ^Whitespace
** and comments that follow the final semicolon are ignored.
**
** ^These routines return 0 if the statement is incomplete.  ^If a
** memory allocation fails, then SQLITE_NOMEM is returned.
**
** ^These routines do not parse the SQL statements thus
** will not detect syntactically incorrect SQL.
**
** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior
** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
** automatically by sqlite3_complete16().  If that initialization fails,
** then the return value from sqlite3_complete16() will be non-zero
** regardless of whether or not the input SQL is complete.)^
**
** The input to [sqlite3_complete()] must be a zero-terminated
** UTF-8 string.
**
** The input to [sqlite3_complete16()] must be a zero-terminated
** UTF-16 string in native byte order.
*/
SQLITE_API int sqlite3_complete(const char *sql);
SQLITE_API int sqlite3_complete16(const void *sql);

/*
** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
**
** ^This routine sets a callback function that might be invoked whenever
** an attempt is made to open a database table that another thread
** or process has locked.
**
** ^If the busy callback is NULL, then [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED]
** is returned immediately upon encountering the lock.  ^If the busy callback
** is not NULL, then the callback might be invoked with two arguments.
**
** ^The first argument to the busy handler is a copy of the void* pointer which
** is the third argument to sqlite3_busy_handler().  ^The second argument to
** the busy handler callback is the number of times that the busy handler has
** been invoked for this locking event.  ^If the
** busy callback returns 0, then no additional attempts are made to
** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
** ^If the callback returns non-zero, then another attempt
** is made to open the database for reading and the cycle repeats.
**
** The presence of a busy handler does not guarantee that it will be invoked
** when there is lock contention. ^If SQLite determines that invoking the busy
** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
** or [SQLITE_IOERR_BLOCKED] instead of invoking the busy handler.
** Consider a scenario where one process is holding a read lock that
** it is trying to promote to a reserved lock and
** a second process is holding a reserved lock that it is trying
** to promote to an exclusive lock.  The first process cannot proceed
** because it is blocked by the second and the second process cannot
** proceed because it is blocked by the first.  If both processes
** invoke the busy handlers, neither will make any progress.  Therefore,
** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
** will induce the first process to release its read lock and allow
** the second process to proceed.
**
** ^The default busy callback is NULL.
**
** ^The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
** when SQLite is in the middle of a large transaction where all the
** changes will not fit into the in-memory cache.  SQLite will
** already hold a RESERVED lock on the database file, but it needs
** to promote this lock to EXCLUSIVE so that it can spill cache
** pages into the database file without harm to concurrent
** readers.  ^If it is unable to promote the lock, then the in-memory
** cache will be left in an inconsistent state and so the error
** code is promoted from the relatively benign [SQLITE_BUSY] to
** the more severe [SQLITE_IOERR_BLOCKED].  ^This error code promotion
** forces an automatic rollback of the changes.  See the
** <a href="/cvstrac/wiki?p=CorruptionFollowingBusyError">
** CorruptionFollowingBusyError</a> wiki page for a discussion of why
** this is important.
**
** ^(There can only be a single busy handler defined for each
** [database connection].  Setting a new busy handler clears any
** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
** will also set or clear the busy handler.
**
** The busy callback should not take any actions which modify the
** database connection that invoked the busy handler.  Any such actions
** result in undefined behavior.
**
** A busy handler must not close the database connection
** or [prepared statement] that invoked the busy handler.
*/
SQLITE_API int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);

/*
** CAPI3REF: Set A Busy Timeout
**
** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
** for a specified amount of time when a table is locked.  ^The handler
** will sleep multiple times until at least "ms" milliseconds of sleeping
** have accumulated.  ^After at least "ms" milliseconds of sleeping,
** the handler returns 0 which causes [sqlite3_step()] to return
** [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED].
**
** ^Calling this routine with an argument less than or equal to zero
** turns off all busy handlers.
**
** ^(There can only be a single busy handler for a particular
** [database connection] any any given moment.  If another busy handler
** was defined  (using [sqlite3_busy_handler()]) prior to calling
** this routine, that other busy handler is cleared.)^
*/
SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);

/*
** CAPI3REF: Convenience Routines For Running Queries
**
** Definition: A <b>result table</b> is memory data structure created by the
** [sqlite3_get_table()] interface.  A result table records the
** complete query results from one or more queries.
**
** The table conceptually has a number of rows and columns.  But
** these numbers are not part of the result table itself.  These
** numbers are obtained separately.  Let N be the number of rows
** and M be the number of columns.
**
** A result table is an array of pointers to zero-terminated UTF-8 strings.
** There are (N+1)*M elements in the array.  The first M pointers point
** to zero-terminated strings that  contain the names of the columns.
** The remaining entries all point to query results.  NULL values result
** in NULL pointers.  All other values are in their UTF-8 zero-terminated
** string representation as returned by [sqlite3_column_text()].
**
** A result table might consist of one or more memory allocations.
** It is not safe to pass a result table directly to [sqlite3_free()].
** A result table should be deallocated using [sqlite3_free_table()].
**
** As an example of the result table format, suppose a query result
** is as follows:
**
** <blockquote><pre>
**        Name        | Age
**        -----------------------
**        Alice       | 43
**        Bob         | 28
**        Cindy       | 21
** </pre></blockquote>
**
** There are two column (M==2) and three rows (N==3).  Thus the
** result table has 8 entries.  Suppose the result table is stored
** in an array names azResult.  Then azResult holds this content:
**
** <blockquote><pre>
**        azResult&#91;0] = "Name";
**        azResult&#91;1] = "Age";
**        azResult&#91;2] = "Alice";
**        azResult&#91;3] = "43";
**        azResult&#91;4] = "Bob";
**        azResult&#91;5] = "28";
**        azResult&#91;6] = "Cindy";
**        azResult&#91;7] = "21";
** </pre></blockquote>
**
** ^The sqlite3_get_table() function evaluates one or more
** semicolon-separated SQL statements in the zero-terminated UTF-8
** string of its 2nd parameter and returns a result table to the
** pointer given in its 3rd parameter.
**
** After the application has finished with the result from sqlite3_get_table(),
** it should pass the result table pointer to sqlite3_free_table() in order to
** release the memory that was malloced.  Because of the way the
** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
** function must not try to call [sqlite3_free()] directly.  Only
** [sqlite3_free_table()] is able to release the memory properly and safely.
**
** ^(The sqlite3_get_table() interface is implemented as a wrapper around
** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
** to any internal data structures of SQLite.  It uses only the public
** interface defined here.  As a consequence, errors that occur in the
** wrapper layer outside of the internal [sqlite3_exec()] call are not
** reflected in subsequent calls to [sqlite3_errcode()] or
** [sqlite3_errmsg()].)^
*/
SQLITE_API int sqlite3_get_table(
  sqlite3 *db,          /* An open database */
  const char *zSql,     /* SQL to be evaluated */
  char ***pazResult,    /* Results of the query */
  int *pnRow,           /* Number of result rows written here */
  int *pnColumn,        /* Number of result columns written here */
  char **pzErrmsg       /* Error msg written here */
);
SQLITE_API void sqlite3_free_table(char **result);

/*
** CAPI3REF: Formatted String Printing Functions
**
** These routines are work-alikes of the "printf()" family of functions
** from the standard C library.
**
** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
** results into memory obtained from [sqlite3_malloc()].
** The strings returned by these two routines should be
** released by [sqlite3_free()].  ^Both routines return a
** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
** memory to hold the resulting string.
**
** ^(In sqlite3_snprintf() routine is similar to "snprintf()" from
** the standard C library.  The result is written into the
** buffer supplied as the second parameter whose size is given by
** the first parameter. Note that the order of the
** first two parameters is reversed from snprintf().)^  This is an
** historical accident that cannot be fixed without breaking
** backwards compatibility.  ^(Note also that sqlite3_snprintf()
** returns a pointer to its buffer instead of the number of
** characters actually written into the buffer.)^  We admit that
** the number of characters written would be a more useful return
** value but we cannot change the implementation of sqlite3_snprintf()
** now without breaking compatibility.
**
** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
** guarantees that the buffer is always zero-terminated.  ^The first
** parameter "n" is the total size of the buffer, including space for
** the zero terminator.  So the longest string that can be completely
** written will be n-1 characters.
**
** These routines all implement some additional formatting
** options that are useful for constructing SQL statements.
** All of the usual printf() formatting options apply.  In addition, there
** is are "%q", "%Q", and "%z" options.
**
** ^(The %q option works like %s in that it substitutes a null-terminated
** string from the argument list.  But %q also doubles every '\'' character.
** %q is designed for use inside a string literal.)^  By doubling each '\''
** character it escapes that character and allows it to be inserted into
** the string.
**
** For example, assume the string variable zText contains text as follows:
**
** <blockquote><pre>
**  char *zText = "It's a happy day!";
** </pre></blockquote>
**
** One can use this text in an SQL statement as follows:
**
** <blockquote><pre>
**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
**  sqlite3_exec(db, zSQL, 0, 0, 0);
**  sqlite3_free(zSQL);
** </pre></blockquote>
**
** Because the %q format string is used, the '\'' character in zText
** is escaped and the SQL generated is as follows:
**
** <blockquote><pre>
**  INSERT INTO table1 VALUES('It''s a happy day!')
** </pre></blockquote>
**
** This is correct.  Had we used %s instead of %q, the generated SQL
** would have looked like this:
**
** <blockquote><pre>
**  INSERT INTO table1 VALUES('It's a happy day!');
** </pre></blockquote>
**
** This second example is an SQL syntax error.  As a general rule you should
** always use %q instead of %s when inserting text into a string literal.
**
** ^(The %Q option works like %q except it also adds single quotes around
** the outside of the total string.  Additionally, if the parameter in the
** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
** single quotes).)^  So, for example, one could say:
**
** <blockquote><pre>
**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
**  sqlite3_exec(db, zSQL, 0, 0, 0);
**  sqlite3_free(zSQL);
** </pre></blockquote>
**
** The code above will render a correct SQL statement in the zSQL
** variable even if the zText variable is a NULL pointer.
**
** ^(The "%z" formatting option works like "%s" but with the
** addition that after the string has been read and copied into
** the result, [sqlite3_free()] is called on the input string.)^
*/
SQLITE_API char *sqlite3_mprintf(const char*,...);
SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);

/*
** CAPI3REF: Memory Allocation Subsystem
**
** The SQLite core uses these three routines for all of its own
** internal memory allocation needs. "Core" in the previous sentence
** does not include operating-system specific VFS implementation.  The
** Windows VFS uses native malloc() and free() for some operations.
**
** ^The sqlite3_malloc() routine returns a pointer to a block
** of memory at least N bytes in length, where N is the parameter.
** ^If sqlite3_malloc() is unable to obtain sufficient free
** memory, it returns a NULL pointer.  ^If the parameter N to
** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
** a NULL pointer.
**
** ^Calling sqlite3_free() with a pointer previously returned
** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
** that it might be reused.  ^The sqlite3_free() routine is
** a no-op if is called with a NULL pointer.  Passing a NULL pointer
** to sqlite3_free() is harmless.  After being freed, memory
** should neither be read nor written.  Even reading previously freed
** memory might result in a segmentation fault or other severe error.
** Memory corruption, a segmentation fault, or other severe error
** might result if sqlite3_free() is called with a non-NULL pointer that
** was not obtained from sqlite3_malloc() or sqlite3_realloc().
**
** ^(The sqlite3_realloc() interface attempts to resize a
** prior memory allocation to be at least N bytes, where N is the
** second parameter.  The memory allocation to be resized is the first
** parameter.)^ ^ If the first parameter to sqlite3_realloc()
** is a NULL pointer then its behavior is identical to calling
** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
** ^If the second parameter to sqlite3_realloc() is zero or
** negative then the behavior is exactly the same as calling
** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
** ^sqlite3_realloc() returns a pointer to a memory allocation
** of at least N bytes in size or NULL if sufficient memory is unavailable.
** ^If M is the size of the prior allocation, then min(N,M) bytes
** of the prior allocation are copied into the beginning of buffer returned
** by sqlite3_realloc() and the prior allocation is freed.
** ^If sqlite3_realloc() returns NULL, then the prior allocation
** is not freed.
**
** ^The memory returned by sqlite3_malloc() and sqlite3_realloc()
** is always aligned to at least an 8 byte boundary.
**
** In SQLite version 3.5.0 and 3.5.1, it was possible to define
** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
** implementation of these routines to be omitted.  That capability
** is no longer provided.  Only built-in memory allocators can be used.
**
** The Windows OS interface layer calls
** the system malloc() and free() directly when converting
** filenames between the UTF-8 encoding used by SQLite
** and whatever filename encoding is used by the particular Windows
** installation.  Memory allocation errors are detected, but
** they are reported back as [SQLITE_CANTOPEN] or
** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
**
** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
** must be either NULL or else pointers obtained from a prior
** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
** not yet been released.
**
** The application must not read or write any part of
** a block of memory after it has been released using
** [sqlite3_free()] or [sqlite3_realloc()].
*/
SQLITE_API void *sqlite3_malloc(int);
SQLITE_API void *sqlite3_realloc(void*, int);
SQLITE_API void sqlite3_free(void*);

/*
** CAPI3REF: Memory Allocator Statistics
**
** SQLite provides these two interfaces for reporting on the status
** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
** routines, which form the built-in memory allocation subsystem.
**
** ^The [sqlite3_memory_used()] routine returns the number of bytes
** of memory currently outstanding (malloced but not freed).
** ^The [sqlite3_memory_highwater()] routine returns the maximum
** value of [sqlite3_memory_used()] since the high-water mark
** was last reset.  ^The values returned by [sqlite3_memory_used()] and
** [sqlite3_memory_highwater()] include any overhead
** added by SQLite in its implementation of [sqlite3_malloc()],
** but not overhead added by the any underlying system library
** routines that [sqlite3_malloc()] may call.
**
** ^The memory high-water mark is reset to the current value of
** [sqlite3_memory_used()] if and only if the parameter to
** [sqlite3_memory_highwater()] is true.  ^The value returned
** by [sqlite3_memory_highwater(1)] is the high-water mark
** prior to the reset.
*/
SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);

/*
** CAPI3REF: Pseudo-Random Number Generator
**
** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
** select random [ROWID | ROWIDs] when inserting new records into a table that
** already uses the largest possible [ROWID].  The PRNG is also used for
** the build-in random() and randomblob() SQL functions.  This interface allows
** applications to access the same PRNG for other purposes.
**
** ^A call to this routine stores N bytes of randomness into buffer P.
**
** ^The first time this routine is invoked (either internally or by
** the application) the PRNG is seeded using randomness obtained
** from the xRandomness method of the default [sqlite3_vfs] object.
** ^On all subsequent invocations, the pseudo-randomness is generated
** internally and without recourse to the [sqlite3_vfs] xRandomness
** method.
*/
SQLITE_API void sqlite3_randomness(int N, void *P);

/*
** CAPI3REF: Compile-Time Authorization Callbacks
**
** ^This routine registers a authorizer callback with a particular
** [database connection], supplied in the first argument.
** ^The authorizer callback is invoked as SQL statements are being compiled
** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
** points during the compilation process, as logic is being created
** to perform various actions, the authorizer callback is invoked to
** see if those actions are allowed.  ^The authorizer callback should
** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
** specific action but allow the SQL statement to continue to be
** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
** rejected with an error.  ^If the authorizer callback returns
** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
** then the [sqlite3_prepare_v2()] or equivalent call that triggered
** the authorizer will fail with an error message.
**
** When the callback returns [SQLITE_OK], that means the operation
** requested is ok.  ^When the callback returns [SQLITE_DENY], the
** [sqlite3_prepare_v2()] or equivalent call that triggered the
** authorizer will fail with an error message explaining that
** access is denied.
**
** ^The first parameter to the authorizer callback is a copy of the third
** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
** to the callback is an integer [SQLITE_COPY | action code] that specifies
** the particular action to be authorized. ^The third through sixth parameters
** to the callback are zero-terminated strings that contain additional
** details about the action to be authorized.
**
** ^If the action code is [SQLITE_READ]
** and the callback returns [SQLITE_IGNORE] then the
** [prepared statement] statement is constructed to substitute
** a NULL value in place of the table column that would have
** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
** return can be used to deny an untrusted user access to individual
** columns of a table.
** ^If the action code is [SQLITE_DELETE] and the callback returns
** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
** [truncate optimization] is disabled and all rows are deleted individually.
**
** An authorizer is used when [sqlite3_prepare | preparing]
** SQL statements from an untrusted source, to ensure that the SQL statements
** do not try to access data they are not allowed to see, or that they do not
** try to execute malicious statements that damage the database.  For
** example, an application may allow a user to enter arbitrary
** SQL queries for evaluation by a database.  But the application does
** not want the user to be able to make arbitrary changes to the
** database.  An authorizer could then be put in place while the
** user-entered SQL is being [sqlite3_prepare | prepared] that
** disallows everything except [SELECT] statements.
**
** Applications that need to process SQL from untrusted sources
** might also consider lowering resource limits using [sqlite3_limit()]
** and limiting database size using the [max_page_count] [PRAGMA]
** in addition to using an authorizer.
**
** ^(Only a single authorizer can be in place on a database connection
** at a time.  Each call to sqlite3_set_authorizer overrides the
** previous call.)^  ^Disable the authorizer by installing a NULL callback.
** The authorizer is disabled by default.
**
** The authorizer callback must not do anything that will modify
** the database connection that invoked the authorizer callback.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
** statement might be re-prepared during [sqlite3_step()] due to a
** schema change.  Hence, the application should ensure that the
** correct authorizer callback remains in place during the [sqlite3_step()].
**
** ^Note that the authorizer callback is invoked only during
** [sqlite3_prepare()] or its variants.  Authorization is not
** performed during statement evaluation in [sqlite3_step()], unless
** as stated in the previous paragraph, sqlite3_step() invokes
** sqlite3_prepare_v2() to reprepare a statement after a schema change.
*/
SQLITE_API int sqlite3_set_authorizer(
  sqlite3*,
  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  void *pUserData
);

/*
** CAPI3REF: Authorizer Return Codes
**
** The [sqlite3_set_authorizer | authorizer callback function] must
** return either [SQLITE_OK] or one of these two constants in order
** to signal SQLite whether or not the action is permitted.  See the
** [sqlite3_set_authorizer | authorizer documentation] for additional
** information.
*/
#define SQLITE_DENY   1   /* Abort the SQL statement with an error */
#define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */

/*
** CAPI3REF: Authorizer Action Codes
**
** The [sqlite3_set_authorizer()] interface registers a callback function
** that is invoked to authorize certain SQL statement actions.  The
** second parameter to the callback is an integer code that specifies
** what action is being authorized.  These are the integer action codes that
** the authorizer callback may be passed.
**
** These action code values signify what kind of operation is to be
** authorized.  The 3rd and 4th parameters to the authorization
** callback function will be parameters or NULL depending on which of these
** codes is used as the second parameter.  ^(The 5th parameter to the
** authorizer callback is the name of the database ("main", "temp",
** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
** is the name of the inner-most trigger or view that is responsible for
** the access attempt or NULL if this access attempt is directly from
** top-level SQL code.
*/
/******************************************* 3rd ************ 4th ***********/
#define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
#define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
#define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
#define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
#define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
#define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
#define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
#define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
#define SQLITE_DELETE                9   /* Table Name      NULL            */
#define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
#define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
#define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
#define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
#define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
#define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
#define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
#define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
#define SQLITE_INSERT               18   /* Table Name      NULL            */
#define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
#define SQLITE_READ                 20   /* Table Name      Column Name     */
#define SQLITE_SELECT               21   /* NULL            NULL            */
#define SQLITE_TRANSACTION          22   /* Operation       NULL            */
#define SQLITE_UPDATE               23   /* Table Name      Column Name     */
#define SQLITE_ATTACH               24   /* Filename        NULL            */
#define SQLITE_DETACH               25   /* Database Name   NULL            */
#define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
#define SQLITE_REINDEX              27   /* Index Name      NULL            */
#define SQLITE_ANALYZE              28   /* Table Name      NULL            */
#define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
#define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
#define SQLITE_FUNCTION             31   /* NULL            Function Name   */
#define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
#define SQLITE_COPY                  0   /* No longer used */

/*
** CAPI3REF: Tracing And Profiling Functions
** EXPERIMENTAL
**
** These routines register callback functions that can be used for
** tracing and profiling the execution of SQL statements.
**
** ^The callback function registered by sqlite3_trace() is invoked at
** various times when an SQL statement is being run by [sqlite3_step()].
** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
** SQL statement text as the statement first begins executing.
** ^(Additional sqlite3_trace() callbacks might occur
** as each triggered subprogram is entered.  The callbacks for triggers
** contain a UTF-8 SQL comment that identifies the trigger.)^
**
** ^The callback function registered by sqlite3_profile() is invoked
** as each SQL statement finishes.  ^The profile callback contains
** the original statement text and an estimate of wall-clock time
** of how long that statement took to run.
*/
SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
   void(*xProfile)(void*,const char*,sqlite3_uint64), void*);

/*
** CAPI3REF: Query Progress Callbacks
**
** ^This routine configures a callback function - the
** progress callback - that is invoked periodically during long
** running calls to [sqlite3_exec()], [sqlite3_step()] and
** [sqlite3_get_table()].  An example use for this
** interface is to keep a GUI updated during a large query.
**
** ^If the progress callback returns non-zero, the operation is
** interrupted.  This feature can be used to implement a
** "Cancel" button on a GUI progress dialog box.
**
** The progress handler must not do anything that will modify
** the database connection that invoked the progress handler.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
*/
SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);

/*
** CAPI3REF: Opening A New Database Connection
**
** ^These routines open an SQLite database file whose name is given by the
** filename argument. ^The filename argument is interpreted as UTF-8 for
** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
** order for sqlite3_open16(). ^(A [database connection] handle is usually
** returned in *ppDb, even if an error occurs.  The only exception is that
** if SQLite is unable to allocate memory to hold the [sqlite3] object,
** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
** object.)^ ^(If the database is opened (and/or created) successfully, then
** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
** an English language description of the error following a failure of any
** of the sqlite3_open() routines.
**
** ^The default encoding for the database will be UTF-8 if
** sqlite3_open() or sqlite3_open_v2() is called and
** UTF-16 in the native byte order if sqlite3_open16() is used.
**
** Whether or not an error occurs when it is opened, resources
** associated with the [database connection] handle should be released by
** passing it to [sqlite3_close()] when it is no longer required.
**
** The sqlite3_open_v2() interface works like sqlite3_open()
** except that it accepts two additional parameters for additional control
** over the new database connection.  ^(The flags parameter to
** sqlite3_open_v2() can take one of
** the following three values, optionally combined with the
** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
** and/or [SQLITE_OPEN_PRIVATECACHE] flags:)^
**
** <dl>
** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
** <dd>The database is opened in read-only mode.  If the database does not
** already exist, an error is returned.</dd>)^
**
** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
** <dd>The database is opened for reading and writing if possible, or reading
** only if the file is write protected by the operating system.  In either
** case the database must already exist, otherwise an error is returned.</dd>)^
**
** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
** <dd>The database is opened for reading and writing, and is creates it if
** it does not already exist. This is the behavior that is always used for
** sqlite3_open() and sqlite3_open16().</dd>)^
** </dl>
**
** If the 3rd parameter to sqlite3_open_v2() is not one of the
** combinations shown above or one of the combinations shown above combined
** with the [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX],
** [SQLITE_OPEN_SHAREDCACHE] and/or [SQLITE_OPEN_SHAREDCACHE] flags,
** then the behavior is undefined.
**
** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
** opens in the multi-thread [threading mode] as long as the single-thread
** mode has not been set at compile-time or start-time.  ^If the
** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
** in the serialized [threading mode] unless single-thread was
** previously selected at compile-time or start-time.
** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
** eligible to use [shared cache mode], regardless of whether or not shared
** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
** participate in [shared cache mode] even if it is enabled.
**
** ^If the filename is ":memory:", then a private, temporary in-memory database
** is created for the connection.  ^This in-memory database will vanish when
** the database connection is closed.  Future versions of SQLite might
** make use of additional special filenames that begin with the ":" character.
** It is recommended that when a database filename actually does begin with
** a ":" character you should prefix the filename with a pathname such as
** "./" to avoid ambiguity.
**
** ^If the filename is an empty string, then a private, temporary
** on-disk database will be created.  ^This private database will be
** automatically deleted as soon as the database connection is closed.
**
** ^The fourth parameter to sqlite3_open_v2() is the name of the
** [sqlite3_vfs] object that defines the operating system interface that
** the new database connection should use.  ^If the fourth parameter is
** a NULL pointer then the default [sqlite3_vfs] object is used.
**
** <b>Note to Windows users:</b>  The encoding used for the filename argument
** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
** codepage is currently defined.  Filenames containing international
** characters must be converted to UTF-8 prior to passing them into
** sqlite3_open() or sqlite3_open_v2().
*/
SQLITE_API int sqlite3_open(
  const char *filename,   /* Database filename (UTF-8) */
  sqlite3 **ppDb          /* OUT: SQLite db handle */
);
SQLITE_API int sqlite3_open16(
  const void *filename,   /* Database filename (UTF-16) */
  sqlite3 **ppDb          /* OUT: SQLite db handle */
);
SQLITE_API int sqlite3_open_v2(
  const char *filename,   /* Database filename (UTF-8) */
  sqlite3 **ppDb,         /* OUT: SQLite db handle */
  int flags,              /* Flags */
  const char *zVfs        /* Name of VFS module to use */
);

/*
** CAPI3REF: Error Codes And Messages
**
** ^The sqlite3_errcode() interface returns the numeric [result code] or
** [extended result code] for the most recent failed sqlite3_* API call
** associated with a [database connection]. If a prior API call failed
** but the most recent API call succeeded, the return value from
** sqlite3_errcode() is undefined.  ^The sqlite3_extended_errcode()
** interface is the same except that it always returns the
** [extended result code] even when extended result codes are
** disabled.
**
** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
** text that describes the error, as either UTF-8 or UTF-16 respectively.
** ^(Memory to hold the error message string is managed internally.
** The application does not need to worry about freeing the result.
** However, the error string might be overwritten or deallocated by
** subsequent calls to other SQLite interface functions.)^
**
** When the serialized [threading mode] is in use, it might be the
** case that a second error occurs on a separate thread in between
** the time of the first error and the call to these interfaces.
** When that happens, the second error will be reported since these
** interfaces always report the most recent result.  To avoid
** this, each thread can obtain exclusive use of the [database connection] D
** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
** all calls to the interfaces listed here are completed.
**
** If an interface fails with SQLITE_MISUSE, that means the interface
** was invoked incorrectly by the application.  In that case, the
** error code and message may or may not be set.
*/
SQLITE_API int sqlite3_errcode(sqlite3 *db);
SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
SQLITE_API const char *sqlite3_errmsg(sqlite3*);
SQLITE_API const void *sqlite3_errmsg16(sqlite3*);

/*
** CAPI3REF: SQL Statement Object
** KEYWORDS: {prepared statement} {prepared statements}
**
** An instance of this object represents a single SQL statement.
** This object is variously known as a "prepared statement" or a
** "compiled SQL statement" or simply as a "statement".
**
** The life of a statement object goes something like this:
**
** <ol>
** <li> Create the object using [sqlite3_prepare_v2()] or a related
**      function.
** <li> Bind values to [host parameters] using the sqlite3_bind_*()
**      interfaces.
** <li> Run the SQL by calling [sqlite3_step()] one or more times.
** <li> Reset the statement using [sqlite3_reset()] then go back
**      to step 2.  Do this zero or more times.
** <li> Destroy the object using [sqlite3_finalize()].
** </ol>
**
** Refer to documentation on individual methods above for additional
** information.
*/
typedef struct sqlite3_stmt sqlite3_stmt;

/*
** CAPI3REF: Run-time Limits
**
** ^(This interface allows the size of various constructs to be limited
** on a connection by connection basis.  The first parameter is the
** [database connection] whose limit is to be set or queried.  The
** second parameter is one of the [limit categories] that define a
** class of constructs to be size limited.  The third parameter is the
** new limit for that construct.  The function returns the old limit.)^
**
** ^If the new limit is a negative number, the limit is unchanged.
** ^(For the limit category of SQLITE_LIMIT_XYZ there is a
** [limits | hard upper bound]
** set by a compile-time C preprocessor macro named
** [limits | SQLITE_MAX_XYZ].
** (The "_LIMIT_" in the name is changed to "_MAX_".))^
** ^Attempts to increase a limit above its hard upper bound are
** silently truncated to the hard upper bound.
**
** Run-time limits are intended for use in applications that manage
** both their own internal database and also databases that are controlled
** by untrusted external sources.  An example application might be a
** web browser that has its own databases for storing history and
** separate databases controlled by JavaScript applications downloaded
** off the Internet.  The internal databases can be given the
** large, default limits.  Databases managed by external sources can
** be given much smaller limits designed to prevent a denial of service
** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
** interface to further control untrusted SQL.  The size of the database
** created by an untrusted script can be contained using the
** [max_page_count] [PRAGMA].
**
** New run-time limit categories may be added in future releases.
*/
SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);

/*
** CAPI3REF: Run-Time Limit Categories
** KEYWORDS: {limit category} {*limit categories}
**
** These constants define various performance limits
** that can be lowered at run-time using [sqlite3_limit()].
** The synopsis of the meanings of the various limits is shown below.
** Additional information is available at [limits | Limits in SQLite].
**
** <dl>
** ^(<dt>SQLITE_LIMIT_LENGTH</dt>
** <dd>The maximum size of any string or BLOB or table row.<dd>)^
**
** ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
**
** ^(<dt>SQLITE_LIMIT_COLUMN</dt>
** <dd>The maximum number of columns in a table definition or in the
** result set of a [SELECT] or the maximum number of columns in an index
** or in an ORDER BY or GROUP BY clause.</dd>)^
**
** ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
** <dd>The maximum depth of the parse tree on any expression.</dd>)^
**
** ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
**
** ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
** <dd>The maximum number of instructions in a virtual machine program
** used to implement an SQL statement.</dd>)^
**
** ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
** <dd>The maximum number of arguments on a function.</dd>)^
**
** ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
**
** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
** <dd>The maximum length of the pattern argument to the [LIKE] or
** [GLOB] operators.</dd>)^
**
** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
** <dd>The maximum number of variables in an SQL statement that can
** be bound.</dd>)^
**
** ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
** <dd>The maximum depth of recursion for triggers.</dd>)^
** </dl>
*/
#define SQLITE_LIMIT_LENGTH                    0
#define SQLITE_LIMIT_SQL_LENGTH                1
#define SQLITE_LIMIT_COLUMN                    2
#define SQLITE_LIMIT_EXPR_DEPTH                3
#define SQLITE_LIMIT_COMPOUND_SELECT           4
#define SQLITE_LIMIT_VDBE_OP                   5
#define SQLITE_LIMIT_FUNCTION_ARG              6
#define SQLITE_LIMIT_ATTACHED                  7
#define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
#define SQLITE_LIMIT_VARIABLE_NUMBER           9
#define SQLITE_LIMIT_TRIGGER_DEPTH            10

/*
** CAPI3REF: Compiling An SQL Statement
** KEYWORDS: {SQL statement compiler}
**
** To execute an SQL query, it must first be compiled into a byte-code
** program using one of these routines.
**
** The first argument, "db", is a [database connection] obtained from a
** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
** [sqlite3_open16()].  The database connection must not have been closed.
**
** The second argument, "zSql", is the statement to be compiled, encoded
** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
** use UTF-16.
**
** ^If the nByte argument is less than zero, then zSql is read up to the
** first zero terminator. ^If nByte is non-negative, then it is the maximum
** number of  bytes read from zSql.  ^When nByte is non-negative, the
** zSql string ends at either the first '\000' or '\u0000' character or
** the nByte-th byte, whichever comes first. If the caller knows
** that the supplied string is nul-terminated, then there is a small
** performance advantage to be gained by passing an nByte parameter that
** is equal to the number of bytes in the input string <i>including</i>
** the nul-terminator bytes.
**
** ^If pzTail is not NULL then *pzTail is made to point to the first byte
** past the end of the first SQL statement in zSql.  These routines only
** compile the first statement in zSql, so *pzTail is left pointing to
** what remains uncompiled.
**
** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
** to NULL.  ^If the input text contains no SQL (if the input is an empty
** string or a comment) then *ppStmt is set to NULL.
** The calling procedure is responsible for deleting the compiled
** SQL statement using [sqlite3_finalize()] after it has finished with it.
** ppStmt may not be NULL.
**
** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
** otherwise an [error code] is returned.
**
** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
** recommended for all new programs. The two older interfaces are retained
** for backwards compatibility, but their use is discouraged.
** ^In the "v2" interfaces, the prepared statement
** that is returned (the [sqlite3_stmt] object) contains a copy of the
** original SQL text. This causes the [sqlite3_step()] interface to
** behave differently in three ways:
**
** <ol>
** <li>
** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
** always used to do, [sqlite3_step()] will automatically recompile the SQL
** statement and try to run it again.  ^If the schema has changed in
** a way that makes the statement no longer valid, [sqlite3_step()] will still
** return [SQLITE_SCHEMA].  But unlike the legacy behavior, [SQLITE_SCHEMA] is
** now a fatal error.  Calling [sqlite3_prepare_v2()] again will not make the
** error go away.  Note: use [sqlite3_errmsg()] to find the text
** of the parsing error that results in an [SQLITE_SCHEMA] return.
** </li>
**
** <li>
** ^When an error occurs, [sqlite3_step()] will return one of the detailed
** [error codes] or [extended error codes].  ^The legacy behavior was that
** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
** and the application would have to make a second call to [sqlite3_reset()]
** in order to find the underlying cause of the problem. With the "v2" prepare
** interfaces, the underlying reason for the error is returned immediately.
** </li>
**
** <li>
** ^If the value of a [parameter | host parameter] in the WHERE clause might
** change the query plan for a statement, then the statement may be
** automatically recompiled (as if there had been a schema change) on the first
** [sqlite3_step()] call following any change to the
** [sqlite3_bind_text | bindings] of the [parameter].
** </li>
** </ol>
*/
SQLITE_API int sqlite3_prepare(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
  int nByte,              /* Maximum length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
);
SQLITE_API int sqlite3_prepare_v2(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
  int nByte,              /* Maximum length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
);
SQLITE_API int sqlite3_prepare16(
  sqlite3 *db,            /* Database handle */
  const void *zSql,       /* SQL statement, UTF-16 encoded */
  int nByte,              /* Maximum length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
);
SQLITE_API int sqlite3_prepare16_v2(
  sqlite3 *db,            /* Database handle */
  const void *zSql,       /* SQL statement, UTF-16 encoded */
  int nByte,              /* Maximum length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
);

/*
** CAPI3REF: Retrieving Statement SQL
**
** ^This interface can be used to retrieve a saved copy of the original
** SQL text used to create a [prepared statement] if that statement was
** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
*/
SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Dynamically Typed Value Object
** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
**
** SQLite uses the sqlite3_value object to represent all values
** that can be stored in a database table. SQLite uses dynamic typing
** for the values it stores.  ^Values stored in sqlite3_value objects
** can be integers, floating point values, strings, BLOBs, or NULL.
**
** An sqlite3_value object may be either "protected" or "unprotected".
** Some interfaces require a protected sqlite3_value.  Other interfaces
** will accept either a protected or an unprotected sqlite3_value.
** Every interface that accepts sqlite3_value arguments specifies
** whether or not it requires a protected sqlite3_value.
**
** The terms "protected" and "unprotected" refer to whether or not
** a mutex is held.  A internal mutex is held for a protected
** sqlite3_value object but no mutex is held for an unprotected
** sqlite3_value object.  If SQLite is compiled to be single-threaded
** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
** or if SQLite is run in one of reduced mutex modes
** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
** then there is no distinction between protected and unprotected
** sqlite3_value objects and they can be used interchangeably.  However,
** for maximum code portability it is recommended that applications
** still make the distinction between between protected and unprotected
** sqlite3_value objects even when not strictly required.
**
** ^The sqlite3_value objects that are passed as parameters into the
** implementation of [application-defined SQL functions] are protected.
** ^The sqlite3_value object returned by
** [sqlite3_column_value()] is unprotected.
** Unprotected sqlite3_value objects may only be used with
** [sqlite3_result_value()] and [sqlite3_bind_value()].
** The [sqlite3_value_blob | sqlite3_value_type()] family of
** interfaces require protected sqlite3_value objects.
*/
typedef struct Mem sqlite3_value;

/*
** CAPI3REF: SQL Function Context Object
**
** The context in which an SQL function executes is stored in an
** sqlite3_context object.  ^A pointer to an sqlite3_context object
** is always first parameter to [application-defined SQL functions].
** The application-defined SQL function implementation will pass this
** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
** [sqlite3_aggregate_context()], [sqlite3_user_data()],
** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
** and/or [sqlite3_set_auxdata()].
*/
typedef struct sqlite3_context sqlite3_context;

/*
** CAPI3REF: Binding Values To Prepared Statements
** KEYWORDS: {host parameter} {host parameters} {host parameter name}
** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
**
** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
** literals may be replaced by a [parameter] that matches one of following
** templates:
**
** <ul>
** <li>  ?
** <li>  ?NNN
** <li>  :VVV
** <li>  @VVV
** <li>  $VVV
** </ul>
**
** In the templates above, NNN represents an integer literal,
** and VVV represents an alphanumeric identifer.)^  ^The values of these
** parameters (also called "host parameter names" or "SQL parameters")
** can be set using the sqlite3_bind_*() routines defined here.
**
** ^The first argument to the sqlite3_bind_*() routines is always
** a pointer to the [sqlite3_stmt] object returned from
** [sqlite3_prepare_v2()] or its variants.
**
** ^The second argument is the index of the SQL parameter to be set.
** ^The leftmost SQL parameter has an index of 1.  ^When the same named
** SQL parameter is used more than once, second and subsequent
** occurrences have the same index as the first occurrence.
** ^The index for named parameters can be looked up using the
** [sqlite3_bind_parameter_index()] API if desired.  ^The index
** for "?NNN" parameters is the value of NNN.
** ^The NNN value must be between 1 and the [sqlite3_limit()]
** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
**
** ^The third argument is the value to bind to the parameter.
**
** ^(In those routines that have a fourth argument, its value is the
** number of bytes in the parameter.  To be clear: the value is the
** number of <u>bytes</u> in the value, not the number of characters.)^
** ^If the fourth parameter is negative, the length of the string is
** the number of bytes up to the first zero terminator.
**
** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
** string after SQLite has finished with it. ^If the fifth argument is
** the special value [SQLITE_STATIC], then SQLite assumes that the
** information is in static, unmanaged space and does not need to be freed.
** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
** SQLite makes its own private copy of the data immediately, before
** the sqlite3_bind_*() routine returns.
**
** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
** (just an integer to hold its size) while it is being processed.
** Zeroblobs are intended to serve as placeholders for BLOBs whose
** content is later written using
** [sqlite3_blob_open | incremental BLOB I/O] routines.
** ^A negative value for the zeroblob results in a zero-length BLOB.
**
** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
** for the [prepared statement] or with a prepared statement for which
** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
** routine is passed a [prepared statement] that has been finalized, the
** result is undefined and probably harmful.
**
** ^Bindings are not cleared by the [sqlite3_reset()] routine.
** ^Unbound parameters are interpreted as NULL.
**
** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
** [error code] if anything goes wrong.
** ^[SQLITE_RANGE] is returned if the parameter
** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
**
** See also: [sqlite3_bind_parameter_count()],
** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
*/
SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
SQLITE_API int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*));
SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);

/*
** CAPI3REF: Number Of SQL Parameters
**
** ^This routine can be used to find the number of [SQL parameters]
** in a [prepared statement].  SQL parameters are tokens of the
** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
** placeholders for values that are [sqlite3_bind_blob | bound]
** to the parameters at a later time.
**
** ^(This routine actually returns the index of the largest (rightmost)
** parameter. For all forms except ?NNN, this will correspond to the
** number of unique parameters.  If parameters of the ?NNN form are used,
** there may be gaps in the list.)^
**
** See also: [sqlite3_bind_blob|sqlite3_bind()],
** [sqlite3_bind_parameter_name()], and
** [sqlite3_bind_parameter_index()].
*/
SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);

/*
** CAPI3REF: Name Of A Host Parameter
**
** ^The sqlite3_bind_parameter_name(P,N) interface returns
** the name of the N-th [SQL parameter] in the [prepared statement] P.
** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
** respectively.
** In other words, the initial ":" or "$" or "@" or "?"
** is included as part of the name.)^
** ^Parameters of the form "?" without a following integer have no name
** and are referred to as "nameless" or "anonymous parameters".
**
** ^The first host parameter has an index of 1, not 0.
**
** ^If the value N is out of range or if the N-th parameter is
** nameless, then NULL is returned.  ^The returned string is
** always in UTF-8 encoding even if the named parameter was
** originally specified as UTF-16 in [sqlite3_prepare16()] or
** [sqlite3_prepare16_v2()].
**
** See also: [sqlite3_bind_blob|sqlite3_bind()],
** [sqlite3_bind_parameter_count()], and
** [sqlite3_bind_parameter_index()].
*/
SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);

/*
** CAPI3REF: Index Of A Parameter With A Given Name
**
** ^Return the index of an SQL parameter given its name.  ^The
** index value returned is suitable for use as the second
** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
** is returned if no matching parameter is found.  ^The parameter
** name must be given in UTF-8 even if the original statement
** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
**
** See also: [sqlite3_bind_blob|sqlite3_bind()],
** [sqlite3_bind_parameter_count()], and
** [sqlite3_bind_parameter_index()].
*/
SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);

/*
** CAPI3REF: Reset All Bindings On A Prepared Statement
**
** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
** the [sqlite3_bind_blob | bindings] on a [prepared statement].
** ^Use this routine to reset all host parameters to NULL.
*/
SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);

/*
** CAPI3REF: Number Of Columns In A Result Set
**
** ^Return the number of columns in the result set returned by the
** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
** statement that does not return data (for example an [UPDATE]).
*/
SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Column Names In A Result Set
**
** ^These routines return the name assigned to a particular column
** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
** interface returns a pointer to a zero-terminated UTF-8 string
** and sqlite3_column_name16() returns a pointer to a zero-terminated
** UTF-16 string.  ^The first parameter is the [prepared statement]
** that implements the [SELECT] statement. ^The second parameter is the
** column number.  ^The leftmost column is number 0.
**
** ^The returned string pointer is valid until either the [prepared statement]
** is destroyed by [sqlite3_finalize()] or until the next call to
** sqlite3_column_name() or sqlite3_column_name16() on the same column.
**
** ^If sqlite3_malloc() fails during the processing of either routine
** (for example during a conversion from UTF-8 to UTF-16) then a
** NULL pointer is returned.
**
** ^The name of a result column is the value of the "AS" clause for
** that column, if there is an AS clause.  If there is no AS clause
** then the name of the column is unspecified and may change from
** one release of SQLite to the next.
*/
SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);

/*
** CAPI3REF: Source Of Data In A Query Result
**
** ^These routines provide a means to determine the database, table, and
** table column that is the origin of a particular result column in
** [SELECT] statement.
** ^The name of the database or table or column can be returned as
** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
** the database name, the _table_ routines return the table name, and
** the origin_ routines return the column name.
** ^The returned string is valid until the [prepared statement] is destroyed
** using [sqlite3_finalize()] or until the same information is requested
** again in a different encoding.
**
** ^The names returned are the original un-aliased names of the
** database, table, and column.
**
** ^The first argument to these interfaces is a [prepared statement].
** ^These functions return information about the Nth result column returned by
** the statement, where N is the second function argument.
** ^The left-most column is column 0 for these routines.
**
** ^If the Nth column returned by the statement is an expression or
** subquery and is not a column value, then all of these functions return
** NULL.  ^These routine might also return NULL if a memory allocation error
** occurs.  ^Otherwise, they return the name of the attached database, table,
** or column that query result column was extracted from.
**
** ^As with all other SQLite APIs, those whose names end with "16" return
** UTF-16 encoded strings and the other functions return UTF-8.
**
** ^These APIs are only available if the library was compiled with the
** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
**
** If two or more threads call one or more of these routines against the same
** prepared statement and column at the same time then the results are
** undefined.
**
** If two or more threads call one or more
** [sqlite3_column_database_name | column metadata interfaces]
** for the same [prepared statement] and result column
** at the same time then the results are undefined.
*/
SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);

/*
** CAPI3REF: Declared Datatype Of A Query Result
**
** ^(The first parameter is a [prepared statement].
** If this statement is a [SELECT] statement and the Nth column of the
** returned result set of that [SELECT] is a table column (not an
** expression or subquery) then the declared type of the table
** column is returned.)^  ^If the Nth column of the result set is an
** expression or subquery, then a NULL pointer is returned.
** ^The returned string is always UTF-8 encoded.
**
** ^(For example, given the database schema:
**
** CREATE TABLE t1(c1 VARIANT);
**
** and the following statement to be compiled:
**
** SELECT c1 + 1, c1 FROM t1;
**
** this routine would return the string "VARIANT" for the second result
** column (i==1), and a NULL pointer for the first result column (i==0).)^
**
** ^SQLite uses dynamic run-time typing.  ^So just because a column
** is declared to contain a particular type does not mean that the
** data stored in that column is of the declared type.  SQLite is
** strongly typed, but the typing is dynamic not static.  ^Type
** is associated with individual values, not with the containers
** used to hold those values.
*/
SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);

/*
** CAPI3REF: Evaluate An SQL Statement
**
** After a [prepared statement] has been prepared using either
** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
** must be called one or more times to evaluate the statement.
**
** The details of the behavior of the sqlite3_step() interface depend
** on whether the statement was prepared using the newer "v2" interface
** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
** new "v2" interface is recommended for new applications but the legacy
** interface will continue to be supported.
**
** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
** ^With the "v2" interface, any of the other [result codes] or
** [extended result codes] might be returned as well.
**
** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
** database locks it needs to do its job.  ^If the statement is a [COMMIT]
** or occurs outside of an explicit transaction, then you can retry the
** statement.  If the statement is not a [COMMIT] and occurs within a
** explicit transaction then you should rollback the transaction before
** continuing.
**
** ^[SQLITE_DONE] means that the statement has finished executing
** successfully.  sqlite3_step() should not be called again on this virtual
** machine without first calling [sqlite3_reset()] to reset the virtual
** machine back to its initial state.
**
** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
** is returned each time a new row of data is ready for processing by the
** caller. The values may be accessed using the [column access functions].
** sqlite3_step() is called again to retrieve the next row of data.
**
** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
** violation) has occurred.  sqlite3_step() should not be called again on
** the VM. More information may be found by calling [sqlite3_errmsg()].
** ^With the legacy interface, a more specific error code (for example,
** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
** can be obtained by calling [sqlite3_reset()] on the
** [prepared statement].  ^In the "v2" interface,
** the more specific error code is returned directly by sqlite3_step().
**
** [SQLITE_MISUSE] means that the this routine was called inappropriately.
** Perhaps it was called on a [prepared statement] that has
** already been [sqlite3_finalize | finalized] or on one that had
** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
** be the case that the same database connection is being used by two or
** more threads at the same moment in time.
**
** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
** API always returns a generic error code, [SQLITE_ERROR], following any
** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
** specific [error codes] that better describes the error.
** We admit that this is a goofy design.  The problem has been fixed
** with the "v2" interface.  If you prepare all of your SQL statements
** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
** then the more specific [error codes] are returned directly
** by sqlite3_step().  The use of the "v2" interface is recommended.
*/
SQLITE_API int sqlite3_step(sqlite3_stmt*);

/*
** CAPI3REF: Number of columns in a result set
**
** ^The sqlite3_data_count(P) the number of columns in the
** of the result set of [prepared statement] P.
*/
SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Fundamental Datatypes
** KEYWORDS: SQLITE_TEXT
**
** ^(Every value in SQLite has one of five fundamental datatypes:
**
** <ul>
** <li> 64-bit signed integer
** <li> 64-bit IEEE floating point number
** <li> string
** <li> BLOB
** <li> NULL
** </ul>)^
**
** These constants are codes for each of those types.
**
** Note that the SQLITE_TEXT constant was also used in SQLite version 2
** for a completely different meaning.  Software that links against both
** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
** SQLITE_TEXT.
*/
#define SQLITE_INTEGER  1
#define SQLITE_FLOAT    2
#define SQLITE_BLOB     4
#define SQLITE_NULL     5
#ifdef SQLITE_TEXT
# undef SQLITE_TEXT
#else
# define SQLITE_TEXT     3
#endif
#define SQLITE3_TEXT     3

/*
** CAPI3REF: Result Values From A Query
** KEYWORDS: {column access functions}
**
** These routines form the "result set" interface.
**
** ^These routines return information about a single column of the current
** result row of a query.  ^In every case the first argument is a pointer
** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
** that was returned from [sqlite3_prepare_v2()] or one of its variants)
** and the second argument is the index of the column for which information
** should be returned. ^The leftmost column of the result set has the index 0.
** ^The number of columns in the result can be determined using
** [sqlite3_column_count()].
**
** If the SQL statement does not currently point to a valid row, or if the
** column index is out of range, the result is undefined.
** These routines may only be called when the most recent call to
** [sqlite3_step()] has returned [SQLITE_ROW] and neither
** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
** If any of these routines are called after [sqlite3_reset()] or
** [sqlite3_finalize()] or after [sqlite3_step()] has returned
** something other than [SQLITE_ROW], the results are undefined.
** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
** are called from a different thread while any of these routines
** are pending, then the results are undefined.
**
** ^The sqlite3_column_type() routine returns the
** [SQLITE_INTEGER | datatype code] for the initial data type
** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
** returned by sqlite3_column_type() is only meaningful if no type
** conversions have occurred as described below.  After a type conversion,
** the value returned by sqlite3_column_type() is undefined.  Future
** versions of SQLite may change the behavior of sqlite3_column_type()
** following a type conversion.
**
** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
** routine returns the number of bytes in that BLOB or string.
** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
** the string to UTF-8 and then returns the number of bytes.
** ^If the result is a numeric value then sqlite3_column_bytes() uses
** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
** the number of bytes in that string.
** ^The value returned does not include the zero terminator at the end
** of the string.  ^For clarity: the value returned is the number of
** bytes in the string, not the number of characters.
**
** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
** even empty strings, are always zero terminated.  ^The return
** value from sqlite3_column_blob() for a zero-length BLOB is an arbitrary
** pointer, possibly even a NULL pointer.
**
** ^The sqlite3_column_bytes16() routine is similar to sqlite3_column_bytes()
** but leaves the result in UTF-16 in native byte order instead of UTF-8.
** ^The zero terminator is not included in this count.
**
** ^The object returned by [sqlite3_column_value()] is an
** [unprotected sqlite3_value] object.  An unprotected sqlite3_value object
** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()].
** If the [unprotected sqlite3_value] object returned by
** [sqlite3_column_value()] is used in any other way, including calls
** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
** or [sqlite3_value_bytes()], then the behavior is undefined.
**
** These routines attempt to convert the value where appropriate.  ^For
** example, if the internal representation is FLOAT and a text result
** is requested, [sqlite3_snprintf()] is used internally to perform the
** conversion automatically.  ^(The following table details the conversions
** that are applied:
**
** <blockquote>
** <table border="1">
** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
**
** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
** <tr><td>  NULL    <td>   TEXT    <td> Result is NULL pointer
** <tr><td>  NULL    <td>   BLOB    <td> Result is NULL pointer
** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
** <tr><td>  FLOAT   <td> INTEGER   <td> Convert from float to integer
** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
** <tr><td>  FLOAT   <td>   BLOB    <td> Same as FLOAT->TEXT
** <tr><td>  TEXT    <td> INTEGER   <td> Use atoi()
** <tr><td>  TEXT    <td>  FLOAT    <td> Use atof()
** <tr><td>  TEXT    <td>   BLOB    <td> No change
** <tr><td>  BLOB    <td> INTEGER   <td> Convert to TEXT then use atoi()
** <tr><td>  BLOB    <td>  FLOAT    <td> Convert to TEXT then use atof()
** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
** </table>
** </blockquote>)^
**
** The table above makes reference to standard C library functions atoi()
** and atof().  SQLite does not really use these functions.  It has its
** own equivalent internal routines.  The atoi() and atof() names are
** used in the table for brevity and because they are familiar to most
** C programmers.
**
** ^Note that when type conversions occur, pointers returned by prior
** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
** sqlite3_column_text16() may be invalidated.
** ^(Type conversions and pointer invalidations might occur
** in the following cases:
**
** <ul>
** <li> The initial content is a BLOB and sqlite3_column_text() or
**      sqlite3_column_text16() is called.  A zero-terminator might
**      need to be added to the string.</li>
** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
**      sqlite3_column_text16() is called.  The content must be converted
**      to UTF-16.</li>
** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
**      sqlite3_column_text() is called.  The content must be converted
**      to UTF-8.</li>
** </ul>)^
**
** ^Conversions between UTF-16be and UTF-16le are always done in place and do
** not invalidate a prior pointer, though of course the content of the buffer
** that the prior pointer points to will have been modified.  Other kinds
** of conversion are done in place when it is possible, but sometimes they
** are not possible and in those cases prior pointers are invalidated.
**
** ^(The safest and easiest to remember policy is to invoke these routines
** in one of the following ways:
**
** <ul>
**  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
**  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
**  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
** </ul>)^
**
** In other words, you should call sqlite3_column_text(),
** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
** into the desired format, then invoke sqlite3_column_bytes() or
** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
** to sqlite3_column_text() or sqlite3_column_blob() with calls to
** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
** with calls to sqlite3_column_bytes().
**
** ^The pointers returned are valid until a type conversion occurs as
** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
** and BLOBs is freed automatically.  Do <b>not</b> pass the pointers returned
** [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
** [sqlite3_free()].
**
** ^(If a memory allocation error occurs during the evaluation of any
** of these routines, a default value is returned.  The default value
** is either the integer 0, the floating point number 0.0, or a NULL
** pointer.  Subsequent calls to [sqlite3_errcode()] will return
** [SQLITE_NOMEM].)^
*/
SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);

/*
** CAPI3REF: Destroy A Prepared Statement Object
**
** ^The sqlite3_finalize() function is called to delete a [prepared statement].
** ^If the statement was executed successfully or not executed at all, then
** SQLITE_OK is returned. ^If execution of the statement failed then an
** [error code] or [extended error code] is returned.
**
** ^This routine can be called at any point during the execution of the
** [prepared statement].  ^If the virtual machine has not
** completed execution when this routine is called, that is like
** encountering an error or an [sqlite3_interrupt | interrupt].
** ^Incomplete updates may be rolled back and transactions canceled,
** depending on the circumstances, and the
** [error code] returned will be [SQLITE_ABORT].
*/
SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Reset A Prepared Statement Object
**
** The sqlite3_reset() function is called to reset a [prepared statement]
** object back to its initial state, ready to be re-executed.
** ^Any SQL statement variables that had values bound to them using
** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
** Use [sqlite3_clear_bindings()] to reset the bindings.
**
** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
** back to the beginning of its program.
**
** ^If the most recent call to [sqlite3_step(S)] for the
** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
** or if [sqlite3_step(S)] has never before been called on S,
** then [sqlite3_reset(S)] returns [SQLITE_OK].
**
** ^If the most recent call to [sqlite3_step(S)] for the
** [prepared statement] S indicated an error, then
** [sqlite3_reset(S)] returns an appropriate [error code].
**
** ^The [sqlite3_reset(S)] interface does not change the values
** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
*/
SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Create Or Redefine SQL Functions
** KEYWORDS: {function creation routines}
** KEYWORDS: {application-defined SQL function}
** KEYWORDS: {application-defined SQL functions}
**
** ^These two functions (collectively known as "function creation routines")
** are used to add SQL functions or aggregates or to redefine the behavior
** of existing SQL functions or aggregates.  The only difference between the
** two is that the second parameter, the name of the (scalar) function or
** aggregate, is encoded in UTF-8 for sqlite3_create_function() and UTF-16
** for sqlite3_create_function16().
**
** ^The first parameter is the [database connection] to which the SQL
** function is to be added.  ^If an application uses more than one database
** connection then application-defined SQL functions must be added
** to each database connection separately.
**
** The second parameter is the name of the SQL function to be created or
** redefined.  ^The length of the name is limited to 255 bytes, exclusive of
** the zero-terminator.  Note that the name length limit is in bytes, not
** characters.  ^Any attempt to create a function with a longer name
** will result in [SQLITE_ERROR] being returned.
**
** ^The third parameter (nArg)
** is the number of arguments that the SQL function or
** aggregate takes. ^If this parameter is -1, then the SQL function or
** aggregate may take any number of arguments between 0 and the limit
** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
** parameter is less than -1 or greater than 127 then the behavior is
** undefined.
**
** The fourth parameter, eTextRep, specifies what
** [SQLITE_UTF8 | text encoding] this SQL function prefers for
** its parameters.  Any SQL function implementation should be able to work
** work with UTF-8, UTF-16le, or UTF-16be.  But some implementations may be
** more efficient with one encoding than another.  ^An application may
** invoke sqlite3_create_function() or sqlite3_create_function16() multiple
** times with the same function but with different values of eTextRep.
** ^When multiple implementations of the same function are available, SQLite
** will pick the one that involves the least amount of data conversion.
** If there is only a single implementation which does not care what text
** encoding is used, then the fourth argument should be [SQLITE_ANY].
**
** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
** function can gain access to this pointer using [sqlite3_user_data()].)^
**
** The seventh, eighth and ninth parameters, xFunc, xStep and xFinal, are
** pointers to C-language functions that implement the SQL function or
** aggregate. ^A scalar SQL function requires an implementation of the xFunc
** callback only; NULL pointers should be passed as the xStep and xFinal
** parameters. ^An aggregate SQL function requires an implementation of xStep
** and xFinal and NULL should be passed for xFunc. ^To delete an existing
** SQL function or aggregate, pass NULL for all three function callbacks.
**
** ^It is permitted to register multiple implementations of the same
** functions with the same name but with either differing numbers of
** arguments or differing preferred text encodings.  ^SQLite will use
** the implementation that most closely matches the way in which the
** SQL function is used.  ^A function implementation with a non-negative
** nArg parameter is a better match than a function implementation with
** a negative nArg.  ^A function where the preferred text encoding
** matches the database encoding is a better
** match than a function where the encoding is different.
** ^A function where the encoding difference is between UTF16le and UTF16be
** is a closer match than a function where the encoding difference is
** between UTF8 and UTF16.
**
** ^Built-in functions may be overloaded by new application-defined functions.
** ^The first application-defined function with a given name overrides all
** built-in functions in the same [database connection] with the same name.
** ^Subsequent application-defined functions of the same name only override
** prior application-defined functions that are an exact match for the
** number of parameters and preferred encoding.
**
** ^An application-defined function is permitted to call other
** SQLite interfaces.  However, such calls must not
** close the database connection nor finalize or reset the prepared
** statement in which the function is running.
*/
SQLITE_API int sqlite3_create_function(
  sqlite3 *db,
  const char *zFunctionName,
  int nArg,
  int eTextRep,
  void *pApp,
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  void (*xFinal)(sqlite3_context*)
);
SQLITE_API int sqlite3_create_function16(
  sqlite3 *db,
  const void *zFunctionName,
  int nArg,
  int eTextRep,
  void *pApp,
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  void (*xFinal)(sqlite3_context*)
);

/*
** CAPI3REF: Text Encodings
**
** These constant define integer codes that represent the various
** text encodings supported by SQLite.
*/
#define SQLITE_UTF8           1
#define SQLITE_UTF16LE        2
#define SQLITE_UTF16BE        3
#define SQLITE_UTF16          4    /* Use native byte order */
#define SQLITE_ANY            5    /* sqlite3_create_function only */
#define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */

/*
** CAPI3REF: Deprecated Functions
** DEPRECATED
**
** These functions are [deprecated].  In order to maintain
** backwards compatibility with older code, these functions continue
** to be supported.  However, new applications should avoid
** the use of these functions.  To help encourage people to avoid
** using these functions, we are not going to tell you what they do.
*/
#ifndef SQLITE_OMIT_DEPRECATED
SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),void*,sqlite3_int64);
#endif

/*
** CAPI3REF: Obtaining SQL Function Parameter Values
**
** The C-language implementation of SQL functions and aggregates uses
** this set of interface routines to access the parameter values on
** the function or aggregate.
**
** The xFunc (for scalar functions) or xStep (for aggregates) parameters
** to [sqlite3_create_function()] and [sqlite3_create_function16()]
** define callbacks that implement the SQL functions and aggregates.
** The 4th parameter to these callbacks is an array of pointers to
** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
** each parameter to the SQL function.  These routines are used to
** extract values from the [sqlite3_value] objects.
**
** These routines work only with [protected sqlite3_value] objects.
** Any attempt to use these routines on an [unprotected sqlite3_value]
** object results in undefined behavior.
**
** ^These routines work just like the corresponding [column access functions]
** except that  these routines take a single [protected sqlite3_value] object
** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
**
** ^The sqlite3_value_text16() interface extracts a UTF-16 string
** in the native byte-order of the host machine.  ^The
** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
** extract UTF-16 strings as big-endian and little-endian respectively.
**
** ^(The sqlite3_value_numeric_type() interface attempts to apply
** numeric affinity to the value.  This means that an attempt is
** made to convert the value to an integer or floating point.  If
** such a conversion is possible without loss of information (in other
** words, if the value is a string that looks like a number)
** then the conversion is performed.  Otherwise no conversion occurs.
** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
**
** Please pay particular attention to the fact that the pointer returned
** from [sqlite3_value_blob()], [sqlite3_value_text()], or
** [sqlite3_value_text16()] can be invalidated by a subsequent call to
** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
** or [sqlite3_value_text16()].
**
** These routines must be called from the same thread as
** the SQL function that supplied the [sqlite3_value*] parameters.
*/
SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
SQLITE_API double sqlite3_value_double(sqlite3_value*);
SQLITE_API int sqlite3_value_int(sqlite3_value*);
SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
SQLITE_API int sqlite3_value_type(sqlite3_value*);
SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);

/*
** CAPI3REF: Obtain Aggregate Function Context
**
** Implementions of aggregate SQL functions use this
** routine to allocate memory for storing their state.
**
** ^The first time the sqlite3_aggregate_context(C,N) routine is called
** for a particular aggregate function, SQLite
** allocates N of memory, zeroes out that memory, and returns a pointer
** to the new memory. ^On second and subsequent calls to
** sqlite3_aggregate_context() for the same aggregate function instance,
** the same buffer is returned.  Sqlite3_aggregate_context() is normally
** called once for each invocation of the xStep callback and then one
** last time when the xFinal callback is invoked.  ^(When no rows match
** an aggregate query, the xStep() callback of the aggregate function
** implementation is never called and xFinal() is called exactly once.
** In those cases, sqlite3_aggregate_context() might be called for the
** first time from within xFinal().)^
**
** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer if N is
** less than or equal to zero or if a memory allocate error occurs.
**
** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
** determined by the N parameter on first successful call.  Changing the
** value of N in subsequent call to sqlite3_aggregate_context() within
** the same aggregate function instance will not resize the memory
** allocation.)^
**
** ^SQLite automatically frees the memory allocated by
** sqlite3_aggregate_context() when the aggregate query concludes.
**
** The first parameter must be a copy of the
** [sqlite3_context | SQL function context] that is the first parameter
** to the xStep or xFinal callback routine that implements the aggregate
** function.
**
** This routine must be called from the same thread in which
** the aggregate SQL function is running.
*/
SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);

/*
** CAPI3REF: User Data For Functions
**
** ^The sqlite3_user_data() interface returns a copy of
** the pointer that was the pUserData parameter (the 5th parameter)
** of the [sqlite3_create_function()]
** and [sqlite3_create_function16()] routines that originally
** registered the application defined function.
**
** This routine must be called from the same thread in which
** the application-defined function is running.
*/
SQLITE_API void *sqlite3_user_data(sqlite3_context*);

/*
** CAPI3REF: Database Connection For Functions
**
** ^The sqlite3_context_db_handle() interface returns a copy of
** the pointer to the [database connection] (the 1st parameter)
** of the [sqlite3_create_function()]
** and [sqlite3_create_function16()] routines that originally
** registered the application defined function.
*/
SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);

/*
** CAPI3REF: Function Auxiliary Data
**
** The following two functions may be used by scalar SQL functions to
** associate metadata with argument values. If the same value is passed to
** multiple invocations of the same SQL function during query execution, under
** some circumstances the associated metadata may be preserved. This may
** be used, for example, to add a regular-expression matching scalar
** function. The compiled version of the regular expression is stored as
** metadata associated with the SQL value passed as the regular expression
** pattern.  The compiled regular expression can be reused on multiple
** invocations of the same function so that the original pattern string
** does not need to be recompiled on each invocation.
**
** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
** associated by the sqlite3_set_auxdata() function with the Nth argument
** value to the application-defined function. ^If no metadata has been ever
** been set for the Nth argument of the function, or if the corresponding
** function parameter has changed since the meta-data was set,
** then sqlite3_get_auxdata() returns a NULL pointer.
**
** ^The sqlite3_set_auxdata() interface saves the metadata
** pointed to by its 3rd parameter as the metadata for the N-th
** argument of the application-defined function.  Subsequent
** calls to sqlite3_get_auxdata() might return this data, if it has
** not been destroyed.
** ^If it is not NULL, SQLite will invoke the destructor
** function given by the 4th parameter to sqlite3_set_auxdata() on
** the metadata when the corresponding function parameter changes
** or when the SQL statement completes, whichever comes first.
**
** SQLite is free to call the destructor and drop metadata on any
** parameter of any function at any time.  ^The only guarantee is that
** the destructor will be called before the metadata is dropped.
**
** ^(In practice, metadata is preserved between function calls for
** expressions that are constant at compile time. This includes literal
** values and [parameters].)^
**
** These routines must be called from the same thread in which
** the SQL function is running.
*/
SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));


/*
** CAPI3REF: Constants Defining Special Destructor Behavior
**
** These are special values for the destructor that is passed in as the
** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
** argument is SQLITE_STATIC, it means that the content pointer is constant
** and will never change.  It does not need to be destroyed.  ^The
** SQLITE_TRANSIENT value means that the content will likely change in
** the near future and that SQLite should make its own private copy of
** the content before returning.
**
** The typedef is necessary to work around problems in certain
** C++ compilers.  See ticket #2191.
*/
typedef void (*sqlite3_destructor_type)(void*);
#define SQLITE_STATIC      ((sqlite3_destructor_type)0)
#define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)

/*
** CAPI3REF: Setting The Result Of An SQL Function
**
** These routines are used by the xFunc or xFinal callbacks that
** implement SQL functions and aggregates.  See
** [sqlite3_create_function()] and [sqlite3_create_function16()]
** for additional information.
**
** These functions work very much like the [parameter binding] family of
** functions used to bind values to host parameters in prepared statements.
** Refer to the [SQL parameter] documentation for additional information.
**
** ^The sqlite3_result_blob() interface sets the result from
** an application-defined function to be the BLOB whose content is pointed
** to by the second parameter and which is N bytes long where N is the
** third parameter.
**
** ^The sqlite3_result_zeroblob() interfaces set the result of
** the application-defined function to be a BLOB containing all zero
** bytes and N bytes in size, where N is the value of the 2nd parameter.
**
** ^The sqlite3_result_double() interface sets the result from
** an application-defined function to be a floating point value specified
** by its 2nd argument.
**
** ^The sqlite3_result_error() and sqlite3_result_error16() functions
** cause the implemented SQL function to throw an exception.
** ^SQLite uses the string pointed to by the
** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
** as the text of an error message.  ^SQLite interprets the error
** message string from sqlite3_result_error() as UTF-8. ^SQLite
** interprets the string from sqlite3_result_error16() as UTF-16 in native
** byte order.  ^If the third parameter to sqlite3_result_error()
** or sqlite3_result_error16() is negative then SQLite takes as the error
** message all text up through the first zero character.
** ^If the third parameter to sqlite3_result_error() or
** sqlite3_result_error16() is non-negative then SQLite takes that many
** bytes (not characters) from the 2nd parameter as the error message.
** ^The sqlite3_result_error() and sqlite3_result_error16()
** routines make a private copy of the error message text before
** they return.  Hence, the calling function can deallocate or
** modify the text after they return without harm.
** ^The sqlite3_result_error_code() function changes the error code
** returned by SQLite as a result of an error in a function.  ^By default,
** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
**
** ^The sqlite3_result_toobig() interface causes SQLite to throw an error
** indicating that a string or BLOB is too long to represent.
**
** ^The sqlite3_result_nomem() interface causes SQLite to throw an error
** indicating that a memory allocation failed.
**
** ^The sqlite3_result_int() interface sets the return value
** of the application-defined function to be the 32-bit signed integer
** value given in the 2nd argument.
** ^The sqlite3_result_int64() interface sets the return value
** of the application-defined function to be the 64-bit signed integer
** value given in the 2nd argument.
**
** ^The sqlite3_result_null() interface sets the return value
** of the application-defined function to be NULL.
**
** ^The sqlite3_result_text(), sqlite3_result_text16(),
** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
** set the return value of the application-defined function to be
** a text string which is represented as UTF-8, UTF-16 native byte order,
** UTF-16 little endian, or UTF-16 big endian, respectively.
** ^SQLite takes the text result from the application from
** the 2nd parameter of the sqlite3_result_text* interfaces.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is negative, then SQLite takes result text from the 2nd parameter
** through the first zero character.
** ^If the 3rd parameter to the sqlite3_result_text* interfaces
** is non-negative, then as many bytes (not characters) of the text
** pointed to by the 2nd parameter are taken as the application-defined
** function result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
** function as the destructor on the text or BLOB result when it has
** finished using that result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
** assumes that the text or BLOB result is in constant space and does not
** copy the content of the parameter nor call a destructor on the content
** when it has finished using that result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
** then SQLite makes a copy of the result into space obtained from
** from [sqlite3_malloc()] before it returns.
**
** ^The sqlite3_result_value() interface sets the result of
** the application-defined function to be a copy the
** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
** so that the [sqlite3_value] specified in the parameter may change or
** be deallocated after sqlite3_result_value() returns without harm.
** ^A [protected sqlite3_value] object may always be used where an
** [unprotected sqlite3_value] object is required, so either
** kind of [sqlite3_value] object can be used with this interface.
**
** If these routines are called from within the different thread
** than the one containing the application-defined function that received
** the [sqlite3_context] pointer, the results are undefined.
*/
SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
SQLITE_API void sqlite3_result_null(sqlite3_context*);
SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);

/*
** CAPI3REF: Define New Collating Sequences
**
** These functions are used to add new collation sequences to the
** [database connection] specified as the first argument.
**
** ^The name of the new collation sequence is specified as a UTF-8 string
** for sqlite3_create_collation() and sqlite3_create_collation_v2()
** and a UTF-16 string for sqlite3_create_collation16(). ^In all cases
** the name is passed as the second function argument.
**
** ^The third argument may be one of the constants [SQLITE_UTF8],
** [SQLITE_UTF16LE], or [SQLITE_UTF16BE], indicating that the user-supplied
** routine expects to be passed pointers to strings encoded using UTF-8,
** UTF-16 little-endian, or UTF-16 big-endian, respectively. ^The
** third argument might also be [SQLITE_UTF16] to indicate that the routine
** expects pointers to be UTF-16 strings in the native byte order, or the
** argument can be [SQLITE_UTF16_ALIGNED] if the
** the routine expects pointers to 16-bit word aligned strings
** of UTF-16 in the native byte order.
**
** A pointer to the user supplied routine must be passed as the fifth
** argument.  ^If it is NULL, this is the same as deleting the collation
** sequence (so that SQLite cannot call it anymore).
** ^Each time the application supplied function is invoked, it is passed
** as its first parameter a copy of the void* passed as the fourth argument
** to sqlite3_create_collation() or sqlite3_create_collation16().
**
** ^The remaining arguments to the application-supplied routine are two strings,
** each represented by a (length, data) pair and encoded in the encoding
** that was passed as the third argument when the collation sequence was
** registered.  The application defined collation routine should
** return negative, zero or positive if the first string is less than,
** equal to, or greater than the second string. i.e. (STRING1 - STRING2).
**
** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
** except that it takes an extra argument which is a destructor for
** the collation.  ^The destructor is called when the collation is
** destroyed and is passed a copy of the fourth parameter void* pointer
** of the sqlite3_create_collation_v2().
** ^Collations are destroyed when they are overridden by later calls to the
** collation creation functions or when the [database connection] is closed
** using [sqlite3_close()].
**
** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
*/
SQLITE_API int sqlite3_create_collation(
  sqlite3*,
  const char *zName,
  int eTextRep,
  void*,
  int(*xCompare)(void*,int,const void*,int,const void*)
);
SQLITE_API int sqlite3_create_collation_v2(
  sqlite3*,
  const char *zName,
  int eTextRep,
  void*,
  int(*xCompare)(void*,int,const void*,int,const void*),
  void(*xDestroy)(void*)
);
SQLITE_API int sqlite3_create_collation16(
  sqlite3*,
  const void *zName,
  int eTextRep,
  void*,
  int(*xCompare)(void*,int,const void*,int,const void*)
);

/*
** CAPI3REF: Collation Needed Callbacks
**
** ^To avoid having to register all collation sequences before a database
** can be used, a single callback function may be registered with the
** [database connection] to be invoked whenever an undefined collation
** sequence is required.
**
** ^If the function is registered using the sqlite3_collation_needed() API,
** then it is passed the names of undefined collation sequences as strings
** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
** the names are passed as UTF-16 in machine native byte order.
** ^A call to either function replaces the existing collation-needed callback.
**
** ^(When the callback is invoked, the first argument passed is a copy
** of the second argument to sqlite3_collation_needed() or
** sqlite3_collation_needed16().  The second argument is the database
** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
** sequence function required.  The fourth parameter is the name of the
** required collation sequence.)^
**
** The callback function should register the desired collation using
** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
** [sqlite3_create_collation_v2()].
*/
SQLITE_API int sqlite3_collation_needed(
  sqlite3*,
  void*,
  void(*)(void*,sqlite3*,int eTextRep,const char*)
);
SQLITE_API int sqlite3_collation_needed16(
  sqlite3*,
  void*,
  void(*)(void*,sqlite3*,int eTextRep,const void*)
);

/*
** Specify the key for an encrypted database.  This routine should be
** called right after sqlite3_open().
**
** The code to implement this API is not available in the public release
** of SQLite.
*/
SQLITE_API int sqlite3_key(
  sqlite3 *db,                   /* Database to be rekeyed */
  const void *pKey, int nKey     /* The key */
);

/*
** Change the key on an open database.  If the current database is not
** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
** database is decrypted.
**
** The code to implement this API is not available in the public release
** of SQLite.
*/
SQLITE_API int sqlite3_rekey(
  sqlite3 *db,                   /* Database to be rekeyed */
  const void *pKey, int nKey     /* The new key */
);

/*
** CAPI3REF: Suspend Execution For A Short Time
**
** ^The sqlite3_sleep() function causes the current thread to suspend execution
** for at least a number of milliseconds specified in its parameter.
**
** ^If the operating system does not support sleep requests with
** millisecond time resolution, then the time will be rounded up to
** the nearest second. ^The number of milliseconds of sleep actually
** requested from the operating system is returned.
**
** ^SQLite implements this interface by calling the xSleep()
** method of the default [sqlite3_vfs] object.
*/
SQLITE_API int sqlite3_sleep(int);

/*
** CAPI3REF: Name Of The Folder Holding Temporary Files
**
** ^(If this global variable is made to point to a string which is
** the name of a folder (a.k.a. directory), then all temporary files
** created by SQLite when using a built-in [sqlite3_vfs | VFS]
** will be placed in that directory.)^  ^If this variable
** is a NULL pointer, then SQLite performs a search for an appropriate
** temporary file directory.
**
** It is not safe to read or modify this variable in more than one
** thread at a time.  It is not safe to read or modify this variable
** if a [database connection] is being used at the same time in a separate
** thread.
** It is intended that this variable be set once
** as part of process initialization and before any SQLite interface
** routines have been called and that this variable remain unchanged
** thereafter.
**
** ^The [temp_store_directory pragma] may modify this variable and cause
** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
** the [temp_store_directory pragma] always assumes that any string
** that this variable points to is held in memory obtained from
** [sqlite3_malloc] and the pragma may attempt to free that memory
** using [sqlite3_free].
** Hence, if this variable is modified directly, either it should be
** made NULL or made to point to memory obtained from [sqlite3_malloc]
** or else the use of the [temp_store_directory pragma] should be avoided.
*/
SQLITE_API char *sqlite3_temp_directory;

/*
** CAPI3REF: Test For Auto-Commit Mode
** KEYWORDS: {autocommit mode}
**
** ^The sqlite3_get_autocommit() interface returns non-zero or
** zero if the given database connection is or is not in autocommit mode,
** respectively.  ^Autocommit mode is on by default.
** ^Autocommit mode is disabled by a [BEGIN] statement.
** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
**
** If certain kinds of errors occur on a statement within a multi-statement
** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
** transaction might be rolled back automatically.  The only way to
** find out whether SQLite automatically rolled back the transaction after
** an error is to use this function.
**
** If another thread changes the autocommit status of the database
** connection while this routine is running, then the return value
** is undefined.
*/
SQLITE_API int sqlite3_get_autocommit(sqlite3*);

/*
** CAPI3REF: Find The Database Handle Of A Prepared Statement
**
** ^The sqlite3_db_handle interface returns the [database connection] handle
** to which a [prepared statement] belongs.  ^The [database connection]
** returned by sqlite3_db_handle is the same [database connection]
** that was the first argument
** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
** create the statement in the first place.
*/
SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);

/*
** CAPI3REF: Find the next prepared statement
**
** ^This interface returns a pointer to the next [prepared statement] after
** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
** then this interface returns a pointer to the first prepared statement
** associated with the database connection pDb.  ^If no prepared statement
** satisfies the conditions of this routine, it returns NULL.
**
** The [database connection] pointer D in a call to
** [sqlite3_next_stmt(D,S)] must refer to an open database
** connection and in particular must not be a NULL pointer.
*/
SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);

/*
** CAPI3REF: Commit And Rollback Notification Callbacks
**
** ^The sqlite3_commit_hook() interface registers a callback
** function to be invoked whenever a transaction is [COMMIT | committed].
** ^Any callback set by a previous call to sqlite3_commit_hook()
** for the same database connection is overridden.
** ^The sqlite3_rollback_hook() interface registers a callback
** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
** ^Any callback set by a previous call to sqlite3_rollback_hook()
** for the same database connection is overridden.
** ^The pArg argument is passed through to the callback.
** ^If the callback on a commit hook function returns non-zero,
** then the commit is converted into a rollback.
**
** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
** return the P argument from the previous call of the same function
** on the same [database connection] D, or NULL for
** the first call for each function on D.
**
** The callback implementation must not do anything that will modify
** the database connection that invoked the callback.  Any actions
** to modify the database connection must be deferred until after the
** completion of the [sqlite3_step()] call that triggered the commit
** or rollback hook in the first place.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** ^Registering a NULL function disables the callback.
**
** ^When the commit hook callback routine returns zero, the [COMMIT]
** operation is allowed to continue normally.  ^If the commit hook
** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
** ^The rollback hook is invoked on a rollback that results from a commit
** hook returning non-zero, just as it would be with any other rollback.
**
** ^For the purposes of this API, a transaction is said to have been
** rolled back if an explicit "ROLLBACK" statement is executed, or
** an error or constraint causes an implicit rollback to occur.
** ^The rollback callback is not invoked if a transaction is
** automatically rolled back because the database connection is closed.
** ^The rollback callback is not invoked if a transaction is
** rolled back because a commit callback returned non-zero.
**
** See also the [sqlite3_update_hook()] interface.
*/
SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);

/*
** CAPI3REF: Data Change Notification Callbacks
**
** ^The sqlite3_update_hook() interface registers a callback function
** with the [database connection] identified by the first argument
** to be invoked whenever a row is updated, inserted or deleted.
** ^Any callback set by a previous call to this function
** for the same database connection is overridden.
**
** ^The second argument is a pointer to the function to invoke when a
** row is updated, inserted or deleted.
** ^The first argument to the callback is a copy of the third argument
** to sqlite3_update_hook().
** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
** or [SQLITE_UPDATE], depending on the operation that caused the callback
** to be invoked.
** ^The third and fourth arguments to the callback contain pointers to the
** database and table name containing the affected row.
** ^The final callback parameter is the [rowid] of the row.
** ^In the case of an update, this is the [rowid] after the update takes place.
**
** ^(The update hook is not invoked when internal system tables are
** modified (i.e. sqlite_master and sqlite_sequence).)^
**
** ^In the current implementation, the update hook
** is not invoked when duplication rows are deleted because of an
** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
** invoked when rows are deleted using the [truncate optimization].
** The exceptions defined in this paragraph might change in a future
** release of SQLite.
**
** The update hook implementation must not do anything that will modify
** the database connection that invoked the update hook.  Any actions
** to modify the database connection must be deferred until after the
** completion of the [sqlite3_step()] call that triggered the update hook.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** ^The sqlite3_update_hook(D,C,P) function
** returns the P argument from the previous call
** on the same [database connection] D, or NULL for
** the first call on D.
**
** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
** interfaces.
*/
SQLITE_API void *sqlite3_update_hook(
  sqlite3*,
  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  void*
);

/*
** CAPI3REF: Enable Or Disable Shared Pager Cache
** KEYWORDS: {shared cache}
**
** ^(This routine enables or disables the sharing of the database cache
** and schema data structures between [database connection | connections]
** to the same database. Sharing is enabled if the argument is true
** and disabled if the argument is false.)^
**
** ^Cache sharing is enabled and disabled for an entire process.
** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
** sharing was enabled or disabled for each thread separately.
**
** ^(The cache sharing mode set by this interface effects all subsequent
** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
** Existing database connections continue use the sharing mode
** that was in effect at the time they were opened.)^
**
** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
** successfully.  An [error code] is returned otherwise.)^
**
** ^Shared cache is disabled by default. But this might change in
** future releases of SQLite.  Applications that care about shared
** cache setting should set it explicitly.
**
** See Also:  [SQLite Shared-Cache Mode]
*/
SQLITE_API int sqlite3_enable_shared_cache(int);

/*
** CAPI3REF: Attempt To Free Heap Memory
**
** ^The sqlite3_release_memory() interface attempts to free N bytes
** of heap memory by deallocating non-essential memory allocations
** held by the database library.   Memory used to cache database
** pages to improve performance is an example of non-essential memory.
** ^sqlite3_release_memory() returns the number of bytes actually freed,
** which might be more or less than the amount requested.
*/
SQLITE_API int sqlite3_release_memory(int);

/*
** CAPI3REF: Impose A Limit On Heap Size
**
** ^The sqlite3_soft_heap_limit() interface places a "soft" limit
** on the amount of heap memory that may be allocated by SQLite.
** ^If an internal allocation is requested that would exceed the
** soft heap limit, [sqlite3_release_memory()] is invoked one or
** more times to free up some space before the allocation is performed.
**
** ^The limit is called "soft" because if [sqlite3_release_memory()]
** cannot free sufficient memory to prevent the limit from being exceeded,
** the memory is allocated anyway and the current operation proceeds.
**
** ^A negative or zero value for N means that there is no soft heap limit and
** [sqlite3_release_memory()] will only be called when memory is exhausted.
** ^The default value for the soft heap limit is zero.
**
** ^(SQLite makes a best effort to honor the soft heap limit.
** But if the soft heap limit cannot be honored, execution will
** continue without error or notification.)^  This is why the limit is
** called a "soft" limit.  It is advisory only.
**
** Prior to SQLite version 3.5.0, this routine only constrained the memory
** allocated by a single thread - the same thread in which this routine
** runs.  Beginning with SQLite version 3.5.0, the soft heap limit is
** applied to all threads. The value specified for the soft heap limit
** is an upper bound on the total memory allocation for all threads. In
** version 3.5.0 there is no mechanism for limiting the heap usage for
** individual threads.
*/
SQLITE_API void sqlite3_soft_heap_limit(int);

/*
** CAPI3REF: Extract Metadata About A Column Of A Table
**
** ^This routine returns metadata about a specific column of a specific
** database table accessible using the [database connection] handle
** passed as the first function argument.
**
** ^The column is identified by the second, third and fourth parameters to
** this function. ^The second parameter is either the name of the database
** (i.e. "main", "temp", or an attached database) containing the specified
** table or NULL. ^If it is NULL, then all attached databases are searched
** for the table using the same algorithm used by the database engine to
** resolve unqualified table references.
**
** ^The third and fourth parameters to this function are the table and column
** name of the desired column, respectively. Neither of these parameters
** may be NULL.
**
** ^Metadata is returned by writing to the memory locations passed as the 5th
** and subsequent parameters to this function. ^Any of these arguments may be
** NULL, in which case the corresponding element of metadata is omitted.
**
** ^(<blockquote>
** <table border="1">
** <tr><th> Parameter <th> Output<br>Type <th>  Description
**
** <tr><td> 5th <td> const char* <td> Data type
** <tr><td> 6th <td> const char* <td> Name of default collation sequence
** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
** </table>
** </blockquote>)^
**
** ^The memory pointed to by the character pointers returned for the
** declaration type and collation sequence is valid only until the next
** call to any SQLite API function.
**
** ^If the specified table is actually a view, an [error code] is returned.
**
** ^If the specified column is "rowid", "oid" or "_rowid_" and an
** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
** parameters are set for the explicitly declared column. ^(If there is no
** explicitly declared [INTEGER PRIMARY KEY] column, then the output
** parameters are set as follows:
**
** <pre>
**     data type: "INTEGER"
**     collation sequence: "BINARY"
**     not null: 0
**     primary key: 1
**     auto increment: 0
** </pre>)^
**
** ^(This function may load one or more schemas from database files. If an
** error occurs during this process, or if the requested table or column
** cannot be found, an [error code] is returned and an error message left
** in the [database connection] (to be retrieved using sqlite3_errmsg()).)^
**
** ^This API is only available if the library was compiled with the
** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
*/
SQLITE_API int sqlite3_table_column_metadata(
  sqlite3 *db,                /* Connection handle */
  const char *zDbName,        /* Database name or NULL */
  const char *zTableName,     /* Table name */
  const char *zColumnName,    /* Column name */
  char const **pzDataType,    /* OUTPUT: Declared data type */
  char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
  int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
  int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
  int *pAutoinc               /* OUTPUT: True if column is auto-increment */
);

/*
** CAPI3REF: Load An Extension
**
** ^This interface loads an SQLite extension library from the named file.
**
** ^The sqlite3_load_extension() interface attempts to load an
** SQLite extension library contained in the file zFile.
**
** ^The entry point is zProc.
** ^zProc may be 0, in which case the name of the entry point
** defaults to "sqlite3_extension_init".
** ^The sqlite3_load_extension() interface returns
** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
** ^If an error occurs and pzErrMsg is not 0, then the
** [sqlite3_load_extension()] interface shall attempt to
** fill *pzErrMsg with error message text stored in memory
** obtained from [sqlite3_malloc()]. The calling function
** should free this memory by calling [sqlite3_free()].
**
** ^Extension loading must be enabled using
** [sqlite3_enable_load_extension()] prior to calling this API,
** otherwise an error will be returned.
**
** See also the [load_extension() SQL function].
*/
SQLITE_API int sqlite3_load_extension(
  sqlite3 *db,          /* Load the extension into this database connection */
  const char *zFile,    /* Name of the shared library containing extension */
  const char *zProc,    /* Entry point.  Derived from zFile if 0 */
  char **pzErrMsg       /* Put error message here if not 0 */
);

/*
** CAPI3REF: Enable Or Disable Extension Loading
**
** ^So as not to open security holes in older applications that are
** unprepared to deal with extension loading, and as a means of disabling
** extension loading while evaluating user-entered SQL, the following API
** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
**
** ^Extension loading is off by default. See ticket #1863.
** ^Call the sqlite3_enable_load_extension() routine with onoff==1
** to turn extension loading on and call it with onoff==0 to turn
** it back off again.
*/
SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);

/*
** CAPI3REF: Automatically Load An Extensions
**
** ^This API can be invoked at program startup in order to register
** one or more statically linked extensions that will be available
** to all new [database connections].
**
** ^(This routine stores a pointer to the extension entry point
** in an array that is obtained from [sqlite3_malloc()].  That memory
** is deallocated by [sqlite3_reset_auto_extension()].)^
**
** ^This function registers an extension entry point that is
** automatically invoked whenever a new [database connection]
** is opened using [sqlite3_open()], [sqlite3_open16()],
** or [sqlite3_open_v2()].
** ^Duplicate extensions are detected so calling this routine
** multiple times with the same extension is harmless.
** ^Automatic extensions apply across all threads.
*/
SQLITE_API int sqlite3_auto_extension(void (*xEntryPoint)(void));

/*
** CAPI3REF: Reset Automatic Extension Loading
**
** ^(This function disables all previously registered automatic
** extensions. It undoes the effect of all prior
** [sqlite3_auto_extension()] calls.)^
**
** ^This function disables automatic extensions in all threads.
*/
SQLITE_API void sqlite3_reset_auto_extension(void);

/*
****** EXPERIMENTAL - subject to change without notice **************
**
** The interface to the virtual-table mechanism is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stabilizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.
*/

/*
** Structures used by the virtual table interface
*/
typedef struct sqlite3_vtab sqlite3_vtab;
typedef struct sqlite3_index_info sqlite3_index_info;
typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
typedef struct sqlite3_module sqlite3_module;

/*
** CAPI3REF: Virtual Table Object
** KEYWORDS: sqlite3_module {virtual table module}
** EXPERIMENTAL
**
** This structure, sometimes called a a "virtual table module",
** defines the implementation of a [virtual tables].
** This structure consists mostly of methods for the module.
**
** ^A virtual table module is created by filling in a persistent
** instance of this structure and passing a pointer to that instance
** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
** ^The registration remains valid until it is replaced by a different
** module or until the [database connection] closes.  The content
** of this structure must not change while it is registered with
** any database connection.
*/
struct sqlite3_module {
  int iVersion;
  int (*xCreate)(sqlite3*, void *pAux,
               int argc, const char *const*argv,
               sqlite3_vtab **ppVTab, char**);
  int (*xConnect)(sqlite3*, void *pAux,
               int argc, const char *const*argv,
               sqlite3_vtab **ppVTab, char**);
  int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
  int (*xDisconnect)(sqlite3_vtab *pVTab);
  int (*xDestroy)(sqlite3_vtab *pVTab);
  int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
  int (*xClose)(sqlite3_vtab_cursor*);
  int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
                int argc, sqlite3_value **argv);
  int (*xNext)(sqlite3_vtab_cursor*);
  int (*xEof)(sqlite3_vtab_cursor*);
  int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
  int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
  int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
  int (*xBegin)(sqlite3_vtab *pVTab);
  int (*xSync)(sqlite3_vtab *pVTab);
  int (*xCommit)(sqlite3_vtab *pVTab);
  int (*xRollback)(sqlite3_vtab *pVTab);
  int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
                       void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
                       void **ppArg);
  int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
};

/*
** CAPI3REF: Virtual Table Indexing Information
** KEYWORDS: sqlite3_index_info
** EXPERIMENTAL
**
** The sqlite3_index_info structure and its substructures is used to
** pass information into and receive the reply from the [xBestIndex]
** method of a [virtual table module].  The fields under **Inputs** are the
** inputs to xBestIndex and are read-only.  xBestIndex inserts its
** results into the **Outputs** fields.
**
** ^(The aConstraint[] array records WHERE clause constraints of the form:
**
** <pre>column OP expr</pre>
**
** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^  ^(The particular operator is
** stored in aConstraint[].op.)^  ^(The index of the column is stored in
** aConstraint[].iColumn.)^  ^(aConstraint[].usable is TRUE if the
** expr on the right-hand side can be evaluated (and thus the constraint
** is usable) and false if it cannot.)^
**
** ^The optimizer automatically inverts terms of the form "expr OP column"
** and makes other simplifications to the WHERE clause in an attempt to
** get as many WHERE clause terms into the form shown above as possible.
** ^The aConstraint[] array only reports WHERE clause terms that are
** relevant to the particular virtual table being queried.
**
** ^Information about the ORDER BY clause is stored in aOrderBy[].
** ^Each term of aOrderBy records a column of the ORDER BY clause.
**
** The [xBestIndex] method must fill aConstraintUsage[] with information
** about what parameters to pass to xFilter.  ^If argvIndex>0 then
** the right-hand side of the corresponding aConstraint[] is evaluated
** and becomes the argvIndex-th entry in argv.  ^(If aConstraintUsage[].omit
** is true, then the constraint is assumed to be fully handled by the
** virtual table and is not checked again by SQLite.)^
**
** ^The idxNum and idxPtr values are recorded and passed into the
** [xFilter] method.
** ^[sqlite3_free()] is used to free idxPtr if and only if
** needToFreeIdxPtr is true.
**
** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
** the correct order to satisfy the ORDER BY clause so that no separate
** sorting step is required.
**
** ^The estimatedCost value is an estimate of the cost of doing the
** particular lookup.  A full scan of a table with N entries should have
** a cost of N.  A binary search of a table of N entries should have a
** cost of approximately log(N).
*/
struct sqlite3_index_info {
  /* Inputs */
  int nConstraint;           /* Number of entries in aConstraint */
  struct sqlite3_index_constraint {
     int iColumn;              /* Column on left-hand side of constraint */
     unsigned char op;         /* Constraint operator */
     unsigned char usable;     /* True if this constraint is usable */
     int iTermOffset;          /* Used internally - xBestIndex should ignore */
  } *aConstraint;            /* Table of WHERE clause constraints */
  int nOrderBy;              /* Number of terms in the ORDER BY clause */
  struct sqlite3_index_orderby {
     int iColumn;              /* Column number */
     unsigned char desc;       /* True for DESC.  False for ASC. */
  } *aOrderBy;               /* The ORDER BY clause */
  /* Outputs */
  struct sqlite3_index_constraint_usage {
    int argvIndex;           /* if >0, constraint is part of argv to xFilter */
    unsigned char omit;      /* Do not code a test for this constraint */
  } *aConstraintUsage;
  int idxNum;                /* Number used to identify the index */
  char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
  int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
  int orderByConsumed;       /* True if output is already ordered */
  double estimatedCost;      /* Estimated cost of using this index */
};
#define SQLITE_INDEX_CONSTRAINT_EQ    2
#define SQLITE_INDEX_CONSTRAINT_GT    4
#define SQLITE_INDEX_CONSTRAINT_LE    8
#define SQLITE_INDEX_CONSTRAINT_LT    16
#define SQLITE_INDEX_CONSTRAINT_GE    32
#define SQLITE_INDEX_CONSTRAINT_MATCH 64

/*
** CAPI3REF: Register A Virtual Table Implementation
** EXPERIMENTAL
**
** ^These routines are used to register a new [virtual table module] name.
** ^Module names must be registered before
** creating a new [virtual table] using the module and before using a
** preexisting [virtual table] for the module.
**
** ^The module name is registered on the [database connection] specified
** by the first parameter.  ^The name of the module is given by the
** second parameter.  ^The third parameter is a pointer to
** the implementation of the [virtual table module].   ^The fourth
** parameter is an arbitrary client data pointer that is passed through
** into the [xCreate] and [xConnect] methods of the virtual table module
** when a new virtual table is be being created or reinitialized.
**
** ^The sqlite3_create_module_v2() interface has a fifth parameter which
** is a pointer to a destructor for the pClientData.  ^SQLite will
** invoke the destructor function (if it is not NULL) when SQLite
** no longer needs the pClientData pointer.  ^The sqlite3_create_module()
** interface is equivalent to sqlite3_create_module_v2() with a NULL
** destructor.
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_create_module(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *p,   /* Methods for the module */
  void *pClientData          /* Client data for xCreate/xConnect */
);
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_create_module_v2(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *p,   /* Methods for the module */
  void *pClientData,         /* Client data for xCreate/xConnect */
  void(*xDestroy)(void*)     /* Module destructor function */
);

/*
** CAPI3REF: Virtual Table Instance Object
** KEYWORDS: sqlite3_vtab
** EXPERIMENTAL
**
** Every [virtual table module] implementation uses a subclass
** of this object to describe a particular instance
** of the [virtual table].  Each subclass will
** be tailored to the specific needs of the module implementation.
** The purpose of this superclass is to define certain fields that are
** common to all module implementations.
**
** ^Virtual tables methods can set an error message by assigning a
** string obtained from [sqlite3_mprintf()] to zErrMsg.  The method should
** take care that any prior string is freed by a call to [sqlite3_free()]
** prior to assigning a new string to zErrMsg.  ^After the error message
** is delivered up to the client application, the string will be automatically
** freed by sqlite3_free() and the zErrMsg field will be zeroed.
*/
struct sqlite3_vtab {
  const sqlite3_module *pModule;  /* The module for this virtual table */
  int nRef;                       /* NO LONGER USED */
  char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
  /* Virtual table implementations will typically add additional fields */
};

/*
** CAPI3REF: Virtual Table Cursor Object
** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
** EXPERIMENTAL
**
** Every [virtual table module] implementation uses a subclass of the
** following structure to describe cursors that point into the
** [virtual table] and are used
** to loop through the virtual table.  Cursors are created using the
** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
** by the [sqlite3_module.xClose | xClose] method.  Cursors are used
** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
** of the module.  Each module implementation will define
** the content of a cursor structure to suit its own needs.
**
** This superclass exists in order to define fields of the cursor that
** are common to all implementations.
*/
struct sqlite3_vtab_cursor {
  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
  /* Virtual table implementations will typically add additional fields */
};

/*
** CAPI3REF: Declare The Schema Of A Virtual Table
** EXPERIMENTAL
**
** ^The [xCreate] and [xConnect] methods of a
** [virtual table module] call this interface
** to declare the format (the names and datatypes of the columns) of
** the virtual tables they implement.
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_declare_vtab(sqlite3*, const char *zSQL);

/*
** CAPI3REF: Overload A Function For A Virtual Table
** EXPERIMENTAL
**
** ^(Virtual tables can provide alternative implementations of functions
** using the [xFindFunction] method of the [virtual table module].
** But global versions of those functions
** must exist in order to be overloaded.)^
**
** ^(This API makes sure a global version of a function with a particular
** name and number of parameters exists.  If no such function exists
** before this API is called, a new function is created.)^  ^The implementation
** of the new function always causes an exception to be thrown.  So
** the new function is not good for anything by itself.  Its only
** purpose is to be a placeholder function that can be overloaded
** by a [virtual table].
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);

/*
** The interface to the virtual-table mechanism defined above (back up
** to a comment remarkably similar to this one) is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stabilizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.
**
****** EXPERIMENTAL - subject to change without notice **************
*/

/*
** CAPI3REF: A Handle To An Open BLOB
** KEYWORDS: {BLOB handle} {BLOB handles}
**
** An instance of this object represents an open BLOB on which
** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
** ^Objects of this type are created by [sqlite3_blob_open()]
** and destroyed by [sqlite3_blob_close()].
** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
** can be used to read or write small subsections of the BLOB.
** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
*/
typedef struct sqlite3_blob sqlite3_blob;

/*
** CAPI3REF: Open A BLOB For Incremental I/O
**
** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
** in row iRow, column zColumn, table zTable in database zDb;
** in other words, the same BLOB that would be selected by:
**
** <pre>
**     SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
** </pre>)^
**
** ^If the flags parameter is non-zero, then the BLOB is opened for read
** and write access. ^If it is zero, the BLOB is opened for read access.
** ^It is not possible to open a column that is part of an index or primary
** key for writing. ^If [foreign key constraints] are enabled, it is
** not possible to open a column that is part of a [child key] for writing.
**
** ^Note that the database name is not the filename that contains
** the database but rather the symbolic name of the database that
** appears after the AS keyword when the database is connected using [ATTACH].
** ^For the main database file, the database name is "main".
** ^For TEMP tables, the database name is "temp".
**
** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
** to *ppBlob. Otherwise an [error code] is returned and *ppBlob is set
** to be a null pointer.)^
** ^This function sets the [database connection] error code and message
** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related
** functions. ^Note that the *ppBlob variable is always initialized in a
** way that makes it safe to invoke [sqlite3_blob_close()] on *ppBlob
** regardless of the success or failure of this routine.
**
** ^(If the row that a BLOB handle points to is modified by an
** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
** then the BLOB handle is marked as "expired".
** This is true if any column of the row is changed, even a column
** other than the one the BLOB handle is open on.)^
** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
** a expired BLOB handle fail with an return code of [SQLITE_ABORT].
** ^(Changes written into a BLOB prior to the BLOB expiring are not
** rolled back by the expiration of the BLOB.  Such changes will eventually
** commit if the transaction continues to completion.)^
**
** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
** the opened blob.  ^The size of a blob may not be changed by this
** interface.  Use the [UPDATE] SQL command to change the size of a
** blob.
**
** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
** and the built-in [zeroblob] SQL function can be used, if desired,
** to create an empty, zero-filled blob in which to read or write using
** this interface.
**
** To avoid a resource leak, every open [BLOB handle] should eventually
** be released by a call to [sqlite3_blob_close()].
*/
SQLITE_API int sqlite3_blob_open(
  sqlite3*,
  const char *zDb,
  const char *zTable,
  const char *zColumn,
  sqlite3_int64 iRow,
  int flags,
  sqlite3_blob **ppBlob
);

/*
** CAPI3REF: Close A BLOB Handle
**
** ^Closes an open [BLOB handle].
**
** ^Closing a BLOB shall cause the current transaction to commit
** if there are no other BLOBs, no pending prepared statements, and the
** database connection is in [autocommit mode].
** ^If any writes were made to the BLOB, they might be held in cache
** until the close operation if they will fit.
**
** ^(Closing the BLOB often forces the changes
** out to disk and so if any I/O errors occur, they will likely occur
** at the time when the BLOB is closed.  Any errors that occur during
** closing are reported as a non-zero return value.)^
**
** ^(The BLOB is closed unconditionally.  Even if this routine returns
** an error code, the BLOB is still closed.)^
**
** ^Calling this routine with a null pointer (such as would be returned
** by a failed call to [sqlite3_blob_open()]) is a harmless no-op.
*/
SQLITE_API int sqlite3_blob_close(sqlite3_blob *);

/*
** CAPI3REF: Return The Size Of An Open BLOB
**
** ^Returns the size in bytes of the BLOB accessible via the
** successfully opened [BLOB handle] in its only argument.  ^The
** incremental blob I/O routines can only read or overwriting existing
** blob content; they cannot change the size of a blob.
**
** This routine only works on a [BLOB handle] which has been created
** by a prior successful call to [sqlite3_blob_open()] and which has not
** been closed by [sqlite3_blob_close()].  Passing any other pointer in
** to this routine results in undefined and probably undesirable behavior.
*/
SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *);

/*
** CAPI3REF: Read Data From A BLOB Incrementally
**
** ^(This function is used to read data from an open [BLOB handle] into a
** caller-supplied buffer. N bytes of data are copied into buffer Z
** from the open BLOB, starting at offset iOffset.)^
**
** ^If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is read.  ^If N or iOffset is
** less than zero, [SQLITE_ERROR] is returned and no data is read.
** ^The size of the blob (and hence the maximum value of N+iOffset)
** can be determined using the [sqlite3_blob_bytes()] interface.
**
** ^An attempt to read from an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].
**
** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
** Otherwise, an [error code] or an [extended error code] is returned.)^
**
** This routine only works on a [BLOB handle] which has been created
** by a prior successful call to [sqlite3_blob_open()] and which has not
** been closed by [sqlite3_blob_close()].  Passing any other pointer in
** to this routine results in undefined and probably undesirable behavior.
**
** See also: [sqlite3_blob_write()].
*/
SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);

/*
** CAPI3REF: Write Data Into A BLOB Incrementally
**
** ^This function is used to write data into an open [BLOB handle] from a
** caller-supplied buffer. ^N bytes of data are copied from the buffer Z
** into the open BLOB, starting at offset iOffset.
**
** ^If the [BLOB handle] passed as the first argument was not opened for
** writing (the flags parameter to [sqlite3_blob_open()] was zero),
** this function returns [SQLITE_READONLY].
**
** ^This function may only modify the contents of the BLOB; it is
** not possible to increase the size of a BLOB using this API.
** ^If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is written.  ^If N is
** less than zero [SQLITE_ERROR] is returned and no data is written.
** The size of the BLOB (and hence the maximum value of N+iOffset)
** can be determined using the [sqlite3_blob_bytes()] interface.
**
** ^An attempt to write to an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].  ^Writes to the BLOB that occurred
** before the [BLOB handle] expired are not rolled back by the
** expiration of the handle, though of course those changes might
** have been overwritten by the statement that expired the BLOB handle
** or by other independent statements.
**
** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
** Otherwise, an  [error code] or an [extended error code] is returned.)^
**
** This routine only works on a [BLOB handle] which has been created
** by a prior successful call to [sqlite3_blob_open()] and which has not
** been closed by [sqlite3_blob_close()].  Passing any other pointer in
** to this routine results in undefined and probably undesirable behavior.
**
** See also: [sqlite3_blob_read()].
*/
SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);

/*
** CAPI3REF: Virtual File System Objects
**
** A virtual filesystem (VFS) is an [sqlite3_vfs] object
** that SQLite uses to interact
** with the underlying operating system.  Most SQLite builds come with a
** single default VFS that is appropriate for the host computer.
** New VFSes can be registered and existing VFSes can be unregistered.
** The following interfaces are provided.
**
** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
** ^Names are case sensitive.
** ^Names are zero-terminated UTF-8 strings.
** ^If there is no match, a NULL pointer is returned.
** ^If zVfsName is NULL then the default VFS is returned.
**
** ^New VFSes are registered with sqlite3_vfs_register().
** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
** ^The same VFS can be registered multiple times without injury.
** ^To make an existing VFS into the default VFS, register it again
** with the makeDflt flag set.  If two different VFSes with the
** same name are registered, the behavior is undefined.  If a
** VFS is registered with a name that is NULL or an empty string,
** then the behavior is undefined.
**
** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
** ^(If the default VFS is unregistered, another VFS is chosen as
** the default.  The choice for the new VFS is arbitrary.)^
*/
SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*);

/*
** CAPI3REF: Mutexes
**
** The SQLite core uses these routines for thread
** synchronization. Though they are intended for internal
** use by SQLite, code that links against SQLite is
** permitted to use any of these routines.
**
** The SQLite source code contains multiple implementations
** of these mutex routines.  An appropriate implementation
** is selected automatically at compile-time.  ^(The following
** implementations are available in the SQLite core:
**
** <ul>
** <li>   SQLITE_MUTEX_OS2
** <li>   SQLITE_MUTEX_PTHREAD
** <li>   SQLITE_MUTEX_W32
** <li>   SQLITE_MUTEX_NOOP
** </ul>)^
**
** ^The SQLITE_MUTEX_NOOP implementation is a set of routines
** that does no real locking and is appropriate for use in
** a single-threaded application.  ^The SQLITE_MUTEX_OS2,
** SQLITE_MUTEX_PTHREAD, and SQLITE_MUTEX_W32 implementations
** are appropriate for use on OS/2, Unix, and Windows.
**
** ^(If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
** implementation is included with the library. In this case the
** application must supply a custom mutex implementation using the
** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
** before calling sqlite3_initialize() or any other public sqlite3_
** function that calls sqlite3_initialize().)^
**
** ^The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it. ^If it returns NULL
** that means that a mutex could not be allocated.  ^SQLite
** will unwind its stack and return an error.  ^(The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li>  SQLITE_MUTEX_FAST
** <li>  SQLITE_MUTEX_RECURSIVE
** <li>  SQLITE_MUTEX_STATIC_MASTER
** <li>  SQLITE_MUTEX_STATIC_MEM
** <li>  SQLITE_MUTEX_STATIC_MEM2
** <li>  SQLITE_MUTEX_STATIC_PRNG
** <li>  SQLITE_MUTEX_STATIC_LRU
** <li>  SQLITE_MUTEX_STATIC_LRU2
** </ul>)^
**
** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
** cause sqlite3_mutex_alloc() to create
** a new mutex.  ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
** not want to.  ^SQLite will only request a recursive mutex in
** cases where it really needs one.  ^If a faster non-recursive mutex
** implementation is available on the host platform, the mutex subsystem
** might return such a mutex in response to SQLITE_MUTEX_FAST.
**
** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return
** a pointer to a static preexisting mutex.  ^Six static mutexes are
** used by the current version of SQLite.  Future versions of SQLite
** may add additional static mutexes.  Static mutexes are for internal
** use by SQLite only.  Applications that use SQLite mutexes should
** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
** SQLITE_MUTEX_RECURSIVE.
**
** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
** returns a different mutex on every call.  ^But for the static
** mutex types, the same mutex is returned on every call that has
** the same type number.
**
** ^The sqlite3_mutex_free() routine deallocates a previously
** allocated dynamic mutex.  ^SQLite is careful to deallocate every
** dynamic mutex that it allocates.  The dynamic mutexes must not be in
** use when they are deallocated.  Attempting to deallocate a static
** mutex results in undefined behavior.  ^SQLite never deallocates
** a static mutex.
**
** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  ^If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY.  ^The sqlite3_mutex_try() interface returns [SQLITE_OK]
** upon successful entry.  ^(Mutexes created using
** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
** In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.)^  ^(If the same thread tries to enter any other
** kind of mutex more than once, the behavior is undefined.
** SQLite will never exhibit
** such behavior in its own use of mutexes.)^
**
** ^(Some systems (for example, Windows 95) do not support the operation
** implemented by sqlite3_mutex_try().  On those systems, sqlite3_mutex_try()
** will always return SQLITE_BUSY.  The SQLite core only ever uses
** sqlite3_mutex_try() as an optimization so this is acceptable behavior.)^
**
** ^The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.   ^(The behavior
** is undefined if the mutex is not currently entered by the
** calling thread or is not currently allocated.  SQLite will
** never do either.)^
**
** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
** sqlite3_mutex_leave() is a NULL pointer, then all three routines
** behave as no-ops.
**
** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
*/
SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int);
SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*);
SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*);
SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*);
SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*);

/*
** CAPI3REF: Mutex Methods Object
** EXPERIMENTAL
**
** An instance of this structure defines the low-level routines
** used to allocate and use mutexes.
**
** Usually, the default mutex implementations provided by SQLite are
** sufficient, however the user has the option of substituting a custom
** implementation for specialized deployments or systems for which SQLite
** does not provide a suitable implementation. In this case, the user
** creates and populates an instance of this structure to pass
** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
** Additionally, an instance of this structure can be used as an
** output variable when querying the system for the current mutex
** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
**
** ^The xMutexInit method defined by this structure is invoked as
** part of system initialization by the sqlite3_initialize() function.
** ^The xMutexInit routine is calle by SQLite exactly once for each
** effective call to [sqlite3_initialize()].
**
** ^The xMutexEnd method defined by this structure is invoked as
** part of system shutdown by the sqlite3_shutdown() function. The
** implementation of this method is expected to release all outstanding
** resources obtained by the mutex methods implementation, especially
** those obtained by the xMutexInit method.  ^The xMutexEnd()
** interface is invoked exactly once for each call to [sqlite3_shutdown()].
**
** ^(The remaining seven methods defined by this structure (xMutexAlloc,
** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
** xMutexNotheld) implement the following interfaces (respectively):
**
** <ul>
**   <li>  [sqlite3_mutex_alloc()] </li>
**   <li>  [sqlite3_mutex_free()] </li>
**   <li>  [sqlite3_mutex_enter()] </li>
**   <li>  [sqlite3_mutex_try()] </li>
**   <li>  [sqlite3_mutex_leave()] </li>
**   <li>  [sqlite3_mutex_held()] </li>
**   <li>  [sqlite3_mutex_notheld()] </li>
** </ul>)^
**
** The only difference is that the public sqlite3_XXX functions enumerated
** above silently ignore any invocations that pass a NULL pointer instead
** of a valid mutex handle. The implementations of the methods defined
** by this structure are not required to handle this case, the results
** of passing a NULL pointer instead of a valid mutex handle are undefined
** (i.e. it is acceptable to provide an implementation that segfaults if
** it is passed a NULL pointer).
**
** The xMutexInit() method must be threadsafe.  ^It must be harmless to
** invoke xMutexInit() mutiple times within the same process and without
** intervening calls to xMutexEnd().  Second and subsequent calls to
** xMutexInit() must be no-ops.
**
** ^xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()]
** and its associates).  ^Similarly, xMutexAlloc() must not use SQLite memory
** allocation for a static mutex.  ^However xMutexAlloc() may use SQLite
** memory allocation for a fast or recursive mutex.
**
** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is
** called, but only if the prior call to xMutexInit returned SQLITE_OK.
** If xMutexInit fails in any way, it is expected to clean up after itself
** prior to returning.
*/
typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;
struct sqlite3_mutex_methods {
  int (*xMutexInit)(void);
  int (*xMutexEnd)(void);
  sqlite3_mutex *(*xMutexAlloc)(int);
  void (*xMutexFree)(sqlite3_mutex *);
  void (*xMutexEnter)(sqlite3_mutex *);
  int (*xMutexTry)(sqlite3_mutex *);
  void (*xMutexLeave)(sqlite3_mutex *);
  int (*xMutexHeld)(sqlite3_mutex *);
  int (*xMutexNotheld)(sqlite3_mutex *);
};

/*
** CAPI3REF: Mutex Verification Routines
**
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
** are intended for use inside assert() statements.  ^The SQLite core
** never uses these routines except inside an assert() and applications
** are advised to follow the lead of the core.  ^The SQLite core only
** provides implementations for these routines when it is compiled
** with the SQLITE_DEBUG flag.  ^External mutex implementations
** are only required to provide these routines if SQLITE_DEBUG is
** defined and if NDEBUG is not defined.
**
** ^These routines should return true if the mutex in their argument
** is held or not held, respectively, by the calling thread.
**
** ^The implementation is not required to provided versions of these
** routines that actually work. If the implementation does not provide working
** versions of these routines, it should at least provide stubs that always
** return true so that one does not get spurious assertion failures.
**
** ^If the argument to sqlite3_mutex_held() is a NULL pointer then
** the routine should return 1.   This seems counter-intuitive since
** clearly the mutex cannot be held if it does not exist.  But the
** the reason the mutex does not exist is because the build is not
** using mutexes.  And we do not want the assert() containing the
** call to sqlite3_mutex_held() to fail, so a non-zero return is
** the appropriate thing to do.  ^The sqlite3_mutex_notheld()
** interface should also return 1 when given a NULL pointer.
*/
#ifndef NDEBUG
SQLITE_API int sqlite3_mutex_held(sqlite3_mutex*);
SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex*);
#endif

/*
** CAPI3REF: Mutex Types
**
** The [sqlite3_mutex_alloc()] interface takes a single argument
** which is one of these integer constants.
**
** The set of static mutexes may change from one SQLite release to the
** next.  Applications that override the built-in mutex logic must be
** prepared to accommodate additional static mutexes.
*/
#define SQLITE_MUTEX_FAST             0
#define SQLITE_MUTEX_RECURSIVE        1
#define SQLITE_MUTEX_STATIC_MASTER    2
#define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
#define SQLITE_MUTEX_STATIC_MEM2      4  /* NOT USED */
#define SQLITE_MUTEX_STATIC_OPEN      4  /* sqlite3BtreeOpen() */
#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_random() */
#define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
#define SQLITE_MUTEX_STATIC_LRU2      7  /* lru page list */

/*
** CAPI3REF: Retrieve the mutex for a database connection
**
** ^This interface returns a pointer the [sqlite3_mutex] object that
** serializes access to the [database connection] given in the argument
** when the [threading mode] is Serialized.
** ^If the [threading mode] is Single-thread or Multi-thread then this
** routine returns a NULL pointer.
*/
SQLITE_API sqlite3_mutex *sqlite3_db_mutex(sqlite3*);

/*
** CAPI3REF: Low-Level Control Of Database Files
**
** ^The [sqlite3_file_control()] interface makes a direct call to the
** xFileControl method for the [sqlite3_io_methods] object associated
** with a particular database identified by the second argument. ^The
** name of the database "main" for the main database or "temp" for the
** TEMP database, or the name that appears after the AS keyword for
** databases that are added using the [ATTACH] SQL command.
** ^A NULL pointer can be used in place of "main" to refer to the
** main database file.
** ^The third and fourth parameters to this routine
** are passed directly through to the second and third parameters of
** the xFileControl method.  ^The return value of the xFileControl
** method becomes the return value of this routine.
**
** ^If the second parameter (zDbName) does not match the name of any
** open database file, then SQLITE_ERROR is returned.  ^This error
** code is not remembered and will not be recalled by [sqlite3_errcode()]
** or [sqlite3_errmsg()].  The underlying xFileControl method might
** also return SQLITE_ERROR.  There is no way to distinguish between
** an incorrect zDbName and an SQLITE_ERROR return from the underlying
** xFileControl method.
**
** See also: [SQLITE_FCNTL_LOCKSTATE]
*/
SQLITE_API int sqlite3_file_control(sqlite3*, const char *zDbName, int op, void*);

/*
** CAPI3REF: Testing Interface
**
** ^The sqlite3_test_control() interface is used to read out internal
** state of SQLite and to inject faults into SQLite for testing
** purposes.  ^The first parameter is an operation code that determines
** the number, meaning, and operation of all subsequent parameters.
**
** This interface is not for use by applications.  It exists solely
** for verifying the correct operation of the SQLite library.  Depending
** on how the SQLite library is compiled, this interface might not exist.
**
** The details of the operation codes, their meanings, the parameters
** they take, and what they do are all subject to change without notice.
** Unlike most of the SQLite API, this function is not guaranteed to
** operate consistently from one release to the next.
*/
SQLITE_API int sqlite3_test_control(int op, ...);

/*
** CAPI3REF: Testing Interface Operation Codes
**
** These constants are the valid operation code parameters used
** as the first argument to [sqlite3_test_control()].
**
** These parameters and their meanings are subject to change
** without notice.  These values are for testing purposes only.
** Applications should not use any of these parameters or the
** [sqlite3_test_control()] interface.
*/
#define SQLITE_TESTCTRL_FIRST                    5
#define SQLITE_TESTCTRL_PRNG_SAVE                5
#define SQLITE_TESTCTRL_PRNG_RESTORE             6
#define SQLITE_TESTCTRL_PRNG_RESET               7
#define SQLITE_TESTCTRL_BITVEC_TEST              8
#define SQLITE_TESTCTRL_FAULT_INSTALL            9
#define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS     10
#define SQLITE_TESTCTRL_PENDING_BYTE            11
#define SQLITE_TESTCTRL_ASSERT                  12
#define SQLITE_TESTCTRL_ALWAYS                  13
#define SQLITE_TESTCTRL_RESERVE                 14
#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
#define SQLITE_TESTCTRL_ISKEYWORD               16
#define SQLITE_TESTCTRL_LAST                    16

/*
** CAPI3REF: SQLite Runtime Status
** EXPERIMENTAL
**
** ^This interface is used to retrieve runtime status information
** about the preformance of SQLite, and optionally to reset various
** highwater marks.  ^The first argument is an integer code for
** the specific parameter to measure.  ^(Recognized integer codes
** are of the form [SQLITE_STATUS_MEMORY_USED | SQLITE_STATUS_...].)^
** ^The current value of the parameter is returned into *pCurrent.
** ^The highest recorded value is returned in *pHighwater.  ^If the
** resetFlag is true, then the highest record value is reset after
** *pHighwater is written.  ^(Some parameters do not record the highest
** value.  For those parameters
** nothing is written into *pHighwater and the resetFlag is ignored.)^
** ^(Other parameters record only the highwater mark and not the current
** value.  For these latter parameters nothing is written into *pCurrent.)^
**
** ^The sqlite3_db_status() routine returns SQLITE_OK on success and a
** non-zero [error code] on failure.
**
** This routine is threadsafe but is not atomic.  This routine can be
** called while other threads are running the same or different SQLite
** interfaces.  However the values returned in *pCurrent and
** *pHighwater reflect the status of SQLite at different points in time
** and it is possible that another thread might change the parameter
** in between the times when *pCurrent and *pHighwater are written.
**
** See also: [sqlite3_db_status()]
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);


/*
** CAPI3REF: Status Parameters
** EXPERIMENTAL
**
** These integer constants designate various run-time status parameters
** that can be returned by [sqlite3_status()].
**
** <dl>
** ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>
** <dd>This parameter is the current amount of memory checked out
** using [sqlite3_malloc()], either directly or indirectly.  The
** figure includes calls made to [sqlite3_malloc()] by the application
** and internal memory usage by the SQLite library.  Scratch memory
** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache
** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
** this parameter.  The amount returned is the sum of the allocation
** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^
**
** ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt>
** <dd>This parameter records the largest memory allocation request
** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
** internal equivalents).  Only the value returned in the
** *pHighwater parameter to [sqlite3_status()] is of interest.
** The value written into the *pCurrent parameter is undefined.</dd>)^
**
** ^(<dt>SQLITE_STATUS_PAGECACHE_USED</dt>
** <dd>This parameter returns the number of pages used out of the
** [pagecache memory allocator] that was configured using
** [SQLITE_CONFIG_PAGECACHE].  The
** value returned is in pages, not in bytes.</dd>)^
**
** ^(<dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt>
** <dd>This parameter returns the number of bytes of page cache
** allocation which could not be statisfied by the [SQLITE_CONFIG_PAGECACHE]
** buffer and where forced to overflow to [sqlite3_malloc()].  The
** returned value includes allocations that overflowed because they
** where too large (they were larger than the "sz" parameter to
** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because
** no space was left in the page cache.</dd>)^
**
** ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>
** <dd>This parameter records the largest memory allocation request
** handed to [pagecache memory allocator].  Only the value returned in the
** *pHighwater parameter to [sqlite3_status()] is of interest.
** The value written into the *pCurrent parameter is undefined.</dd>)^
**
** ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt>
** <dd>This parameter returns the number of allocations used out of the
** [scratch memory allocator] configured using
** [SQLITE_CONFIG_SCRATCH].  The value returned is in allocations, not
** in bytes.  Since a single thread may only have one scratch allocation
** outstanding at time, this parameter also reports the number of threads
** using scratch memory at the same time.</dd>)^
**
** ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>
** <dd>This parameter returns the number of bytes of scratch memory
** allocation which could not be statisfied by the [SQLITE_CONFIG_SCRATCH]
** buffer and where forced to overflow to [sqlite3_malloc()].  The values
** returned include overflows because the requested allocation was too
** larger (that is, because the requested allocation was larger than the
** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer
** slots were available.
** </dd>)^
**
** ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
** <dd>This parameter records the largest memory allocation request
** handed to [scratch memory allocator].  Only the value returned in the
** *pHighwater parameter to [sqlite3_status()] is of interest.
** The value written into the *pCurrent parameter is undefined.</dd>)^
**
** ^(<dt>SQLITE_STATUS_PARSER_STACK</dt>
** <dd>This parameter records the deepest parser stack.  It is only
** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^
** </dl>
**
** New status parameters may be added from time to time.
*/
#define SQLITE_STATUS_MEMORY_USED          0
#define SQLITE_STATUS_PAGECACHE_USED       1
#define SQLITE_STATUS_PAGECACHE_OVERFLOW   2
#define SQLITE_STATUS_SCRATCH_USED         3
#define SQLITE_STATUS_SCRATCH_OVERFLOW     4
#define SQLITE_STATUS_MALLOC_SIZE          5
#define SQLITE_STATUS_PARSER_STACK         6
#define SQLITE_STATUS_PAGECACHE_SIZE       7
#define SQLITE_STATUS_SCRATCH_SIZE         8

/*
** CAPI3REF: Database Connection Status
** EXPERIMENTAL
**
** ^This interface is used to retrieve runtime status information
** about a single [database connection].  ^The first argument is the
** database connection object to be interrogated.  ^The second argument
** is the parameter to interrogate.  ^Currently, the only allowed value
** for the second parameter is [SQLITE_DBSTATUS_LOOKASIDE_USED].
** Additional options will likely appear in future releases of SQLite.
**
** ^The current value of the requested parameter is written into *pCur
** and the highest instantaneous value is written into *pHiwtr.  ^If
** the resetFlg is true, then the highest instantaneous value is
** reset back down to the current value.
**
** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);

/*
** CAPI3REF: Status Parameters for database connections
** EXPERIMENTAL
**
** These constants are the available integer "verbs" that can be passed as
** the second argument to the [sqlite3_db_status()] interface.
**
** New verbs may be added in future releases of SQLite. Existing verbs
** might be discontinued. Applications should check the return code from
** [sqlite3_db_status()] to make sure that the call worked.
** The [sqlite3_db_status()] interface will return a non-zero error code
** if a discontinued or unsupported verb is invoked.
**
** <dl>
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
** <dd>This parameter returns the number of lookaside memory slots currently
** checked out.</dd>)^
** </dl>
*/
#define SQLITE_DBSTATUS_LOOKASIDE_USED     0


/*
** CAPI3REF: Prepared Statement Status
** EXPERIMENTAL
**
** ^(Each prepared statement maintains various
** [SQLITE_STMTSTATUS_SORT | counters] that measure the number
** of times it has performed specific operations.)^  These counters can
** be used to monitor the performance characteristics of the prepared
** statements.  For example, if the number of table steps greatly exceeds
** the number of table searches or result rows, that would tend to indicate
** that the prepared statement is using a full table scan rather than
** an index.
**
** ^(This interface is used to retrieve and reset counter values from
** a [prepared statement].  The first argument is the prepared statement
** object to be interrogated.  The second argument
** is an integer code for a specific [SQLITE_STMTSTATUS_SORT | counter]
** to be interrogated.)^
** ^The current value of the requested counter is returned.
** ^If the resetFlg is true, then the counter is reset to zero after this
** interface call returns.
**
** See also: [sqlite3_status()] and [sqlite3_db_status()].
*/
SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);

/*
** CAPI3REF: Status Parameters for prepared statements
** EXPERIMENTAL
**
** These preprocessor macros define integer codes that name counter
** values associated with the [sqlite3_stmt_status()] interface.
** The meanings of the various counters are as follows:
**
** <dl>
** <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>
** <dd>^This is the number of times that SQLite has stepped forward in
** a table as part of a full table scan.  Large numbers for this counter
** may indicate opportunities for performance improvement through
** careful use of indices.</dd>
**
** <dt>SQLITE_STMTSTATUS_SORT</dt>
** <dd>^This is the number of sort operations that have occurred.
** A non-zero value in this counter may indicate an opportunity to
** improvement performance through careful use of indices.</dd>
**
** </dl>
*/
#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
#define SQLITE_STMTSTATUS_SORT              2

/*
** CAPI3REF: Custom Page Cache Object
** EXPERIMENTAL
**
** The sqlite3_pcache type is opaque.  It is implemented by
** the pluggable module.  The SQLite core has no knowledge of
** its size or internal structure and never deals with the
** sqlite3_pcache object except by holding and passing pointers
** to the object.
**
** See [sqlite3_pcache_methods] for additional information.
*/
typedef struct sqlite3_pcache sqlite3_pcache;

/*
** CAPI3REF: Application Defined Page Cache.
** KEYWORDS: {page cache}
** EXPERIMENTAL
**
** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE], ...) interface can
** register an alternative page cache implementation by passing in an
** instance of the sqlite3_pcache_methods structure.)^ The majority of the
** heap memory used by SQLite is used by the page cache to cache data read
** from, or ready to be written to, the database file. By implementing a
** custom page cache using this API, an application can control more
** precisely the amount of memory consumed by SQLite, the way in which
** that memory is allocated and released, and the policies used to
** determine exactly which parts of a database file are cached and for
** how long.
**
** ^(The contents of the sqlite3_pcache_methods structure are copied to an
** internal buffer by SQLite within the call to [sqlite3_config].  Hence
** the application may discard the parameter after the call to
** [sqlite3_config()] returns.)^
**
** ^The xInit() method is called once for each call to [sqlite3_initialize()]
** (usually only once during the lifetime of the process). ^(The xInit()
** method is passed a copy of the sqlite3_pcache_methods.pArg value.)^
** ^The xInit() method can set up up global structures and/or any mutexes
** required by the custom page cache implementation.
**
** ^The xShutdown() method is called from within [sqlite3_shutdown()],
** if the application invokes this API. It can be used to clean up
** any outstanding resources before process shutdown, if required.
**
** ^SQLite holds a [SQLITE_MUTEX_RECURSIVE] mutex when it invokes
** the xInit method, so the xInit method need not be threadsafe.  ^The
** xShutdown method is only called from [sqlite3_shutdown()] so it does
** not need to be threadsafe either.  All other methods must be threadsafe
** in multithreaded applications.
**
** ^SQLite will never invoke xInit() more than once without an intervening
** call to xShutdown().
**
** ^The xCreate() method is used to construct a new cache instance.  SQLite
** will typically create one cache instance for each open database file,
** though this is not guaranteed. ^The
** first parameter, szPage, is the size in bytes of the pages that must
** be allocated by the cache.  ^szPage will not be a power of two.  ^szPage
** will the page size of the database file that is to be cached plus an
** increment (here called "R") of about 100 or 200.  ^SQLite will use the
** extra R bytes on each page to store metadata about the underlying
** database page on disk.  The value of R depends
** on the SQLite version, the target platform, and how SQLite was compiled.
** ^R is constant for a particular build of SQLite.  ^The second argument to
** xCreate(), bPurgeable, is true if the cache being created will
** be used to cache database pages of a file stored on disk, or
** false if it is used for an in-memory database. ^The cache implementation
** does not have to do anything special based with the value of bPurgeable;
** it is purely advisory.  ^On a cache where bPurgeable is false, SQLite will
** never invoke xUnpin() except to deliberately delete a page.
** ^In other words, a cache created with bPurgeable set to false will
** never contain any unpinned pages.
**
** ^(The xCachesize() method may be called at any time by SQLite to set the
** suggested maximum cache-size (number of pages stored by) the cache
** instance passed as the first argument. This is the value configured using
** the SQLite "[PRAGMA cache_size]" command.)^  ^As with the bPurgeable
** parameter, the implementation is not required to do anything with this
** value; it is advisory only.
**
** ^The xPagecount() method should return the number of pages currently
** stored in the cache.
**
** ^The xFetch() method is used to fetch a page and return a pointer to it.
** ^A 'page', in this context, is a buffer of szPage bytes aligned at an
** 8-byte boundary. ^The page to be fetched is determined by the key. ^The
** mimimum key value is 1. After it has been retrieved using xFetch, the page
** is considered to be "pinned".
**
** ^If the requested page is already in the page cache, then the page cache
** implementation must return a pointer to the page buffer with its content
** intact.  ^(If the requested page is not already in the cache, then the
** behavior of the cache implementation is determined by the value of the
** createFlag parameter passed to xFetch, according to the following table:
**
** <table border=1 width=85% align=center>
** <tr><th> createFlag <th> Behaviour when page is not already in cache
** <tr><td> 0 <td> Do not allocate a new page.  Return NULL.
** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
**                 Otherwise return NULL.
** <tr><td> 2 <td> Make every effort to allocate a new page.  Only return
**                 NULL if allocating a new page is effectively impossible.
** </table>)^
**
** SQLite will normally invoke xFetch() with a createFlag of 0 or 1.  If
** a call to xFetch() with createFlag==1 returns NULL, then SQLite will
** attempt to unpin one or more cache pages by spilling the content of
** pinned pages to disk and synching the operating system disk cache. After
** attempting to unpin pages, the xFetch() method will be invoked again with
** a createFlag of 2.
**
** ^xUnpin() is called by SQLite with a pointer to a currently pinned page
** as its second argument. ^(If the third parameter, discard, is non-zero,
** then the page should be evicted from the cache. In this case SQLite
** assumes that the next time the page is retrieved from the cache using
** the xFetch() method, it will be zeroed.)^ ^If the discard parameter is
** zero, then the page is considered to be unpinned. ^The cache implementation
** may choose to evict unpinned pages at any time.
**
** ^(The cache is not required to perform any reference counting. A single
** call to xUnpin() unpins the page regardless of the number of prior calls
** to xFetch().)^
**
** ^The xRekey() method is used to change the key value associated with the
** page passed as the second argument from oldKey to newKey. ^If the cache
** previously contains an entry associated with newKey, it should be
** discarded. ^Any prior cache entry associated with newKey is guaranteed not
** to be pinned.
**
** ^When SQLite calls the xTruncate() method, the cache must discard all
** existing cache entries with page numbers (keys) greater than or equal
** to the value of the iLimit parameter passed to xTruncate(). ^If any
** of these pages are pinned, they are implicitly unpinned, meaning that
** they can be safely discarded.
**
** ^The xDestroy() method is used to delete a cache allocated by xCreate().
** All resources associated with the specified cache should be freed. ^After
** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
** handle invalid, and will not use it with any other sqlite3_pcache_methods
** functions.
*/
typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
struct sqlite3_pcache_methods {
  void *pArg;
  int (*xInit)(void*);
  void (*xShutdown)(void*);
  sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
  void (*xCachesize)(sqlite3_pcache*, int nCachesize);
  int (*xPagecount)(sqlite3_pcache*);
  void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
  void (*xUnpin)(sqlite3_pcache*, void*, int discard);
  void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
  void (*xDestroy)(sqlite3_pcache*);
};

/*
** CAPI3REF: Online Backup Object
** EXPERIMENTAL
**
** The sqlite3_backup object records state information about an ongoing
** online backup operation.  ^The sqlite3_backup object is created by
** a call to [sqlite3_backup_init()] and is destroyed by a call to
** [sqlite3_backup_finish()].
**
** See Also: [Using the SQLite Online Backup API]
*/
typedef struct sqlite3_backup sqlite3_backup;

/*
** CAPI3REF: Online Backup API.
** EXPERIMENTAL
**
** The backup API copies the content of one database into another.
** It is useful either for creating backups of databases or
** for copying in-memory databases to or from persistent files.
**
** See Also: [Using the SQLite Online Backup API]
**
** ^Exclusive access is required to the destination database for the
** duration of the operation. ^However the source database is only
** read-locked while it is actually being read; it is not locked
** continuously for the entire backup operation. ^Thus, the backup may be
** performed on a live source database without preventing other users from
** reading or writing to the source database while the backup is underway.
**
** ^(To perform a backup operation:
**   <ol>
**     <li><b>sqlite3_backup_init()</b> is called once to initialize the
**         backup,
**     <li><b>sqlite3_backup_step()</b> is called one or more times to transfer
**         the data between the two databases, and finally
**     <li><b>sqlite3_backup_finish()</b> is called to release all resources
**         associated with the backup operation.
**   </ol>)^
** There should be exactly one call to sqlite3_backup_finish() for each
** successful call to sqlite3_backup_init().
**
** <b>sqlite3_backup_init()</b>
**
** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the
** [database connection] associated with the destination database
** and the database name, respectively.
** ^The database name is "main" for the main database, "temp" for the
** temporary database, or the name specified after the AS keyword in
** an [ATTACH] statement for an attached database.
** ^The S and M arguments passed to
** sqlite3_backup_init(D,N,S,M) identify the [database connection]
** and database name of the source database, respectively.
** ^The source and destination [database connections] (parameters S and D)
** must be different or else sqlite3_backup_init(D,N,S,M) will file with
** an error.
**
** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is
** returned and an error code and error message are store3d in the
** destination [database connection] D.
** ^The error code and message for the failed call to sqlite3_backup_init()
** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or
** [sqlite3_errmsg16()] functions.
** ^A successful call to sqlite3_backup_init() returns a pointer to an
** [sqlite3_backup] object.
** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and
** sqlite3_backup_finish() functions to perform the specified backup
** operation.
**
** <b>sqlite3_backup_step()</b>
**
** ^Function sqlite3_backup_step(B,N) will copy up to N pages between
** the source and destination databases specified by [sqlite3_backup] object B.
** ^If N is negative, all remaining source pages are copied.
** ^If sqlite3_backup_step(B,N) successfully copies N pages and there
** are still more pages to be copied, then the function resturns [SQLITE_OK].
** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages
** from source to destination, then it returns [SQLITE_DONE].
** ^If an error occurs while running sqlite3_backup_step(B,N),
** then an [error code] is returned. ^As well as [SQLITE_OK] and
** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],
** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an
** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code.
**
** ^The sqlite3_backup_step() might return [SQLITE_READONLY] if the destination
** database was opened read-only or if
** the destination is an in-memory database with a different page size
** from the source database.
**
** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then
** the [sqlite3_busy_handler | busy-handler function]
** is invoked (if one is specified). ^If the
** busy-handler returns non-zero before the lock is available, then
** [SQLITE_BUSY] is returned to the caller. ^In this case the call to
** sqlite3_backup_step() can be retried later. ^If the source
** [database connection]
** is being used to write to the source database when sqlite3_backup_step()
** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this
** case the call to sqlite3_backup_step() can be retried later on. ^(If
** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX], [SQLITE_NOMEM], or
** [SQLITE_READONLY] is returned, then
** there is no point in retrying the call to sqlite3_backup_step(). These
** errors are considered fatal.)^  The application must accept
** that the backup operation has failed and pass the backup operation handle
** to the sqlite3_backup_finish() to release associated resources.
**
** ^The first call to sqlite3_backup_step() obtains an exclusive lock
** on the destination file. ^The exclusive lock is not released until either
** sqlite3_backup_finish() is called or the backup operation is complete
** and sqlite3_backup_step() returns [SQLITE_DONE].  ^Every call to
** sqlite3_backup_step() obtains a [shared lock] on the source database that
** lasts for the duration of the sqlite3_backup_step() call.
** ^Because the source database is not locked between calls to
** sqlite3_backup_step(), the source database may be modified mid-way
** through the backup process.  ^If the source database is modified by an
** external process or via a database connection other than the one being
** used by the backup operation, then the backup will be automatically
** restarted by the next call to sqlite3_backup_step(). ^If the source
** database is modified by the using the same database connection as is used
** by the backup operation, then the backup database is automatically
** updated at the same time.
**
** <b>sqlite3_backup_finish()</b>
**
** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the
** application wishes to abandon the backup operation, the application
** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish().
** ^The sqlite3_backup_finish() interfaces releases all
** resources associated with the [sqlite3_backup] object.
** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any
** active write-transaction on the destination database is rolled back.
** The [sqlite3_backup] object is invalid
** and may not be used following a call to sqlite3_backup_finish().
**
** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no
** sqlite3_backup_step() errors occurred, regardless or whether or not
** sqlite3_backup_step() completed.
** ^If an out-of-memory condition or IO error occurred during any prior
** sqlite3_backup_step() call on the same [sqlite3_backup] object, then
** sqlite3_backup_finish() returns the corresponding [error code].
**
** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step()
** is not a permanent error and does not affect the return value of
** sqlite3_backup_finish().
**
** <b>sqlite3_backup_remaining(), sqlite3_backup_pagecount()</b>
**
** ^Each call to sqlite3_backup_step() sets two values inside
** the [sqlite3_backup] object: the number of pages still to be backed
** up and the total number of pages in the source databae file.
** The sqlite3_backup_remaining() and sqlite3_backup_pagecount() interfaces
** retrieve these two values, respectively.
**
** ^The values returned by these functions are only updated by
** sqlite3_backup_step(). ^If the source database is modified during a backup
** operation, then the values are not updated to account for any extra
** pages that need to be updated or the size of the source database file
** changing.
**
** <b>Concurrent Usage of Database Handles</b>
**
** ^The source [database connection] may be used by the application for other
** purposes while a backup operation is underway or being initialized.
** ^If SQLite is compiled and configured to support threadsafe database
** connections, then the source database connection may be used concurrently
** from within other threads.
**
** However, the application must guarantee that the destination
** [database connection] is not passed to any other API (by any thread) after
** sqlite3_backup_init() is called and before the corresponding call to
** sqlite3_backup_finish().  SQLite does not currently check to see
** if the application incorrectly accesses the destination [database connection]
** and so no error code is reported, but the operations may malfunction
** nevertheless.  Use of the destination database connection while a
** backup is in progress might also also cause a mutex deadlock.
**
** If running in [shared cache mode], the application must
** guarantee that the shared cache used by the destination database
** is not accessed while the backup is running. In practice this means
** that the application must guarantee that the disk file being
** backed up to is not accessed by any connection within the process,
** not just the specific connection that was passed to sqlite3_backup_init().
**
** The [sqlite3_backup] object itself is partially threadsafe. Multiple
** threads may safely make multiple concurrent calls to sqlite3_backup_step().
** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()
** APIs are not strictly speaking threadsafe. If they are invoked at the
** same time as another thread is invoking sqlite3_backup_step() it is
** possible that they return invalid values.
*/
SQLITE_API sqlite3_backup *sqlite3_backup_init(
  sqlite3 *pDest,                        /* Destination database handle */
  const char *zDestName,                 /* Destination database name */
  sqlite3 *pSource,                      /* Source database handle */
  const char *zSourceName                /* Source database name */
);
SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage);
SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p);
SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p);
SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p);

/*
** CAPI3REF: Unlock Notification
** EXPERIMENTAL
**
** ^When running in shared-cache mode, a database operation may fail with
** an [SQLITE_LOCKED] error if the required locks on the shared-cache or
** individual tables within the shared-cache cannot be obtained. See
** [SQLite Shared-Cache Mode] for a description of shared-cache locking.
** ^This API may be used to register a callback that SQLite will invoke
** when the connection currently holding the required lock relinquishes it.
** ^This API is only available if the library was compiled with the
** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined.
**
** See Also: [Using the SQLite Unlock Notification Feature].
**
** ^Shared-cache locks are released when a database connection concludes
** its current transaction, either by committing it or rolling it back.
**
** ^When a connection (known as the blocked connection) fails to obtain a
** shared-cache lock and SQLITE_LOCKED is returned to the caller, the
** identity of the database connection (the blocking connection) that
** has locked the required resource is stored internally. ^After an
** application receives an SQLITE_LOCKED error, it may call the
** sqlite3_unlock_notify() method with the blocked connection handle as
** the first argument to register for a callback that will be invoked
** when the blocking connections current transaction is concluded. ^The
** callback is invoked from within the [sqlite3_step] or [sqlite3_close]
** call that concludes the blocking connections transaction.
**
** ^(If sqlite3_unlock_notify() is called in a multi-threaded application,
** there is a chance that the blocking connection will have already
** concluded its transaction by the time sqlite3_unlock_notify() is invoked.
** If this happens, then the specified callback is invoked immediately,
** from within the call to sqlite3_unlock_notify().)^
**
** ^If the blocked connection is attempting to obtain a write-lock on a
** shared-cache table, and more than one other connection currently holds
** a read-lock on the same table, then SQLite arbitrarily selects one of
** the other connections to use as the blocking connection.
**
** ^(There may be at most one unlock-notify callback registered by a
** blocked connection. If sqlite3_unlock_notify() is called when the
** blocked connection already has a registered unlock-notify callback,
** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is
** called with a NULL pointer as its second argument, then any existing
** unlock-notify callback is cancelled. ^The blocked connections
** unlock-notify callback may also be canceled by closing the blocked
** connection using [sqlite3_close()].
**
** The unlock-notify callback is not reentrant. If an application invokes
** any sqlite3_xxx API functions from within an unlock-notify callback, a
** crash or deadlock may be the result.
**
** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always
** returns SQLITE_OK.
**
** <b>Callback Invocation Details</b>
**
** When an unlock-notify callback is registered, the application provides a
** single void* pointer that is passed to the callback when it is invoked.
** However, the signature of the callback function allows SQLite to pass
** it an array of void* context pointers. The first argument passed to
** an unlock-notify callback is a pointer to an array of void* pointers,
** and the second is the number of entries in the array.
**
** When a blocking connections transaction is concluded, there may be
** more than one blocked connection that has registered for an unlock-notify
** callback. ^If two or more such blocked connections have specified the
** same callback function, then instead of invoking the callback function
** multiple times, it is invoked once with the set of void* context pointers
** specified by the blocked connections bundled together into an array.
** This gives the application an opportunity to prioritize any actions
** related to the set of unblocked database connections.
**
** <b>Deadlock Detection</b>
**
** Assuming that after registering for an unlock-notify callback a
** database waits for the callback to be issued before taking any further
** action (a reasonable assumption), then using this API may cause the
** application to deadlock. For example, if connection X is waiting for
** connection Y's transaction to be concluded, and similarly connection
** Y is waiting on connection X's transaction, then neither connection
** will proceed and the system may remain deadlocked indefinitely.
**
** To avoid this scenario, the sqlite3_unlock_notify() performs deadlock
** detection. ^If a given call to sqlite3_unlock_notify() would put the
** system in a deadlocked state, then SQLITE_LOCKED is returned and no
** unlock-notify callback is registered. The system is said to be in
** a deadlocked state if connection A has registered for an unlock-notify
** callback on the conclusion of connection B's transaction, and connection
** B has itself registered for an unlock-notify callback when connection
** A's transaction is concluded. ^Indirect deadlock is also detected, so
** the system is also considered to be deadlocked if connection B has
** registered for an unlock-notify callback on the conclusion of connection
** C's transaction, where connection C is waiting on connection A. ^Any
** number of levels of indirection are allowed.
**
** <b>The "DROP TABLE" Exception</b>
**
** When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost
** always appropriate to call sqlite3_unlock_notify(). There is however,
** one exception. When executing a "DROP TABLE" or "DROP INDEX" statement,
** SQLite checks if there are any currently executing SELECT statements
** that belong to the same connection. If there are, SQLITE_LOCKED is
** returned. In this case there is no "blocking connection", so invoking
** sqlite3_unlock_notify() results in the unlock-notify callback being
** invoked immediately. If the application then re-attempts the "DROP TABLE"
** or "DROP INDEX" query, an infinite loop might be the result.
**
** One way around this problem is to check the extended error code returned
** by an sqlite3_step() call. ^(If there is a blocking connection, then the
** extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in
** the special "DROP TABLE/INDEX" case, the extended error code is just
** SQLITE_LOCKED.)^
*/
SQLITE_API int sqlite3_unlock_notify(
  sqlite3 *pBlocked,                          /* Waiting connection */
  void (*xNotify)(void **apArg, int nArg),    /* Callback function to invoke */
  void *pNotifyArg                            /* Argument to pass to xNotify */
);


/*
** CAPI3REF: String Comparison
** EXPERIMENTAL
**
** ^The [sqlite3_strnicmp()] API allows applications and extensions to
** compare the contents of two buffers containing UTF-8 strings in a
** case-indendent fashion, using the same definition of case independence
** that SQLite uses internally when comparing identifiers.
*/
SQLITE_API int sqlite3_strnicmp(const char *, const char *, int);

/*
** CAPI3REF: Error Logging Interface
** EXPERIMENTAL
**
** ^The [sqlite3_log()] interface writes a message into the error log
** established by the [SQLITE_CONFIG_ERRORLOG] option to [sqlite3_config()].
**
** The sqlite3_log() interface is intended for use by extensions such as
** virtual tables, collating functions, and SQL functions.  While there is
** nothing to prevent an application from calling sqlite3_log(), doing so
** is considered bad form.
**
** To avoid deadlocks and other threading problems, the sqlite3_log() routine
** will not use dynamically allocated memory.  The log message is stored in
** a fixed-length buffer on the stack.  If the log message is longer than
** a few hundred characters, it will be truncated to the length of the
** buffer.
*/
SQLITE_API void sqlite3_log(int iErrCode, const char *zFormat, ...);

/*
** Undo the hack that converts floating point types to integer for
** builds on processors without floating point support.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double
#endif

#if 0
}  /* End of the 'extern "C"' block */
#endif
#endif


/************** End of sqlite3.h *********************************************/
// Begin Android Add
#define SQLITE_BeginImmediate 0x00200000  /* Default BEGIN to IMMEDIATE */
#define fdatasync fsync
#undef __APPLE__
// End Android Add
/************** Continuing where we left off in sqliteInt.h ******************/
/************** Include hash.h in the middle of sqliteInt.h ******************/
/************** Begin file hash.h ********************************************/
/*
** 2001 September 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the header file for the generic hash-table implemenation
** used in SQLite.
*/
#ifndef _SQLITE_HASH_H_
#define _SQLITE_HASH_H_

/* Forward declarations of structures. */
typedef struct Hash Hash;
typedef struct HashElem HashElem;

/* A complete hash table is an instance of the following structure.
** The internals of this structure are intended to be opaque -- client
** code should not attempt to access or modify the fields of this structure
** directly.  Change this structure only by using the routines below.
** However, some of the "procedures" and "functions" for modifying and
** accessing this structure are really macros, so we can't really make
** this structure opaque.
**
** All elements of the hash table are on a single doubly-linked list.
** Hash.first points to the head of this list.
**
** There are Hash.htsize buckets.  Each bucket points to a spot in
** the global doubly-linked list.  The contents of the bucket are the
** element pointed to plus the next _ht.count-1 elements in the list.
**
** Hash.htsize and Hash.ht may be zero.  In that case lookup is done
** by a linear search of the global list.  For small tables, the
** Hash.ht table is never allocated because if there are few elements
** in the table, it is faster to do a linear search than to manage
** the hash table.
*/
struct Hash {
  unsigned int htsize;      /* Number of buckets in the hash table */
  unsigned int count;       /* Number of entries in this table */
  HashElem *first;          /* The first element of the array */
  struct _ht {              /* the hash table */
    int count;                 /* Number of entries with this hash */
    HashElem *chain;           /* Pointer to first entry with this hash */
  } *ht;
};

/* Each element in the hash table is an instance of the following
** structure.  All elements are stored on a single doubly-linked list.
**
** Again, this structure is intended to be opaque, but it can't really
** be opaque because it is used by macros.
*/
struct HashElem {
  HashElem *next, *prev;       /* Next and previous elements in the table */
  void *data;                  /* Data associated with this element */
  const char *pKey; int nKey;  /* Key associated with this element */
};

/*
** Access routines.  To delete, insert a NULL pointer.
*/
SQLITE_PRIVATE void sqlite3HashInit(Hash*);
SQLITE_PRIVATE void *sqlite3HashInsert(Hash*, const char *pKey, int nKey, void *pData);
SQLITE_PRIVATE void *sqlite3HashFind(const Hash*, const char *pKey, int nKey);
SQLITE_PRIVATE void sqlite3HashClear(Hash*);

/*
** Macros for looping over all elements of a hash table.  The idiom is
** like this:
**
**   Hash h;
**   HashElem *p;
**   ...
**   for(p=sqliteHashFirst(&h); p; p=sqliteHashNext(p)){
**     SomeStructure *pData = sqliteHashData(p);
**     // do something with pData
**   }
*/
#define sqliteHashFirst(H)  ((H)->first)
#define sqliteHashNext(E)   ((E)->next)
#define sqliteHashData(E)   ((E)->data)
/* #define sqliteHashKey(E)    ((E)->pKey) // NOT USED */
/* #define sqliteHashKeysize(E) ((E)->nKey)  // NOT USED */

/*
** Number of entries in a hash table
*/
/* #define sqliteHashCount(H)  ((H)->count) // NOT USED */

#endif /* _SQLITE_HASH_H_ */

/************** End of hash.h ************************************************/
/************** Continuing where we left off in sqliteInt.h ******************/
/************** Include parse.h in the middle of sqliteInt.h *****************/
/************** Begin file parse.h *******************************************/
#define TK_SEMI                            1
#define TK_EXPLAIN                         2
#define TK_QUERY                           3
#define TK_PLAN                            4
#define TK_BEGIN                           5
#define TK_TRANSACTION                     6
#define TK_DEFERRED                        7
#define TK_IMMEDIATE                       8
#define TK_EXCLUSIVE                       9
#define TK_COMMIT                         10
#define TK_END                            11
#define TK_ROLLBACK                       12
#define TK_SAVEPOINT                      13
#define TK_RELEASE                        14
#define TK_TO                             15
#define TK_TABLE                          16
#define TK_CREATE                         17
#define TK_IF                             18
#define TK_NOT                            19
#define TK_EXISTS                         20
#define TK_TEMP                           21
#define TK_LP                             22
#define TK_RP                             23
#define TK_AS                             24
#define TK_COMMA                          25
#define TK_ID                             26
#define TK_INDEXED                        27
#define TK_ABORT                          28
#define TK_ACTION                         29
#define TK_AFTER                          30
#define TK_ANALYZE                        31
#define TK_ASC                            32
#define TK_ATTACH                         33
#define TK_BEFORE                         34
#define TK_BY                             35
#define TK_CASCADE                        36
#define TK_CAST                           37
#define TK_COLUMNKW                       38
#define TK_CONFLICT                       39
#define TK_DATABASE                       40
#define TK_DESC                           41
#define TK_DETACH                         42
#define TK_EACH                           43
#define TK_FAIL                           44
#define TK_FOR                            45
#define TK_IGNORE                         46
#define TK_INITIALLY                      47
#define TK_INSTEAD                        48
#define TK_LIKE_KW                        49
#define TK_MATCH                          50
#define TK_NO                             51
#define TK_KEY                            52
#define TK_OF                             53
#define TK_OFFSET                         54
#define TK_PRAGMA                         55
#define TK_RAISE                          56
#define TK_REPLACE                        57
#define TK_RESTRICT                       58
#define TK_ROW                            59
#define TK_TRIGGER                        60
#define TK_VACUUM                         61
#define TK_VIEW                           62
#define TK_VIRTUAL                        63
#define TK_REINDEX                        64
#define TK_RENAME                         65
#define TK_CTIME_KW                       66
#define TK_ANY                            67
#define TK_OR                             68
#define TK_AND                            69
#define TK_IS                             70
#define TK_BETWEEN                        71
#define TK_IN                             72
#define TK_ISNULL                         73
#define TK_NOTNULL                        74
#define TK_NE                             75
#define TK_EQ                             76
#define TK_GT                             77
#define TK_LE                             78
#define TK_LT                             79
#define TK_GE                             80
#define TK_ESCAPE                         81
#define TK_BITAND                         82
#define TK_BITOR                          83
#define TK_LSHIFT                         84
#define TK_RSHIFT                         85
#define TK_PLUS                           86
#define TK_MINUS                          87
#define TK_STAR                           88
#define TK_SLASH                          89
#define TK_REM                            90
#define TK_CONCAT                         91
#define TK_COLLATE                        92
#define TK_BITNOT                         93
#define TK_STRING                         94
#define TK_JOIN_KW                        95
#define TK_CONSTRAINT                     96
#define TK_DEFAULT                        97
#define TK_NULL                           98
#define TK_PRIMARY                        99
#define TK_UNIQUE                         100
#define TK_CHECK                          101
#define TK_REFERENCES                     102
#define TK_AUTOINCR                       103
#define TK_ON                             104
#define TK_INSERT                         105
#define TK_DELETE                         106
#define TK_UPDATE                         107
#define TK_SET                            108
#define TK_DEFERRABLE                     109
#define TK_FOREIGN                        110
#define TK_DROP                           111
#define TK_UNION                          112
#define TK_ALL                            113
#define TK_EXCEPT                         114
#define TK_INTERSECT                      115
#define TK_SELECT                         116
#define TK_DISTINCT                       117
#define TK_DOT                            118
#define TK_FROM                           119
#define TK_JOIN                           120
#define TK_USING                          121
#define TK_ORDER                          122
#define TK_GROUP                          123
#define TK_HAVING                         124
#define TK_LIMIT                          125
#define TK_WHERE                          126
#define TK_INTO                           127
#define TK_VALUES                         128
#define TK_INTEGER                        129
#define TK_FLOAT                          130
#define TK_BLOB                           131
#define TK_REGISTER                       132
#define TK_VARIABLE                       133
#define TK_CASE                           134
#define TK_WHEN                           135
#define TK_THEN                           136
#define TK_ELSE                           137
#define TK_INDEX                          138
#define TK_ALTER                          139
#define TK_ADD                            140
#define TK_TO_TEXT                        141
#define TK_TO_BLOB                        142
#define TK_TO_NUMERIC                     143
#define TK_TO_INT                         144
#define TK_TO_REAL                        145
#define TK_ISNOT                          146
#define TK_END_OF_FILE                    147
#define TK_ILLEGAL                        148
#define TK_SPACE                          149
#define TK_UNCLOSED_STRING                150
#define TK_FUNCTION                       151
#define TK_COLUMN                         152
#define TK_AGG_FUNCTION                   153
#define TK_AGG_COLUMN                     154
#define TK_CONST_FUNC                     155
#define TK_UMINUS                         156
#define TK_UPLUS                          157

/************** End of parse.h ***********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stddef.h>

/*
** If compiling for a processor that lacks floating point support,
** substitute integer for floating-point
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# define double sqlite_int64
# define LONGDOUBLE_TYPE sqlite_int64
# ifndef SQLITE_BIG_DBL
#   define SQLITE_BIG_DBL (((sqlite3_int64)1)<<50)
# endif
# define SQLITE_OMIT_DATETIME_FUNCS 1
# define SQLITE_OMIT_TRACE 1
# undef SQLITE_MIXED_ENDIAN_64BIT_FLOAT
# undef SQLITE_HAVE_ISNAN
#endif
#ifndef SQLITE_BIG_DBL
# define SQLITE_BIG_DBL (1e99)
#endif

/*
** OMIT_TEMPDB is set to 1 if SQLITE_OMIT_TEMPDB is defined, or 0
** afterward. Having this macro allows us to cause the C compiler
** to omit code used by TEMP tables without messy #ifndef statements.
*/
#ifdef SQLITE_OMIT_TEMPDB
#define OMIT_TEMPDB 1
#else
#define OMIT_TEMPDB 0
#endif

/*
** If the following macro is set to 1, then NULL values are considered
** distinct when determining whether or not two entries are the same
** in a UNIQUE index.  This is the way PostgreSQL, Oracle, DB2, MySQL,
** OCELOT, and Firebird all work.  The SQL92 spec explicitly says this
** is the way things are suppose to work.
**
** If the following macro is set to 0, the NULLs are indistinct for
** a UNIQUE index.  In this mode, you can only have a single NULL entry
** for a column declared UNIQUE.  This is the way Informix and SQL Server
** work.
*/
#define NULL_DISTINCT_FOR_UNIQUE 1

/*
** The "file format" number is an integer that is incremented whenever
** the VDBE-level file format changes.  The following macros define the
** the default file format for new databases and the maximum file format
** that the library can read.
*/
#define SQLITE_MAX_FILE_FORMAT 4
#ifndef SQLITE_DEFAULT_FILE_FORMAT
# define SQLITE_DEFAULT_FILE_FORMAT 1
#endif

#ifndef SQLITE_DEFAULT_RECURSIVE_TRIGGERS
# define SQLITE_DEFAULT_RECURSIVE_TRIGGERS 0
#endif

/*
** Provide a default value for SQLITE_TEMP_STORE in case it is not specified
** on the command-line
*/
#ifndef SQLITE_TEMP_STORE
# define SQLITE_TEMP_STORE 1
#endif

/*
** GCC does not define the offsetof() macro so we'll have to do it
** ourselves.
*/
#ifndef offsetof
#define offsetof(STRUCTURE,FIELD) ((int)((char*)&((STRUCTURE*)0)->FIELD))
#endif

/*
** Check to see if this machine uses EBCDIC.  (Yes, believe it or
** not, there are still machines out there that use EBCDIC.)
*/
#if 'A' == '\301'
# define SQLITE_EBCDIC 1
#else
# define SQLITE_ASCII 1
#endif

/*
** Integers of known sizes.  These typedefs might change for architectures
** where the sizes very.  Preprocessor macros are available so that the
** types can be conveniently redefined at compile-type.  Like this:
**
**         cc '-DUINTPTR_TYPE=long long int' ...
*/
#ifndef UINT32_TYPE
# ifdef HAVE_UINT32_T
#  define UINT32_TYPE uint32_t
# else
#  define UINT32_TYPE unsigned int
# endif
#endif
#ifndef UINT16_TYPE
# ifdef HAVE_UINT16_T
#  define UINT16_TYPE uint16_t
# else
#  define UINT16_TYPE unsigned short int
# endif
#endif
#ifndef INT16_TYPE
# ifdef HAVE_INT16_T
#  define INT16_TYPE int16_t
# else
#  define INT16_TYPE short int
# endif
#endif
#ifndef UINT8_TYPE
# ifdef HAVE_UINT8_T
#  define UINT8_TYPE uint8_t
# else
#  define UINT8_TYPE unsigned char
# endif
#endif
#ifndef INT8_TYPE
# ifdef HAVE_INT8_T
#  define INT8_TYPE int8_t
# else
#  define INT8_TYPE signed char
# endif
#endif
#ifndef LONGDOUBLE_TYPE
# define LONGDOUBLE_TYPE long double
#endif
typedef sqlite_int64 i64;          /* 8-byte signed integer */
typedef sqlite_uint64 u64;         /* 8-byte unsigned integer */
typedef UINT32_TYPE u32;           /* 4-byte unsigned integer */
typedef UINT16_TYPE u16;           /* 2-byte unsigned integer */
typedef INT16_TYPE i16;            /* 2-byte signed integer */
typedef UINT8_TYPE u8;             /* 1-byte unsigned integer */
typedef INT8_TYPE i8;              /* 1-byte signed integer */

/*
** SQLITE_MAX_U32 is a u64 constant that is the maximum u64 value
** that can be stored in a u32 without loss of data.  The value
** is 0x00000000ffffffff.  But because of quirks of some compilers, we
** have to specify the value in the less intuitive manner shown:
*/
#define SQLITE_MAX_U32  ((((u64)1)<<32)-1)

/*
** Macros to determine whether the machine is big or little endian,
** evaluated at runtime.
*/
#ifdef SQLITE_AMALGAMATION
SQLITE_PRIVATE const int sqlite3one = 1;
#else
SQLITE_PRIVATE const int sqlite3one;
#endif
#if defined(i386) || defined(__i386__) || defined(_M_IX86)\
                             || defined(__x86_64) || defined(__x86_64__)
# define SQLITE_BIGENDIAN    0
# define SQLITE_LITTLEENDIAN 1
# define SQLITE_UTF16NATIVE  SQLITE_UTF16LE
#else
# define SQLITE_BIGENDIAN    (*(char *)(&sqlite3one)==0)
# define SQLITE_LITTLEENDIAN (*(char *)(&sqlite3one)==1)
# define SQLITE_UTF16NATIVE (SQLITE_BIGENDIAN?SQLITE_UTF16BE:SQLITE_UTF16LE)
#endif

/*
** Constants for the largest and smallest possible 64-bit signed integers.
** These macros are designed to work correctly on both 32-bit and 64-bit
** compilers.
*/
#define LARGEST_INT64  (0xffffffff|(((i64)0x7fffffff)<<32))
#define SMALLEST_INT64 (((i64)-1) - LARGEST_INT64)

/*
** Round up a number to the next larger multiple of 8.  This is used
** to force 8-byte alignment on 64-bit architectures.
*/
#define ROUND8(x)     (((x)+7)&~7)

/*
** Round down to the nearest multiple of 8
*/
#define ROUNDDOWN8(x) ((x)&~7)

/*
** Assert that the pointer X is aligned to an 8-byte boundary.  This
** macro is used only within assert() to verify that the code gets
** all alignment restrictions correct.
**
** Except, if SQLITE_4_BYTE_ALIGNED_MALLOC is defined, then the
** underlying malloc() implemention might return us 4-byte aligned
** pointers.  In that case, only verify 4-byte alignment.
*/
#ifdef SQLITE_4_BYTE_ALIGNED_MALLOC
# define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&3)==0)
#else
# define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&7)==0)
#endif


/*
** An instance of the following structure is used to store the busy-handler
** callback for a given sqlite handle.
**
** The sqlite.busyHandler member of the sqlite struct contains the busy
** callback for the database handle. Each pager opened via the sqlite
** handle is passed a pointer to sqlite.busyHandler. The busy-handler
** callback is currently invoked only from within pager.c.
*/
typedef struct BusyHandler BusyHandler;
struct BusyHandler {
  int (*xFunc)(void *,int);  /* The busy callback */
  void *pArg;                /* First arg to busy callback */
  int nBusy;                 /* Incremented with each busy call */
};

/*
** Name of the master database table.  The master database table
** is a special table that holds the names and attributes of all
** user tables and indices.
*/
#define MASTER_NAME       "sqlite_master"
#define TEMP_MASTER_NAME  "sqlite_temp_master"

/*
** The root-page of the master database table.
*/
#define MASTER_ROOT       1

/*
** The name of the schema table.
*/
#define SCHEMA_TABLE(x)  ((!OMIT_TEMPDB)&&(x==1)?TEMP_MASTER_NAME:MASTER_NAME)

/*
** A convenience macro that returns the number of elements in
** an array.
*/
#define ArraySize(X)    ((int)(sizeof(X)/sizeof(X[0])))

/*
** The following value as a destructor means to use sqlite3DbFree().
** This is an internal extension to SQLITE_STATIC and SQLITE_TRANSIENT.
*/
#define SQLITE_DYNAMIC   ((sqlite3_destructor_type)sqlite3DbFree)

/*
** When SQLITE_OMIT_WSD is defined, it means that the target platform does
** not support Writable Static Data (WSD) such as global and static variables.
** All variables must either be on the stack or dynamically allocated from
** the heap.  When WSD is unsupported, the variable declarations scattered
** throughout the SQLite code must become constants instead.  The SQLITE_WSD
** macro is used for this purpose.  And instead of referencing the variable
** directly, we use its constant as a key to lookup the run-time allocated
** buffer that holds real variable.  The constant is also the initializer
** for the run-time allocated buffer.
**
** In the usual case where WSD is supported, the SQLITE_WSD and GLOBAL
** macros become no-ops and have zero performance impact.
*/
#ifdef SQLITE_OMIT_WSD
  #define SQLITE_WSD const
  #define GLOBAL(t,v) (*(t*)sqlite3_wsd_find((void*)&(v), sizeof(v)))
  #define sqlite3GlobalConfig GLOBAL(struct Sqlite3Config, sqlite3Config)
SQLITE_API   int sqlite3_wsd_init(int N, int J);
SQLITE_API   void *sqlite3_wsd_find(void *K, int L);
#else
  #define SQLITE_WSD
  #define GLOBAL(t,v) v
  #define sqlite3GlobalConfig sqlite3Config
#endif

/*
** The following macros are used to suppress compiler warnings and to
** make it clear to human readers when a function parameter is deliberately
** left unused within the body of a function. This usually happens when
** a function is called via a function pointer. For example the
** implementation of an SQL aggregate step callback may not use the
** parameter indicating the number of arguments passed to the aggregate,
** if it knows that this is enforced elsewhere.
**
** When a function parameter is not used at all within the body of a function,
** it is generally named "NotUsed" or "NotUsed2" to make things even clearer.
** However, these macros may also be used to suppress warnings related to
** parameters that may or may not be used depending on compilation options.
** For example those parameters only used in assert() statements. In these
** cases the parameters are named as per the usual conventions.
*/
#define UNUSED_PARAMETER(x) (void)(x)
#define UNUSED_PARAMETER2(x,y) UNUSED_PARAMETER(x),UNUSED_PARAMETER(y)

/*
** Forward references to structures
*/
typedef struct AggInfo AggInfo;
typedef struct AuthContext AuthContext;
typedef struct AutoincInfo AutoincInfo;
typedef struct Bitvec Bitvec;
typedef struct RowSet RowSet;
typedef struct CollSeq CollSeq;
typedef struct Column Column;
typedef struct Db Db;
typedef struct Schema Schema;
typedef struct Expr Expr;
typedef struct ExprList ExprList;
typedef struct ExprSpan ExprSpan;
typedef struct FKey FKey;
typedef struct FuncDef FuncDef;
typedef struct FuncDefHash FuncDefHash;
typedef struct IdList IdList;
typedef struct Index Index;
typedef struct IndexSample IndexSample;
typedef struct KeyClass KeyClass;
typedef struct KeyInfo KeyInfo;
typedef struct Lookaside Lookaside;
typedef struct LookasideSlot LookasideSlot;
typedef struct Module Module;
typedef struct NameContext NameContext;
typedef struct Parse Parse;
typedef struct Savepoint Savepoint;
typedef struct Select Select;
typedef struct SrcList SrcList;
typedef struct StrAccum StrAccum;
typedef struct Table Table;
typedef struct TableLock TableLock;
typedef struct Token Token;
typedef struct TriggerPrg TriggerPrg;
typedef struct TriggerStep TriggerStep;
typedef struct Trigger Trigger;
typedef struct UnpackedRecord UnpackedRecord;
typedef struct VTable VTable;
typedef struct Walker Walker;
typedef struct WherePlan WherePlan;
typedef struct WhereInfo WhereInfo;
typedef struct WhereLevel WhereLevel;

/*
** Defer sourcing vdbe.h and btree.h until after the "u8" and
** "BusyHandler" typedefs. vdbe.h also requires a few of the opaque
** pointer types (i.e. FuncDef) defined above.
*/
/************** Include btree.h in the middle of sqliteInt.h *****************/
/************** Begin file btree.h *******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite B-Tree file
** subsystem.  See comments in the source code for a detailed description
** of what each interface routine does.
*/
#ifndef _BTREE_H_
#define _BTREE_H_

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/
#define SQLITE_N_BTREE_META 10

/*
** If defined as non-zero, auto-vacuum is enabled by default. Otherwise
** it must be turned on for each database using "PRAGMA auto_vacuum = 1".
*/
#ifndef SQLITE_DEFAULT_AUTOVACUUM
  #define SQLITE_DEFAULT_AUTOVACUUM 0
#endif

#define BTREE_AUTOVACUUM_NONE 0        /* Do not do auto-vacuum */
#define BTREE_AUTOVACUUM_FULL 1        /* Do full auto-vacuum */
#define BTREE_AUTOVACUUM_INCR 2        /* Incremental vacuum */

/*
** Forward declarations of structure
*/
typedef struct Btree Btree;
typedef struct BtCursor BtCursor;
typedef struct BtShared BtShared;
typedef struct BtreeMutexArray BtreeMutexArray;

/*
** This structure records all of the Btrees that need to hold
** a mutex before we enter sqlite3VdbeExec().  The Btrees are
** are placed in aBtree[] in order of aBtree[]->pBt.  That way,
** we can always lock and unlock them all quickly.
*/
struct BtreeMutexArray {
  int nMutex;
  Btree *aBtree[SQLITE_MAX_ATTACHED+1];
};


SQLITE_PRIVATE int sqlite3BtreeOpen(
  const char *zFilename,   /* Name of database file to open */
  sqlite3 *db,             /* Associated database connection */
  Btree **ppBtree,         /* Return open Btree* here */
  int flags,               /* Flags */
  int vfsFlags             /* Flags passed through to VFS open */
);

/* The flags parameter to sqlite3BtreeOpen can be the bitwise or of the
** following values.
**
** NOTE:  These values must match the corresponding PAGER_ values in
** pager.h.
*/
#define BTREE_OMIT_JOURNAL  1  /* Do not use journal.  No argument */
#define BTREE_NO_READLOCK   2  /* Omit readlocks on readonly files */
#define BTREE_MEMORY        4  /* In-memory DB.  No argument */
#define BTREE_READONLY      8  /* Open the database in read-only mode */
#define BTREE_READWRITE    16  /* Open for both reading and writing */
#define BTREE_CREATE       32  /* Create the database if it does not exist */

SQLITE_PRIVATE int sqlite3BtreeClose(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetCacheSize(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeSetSafetyLevel(Btree*,int,int);
SQLITE_PRIVATE int sqlite3BtreeSyncDisabled(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetPageSize(Btree *p, int nPagesize, int nReserve, int eFix);
SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree*);
SQLITE_PRIVATE int sqlite3BtreeMaxPageCount(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeGetReserve(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *, int);
SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *);
SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree*, const char *zMaster);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree*);
SQLITE_PRIVATE int sqlite3BtreeCommit(Btree*);
SQLITE_PRIVATE int sqlite3BtreeRollback(Btree*);
SQLITE_PRIVATE int sqlite3BtreeBeginStmt(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeCreateTable(Btree*, int*, int flags);
SQLITE_PRIVATE int sqlite3BtreeIsInTrans(Btree*);
SQLITE_PRIVATE int sqlite3BtreeIsInReadTrans(Btree*);
SQLITE_PRIVATE int sqlite3BtreeIsInBackup(Btree*);
SQLITE_PRIVATE void *sqlite3BtreeSchema(Btree *, int, void(*)(void *));
SQLITE_PRIVATE int sqlite3BtreeSchemaLocked(Btree *pBtree);
SQLITE_PRIVATE int sqlite3BtreeLockTable(Btree *pBtree, int iTab, u8 isWriteLock);
SQLITE_PRIVATE int sqlite3BtreeSavepoint(Btree *, int, int);

SQLITE_PRIVATE const char *sqlite3BtreeGetFilename(Btree *);
SQLITE_PRIVATE const char *sqlite3BtreeGetJournalname(Btree *);
SQLITE_PRIVATE int sqlite3BtreeCopyFile(Btree *, Btree *);

SQLITE_PRIVATE int sqlite3BtreeIncrVacuum(Btree *);

/* The flags parameter to sqlite3BtreeCreateTable can be the bitwise OR
** of the following flags:
*/
#define BTREE_INTKEY     1    /* Table has only 64-bit signed integer keys */
#define BTREE_ZERODATA   2    /* Table has keys only - no data */
#define BTREE_LEAFDATA   4    /* Data stored in leaves only.  Implies INTKEY */

SQLITE_PRIVATE int sqlite3BtreeDropTable(Btree*, int, int*);
SQLITE_PRIVATE int sqlite3BtreeClearTable(Btree*, int, int*);
SQLITE_PRIVATE void sqlite3BtreeTripAllCursors(Btree*, int);

SQLITE_PRIVATE void sqlite3BtreeGetMeta(Btree *pBtree, int idx, u32 *pValue);
SQLITE_PRIVATE int sqlite3BtreeUpdateMeta(Btree*, int idx, u32 value);

/*
** The second parameter to sqlite3BtreeGetMeta or sqlite3BtreeUpdateMeta
** should be one of the following values. The integer values are assigned
** to constants so that the offset of the corresponding field in an
** SQLite database header may be found using the following formula:
**
**   offset = 36 + (idx * 4)
**
** For example, the free-page-count field is located at byte offset 36 of
** the database file header. The incr-vacuum-flag field is located at
** byte offset 64 (== 36+4*7).
*/
#define BTREE_FREE_PAGE_COUNT     0
#define BTREE_SCHEMA_VERSION      1
#define BTREE_FILE_FORMAT         2
#define BTREE_DEFAULT_CACHE_SIZE  3
#define BTREE_LARGEST_ROOT_PAGE   4
#define BTREE_TEXT_ENCODING       5
#define BTREE_USER_VERSION        6
#define BTREE_INCR_VACUUM         7

SQLITE_PRIVATE int sqlite3BtreeCursor(
  Btree*,                              /* BTree containing table to open */
  int iTable,                          /* Index of root page */
  int wrFlag,                          /* 1 for writing.  0 for read-only */
  struct KeyInfo*,                     /* First argument to compare function */
  BtCursor *pCursor                    /* Space to write cursor structure */
);
SQLITE_PRIVATE int sqlite3BtreeCursorSize(void);
SQLITE_PRIVATE void sqlite3BtreeCursorZero(BtCursor*);

SQLITE_PRIVATE int sqlite3BtreeCloseCursor(BtCursor*);
SQLITE_PRIVATE int sqlite3BtreeMovetoUnpacked(
  BtCursor*,
  UnpackedRecord *pUnKey,
  i64 intKey,
  int bias,
  int *pRes
);
SQLITE_PRIVATE int sqlite3BtreeCursorHasMoved(BtCursor*, int*);
SQLITE_PRIVATE int sqlite3BtreeDelete(BtCursor*);
SQLITE_PRIVATE int sqlite3BtreeInsert(BtCursor*, const void *pKey, i64 nKey,
                                  const void *pData, int nData,
                                  int nZero, int bias, int seekResult);
SQLITE_PRIVATE int sqlite3BtreeFirst(BtCursor*, int *pRes);
SQLITE_PRIVATE int sqlite3BtreeLast(BtCursor*, int *pRes);
SQLITE_PRIVATE int sqlite3BtreeNext(BtCursor*, int *pRes);
SQLITE_PRIVATE int sqlite3BtreeEof(BtCursor*);
SQLITE_PRIVATE int sqlite3BtreePrevious(BtCursor*, int *pRes);
SQLITE_PRIVATE int sqlite3BtreeKeySize(BtCursor*, i64 *pSize);
SQLITE_PRIVATE int sqlite3BtreeKey(BtCursor*, u32 offset, u32 amt, void*);
SQLITE_PRIVATE const void *sqlite3BtreeKeyFetch(BtCursor*, int *pAmt);
SQLITE_PRIVATE const void *sqlite3BtreeDataFetch(BtCursor*, int *pAmt);
SQLITE_PRIVATE int sqlite3BtreeDataSize(BtCursor*, u32 *pSize);
SQLITE_PRIVATE int sqlite3BtreeData(BtCursor*, u32 offset, u32 amt, void*);
SQLITE_PRIVATE void sqlite3BtreeSetCachedRowid(BtCursor*, sqlite3_int64);
SQLITE_PRIVATE sqlite3_int64 sqlite3BtreeGetCachedRowid(BtCursor*);

SQLITE_PRIVATE char *sqlite3BtreeIntegrityCheck(Btree*, int *aRoot, int nRoot, int, int*);
SQLITE_PRIVATE struct Pager *sqlite3BtreePager(Btree*);

SQLITE_PRIVATE int sqlite3BtreePutData(BtCursor*, u32 offset, u32 amt, void*);
SQLITE_PRIVATE void sqlite3BtreeCacheOverflow(BtCursor *);
SQLITE_PRIVATE void sqlite3BtreeClearCursor(BtCursor *);

#ifndef NDEBUG
SQLITE_PRIVATE int sqlite3BtreeCursorIsValid(BtCursor*);
#endif

#ifndef SQLITE_OMIT_BTREECOUNT
SQLITE_PRIVATE int sqlite3BtreeCount(BtCursor *, i64 *);
#endif

#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3BtreeCursorInfo(BtCursor*, int*, int);
SQLITE_PRIVATE void sqlite3BtreeCursorList(Btree*);
#endif

/*
** If we are not using shared cache, then there is no need to
** use mutexes to access the BtShared structures.  So make the
** Enter and Leave procedures no-ops.
*/
#ifndef SQLITE_OMIT_SHARED_CACHE
SQLITE_PRIVATE   void sqlite3BtreeEnter(Btree*);
SQLITE_PRIVATE   void sqlite3BtreeEnterAll(sqlite3*);
#else
# define sqlite3BtreeEnter(X)
# define sqlite3BtreeEnterAll(X)
#endif

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE
SQLITE_PRIVATE   void sqlite3BtreeLeave(Btree*);
SQLITE_PRIVATE   void sqlite3BtreeEnterCursor(BtCursor*);
SQLITE_PRIVATE   void sqlite3BtreeLeaveCursor(BtCursor*);
SQLITE_PRIVATE   void sqlite3BtreeLeaveAll(sqlite3*);
SQLITE_PRIVATE   void sqlite3BtreeMutexArrayEnter(BtreeMutexArray*);
SQLITE_PRIVATE   void sqlite3BtreeMutexArrayLeave(BtreeMutexArray*);
SQLITE_PRIVATE   void sqlite3BtreeMutexArrayInsert(BtreeMutexArray*, Btree*);
#ifndef NDEBUG
  /* These routines are used inside assert() statements only. */
SQLITE_PRIVATE   int sqlite3BtreeHoldsMutex(Btree*);
SQLITE_PRIVATE   int sqlite3BtreeHoldsAllMutexes(sqlite3*);
#endif
#else

# define sqlite3BtreeLeave(X)
# define sqlite3BtreeEnterCursor(X)
# define sqlite3BtreeLeaveCursor(X)
# define sqlite3BtreeLeaveAll(X)
# define sqlite3BtreeMutexArrayEnter(X)
# define sqlite3BtreeMutexArrayLeave(X)
# define sqlite3BtreeMutexArrayInsert(X,Y)

# define sqlite3BtreeHoldsMutex(X) 1
# define sqlite3BtreeHoldsAllMutexes(X) 1
#endif


#endif /* _BTREE_H_ */

/************** End of btree.h ***********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/
/************** Include vdbe.h in the middle of sqliteInt.h ******************/
/************** Begin file vdbe.h ********************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Header file for the Virtual DataBase Engine (VDBE)
**
** This header defines the interface to the virtual database engine
** or VDBE.  The VDBE implements an abstract machine that runs a
** simple program to access and modify the underlying database.
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_

/*
** A single VDBE is an opaque structure named "Vdbe".  Only routines
** in the source file sqliteVdbe.c are allowed to see the insides
** of this structure.
*/
typedef struct Vdbe Vdbe;

/*
** The names of the following types declared in vdbeInt.h are required
** for the VdbeOp definition.
*/
typedef struct VdbeFunc VdbeFunc;
typedef struct Mem Mem;
typedef struct SubProgram SubProgram;

/*
** A single instruction of the virtual machine has an opcode
** and as many as three operands.  The instruction is recorded
** as an instance of the following structure:
*/
struct VdbeOp {
  u8 opcode;          /* What operation to perform */
  signed char p4type; /* One of the P4_xxx constants for p4 */
  u8 opflags;         /* Mask of the OPFLG_* flags in opcodes.h */
  u8 p5;              /* Fifth parameter is an unsigned character */
  int p1;             /* First operand */
  int p2;             /* Second parameter (often the jump destination) */
  int p3;             /* The third parameter */
  union {             /* fourth parameter */
    int i;                 /* Integer value if p4type==P4_INT32 */
    void *p;               /* Generic pointer */
    char *z;               /* Pointer to data for string (char array) types */
    i64 *pI64;             /* Used when p4type is P4_INT64 */
    double *pReal;         /* Used when p4type is P4_REAL */
    FuncDef *pFunc;        /* Used when p4type is P4_FUNCDEF */
    VdbeFunc *pVdbeFunc;   /* Used when p4type is P4_VDBEFUNC */
    CollSeq *pColl;        /* Used when p4type is P4_COLLSEQ */
    Mem *pMem;             /* Used when p4type is P4_MEM */
    VTable *pVtab;         /* Used when p4type is P4_VTAB */
    KeyInfo *pKeyInfo;     /* Used when p4type is P4_KEYINFO */
    int *ai;               /* Used when p4type is P4_INTARRAY */
    SubProgram *pProgram;  /* Used when p4type is P4_SUBPROGRAM */
  } p4;
#ifdef SQLITE_DEBUG
  char *zComment;          /* Comment to improve readability */
#endif
#ifdef VDBE_PROFILE
  int cnt;                 /* Number of times this instruction was executed */
  u64 cycles;              /* Total time spent executing this instruction */
#endif
};
typedef struct VdbeOp VdbeOp;


/*
** A sub-routine used to implement a trigger program.
*/
struct SubProgram {
  VdbeOp *aOp;                  /* Array of opcodes for sub-program */
  int nOp;                      /* Elements in aOp[] */
  int nMem;                     /* Number of memory cells required */
  int nCsr;                     /* Number of cursors required */
  int nRef;                     /* Number of pointers to this structure */
  void *token;                  /* id that may be used to recursive triggers */
};

/*
** A smaller version of VdbeOp used for the VdbeAddOpList() function because
** it takes up less space.
*/
struct VdbeOpList {
  u8 opcode;          /* What operation to perform */
  signed char p1;     /* First operand */
  signed char p2;     /* Second parameter (often the jump destination) */
  signed char p3;     /* Third parameter */
};
typedef struct VdbeOpList VdbeOpList;

/*
** Allowed values of VdbeOp.p4type
*/
#define P4_NOTUSED    0   /* The P4 parameter is not used */
#define P4_DYNAMIC  (-1)  /* Pointer to a string obtained from sqliteMalloc() */
#define P4_STATIC   (-2)  /* Pointer to a static string */
#define P4_COLLSEQ  (-4)  /* P4 is a pointer to a CollSeq structure */
#define P4_FUNCDEF  (-5)  /* P4 is a pointer to a FuncDef structure */
#define P4_KEYINFO  (-6)  /* P4 is a pointer to a KeyInfo structure */
#define P4_VDBEFUNC (-7)  /* P4 is a pointer to a VdbeFunc structure */
#define P4_MEM      (-8)  /* P4 is a pointer to a Mem*    structure */
#define P4_TRANSIENT (-9) /* P4 is a pointer to a transient string */
#define P4_VTAB     (-10) /* P4 is a pointer to an sqlite3_vtab structure */
#define P4_MPRINTF  (-11) /* P4 is a string obtained from sqlite3_mprintf() */
#define P4_REAL     (-12) /* P4 is a 64-bit floating point value */
#define P4_INT64    (-13) /* P4 is a 64-bit signed integer */
#define P4_INT32    (-14) /* P4 is a 32-bit signed integer */
#define P4_INTARRAY (-15) /* P4 is a vector of 32-bit integers */
#define P4_SUBPROGRAM  (-18) /* P4 is a pointer to a SubProgram structure */

/* When adding a P4 argument using P4_KEYINFO, a copy of the KeyInfo structure
** is made.  That copy is freed when the Vdbe is finalized.  But if the
** argument is P4_KEYINFO_HANDOFF, the passed in pointer is used.  It still
** gets freed when the Vdbe is finalized so it still should be obtained
** from a single sqliteMalloc().  But no copy is made and the calling
** function should *not* try to free the KeyInfo.
*/
#define P4_KEYINFO_HANDOFF (-16)
#define P4_KEYINFO_STATIC  (-17)

/*
** The Vdbe.aColName array contains 5n Mem structures, where n is the
** number of columns of data returned by the statement.
*/
#define COLNAME_NAME     0
#define COLNAME_DECLTYPE 1
#define COLNAME_DATABASE 2
#define COLNAME_TABLE    3
#define COLNAME_COLUMN   4
#ifdef SQLITE_ENABLE_COLUMN_METADATA
# define COLNAME_N        5      /* Number of COLNAME_xxx symbols */
#else
# ifdef SQLITE_OMIT_DECLTYPE
#   define COLNAME_N      1      /* Store only the name */
# else
#   define COLNAME_N      2      /* Store the name and decltype */
# endif
#endif

/*
** The following macro converts a relative address in the p2 field
** of a VdbeOp structure into a negative number so that
** sqlite3VdbeAddOpList() knows that the address is relative.  Calling
** the macro again restores the address.
*/
#define ADDR(X)  (-1-(X))

/*
** The makefile scans the vdbe.c source file and creates the "opcodes.h"
** header file that defines a number for each opcode used by the VDBE.
*/
/************** Include opcodes.h in the middle of vdbe.h ********************/
/************** Begin file opcodes.h *****************************************/
/* Automatically generated.  Do not edit */
/* See the mkopcodeh.awk script for details */
#define OP_Goto                                 1
#define OP_Gosub                                2
#define OP_Return                               3
#define OP_Yield                                4
#define OP_HaltIfNull                           5
#define OP_Halt                                 6
#define OP_Integer                              7
#define OP_Int64                                8
#define OP_Real                               130   /* same as TK_FLOAT    */
#define OP_String8                             94   /* same as TK_STRING   */
#define OP_String                               9
#define OP_Null                                10
#define OP_Blob                                11
#define OP_Variable                            12
#define OP_Move                                13
#define OP_Copy                                14
#define OP_SCopy                               15
#define OP_ResultRow                           16
#define OP_Concat                              91   /* same as TK_CONCAT   */
#define OP_Add                                 86   /* same as TK_PLUS     */
#define OP_Subtract                            87   /* same as TK_MINUS    */
#define OP_Multiply                            88   /* same as TK_STAR     */
#define OP_Divide                              89   /* same as TK_SLASH    */
#define OP_Remainder                           90   /* same as TK_REM      */
#define OP_CollSeq                             17
#define OP_Function                            18
#define OP_BitAnd                              82   /* same as TK_BITAND   */
#define OP_BitOr                               83   /* same as TK_BITOR    */
#define OP_ShiftLeft                           84   /* same as TK_LSHIFT   */
#define OP_ShiftRight                          85   /* same as TK_RSHIFT   */
#define OP_AddImm                              20
#define OP_MustBeInt                           21
#define OP_RealAffinity                        22
#define OP_ToText                             141   /* same as TK_TO_TEXT  */
#define OP_ToBlob                             142   /* same as TK_TO_BLOB  */
#define OP_ToNumeric                          143   /* same as TK_TO_NUMERIC*/
#define OP_ToInt                              144   /* same as TK_TO_INT   */
#define OP_ToReal                             145   /* same as TK_TO_REAL  */
#define OP_Eq                                  76   /* same as TK_EQ       */
#define OP_Ne                                  75   /* same as TK_NE       */
#define OP_Lt                                  79   /* same as TK_LT       */
#define OP_Le                                  78   /* same as TK_LE       */
#define OP_Gt                                  77   /* same as TK_GT       */
#define OP_Ge                                  80   /* same as TK_GE       */
#define OP_Permutation                         23
#define OP_Compare                             24
#define OP_Jump                                25
#define OP_And                                 69   /* same as TK_AND      */
#define OP_Or                                  68   /* same as TK_OR       */
#define OP_Not                                 19   /* same as TK_NOT      */
#define OP_BitNot                              93   /* same as TK_BITNOT   */
#define OP_If                                  26
#define OP_IfNot                               27
#define OP_IsNull                              73   /* same as TK_ISNULL   */
#define OP_NotNull                             74   /* same as TK_NOTNULL  */
#define OP_Column                              28
#define OP_Affinity                            29
#define OP_MakeRecord                          30
#define OP_Count                               31
#define OP_Savepoint                           32
#define OP_AutoCommit                          33
#define OP_Transaction                         34
#define OP_ReadCookie                          35
#define OP_SetCookie                           36
#define OP_VerifyCookie                        37
#define OP_OpenRead                            38
#define OP_OpenWrite                           39
#define OP_OpenEphemeral                       40
#define OP_OpenPseudo                          41
#define OP_Close                               42
#define OP_SeekLt                              43
#define OP_SeekLe                              44
#define OP_SeekGe                              45
#define OP_SeekGt                              46
#define OP_Seek                                47
#define OP_NotFound                            48
#define OP_Found                               49
#define OP_IsUnique                            50
#define OP_NotExists                           51
#define OP_Sequence                            52
#define OP_NewRowid                            53
#define OP_Insert                              54
#define OP_InsertInt                           55
#define OP_Delete                              56
#define OP_ResetCount                          57
#define OP_RowKey                              58
#define OP_RowData                             59
#define OP_Rowid                               60
#define OP_NullRow                             61
#define OP_Last                                62
#define OP_Sort                                63
#define OP_Rewind                              64
#define OP_Prev                                65
#define OP_Next                                66
#define OP_IdxInsert                           67
#define OP_IdxDelete                           70
#define OP_IdxRowid                            71
#define OP_IdxLT                               72
#define OP_IdxGE                               81
#define OP_Destroy                             92
#define OP_Clear                               95
#define OP_CreateIndex                         96
#define OP_CreateTable                         97
#define OP_ParseSchema                         98
#define OP_LoadAnalysis                        99
#define OP_DropTable                          100
#define OP_DropIndex                          101
#define OP_DropTrigger                        102
#define OP_IntegrityCk                        103
#define OP_RowSetAdd                          104
#define OP_RowSetRead                         105
#define OP_RowSetTest                         106
#define OP_Program                            107
#define OP_Param                              108
#define OP_FkCounter                          109
#define OP_FkIfZero                           110
#define OP_MemMax                             111
#define OP_IfPos                              112
#define OP_IfNeg                              113
#define OP_IfZero                             114
#define OP_AggStep                            115
#define OP_AggFinal                           116
#define OP_Vacuum                             117
#define OP_IncrVacuum                         118
#define OP_Expire                             119
#define OP_TableLock                          120
#define OP_VBegin                             121
#define OP_VCreate                            122
#define OP_VDestroy                           123
#define OP_VOpen                              124
#define OP_VFilter                            125
#define OP_VColumn                            126
#define OP_VNext                              127
#define OP_VRename                            128
#define OP_VUpdate                            129
#define OP_Pagecount                          131
#define OP_Trace                              132
#define OP_Noop                               133
#define OP_Explain                            134

/* The following opcode values are never used */
#define OP_NotUsed_135                        135
#define OP_NotUsed_136                        136
#define OP_NotUsed_137                        137
#define OP_NotUsed_138                        138
#define OP_NotUsed_139                        139
#define OP_NotUsed_140                        140


/* Properties such as "out2" or "jump" that are specified in
** comments following the "case" for each opcode in the vdbe.c
** are encoded into bitvectors as follows:
*/
#define OPFLG_JUMP            0x0001  /* jump:  P2 holds jmp target */
#define OPFLG_OUT2_PRERELEASE 0x0002  /* out2-prerelease: */
#define OPFLG_IN1             0x0004  /* in1:   P1 is an input */
#define OPFLG_IN2             0x0008  /* in2:   P2 is an input */
#define OPFLG_IN3             0x0010  /* in3:   P3 is an input */
#define OPFLG_OUT2            0x0020  /* out2:  P2 is an output */
#define OPFLG_OUT3            0x0040  /* out3:  P3 is an output */
#define OPFLG_INITIALIZER {\
/*   0 */ 0x00, 0x01, 0x05, 0x04, 0x04, 0x10, 0x00, 0x02,\
/*   8 */ 0x02, 0x02, 0x02, 0x02, 0x00, 0x00, 0x24, 0x24,\
/*  16 */ 0x00, 0x00, 0x00, 0x24, 0x04, 0x05, 0x04, 0x00,\
/*  24 */ 0x00, 0x01, 0x05, 0x05, 0x00, 0x00, 0x00, 0x02,\
/*  32 */ 0x00, 0x00, 0x00, 0x02, 0x10, 0x00, 0x00, 0x00,\
/*  40 */ 0x00, 0x00, 0x00, 0x11, 0x11, 0x11, 0x11, 0x08,\
/*  48 */ 0x11, 0x11, 0x11, 0x11, 0x02, 0x02, 0x00, 0x00,\
/*  56 */ 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x01, 0x01,\
/*  64 */ 0x01, 0x01, 0x01, 0x08, 0x4c, 0x4c, 0x00, 0x02,\
/*  72 */ 0x01, 0x05, 0x05, 0x15, 0x15, 0x15, 0x15, 0x15,\
/*  80 */ 0x15, 0x01, 0x4c, 0x4c, 0x4c, 0x4c, 0x4c, 0x4c,\
/*  88 */ 0x4c, 0x4c, 0x4c, 0x4c, 0x02, 0x24, 0x02, 0x00,\
/*  96 */ 0x02, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
/* 104 */ 0x0c, 0x45, 0x15, 0x01, 0x02, 0x00, 0x01, 0x08,\
/* 112 */ 0x05, 0x05, 0x05, 0x00, 0x00, 0x00, 0x01, 0x00,\
/* 120 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01,\
/* 128 */ 0x00, 0x00, 0x02, 0x02, 0x00, 0x00, 0x00, 0x00,\
/* 136 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x04, 0x04,\
/* 144 */ 0x04, 0x04,}

/************** End of opcodes.h *********************************************/
/************** Continuing where we left off in vdbe.h ***********************/

/*
** Prototypes for the VDBE interface.  See comments on the implementation
** for a description of what each of these routines does.
*/
SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(sqlite3*);
SQLITE_PRIVATE int sqlite3VdbeAddOp0(Vdbe*,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp1(Vdbe*,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp2(Vdbe*,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp3(Vdbe*,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4(Vdbe*,int,int,int,int,const char *zP4,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(Vdbe*,int,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp);
SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe*, int addr, int P3);
SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe*, u8 P5);
SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe*, int addr);
SQLITE_PRIVATE void sqlite3VdbeChangeToNoop(Vdbe*, int addr, int N);
SQLITE_PRIVATE void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe*, int);
SQLITE_PRIVATE VdbeOp *sqlite3VdbeGetOp(Vdbe*, int);
SQLITE_PRIVATE int sqlite3VdbeMakeLabel(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeRunOnlyOnce(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeDelete(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeMakeReady(Vdbe*,int,int,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeFinalize(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeResolveLabel(Vdbe*, int);
SQLITE_PRIVATE int sqlite3VdbeCurrentAddr(Vdbe*);
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   int sqlite3VdbeAssertMayAbort(Vdbe *, int);
SQLITE_PRIVATE   void sqlite3VdbeTrace(Vdbe*,FILE*);
#endif
SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe*);
SQLITE_PRIVATE int sqlite3VdbeReset(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeSetNumCols(Vdbe*,int);
SQLITE_PRIVATE int sqlite3VdbeSetColName(Vdbe*, int, int, const char *, void(*)(void*));
SQLITE_PRIVATE void sqlite3VdbeCountChanges(Vdbe*);
SQLITE_PRIVATE sqlite3 *sqlite3VdbeDb(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeSetSql(Vdbe*, const char *z, int n, int);
SQLITE_PRIVATE void sqlite3VdbeSwap(Vdbe*,Vdbe*);
SQLITE_PRIVATE VdbeOp *sqlite3VdbeTakeOpArray(Vdbe*, int*, int*);
SQLITE_PRIVATE void sqlite3VdbeProgramDelete(sqlite3 *, SubProgram *, int);
SQLITE_PRIVATE sqlite3_value *sqlite3VdbeGetValue(Vdbe*, int, u8);
SQLITE_PRIVATE void sqlite3VdbeSetVarmask(Vdbe*, int);
#ifndef SQLITE_OMIT_TRACE
SQLITE_PRIVATE   char *sqlite3VdbeExpandSql(Vdbe*, const char*);
#endif

SQLITE_PRIVATE UnpackedRecord *sqlite3VdbeRecordUnpack(KeyInfo*,int,const void*,char*,int);
SQLITE_PRIVATE void sqlite3VdbeDeleteUnpackedRecord(UnpackedRecord*);
SQLITE_PRIVATE int sqlite3VdbeRecordCompare(int,const void*,UnpackedRecord*);


#ifndef NDEBUG
SQLITE_PRIVATE   void sqlite3VdbeComment(Vdbe*, const char*, ...);
# define VdbeComment(X)  sqlite3VdbeComment X
SQLITE_PRIVATE   void sqlite3VdbeNoopComment(Vdbe*, const char*, ...);
# define VdbeNoopComment(X)  sqlite3VdbeNoopComment X
#else
# define VdbeComment(X)
# define VdbeNoopComment(X)
#endif

#endif

/************** End of vdbe.h ************************************************/
/************** Continuing where we left off in sqliteInt.h ******************/
/************** Include pager.h in the middle of sqliteInt.h *****************/
/************** Begin file pager.h *******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem.  The page cache subsystem reads and writes a file a page
** at a time and provides a journal for rollback.
*/

#ifndef _PAGER_H_
#define _PAGER_H_

/*
** Default maximum size for persistent journal files. A negative
** value means no limit. This value may be overridden using the
** sqlite3PagerJournalSizeLimit() API. See also "PRAGMA journal_size_limit".
*/
#ifndef SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT
  #define SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT -1
#endif

/*
** The type used to represent a page number.  The first page in a file
** is called page 1.  0 is used to represent "not a page".
*/
typedef u32 Pgno;

/*
** Each open file is managed by a separate instance of the "Pager" structure.
*/
typedef struct Pager Pager;

/*
** Handle type for pages.
*/
typedef struct PgHdr DbPage;

/*
** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is
** reserved for working around a windows/posix incompatibility). It is
** used in the journal to signify that the remainder of the journal file
** is devoted to storing a master journal name - there are no more pages to
** roll back. See comments for function writeMasterJournal() in pager.c
** for details.
*/
#define PAGER_MJ_PGNO(x) ((Pgno)((PENDING_BYTE/((x)->pageSize))+1))

/*
** Allowed values for the flags parameter to sqlite3PagerOpen().
**
** NOTE: These values must match the corresponding BTREE_ values in btree.h.
*/
#define PAGER_OMIT_JOURNAL  0x0001    /* Do not use a rollback journal */
#define PAGER_NO_READLOCK   0x0002    /* Omit readlocks on readonly files */

/*
** Valid values for the second argument to sqlite3PagerLockingMode().
*/
#define PAGER_LOCKINGMODE_QUERY      -1
#define PAGER_LOCKINGMODE_NORMAL      0
#define PAGER_LOCKINGMODE_EXCLUSIVE   1

/*
** Valid values for the second argument to sqlite3PagerJournalMode().
*/
#define PAGER_JOURNALMODE_QUERY      -1
#define PAGER_JOURNALMODE_DELETE      0   /* Commit by deleting journal file */
#define PAGER_JOURNALMODE_PERSIST     1   /* Commit by zeroing journal header */
#define PAGER_JOURNALMODE_OFF         2   /* Journal omitted.  */
#define PAGER_JOURNALMODE_TRUNCATE    3   /* Commit by truncating journal */
#define PAGER_JOURNALMODE_MEMORY      4   /* In-memory journal file */

/*
** The remainder of this file contains the declarations of the functions
** that make up the Pager sub-system API. See source code comments for
** a detailed description of each routine.
*/

/* Open and close a Pager connection. */
SQLITE_PRIVATE int sqlite3PagerOpen(
  sqlite3_vfs*,
  Pager **ppPager,
  const char*,
  int,
  int,
  int,
  void(*)(DbPage*)
);
SQLITE_PRIVATE int sqlite3PagerClose(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerReadFileheader(Pager*, int, unsigned char*);

/* Functions used to configure a Pager object. */
SQLITE_PRIVATE void sqlite3PagerSetBusyhandler(Pager*, int(*)(void *), void *);
SQLITE_PRIVATE int sqlite3PagerSetPagesize(Pager*, u16*, int);
SQLITE_PRIVATE int sqlite3PagerMaxPageCount(Pager*, int);
SQLITE_PRIVATE void sqlite3PagerSetCachesize(Pager*, int);
SQLITE_PRIVATE void sqlite3PagerSetSafetyLevel(Pager*,int,int);
SQLITE_PRIVATE int sqlite3PagerLockingMode(Pager *, int);
SQLITE_PRIVATE int sqlite3PagerJournalMode(Pager *, int);
SQLITE_PRIVATE i64 sqlite3PagerJournalSizeLimit(Pager *, i64);
SQLITE_PRIVATE sqlite3_backup **sqlite3PagerBackupPtr(Pager*);

/* Functions used to obtain and release page references. */
SQLITE_PRIVATE int sqlite3PagerAcquire(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag);
#define sqlite3PagerGet(A,B,C) sqlite3PagerAcquire(A,B,C,0)
SQLITE_PRIVATE DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno);
SQLITE_PRIVATE void sqlite3PagerRef(DbPage*);
SQLITE_PRIVATE void sqlite3PagerUnref(DbPage*);

/* Operations on page references. */
SQLITE_PRIVATE int sqlite3PagerWrite(DbPage*);
SQLITE_PRIVATE void sqlite3PagerDontWrite(DbPage*);
SQLITE_PRIVATE int sqlite3PagerMovepage(Pager*,DbPage*,Pgno,int);
SQLITE_PRIVATE int sqlite3PagerPageRefcount(DbPage*);
SQLITE_PRIVATE void *sqlite3PagerGetData(DbPage *);
SQLITE_PRIVATE void *sqlite3PagerGetExtra(DbPage *);

/* Functions used to manage pager transactions and savepoints. */
SQLITE_PRIVATE int sqlite3PagerPagecount(Pager*, int*);
SQLITE_PRIVATE int sqlite3PagerBegin(Pager*, int exFlag, int);
SQLITE_PRIVATE int sqlite3PagerCommitPhaseOne(Pager*,const char *zMaster, int);
SQLITE_PRIVATE int sqlite3PagerSync(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerCommitPhaseTwo(Pager*);
SQLITE_PRIVATE int sqlite3PagerRollback(Pager*);
SQLITE_PRIVATE int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
SQLITE_PRIVATE int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
SQLITE_PRIVATE int sqlite3PagerSharedLock(Pager *pPager);

/* Functions used to query pager state and configuration. */
SQLITE_PRIVATE u8 sqlite3PagerIsreadonly(Pager*);
SQLITE_PRIVATE int sqlite3PagerRefcount(Pager*);
SQLITE_PRIVATE const char *sqlite3PagerFilename(Pager*);
SQLITE_PRIVATE const sqlite3_vfs *sqlite3PagerVfs(Pager*);
SQLITE_PRIVATE sqlite3_file *sqlite3PagerFile(Pager*);
SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager*);
SQLITE_PRIVATE int sqlite3PagerNosync(Pager*);
SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager*);
SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager*);

/* Functions used to truncate the database file. */
SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager*,Pgno);

/* Functions to support testing and debugging. */
#if !defined(NDEBUG) || defined(SQLITE_TEST)
SQLITE_PRIVATE   Pgno sqlite3PagerPagenumber(DbPage*);
SQLITE_PRIVATE   int sqlite3PagerIswriteable(DbPage*);
#endif
#ifdef SQLITE_TEST
SQLITE_PRIVATE   int *sqlite3PagerStats(Pager*);
SQLITE_PRIVATE   void sqlite3PagerRefdump(Pager*);
  void disable_simulated_io_errors(void);
  void enable_simulated_io_errors(void);
#else
# define disable_simulated_io_errors()
# define enable_simulated_io_errors()
#endif

#endif /* _PAGER_H_ */

/************** End of pager.h ***********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/
/************** Include pcache.h in the middle of sqliteInt.h ****************/
/************** Begin file pcache.h ******************************************/
/*
** 2008 August 05
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem.
*/

#ifndef _PCACHE_H_

typedef struct PgHdr PgHdr;
typedef struct PCache PCache;

/*
** Every page in the cache is controlled by an instance of the following
** structure.
*/
struct PgHdr {
  void *pData;                   /* Content of this page */
  void *pExtra;                  /* Extra content */
  PgHdr *pDirty;                 /* Transient list of dirty pages */
  Pgno pgno;                     /* Page number for this page */
  Pager *pPager;                 /* The pager this page is part of */
#ifdef SQLITE_CHECK_PAGES
  u32 pageHash;                  /* Hash of page content */
#endif
  u16 flags;                     /* PGHDR flags defined below */

  /**********************************************************************
  ** Elements above are public.  All that follows is private to pcache.c
  ** and should not be accessed by other modules.
  */
  i16 nRef;                      /* Number of users of this page */
  PCache *pCache;                /* Cache that owns this page */

  PgHdr *pDirtyNext;             /* Next element in list of dirty pages */
  PgHdr *pDirtyPrev;             /* Previous element in list of dirty pages */
};

/* Bit values for PgHdr.flags */
#define PGHDR_DIRTY             0x002  /* Page has changed */
#define PGHDR_NEED_SYNC         0x004  /* Fsync the rollback journal before
                                       ** writing this page to the database */
#define PGHDR_NEED_READ         0x008  /* Content is unread */
#define PGHDR_REUSE_UNLIKELY    0x010  /* A hint that reuse is unlikely */
#define PGHDR_DONT_WRITE        0x020  /* Do not write content to disk */

/* Initialize and shutdown the page cache subsystem */
SQLITE_PRIVATE int sqlite3PcacheInitialize(void);
SQLITE_PRIVATE void sqlite3PcacheShutdown(void);

/* Page cache buffer management:
** These routines implement SQLITE_CONFIG_PAGECACHE.
*/
SQLITE_PRIVATE void sqlite3PCacheBufferSetup(void *, int sz, int n);

/* Create a new pager cache.
** Under memory stress, invoke xStress to try to make pages clean.
** Only clean and unpinned pages can be reclaimed.
*/
SQLITE_PRIVATE void sqlite3PcacheOpen(
  int szPage,                    /* Size of every page */
  int szExtra,                   /* Extra space associated with each page */
  int bPurgeable,                /* True if pages are on backing store */
  int (*xStress)(void*, PgHdr*), /* Call to try to make pages clean */
  void *pStress,                 /* Argument to xStress */
  PCache *pToInit                /* Preallocated space for the PCache */
);

/* Modify the page-size after the cache has been created. */
SQLITE_PRIVATE void sqlite3PcacheSetPageSize(PCache *, int);

/* Return the size in bytes of a PCache object.  Used to preallocate
** storage space.
*/
SQLITE_PRIVATE int sqlite3PcacheSize(void);

/* One release per successful fetch.  Page is pinned until released.
** Reference counted.
*/
SQLITE_PRIVATE int sqlite3PcacheFetch(PCache*, Pgno, int createFlag, PgHdr**);
SQLITE_PRIVATE void sqlite3PcacheRelease(PgHdr*);

SQLITE_PRIVATE void sqlite3PcacheDrop(PgHdr*);         /* Remove page from cache */
SQLITE_PRIVATE void sqlite3PcacheMakeDirty(PgHdr*);    /* Make sure page is marked dirty */
SQLITE_PRIVATE void sqlite3PcacheMakeClean(PgHdr*);    /* Mark a single page as clean */
SQLITE_PRIVATE void sqlite3PcacheCleanAll(PCache*);    /* Mark all dirty list pages as clean */

/* Change a page number.  Used by incr-vacuum. */
SQLITE_PRIVATE void sqlite3PcacheMove(PgHdr*, Pgno);

/* Remove all pages with pgno>x.  Reset the cache if x==0 */
SQLITE_PRIVATE void sqlite3PcacheTruncate(PCache*, Pgno x);

/* Get a list of all dirty pages in the cache, sorted by page number */
SQLITE_PRIVATE PgHdr *sqlite3PcacheDirtyList(PCache*);

/* Reset and close the cache object */
SQLITE_PRIVATE void sqlite3PcacheClose(PCache*);

/* Clear flags from pages of the page cache */
SQLITE_PRIVATE void sqlite3PcacheClearSyncFlags(PCache *);

/* Discard the contents of the cache */
SQLITE_PRIVATE void sqlite3PcacheClear(PCache*);

/* Return the total number of outstanding page references */
SQLITE_PRIVATE int sqlite3PcacheRefCount(PCache*);

/* Increment the reference count of an existing page */
SQLITE_PRIVATE void sqlite3PcacheRef(PgHdr*);

SQLITE_PRIVATE int sqlite3PcachePageRefcount(PgHdr*);

/* Return the total number of pages stored in the cache */
SQLITE_PRIVATE int sqlite3PcachePagecount(PCache*);

#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
/* Iterate through all dirty pages currently stored in the cache. This
** interface is only available if SQLITE_CHECK_PAGES is defined when the
** library is built.
*/
SQLITE_PRIVATE void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *));
#endif

/* Set and get the suggested cache-size for the specified pager-cache.
**
** If no global maximum is configured, then the system attempts to limit
** the total number of pages cached by purgeable pager-caches to the sum
** of the suggested cache-sizes.
*/
SQLITE_PRIVATE void sqlite3PcacheSetCachesize(PCache *, int);
#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3PcacheGetCachesize(PCache *);
#endif

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
/* Try to return memory used by the pcache module to the main memory heap */
SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int);
#endif

#ifdef SQLITE_TEST
SQLITE_PRIVATE void sqlite3PcacheStats(int*,int*,int*,int*);
#endif

SQLITE_PRIVATE void sqlite3PCacheSetDefault(void);

#endif /* _PCACHE_H_ */

/************** End of pcache.h **********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/

/************** Include os.h in the middle of sqliteInt.h ********************/
/************** Begin file os.h **********************************************/
/*
** 2001 September 16
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This header file (together with is companion C source-code file
** "os.c") attempt to abstract the underlying operating system so that
** the SQLite library will work on both POSIX and windows systems.
**
** This header file is #include-ed by sqliteInt.h and thus ends up
** being included by every source file.
*/
#ifndef _SQLITE_OS_H_
#define _SQLITE_OS_H_

/*
** Figure out if we are dealing with Unix, Windows, or some other
** operating system.  After the following block of preprocess macros,
** all of SQLITE_OS_UNIX, SQLITE_OS_WIN, SQLITE_OS_OS2, and SQLITE_OS_OTHER
** will defined to either 1 or 0.  One of the four will be 1.  The other
** three will be 0.
*/
#if defined(SQLITE_OS_OTHER)
# if SQLITE_OS_OTHER==1
#   undef SQLITE_OS_UNIX
#   define SQLITE_OS_UNIX 0
#   undef SQLITE_OS_WIN
#   define SQLITE_OS_WIN 0
#   undef SQLITE_OS_OS2
#   define SQLITE_OS_OS2 0
# else
#   undef SQLITE_OS_OTHER
# endif
#endif
#if !defined(SQLITE_OS_UNIX) && !defined(SQLITE_OS_OTHER)
# define SQLITE_OS_OTHER 0
# ifndef SQLITE_OS_WIN
#   if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__BORLANDC__)
#     define SQLITE_OS_WIN 1
#     define SQLITE_OS_UNIX 0
#     define SQLITE_OS_OS2 0
#   elif defined(__EMX__) || defined(_OS2) || defined(OS2) || defined(_OS2_) || defined(__OS2__)
#     define SQLITE_OS_WIN 0
#     define SQLITE_OS_UNIX 0
#     define SQLITE_OS_OS2 1
#   else
#     define SQLITE_OS_WIN 0
#     define SQLITE_OS_UNIX 1
#     define SQLITE_OS_OS2 0
#  endif
# else
#  define SQLITE_OS_UNIX 0
#  define SQLITE_OS_OS2 0
# endif
#else
# ifndef SQLITE_OS_WIN
#  define SQLITE_OS_WIN 0
# endif
#endif

/*
** Determine if we are dealing with WindowsCE - which has a much
** reduced API.
*/
#if defined(_WIN32_WCE)
# define SQLITE_OS_WINCE 1
#else
# define SQLITE_OS_WINCE 0
#endif


/*
** Define the maximum size of a temporary filename
*/
#if SQLITE_OS_WIN
# include <windows.h>
# define SQLITE_TEMPNAME_SIZE (MAX_PATH+50)
#elif SQLITE_OS_OS2
# if (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 3) && defined(OS2_HIGH_MEMORY)
#  include <os2safe.h> /* has to be included before os2.h for linking to work */
# endif
# define INCL_DOSDATETIME
# define INCL_DOSFILEMGR
# define INCL_DOSERRORS
# define INCL_DOSMISC
# define INCL_DOSPROCESS
# define INCL_DOSMODULEMGR
# define INCL_DOSSEMAPHORES
# include <os2.h>
# include <uconv.h>
# define SQLITE_TEMPNAME_SIZE (CCHMAXPATHCOMP)
#else
# define SQLITE_TEMPNAME_SIZE 200
#endif

/* If the SET_FULLSYNC macro is not defined above, then make it
** a no-op
*/
#ifndef SET_FULLSYNC
# define SET_FULLSYNC(x,y)
#endif

/*
** The default size of a disk sector
*/
#ifndef SQLITE_DEFAULT_SECTOR_SIZE
# define SQLITE_DEFAULT_SECTOR_SIZE 512
#endif

/*
** Temporary files are named starting with this prefix followed by 16 random
** alphanumeric characters, and no file extension. They are stored in the
** OS's standard temporary file directory, and are deleted prior to exit.
** If sqlite is being embedded in another program, you may wish to change the
** prefix to reflect your program's name, so that if your program exits
** prematurely, old temporary files can be easily identified. This can be done
** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line.
**
** 2006-10-31:  The default prefix used to be "sqlite_".  But then
** Mcafee started using SQLite in their anti-virus product and it
** started putting files with the "sqlite" name in the c:/temp folder.
** This annoyed many windows users.  Those users would then do a
** Google search for "sqlite", find the telephone numbers of the
** developers and call to wake them up at night and complain.
** For this reason, the default name prefix is changed to be "sqlite"
** spelled backwards.  So the temp files are still identified, but
** anybody smart enough to figure out the code is also likely smart
** enough to know that calling the developer will not help get rid
** of the file.
*/
#ifndef SQLITE_TEMP_FILE_PREFIX
# define SQLITE_TEMP_FILE_PREFIX "etilqs_"
#endif

/*
** The following values may be passed as the second argument to
** sqlite3OsLock(). The various locks exhibit the following semantics:
**
** SHARED:    Any number of processes may hold a SHARED lock simultaneously.
** RESERVED:  A single process may hold a RESERVED lock on a file at
**            any time. Other processes may hold and obtain new SHARED locks.
** PENDING:   A single process may hold a PENDING lock on a file at
**            any one time. Existing SHARED locks may persist, but no new
**            SHARED locks may be obtained by other processes.
** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks.
**
** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a
** process that requests an EXCLUSIVE lock may actually obtain a PENDING
** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to
** sqlite3OsLock().
*/
#define NO_LOCK         0
#define SHARED_LOCK     1
#define RESERVED_LOCK   2
#define PENDING_LOCK    3
#define EXCLUSIVE_LOCK  4

/*
** File Locking Notes:  (Mostly about windows but also some info for Unix)
**
** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because
** those functions are not available.  So we use only LockFile() and
** UnlockFile().
**
** LockFile() prevents not just writing but also reading by other processes.
** A SHARED_LOCK is obtained by locking a single randomly-chosen
** byte out of a specific range of bytes. The lock byte is obtained at
** random so two separate readers can probably access the file at the
** same time, unless they are unlucky and choose the same lock byte.
** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range.
** There can only be one writer.  A RESERVED_LOCK is obtained by locking
** a single byte of the file that is designated as the reserved lock byte.
** A PENDING_LOCK is obtained by locking a designated byte different from
** the RESERVED_LOCK byte.
**
** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available,
** which means we can use reader/writer locks.  When reader/writer locks
** are used, the lock is placed on the same range of bytes that is used
** for probabilistic locking in Win95/98/ME.  Hence, the locking scheme
** will support two or more Win95 readers or two or more WinNT readers.
** But a single Win95 reader will lock out all WinNT readers and a single
** WinNT reader will lock out all other Win95 readers.
**
** The following #defines specify the range of bytes used for locking.
** SHARED_SIZE is the number of bytes available in the pool from which
** a random byte is selected for a shared lock.  The pool of bytes for
** shared locks begins at SHARED_FIRST.
**
** The same locking strategy and
** byte ranges are used for Unix.  This leaves open the possiblity of having
** clients on win95, winNT, and unix all talking to the same shared file
** and all locking correctly.  To do so would require that samba (or whatever
** tool is being used for file sharing) implements locks correctly between
** windows and unix.  I'm guessing that isn't likely to happen, but by
** using the same locking range we are at least open to the possibility.
**
** Locking in windows is manditory.  For this reason, we cannot store
** actual data in the bytes used for locking.  The pager never allocates
** the pages involved in locking therefore.  SHARED_SIZE is selected so
** that all locks will fit on a single page even at the minimum page size.
** PENDING_BYTE defines the beginning of the locks.  By default PENDING_BYTE
** is set high so that we don't have to allocate an unused page except
** for very large databases.  But one should test the page skipping logic
** by setting PENDING_BYTE low and running the entire regression suite.
**
** Changing the value of PENDING_BYTE results in a subtly incompatible
** file format.  Depending on how it is changed, you might not notice
** the incompatibility right away, even running a full regression test.
** The default location of PENDING_BYTE is the first byte past the
** 1GB boundary.
**
*/
#define PENDING_BYTE      sqlite3PendingByte
#define RESERVED_BYTE     (PENDING_BYTE+1)
#define SHARED_FIRST      (PENDING_BYTE+2)
#define SHARED_SIZE       510

/*
** Wrapper around OS specific sqlite3_os_init() function.
*/
SQLITE_PRIVATE int sqlite3OsInit(void);

/*
** Functions for accessing sqlite3_file methods
*/
SQLITE_PRIVATE int sqlite3OsClose(sqlite3_file*);
SQLITE_PRIVATE int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset);
SQLITE_PRIVATE int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset);
SQLITE_PRIVATE int sqlite3OsTruncate(sqlite3_file*, i64 size);
SQLITE_PRIVATE int sqlite3OsSync(sqlite3_file*, int);
SQLITE_PRIVATE int sqlite3OsFileSize(sqlite3_file*, i64 *pSize);
SQLITE_PRIVATE int sqlite3OsLock(sqlite3_file*, int);
SQLITE_PRIVATE int sqlite3OsUnlock(sqlite3_file*, int);
SQLITE_PRIVATE int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut);
SQLITE_PRIVATE int sqlite3OsFileControl(sqlite3_file*,int,void*);
#define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0
SQLITE_PRIVATE int sqlite3OsSectorSize(sqlite3_file *id);
SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id);

/*
** Functions for accessing sqlite3_vfs methods
*/
SQLITE_PRIVATE int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *);
SQLITE_PRIVATE int sqlite3OsDelete(sqlite3_vfs *, const char *, int);
SQLITE_PRIVATE int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut);
SQLITE_PRIVATE int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *);
#ifndef SQLITE_OMIT_LOAD_EXTENSION
SQLITE_PRIVATE void *sqlite3OsDlOpen(sqlite3_vfs *, const char *);
SQLITE_PRIVATE void sqlite3OsDlError(sqlite3_vfs *, int, char *);
SQLITE_PRIVATE void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void);
SQLITE_PRIVATE void sqlite3OsDlClose(sqlite3_vfs *, void *);
#endif /* SQLITE_OMIT_LOAD_EXTENSION */
SQLITE_PRIVATE int sqlite3OsRandomness(sqlite3_vfs *, int, char *);
SQLITE_PRIVATE int sqlite3OsSleep(sqlite3_vfs *, int);
SQLITE_PRIVATE int sqlite3OsCurrentTime(sqlite3_vfs *, double*);

/*
** Convenience functions for opening and closing files using
** sqlite3_malloc() to obtain space for the file-handle structure.
*/
SQLITE_PRIVATE int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*);
SQLITE_PRIVATE int sqlite3OsCloseFree(sqlite3_file *);

#endif /* _SQLITE_OS_H_ */

/************** End of os.h **************************************************/
/************** Continuing where we left off in sqliteInt.h ******************/
/************** Include mutex.h in the middle of sqliteInt.h *****************/
/************** Begin file mutex.h *******************************************/
/*
** 2007 August 28
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains the common header for all mutex implementations.
** The sqliteInt.h header #includes this file so that it is available
** to all source files.  We break it out in an effort to keep the code
** better organized.
**
** NOTE:  source files should *not* #include this header file directly.
** Source files should #include the sqliteInt.h file and let that file
** include this one indirectly.
*/


/*
** Figure out what version of the code to use.  The choices are
**
**   SQLITE_MUTEX_OMIT         No mutex logic.  Not even stubs.  The
**                             mutexes implemention cannot be overridden
**                             at start-time.
**
**   SQLITE_MUTEX_NOOP         For single-threaded applications.  No
**                             mutual exclusion is provided.  But this
**                             implementation can be overridden at
**                             start-time.
**
**   SQLITE_MUTEX_PTHREADS     For multi-threaded applications on Unix.
**
**   SQLITE_MUTEX_W32          For multi-threaded applications on Win32.
**
**   SQLITE_MUTEX_OS2          For multi-threaded applications on OS/2.
*/
#if !SQLITE_THREADSAFE
# define SQLITE_MUTEX_OMIT
#endif
#if SQLITE_THREADSAFE && !defined(SQLITE_MUTEX_NOOP)
#  if SQLITE_OS_UNIX
#    define SQLITE_MUTEX_PTHREADS
#  elif SQLITE_OS_WIN
#    define SQLITE_MUTEX_W32
#  elif SQLITE_OS_OS2
#    define SQLITE_MUTEX_OS2
#  else
#    define SQLITE_MUTEX_NOOP
#  endif
#endif

#ifdef SQLITE_MUTEX_OMIT
/*
** If this is a no-op implementation, implement everything as macros.
*/
#define sqlite3_mutex_alloc(X)    ((sqlite3_mutex*)8)
#define sqlite3_mutex_free(X)
#define sqlite3_mutex_enter(X)
#define sqlite3_mutex_try(X)      SQLITE_OK
#define sqlite3_mutex_leave(X)
#define sqlite3_mutex_held(X)     1
#define sqlite3_mutex_notheld(X)  1
#define sqlite3MutexAlloc(X)      ((sqlite3_mutex*)8)
#define sqlite3MutexInit()        SQLITE_OK
#define sqlite3MutexEnd()
#endif /* defined(SQLITE_MUTEX_OMIT) */

/************** End of mutex.h ***********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/


/*
** Each database file to be accessed by the system is an instance
** of the following structure.  There are normally two of these structures
** in the sqlite.aDb[] array.  aDb[0] is the main database file and
** aDb[1] is the database file used to hold temporary tables.  Additional
** databases may be attached.
*/
struct Db {
  char *zName;         /* Name of this database */
  Btree *pBt;          /* The B*Tree structure for this database file */
  u8 inTrans;          /* 0: not writable.  1: Transaction.  2: Checkpoint */
  u8 safety_level;     /* How aggressive at syncing data to disk */
  Schema *pSchema;     /* Pointer to database schema (possibly shared) */
};

/*
** An instance of the following structure stores a database schema.
**
** If there are no virtual tables configured in this schema, the
** Schema.db variable is set to NULL. After the first virtual table
** has been added, it is set to point to the database connection
** used to create the connection. Once a virtual table has been
** added to the Schema structure and the Schema.db variable populated,
** only that database connection may use the Schema to prepare
** statements.
*/
struct Schema {
  int schema_cookie;   /* Database schema version number for this file */
  Hash tblHash;        /* All tables indexed by name */
  Hash idxHash;        /* All (named) indices indexed by name */
  Hash trigHash;       /* All triggers indexed by name */
  Hash fkeyHash;       /* All foreign keys by referenced table name */
  Table *pSeqTab;      /* The sqlite_sequence table used by AUTOINCREMENT */
  u8 file_format;      /* Schema format version for this file */
  u8 enc;              /* Text encoding used by this database */
  u16 flags;           /* Flags associated with this schema */
  int cache_size;      /* Number of pages to use in the cache */
#ifndef SQLITE_OMIT_VIRTUALTABLE
  sqlite3 *db;         /* "Owner" connection. See comment above */
#endif
};

/*
** These macros can be used to test, set, or clear bits in the
** Db.flags field.
*/
#define DbHasProperty(D,I,P)     (((D)->aDb[I].pSchema->flags&(P))==(P))
#define DbHasAnyProperty(D,I,P)  (((D)->aDb[I].pSchema->flags&(P))!=0)
#define DbSetProperty(D,I,P)     (D)->aDb[I].pSchema->flags|=(P)
#define DbClearProperty(D,I,P)   (D)->aDb[I].pSchema->flags&=~(P)

/*
** Allowed values for the DB.flags field.
**
** The DB_SchemaLoaded flag is set after the database schema has been
** read into internal hash tables.
**
** DB_UnresetViews means that one or more views have column names that
** have been filled out.  If the schema changes, these column names might
** changes and so the view will need to be reset.
*/
#define DB_SchemaLoaded    0x0001  /* The schema has been loaded */
#define DB_UnresetViews    0x0002  /* Some views have defined column names */
#define DB_Empty           0x0004  /* The file is empty (length 0 bytes) */

/*
** The number of different kinds of things that can be limited
** using the sqlite3_limit() interface.
*/
#define SQLITE_N_LIMIT (SQLITE_LIMIT_TRIGGER_DEPTH+1)

/*
** Lookaside malloc is a set of fixed-size buffers that can be used
** to satisfy small transient memory allocation requests for objects
** associated with a particular database connection.  The use of
** lookaside malloc provides a significant performance enhancement
** (approx 10%) by avoiding numerous malloc/free requests while parsing
** SQL statements.
**
** The Lookaside structure holds configuration information about the
** lookaside malloc subsystem.  Each available memory allocation in
** the lookaside subsystem is stored on a linked list of LookasideSlot
** objects.
**
** Lookaside allocations are only allowed for objects that are associated
** with a particular database connection.  Hence, schema information cannot
** be stored in lookaside because in shared cache mode the schema information
** is shared by multiple database connections.  Therefore, while parsing
** schema information, the Lookaside.bEnabled flag is cleared so that
** lookaside allocations are not used to construct the schema objects.
*/
struct Lookaside {
  u16 sz;                 /* Size of each buffer in bytes */
  u8 bEnabled;            /* False to disable new lookaside allocations */
  u8 bMalloced;           /* True if pStart obtained from sqlite3_malloc() */
  int nOut;               /* Number of buffers currently checked out */
  int mxOut;              /* Highwater mark for nOut */
  LookasideSlot *pFree;   /* List of available buffers */
  void *pStart;           /* First byte of available memory space */
  void *pEnd;             /* First byte past end of available space */
};
struct LookasideSlot {
  LookasideSlot *pNext;    /* Next buffer in the list of free buffers */
};

/*
** A hash table for function definitions.
**
** Hash each FuncDef structure into one of the FuncDefHash.a[] slots.
** Collisions are on the FuncDef.pHash chain.
*/
struct FuncDefHash {
  FuncDef *a[23];       /* Hash table for functions */
};

/*
** Each database is an instance of the following structure.
**
** The sqlite.lastRowid records the last insert rowid generated by an
** insert statement.  Inserts on views do not affect its value.  Each
** trigger has its own context, so that lastRowid can be updated inside
** triggers as usual.  The previous value will be restored once the trigger
** exits.  Upon entering a before or instead of trigger, lastRowid is no
** longer (since after version 2.8.12) reset to -1.
**
** The sqlite.nChange does not count changes within triggers and keeps no
** context.  It is reset at start of sqlite3_exec.
** The sqlite.lsChange represents the number of changes made by the last
** insert, update, or delete statement.  It remains constant throughout the
** length of a statement and is then updated by OP_SetCounts.  It keeps a
** context stack just like lastRowid so that the count of changes
** within a trigger is not seen outside the trigger.  Changes to views do not
** affect the value of lsChange.
** The sqlite.csChange keeps track of the number of current changes (since
** the last statement) and is used to update sqlite_lsChange.
**
** The member variables sqlite.errCode, sqlite.zErrMsg and sqlite.zErrMsg16
** store the most recent error code and, if applicable, string. The
** internal function sqlite3Error() is used to set these variables
** consistently.
*/
struct sqlite3 {
  sqlite3_vfs *pVfs;            /* OS Interface */
  int nDb;                      /* Number of backends currently in use */
  Db *aDb;                      /* All backends */
  int flags;                    /* Miscellaneous flags. See below */
  int openFlags;                /* Flags passed to sqlite3_vfs.xOpen() */
  int errCode;                  /* Most recent error code (SQLITE_*) */
  int errMask;                  /* & result codes with this before returning */
  u8 autoCommit;                /* The auto-commit flag. */
  u8 temp_store;                /* 1: file 2: memory 0: default */
  u8 mallocFailed;              /* True if we have seen a malloc failure */
  u8 dfltLockMode;              /* Default locking-mode for attached dbs */
  u8 dfltJournalMode;           /* Default journal mode for attached dbs */
  signed char nextAutovac;      /* Autovac setting after VACUUM if >=0 */
  u8 suppressErr;               /* Do not issue error messages if true */
  int nextPagesize;             /* Pagesize after VACUUM if >0 */
  int nTable;                   /* Number of tables in the database */
  CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  u32 magic;                    /* Magic number for detect library misuse */
  int nChange;                  /* Value returned by sqlite3_changes() */
  int nTotalChange;             /* Value returned by sqlite3_total_changes() */
  sqlite3_mutex *mutex;         /* Connection mutex */
  int aLimit[SQLITE_N_LIMIT];   /* Limits */
  struct sqlite3InitInfo {      /* Information used during initialization */
    int iDb;                    /* When back is being initialized */
    int newTnum;                /* Rootpage of table being initialized */
    u8 busy;                    /* TRUE if currently initializing */
    u8 orphanTrigger;           /* Last statement is orphaned TEMP trigger */
  } init;
  int nExtension;               /* Number of loaded extensions */
  void **aExtension;            /* Array of shared library handles */
  struct Vdbe *pVdbe;           /* List of active virtual machines */
  int activeVdbeCnt;            /* Number of VDBEs currently executing */
  int writeVdbeCnt;             /* Number of active VDBEs that are writing */
  void (*xTrace)(void*,const char*);        /* Trace function */
  void *pTraceArg;                          /* Argument to the trace function */
  void (*xProfile)(void*,const char*,u64);  /* Profiling function */
  void *pProfileArg;                        /* Argument to profile function */
  void *pCommitArg;                 /* Argument to xCommitCallback() */
  int (*xCommitCallback)(void*);    /* Invoked at every commit. */
  void *pRollbackArg;               /* Argument to xRollbackCallback() */
  void (*xRollbackCallback)(void*); /* Invoked at every commit. */
  void *pUpdateArg;
  void (*xUpdateCallback)(void*,int, const char*,const char*,sqlite_int64);
  void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*);
  void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*);
  void *pCollNeededArg;
  sqlite3_value *pErr;          /* Most recent error message */
  char *zErrMsg;                /* Most recent error message (UTF-8 encoded) */
  char *zErrMsg16;              /* Most recent error message (UTF-16 encoded) */
  union {
    volatile int isInterrupted; /* True if sqlite3_interrupt has been called */
    double notUsed1;            /* Spacer */
  } u1;
  Lookaside lookaside;          /* Lookaside malloc configuration */
#ifndef SQLITE_OMIT_AUTHORIZATION
  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*);
                                /* Access authorization function */
  void *pAuthArg;               /* 1st argument to the access auth function */
#endif
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  int (*xProgress)(void *);     /* The progress callback */
  void *pProgressArg;           /* Argument to the progress callback */
  int nProgressOps;             /* Number of opcodes for progress callback */
#endif
#ifndef SQLITE_OMIT_VIRTUALTABLE
  Hash aModule;                 /* populated by sqlite3_create_module() */
  Table *pVTab;                 /* vtab with active Connect/Create method */
  VTable **aVTrans;             /* Virtual tables with open transactions */
  int nVTrans;                  /* Allocated size of aVTrans */
  VTable *pDisconnect;    /* Disconnect these in next sqlite3_prepare() */
#endif
  FuncDefHash aFunc;            /* Hash table of connection functions */
  Hash aCollSeq;                /* All collating sequences */
  BusyHandler busyHandler;      /* Busy callback */
  int busyTimeout;              /* Busy handler timeout, in msec */
  Db aDbStatic[2];              /* Static space for the 2 default backends */
  Savepoint *pSavepoint;        /* List of active savepoints */
  int nSavepoint;               /* Number of non-transaction savepoints */
  int nStatement;               /* Number of nested statement-transactions  */
  u8 isTransactionSavepoint;    /* True if the outermost savepoint is a TS */
  i64 nDeferredCons;            /* Net deferred constraints this transaction. */

#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
  /* The following variables are all protected by the STATIC_MASTER
  ** mutex, not by sqlite3.mutex. They are used by code in notify.c.
  **
  ** When X.pUnlockConnection==Y, that means that X is waiting for Y to
  ** unlock so that it can proceed.
  **
  ** When X.pBlockingConnection==Y, that means that something that X tried
  ** tried to do recently failed with an SQLITE_LOCKED error due to locks
  ** held by Y.
  */
  sqlite3 *pBlockingConnection; /* Connection that caused SQLITE_LOCKED */
  sqlite3 *pUnlockConnection;           /* Connection to watch for unlock */
  void *pUnlockArg;                     /* Argument to xUnlockNotify */
  void (*xUnlockNotify)(void **, int);  /* Unlock notify callback */
  sqlite3 *pNextBlocked;        /* Next in list of all blocked connections */
#endif
};

/*
** A macro to discover the encoding of a database.
*/
#define ENC(db) ((db)->aDb[0].pSchema->enc)

/*
** Possible values for the sqlite3.flags.
*/
#define SQLITE_VdbeTrace      0x00000100  /* True to trace VDBE execution */
#define SQLITE_InternChanges  0x00000200  /* Uncommitted Hash table changes */
#define SQLITE_FullColNames   0x00000400  /* Show full column names on SELECT */
#define SQLITE_ShortColNames  0x00000800  /* Show short columns names */
#define SQLITE_CountRows      0x00001000  /* Count rows changed by INSERT, */
                                          /*   DELETE, or UPDATE and return */
                                          /*   the count using a callback. */
#define SQLITE_NullCallback   0x00002000  /* Invoke the callback once if the */
                                          /*   result set is empty */
#define SQLITE_SqlTrace       0x00004000  /* Debug print SQL as it executes */
#define SQLITE_VdbeListing    0x00008000  /* Debug listings of VDBE programs */
#define SQLITE_WriteSchema    0x00010000  /* OK to update SQLITE_MASTER */
#define SQLITE_NoReadlock     0x00020000  /* Readlocks are omitted when
                                          ** accessing read-only databases */
#define SQLITE_IgnoreChecks   0x00040000  /* Do not enforce check constraints */
#define SQLITE_ReadUncommitted 0x0080000  /* For shared-cache mode */
#define SQLITE_LegacyFileFmt  0x00100000  /* Create new databases in format 1 */
#define SQLITE_FullFSync      0x00200000  /* Use full fsync on the backend */
#define SQLITE_LoadExtension  0x00400000  /* Enable load_extension */
#define SQLITE_RecoveryMode   0x00800000  /* Ignore schema errors */
#define SQLITE_ReverseOrder   0x01000000  /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers    0x02000000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x04000000  /* Enforce foreign key constraints  */

/*
** Bits of the sqlite3.flags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface.
** These must be the low-order bits of the flags field.
*/
#define SQLITE_QueryFlattener 0x01        /* Disable query flattening */
#define SQLITE_ColumnCache    0x02        /* Disable the column cache */
#define SQLITE_IndexSort      0x04        /* Disable indexes for sorting */
#define SQLITE_IndexSearch    0x08        /* Disable indexes for searching */
#define SQLITE_IndexCover     0x10        /* Disable index covering table */
#define SQLITE_OptMask        0x1f        /* Mask of all disablable opts */

/*
** Possible values for the sqlite.magic field.
** The numbers are obtained at random and have no special meaning, other
** than being distinct from one another.
*/
#define SQLITE_MAGIC_OPEN     0xa029a697  /* Database is open */
#define SQLITE_MAGIC_CLOSED   0x9f3c2d33  /* Database is closed */
#define SQLITE_MAGIC_SICK     0x4b771290  /* Error and awaiting close */
#define SQLITE_MAGIC_BUSY     0xf03b7906  /* Database currently in use */
#define SQLITE_MAGIC_ERROR    0xb5357930  /* An SQLITE_MISUSE error occurred */

/*
** Each SQL function is defined by an instance of the following
** structure.  A pointer to this structure is stored in the sqlite.aFunc
** hash table.  When multiple functions have the same name, the hash table
** points to a linked list of these structures.
*/
struct FuncDef {
  i16 nArg;            /* Number of arguments.  -1 means unlimited */
  u8 iPrefEnc;         /* Preferred text encoding (SQLITE_UTF8, 16LE, 16BE) */
  u8 flags;            /* Some combination of SQLITE_FUNC_* */
  void *pUserData;     /* User data parameter */
  FuncDef *pNext;      /* Next function with same name */
  void (*xFunc)(sqlite3_context*,int,sqlite3_value**); /* Regular function */
  void (*xStep)(sqlite3_context*,int,sqlite3_value**); /* Aggregate step */
  void (*xFinalize)(sqlite3_context*);                /* Aggregate finalizer */
  char *zName;         /* SQL name of the function. */
  FuncDef *pHash;      /* Next with a different name but the same hash */
};

/*
** Possible values for FuncDef.flags
*/
#define SQLITE_FUNC_LIKE     0x01 /* Candidate for the LIKE optimization */
#define SQLITE_FUNC_CASE     0x02 /* Case-sensitive LIKE-type function */
#define SQLITE_FUNC_EPHEM    0x04 /* Ephemeral.  Delete with VDBE */
#define SQLITE_FUNC_NEEDCOLL 0x08 /* sqlite3GetFuncCollSeq() might be called */
#define SQLITE_FUNC_PRIVATE  0x10 /* Allowed for internal use only */
#define SQLITE_FUNC_COUNT    0x20 /* Built-in count(*) aggregate */
#define SQLITE_FUNC_COALESCE 0x40 /* Built-in coalesce() or ifnull() function */

/*
** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
** used to create the initializers for the FuncDef structures.
**
**   FUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Used to create a scalar function definition of a function zName
**     implemented by C function xFunc that accepts nArg arguments. The
**     value passed as iArg is cast to a (void*) and made available
**     as the user-data (sqlite3_user_data()) for the function. If
**     argument bNC is true, then the SQLITE_FUNC_NEEDCOLL flag is set.
**
**   AGGREGATE(zName, nArg, iArg, bNC, xStep, xFinal)
**     Used to create an aggregate function definition implemented by
**     the C functions xStep and xFinal. The first four parameters
**     are interpreted in the same way as the first 4 parameters to
**     FUNCTION().
**
**   LIKEFUNC(zName, nArg, pArg, flags)
**     Used to create a scalar function definition of a function zName
**     that accepts nArg arguments and is implemented by a call to C
**     function likeFunc. Argument pArg is cast to a (void *) and made
**     available as the function user-data (sqlite3_user_data()). The
**     FuncDef.flags variable is set to the value passed as the flags
**     parameter.
*/
#define FUNCTION(zName, nArg, iArg, bNC, xFunc) \
  {nArg, SQLITE_UTF8, bNC*SQLITE_FUNC_NEEDCOLL, \
   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0}
#define STR_FUNCTION(zName, nArg, pArg, bNC, xFunc) \
  {nArg, SQLITE_UTF8, bNC*SQLITE_FUNC_NEEDCOLL, \
   pArg, 0, xFunc, 0, 0, #zName, 0}
#define LIKEFUNC(zName, nArg, arg, flags) \
  {nArg, SQLITE_UTF8, flags, (void *)arg, 0, likeFunc, 0, 0, #zName, 0}
#define AGGREGATE(zName, nArg, arg, nc, xStep, xFinal) \
  {nArg, SQLITE_UTF8, nc*SQLITE_FUNC_NEEDCOLL, \
   SQLITE_INT_TO_PTR(arg), 0, 0, xStep,xFinal,#zName,0}

/*
** All current savepoints are stored in a linked list starting at
** sqlite3.pSavepoint. The first element in the list is the most recently
** opened savepoint. Savepoints are added to the list by the vdbe
** OP_Savepoint instruction.
*/
struct Savepoint {
  char *zName;                        /* Savepoint name (nul-terminated) */
  i64 nDeferredCons;                  /* Number of deferred fk violations */
  Savepoint *pNext;                   /* Parent savepoint (if any) */
};

/*
** The following are used as the second parameter to sqlite3Savepoint(),
** and as the P1 argument to the OP_Savepoint instruction.
*/
#define SAVEPOINT_BEGIN      0
#define SAVEPOINT_RELEASE    1
#define SAVEPOINT_ROLLBACK   2


/*
** Each SQLite module (virtual table definition) is defined by an
** instance of the following structure, stored in the sqlite3.aModule
** hash table.
*/
struct Module {
  const sqlite3_module *pModule;       /* Callback pointers */
  const char *zName;                   /* Name passed to create_module() */
  void *pAux;                          /* pAux passed to create_module() */
  void (*xDestroy)(void *);            /* Module destructor function */
};

/*
** information about each column of an SQL table is held in an instance
** of this structure.
*/
struct Column {
  char *zName;     /* Name of this column */
  Expr *pDflt;     /* Default value of this column */
  char *zDflt;     /* Original text of the default value */
  char *zType;     /* Data type for this column */
  char *zColl;     /* Collating sequence.  If NULL, use the default */
  u8 notNull;      /* True if there is a NOT NULL constraint */
  u8 isPrimKey;    /* True if this column is part of the PRIMARY KEY */
  char affinity;   /* One of the SQLITE_AFF_... values */
#ifndef SQLITE_OMIT_VIRTUALTABLE
  u8 isHidden;     /* True if this column is 'hidden' */
#endif
};

/*
** A "Collating Sequence" is defined by an instance of the following
** structure. Conceptually, a collating sequence consists of a name and
** a comparison routine that defines the order of that sequence.
**
** There may two separate implementations of the collation function, one
** that processes text in UTF-8 encoding (CollSeq.xCmp) and another that
** processes text encoded in UTF-16 (CollSeq.xCmp16), using the machine
** native byte order. When a collation sequence is invoked, SQLite selects
** the version that will require the least expensive encoding
** translations, if any.
**
** The CollSeq.pUser member variable is an extra parameter that passed in
** as the first argument to the UTF-8 comparison function, xCmp.
** CollSeq.pUser16 is the equivalent for the UTF-16 comparison function,
** xCmp16.
**
** If both CollSeq.xCmp and CollSeq.xCmp16 are NULL, it means that the
** collating sequence is undefined.  Indices built on an undefined
** collating sequence may not be read or written.
*/
struct CollSeq {
  char *zName;          /* Name of the collating sequence, UTF-8 encoded */
  u8 enc;               /* Text encoding handled by xCmp() */
  u8 type;              /* One of the SQLITE_COLL_... values below */
  void *pUser;          /* First argument to xCmp() */
  int (*xCmp)(void*,int, const void*, int, const void*);
  void (*xDel)(void*);  /* Destructor for pUser */
};

/*
** Allowed values of CollSeq.type:
*/
#define SQLITE_COLL_BINARY  1  /* The default memcmp() collating sequence */
#define SQLITE_COLL_NOCASE  2  /* The built-in NOCASE collating sequence */
#define SQLITE_COLL_REVERSE 3  /* The built-in REVERSE collating sequence */
#define SQLITE_COLL_USER    0  /* Any other user-defined collating sequence */

/*
** A sort order can be either ASC or DESC.
*/
#define SQLITE_SO_ASC       0  /* Sort in ascending order */
#define SQLITE_SO_DESC      1  /* Sort in ascending order */

/*
** Column affinity types.
**
** These used to have mnemonic name like 'i' for SQLITE_AFF_INTEGER and
** 't' for SQLITE_AFF_TEXT.  But we can save a little space and improve
** the speed a little by numbering the values consecutively.
**
** But rather than start with 0 or 1, we begin with 'a'.  That way,
** when multiple affinity types are concatenated into a string and
** used as the P4 operand, they will be more readable.
**
** Note also that the numeric types are grouped together so that testing
** for a numeric type is a single comparison.
*/
#define SQLITE_AFF_TEXT     'a'
#define SQLITE_AFF_NONE     'b'
#define SQLITE_AFF_NUMERIC  'c'
#define SQLITE_AFF_INTEGER  'd'
#define SQLITE_AFF_REAL     'e'

#define sqlite3IsNumericAffinity(X)  ((X)>=SQLITE_AFF_NUMERIC)

/*
** The SQLITE_AFF_MASK values masks off the significant bits of an
** affinity value.
*/
#define SQLITE_AFF_MASK     0x67

/*
** Additional bit values that can be ORed with an affinity without
** changing the affinity.
*/
#define SQLITE_JUMPIFNULL   0x08  /* jumps if either operand is NULL */
#define SQLITE_STOREP2      0x10  /* Store result in reg[P2] rather than jump */
#define SQLITE_NULLEQ       0x80  /* NULL=NULL */

/*
** An object of this type is created for each virtual table present in
** the database schema.
**
** If the database schema is shared, then there is one instance of this
** structure for each database connection (sqlite3*) that uses the shared
** schema. This is because each database connection requires its own unique
** instance of the sqlite3_vtab* handle used to access the virtual table
** implementation. sqlite3_vtab* handles can not be shared between
** database connections, even when the rest of the in-memory database
** schema is shared, as the implementation often stores the database
** connection handle passed to it via the xConnect() or xCreate() method
** during initialization internally. This database connection handle may
** then used by the virtual table implementation to access real tables
** within the database. So that they appear as part of the callers
** transaction, these accesses need to be made via the same database
** connection as that used to execute SQL operations on the virtual table.
**
** All VTable objects that correspond to a single table in a shared
** database schema are initially stored in a linked-list pointed to by
** the Table.pVTable member variable of the corresponding Table object.
** When an sqlite3_prepare() operation is required to access the virtual
** table, it searches the list for the VTable that corresponds to the
** database connection doing the preparing so as to use the correct
** sqlite3_vtab* handle in the compiled query.
**
** When an in-memory Table object is deleted (for example when the
** schema is being reloaded for some reason), the VTable objects are not
** deleted and the sqlite3_vtab* handles are not xDisconnect()ed
** immediately. Instead, they are moved from the Table.pVTable list to
** another linked list headed by the sqlite3.pDisconnect member of the
** corresponding sqlite3 structure. They are then deleted/xDisconnected
** next time a statement is prepared using said sqlite3*. This is done
** to avoid deadlock issues involving multiple sqlite3.mutex mutexes.
** Refer to comments above function sqlite3VtabUnlockList() for an
** explanation as to why it is safe to add an entry to an sqlite3.pDisconnect
** list without holding the corresponding sqlite3.mutex mutex.
**
** The memory for objects of this type is always allocated by
** sqlite3DbMalloc(), using the connection handle stored in VTable.db as
** the first argument.
*/
struct VTable {
  sqlite3 *db;              /* Database connection associated with this table */
  Module *pMod;             /* Pointer to module implementation */
  sqlite3_vtab *pVtab;      /* Pointer to vtab instance */
  int nRef;                 /* Number of pointers to this structure */
  VTable *pNext;            /* Next in linked list (see above) */
};

/*
** Each SQL table is represented in memory by an instance of the
** following structure.
**
** Table.zName is the name of the table.  The case of the original
** CREATE TABLE statement is stored, but case is not significant for
** comparisons.
**
** Table.nCol is the number of columns in this table.  Table.aCol is a
** pointer to an array of Column structures, one for each column.
**
** If the table has an INTEGER PRIMARY KEY, then Table.iPKey is the index of
** the column that is that key.   Otherwise Table.iPKey is negative.  Note
** that the datatype of the PRIMARY KEY must be INTEGER for this field to
** be set.  An INTEGER PRIMARY KEY is used as the rowid for each row of
** the table.  If a table has no INTEGER PRIMARY KEY, then a random rowid
** is generated for each row of the table.  TF_HasPrimaryKey is set if
** the table has any PRIMARY KEY, INTEGER or otherwise.
**
** Table.tnum is the page number for the root BTree page of the table in the
** database file.  If Table.iDb is the index of the database table backend
** in sqlite.aDb[].  0 is for the main database and 1 is for the file that
** holds temporary tables and indices.  If TF_Ephemeral is set
** then the table is stored in a file that is automatically deleted
** when the VDBE cursor to the table is closed.  In this case Table.tnum
** refers VDBE cursor number that holds the table open, not to the root
** page number.  Transient tables are used to hold the results of a
** sub-query that appears instead of a real table name in the FROM clause
** of a SELECT statement.
*/
struct Table {
  sqlite3 *dbMem;      /* DB connection used for lookaside allocations. */
  char *zName;         /* Name of the table or view */
  int iPKey;           /* If not negative, use aCol[iPKey] as the primary key */
  int nCol;            /* Number of columns in this table */
  Column *aCol;        /* Information about each column */
  Index *pIndex;       /* List of SQL indexes on this table. */
  int tnum;            /* Root BTree node for this table (see note above) */
  Select *pSelect;     /* NULL for tables.  Points to definition if a view. */
  u16 nRef;            /* Number of pointers to this Table */
  u8 tabFlags;         /* Mask of TF_* values */
  u8 keyConf;          /* What to do in case of uniqueness conflict on iPKey */
  FKey *pFKey;         /* Linked list of all foreign keys in this table */
  char *zColAff;       /* String defining the affinity of each column */
#ifndef SQLITE_OMIT_CHECK
  Expr *pCheck;        /* The AND of all CHECK constraints */
#endif
#ifndef SQLITE_OMIT_ALTERTABLE
  int addColOffset;    /* Offset in CREATE TABLE stmt to add a new column */
#endif
#ifndef SQLITE_OMIT_VIRTUALTABLE
  VTable *pVTable;     /* List of VTable objects. */
  int nModuleArg;      /* Number of arguments to the module */
  char **azModuleArg;  /* Text of all module args. [0] is module name */
#endif
  Trigger *pTrigger;   /* List of triggers stored in pSchema */
  Schema *pSchema;     /* Schema that contains this table */
  Table *pNextZombie;  /* Next on the Parse.pZombieTab list */
};

/*
** Allowed values for Tabe.tabFlags.
*/
#define TF_Readonly        0x01    /* Read-only system table */
#define TF_Ephemeral       0x02    /* An ephemeral table */
#define TF_HasPrimaryKey   0x04    /* Table has a primary key */
#define TF_Autoincrement   0x08    /* Integer primary key is autoincrement */
#define TF_Virtual         0x10    /* Is a virtual table */
#define TF_NeedMetadata    0x20    /* aCol[].zType and aCol[].pColl missing */



/*
** Test to see whether or not a table is a virtual table.  This is
** done as a macro so that it will be optimized out when virtual
** table support is omitted from the build.
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE
#  define IsVirtual(X)      (((X)->tabFlags & TF_Virtual)!=0)
#  define IsHiddenColumn(X) ((X)->isHidden)
#else
#  define IsVirtual(X)      0
#  define IsHiddenColumn(X) 0
#endif

/*
** Each foreign key constraint is an instance of the following structure.
**
** A foreign key is associated with two tables.  The "from" table is
** the table that contains the REFERENCES clause that creates the foreign
** key.  The "to" table is the table that is named in the REFERENCES clause.
** Consider this example:
**
**     CREATE TABLE ex1(
**       a INTEGER PRIMARY KEY,
**       b INTEGER CONSTRAINT fk1 REFERENCES ex2(x)
**     );
**
** For foreign key "fk1", the from-table is "ex1" and the to-table is "ex2".
**
** Each REFERENCES clause generates an instance of the following structure
** which is attached to the from-table.  The to-table need not exist when
** the from-table is created.  The existence of the to-table is not checked.
*/
struct FKey {
  Table *pFrom;     /* Table containing the REFERENCES clause (aka: Child) */
  FKey *pNextFrom;  /* Next foreign key in pFrom */
  char *zTo;        /* Name of table that the key points to (aka: Parent) */
  FKey *pNextTo;    /* Next foreign key on table named zTo */
  FKey *pPrevTo;    /* Previous foreign key on table named zTo */
  int nCol;         /* Number of columns in this key */
  /* EV: R-30323-21917 */
  u8 isDeferred;    /* True if constraint checking is deferred till COMMIT */
  u8 aAction[2];          /* ON DELETE and ON UPDATE actions, respectively */
  Trigger *apTrigger[2];  /* Triggers for aAction[] actions */
  struct sColMap {  /* Mapping of columns in pFrom to columns in zTo */
    int iFrom;         /* Index of column in pFrom */
    char *zCol;        /* Name of column in zTo.  If 0 use PRIMARY KEY */
  } aCol[1];        /* One entry for each of nCol column s */
};

/*
** SQLite supports many different ways to resolve a constraint
** error.  ROLLBACK processing means that a constraint violation
** causes the operation in process to fail and for the current transaction
** to be rolled back.  ABORT processing means the operation in process
** fails and any prior changes from that one operation are backed out,
** but the transaction is not rolled back.  FAIL processing means that
** the operation in progress stops and returns an error code.  But prior
** changes due to the same operation are not backed out and no rollback
** occurs.  IGNORE means that the particular row that caused the constraint
** error is not inserted or updated.  Processing continues and no error
** is returned.  REPLACE means that preexisting database rows that caused
** a UNIQUE constraint violation are removed so that the new insert or
** update can proceed.  Processing continues and no error is reported.
**
** RESTRICT, SETNULL, and CASCADE actions apply only to foreign keys.
** RESTRICT is the same as ABORT for IMMEDIATE foreign keys and the
** same as ROLLBACK for DEFERRED keys.  SETNULL means that the foreign
** key is set to NULL.  CASCADE means that a DELETE or UPDATE of the
** referenced table row is propagated into the row that holds the
** foreign key.
**
** The following symbolic values are used to record which type
** of action to take.
*/
#define OE_None     0   /* There is no constraint to check */
#define OE_Rollback 1   /* Fail the operation and rollback the transaction */
#define OE_Abort    2   /* Back out changes but do no rollback transaction */
#define OE_Fail     3   /* Stop the operation but leave all prior changes */
#define OE_Ignore   4   /* Ignore the error. Do not do the INSERT or UPDATE */
#define OE_Replace  5   /* Delete existing record, then do INSERT or UPDATE */

#define OE_Restrict 6   /* OE_Abort for IMMEDIATE, OE_Rollback for DEFERRED */
#define OE_SetNull  7   /* Set the foreign key value to NULL */
#define OE_SetDflt  8   /* Set the foreign key value to its default */
#define OE_Cascade  9   /* Cascade the changes */

#define OE_Default  99  /* Do whatever the default action is */


/*
** An instance of the following structure is passed as the first
** argument to sqlite3VdbeKeyCompare and is used to control the
** comparison of the two index keys.
*/
struct KeyInfo {
  sqlite3 *db;        /* The database connection */
  u8 enc;             /* Text encoding - one of the TEXT_Utf* values */
  u16 nField;         /* Number of entries in aColl[] */
  u8 *aSortOrder;     /* If defined an aSortOrder[i] is true, sort DESC */
  CollSeq *aColl[1];  /* Collating sequence for each term of the key */
};

/*
** An instance of the following structure holds information about a
** single index record that has already been parsed out into individual
** values.
**
** A record is an object that contains one or more fields of data.
** Records are used to store the content of a table row and to store
** the key of an index.  A blob encoding of a record is created by
** the OP_MakeRecord opcode of the VDBE and is disassembled by the
** OP_Column opcode.
**
** This structure holds a record that has already been disassembled
** into its constituent fields.
*/
struct UnpackedRecord {
  KeyInfo *pKeyInfo;  /* Collation and sort-order information */
  u16 nField;         /* Number of entries in apMem[] */
  u16 flags;          /* Boolean settings.  UNPACKED_... below */
  i64 rowid;          /* Used by UNPACKED_PREFIX_SEARCH */
  Mem *aMem;          /* Values */
};

/*
** Allowed values of UnpackedRecord.flags
*/
#define UNPACKED_NEED_FREE     0x0001  /* Memory is from sqlite3Malloc() */
#define UNPACKED_NEED_DESTROY  0x0002  /* apMem[]s should all be destroyed */
#define UNPACKED_IGNORE_ROWID  0x0004  /* Ignore trailing rowid on key1 */
#define UNPACKED_INCRKEY       0x0008  /* Make this key an epsilon larger */
#define UNPACKED_PREFIX_MATCH  0x0010  /* A prefix match is considered OK */
#define UNPACKED_PREFIX_SEARCH 0x0020  /* A prefix match is considered OK */

/*
** Each SQL index is represented in memory by an
** instance of the following structure.
**
** The columns of the table that are to be indexed are described
** by the aiColumn[] field of this structure.  For example, suppose
** we have the following table and index:
**
**     CREATE TABLE Ex1(c1 int, c2 int, c3 text);
**     CREATE INDEX Ex2 ON Ex1(c3,c1);
**
** In the Table structure describing Ex1, nCol==3 because there are
** three columns in the table.  In the Index structure describing
** Ex2, nColumn==2 since 2 of the 3 columns of Ex1 are indexed.
** The value of aiColumn is {2, 0}.  aiColumn[0]==2 because the
** first column to be indexed (c3) has an index of 2 in Ex1.aCol[].
** The second column to be indexed (c1) has an index of 0 in
** Ex1.aCol[], hence Ex2.aiColumn[1]==0.
**
** The Index.onError field determines whether or not the indexed columns
** must be unique and what to do if they are not.  When Index.onError=OE_None,
** it means this is not a unique index.  Otherwise it is a unique index
** and the value of Index.onError indicate the which conflict resolution
** algorithm to employ whenever an attempt is made to insert a non-unique
** element.
*/
struct Index {
  char *zName;     /* Name of this index */
  int nColumn;     /* Number of columns in the table used by this index */
  int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
  unsigned *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
  Table *pTable;   /* The SQL table being indexed */
  int tnum;        /* Page containing root of this index in database file */
  u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
  u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */
  char *zColAff;   /* String defining the affinity of each column */
  Index *pNext;    /* The next index associated with the same table */
  Schema *pSchema; /* Schema containing this index */
  u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
  char **azColl;   /* Array of collation sequence names for index */
  IndexSample *aSample;    /* Array of SQLITE_INDEX_SAMPLES samples */
};

/*
** Each sample stored in the sqlite_stat2 table is represented in memory
** using a structure of this type.
*/
struct IndexSample {
  union {
    char *z;        /* Value if eType is SQLITE_TEXT or SQLITE_BLOB */
    double r;       /* Value if eType is SQLITE_FLOAT or SQLITE_INTEGER */
  } u;
  u8 eType;         /* SQLITE_NULL, SQLITE_INTEGER ... etc. */
  u8 nByte;         /* Size in byte of text or blob. */
};

/*
** Each token coming out of the lexer is an instance of
** this structure.  Tokens are also used as part of an expression.
**
** Note if Token.z==0 then Token.dyn and Token.n are undefined and
** may contain random values.  Do not make any assumptions about Token.dyn
** and Token.n when Token.z==0.
*/
struct Token {
  const char *z;     /* Text of the token.  Not NULL-terminated! */
  unsigned int n;    /* Number of characters in this token */
};

/*
** An instance of this structure contains information needed to generate
** code for a SELECT that contains aggregate functions.
**
** If Expr.op==TK_AGG_COLUMN or TK_AGG_FUNCTION then Expr.pAggInfo is a
** pointer to this structure.  The Expr.iColumn field is the index in
** AggInfo.aCol[] or AggInfo.aFunc[] of information needed to generate
** code for that node.
**
** AggInfo.pGroupBy and AggInfo.aFunc.pExpr point to fields within the
** original Select structure that describes the SELECT statement.  These
** fields do not need to be freed when deallocating the AggInfo structure.
*/
struct AggInfo {
  u8 directMode;          /* Direct rendering mode means take data directly
                          ** from source tables rather than from accumulators */
  u8 useSortingIdx;       /* In direct mode, reference the sorting index rather
                          ** than the source table */
  int sortingIdx;         /* Cursor number of the sorting index */
  ExprList *pGroupBy;     /* The group by clause */
  int nSortingColumn;     /* Number of columns in the sorting index */
  struct AggInfo_col {    /* For each column used in source tables */
    Table *pTab;             /* Source table */
    int iTable;              /* Cursor number of the source table */
    int iColumn;             /* Column number within the source table */
    int iSorterColumn;       /* Column number in the sorting index */
    int iMem;                /* Memory location that acts as accumulator */
    Expr *pExpr;             /* The original expression */
  } *aCol;
  int nColumn;            /* Number of used entries in aCol[] */
  int nColumnAlloc;       /* Number of slots allocated for aCol[] */
  int nAccumulator;       /* Number of columns that show through to the output.
                          ** Additional columns are used only as parameters to
                          ** aggregate functions */
  struct AggInfo_func {   /* For each aggregate function */
    Expr *pExpr;             /* Expression encoding the function */
    FuncDef *pFunc;          /* The aggregate function implementation */
    int iMem;                /* Memory location that acts as accumulator */
    int iDistinct;           /* Ephemeral table used to enforce DISTINCT */
  } *aFunc;
  int nFunc;              /* Number of entries in aFunc[] */
  int nFuncAlloc;         /* Number of slots allocated for aFunc[] */
};

/*
** The datatype ynVar is a signed integer, either 16-bit or 32-bit.
** Usually it is 16-bits.  But if SQLITE_MAX_VARIABLE_NUMBER is greater
** than 32767 we have to make it 32-bit.  16-bit is preferred because
** it uses less memory in the Expr object, which is a big memory user
** in systems with lots of prepared statements.  And few applications
** need more than about 10 or 20 variables.  But some extreme users want
** to have prepared statements with over 32767 variables, and for them
** the option is available (at compile-time).
*/
#if SQLITE_MAX_VARIABLE_NUMBER<=32767
typedef i16 ynVar;
#else
typedef int ynVar;
#endif

/*
** Each node of an expression in the parse tree is an instance
** of this structure.
**
** Expr.op is the opcode. The integer parser token codes are reused
** as opcodes here. For example, the parser defines TK_GE to be an integer
** code representing the ">=" operator. This same integer code is reused
** to represent the greater-than-or-equal-to operator in the expression
** tree.
**
** If the expression is an SQL literal (TK_INTEGER, TK_FLOAT, TK_BLOB,
** or TK_STRING), then Expr.token contains the text of the SQL literal. If
** the expression is a variable (TK_VARIABLE), then Expr.token contains the
** variable name. Finally, if the expression is an SQL function (TK_FUNCTION),
** then Expr.token contains the name of the function.
**
** Expr.pRight and Expr.pLeft are the left and right subexpressions of a
** binary operator. Either or both may be NULL.
**
** Expr.x.pList is a list of arguments if the expression is an SQL function,
** a CASE expression or an IN expression of the form "<lhs> IN (<y>, <z>...)".
** Expr.x.pSelect is used if the expression is a sub-select or an expression of
** the form "<lhs> IN (SELECT ...)". If the EP_xIsSelect bit is set in the
** Expr.flags mask, then Expr.x.pSelect is valid. Otherwise, Expr.x.pList is
** valid.
**
** An expression of the form ID or ID.ID refers to a column in a table.
** For such expressions, Expr.op is set to TK_COLUMN and Expr.iTable is
** the integer cursor number of a VDBE cursor pointing to that table and
** Expr.iColumn is the column number for the specific column.  If the
** expression is used as a result in an aggregate SELECT, then the
** value is also stored in the Expr.iAgg column in the aggregate so that
** it can be accessed after all aggregates are computed.
**
** If the expression is an unbound variable marker (a question mark
** character '?' in the original SQL) then the Expr.iTable holds the index
** number for that variable.
**
** If the expression is a subquery then Expr.iColumn holds an integer
** register number containing the result of the subquery.  If the
** subquery gives a constant result, then iTable is -1.  If the subquery
** gives a different answer at different times during statement processing
** then iTable is the address of a subroutine that computes the subquery.
**
** If the Expr is of type OP_Column, and the table it is selecting from
** is a disk table or the "old.*" pseudo-table, then pTab points to the
** corresponding table definition.
**
** ALLOCATION NOTES:
**
** Expr objects can use a lot of memory space in database schema.  To
** help reduce memory requirements, sometimes an Expr object will be
** truncated.  And to reduce the number of memory allocations, sometimes
** two or more Expr objects will be stored in a single memory allocation,
** together with Expr.zToken strings.
**
** If the EP_Reduced and EP_TokenOnly flags are set when
** an Expr object is truncated.  When EP_Reduced is set, then all
** the child Expr objects in the Expr.pLeft and Expr.pRight subtrees
** are contained within the same memory allocation.  Note, however, that
** the subtrees in Expr.x.pList or Expr.x.pSelect are always separately
** allocated, regardless of whether or not EP_Reduced is set.
*/
struct Expr {
  u8 op;                 /* Operation performed by this node */
  char affinity;         /* The affinity of the column or 0 if not a column */
  u16 flags;             /* Various flags.  EP_* See below */
  union {
    char *zToken;          /* Token value. Zero terminated and dequoted */
    int iValue;            /* Integer value if EP_IntValue */
  } u;

  /* If the EP_TokenOnly flag is set in the Expr.flags mask, then no
  ** space is allocated for the fields below this point. An attempt to
  ** access them will result in a segfault or malfunction.
  *********************************************************************/

  Expr *pLeft;           /* Left subnode */
  Expr *pRight;          /* Right subnode */
  union {
    ExprList *pList;     /* Function arguments or in "<expr> IN (<expr-list)" */
    Select *pSelect;     /* Used for sub-selects and "<expr> IN (<select>)" */
  } x;
  CollSeq *pColl;        /* The collation type of the column or 0 */

  /* If the EP_Reduced flag is set in the Expr.flags mask, then no
  ** space is allocated for the fields below this point. An attempt to
  ** access them will result in a segfault or malfunction.
  *********************************************************************/

  int iTable;            /* TK_COLUMN: cursor number of table holding column
                         ** TK_REGISTER: register number
                         ** TK_TRIGGER: 1 -> new, 0 -> old */
  ynVar iColumn;         /* TK_COLUMN: column index.  -1 for rowid.
                         ** TK_VARIABLE: variable number (always >= 1). */
  i16 iAgg;              /* Which entry in pAggInfo->aCol[] or ->aFunc[] */
  i16 iRightJoinTable;   /* If EP_FromJoin, the right table of the join */
  u8 flags2;             /* Second set of flags.  EP2_... */
  u8 op2;                /* If a TK_REGISTER, the original value of Expr.op */
  AggInfo *pAggInfo;     /* Used by TK_AGG_COLUMN and TK_AGG_FUNCTION */
  Table *pTab;           /* Table for TK_COLUMN expressions. */
#if SQLITE_MAX_EXPR_DEPTH>0
  int nHeight;           /* Height of the tree headed by this node */
#endif
};

/*
** The following are the meanings of bits in the Expr.flags field.
*/
#define EP_FromJoin   0x0001  /* Originated in ON or USING clause of a join */
#define EP_Agg        0x0002  /* Contains one or more aggregate functions */
#define EP_Resolved   0x0004  /* IDs have been resolved to COLUMNs */
#define EP_Error      0x0008  /* Expression contains one or more errors */
#define EP_Distinct   0x0010  /* Aggregate function with DISTINCT keyword */
#define EP_VarSelect  0x0020  /* pSelect is correlated, not constant */
#define EP_DblQuoted  0x0040  /* token.z was originally in "..." */
#define EP_InfixFunc  0x0080  /* True for an infix function: LIKE, GLOB, etc */
#define EP_ExpCollate 0x0100  /* Collating sequence specified explicitly */
#define EP_FixedDest  0x0200  /* Result needed in a specific register */
#define EP_IntValue   0x0400  /* Integer value contained in u.iValue */
#define EP_xIsSelect  0x0800  /* x.pSelect is valid (otherwise x.pList is) */

#define EP_Reduced    0x1000  /* Expr struct is EXPR_REDUCEDSIZE bytes only */
#define EP_TokenOnly  0x2000  /* Expr struct is EXPR_TOKENONLYSIZE bytes only */
#define EP_Static     0x4000  /* Held in memory not obtained from malloc() */

/*
** The following are the meanings of bits in the Expr.flags2 field.
*/
#define EP2_MallocedToken  0x0001  /* Need to sqlite3DbFree() Expr.zToken */
#define EP2_Irreducible    0x0002  /* Cannot EXPRDUP_REDUCE this Expr */

/*
** The pseudo-routine sqlite3ExprSetIrreducible sets the EP2_Irreducible
** flag on an expression structure.  This flag is used for VV&A only.  The
** routine is implemented as a macro that only works when in debugging mode,
** so as not to burden production code.
*/
#ifdef SQLITE_DEBUG
# define ExprSetIrreducible(X)  (X)->flags2 |= EP2_Irreducible
#else
# define ExprSetIrreducible(X)
#endif

/*
** These macros can be used to test, set, or clear bits in the
** Expr.flags field.
*/
#define ExprHasProperty(E,P)     (((E)->flags&(P))==(P))
#define ExprHasAnyProperty(E,P)  (((E)->flags&(P))!=0)
#define ExprSetProperty(E,P)     (E)->flags|=(P)
#define ExprClearProperty(E,P)   (E)->flags&=~(P)

/*
** Macros to determine the number of bytes required by a normal Expr
** struct, an Expr struct with the EP_Reduced flag set in Expr.flags
** and an Expr struct with the EP_TokenOnly flag set.
*/
#define EXPR_FULLSIZE           sizeof(Expr)           /* Full size */
#define EXPR_REDUCEDSIZE        offsetof(Expr,iTable)  /* Common features */
#define EXPR_TOKENONLYSIZE      offsetof(Expr,pLeft)   /* Fewer features */

/*
** Flags passed to the sqlite3ExprDup() function. See the header comment
** above sqlite3ExprDup() for details.
*/
#define EXPRDUP_REDUCE         0x0001  /* Used reduced-size Expr nodes */

/*
** A list of expressions.  Each expression may optionally have a
** name.  An expr/name combination can be used in several ways, such
** as the list of "expr AS ID" fields following a "SELECT" or in the
** list of "ID = expr" items in an UPDATE.  A list of expressions can
** also be used as the argument to a function, in which case the a.zName
** field is not used.
*/
struct ExprList {
  int nExpr;             /* Number of expressions on the list */
  int nAlloc;            /* Number of entries allocated below */
  int iECursor;          /* VDBE Cursor associated with this ExprList */
  struct ExprList_item {
    Expr *pExpr;           /* The list of expressions */
    char *zName;           /* Token associated with this expression */
    char *zSpan;           /* Original text of the expression */
    u8 sortOrder;          /* 1 for DESC or 0 for ASC */
    u8 done;               /* A flag to indicate when processing is finished */
    u16 iCol;              /* For ORDER BY, column number in result set */
    u16 iAlias;            /* Index into Parse.aAlias[] for zName */
  } *a;                  /* One entry for each expression */
};

/*
** An instance of this structure is used by the parser to record both
** the parse tree for an expression and the span of input text for an
** expression.
*/
struct ExprSpan {
  Expr *pExpr;          /* The expression parse tree */
  const char *zStart;   /* First character of input text */
  const char *zEnd;     /* One character past the end of input text */
};

/*
** An instance of this structure can hold a simple list of identifiers,
** such as the list "a,b,c" in the following statements:
**
**      INSERT INTO t(a,b,c) VALUES ...;
**      CREATE INDEX idx ON t(a,b,c);
**      CREATE TRIGGER trig BEFORE UPDATE ON t(a,b,c) ...;
**
** The IdList.a.idx field is used when the IdList represents the list of
** column names after a table name in an INSERT statement.  In the statement
**
**     INSERT INTO t(a,b,c) ...
**
** If "a" is the k-th column of table "t", then IdList.a[0].idx==k.
*/
struct IdList {
  struct IdList_item {
    char *zName;      /* Name of the identifier */
    int idx;          /* Index in some Table.aCol[] of a column named zName */
  } *a;
  int nId;         /* Number of identifiers on the list */
  int nAlloc;      /* Number of entries allocated for a[] below */
};

/*
** The bitmask datatype defined below is used for various optimizations.
**
** Changing this from a 64-bit to a 32-bit type limits the number of
** tables in a join to 32 instead of 64.  But it also reduces the size
** of the library by 738 bytes on ix86.
*/
typedef u64 Bitmask;

/*
** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
*/
#define BMS  ((int)(sizeof(Bitmask)*8))

/*
** The following structure describes the FROM clause of a SELECT statement.
** Each table or subquery in the FROM clause is a separate element of
** the SrcList.a[] array.
**
** With the addition of multiple database support, the following structure
** can also be used to describe a particular table such as the table that
** is modified by an INSERT, DELETE, or UPDATE statement.  In standard SQL,
** such a table must be a simple name: ID.  But in SQLite, the table can
** now be identified by a database name, a dot, then the table name: ID.ID.
**
** The jointype starts out showing the join type between the current table
** and the next table on the list.  The parser builds the list this way.
** But sqlite3SrcListShiftJoinType() later shifts the jointypes so that each
** jointype expresses the join between the table and the previous table.
*/
struct SrcList {
  i16 nSrc;        /* Number of tables or subqueries in the FROM clause */
  i16 nAlloc;      /* Number of entries allocated in a[] below */
  struct SrcList_item {
    char *zDatabase;  /* Name of database holding this table */
    char *zName;      /* Name of the table */
    char *zAlias;     /* The "B" part of a "A AS B" phrase.  zName is the "A" */
    Table *pTab;      /* An SQL table corresponding to zName */
    Select *pSelect;  /* A SELECT statement used in place of a table name */
    u8 isPopulated;   /* Temporary table associated with SELECT is populated */
    u8 jointype;      /* Type of join between this able and the previous */
    u8 notIndexed;    /* True if there is a NOT INDEXED clause */
    int iCursor;      /* The VDBE cursor number used to access this table */
    Expr *pOn;        /* The ON clause of a join */
    IdList *pUsing;   /* The USING clause of a join */
    Bitmask colUsed;  /* Bit N (1<<N) set if column N of pTab is used */
    char *zIndex;     /* Identifier from "INDEXED BY <zIndex>" clause */
    Index *pIndex;    /* Index structure corresponding to zIndex, if any */
  } a[1];             /* One entry for each identifier on the list */
};

/*
** Permitted values of the SrcList.a.jointype field
*/
#define JT_INNER     0x0001    /* Any kind of inner or cross join */
#define JT_CROSS     0x0002    /* Explicit use of the CROSS keyword */
#define JT_NATURAL   0x0004    /* True for a "natural" join */
#define JT_LEFT      0x0008    /* Left outer join */
#define JT_RIGHT     0x0010    /* Right outer join */
#define JT_OUTER     0x0020    /* The "OUTER" keyword is present */
#define JT_ERROR     0x0040    /* unknown or unsupported join type */


/*
** A WherePlan object holds information that describes a lookup
** strategy.
**
** This object is intended to be opaque outside of the where.c module.
** It is included here only so that that compiler will know how big it
** is.  None of the fields in this object should be used outside of
** the where.c module.
**
** Within the union, pIdx is only used when wsFlags&WHERE_INDEXED is true.
** pTerm is only used when wsFlags&WHERE_MULTI_OR is true.  And pVtabIdx
** is only used when wsFlags&WHERE_VIRTUALTABLE is true.  It is never the
** case that more than one of these conditions is true.
*/
struct WherePlan {
  u32 wsFlags;                   /* WHERE_* flags that describe the strategy */
  u32 nEq;                       /* Number of == constraints */
  union {
    Index *pIdx;                   /* Index when WHERE_INDEXED is true */
    struct WhereTerm *pTerm;       /* WHERE clause term for OR-search */
    sqlite3_index_info *pVtabIdx;  /* Virtual table index to use */
  } u;
};

/*
** For each nested loop in a WHERE clause implementation, the WhereInfo
** structure contains a single instance of this structure.  This structure
** is intended to be private the the where.c module and should not be
** access or modified by other modules.
**
** The pIdxInfo field is used to help pick the best index on a
** virtual table.  The pIdxInfo pointer contains indexing
** information for the i-th table in the FROM clause before reordering.
** All the pIdxInfo pointers are freed by whereInfoFree() in where.c.
** All other information in the i-th WhereLevel object for the i-th table
** after FROM clause ordering.
*/
struct WhereLevel {
  WherePlan plan;       /* query plan for this element of the FROM clause */
  int iLeftJoin;        /* Memory cell used to implement LEFT OUTER JOIN */
  int iTabCur;          /* The VDBE cursor used to access the table */
  int iIdxCur;          /* The VDBE cursor used to access pIdx */
  int addrBrk;          /* Jump here to break out of the loop */
  int addrNxt;          /* Jump here to start the next IN combination */
  int addrCont;         /* Jump here to continue with the next loop cycle */
  int addrFirst;        /* First instruction of interior of the loop */
  u8 iFrom;             /* Which entry in the FROM clause */
  u8 op, p5;            /* Opcode and P5 of the opcode that ends the loop */
  int p1, p2;           /* Operands of the opcode used to ends the loop */
  union {               /* Information that depends on plan.wsFlags */
    struct {
      int nIn;              /* Number of entries in aInLoop[] */
      struct InLoop {
        int iCur;              /* The VDBE cursor used by this IN operator */
        int addrInTop;         /* Top of the IN loop */
      } *aInLoop;           /* Information about each nested IN operator */
    } in;                 /* Used when plan.wsFlags&WHERE_IN_ABLE */
  } u;

  /* The following field is really not part of the current level.  But
  ** we need a place to cache virtual table index information for each
  ** virtual table in the FROM clause and the WhereLevel structure is
  ** a convenient place since there is one WhereLevel for each FROM clause
  ** element.
  */
  sqlite3_index_info *pIdxInfo;  /* Index info for n-th source table */
};

/*
** Flags appropriate for the wctrlFlags parameter of sqlite3WhereBegin()
** and the WhereInfo.wctrlFlags member.
*/
#define WHERE_ORDERBY_NORMAL   0x0000 /* No-op */
#define WHERE_ORDERBY_MIN      0x0001 /* ORDER BY processing for min() func */
#define WHERE_ORDERBY_MAX      0x0002 /* ORDER BY processing for max() func */
#define WHERE_ONEPASS_DESIRED  0x0004 /* Want to do one-pass UPDATE/DELETE */
#define WHERE_DUPLICATES_OK    0x0008 /* Ok to return a row more than once */
#define WHERE_OMIT_OPEN        0x0010 /* Table cursor are already open */
#define WHERE_OMIT_CLOSE       0x0020 /* Omit close of table & index cursors */
#define WHERE_FORCE_TABLE      0x0040 /* Do not use an index-only search */
#define WHERE_ONETABLE_ONLY    0x0080 /* Only code the 1st table in pTabList */

/*
** The WHERE clause processing routine has two halves.  The
** first part does the start of the WHERE loop and the second
** half does the tail of the WHERE loop.  An instance of
** this structure is returned by the first half and passed
** into the second half to give some continuity.
*/
struct WhereInfo {
  Parse *pParse;       /* Parsing and code generating context */
  u16 wctrlFlags;      /* Flags originally passed to sqlite3WhereBegin() */
  u8 okOnePass;        /* Ok to use one-pass algorithm for UPDATE or DELETE */
  u8 untestedTerms;    /* Not all WHERE terms resolved by outer loop */
  SrcList *pTabList;             /* List of tables in the join */
  int iTop;                      /* The very beginning of the WHERE loop */
  int iContinue;                 /* Jump here to continue with next record */
  int iBreak;                    /* Jump here to break out of the loop */
  int nLevel;                    /* Number of nested loop */
  struct WhereClause *pWC;       /* Decomposition of the WHERE clause */
  WhereLevel a[1];               /* Information about each nest loop in WHERE */
};

/*
** A NameContext defines a context in which to resolve table and column
** names.  The context consists of a list of tables (the pSrcList) field and
** a list of named expression (pEList).  The named expression list may
** be NULL.  The pSrc corresponds to the FROM clause of a SELECT or
** to the table being operated on by INSERT, UPDATE, or DELETE.  The
** pEList corresponds to the result set of a SELECT and is NULL for
** other statements.
**
** NameContexts can be nested.  When resolving names, the inner-most
** context is searched first.  If no match is found, the next outer
** context is checked.  If there is still no match, the next context
** is checked.  This process continues until either a match is found
** or all contexts are check.  When a match is found, the nRef member of
** the context containing the match is incremented.
**
** Each subquery gets a new NameContext.  The pNext field points to the
** NameContext in the parent query.  Thus the process of scanning the
** NameContext list corresponds to searching through successively outer
** subqueries looking for a match.
*/
struct NameContext {
  Parse *pParse;       /* The parser */
  SrcList *pSrcList;   /* One or more tables used to resolve names */
  ExprList *pEList;    /* Optional list of named expressions */
  int nRef;            /* Number of names resolved by this context */
  int nErr;            /* Number of errors encountered while resolving names */
  u8 allowAgg;         /* Aggregate functions allowed here */
  u8 hasAgg;           /* True if aggregates are seen */
  u8 isCheck;          /* True if resolving names in a CHECK constraint */
  int nDepth;          /* Depth of subquery recursion. 1 for no recursion */
  AggInfo *pAggInfo;   /* Information about aggregates at this level */
  NameContext *pNext;  /* Next outer name context.  NULL for outermost */
};

/*
** An instance of the following structure contains all information
** needed to generate code for a single SELECT statement.
**
** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
** If there is a LIMIT clause, the parser sets nLimit to the value of the
** limit and nOffset to the value of the offset (or 0 if there is not
** offset).  But later on, nLimit and nOffset become the memory locations
** in the VDBE that record the limit and offset counters.
**
** addrOpenEphm[] entries contain the address of OP_OpenEphemeral opcodes.
** These addresses must be stored so that we can go back and fill in
** the P4_KEYINFO and P2 parameters later.  Neither the KeyInfo nor
** the number of columns in P2 can be computed at the same time
** as the OP_OpenEphm instruction is coded because not
** enough information about the compound query is known at that point.
** The KeyInfo for addrOpenTran[0] and [1] contains collating sequences
** for the result set.  The KeyInfo for addrOpenTran[2] contains collating
** sequences for the ORDER BY clause.
*/
struct Select {
  ExprList *pEList;      /* The fields of the result */
  u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
  char affinity;         /* MakeRecord with this affinity for SRT_Set */
  u16 selFlags;          /* Various SF_* values */
  SrcList *pSrc;         /* The FROM clause */
  Expr *pWhere;          /* The WHERE clause */
  ExprList *pGroupBy;    /* The GROUP BY clause */
  Expr *pHaving;         /* The HAVING clause */
  ExprList *pOrderBy;    /* The ORDER BY clause */
  Select *pPrior;        /* Prior select in a compound select statement */
  Select *pNext;         /* Next select to the left in a compound */
  Select *pRightmost;    /* Right-most select in a compound select statement */
  Expr *pLimit;          /* LIMIT expression. NULL means not used. */
  Expr *pOffset;         /* OFFSET expression. NULL means not used. */
  int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
  int addrOpenEphm[3];   /* OP_OpenEphem opcodes related to this select */
};

/*
** Allowed values for Select.selFlags.  The "SF" prefix stands for
** "Select Flag".
*/
#define SF_Distinct        0x0001  /* Output should be DISTINCT */
#define SF_Resolved        0x0002  /* Identifiers have been resolved */
#define SF_Aggregate       0x0004  /* Contains aggregate functions */
#define SF_UsesEphemeral   0x0008  /* Uses the OpenEphemeral opcode */
#define SF_Expanded        0x0010  /* sqlite3SelectExpand() called on this */
#define SF_HasTypeInfo     0x0020  /* FROM subqueries have Table metadata */


/*
** The results of a select can be distributed in several ways.  The
** "SRT" prefix means "SELECT Result Type".
*/
#define SRT_Union        1  /* Store result as keys in an index */
#define SRT_Except       2  /* Remove result from a UNION index */
#define SRT_Exists       3  /* Store 1 if the result is not empty */
#define SRT_Discard      4  /* Do not save the results anywhere */

/* The ORDER BY clause is ignored for all of the above */
#define IgnorableOrderby(X) ((X->eDest)<=SRT_Discard)

#define SRT_Output       5  /* Output each row of result */
#define SRT_Mem          6  /* Store result in a memory cell */
#define SRT_Set          7  /* Store results as keys in an index */
#define SRT_Table        8  /* Store result as data with an automatic rowid */
#define SRT_EphemTab     9  /* Create transient tab and store like SRT_Table */
#define SRT_Coroutine   10  /* Generate a single row of result */

/*
** A structure used to customize the behavior of sqlite3Select(). See
** comments above sqlite3Select() for details.
*/
typedef struct SelectDest SelectDest;
struct SelectDest {
  u8 eDest;         /* How to dispose of the results */
  u8 affinity;      /* Affinity used when eDest==SRT_Set */
  int iParm;        /* A parameter used by the eDest disposal method */
  int iMem;         /* Base register where results are written */
  int nMem;         /* Number of registers allocated */
};

/*
** During code generation of statements that do inserts into AUTOINCREMENT
** tables, the following information is attached to the Table.u.autoInc.p
** pointer of each autoincrement table to record some side information that
** the code generator needs.  We have to keep per-table autoincrement
** information in case inserts are down within triggers.  Triggers do not
** normally coordinate their activities, but we do need to coordinate the
** loading and saving of autoincrement information.
*/
struct AutoincInfo {
  AutoincInfo *pNext;   /* Next info block in a list of them all */
  Table *pTab;          /* Table this info block refers to */
  int iDb;              /* Index in sqlite3.aDb[] of database holding pTab */
  int regCtr;           /* Memory register holding the rowid counter */
};

/*
** Size of the column cache
*/
#ifndef SQLITE_N_COLCACHE
# define SQLITE_N_COLCACHE 10
#endif

/*
** At least one instance of the following structure is created for each
** trigger that may be fired while parsing an INSERT, UPDATE or DELETE
** statement. All such objects are stored in the linked list headed at
** Parse.pTriggerPrg and deleted once statement compilation has been
** completed.
**
** A Vdbe sub-program that implements the body and WHEN clause of trigger
** TriggerPrg.pTrigger, assuming a default ON CONFLICT clause of
** TriggerPrg.orconf, is stored in the TriggerPrg.pProgram variable.
** The Parse.pTriggerPrg list never contains two entries with the same
** values for both pTrigger and orconf.
**
** The TriggerPrg.aColmask[0] variable is set to a mask of old.* columns
** accessed (or set to 0 for triggers fired as a result of INSERT
** statements). Similarly, the TriggerPrg.aColmask[1] variable is set to
** a mask of new.* columns used by the program.
*/
struct TriggerPrg {
  Trigger *pTrigger;      /* Trigger this program was coded from */
  int orconf;             /* Default ON CONFLICT policy */
  SubProgram *pProgram;   /* Program implementing pTrigger/orconf */
  u32 aColmask[2];        /* Masks of old.*, new.* columns accessed */
  TriggerPrg *pNext;      /* Next entry in Parse.pTriggerPrg list */
};

/*
** An SQL parser context.  A copy of this structure is passed through
** the parser and down into all the parser action routine in order to
** carry around information that is global to the entire parse.
**
** The structure is divided into two parts.  When the parser and code
** generate call themselves recursively, the first part of the structure
** is constant but the second part is reset at the beginning and end of
** each recursion.
**
** The nTableLock and aTableLock variables are only used if the shared-cache
** feature is enabled (if sqlite3Tsd()->useSharedData is true). They are
** used to store the set of table-locks required by the statement being
** compiled. Function sqlite3TableLock() is used to add entries to the
** list.
*/
struct Parse {
  sqlite3 *db;         /* The main database structure */
  int rc;              /* Return code from execution */
  char *zErrMsg;       /* An error message */
  Vdbe *pVdbe;         /* An engine for executing database bytecode */
  u8 colNamesSet;      /* TRUE after OP_ColumnName has been issued to pVdbe */
  u8 nameClash;        /* A permanent table name clashes with temp table name */
  u8 checkSchema;      /* Causes schema cookie check after an error */
  u8 nested;           /* Number of nested calls to the parser/code generator */
  u8 parseError;       /* True after a parsing error.  Ticket #1794 */
  u8 nTempReg;         /* Number of temporary registers in aTempReg[] */
  u8 nTempInUse;       /* Number of aTempReg[] currently checked out */
  int aTempReg[8];     /* Holding area for temporary registers */
  int nRangeReg;       /* Size of the temporary register block */
  int iRangeReg;       /* First register in temporary register block */
  int nErr;            /* Number of errors seen */
  int nTab;            /* Number of previously allocated VDBE cursors */
  int nMem;            /* Number of memory cells used so far */
  int nSet;            /* Number of sets used so far */
  int ckBase;          /* Base register of data during check constraints */
  int iCacheLevel;     /* ColCache valid when aColCache[].iLevel<=iCacheLevel */
  int iCacheCnt;       /* Counter used to generate aColCache[].lru values */
  u8 nColCache;        /* Number of entries in the column cache */
  u8 iColCache;        /* Next entry of the cache to replace */
  struct yColCache {
    int iTable;           /* Table cursor number */
    int iColumn;          /* Table column number */
    u8 tempReg;           /* iReg is a temp register that needs to be freed */
    int iLevel;           /* Nesting level */
    int iReg;             /* Reg with value of this column. 0 means none. */
    int lru;              /* Least recently used entry has the smallest value */
  } aColCache[SQLITE_N_COLCACHE];  /* One for each column cache entry */
  u32 writeMask;       /* Start a write transaction on these databases */
  u32 cookieMask;      /* Bitmask of schema verified databases */
  u8 isMultiWrite;     /* True if statement may affect/insert multiple rows */
  u8 mayAbort;         /* True if statement may throw an ABORT exception */
  int cookieGoto;      /* Address of OP_Goto to cookie verifier subroutine */
  int cookieValue[SQLITE_MAX_ATTACHED+2];  /* Values of cookies to verify */
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nTableLock;        /* Number of locks in aTableLock */
  TableLock *aTableLock; /* Required table locks for shared-cache mode */
#endif
  int regRowid;        /* Register holding rowid of CREATE TABLE entry */
  int regRoot;         /* Register holding root page number for new objects */
  AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */
  int nMaxArg;         /* Max args passed to user function by sub-program */

  /* Information used while coding trigger programs. */
  Parse *pToplevel;    /* Parse structure for main program (or NULL) */
  Table *pTriggerTab;  /* Table triggers are being coded for */
  u32 oldmask;         /* Mask of old.* columns referenced */
  u32 newmask;         /* Mask of new.* columns referenced */
  u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
  u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
  u8 disableTriggers;  /* True to disable triggers */

  /* Above is constant between recursions.  Below is reset before and after
  ** each recursion */

  int nVar;            /* Number of '?' variables seen in the SQL so far */
  int nVarExpr;        /* Number of used slots in apVarExpr[] */
  int nVarExprAlloc;   /* Number of allocated slots in apVarExpr[] */
  Expr **apVarExpr;    /* Pointers to :aaa and $aaaa wildcard expressions */
  Vdbe *pReprepare;    /* VM being reprepared (sqlite3Reprepare()) */
  int nAlias;          /* Number of aliased result set columns */
  int nAliasAlloc;     /* Number of allocated slots for aAlias[] */
  int *aAlias;         /* Register used to hold aliased result */
  u8 explain;          /* True if the EXPLAIN flag is found on the query */
  Token sNameToken;    /* Token with unqualified schema object name */
  Token sLastToken;    /* The last token parsed */
  const char *zTail;   /* All SQL text past the last semicolon parsed */
  Table *pNewTable;    /* A table being constructed by CREATE TABLE */
  Trigger *pNewTrigger;     /* Trigger under construct by a CREATE TRIGGER */
  const char *zAuthContext; /* The 6th parameter to db->xAuth callbacks */
#ifndef SQLITE_OMIT_VIRTUALTABLE
  Token sArg;                /* Complete text of a module argument */
  u8 declareVtab;            /* True if inside sqlite3_declare_vtab() */
  int nVtabLock;             /* Number of virtual tables to lock */
  Table **apVtabLock;        /* Pointer to virtual tables needing locking */
#endif
  int nHeight;            /* Expression tree height of current sub-select */
  Table *pZombieTab;      /* List of Table objects to delete after code gen */
  TriggerPrg *pTriggerPrg;    /* Linked list of coded triggers */
};

#ifdef SQLITE_OMIT_VIRTUALTABLE
  #define IN_DECLARE_VTAB 0
#else
  #define IN_DECLARE_VTAB (pParse->declareVtab)
#endif

/*
** An instance of the following structure can be declared on a stack and used
** to save the Parse.zAuthContext value so that it can be restored later.
*/
struct AuthContext {
  const char *zAuthContext;   /* Put saved Parse.zAuthContext here */
  Parse *pParse;              /* The Parse structure */
};

/*
** Bitfield flags for P5 value in OP_Insert and OP_Delete
*/
#define OPFLAG_NCHANGE       0x01    /* Set to update db->nChange */
#define OPFLAG_LASTROWID     0x02    /* Set to update db->lastRowid */
#define OPFLAG_ISUPDATE      0x04    /* This OP_Insert is an sql UPDATE */
#define OPFLAG_APPEND        0x08    /* This is likely to be an append */
#define OPFLAG_USESEEKRESULT 0x10    /* Try to avoid a seek in BtreeInsert() */
#define OPFLAG_CLEARCACHE    0x20    /* Clear pseudo-table cache in OP_Column */

/*
 * Each trigger present in the database schema is stored as an instance of
 * struct Trigger.
 *
 * Pointers to instances of struct Trigger are stored in two ways.
 * 1. In the "trigHash" hash table (part of the sqlite3* that represents the
 *    database). This allows Trigger structures to be retrieved by name.
 * 2. All triggers associated with a single table form a linked list, using the
 *    pNext member of struct Trigger. A pointer to the first element of the
 *    linked list is stored as the "pTrigger" member of the associated
 *    struct Table.
 *
 * The "step_list" member points to the first element of a linked list
 * containing the SQL statements specified as the trigger program.
 */
struct Trigger {
  char *zName;            /* The name of the trigger                        */
  char *table;            /* The table or view to which the trigger applies */
  u8 op;                  /* One of TK_DELETE, TK_UPDATE, TK_INSERT         */
  u8 tr_tm;               /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
  Expr *pWhen;            /* The WHEN clause of the expression (may be NULL) */
  IdList *pColumns;       /* If this is an UPDATE OF <column-list> trigger,
                             the <column-list> is stored here */
  Schema *pSchema;        /* Schema containing the trigger */
  Schema *pTabSchema;     /* Schema containing the table */
  TriggerStep *step_list; /* Link list of trigger program steps             */
  Trigger *pNext;         /* Next trigger associated with the table */
};

/*
** A trigger is either a BEFORE or an AFTER trigger.  The following constants
** determine which.
**
** If there are multiple triggers, you might of some BEFORE and some AFTER.
** In that cases, the constants below can be ORed together.
*/
#define TRIGGER_BEFORE  1
#define TRIGGER_AFTER   2

/*
 * An instance of struct TriggerStep is used to store a single SQL statement
 * that is a part of a trigger-program.
 *
 * Instances of struct TriggerStep are stored in a singly linked list (linked
 * using the "pNext" member) referenced by the "step_list" member of the
 * associated struct Trigger instance. The first element of the linked list is
 * the first step of the trigger-program.
 *
 * The "op" member indicates whether this is a "DELETE", "INSERT", "UPDATE" or
 * "SELECT" statement. The meanings of the other members is determined by the
 * value of "op" as follows:
 *
 * (op == TK_INSERT)
 * orconf    -> stores the ON CONFLICT algorithm
 * pSelect   -> If this is an INSERT INTO ... SELECT ... statement, then
 *              this stores a pointer to the SELECT statement. Otherwise NULL.
 * target    -> A token holding the quoted name of the table to insert into.
 * pExprList -> If this is an INSERT INTO ... VALUES ... statement, then
 *              this stores values to be inserted. Otherwise NULL.
 * pIdList   -> If this is an INSERT INTO ... (<column-names>) VALUES ...
 *              statement, then this stores the column-names to be
 *              inserted into.
 *
 * (op == TK_DELETE)
 * target    -> A token holding the quoted name of the table to delete from.
 * pWhere    -> The WHERE clause of the DELETE statement if one is specified.
 *              Otherwise NULL.
 *
 * (op == TK_UPDATE)
 * target    -> A token holding the quoted name of the table to update rows of.
 * pWhere    -> The WHERE clause of the UPDATE statement if one is specified.
 *              Otherwise NULL.
 * pExprList -> A list of the columns to update and the expressions to update
 *              them to. See sqlite3Update() documentation of "pChanges"
 *              argument.
 *
 */
struct TriggerStep {
  u8 op;               /* One of TK_DELETE, TK_UPDATE, TK_INSERT, TK_SELECT */
  u8 orconf;           /* OE_Rollback etc. */
  Trigger *pTrig;      /* The trigger that this step is a part of */
  Select *pSelect;     /* SELECT statment or RHS of INSERT INTO .. SELECT ... */
  Token target;        /* Target table for DELETE, UPDATE, INSERT */
  Expr *pWhere;        /* The WHERE clause for DELETE or UPDATE steps */
  ExprList *pExprList; /* SET clause for UPDATE.  VALUES clause for INSERT */
  IdList *pIdList;     /* Column names for INSERT */
  TriggerStep *pNext;  /* Next in the link-list */
  TriggerStep *pLast;  /* Last element in link-list. Valid for 1st elem only */
};

/*
** The following structure contains information used by the sqliteFix...
** routines as they walk the parse tree to make database references
** explicit.
*/
typedef struct DbFixer DbFixer;
struct DbFixer {
  Parse *pParse;      /* The parsing context.  Error messages written here */
  const char *zDb;    /* Make sure all objects are contained in this database */
  const char *zType;  /* Type of the container - used for error messages */
  const Token *pName; /* Name of the container - used for error messages */
};

/*
** An objected used to accumulate the text of a string where we
** do not necessarily know how big the string will be in the end.
*/
struct StrAccum {
  sqlite3 *db;         /* Optional database for lookaside.  Can be NULL */
  char *zBase;         /* A base allocation.  Not from malloc. */
  char *zText;         /* The string collected so far */
  int  nChar;          /* Length of the string so far */
  int  nAlloc;         /* Amount of space allocated in zText */
  int  mxAlloc;        /* Maximum allowed string length */
  u8   mallocFailed;   /* Becomes true if any memory allocation fails */
  u8   useMalloc;      /* True if zText is enlargeable using realloc */
  u8   tooBig;         /* Becomes true if string size exceeds limits */
};

/*
** A pointer to this structure is used to communicate information
** from sqlite3Init and OP_ParseSchema into the sqlite3InitCallback.
*/
typedef struct {
  sqlite3 *db;        /* The database being initialized */
  int iDb;            /* 0 for main database.  1 for TEMP, 2.. for ATTACHed */
  char **pzErrMsg;    /* Error message stored here */
  int rc;             /* Result code stored here */
} InitData;

/*
** Structure containing global configuration data for the SQLite library.
**
** This structure also contains some state information.
*/
struct Sqlite3Config {
  int bMemstat;                     /* True to enable memory status */
  int bCoreMutex;                   /* True to enable core mutexing */
  int bFullMutex;                   /* True to enable full mutexing */
  int mxStrlen;                     /* Maximum string length */
  int szLookaside;                  /* Default lookaside buffer size */
  int nLookaside;                   /* Default lookaside buffer count */
  sqlite3_mem_methods m;            /* Low-level memory allocation interface */
  sqlite3_mutex_methods mutex;      /* Low-level mutex interface */
  sqlite3_pcache_methods pcache;    /* Low-level page-cache interface */
  void *pHeap;                      /* Heap storage space */
  int nHeap;                        /* Size of pHeap[] */
  int mnReq, mxReq;                 /* Min and max heap requests sizes */
  void *pScratch;                   /* Scratch memory */
  int szScratch;                    /* Size of each scratch buffer */
  int nScratch;                     /* Number of scratch buffers */
  void *pPage;                      /* Page cache memory */
  int szPage;                       /* Size of each page in pPage[] */
  int nPage;                        /* Number of pages in pPage[] */
  int mxParserStack;                /* maximum depth of the parser stack */
  int sharedCacheEnabled;           /* true if shared-cache mode enabled */
  /* The above might be initialized to non-zero.  The following need to always
  ** initially be zero, however. */
  int isInit;                       /* True after initialization has finished */
  int inProgress;                   /* True while initialization in progress */
  int isMutexInit;                  /* True after mutexes are initialized */
  int isMallocInit;                 /* True after malloc is initialized */
  int isPCacheInit;                 /* True after malloc is initialized */
  sqlite3_mutex *pInitMutex;        /* Mutex used by sqlite3_initialize() */
  int nRefInitMutex;                /* Number of users of pInitMutex */
  void (*xLog)(void*,int,const char*); /* Function for logging */
  void *pLogArg;                       /* First argument to xLog() */
};

/*
** Context pointer passed down through the tree-walk.
*/
struct Walker {
  int (*xExprCallback)(Walker*, Expr*);     /* Callback for expressions */
  int (*xSelectCallback)(Walker*,Select*);  /* Callback for SELECTs */
  Parse *pParse;                            /* Parser context.  */
  union {                                   /* Extra data for callback */
    NameContext *pNC;                          /* Naming context */
    int i;                                     /* Integer value */
  } u;
};

/* Forward declarations */
SQLITE_PRIVATE int sqlite3WalkExpr(Walker*, Expr*);
SQLITE_PRIVATE int sqlite3WalkExprList(Walker*, ExprList*);
SQLITE_PRIVATE int sqlite3WalkSelect(Walker*, Select*);
SQLITE_PRIVATE int sqlite3WalkSelectExpr(Walker*, Select*);
SQLITE_PRIVATE int sqlite3WalkSelectFrom(Walker*, Select*);

/*
** Return code from the parse-tree walking primitives and their
** callbacks.
*/
#define WRC_Continue    0   /* Continue down into children */
#define WRC_Prune       1   /* Omit children but continue walking siblings */
#define WRC_Abort       2   /* Abandon the tree walk */

/*
** Assuming zIn points to the first byte of a UTF-8 character,
** advance zIn to point to the first byte of the next UTF-8 character.
*/
#define SQLITE_SKIP_UTF8(zIn) {                        \
  if( (*(zIn++))>=0xc0 ){                              \
    while( (*zIn & 0xc0)==0x80 ){ zIn++; }             \
  }                                                    \
}

/*
** The SQLITE_*_BKPT macros are substitutes for the error codes with
** the same name but without the _BKPT suffix.  These macros invoke
** routines that report the line-number on which the error originated
** using sqlite3_log().  The routines also provide a convenient place
** to set a debugger breakpoint.
*/
SQLITE_PRIVATE int sqlite3CorruptError(int);
SQLITE_PRIVATE int sqlite3MisuseError(int);
SQLITE_PRIVATE int sqlite3CantopenError(int);
#define SQLITE_CORRUPT_BKPT sqlite3CorruptError(__LINE__)
#define SQLITE_MISUSE_BKPT sqlite3MisuseError(__LINE__)
#define SQLITE_CANTOPEN_BKPT sqlite3CantopenError(__LINE__)


/*
** The ctype.h header is needed for non-ASCII systems.  It is also
** needed by FTS3 when FTS3 is included in the amalgamation.
*/
#if !defined(SQLITE_ASCII) || \
    (defined(SQLITE_ENABLE_FTS3) && defined(SQLITE_AMALGAMATION))
# include <ctype.h>
#endif

/*
** The following macros mimic the standard library functions toupper(),
** isspace(), isalnum(), isdigit() and isxdigit(), respectively. The
** sqlite versions only work for ASCII characters, regardless of locale.
*/
#ifdef SQLITE_ASCII
# define sqlite3Toupper(x)  ((x)&~(sqlite3CtypeMap[(unsigned char)(x)]&0x20))
# define sqlite3Isspace(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x01)
# define sqlite3Isalnum(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x06)
# define sqlite3Isalpha(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x02)
# define sqlite3Isdigit(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x04)
# define sqlite3Isxdigit(x)  (sqlite3CtypeMap[(unsigned char)(x)]&0x08)
# define sqlite3Tolower(x)   (sqlite3UpperToLower[(unsigned char)(x)])
#else
# define sqlite3Toupper(x)   toupper((unsigned char)(x))
# define sqlite3Isspace(x)   isspace((unsigned char)(x))
# define sqlite3Isalnum(x)   isalnum((unsigned char)(x))
# define sqlite3Isalpha(x)   isalpha((unsigned char)(x))
# define sqlite3Isdigit(x)   isdigit((unsigned char)(x))
# define sqlite3Isxdigit(x)  isxdigit((unsigned char)(x))
# define sqlite3Tolower(x)   tolower((unsigned char)(x))
#endif

/*
** Internal function prototypes
*/
SQLITE_PRIVATE int sqlite3StrICmp(const char *, const char *);
SQLITE_PRIVATE int sqlite3IsNumber(const char*, int*, u8);
SQLITE_PRIVATE int sqlite3Strlen30(const char*);
#define sqlite3StrNICmp sqlite3_strnicmp

SQLITE_PRIVATE int sqlite3MallocInit(void);
SQLITE_PRIVATE void sqlite3MallocEnd(void);
SQLITE_PRIVATE void *sqlite3Malloc(int);
SQLITE_PRIVATE void *sqlite3MallocZero(int);
SQLITE_PRIVATE void *sqlite3DbMallocZero(sqlite3*, int);
SQLITE_PRIVATE void *sqlite3DbMallocRaw(sqlite3*, int);
SQLITE_PRIVATE char *sqlite3DbStrDup(sqlite3*,const char*);
SQLITE_PRIVATE char *sqlite3DbStrNDup(sqlite3*,const char*, int);
SQLITE_PRIVATE void *sqlite3Realloc(void*, int);
SQLITE_PRIVATE void *sqlite3DbReallocOrFree(sqlite3 *, void *, int);
SQLITE_PRIVATE void *sqlite3DbRealloc(sqlite3 *, void *, int);
SQLITE_PRIVATE void sqlite3DbFree(sqlite3*, void*);
SQLITE_PRIVATE int sqlite3MallocSize(void*);
SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3*, void*);
SQLITE_PRIVATE void *sqlite3ScratchMalloc(int);
SQLITE_PRIVATE void sqlite3ScratchFree(void*);
SQLITE_PRIVATE void *sqlite3PageMalloc(int);
SQLITE_PRIVATE void sqlite3PageFree(void*);
SQLITE_PRIVATE void sqlite3MemSetDefault(void);
SQLITE_PRIVATE void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
SQLITE_PRIVATE int sqlite3MemoryAlarm(void (*)(void*, sqlite3_int64, int), void*, sqlite3_int64);

/*
** On systems with ample stack space and that support alloca(), make
** use of alloca() to obtain space for large automatic objects.  By default,
** obtain space from malloc().
**
** The alloca() routine never returns NULL.  This will cause code paths
** that deal with sqlite3StackAlloc() failures to be unreachable.
*/
#ifdef SQLITE_USE_ALLOCA
# define sqlite3StackAllocRaw(D,N)   alloca(N)
# define sqlite3StackAllocZero(D,N)  memset(alloca(N), 0, N)
# define sqlite3StackFree(D,P)
#else
# define sqlite3StackAllocRaw(D,N)   sqlite3DbMallocRaw(D,N)
# define sqlite3StackAllocZero(D,N)  sqlite3DbMallocZero(D,N)
# define sqlite3StackFree(D,P)       sqlite3DbFree(D,P)
#endif

#ifdef SQLITE_ENABLE_MEMSYS3
SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys3(void);
#endif
#ifdef SQLITE_ENABLE_MEMSYS5
SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys5(void);
#endif


#ifndef SQLITE_MUTEX_OMIT
SQLITE_PRIVATE   sqlite3_mutex_methods *sqlite3DefaultMutex(void);
SQLITE_PRIVATE   sqlite3_mutex *sqlite3MutexAlloc(int);
SQLITE_PRIVATE   int sqlite3MutexInit(void);
SQLITE_PRIVATE   int sqlite3MutexEnd(void);
#endif

SQLITE_PRIVATE int sqlite3StatusValue(int);
SQLITE_PRIVATE void sqlite3StatusAdd(int, int);
SQLITE_PRIVATE void sqlite3StatusSet(int, int);

SQLITE_PRIVATE int sqlite3IsNaN(double);

SQLITE_PRIVATE void sqlite3VXPrintf(StrAccum*, int, const char*, va_list);
#ifndef SQLITE_OMIT_TRACE
SQLITE_PRIVATE void sqlite3XPrintf(StrAccum*, const char*, ...);
#endif
SQLITE_PRIVATE char *sqlite3MPrintf(sqlite3*,const char*, ...);
SQLITE_PRIVATE char *sqlite3VMPrintf(sqlite3*,const char*, va_list);
SQLITE_PRIVATE char *sqlite3MAppendf(sqlite3*,char*,const char*,...);
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
SQLITE_PRIVATE   void sqlite3DebugPrintf(const char*, ...);
#endif
#if defined(SQLITE_TEST)
SQLITE_PRIVATE   void *sqlite3TestTextToPtr(const char*);
#endif
SQLITE_PRIVATE void sqlite3SetString(char **, sqlite3*, const char*, ...);
SQLITE_PRIVATE void sqlite3ErrorMsg(Parse*, const char*, ...);
SQLITE_PRIVATE int sqlite3Dequote(char*);
SQLITE_PRIVATE int sqlite3KeywordCode(const unsigned char*, int);
SQLITE_PRIVATE int sqlite3RunParser(Parse*, const char*, char **);
SQLITE_PRIVATE void sqlite3FinishCoding(Parse*);
SQLITE_PRIVATE int sqlite3GetTempReg(Parse*);
SQLITE_PRIVATE void sqlite3ReleaseTempReg(Parse*,int);
SQLITE_PRIVATE int sqlite3GetTempRange(Parse*,int);
SQLITE_PRIVATE void sqlite3ReleaseTempRange(Parse*,int,int);
SQLITE_PRIVATE Expr *sqlite3ExprAlloc(sqlite3*,int,const Token*,int);
SQLITE_PRIVATE Expr *sqlite3Expr(sqlite3*,int,const char*);
SQLITE_PRIVATE void sqlite3ExprAttachSubtrees(sqlite3*,Expr*,Expr*,Expr*);
SQLITE_PRIVATE Expr *sqlite3PExpr(Parse*, int, Expr*, Expr*, const Token*);
SQLITE_PRIVATE Expr *sqlite3ExprAnd(sqlite3*,Expr*, Expr*);
SQLITE_PRIVATE Expr *sqlite3ExprFunction(Parse*,ExprList*, Token*);
SQLITE_PRIVATE void sqlite3ExprAssignVarNumber(Parse*, Expr*);
SQLITE_PRIVATE void sqlite3ExprDelete(sqlite3*, Expr*);
SQLITE_PRIVATE ExprList *sqlite3ExprListAppend(Parse*,ExprList*,Expr*);
SQLITE_PRIVATE void sqlite3ExprListSetName(Parse*,ExprList*,Token*,int);
SQLITE_PRIVATE void sqlite3ExprListSetSpan(Parse*,ExprList*,ExprSpan*);
SQLITE_PRIVATE void sqlite3ExprListDelete(sqlite3*, ExprList*);
SQLITE_PRIVATE int sqlite3Init(sqlite3*, char**);
SQLITE_PRIVATE int sqlite3InitCallback(void*, int, char**, char**);
SQLITE_PRIVATE void sqlite3Pragma(Parse*,Token*,Token*,Token*,int);
SQLITE_PRIVATE void sqlite3ResetInternalSchema(sqlite3*, int);
SQLITE_PRIVATE void sqlite3BeginParse(Parse*,int);
SQLITE_PRIVATE void sqlite3CommitInternalChanges(sqlite3*);
SQLITE_PRIVATE Table *sqlite3ResultSetOfSelect(Parse*,Select*);
SQLITE_PRIVATE void sqlite3OpenMasterTable(Parse *, int);
SQLITE_PRIVATE void sqlite3StartTable(Parse*,Token*,Token*,int,int,int,int);
SQLITE_PRIVATE void sqlite3AddColumn(Parse*,Token*);
SQLITE_PRIVATE void sqlite3AddNotNull(Parse*, int);
SQLITE_PRIVATE void sqlite3AddPrimaryKey(Parse*, ExprList*, int, int, int);
SQLITE_PRIVATE void sqlite3AddCheckConstraint(Parse*, Expr*);
SQLITE_PRIVATE void sqlite3AddColumnType(Parse*,Token*);
SQLITE_PRIVATE void sqlite3AddDefaultValue(Parse*,ExprSpan*);
SQLITE_PRIVATE void sqlite3AddCollateType(Parse*, Token*);
SQLITE_PRIVATE void sqlite3EndTable(Parse*,Token*,Token*,Select*);

SQLITE_PRIVATE Bitvec *sqlite3BitvecCreate(u32);
SQLITE_PRIVATE int sqlite3BitvecTest(Bitvec*, u32);
SQLITE_PRIVATE int sqlite3BitvecSet(Bitvec*, u32);
SQLITE_PRIVATE void sqlite3BitvecClear(Bitvec*, u32, void*);
SQLITE_PRIVATE void sqlite3BitvecDestroy(Bitvec*);
SQLITE_PRIVATE u32 sqlite3BitvecSize(Bitvec*);
SQLITE_PRIVATE int sqlite3BitvecBuiltinTest(int,int*);

SQLITE_PRIVATE RowSet *sqlite3RowSetInit(sqlite3*, void*, unsigned int);
SQLITE_PRIVATE void sqlite3RowSetClear(RowSet*);
SQLITE_PRIVATE void sqlite3RowSetInsert(RowSet*, i64);
SQLITE_PRIVATE int sqlite3RowSetTest(RowSet*, u8 iBatch, i64);
SQLITE_PRIVATE int sqlite3RowSetNext(RowSet*, i64*);

SQLITE_PRIVATE void sqlite3CreateView(Parse*,Token*,Token*,Token*,Select*,int,int);

#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
SQLITE_PRIVATE   int sqlite3ViewGetColumnNames(Parse*,Table*);
#else
# define sqlite3ViewGetColumnNames(A,B) 0
#endif

SQLITE_PRIVATE void sqlite3DropTable(Parse*, SrcList*, int, int);
SQLITE_PRIVATE void sqlite3DeleteTable(Table*);
#ifndef SQLITE_OMIT_AUTOINCREMENT
SQLITE_PRIVATE   void sqlite3AutoincrementBegin(Parse *pParse);
SQLITE_PRIVATE   void sqlite3AutoincrementEnd(Parse *pParse);
#else
# define sqlite3AutoincrementBegin(X)
# define sqlite3AutoincrementEnd(X)
#endif
SQLITE_PRIVATE void sqlite3Insert(Parse*, SrcList*, ExprList*, Select*, IdList*, int);
SQLITE_PRIVATE void *sqlite3ArrayAllocate(sqlite3*,void*,int,int,int*,int*,int*);
SQLITE_PRIVATE IdList *sqlite3IdListAppend(sqlite3*, IdList*, Token*);
SQLITE_PRIVATE int sqlite3IdListIndex(IdList*,const char*);
SQLITE_PRIVATE SrcList *sqlite3SrcListEnlarge(sqlite3*, SrcList*, int, int);
SQLITE_PRIVATE SrcList *sqlite3SrcListAppend(sqlite3*, SrcList*, Token*, Token*);
SQLITE_PRIVATE SrcList *sqlite3SrcListAppendFromTerm(Parse*, SrcList*, Token*, Token*,
                                      Token*, Select*, Expr*, IdList*);
SQLITE_PRIVATE void sqlite3SrcListIndexedBy(Parse *, SrcList *, Token *);
SQLITE_PRIVATE int sqlite3IndexedByLookup(Parse *, struct SrcList_item *);
SQLITE_PRIVATE void sqlite3SrcListShiftJoinType(SrcList*);
SQLITE_PRIVATE void sqlite3SrcListAssignCursors(Parse*, SrcList*);
SQLITE_PRIVATE void sqlite3IdListDelete(sqlite3*, IdList*);
SQLITE_PRIVATE void sqlite3SrcListDelete(sqlite3*, SrcList*);
SQLITE_PRIVATE Index *sqlite3CreateIndex(Parse*,Token*,Token*,SrcList*,ExprList*,int,Token*,
                        Token*, int, int);
SQLITE_PRIVATE void sqlite3DropIndex(Parse*, SrcList*, int);
SQLITE_PRIVATE int sqlite3Select(Parse*, Select*, SelectDest*);
SQLITE_PRIVATE Select *sqlite3SelectNew(Parse*,ExprList*,SrcList*,Expr*,ExprList*,
                         Expr*,ExprList*,int,Expr*,Expr*);
SQLITE_PRIVATE void sqlite3SelectDelete(sqlite3*, Select*);
SQLITE_PRIVATE Table *sqlite3SrcListLookup(Parse*, SrcList*);
SQLITE_PRIVATE int sqlite3IsReadOnly(Parse*, Table*, int);
SQLITE_PRIVATE void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
SQLITE_PRIVATE Expr *sqlite3LimitWhere(Parse *, SrcList *, Expr *, ExprList *, Expr *, Expr *, char *);
#endif
SQLITE_PRIVATE void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
SQLITE_PRIVATE void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
SQLITE_PRIVATE WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, ExprList**, u16);
SQLITE_PRIVATE void sqlite3WhereEnd(WhereInfo*);
SQLITE_PRIVATE int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int);
SQLITE_PRIVATE void sqlite3ExprCodeMove(Parse*, int, int, int);
SQLITE_PRIVATE void sqlite3ExprCodeCopy(Parse*, int, int, int);
SQLITE_PRIVATE void sqlite3ExprCacheStore(Parse*, int, int, int);
SQLITE_PRIVATE void sqlite3ExprCachePush(Parse*);
SQLITE_PRIVATE void sqlite3ExprCachePop(Parse*, int);
SQLITE_PRIVATE void sqlite3ExprCacheRemove(Parse*, int, int);
SQLITE_PRIVATE void sqlite3ExprCacheClear(Parse*);
SQLITE_PRIVATE void sqlite3ExprCacheAffinityChange(Parse*, int, int);
SQLITE_PRIVATE void sqlite3ExprHardCopy(Parse*,int,int);
SQLITE_PRIVATE int sqlite3ExprCode(Parse*, Expr*, int);
SQLITE_PRIVATE int sqlite3ExprCodeTemp(Parse*, Expr*, int*);
SQLITE_PRIVATE int sqlite3ExprCodeTarget(Parse*, Expr*, int);
SQLITE_PRIVATE int sqlite3ExprCodeAndCache(Parse*, Expr*, int);
SQLITE_PRIVATE void sqlite3ExprCodeConstants(Parse*, Expr*);
SQLITE_PRIVATE int sqlite3ExprCodeExprList(Parse*, ExprList*, int, int);
SQLITE_PRIVATE void sqlite3ExprIfTrue(Parse*, Expr*, int, int);
SQLITE_PRIVATE void sqlite3ExprIfFalse(Parse*, Expr*, int, int);
SQLITE_PRIVATE Table *sqlite3FindTable(sqlite3*,const char*, const char*);
SQLITE_PRIVATE Table *sqlite3LocateTable(Parse*,int isView,const char*, const char*);
SQLITE_PRIVATE Index *sqlite3FindIndex(sqlite3*,const char*, const char*);
SQLITE_PRIVATE void sqlite3UnlinkAndDeleteTable(sqlite3*,int,const char*);
SQLITE_PRIVATE void sqlite3UnlinkAndDeleteIndex(sqlite3*,int,const char*);
SQLITE_PRIVATE void sqlite3Vacuum(Parse*);
SQLITE_PRIVATE int sqlite3RunVacuum(char**, sqlite3*);
SQLITE_PRIVATE char *sqlite3NameFromToken(sqlite3*, Token*);
SQLITE_PRIVATE int sqlite3ExprCompare(Expr*, Expr*);
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
SQLITE_PRIVATE Vdbe *sqlite3GetVdbe(Parse*);
SQLITE_PRIVATE void sqlite3PrngSaveState(void);
SQLITE_PRIVATE void sqlite3PrngRestoreState(void);
SQLITE_PRIVATE void sqlite3PrngResetState(void);
SQLITE_PRIVATE void sqlite3RollbackAll(sqlite3*);
SQLITE_PRIVATE void sqlite3CodeVerifySchema(Parse*, int);
SQLITE_PRIVATE void sqlite3BeginTransaction(Parse*, int);
SQLITE_PRIVATE void sqlite3CommitTransaction(Parse*);
SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse*);
SQLITE_PRIVATE void sqlite3Savepoint(Parse*, int, Token*);
SQLITE_PRIVATE void sqlite3CloseSavepoints(sqlite3 *);
SQLITE_PRIVATE int sqlite3ExprIsConstant(Expr*);
SQLITE_PRIVATE int sqlite3ExprIsConstantNotJoin(Expr*);
SQLITE_PRIVATE int sqlite3ExprIsConstantOrFunction(Expr*);
SQLITE_PRIVATE int sqlite3ExprIsInteger(Expr*, int*);
SQLITE_PRIVATE int sqlite3ExprCanBeNull(const Expr*);
SQLITE_PRIVATE void sqlite3ExprCodeIsNullJump(Vdbe*, const Expr*, int, int);
SQLITE_PRIVATE int sqlite3ExprNeedsNoAffinityChange(const Expr*, char);
SQLITE_PRIVATE int sqlite3IsRowid(const char*);
SQLITE_PRIVATE void sqlite3GenerateRowDelete(Parse*, Table*, int, int, int, Trigger *, int);
SQLITE_PRIVATE void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int*);
SQLITE_PRIVATE int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int);
SQLITE_PRIVATE void sqlite3GenerateConstraintChecks(Parse*,Table*,int,int,
                                     int*,int,int,int,int,int*);
SQLITE_PRIVATE void sqlite3CompleteInsertion(Parse*, Table*, int, int, int*, int, int, int);
SQLITE_PRIVATE int sqlite3OpenTableAndIndices(Parse*, Table*, int, int);
SQLITE_PRIVATE void sqlite3BeginWriteOperation(Parse*, int, int);
SQLITE_PRIVATE void sqlite3MultiWrite(Parse*);
SQLITE_PRIVATE void sqlite3MayAbort(Parse*);
SQLITE_PRIVATE void sqlite3HaltConstraint(Parse*, int, char*, int);
SQLITE_PRIVATE Expr *sqlite3ExprDup(sqlite3*,Expr*,int);
SQLITE_PRIVATE ExprList *sqlite3ExprListDup(sqlite3*,ExprList*,int);
SQLITE_PRIVATE SrcList *sqlite3SrcListDup(sqlite3*,SrcList*,int);
SQLITE_PRIVATE IdList *sqlite3IdListDup(sqlite3*,IdList*);
SQLITE_PRIVATE Select *sqlite3SelectDup(sqlite3*,Select*,int);
SQLITE_PRIVATE void sqlite3FuncDefInsert(FuncDefHash*, FuncDef*);
SQLITE_PRIVATE FuncDef *sqlite3FindFunction(sqlite3*,const char*,int,int,u8,int);
SQLITE_PRIVATE void sqlite3RegisterBuiltinFunctions(sqlite3*);
SQLITE_PRIVATE void sqlite3RegisterDateTimeFunctions(void);
SQLITE_PRIVATE void sqlite3RegisterGlobalFunctions(void);
SQLITE_PRIVATE int sqlite3SafetyCheckOk(sqlite3*);
SQLITE_PRIVATE int sqlite3SafetyCheckSickOrOk(sqlite3*);
SQLITE_PRIVATE void sqlite3ChangeCookie(Parse*, int);

#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
SQLITE_PRIVATE void sqlite3MaterializeView(Parse*, Table*, Expr*, int);
#endif

#ifndef SQLITE_OMIT_TRIGGER
SQLITE_PRIVATE   void sqlite3BeginTrigger(Parse*, Token*,Token*,int,int,IdList*,SrcList*,
                           Expr*,int, int);
SQLITE_PRIVATE   void sqlite3FinishTrigger(Parse*, TriggerStep*, Token*);
SQLITE_PRIVATE   void sqlite3DropTrigger(Parse*, SrcList*, int);
SQLITE_PRIVATE   void sqlite3DropTriggerPtr(Parse*, Trigger*);
SQLITE_PRIVATE   Trigger *sqlite3TriggersExist(Parse *, Table*, int, ExprList*, int *pMask);
SQLITE_PRIVATE   Trigger *sqlite3TriggerList(Parse *, Table *);
SQLITE_PRIVATE   void sqlite3CodeRowTrigger(Parse*, Trigger *, int, ExprList*, int, Table *,
                            int, int, int);
SQLITE_PRIVATE   void sqlite3CodeRowTriggerDirect(Parse *, Trigger *, Table *, int, int, int);
  void sqliteViewTriggers(Parse*, Table*, Expr*, int, ExprList*);
SQLITE_PRIVATE   void sqlite3DeleteTriggerStep(sqlite3*, TriggerStep*);
SQLITE_PRIVATE   TriggerStep *sqlite3TriggerSelectStep(sqlite3*,Select*);
SQLITE_PRIVATE   TriggerStep *sqlite3TriggerInsertStep(sqlite3*,Token*, IdList*,
                                        ExprList*,Select*,u8);
SQLITE_PRIVATE   TriggerStep *sqlite3TriggerUpdateStep(sqlite3*,Token*,ExprList*, Expr*, u8);
SQLITE_PRIVATE   TriggerStep *sqlite3TriggerDeleteStep(sqlite3*,Token*, Expr*);
SQLITE_PRIVATE   void sqlite3DeleteTrigger(sqlite3*, Trigger*);
SQLITE_PRIVATE   void sqlite3UnlinkAndDeleteTrigger(sqlite3*,int,const char*);
SQLITE_PRIVATE   u32 sqlite3TriggerColmask(Parse*,Trigger*,ExprList*,int,int,Table*,int);
# define sqlite3ParseToplevel(p) ((p)->pToplevel ? (p)->pToplevel : (p))
#else
# define sqlite3TriggersExist(B,C,D,E,F) 0
# define sqlite3DeleteTrigger(A,B)
# define sqlite3DropTriggerPtr(A,B)
# define sqlite3UnlinkAndDeleteTrigger(A,B,C)
# define sqlite3CodeRowTrigger(A,B,C,D,E,F,G,H,I)
# define sqlite3CodeRowTriggerDirect(A,B,C,D,E,F)
# define sqlite3TriggerList(X, Y) 0
# define sqlite3ParseToplevel(p) p
# define sqlite3TriggerColmask(A,B,C,D,E,F,G) 0
#endif

SQLITE_PRIVATE int sqlite3JoinType(Parse*, Token*, Token*, Token*);
SQLITE_PRIVATE void sqlite3CreateForeignKey(Parse*, ExprList*, Token*, ExprList*, int);
SQLITE_PRIVATE void sqlite3DeferForeignKey(Parse*, int);
#ifndef SQLITE_OMIT_AUTHORIZATION
SQLITE_PRIVATE   void sqlite3AuthRead(Parse*,Expr*,Schema*,SrcList*);
SQLITE_PRIVATE   int sqlite3AuthCheck(Parse*,int, const char*, const char*, const char*);
SQLITE_PRIVATE   void sqlite3AuthContextPush(Parse*, AuthContext*, const char*);
SQLITE_PRIVATE   void sqlite3AuthContextPop(AuthContext*);
SQLITE_PRIVATE   int sqlite3AuthReadCol(Parse*, const char *, const char *, int);
#else
# define sqlite3AuthRead(a,b,c,d)
# define sqlite3AuthCheck(a,b,c,d,e)    SQLITE_OK
# define sqlite3AuthContextPush(a,b,c)
# define sqlite3AuthContextPop(a)  ((void)(a))
#endif
SQLITE_PRIVATE void sqlite3Attach(Parse*, Expr*, Expr*, Expr*);
SQLITE_PRIVATE void sqlite3Detach(Parse*, Expr*);
SQLITE_PRIVATE int sqlite3BtreeFactory(sqlite3 *db, const char *zFilename,
                       int omitJournal, int nCache, int flags, Btree **ppBtree);
SQLITE_PRIVATE int sqlite3FixInit(DbFixer*, Parse*, int, const char*, const Token*);
SQLITE_PRIVATE int sqlite3FixSrcList(DbFixer*, SrcList*);
SQLITE_PRIVATE int sqlite3FixSelect(DbFixer*, Select*);
SQLITE_PRIVATE int sqlite3FixExpr(DbFixer*, Expr*);
SQLITE_PRIVATE int sqlite3FixExprList(DbFixer*, ExprList*);
SQLITE_PRIVATE int sqlite3FixTriggerStep(DbFixer*, TriggerStep*);
SQLITE_PRIVATE int sqlite3AtoF(const char *z, double*);
SQLITE_PRIVATE int sqlite3GetInt32(const char *, int*);
SQLITE_PRIVATE int sqlite3FitsIn64Bits(const char *, int);
SQLITE_PRIVATE int sqlite3Utf16ByteLen(const void *pData, int nChar);
SQLITE_PRIVATE int sqlite3Utf8CharLen(const char *pData, int nByte);
SQLITE_PRIVATE int sqlite3Utf8Read(const u8*, const u8**);

/*
** Routines to read and write variable-length integers.  These used to
** be defined locally, but now we use the varint routines in the util.c
** file.  Code should use the MACRO forms below, as the Varint32 versions
** are coded to assume the single byte case is already handled (which
** the MACRO form does).
*/
SQLITE_PRIVATE int sqlite3PutVarint(unsigned char*, u64);
SQLITE_PRIVATE int sqlite3PutVarint32(unsigned char*, u32);
SQLITE_PRIVATE u8 sqlite3GetVarint(const unsigned char *, u64 *);
SQLITE_PRIVATE u8 sqlite3GetVarint32(const unsigned char *, u32 *);
SQLITE_PRIVATE int sqlite3VarintLen(u64 v);

/*
** The header of a record consists of a sequence variable-length integers.
** These integers are almost always small and are encoded as a single byte.
** The following macros take advantage this fact to provide a fast encode
** and decode of the integers in a record header.  It is faster for the common
** case where the integer is a single byte.  It is a little slower when the
** integer is two or more bytes.  But overall it is faster.
**
** The following expressions are equivalent:
**
**     x = sqlite3GetVarint32( A, &B );
**     x = sqlite3PutVarint32( A, B );
**
**     x = getVarint32( A, B );
**     x = putVarint32( A, B );
**
*/
#define getVarint32(A,B)  (u8)((*(A)<(u8)0x80) ? ((B) = (u32)*(A)),1 : sqlite3GetVarint32((A), (u32 *)&(B)))
#define putVarint32(A,B)  (u8)(((u32)(B)<(u32)0x80) ? (*(A) = (unsigned char)(B)),1 : sqlite3PutVarint32((A), (B)))
#define getVarint    sqlite3GetVarint
#define putVarint    sqlite3PutVarint


SQLITE_PRIVATE const char *sqlite3IndexAffinityStr(Vdbe *, Index *);
SQLITE_PRIVATE void sqlite3TableAffinityStr(Vdbe *, Table *);
SQLITE_PRIVATE char sqlite3CompareAffinity(Expr *pExpr, char aff2);
SQLITE_PRIVATE int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity);
SQLITE_PRIVATE char sqlite3ExprAffinity(Expr *pExpr);
SQLITE_PRIVATE int sqlite3Atoi64(const char*, i64*);
SQLITE_PRIVATE void sqlite3Error(sqlite3*, int, const char*,...);
SQLITE_PRIVATE void *sqlite3HexToBlob(sqlite3*, const char *z, int n);
SQLITE_PRIVATE int sqlite3TwoPartName(Parse *, Token *, Token *, Token **);
SQLITE_PRIVATE const char *sqlite3ErrStr(int);
SQLITE_PRIVATE int sqlite3ReadSchema(Parse *pParse);
SQLITE_PRIVATE CollSeq *sqlite3FindCollSeq(sqlite3*,u8 enc, const char*,int);
SQLITE_PRIVATE CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
SQLITE_PRIVATE Expr *sqlite3ExprSetColl(Parse *pParse, Expr *, Token *);
SQLITE_PRIVATE int sqlite3CheckCollSeq(Parse *, CollSeq *);
SQLITE_PRIVATE int sqlite3CheckObjectName(Parse *, const char *);
SQLITE_PRIVATE void sqlite3VdbeSetChanges(sqlite3 *, int);

SQLITE_PRIVATE const void *sqlite3ValueText(sqlite3_value*, u8);
SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value*, u8);
SQLITE_PRIVATE void sqlite3ValueSetStr(sqlite3_value*, int, const void *,u8,
                        void(*)(void*));
SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value*);
SQLITE_PRIVATE sqlite3_value *sqlite3ValueNew(sqlite3 *);
SQLITE_PRIVATE char *sqlite3Utf16to8(sqlite3 *, const void*, int);
#ifdef SQLITE_ENABLE_STAT2
SQLITE_PRIVATE char *sqlite3Utf8to16(sqlite3 *, u8, char *, int, int *);
#endif
SQLITE_PRIVATE int sqlite3ValueFromExpr(sqlite3 *, Expr *, u8, u8, sqlite3_value **);
SQLITE_PRIVATE void sqlite3ValueApplyAffinity(sqlite3_value *, u8, u8);
#ifndef SQLITE_AMALGAMATION
SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[];
SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[];
SQLITE_PRIVATE const unsigned char sqlite3CtypeMap[];
SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config;
SQLITE_PRIVATE SQLITE_WSD FuncDefHash sqlite3GlobalFunctions;
SQLITE_PRIVATE int sqlite3PendingByte;
#endif
SQLITE_PRIVATE void sqlite3RootPageMoved(Db*, int, int);
SQLITE_PRIVATE void sqlite3Reindex(Parse*, Token*, Token*);
SQLITE_PRIVATE void sqlite3AlterFunctions(sqlite3*);
SQLITE_PRIVATE void sqlite3AlterRenameTable(Parse*, SrcList*, Token*);
SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *, int *);
SQLITE_PRIVATE void sqlite3NestedParse(Parse*, const char*, ...);
SQLITE_PRIVATE void sqlite3ExpirePreparedStatements(sqlite3*);
SQLITE_PRIVATE int sqlite3CodeSubselect(Parse *, Expr *, int, int);
SQLITE_PRIVATE void sqlite3SelectPrep(Parse*, Select*, NameContext*);
SQLITE_PRIVATE int sqlite3ResolveExprNames(NameContext*, Expr*);
SQLITE_PRIVATE void sqlite3ResolveSelectNames(Parse*, Select*, NameContext*);
SQLITE_PRIVATE int sqlite3ResolveOrderGroupBy(Parse*, Select*, ExprList*, const char*);
SQLITE_PRIVATE void sqlite3ColumnDefault(Vdbe *, Table *, int, int);
SQLITE_PRIVATE void sqlite3AlterFinishAddColumn(Parse *, Token *);
SQLITE_PRIVATE void sqlite3AlterBeginAddColumn(Parse *, SrcList *);
SQLITE_PRIVATE CollSeq *sqlite3GetCollSeq(sqlite3*, u8, CollSeq *, const char*);
SQLITE_PRIVATE char sqlite3AffinityType(const char*);
SQLITE_PRIVATE void sqlite3Analyze(Parse*, Token*, Token*);
SQLITE_PRIVATE int sqlite3InvokeBusyHandler(BusyHandler*);
SQLITE_PRIVATE int sqlite3FindDb(sqlite3*, Token*);
SQLITE_PRIVATE int sqlite3FindDbName(sqlite3 *, const char *);
SQLITE_PRIVATE int sqlite3AnalysisLoad(sqlite3*,int iDB);
SQLITE_PRIVATE void sqlite3DeleteIndexSamples(Index*);
SQLITE_PRIVATE void sqlite3DefaultRowEst(Index*);
SQLITE_PRIVATE void sqlite3RegisterLikeFunctions(sqlite3*, int);
SQLITE_PRIVATE int sqlite3IsLikeFunction(sqlite3*,Expr*,int*,char*);
SQLITE_PRIVATE void sqlite3MinimumFileFormat(Parse*, int, int);
SQLITE_PRIVATE void sqlite3SchemaFree(void *);
SQLITE_PRIVATE Schema *sqlite3SchemaGet(sqlite3 *, Btree *);
SQLITE_PRIVATE int sqlite3SchemaToIndex(sqlite3 *db, Schema *);
SQLITE_PRIVATE KeyInfo *sqlite3IndexKeyinfo(Parse *, Index *);
SQLITE_PRIVATE int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *,
  void (*)(sqlite3_context*,int,sqlite3_value **),
  void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*));
SQLITE_PRIVATE int sqlite3ApiExit(sqlite3 *db, int);
SQLITE_PRIVATE int sqlite3OpenTempDatabase(Parse *);

SQLITE_PRIVATE void sqlite3StrAccumInit(StrAccum*, char*, int, int);
SQLITE_PRIVATE void sqlite3StrAccumAppend(StrAccum*,const char*,int);
SQLITE_PRIVATE char *sqlite3StrAccumFinish(StrAccum*);
SQLITE_PRIVATE void sqlite3StrAccumReset(StrAccum*);
SQLITE_PRIVATE void sqlite3SelectDestInit(SelectDest*,int,int);
SQLITE_PRIVATE Expr *sqlite3CreateColumnExpr(sqlite3 *, SrcList *, int, int);

SQLITE_PRIVATE void sqlite3BackupRestart(sqlite3_backup *);
SQLITE_PRIVATE void sqlite3BackupUpdate(sqlite3_backup *, Pgno, const u8 *);

/*
** The interface to the LEMON-generated parser
*/
SQLITE_PRIVATE void *sqlite3ParserAlloc(void*(*)(size_t));
SQLITE_PRIVATE void sqlite3ParserFree(void*, void(*)(void*));
SQLITE_PRIVATE void sqlite3Parser(void*, int, Token, Parse*);
#ifdef YYTRACKMAXSTACKDEPTH
SQLITE_PRIVATE   int sqlite3ParserStackPeak(void*);
#endif

SQLITE_PRIVATE void sqlite3AutoLoadExtensions(sqlite3*);
#ifndef SQLITE_OMIT_LOAD_EXTENSION
SQLITE_PRIVATE   void sqlite3CloseExtensions(sqlite3*);
#else
# define sqlite3CloseExtensions(X)
#endif

#ifndef SQLITE_OMIT_SHARED_CACHE
SQLITE_PRIVATE   void sqlite3TableLock(Parse *, int, int, u8, const char *);
#else
  #define sqlite3TableLock(v,w,x,y,z)
#endif

#ifdef SQLITE_TEST
SQLITE_PRIVATE   int sqlite3Utf8To8(unsigned char*);
#endif

#ifdef SQLITE_OMIT_VIRTUALTABLE
#  define sqlite3VtabClear(Y)
#  define sqlite3VtabSync(X,Y) SQLITE_OK
#  define sqlite3VtabRollback(X)
#  define sqlite3VtabCommit(X)
#  define sqlite3VtabInSync(db) 0
#  define sqlite3VtabLock(X)
#  define sqlite3VtabUnlock(X)
#  define sqlite3VtabUnlockList(X)
#else
SQLITE_PRIVATE    void sqlite3VtabClear(Table*);
SQLITE_PRIVATE    int sqlite3VtabSync(sqlite3 *db, char **);
SQLITE_PRIVATE    int sqlite3VtabRollback(sqlite3 *db);
SQLITE_PRIVATE    int sqlite3VtabCommit(sqlite3 *db);
SQLITE_PRIVATE    void sqlite3VtabLock(VTable *);
SQLITE_PRIVATE    void sqlite3VtabUnlock(VTable *);
SQLITE_PRIVATE    void sqlite3VtabUnlockList(sqlite3*);
#  define sqlite3VtabInSync(db) ((db)->nVTrans>0 && (db)->aVTrans==0)
#endif
SQLITE_PRIVATE void sqlite3VtabMakeWritable(Parse*,Table*);
SQLITE_PRIVATE void sqlite3VtabBeginParse(Parse*, Token*, Token*, Token*);
SQLITE_PRIVATE void sqlite3VtabFinishParse(Parse*, Token*);
SQLITE_PRIVATE void sqlite3VtabArgInit(Parse*);
SQLITE_PRIVATE void sqlite3VtabArgExtend(Parse*, Token*);
SQLITE_PRIVATE int sqlite3VtabCallCreate(sqlite3*, int, const char *, char **);
SQLITE_PRIVATE int sqlite3VtabCallConnect(Parse*, Table*);
SQLITE_PRIVATE int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
SQLITE_PRIVATE int sqlite3VtabBegin(sqlite3 *, VTable *);
SQLITE_PRIVATE FuncDef *sqlite3VtabOverloadFunction(sqlite3 *,FuncDef*, int nArg, Expr*);
SQLITE_PRIVATE void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
SQLITE_PRIVATE int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
SQLITE_PRIVATE int sqlite3Reprepare(Vdbe*);
SQLITE_PRIVATE void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);
SQLITE_PRIVATE int sqlite3TempInMemory(const sqlite3*);
SQLITE_PRIVATE VTable *sqlite3GetVTable(sqlite3*, Table*);

/* Declarations for functions in fkey.c. All of these are replaced by
** no-op macros if OMIT_FOREIGN_KEY is defined. In this case no foreign
** key functionality is available. If OMIT_TRIGGER is defined but
** OMIT_FOREIGN_KEY is not, only some of the functions are no-oped. In
** this case foreign keys are parsed, but no other functionality is
** provided (enforcement of FK constraints requires the triggers sub-system).
*/
#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
SQLITE_PRIVATE   void sqlite3FkCheck(Parse*, Table*, int, int);
SQLITE_PRIVATE   void sqlite3FkDropTable(Parse*, SrcList *, Table*);
SQLITE_PRIVATE   void sqlite3FkActions(Parse*, Table*, ExprList*, int);
SQLITE_PRIVATE   int sqlite3FkRequired(Parse*, Table*, int*, int);
SQLITE_PRIVATE   u32 sqlite3FkOldmask(Parse*, Table*);
SQLITE_PRIVATE   FKey *sqlite3FkReferences(Table *);
#else
  #define sqlite3FkActions(a,b,c,d)
  #define sqlite3FkCheck(a,b,c,d)
  #define sqlite3FkDropTable(a,b,c)
  #define sqlite3FkOldmask(a,b)      0
  #define sqlite3FkRequired(a,b,c,d) 0
#endif
#ifndef SQLITE_OMIT_FOREIGN_KEY
SQLITE_PRIVATE   void sqlite3FkDelete(Table*);
#else
  #define sqlite3FkDelete(a)
#endif


/*
** Available fault injectors.  Should be numbered beginning with 0.
*/
#define SQLITE_FAULTINJECTOR_MALLOC     0
#define SQLITE_FAULTINJECTOR_COUNT      1

/*
** The interface to the code in fault.c used for identifying "benign"
** malloc failures. This is only present if SQLITE_OMIT_BUILTIN_TEST
** is not defined.
*/
#ifndef SQLITE_OMIT_BUILTIN_TEST
SQLITE_PRIVATE   void sqlite3BeginBenignMalloc(void);
SQLITE_PRIVATE   void sqlite3EndBenignMalloc(void);
#else
  #define sqlite3BeginBenignMalloc()
  #define sqlite3EndBenignMalloc()
#endif

#define IN_INDEX_ROWID           1
#define IN_INDEX_EPH             2
#define IN_INDEX_INDEX           3
SQLITE_PRIVATE int sqlite3FindInIndex(Parse *, Expr *, int*);

#ifdef SQLITE_ENABLE_ATOMIC_WRITE
SQLITE_PRIVATE   int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int);
SQLITE_PRIVATE   int sqlite3JournalSize(sqlite3_vfs *);
SQLITE_PRIVATE   int sqlite3JournalCreate(sqlite3_file *);
#else
  #define sqlite3JournalSize(pVfs) ((pVfs)->szOsFile)
#endif

SQLITE_PRIVATE void sqlite3MemJournalOpen(sqlite3_file *);
SQLITE_PRIVATE int sqlite3MemJournalSize(void);
SQLITE_PRIVATE int sqlite3IsMemJournal(sqlite3_file *);

#if SQLITE_MAX_EXPR_DEPTH>0
SQLITE_PRIVATE   void sqlite3ExprSetHeight(Parse *pParse, Expr *p);
SQLITE_PRIVATE   int sqlite3SelectExprHeight(Select *);
SQLITE_PRIVATE   int sqlite3ExprCheckHeight(Parse*, int);
#else
  #define sqlite3ExprSetHeight(x,y)
  #define sqlite3SelectExprHeight(x) 0
  #define sqlite3ExprCheckHeight(x,y)
#endif

SQLITE_PRIVATE u32 sqlite3Get4byte(const u8*);
SQLITE_PRIVATE void sqlite3Put4byte(u8*, u32);

#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
SQLITE_PRIVATE   void sqlite3ConnectionBlocked(sqlite3 *, sqlite3 *);
SQLITE_PRIVATE   void sqlite3ConnectionUnlocked(sqlite3 *db);
SQLITE_PRIVATE   void sqlite3ConnectionClosed(sqlite3 *db);
#else
  #define sqlite3ConnectionBlocked(x,y)
  #define sqlite3ConnectionUnlocked(x)
  #define sqlite3ConnectionClosed(x)
#endif

#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   void sqlite3ParserTrace(FILE*, char *);
#endif

/*
** If the SQLITE_ENABLE IOTRACE exists then the global variable
** sqlite3IoTrace is a pointer to a printf-like routine used to
** print I/O tracing messages.
*/
#ifdef SQLITE_ENABLE_IOTRACE
# define IOTRACE(A)  if( sqlite3IoTrace ){ sqlite3IoTrace A; }
SQLITE_PRIVATE   void sqlite3VdbeIOTraceSql(Vdbe*);
SQLITE_PRIVATE void (*sqlite3IoTrace)(const char*,...);
#else
# define IOTRACE(A)
# define sqlite3VdbeIOTraceSql(X)
#endif

#endif

/************** End of sqliteInt.h *******************************************/
/************** Begin file global.c ******************************************/
/*
** 2008 June 13
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains definitions of global variables and contants.
*/

/* An array to map all upper-case characters into their corresponding
** lower-case character.
**
** SQLite only considers US-ASCII (or EBCDIC) characters.  We do not
** handle case conversions for the UTF character set since the tables
** involved are nearly as big or bigger than SQLite itself.
*/
SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[] = {
#ifdef SQLITE_ASCII
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17,
     18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
     36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
     54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 97, 98, 99,100,101,102,103,
    104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,
    122, 91, 92, 93, 94, 95, 96, 97, 98, 99,100,101,102,103,104,105,106,107,
    108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,
    126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
    144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,
    162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,
    180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,
    198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,
    216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,
    234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,
    252,253,254,255
#endif
#ifdef SQLITE_EBCDIC
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, /* 0x */
     16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, /* 1x */
     32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, /* 2x */
     48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, /* 3x */
     64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, /* 4x */
     80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, /* 5x */
     96, 97, 66, 67, 68, 69, 70, 71, 72, 73,106,107,108,109,110,111, /* 6x */
    112, 81, 82, 83, 84, 85, 86, 87, 88, 89,122,123,124,125,126,127, /* 7x */
    128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143, /* 8x */
    144,145,146,147,148,149,150,151,152,153,154,155,156,157,156,159, /* 9x */
    160,161,162,163,164,165,166,167,168,169,170,171,140,141,142,175, /* Ax */
    176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191, /* Bx */
    192,129,130,131,132,133,134,135,136,137,202,203,204,205,206,207, /* Cx */
    208,145,146,147,148,149,150,151,152,153,218,219,220,221,222,223, /* Dx */
    224,225,162,163,164,165,166,167,168,169,232,203,204,205,206,207, /* Ex */
    239,240,241,242,243,244,245,246,247,248,249,219,220,221,222,255, /* Fx */
#endif
};

/*
** The following 256 byte lookup table is used to support SQLites built-in
** equivalents to the following standard library functions:
**
**   isspace()                        0x01
**   isalpha()                        0x02
**   isdigit()                        0x04
**   isalnum()                        0x06
**   isxdigit()                       0x08
**   toupper()                        0x20
**   SQLite identifier character      0x40
**
** Bit 0x20 is set if the mapped character requires translation to upper
** case. i.e. if the character is a lower-case ASCII character.
** If x is a lower-case ASCII character, then its upper-case equivalent
** is (x - 0x20). Therefore toupper() can be implemented as:
**
**   (x & ~(map[x]&0x20))
**
** Standard function tolower() is implemented using the sqlite3UpperToLower[]
** array. tolower() is used more often than toupper() by SQLite.
**
** Bit 0x40 is set if the character non-alphanumeric and can be used in an
** SQLite identifier.  Identifiers are alphanumerics, "_", "$", and any
** non-ASCII UTF character. Hence the test for whether or not a character is
** part of an identifier is 0x46.
**
** SQLite's versions are identical to the standard versions assuming a
** locale of "C". They are implemented as macros in sqliteInt.h.
*/
#ifdef SQLITE_ASCII
SQLITE_PRIVATE const unsigned char sqlite3CtypeMap[256] = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 00..07    ........ */
  0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00,  /* 08..0f    ........ */
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 10..17    ........ */
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 18..1f    ........ */
  0x01, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,  /* 20..27     !"#$%&' */
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 28..2f    ()*+,-./ */
  0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c,  /* 30..37    01234567 */
  0x0c, 0x0c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 38..3f    89:;<=>? */

  0x00, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x02,  /* 40..47    @ABCDEFG */
  0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,  /* 48..4f    HIJKLMNO */
  0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,  /* 50..57    PQRSTUVW */
  0x02, 0x02, 0x02, 0x00, 0x00, 0x00, 0x00, 0x40,  /* 58..5f    XYZ[\]^_ */
  0x00, 0x2a, 0x2a, 0x2a, 0x2a, 0x2a, 0x2a, 0x22,  /* 60..67    `abcdefg */
  0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22,  /* 68..6f    hijklmno */
  0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22,  /* 70..77    pqrstuvw */
  0x22, 0x22, 0x22, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 78..7f    xyz{|}~. */

  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 80..87    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 88..8f    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 90..97    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 98..9f    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* a0..a7    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* a8..af    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* b0..b7    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* b8..bf    ........ */

  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* c0..c7    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* c8..cf    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* d0..d7    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* d8..df    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* e0..e7    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* e8..ef    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* f0..f7    ........ */
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40   /* f8..ff    ........ */
};
#endif



/*
** The following singleton contains the global configuration for
** the SQLite library.
*/
SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config = {
   SQLITE_DEFAULT_MEMSTATUS,  /* bMemstat */
   1,                         /* bCoreMutex */
   SQLITE_THREADSAFE==1,      /* bFullMutex */
   0x7ffffffe,                /* mxStrlen */
   100,                       /* szLookaside */
   500,                       /* nLookaside */
   {0,0,0,0,0,0,0,0},         /* m */
   {0,0,0,0,0,0,0,0,0},       /* mutex */
   {0,0,0,0,0,0,0,0,0,0,0},   /* pcache */
   (void*)0,                  /* pHeap */
   0,                         /* nHeap */
   0, 0,                      /* mnHeap, mxHeap */
   (void*)0,                  /* pScratch */
   0,                         /* szScratch */
   0,                         /* nScratch */
   (void*)0,                  /* pPage */
   0,                         /* szPage */
   0,                         /* nPage */
   0,                         /* mxParserStack */
   0,                         /* sharedCacheEnabled */
   /* All the rest should always be initialized to zero */
   0,                         /* isInit */
   0,                         /* inProgress */
   0,                         /* isMutexInit */
   0,                         /* isMallocInit */
   0,                         /* isPCacheInit */
   0,                         /* pInitMutex */
   0,                         /* nRefInitMutex */
   0,                         /* xLog */
   0,                         /* pLogArg */
};


/*
** Hash table for global functions - functions common to all
** database connections.  After initialization, this table is
** read-only.
*/
SQLITE_PRIVATE SQLITE_WSD FuncDefHash sqlite3GlobalFunctions;

/*
** The value of the "pending" byte must be 0x40000000 (1 byte past the
** 1-gibabyte boundary) in a compatible database.  SQLite never uses
** the database page that contains the pending byte.  It never attempts
** to read or write that page.  The pending byte page is set assign
** for use by the VFS layers as space for managing file locks.
**
** During testing, it is often desirable to move the pending byte to
** a different position in the file.  This allows code that has to
** deal with the pending byte to run on files that are much smaller
** than 1 GiB.  The sqlite3_test_control() interface can be used to
** move the pending byte.
**
** IMPORTANT:  Changing the pending byte to any value other than
** 0x40000000 results in an incompatible database file format!
** Changing the pending byte during operating results in undefined
** and dileterious behavior.
*/
SQLITE_PRIVATE int sqlite3PendingByte = 0x40000000;

/*
** Properties of opcodes.  The OPFLG_INITIALIZER macro is
** created by mkopcodeh.awk during compilation.  Data is obtained
** from the comments following the "case OP_xxxx:" statements in
** the vdbe.c file.
*/
SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[] = OPFLG_INITIALIZER;

/************** End of global.c **********************************************/
/************** Begin file status.c ******************************************/
/*
** 2008 June 18
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This module implements the sqlite3_status() interface and related
** functionality.
*/

/*
** Variables in which to record status information.
*/
typedef struct sqlite3StatType sqlite3StatType;
static SQLITE_WSD struct sqlite3StatType {
  int nowValue[9];         /* Current value */
  int mxValue[9];          /* Maximum value */
} sqlite3Stat = { {0,}, {0,} };


/* The "wsdStat" macro will resolve to the status information
** state vector.  If writable static data is unsupported on the target,
** we have to locate the state vector at run-time.  In the more common
** case where writable static data is supported, wsdStat can refer directly
** to the "sqlite3Stat" state vector declared above.
*/
#ifdef SQLITE_OMIT_WSD
# define wsdStatInit  sqlite3StatType *x = &GLOBAL(sqlite3StatType,sqlite3Stat)
# define wsdStat x[0]
#else
# define wsdStatInit
# define wsdStat sqlite3Stat
#endif

/*
** Return the current value of a status parameter.
*/
SQLITE_PRIVATE int sqlite3StatusValue(int op){
  wsdStatInit;
  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
  return wsdStat.nowValue[op];
}

/*
** Add N to the value of a status record.  It is assumed that the
** caller holds appropriate locks.
*/
SQLITE_PRIVATE void sqlite3StatusAdd(int op, int N){
  wsdStatInit;
  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
  wsdStat.nowValue[op] += N;
  if( wsdStat.nowValue[op]>wsdStat.mxValue[op] ){
    wsdStat.mxValue[op] = wsdStat.nowValue[op];
  }
}

/*
** Set the value of a status to X.
*/
SQLITE_PRIVATE void sqlite3StatusSet(int op, int X){
  wsdStatInit;
  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
  wsdStat.nowValue[op] = X;
  if( wsdStat.nowValue[op]>wsdStat.mxValue[op] ){
    wsdStat.mxValue[op] = wsdStat.nowValue[op];
  }
}

/*
** Query status information.
**
** This implementation assumes that reading or writing an aligned
** 32-bit integer is an atomic operation.  If that assumption is not true,
** then this routine is not threadsafe.
*/
SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag){
  wsdStatInit;
  if( op<0 || op>=ArraySize(wsdStat.nowValue) ){
    return SQLITE_MISUSE_BKPT;
  }
  *pCurrent = wsdStat.nowValue[op];
  *pHighwater = wsdStat.mxValue[op];
  if( resetFlag ){
    wsdStat.mxValue[op] = wsdStat.nowValue[op];
  }
  return SQLITE_OK;
}

/*
** Query status information for a single database connection
*/
SQLITE_API int sqlite3_db_status(
  sqlite3 *db,          /* The database connection whose status is desired */
  int op,               /* Status verb */
  int *pCurrent,        /* Write current value here */
  int *pHighwater,      /* Write high-water mark here */
  int resetFlag         /* Reset high-water mark if true */
){
  switch( op ){
    case SQLITE_DBSTATUS_LOOKASIDE_USED: {
      *pCurrent = db->lookaside.nOut;
      *pHighwater = db->lookaside.mxOut;
      if( resetFlag ){
        db->lookaside.mxOut = db->lookaside.nOut;
      }
      break;
    }
    default: {
      return SQLITE_ERROR;
    }
  }
  return SQLITE_OK;
}

/************** End of status.c **********************************************/
/************** Begin file date.c ********************************************/
/*
** 2003 October 31
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement date and time
** functions for SQLite.
**
** There is only one exported symbol in this file - the function
** sqlite3RegisterDateTimeFunctions() found at the bottom of the file.
** All other code has file scope.
**
** SQLite processes all times and dates as Julian Day numbers.  The
** dates and times are stored as the number of days since noon
** in Greenwich on November 24, 4714 B.C. according to the Gregorian
** calendar system.
**
** 1970-01-01 00:00:00 is JD 2440587.5
** 2000-01-01 00:00:00 is JD 2451544.5
**
** This implemention requires years to be expressed as a 4-digit number
** which means that only dates between 0000-01-01 and 9999-12-31 can
** be represented, even though julian day numbers allow a much wider
** range of dates.
**
** The Gregorian calendar system is used for all dates and times,
** even those that predate the Gregorian calendar.  Historians usually
** use the Julian calendar for dates prior to 1582-10-15 and for some
** dates afterwards, depending on locale.  Beware of this difference.
**
** The conversion algorithms are implemented based on descriptions
** in the following text:
**
**      Jean Meeus
**      Astronomical Algorithms, 2nd Edition, 1998
**      ISBM 0-943396-61-1
**      Willmann-Bell, Inc
**      Richmond, Virginia (USA)
*/
#include <time.h>

#ifndef SQLITE_OMIT_DATETIME_FUNCS

/*
** On recent Windows platforms, the localtime_s() function is available
** as part of the "Secure CRT". It is essentially equivalent to
** localtime_r() available under most POSIX platforms, except that the
** order of the parameters is reversed.
**
** See http://msdn.microsoft.com/en-us/library/a442x3ye(VS.80).aspx.
**
** If the user has not indicated to use localtime_r() or localtime_s()
** already, check for an MSVC build environment that provides
** localtime_s().
*/
#if !defined(HAVE_LOCALTIME_R) && !defined(HAVE_LOCALTIME_S) && \
     defined(_MSC_VER) && defined(_CRT_INSECURE_DEPRECATE)
#define HAVE_LOCALTIME_S 1
#endif

/*
** A structure for holding a single date and time.
*/
typedef struct DateTime DateTime;
struct DateTime {
  sqlite3_int64 iJD; /* The julian day number times 86400000 */
  int Y, M, D;       /* Year, month, and day */
  int h, m;          /* Hour and minutes */
  int tz;            /* Timezone offset in minutes */
  double s;          /* Seconds */
  char validYMD;     /* True (1) if Y,M,D are valid */
  char validHMS;     /* True (1) if h,m,s are valid */
  char validJD;      /* True (1) if iJD is valid */
  char validTZ;      /* True (1) if tz is valid */
};


/*
** Convert zDate into one or more integers.  Additional arguments
** come in groups of 5 as follows:
**
**       N       number of digits in the integer
**       min     minimum allowed value of the integer
**       max     maximum allowed value of the integer
**       nextC   first character after the integer
**       pVal    where to write the integers value.
**
** Conversions continue until one with nextC==0 is encountered.
** The function returns the number of successful conversions.
*/
static int getDigits(const char *zDate, ...){
  va_list ap;
  int val;
  int N;
  int min;
  int max;
  int nextC;
  int *pVal;
  int cnt = 0;
  va_start(ap, zDate);
  do{
    N = va_arg(ap, int);
    min = va_arg(ap, int);
    max = va_arg(ap, int);
    nextC = va_arg(ap, int);
    pVal = va_arg(ap, int*);
    val = 0;
    while( N-- ){
      if( !sqlite3Isdigit(*zDate) ){
        goto end_getDigits;
      }
      val = val*10 + *zDate - '0';
      zDate++;
    }
    if( val<min || val>max || (nextC!=0 && nextC!=*zDate) ){
      goto end_getDigits;
    }
    *pVal = val;
    zDate++;
    cnt++;
  }while( nextC );
end_getDigits:
  va_end(ap);
  return cnt;
}

/*
** Read text from z[] and convert into a floating point number.  Return
** the number of digits converted.
*/
#define getValue sqlite3AtoF

/*
** Parse a timezone extension on the end of a date-time.
** The extension is of the form:
**
**        (+/-)HH:MM
**
** Or the "zulu" notation:
**
**        Z
**
** If the parse is successful, write the number of minutes
** of change in p->tz and return 0.  If a parser error occurs,
** return non-zero.
**
** A missing specifier is not considered an error.
*/
static int parseTimezone(const char *zDate, DateTime *p){
  int sgn = 0;
  int nHr, nMn;
  int c;
  while( sqlite3Isspace(*zDate) ){ zDate++; }
  p->tz = 0;
  c = *zDate;
  if( c=='-' ){
    sgn = -1;
  }else if( c=='+' ){
    sgn = +1;
  }else if( c=='Z' || c=='z' ){
    zDate++;
    goto zulu_time;
  }else{
    return c!=0;
  }
  zDate++;
  if( getDigits(zDate, 2, 0, 14, ':', &nHr, 2, 0, 59, 0, &nMn)!=2 ){
    return 1;
  }
  zDate += 5;
  p->tz = sgn*(nMn + nHr*60);
zulu_time:
  while( sqlite3Isspace(*zDate) ){ zDate++; }
  return *zDate!=0;
}

/*
** Parse times of the form HH:MM or HH:MM:SS or HH:MM:SS.FFFF.
** The HH, MM, and SS must each be exactly 2 digits.  The
** fractional seconds FFFF can be one or more digits.
**
** Return 1 if there is a parsing error and 0 on success.
*/
static int parseHhMmSs(const char *zDate, DateTime *p){
  int h, m, s;
  double ms = 0.0;
  if( getDigits(zDate, 2, 0, 24, ':', &h, 2, 0, 59, 0, &m)!=2 ){
    return 1;
  }
  zDate += 5;
  if( *zDate==':' ){
    zDate++;
    if( getDigits(zDate, 2, 0, 59, 0, &s)!=1 ){
      return 1;
    }
    zDate += 2;
    if( *zDate=='.' && sqlite3Isdigit(zDate[1]) ){
      double rScale = 1.0;
      zDate++;
      while( sqlite3Isdigit(*zDate) ){
        ms = ms*10.0 + *zDate - '0';
        rScale *= 10.0;
        zDate++;
      }
      ms /= rScale;
    }
  }else{
    s = 0;
  }
  p->validJD = 0;
  p->validHMS = 1;
  p->h = h;
  p->m = m;
  p->s = s + ms;
  if( parseTimezone(zDate, p) ) return 1;
  p->validTZ = (p->tz!=0)?1:0;
  return 0;
}

/*
** Convert from YYYY-MM-DD HH:MM:SS to julian day.  We always assume
** that the YYYY-MM-DD is according to the Gregorian calendar.
**
** Reference:  Meeus page 61
*/
static void computeJD(DateTime *p){
  int Y, M, D, A, B, X1, X2;

  if( p->validJD ) return;
  if( p->validYMD ){
    Y = p->Y;
    M = p->M;
    D = p->D;
  }else{
    Y = 2000;  /* If no YMD specified, assume 2000-Jan-01 */
    M = 1;
    D = 1;
  }
  if( M<=2 ){
    Y--;
    M += 12;
  }
  A = Y/100;
  B = 2 - A + (A/4);
  X1 = 36525*(Y+4716)/100;
  X2 = 306001*(M+1)/10000;
  p->iJD = (sqlite3_int64)((X1 + X2 + D + B - 1524.5 ) * 86400000);
  p->validJD = 1;
  if( p->validHMS ){
    p->iJD += p->h*3600000 + p->m*60000 + (sqlite3_int64)(p->s*1000);
    if( p->validTZ ){
      p->iJD -= p->tz*60000;
      p->validYMD = 0;
      p->validHMS = 0;
      p->validTZ = 0;
    }
  }
}

/*
** Parse dates of the form
**
**     YYYY-MM-DD HH:MM:SS.FFF
**     YYYY-MM-DD HH:MM:SS
**     YYYY-MM-DD HH:MM
**     YYYY-MM-DD
**
** Write the result into the DateTime structure and return 0
** on success and 1 if the input string is not a well-formed
** date.
*/
static int parseYyyyMmDd(const char *zDate, DateTime *p){
  int Y, M, D, neg;

  if( zDate[0]=='-' ){
    zDate++;
    neg = 1;
  }else{
    neg = 0;
  }
  if( getDigits(zDate,4,0,9999,'-',&Y,2,1,12,'-',&M,2,1,31,0,&D)!=3 ){
    return 1;
  }
  zDate += 10;
  while( sqlite3Isspace(*zDate) || 'T'==*(u8*)zDate ){ zDate++; }
  if( parseHhMmSs(zDate, p)==0 ){
    /* We got the time */
  }else if( *zDate==0 ){
    p->validHMS = 0;
  }else{
    return 1;
  }
  p->validJD = 0;
  p->validYMD = 1;
  p->Y = neg ? -Y : Y;
  p->M = M;
  p->D = D;
  if( p->validTZ ){
    computeJD(p);
  }
  return 0;
}

/*
** Set the time to the current time reported by the VFS
*/
static void setDateTimeToCurrent(sqlite3_context *context, DateTime *p){
  double r;
  sqlite3 *db = sqlite3_context_db_handle(context);
  sqlite3OsCurrentTime(db->pVfs, &r);
  p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
  p->validJD = 1;
}

/*
** Attempt to parse the given string into a Julian Day Number.  Return
** the number of errors.
**
** The following are acceptable forms for the input string:
**
**      YYYY-MM-DD HH:MM:SS.FFF  +/-HH:MM
**      DDDD.DD
**      now
**
** In the first form, the +/-HH:MM is always optional.  The fractional
** seconds extension (the ".FFF") is optional.  The seconds portion
** (":SS.FFF") is option.  The year and date can be omitted as long
** as there is a time string.  The time string can be omitted as long
** as there is a year and date.
*/
static int parseDateOrTime(
  sqlite3_context *context,
  const char *zDate,
  DateTime *p
){
  int isRealNum;    /* Return from sqlite3IsNumber().  Not used */
  if( parseYyyyMmDd(zDate,p)==0 ){
    return 0;
  }else if( parseHhMmSs(zDate, p)==0 ){
    return 0;
  }else if( sqlite3StrICmp(zDate,"now")==0){
    setDateTimeToCurrent(context, p);
    return 0;
  }else if( sqlite3IsNumber(zDate, &isRealNum, SQLITE_UTF8) ){
    double r;
    getValue(zDate, &r);
    p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
    p->validJD = 1;
    return 0;
  }
  return 1;
}

/*
** Compute the Year, Month, and Day from the julian day number.
*/
static void computeYMD(DateTime *p){
  int Z, A, B, C, D, E, X1;
  if( p->validYMD ) return;
  if( !p->validJD ){
    p->Y = 2000;
    p->M = 1;
    p->D = 1;
  }else{
    Z = (int)((p->iJD + 43200000)/86400000);
    A = (int)((Z - 1867216.25)/36524.25);
    A = Z + 1 + A - (A/4);
    B = A + 1524;
    C = (int)((B - 122.1)/365.25);
    D = (36525*C)/100;
    E = (int)((B-D)/30.6001);
    X1 = (int)(30.6001*E);
    p->D = B - D - X1;
    p->M = E<14 ? E-1 : E-13;
    p->Y = p->M>2 ? C - 4716 : C - 4715;
  }
  p->validYMD = 1;
}

/*
** Compute the Hour, Minute, and Seconds from the julian day number.
*/
static void computeHMS(DateTime *p){
  int s;
  if( p->validHMS ) return;
  computeJD(p);
  s = (int)((p->iJD + 43200000) % 86400000);
  p->s = s/1000.0;
  s = (int)p->s;
  p->s -= s;
  p->h = s/3600;
  s -= p->h*3600;
  p->m = s/60;
  p->s += s - p->m*60;
  p->validHMS = 1;
}

/*
** Compute both YMD and HMS
*/
static void computeYMD_HMS(DateTime *p){
  computeYMD(p);
  computeHMS(p);
}

/*
** Clear the YMD and HMS and the TZ
*/
static void clearYMD_HMS_TZ(DateTime *p){
  p->validYMD = 0;
  p->validHMS = 0;
  p->validTZ = 0;
}

#ifndef SQLITE_OMIT_LOCALTIME
/*
** Compute the difference (in milliseconds)
** between localtime and UTC (a.k.a. GMT)
** for the time value p where p is in UTC.
*/
static sqlite3_int64 localtimeOffset(DateTime *p){
  DateTime x, y;
  time_t t;
  x = *p;
  computeYMD_HMS(&x);
  if( x.Y<1971 || x.Y>=2038 ){
    x.Y = 2000;
    x.M = 1;
    x.D = 1;
    x.h = 0;
    x.m = 0;
    x.s = 0.0;
  } else {
    int s = (int)(x.s + 0.5);
    x.s = s;
  }
  x.tz = 0;
  x.validJD = 0;
  computeJD(&x);
  t = (time_t)(x.iJD/1000 - 21086676*(i64)10000);
#ifdef HAVE_LOCALTIME_R
  {
    struct tm sLocal;
    localtime_r(&t, &sLocal);
    y.Y = sLocal.tm_year + 1900;
    y.M = sLocal.tm_mon + 1;
    y.D = sLocal.tm_mday;
    y.h = sLocal.tm_hour;
    y.m = sLocal.tm_min;
    y.s = sLocal.tm_sec;
  }
#elif defined(HAVE_LOCALTIME_S) && HAVE_LOCALTIME_S
  {
    struct tm sLocal;
    localtime_s(&sLocal, &t);
    y.Y = sLocal.tm_year + 1900;
    y.M = sLocal.tm_mon + 1;
    y.D = sLocal.tm_mday;
    y.h = sLocal.tm_hour;
    y.m = sLocal.tm_min;
    y.s = sLocal.tm_sec;
  }
#else
  {
    struct tm *pTm;
    sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
    pTm = localtime(&t);
    y.Y = pTm->tm_year + 1900;
    y.M = pTm->tm_mon + 1;
    y.D = pTm->tm_mday;
    y.h = pTm->tm_hour;
    y.m = pTm->tm_min;
    y.s = pTm->tm_sec;
    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
  }
#endif
  y.validYMD = 1;
  y.validHMS = 1;
  y.validJD = 0;
  y.validTZ = 0;
  computeJD(&y);
  return y.iJD - x.iJD;
}
#endif /* SQLITE_OMIT_LOCALTIME */

/*
** Process a modifier to a date-time stamp.  The modifiers are
** as follows:
**
**     NNN days
**     NNN hours
**     NNN minutes
**     NNN.NNNN seconds
**     NNN months
**     NNN years
**     start of month
**     start of year
**     start of week
**     start of day
**     weekday N
**     unixepoch
**     localtime
**     utc
**
** Return 0 on success and 1 if there is any kind of error.
*/
static int parseModifier(const char *zMod, DateTime *p){
  int rc = 1;
  int n;
  double r;
  char *z, zBuf[30];
  z = zBuf;
  for(n=0; n<ArraySize(zBuf)-1 && zMod[n]; n++){
    z[n] = (char)sqlite3UpperToLower[(u8)zMod[n]];
  }
  z[n] = 0;
  switch( z[0] ){
#ifndef SQLITE_OMIT_LOCALTIME
    case 'l': {
      /*    localtime
      **
      ** Assuming the current time value is UTC (a.k.a. GMT), shift it to
      ** show local time.
      */
      if( strcmp(z, "localtime")==0 ){
        computeJD(p);
        p->iJD += localtimeOffset(p);
        clearYMD_HMS_TZ(p);
        rc = 0;
      }
      break;
    }
#endif
    case 'u': {
      /*
      **    unixepoch
      **
      ** Treat the current value of p->iJD as the number of
      ** seconds since 1970.  Convert to a real julian day number.
      */
      if( strcmp(z, "unixepoch")==0 && p->validJD ){
        p->iJD = (p->iJD + 43200)/86400 + 21086676*(i64)10000000;
        clearYMD_HMS_TZ(p);
        rc = 0;
      }
#ifndef SQLITE_OMIT_LOCALTIME
      else if( strcmp(z, "utc")==0 ){
        sqlite3_int64 c1;
        computeJD(p);
        c1 = localtimeOffset(p);
        p->iJD -= c1;
        clearYMD_HMS_TZ(p);
        p->iJD += c1 - localtimeOffset(p);
        rc = 0;
      }
#endif
      break;
    }
    case 'w': {
      /*
      **    weekday N
      **
      ** Move the date to the same time on the next occurrence of
      ** weekday N where 0==Sunday, 1==Monday, and so forth.  If the
      ** date is already on the appropriate weekday, this is a no-op.
      */
      if( strncmp(z, "weekday ", 8)==0 && getValue(&z[8],&r)>0
                 && (n=(int)r)==r && n>=0 && r<7 ){
        sqlite3_int64 Z;
        computeYMD_HMS(p);
        p->validTZ = 0;
        p->validJD = 0;
        computeJD(p);
        Z = ((p->iJD + 129600000)/86400000) % 7;
        if( Z>n ) Z -= 7;
        p->iJD += (n - Z)*86400000;
        clearYMD_HMS_TZ(p);
        rc = 0;
      }
      break;
    }
    case 's': {
      /*
      **    start of TTTTT
      **
      ** Move the date backwards to the beginning of the current day,
      ** or month or year.
      */
      if( strncmp(z, "start of ", 9)!=0 ) break;
      z += 9;
      computeYMD(p);
      p->validHMS = 1;
      p->h = p->m = 0;
      p->s = 0.0;
      p->validTZ = 0;
      p->validJD = 0;
      if( strcmp(z,"month")==0 ){
        p->D = 1;
        rc = 0;
      }else if( strcmp(z,"year")==0 ){
        computeYMD(p);
        p->M = 1;
        p->D = 1;
        rc = 0;
      }else if( strcmp(z,"day")==0 ){
        rc = 0;
      }
      break;
    }
    case '+':
    case '-':
    case '0':
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
    case '8':
    case '9': {
      double rRounder;
      n = getValue(z, &r);
      assert( n>=1 );
      if( z[n]==':' ){
        /* A modifier of the form (+|-)HH:MM:SS.FFF adds (or subtracts) the
        ** specified number of hours, minutes, seconds, and fractional seconds
        ** to the time.  The ".FFF" may be omitted.  The ":SS.FFF" may be
        ** omitted.
        */
        const char *z2 = z;
        DateTime tx;
        sqlite3_int64 day;
        if( !sqlite3Isdigit(*z2) ) z2++;
        memset(&tx, 0, sizeof(tx));
        if( parseHhMmSs(z2, &tx) ) break;
        computeJD(&tx);
        tx.iJD -= 43200000;
        day = tx.iJD/86400000;
        tx.iJD -= day*86400000;
        if( z[0]=='-' ) tx.iJD = -tx.iJD;
        computeJD(p);
        clearYMD_HMS_TZ(p);
        p->iJD += tx.iJD;
        rc = 0;
        break;
      }
      z += n;
      while( sqlite3Isspace(*z) ) z++;
      n = sqlite3Strlen30(z);
      if( n>10 || n<3 ) break;
      if( z[n-1]=='s' ){ z[n-1] = 0; n--; }
      computeJD(p);
      rc = 0;
      rRounder = r<0 ? -0.5 : +0.5;
      if( n==3 && strcmp(z,"day")==0 ){
        p->iJD += (sqlite3_int64)(r*86400000.0 + rRounder);
      }else if( n==4 && strcmp(z,"hour")==0 ){
        p->iJD += (sqlite3_int64)(r*(86400000.0/24.0) + rRounder);
      }else if( n==6 && strcmp(z,"minute")==0 ){
        p->iJD += (sqlite3_int64)(r*(86400000.0/(24.0*60.0)) + rRounder);
      }else if( n==6 && strcmp(z,"second")==0 ){
        p->iJD += (sqlite3_int64)(r*(86400000.0/(24.0*60.0*60.0)) + rRounder);
      }else if( n==5 && strcmp(z,"month")==0 ){
        int x, y;
        computeYMD_HMS(p);
        p->M += (int)r;
        x = p->M>0 ? (p->M-1)/12 : (p->M-12)/12;
        p->Y += x;
        p->M -= x*12;
        p->validJD = 0;
        computeJD(p);
        y = (int)r;
        if( y!=r ){
          p->iJD += (sqlite3_int64)((r - y)*30.0*86400000.0 + rRounder);
        }
      }else if( n==4 && strcmp(z,"year")==0 ){
        int y = (int)r;
        computeYMD_HMS(p);
        p->Y += y;
        p->validJD = 0;
        computeJD(p);
        if( y!=r ){
          p->iJD += (sqlite3_int64)((r - y)*365.0*86400000.0 + rRounder);
        }
      }else{
        rc = 1;
      }
      clearYMD_HMS_TZ(p);
      break;
    }
    default: {
      break;
    }
  }
  return rc;
}

/*
** Process time function arguments.  argv[0] is a date-time stamp.
** argv[1] and following are modifiers.  Parse them all and write
** the resulting time into the DateTime structure p.  Return 0
** on success and 1 if there are any errors.
**
** If there are zero parameters (if even argv[0] is undefined)
** then assume a default value of "now" for argv[0].
*/
static int isDate(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv,
  DateTime *p
){
  int i;
  const unsigned char *z;
  int eType;
  memset(p, 0, sizeof(*p));
  if( argc==0 ){
    setDateTimeToCurrent(context, p);
  }else if( (eType = sqlite3_value_type(argv[0]))==SQLITE_FLOAT
                   || eType==SQLITE_INTEGER ){
    p->iJD = (sqlite3_int64)(sqlite3_value_double(argv[0])*86400000.0 + 0.5);
    p->validJD = 1;
  }else{
    z = sqlite3_value_text(argv[0]);
    if( !z || parseDateOrTime(context, (char*)z, p) ){
      return 1;
    }
  }
  for(i=1; i<argc; i++){
    if( (z = sqlite3_value_text(argv[i]))==0 || parseModifier((char*)z, p) ){
      return 1;
    }
  }
  return 0;
}


/*
** The following routines implement the various date and time functions
** of SQLite.
*/

/*
**    julianday( TIMESTRING, MOD, MOD, ...)
**
** Return the julian day number of the date specified in the arguments
*/
static void juliandayFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  DateTime x;
  if( isDate(context, argc, argv, &x)==0 ){
    computeJD(&x);
    sqlite3_result_double(context, x.iJD/86400000.0);
  }
}

/*
**    datetime( TIMESTRING, MOD, MOD, ...)
**
** Return YYYY-MM-DD HH:MM:SS
*/
static void datetimeFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  DateTime x;
  if( isDate(context, argc, argv, &x)==0 ){
    char zBuf[100];
    computeYMD_HMS(&x);
    sqlite3_snprintf(sizeof(zBuf), zBuf, "%04d-%02d-%02d %02d:%02d:%02d",
                     x.Y, x.M, x.D, x.h, x.m, (int)(x.s));
    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
  }
}

/*
**    time( TIMESTRING, MOD, MOD, ...)
**
** Return HH:MM:SS
*/
static void timeFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  DateTime x;
  if( isDate(context, argc, argv, &x)==0 ){
    char zBuf[100];
    computeHMS(&x);
    sqlite3_snprintf(sizeof(zBuf), zBuf, "%02d:%02d:%02d", x.h, x.m, (int)x.s);
    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
  }
}

/*
**    date( TIMESTRING, MOD, MOD, ...)
**
** Return YYYY-MM-DD
*/
static void dateFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  DateTime x;
  if( isDate(context, argc, argv, &x)==0 ){
    char zBuf[100];
    computeYMD(&x);
    sqlite3_snprintf(sizeof(zBuf), zBuf, "%04d-%02d-%02d", x.Y, x.M, x.D);
    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
  }
}

/*
**    strftime( FORMAT, TIMESTRING, MOD, MOD, ...)
**
** Return a string described by FORMAT.  Conversions as follows:
**
**   %d  day of month
**   %f  ** fractional seconds  SS.SSS
**   %H  hour 00-24
**   %j  day of year 000-366
**   %J  ** Julian day number
**   %m  month 01-12
**   %M  minute 00-59
**   %s  seconds since 1970-01-01
**   %S  seconds 00-59
**   %w  day of week 0-6  sunday==0
**   %W  week of year 00-53
**   %Y  year 0000-9999
**   %%  %
*/
static void strftimeFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  DateTime x;
  u64 n;
  size_t i,j;
  char *z;
  sqlite3 *db;
  const char *zFmt = (const char*)sqlite3_value_text(argv[0]);
  char zBuf[100];
  if( zFmt==0 || isDate(context, argc-1, argv+1, &x) ) return;
  db = sqlite3_context_db_handle(context);
  for(i=0, n=1; zFmt[i]; i++, n++){
    if( zFmt[i]=='%' ){
      switch( zFmt[i+1] ){
        case 'd':
        case 'H':
        case 'm':
        case 'M':
        case 'S':
        case 'W':
          n++;
          /* fall thru */
        case 'w':
        case '%':
          break;
        case 'f':
          n += 8;
          break;
        case 'j':
          n += 3;
          break;
        case 'Y':
          n += 8;
          break;
        case 's':
        case 'J':
          n += 50;
          break;
        default:
          return;  /* ERROR.  return a NULL */
      }
      i++;
    }
  }
  testcase( n==sizeof(zBuf)-1 );
  testcase( n==sizeof(zBuf) );
  testcase( n==(u64)db->aLimit[SQLITE_LIMIT_LENGTH]+1 );
  testcase( n==(u64)db->aLimit[SQLITE_LIMIT_LENGTH] );
  if( n<sizeof(zBuf) ){
    z = zBuf;
  }else if( n>(u64)db->aLimit[SQLITE_LIMIT_LENGTH] ){
    sqlite3_result_error_toobig(context);
    return;
  }else{
    z = sqlite3DbMallocRaw(db, (int)n);
    if( z==0 ){
      sqlite3_result_error_nomem(context);
      return;
    }
  }
  computeJD(&x);
  computeYMD_HMS(&x);
  for(i=j=0; zFmt[i]; i++){
    if( zFmt[i]!='%' ){
      z[j++] = zFmt[i];
    }else{
      i++;
      switch( zFmt[i] ){
        case 'd':  sqlite3_snprintf(3, &z[j],"%02d",x.D); j+=2; break;
        case 'f': {
          double s = x.s;
          if( s>59.999 ) s = 59.999;
          sqlite3_snprintf(7, &z[j],"%06.3f", s);
          j += sqlite3Strlen30(&z[j]);
          break;
        }
        case 'H':  sqlite3_snprintf(3, &z[j],"%02d",x.h); j+=2; break;
        case 'W': /* Fall thru */
        case 'j': {
          int nDay;             /* Number of days since 1st day of year */
          DateTime y = x;
          y.validJD = 0;
          y.M = 1;
          y.D = 1;
          computeJD(&y);
          nDay = (int)((x.iJD-y.iJD+43200000)/86400000);
          if( zFmt[i]=='W' ){
            int wd;   /* 0=Monday, 1=Tuesday, ... 6=Sunday */
            wd = (int)(((x.iJD+43200000)/86400000)%7);
            sqlite3_snprintf(3, &z[j],"%02d",(nDay+7-wd)/7);
            j += 2;
          }else{
            sqlite3_snprintf(4, &z[j],"%03d",nDay+1);
            j += 3;
          }
          break;
        }
        case 'J': {
          sqlite3_snprintf(20, &z[j],"%.16g",x.iJD/86400000.0);
          j+=sqlite3Strlen30(&z[j]);
          break;
        }
        case 'm':  sqlite3_snprintf(3, &z[j],"%02d",x.M); j+=2; break;
        case 'M':  sqlite3_snprintf(3, &z[j],"%02d",x.m); j+=2; break;
        case 's': {
          sqlite3_snprintf(30,&z[j],"%lld",
                           (i64)(x.iJD/1000 - 21086676*(i64)10000));
          j += sqlite3Strlen30(&z[j]);
          break;
        }
        case 'S':  sqlite3_snprintf(3,&z[j],"%02d",(int)x.s); j+=2; break;
        case 'w': {
          z[j++] = (char)(((x.iJD+129600000)/86400000) % 7) + '0';
          break;
        }
        case 'Y': {
          sqlite3_snprintf(5,&z[j],"%04d",x.Y); j+=sqlite3Strlen30(&z[j]);
          break;
        }
        default:   z[j++] = '%'; break;
      }
    }
  }
  z[j] = 0;
  sqlite3_result_text(context, z, -1,
                      z==zBuf ? SQLITE_TRANSIENT : SQLITE_DYNAMIC);
}

/*
** current_time()
**
** This function returns the same value as time('now').
*/
static void ctimeFunc(
  sqlite3_context *context,
  int NotUsed,
  sqlite3_value **NotUsed2
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  timeFunc(context, 0, 0);
}

/*
** current_date()
**
** This function returns the same value as date('now').
*/
static void cdateFunc(
  sqlite3_context *context,
  int NotUsed,
  sqlite3_value **NotUsed2
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  dateFunc(context, 0, 0);
}

/*
** current_timestamp()
**
** This function returns the same value as datetime('now').
*/
static void ctimestampFunc(
  sqlite3_context *context,
  int NotUsed,
  sqlite3_value **NotUsed2
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  datetimeFunc(context, 0, 0);
}
#endif /* !defined(SQLITE_OMIT_DATETIME_FUNCS) */

#ifdef SQLITE_OMIT_DATETIME_FUNCS
/*
** If the library is compiled to omit the full-scale date and time
** handling (to get a smaller binary), the following minimal version
** of the functions current_time(), current_date() and current_timestamp()
** are included instead. This is to support column declarations that
** include "DEFAULT CURRENT_TIME" etc.
**
** This function uses the C-library functions time(), gmtime()
** and strftime(). The format string to pass to strftime() is supplied
** as the user-data for the function.
*/
static void currentTimeFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  time_t t;
  char *zFormat = (char *)sqlite3_user_data(context);
  sqlite3 *db;
  double rT;
  char zBuf[20];

  UNUSED_PARAMETER(argc);
  UNUSED_PARAMETER(argv);

  db = sqlite3_context_db_handle(context);
  sqlite3OsCurrentTime(db->pVfs, &rT);
#ifndef SQLITE_OMIT_FLOATING_POINT
  t = 86400.0*(rT - 2440587.5) + 0.5;
#else
  /* without floating point support, rT will have
  ** already lost fractional day precision.
  */
  t = 86400 * (rT - 2440587) - 43200;
#endif
#ifdef HAVE_GMTIME_R
  {
    struct tm sNow;
    gmtime_r(&t, &sNow);
    strftime(zBuf, 20, zFormat, &sNow);
  }
#else
  {
    struct tm *pTm;
    sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
    pTm = gmtime(&t);
    strftime(zBuf, 20, zFormat, pTm);
    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
  }
#endif

  sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
}
#endif

/*
** This function registered all of the above C functions as SQL
** functions.  This should be the only routine in this file with
** external linkage.
*/
SQLITE_PRIVATE void sqlite3RegisterDateTimeFunctions(void){
  static SQLITE_WSD FuncDef aDateTimeFuncs[] = {
#ifndef SQLITE_OMIT_DATETIME_FUNCS
    FUNCTION(julianday,        -1, 0, 0, juliandayFunc ),
    FUNCTION(date,             -1, 0, 0, dateFunc      ),
    FUNCTION(time,             -1, 0, 0, timeFunc      ),
    FUNCTION(datetime,         -1, 0, 0, datetimeFunc  ),
    FUNCTION(strftime,         -1, 0, 0, strftimeFunc  ),
    FUNCTION(current_time,      0, 0, 0, ctimeFunc     ),
    FUNCTION(current_timestamp, 0, 0, 0, ctimestampFunc),
    FUNCTION(current_date,      0, 0, 0, cdateFunc     ),
#else
    STR_FUNCTION(current_time,      0, "%H:%M:%S",          0, currentTimeFunc),
    STR_FUNCTION(current_timestamp, 0, "%Y-%m-%d",          0, currentTimeFunc),
    STR_FUNCTION(current_date,      0, "%Y-%m-%d %H:%M:%S", 0, currentTimeFunc),
#endif
  };
  int i;
  FuncDefHash *pHash = &GLOBAL(FuncDefHash, sqlite3GlobalFunctions);
  FuncDef *aFunc = (FuncDef*)&GLOBAL(FuncDef, aDateTimeFuncs);

  for(i=0; i<ArraySize(aDateTimeFuncs); i++){
    sqlite3FuncDefInsert(pHash, &aFunc[i]);
  }
}

/************** End of date.c ************************************************/
/************** Begin file os.c **********************************************/
/*
** 2005 November 29
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains OS interface code that is common to all
** architectures.
*/
#define _SQLITE_OS_C_ 1
#undef _SQLITE_OS_C_

/*
** The default SQLite sqlite3_vfs implementations do not allocate
** memory (actually, os_unix.c allocates a small amount of memory
** from within OsOpen()), but some third-party implementations may.
** So we test the effects of a malloc() failing and the sqlite3OsXXX()
** function returning SQLITE_IOERR_NOMEM using the DO_OS_MALLOC_TEST macro.
**
** The following functions are instrumented for malloc() failure
** testing:
**
**     sqlite3OsOpen()
**     sqlite3OsRead()
**     sqlite3OsWrite()
**     sqlite3OsSync()
**     sqlite3OsLock()
**
*/
#if defined(SQLITE_TEST) && (SQLITE_OS_WIN==0)
  #define DO_OS_MALLOC_TEST(x) if (!x || !sqlite3IsMemJournal(x)) {     \
    void *pTstAlloc = sqlite3Malloc(10);                             \
    if (!pTstAlloc) return SQLITE_IOERR_NOMEM;                       \
    sqlite3_free(pTstAlloc);                                         \
  }
#else
  #define DO_OS_MALLOC_TEST(x)
#endif

/*
** The following routines are convenience wrappers around methods
** of the sqlite3_file object.  This is mostly just syntactic sugar. All
** of this would be completely automatic if SQLite were coded using
** C++ instead of plain old C.
*/
SQLITE_PRIVATE int sqlite3OsClose(sqlite3_file *pId){
  int rc = SQLITE_OK;
  if( pId->pMethods ){
    rc = pId->pMethods->xClose(pId);
    pId->pMethods = 0;
  }
  return rc;
}
SQLITE_PRIVATE int sqlite3OsRead(sqlite3_file *id, void *pBuf, int amt, i64 offset){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xRead(id, pBuf, amt, offset);
}
SQLITE_PRIVATE int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xWrite(id, pBuf, amt, offset);
}
SQLITE_PRIVATE int sqlite3OsTruncate(sqlite3_file *id, i64 size){
  return id->pMethods->xTruncate(id, size);
}
SQLITE_PRIVATE int sqlite3OsSync(sqlite3_file *id, int flags){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xSync(id, flags);
}
SQLITE_PRIVATE int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xFileSize(id, pSize);
}
SQLITE_PRIVATE int sqlite3OsLock(sqlite3_file *id, int lockType){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xLock(id, lockType);
}
SQLITE_PRIVATE int sqlite3OsUnlock(sqlite3_file *id, int lockType){
  return id->pMethods->xUnlock(id, lockType);
}
SQLITE_PRIVATE int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xCheckReservedLock(id, pResOut);
}
SQLITE_PRIVATE int sqlite3OsFileControl(sqlite3_file *id, int op, void *pArg){
  return id->pMethods->xFileControl(id, op, pArg);
}
SQLITE_PRIVATE int sqlite3OsSectorSize(sqlite3_file *id){
  int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;
  return (xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE);
}
SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
  return id->pMethods->xDeviceCharacteristics(id);
}

/*
** The next group of routines are convenience wrappers around the
** VFS methods.
*/
SQLITE_PRIVATE int sqlite3OsOpen(
  sqlite3_vfs *pVfs,
  const char *zPath,
  sqlite3_file *pFile,
  int flags,
  int *pFlagsOut
){
  int rc;
  DO_OS_MALLOC_TEST(0);
  /* 0x7f1f is a mask of SQLITE_OPEN_ flags that are valid to be passed
  ** down into the VFS layer.  Some SQLITE_OPEN_ flags (for example,
  ** SQLITE_OPEN_FULLMUTEX or SQLITE_OPEN_SHAREDCACHE) are blocked before
  ** reaching the VFS. */
  rc = pVfs->xOpen(pVfs, zPath, pFile, flags & 0x7f1f, pFlagsOut);
  assert( rc==SQLITE_OK || pFile->pMethods==0 );
  return rc;
}
SQLITE_PRIVATE int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
  return pVfs->xDelete(pVfs, zPath, dirSync);
}
SQLITE_PRIVATE int sqlite3OsAccess(
  sqlite3_vfs *pVfs,
  const char *zPath,
  int flags,
  int *pResOut
){
  DO_OS_MALLOC_TEST(0);
  return pVfs->xAccess(pVfs, zPath, flags, pResOut);
}
SQLITE_PRIVATE int sqlite3OsFullPathname(
  sqlite3_vfs *pVfs,
  const char *zPath,
  int nPathOut,
  char *zPathOut
){
  zPathOut[0] = 0;
  return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
}
#ifndef SQLITE_OMIT_LOAD_EXTENSION
SQLITE_PRIVATE void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
  return pVfs->xDlOpen(pVfs, zPath);
}
SQLITE_PRIVATE void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
  pVfs->xDlError(pVfs, nByte, zBufOut);
}
SQLITE_PRIVATE void (*sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHdle, const char *zSym))(void){
  return pVfs->xDlSym(pVfs, pHdle, zSym);
}
SQLITE_PRIVATE void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
  pVfs->xDlClose(pVfs, pHandle);
}
#endif /* SQLITE_OMIT_LOAD_EXTENSION */
SQLITE_PRIVATE int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
  return pVfs->xRandomness(pVfs, nByte, zBufOut);
}
SQLITE_PRIVATE int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
  return pVfs->xSleep(pVfs, nMicro);
}
SQLITE_PRIVATE int sqlite3OsCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){
  return pVfs->xCurrentTime(pVfs, pTimeOut);
}

SQLITE_PRIVATE int sqlite3OsOpenMalloc(
  sqlite3_vfs *pVfs,
  const char *zFile,
  sqlite3_file **ppFile,
  int flags,
  int *pOutFlags
){
  int rc = SQLITE_NOMEM;
  sqlite3_file *pFile;
  pFile = (sqlite3_file *)sqlite3Malloc(pVfs->szOsFile);
  if( pFile ){
    rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, pOutFlags);
    if( rc!=SQLITE_OK ){
      sqlite3_free(pFile);
    }else{
      *ppFile = pFile;
    }
  }
  return rc;
}
SQLITE_PRIVATE int sqlite3OsCloseFree(sqlite3_file *pFile){
  int rc = SQLITE_OK;
  assert( pFile );
  rc = sqlite3OsClose(pFile);
  sqlite3_free(pFile);
  return rc;
}

/*
** This function is a wrapper around the OS specific implementation of
** sqlite3_os_init(). The purpose of the wrapper is to provide the
** ability to simulate a malloc failure, so that the handling of an
** error in sqlite3_os_init() by the upper layers can be tested.
*/
SQLITE_PRIVATE int sqlite3OsInit(void){
  void *p = sqlite3_malloc(10);
  if( p==0 ) return SQLITE_NOMEM;
  sqlite3_free(p);
  return sqlite3_os_init();
}

/*
** The list of all registered VFS implementations.
*/
static sqlite3_vfs * SQLITE_WSD vfsList = 0;
#define vfsList GLOBAL(sqlite3_vfs *, vfsList)

/*
** Locate a VFS by name.  If no name is given, simply return the
** first VFS on the list.
*/
SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
  sqlite3_vfs *pVfs = 0;
#if SQLITE_THREADSAFE
  sqlite3_mutex *mutex;
#endif
#ifndef SQLITE_OMIT_AUTOINIT
  int rc = sqlite3_initialize();
  if( rc ) return 0;
#endif
#if SQLITE_THREADSAFE
  mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
#endif
  sqlite3_mutex_enter(mutex);
  for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){
    if( zVfs==0 ) break;
    if( strcmp(zVfs, pVfs->zName)==0 ) break;
  }
  sqlite3_mutex_leave(mutex);
  return pVfs;
}

/*
** Unlink a VFS from the linked list
*/
static void vfsUnlink(sqlite3_vfs *pVfs){
  assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) );
  if( pVfs==0 ){
    /* No-op */
  }else if( vfsList==pVfs ){
    vfsList = pVfs->pNext;
  }else if( vfsList ){
    sqlite3_vfs *p = vfsList;
    while( p->pNext && p->pNext!=pVfs ){
      p = p->pNext;
    }
    if( p->pNext==pVfs ){
      p->pNext = pVfs->pNext;
    }
  }
}

/*
** Register a VFS with the system.  It is harmless to register the same
** VFS multiple times.  The new VFS becomes the default if makeDflt is
** true.
*/
SQLITE_API int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
  sqlite3_mutex *mutex = 0;
#ifndef SQLITE_OMIT_AUTOINIT
  int rc = sqlite3_initialize();
  if( rc ) return rc;
#endif
  mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(mutex);
  vfsUnlink(pVfs);
  if( makeDflt || vfsList==0 ){
    pVfs->pNext = vfsList;
    vfsList = pVfs;
  }else{
    pVfs->pNext = vfsList->pNext;
    vfsList->pNext = pVfs;
  }
  assert(vfsList);
  sqlite3_mutex_leave(mutex);
  return SQLITE_OK;
}

/*
** Unregister a VFS so that it is no longer accessible.
*/
SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
#if SQLITE_THREADSAFE
  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
#endif
  sqlite3_mutex_enter(mutex);
  vfsUnlink(pVfs);
  sqlite3_mutex_leave(mutex);
  return SQLITE_OK;
}

/************** End of os.c **************************************************/
/************** Begin file fault.c *******************************************/
/*
** 2008 Jan 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains code to support the concept of "benign"
** malloc failures (when the xMalloc() or xRealloc() method of the
** sqlite3_mem_methods structure fails to allocate a block of memory
** and returns 0).
**
** Most malloc failures are non-benign. After they occur, SQLite
** abandons the current operation and returns an error code (usually
** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily
** fatal. For example, if a malloc fails while resizing a hash table, this
** is completely recoverable simply by not carrying out the resize. The
** hash table will continue to function normally.  So a malloc failure
** during a hash table resize is a benign fault.
*/


#ifndef SQLITE_OMIT_BUILTIN_TEST

/*
** Global variables.
*/
typedef struct BenignMallocHooks BenignMallocHooks;
static SQLITE_WSD struct BenignMallocHooks {
  void (*xBenignBegin)(void);
  void (*xBenignEnd)(void);
} sqlite3Hooks = { 0, 0 };

/* The "wsdHooks" macro will resolve to the appropriate BenignMallocHooks
** structure.  If writable static data is unsupported on the target,
** we have to locate the state vector at run-time.  In the more common
** case where writable static data is supported, wsdHooks can refer directly
** to the "sqlite3Hooks" state vector declared above.
*/
#ifdef SQLITE_OMIT_WSD
# define wsdHooksInit \
  BenignMallocHooks *x = &GLOBAL(BenignMallocHooks,sqlite3Hooks)
# define wsdHooks x[0]
#else
# define wsdHooksInit
# define wsdHooks sqlite3Hooks
#endif


/*
** Register hooks to call when sqlite3BeginBenignMalloc() and
** sqlite3EndBenignMalloc() are called, respectively.
*/
SQLITE_PRIVATE void sqlite3BenignMallocHooks(
  void (*xBenignBegin)(void),
  void (*xBenignEnd)(void)
){
  wsdHooksInit;
  wsdHooks.xBenignBegin = xBenignBegin;
  wsdHooks.xBenignEnd = xBenignEnd;
}

/*
** This (sqlite3EndBenignMalloc()) is called by SQLite code to indicate that
** subsequent malloc failures are benign. A call to sqlite3EndBenignMalloc()
** indicates that subsequent malloc failures are non-benign.
*/
SQLITE_PRIVATE void sqlite3BeginBenignMalloc(void){
  wsdHooksInit;
  if( wsdHooks.xBenignBegin ){
    wsdHooks.xBenignBegin();
  }
}
SQLITE_PRIVATE void sqlite3EndBenignMalloc(void){
  wsdHooksInit;
  if( wsdHooks.xBenignEnd ){
    wsdHooks.xBenignEnd();
  }
}

#endif   /* #ifndef SQLITE_OMIT_BUILTIN_TEST */

/************** End of fault.c ***********************************************/
/************** Begin file mem0.c ********************************************/
/*
** 2008 October 28
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains a no-op memory allocation drivers for use when
** SQLITE_ZERO_MALLOC is defined.  The allocation drivers implemented
** here always fail.  SQLite will not operate with these drivers.  These
** are merely placeholders.  Real drivers must be substituted using
** sqlite3_config() before SQLite will operate.
*/

/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/
#ifdef SQLITE_ZERO_MALLOC

/*
** No-op versions of all memory allocation routines
*/
static void *sqlite3MemMalloc(int nByte){ return 0; }
static void sqlite3MemFree(void *pPrior){ return; }
static void *sqlite3MemRealloc(void *pPrior, int nByte){ return 0; }
static int sqlite3MemSize(void *pPrior){ return 0; }
static int sqlite3MemRoundup(int n){ return n; }
static int sqlite3MemInit(void *NotUsed){ return SQLITE_OK; }
static void sqlite3MemShutdown(void *NotUsed){ return; }

/*
** This routine is the only routine in this file with external linkage.
**
** Populate the low-level memory allocation function pointers in
** sqlite3GlobalConfig.m with pointers to the routines in this file.
*/
SQLITE_PRIVATE void sqlite3MemSetDefault(void){
  static const sqlite3_mem_methods defaultMethods = {
     sqlite3MemMalloc,
     sqlite3MemFree,
     sqlite3MemRealloc,
     sqlite3MemSize,
     sqlite3MemRoundup,
     sqlite3MemInit,
     sqlite3MemShutdown,
     0
  };
  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
}

#endif /* SQLITE_ZERO_MALLOC */

/************** End of mem0.c ************************************************/
/************** Begin file mem1.c ********************************************/
/*
** 2007 August 14
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains low-level memory allocation drivers for when
** SQLite will use the standard C-library malloc/realloc/free interface
** to obtain the memory it needs.
**
** This file contains implementations of the low-level memory allocation
** routines specified in the sqlite3_mem_methods object.
*/

/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/
#ifdef SQLITE_SYSTEM_MALLOC

/*
** Like malloc(), but remember the size of the allocation
** so that we can find it later using sqlite3MemSize().
**
** For this low-level routine, we are guaranteed that nByte>0 because
** cases of nByte<=0 will be intercepted and dealt with by higher level
** routines.
*/
static void *sqlite3MemMalloc(int nByte){
  sqlite3_int64 *p;
  assert( nByte>0 );
  nByte = ROUND8(nByte);
  p = malloc( nByte+8 );
  if( p ){
    p[0] = nByte;
    p++;
  }else{
    testcase( sqlite3GlobalConfig.xLog!=0 );
    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes of memory", nByte);
  }
  return (void *)p;
}

/*
** Like free() but works for allocations obtained from sqlite3MemMalloc()
** or sqlite3MemRealloc().
**
** For this low-level routine, we already know that pPrior!=0 since
** cases where pPrior==0 will have been intecepted and dealt with
** by higher-level routines.
*/
static void sqlite3MemFree(void *pPrior){
  sqlite3_int64 *p = (sqlite3_int64*)pPrior;
  assert( pPrior!=0 );
  p--;
  free(p);
}

/*
** Report the allocated size of a prior return from xMalloc()
** or xRealloc().
*/
static int sqlite3MemSize(void *pPrior){
  sqlite3_int64 *p;
  if( pPrior==0 ) return 0;
  p = (sqlite3_int64*)pPrior;
  p--;
  return (int)p[0];
}

/*
** Like realloc().  Resize an allocation previously obtained from
** sqlite3MemMalloc().
**
** For this low-level interface, we know that pPrior!=0.  Cases where
** pPrior==0 while have been intercepted by higher-level routine and
** redirected to xMalloc.  Similarly, we know that nByte>0 becauses
** cases where nByte<=0 will have been intercepted by higher-level
** routines and redirected to xFree.
*/
static void *sqlite3MemRealloc(void *pPrior, int nByte){
  sqlite3_int64 *p = (sqlite3_int64*)pPrior;
  assert( pPrior!=0 && nByte>0 );
  nByte = ROUND8(nByte);
  p = (sqlite3_int64*)pPrior;
  p--;
  p = realloc(p, nByte+8 );
  if( p ){
    p[0] = nByte;
    p++;
  }else{
    testcase( sqlite3GlobalConfig.xLog!=0 );
    sqlite3_log(SQLITE_NOMEM,
      "failed memory resize %u to %u bytes",
      sqlite3MemSize(pPrior), nByte);
  }
  return (void*)p;
}

/*
** Round up a request size to the next valid allocation size.
*/
static int sqlite3MemRoundup(int n){
  return ROUND8(n);
}

/*
** Initialize this module.
*/
static int sqlite3MemInit(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return SQLITE_OK;
}

/*
** Deinitialize this module.
*/
static void sqlite3MemShutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return;
}

/*
** This routine is the only routine in this file with external linkage.
**
** Populate the low-level memory allocation function pointers in
** sqlite3GlobalConfig.m with pointers to the routines in this file.
*/
SQLITE_PRIVATE void sqlite3MemSetDefault(void){
  static const sqlite3_mem_methods defaultMethods = {
     sqlite3MemMalloc,
     sqlite3MemFree,
     sqlite3MemRealloc,
     sqlite3MemSize,
     sqlite3MemRoundup,
     sqlite3MemInit,
     sqlite3MemShutdown,
     0
  };
  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
}

#endif /* SQLITE_SYSTEM_MALLOC */

/************** End of mem1.c ************************************************/
/************** Begin file mem2.c ********************************************/
/*
** 2007 August 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains low-level memory allocation drivers for when
** SQLite will use the standard C-library malloc/realloc/free interface
** to obtain the memory it needs while adding lots of additional debugging
** information to each allocation in order to help detect and fix memory
** leaks and memory usage errors.
**
** This file contains implementations of the low-level memory allocation
** routines specified in the sqlite3_mem_methods object.
*/

/*
** This version of the memory allocator is used only if the
** SQLITE_MEMDEBUG macro is defined
*/
#ifdef SQLITE_MEMDEBUG

/*
** The backtrace functionality is only available with GLIBC
*/
#ifdef __GLIBC__
  extern int backtrace(void**,int);
  extern void backtrace_symbols_fd(void*const*,int,int);
#else
# define backtrace(A,B) 1
# define backtrace_symbols_fd(A,B,C)
#endif

/*
** Each memory allocation looks like this:
**
**  ------------------------------------------------------------------------
**  | Title |  backtrace pointers |  MemBlockHdr |  allocation |  EndGuard |
**  ------------------------------------------------------------------------
**
** The application code sees only a pointer to the allocation.  We have
** to back up from the allocation pointer to find the MemBlockHdr.  The
** MemBlockHdr tells us the size of the allocation and the number of
** backtrace pointers.  There is also a guard word at the end of the
** MemBlockHdr.
*/
struct MemBlockHdr {
  i64 iSize;                          /* Size of this allocation */
  struct MemBlockHdr *pNext, *pPrev;  /* Linked list of all unfreed memory */
  char nBacktrace;                    /* Number of backtraces on this alloc */
  char nBacktraceSlots;               /* Available backtrace slots */
  short nTitle;                       /* Bytes of title; includes '\0' */
  int iForeGuard;                     /* Guard word for sanity */
};

/*
** Guard words
*/
#define FOREGUARD 0x80F5E153
#define REARGUARD 0xE4676B53

/*
** Number of malloc size increments to track.
*/
#define NCSIZE  1000

/*
** All of the static variables used by this module are collected
** into a single structure named "mem".  This is to keep the
** static variables organized and to reduce namespace pollution
** when this module is combined with other in the amalgamation.
*/
static struct {

  /*
  ** Mutex to control access to the memory allocation subsystem.
  */
  sqlite3_mutex *mutex;

  /*
  ** Head and tail of a linked list of all outstanding allocations
  */
  struct MemBlockHdr *pFirst;
  struct MemBlockHdr *pLast;

  /*
  ** The number of levels of backtrace to save in new allocations.
  */
  int nBacktrace;
  void (*xBacktrace)(int, int, void **);

  /*
  ** Title text to insert in front of each block
  */
  int nTitle;        /* Bytes of zTitle to save.  Includes '\0' and padding */
  char zTitle[100];  /* The title text */

  /*
  ** sqlite3MallocDisallow() increments the following counter.
  ** sqlite3MallocAllow() decrements it.
  */
  int disallow; /* Do not allow memory allocation */

  /*
  ** Gather statistics on the sizes of memory allocations.
  ** nAlloc[i] is the number of allocation attempts of i*8
  ** bytes.  i==NCSIZE is the number of allocation attempts for
  ** sizes more than NCSIZE*8 bytes.
  */
  int nAlloc[NCSIZE];      /* Total number of allocations */
  int nCurrent[NCSIZE];    /* Current number of allocations */
  int mxCurrent[NCSIZE];   /* Highwater mark for nCurrent */

} mem;


/*
** Adjust memory usage statistics
*/
static void adjustStats(int iSize, int increment){
  int i = ROUND8(iSize)/8;
  if( i>NCSIZE-1 ){
    i = NCSIZE - 1;
  }
  if( increment>0 ){
    mem.nAlloc[i]++;
    mem.nCurrent[i]++;
    if( mem.nCurrent[i]>mem.mxCurrent[i] ){
      mem.mxCurrent[i] = mem.nCurrent[i];
    }
  }else{
    mem.nCurrent[i]--;
    assert( mem.nCurrent[i]>=0 );
  }
}

/*
** Given an allocation, find the MemBlockHdr for that allocation.
**
** This routine checks the guards at either end of the allocation and
** if they are incorrect it asserts.
*/
static struct MemBlockHdr *sqlite3MemsysGetHeader(void *pAllocation){
  struct MemBlockHdr *p;
  int *pInt;
  u8 *pU8;
  int nReserve;

  p = (struct MemBlockHdr*)pAllocation;
  p--;
  assert( p->iForeGuard==(int)FOREGUARD );
  nReserve = ROUND8(p->iSize);
  pInt = (int*)pAllocation;
  pU8 = (u8*)pAllocation;
  assert( pInt[nReserve/sizeof(int)]==(int)REARGUARD );
  /* This checks any of the "extra" bytes allocated due
  ** to rounding up to an 8 byte boundary to ensure
  ** they haven't been overwritten.
  */
  while( nReserve-- > p->iSize ) assert( pU8[nReserve]==0x65 );
  return p;
}

/*
** Return the number of bytes currently allocated at address p.
*/
static int sqlite3MemSize(void *p){
  struct MemBlockHdr *pHdr;
  if( !p ){
    return 0;
  }
  pHdr = sqlite3MemsysGetHeader(p);
  return pHdr->iSize;
}

/*
** Initialize the memory allocation subsystem.
*/
static int sqlite3MemInit(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  assert( (sizeof(struct MemBlockHdr)&7) == 0 );
  if( !sqlite3GlobalConfig.bMemstat ){
    /* If memory status is enabled, then the malloc.c wrapper will already
    ** hold the STATIC_MEM mutex when the routines here are invoked. */
    mem.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
  }
  return SQLITE_OK;
}

/*
** Deinitialize the memory allocation subsystem.
*/
static void sqlite3MemShutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  mem.mutex = 0;
}

/*
** Round up a request size to the next valid allocation size.
*/
static int sqlite3MemRoundup(int n){
  return ROUND8(n);
}

/*
** Fill a buffer with pseudo-random bytes.  This is used to preset
** the content of a new memory allocation to unpredictable values and
** to clear the content of a freed allocation to unpredictable values.
*/
static void randomFill(char *pBuf, int nByte){
  unsigned int x, y, r;
  x = SQLITE_PTR_TO_INT(pBuf);
  y = nByte | 1;
  while( nByte >= 4 ){
    x = (x>>1) ^ (-(x&1) & 0xd0000001);
    y = y*1103515245 + 12345;
    r = x ^ y;
    *(int*)pBuf = r;
    pBuf += 4;
    nByte -= 4;
  }
  while( nByte-- > 0 ){
    x = (x>>1) ^ (-(x&1) & 0xd0000001);
    y = y*1103515245 + 12345;
    r = x ^ y;
    *(pBuf++) = r & 0xff;
  }
}

/*
** Allocate nByte bytes of memory.
*/
static void *sqlite3MemMalloc(int nByte){
  struct MemBlockHdr *pHdr;
  void **pBt;
  char *z;
  int *pInt;
  void *p = 0;
  int totalSize;
  int nReserve;
  sqlite3_mutex_enter(mem.mutex);
  assert( mem.disallow==0 );
  nReserve = ROUND8(nByte);
  totalSize = nReserve + sizeof(*pHdr) + sizeof(int) +
               mem.nBacktrace*sizeof(void*) + mem.nTitle;
  p = malloc(totalSize);
  if( p ){
    z = p;
    pBt = (void**)&z[mem.nTitle];
    pHdr = (struct MemBlockHdr*)&pBt[mem.nBacktrace];
    pHdr->pNext = 0;
    pHdr->pPrev = mem.pLast;
    if( mem.pLast ){
      mem.pLast->pNext = pHdr;
    }else{
      mem.pFirst = pHdr;
    }
    mem.pLast = pHdr;
    pHdr->iForeGuard = FOREGUARD;
    pHdr->nBacktraceSlots = mem.nBacktrace;
    pHdr->nTitle = mem.nTitle;
    if( mem.nBacktrace ){
      void *aAddr[40];
      pHdr->nBacktrace = backtrace(aAddr, mem.nBacktrace+1)-1;
      memcpy(pBt, &aAddr[1], pHdr->nBacktrace*sizeof(void*));
      assert(pBt[0]);
      if( mem.xBacktrace ){
        mem.xBacktrace(nByte, pHdr->nBacktrace-1, &aAddr[1]);
      }
    }else{
      pHdr->nBacktrace = 0;
    }
    if( mem.nTitle ){
      memcpy(z, mem.zTitle, mem.nTitle);
    }
    pHdr->iSize = nByte;
    adjustStats(nByte, +1);
    pInt = (int*)&pHdr[1];
    pInt[nReserve/sizeof(int)] = REARGUARD;
    randomFill((char*)pInt, nByte);
    memset(((char*)pInt)+nByte, 0x65, nReserve-nByte);
    p = (void*)pInt;
  }
  sqlite3_mutex_leave(mem.mutex);
  return p;
}

/*
** Free memory.
*/
static void sqlite3MemFree(void *pPrior){
  struct MemBlockHdr *pHdr;
  void **pBt;
  char *z;
  assert( sqlite3GlobalConfig.bMemstat || mem.mutex!=0 );
  pHdr = sqlite3MemsysGetHeader(pPrior);
  pBt = (void**)pHdr;
  pBt -= pHdr->nBacktraceSlots;
  sqlite3_mutex_enter(mem.mutex);
  if( pHdr->pPrev ){
    assert( pHdr->pPrev->pNext==pHdr );
    pHdr->pPrev->pNext = pHdr->pNext;
  }else{
    assert( mem.pFirst==pHdr );
    mem.pFirst = pHdr->pNext;
  }
  if( pHdr->pNext ){
    assert( pHdr->pNext->pPrev==pHdr );
    pHdr->pNext->pPrev = pHdr->pPrev;
  }else{
    assert( mem.pLast==pHdr );
    mem.pLast = pHdr->pPrev;
  }
  z = (char*)pBt;
  z -= pHdr->nTitle;
  adjustStats(pHdr->iSize, -1);
  randomFill(z, sizeof(void*)*pHdr->nBacktraceSlots + sizeof(*pHdr) +
                pHdr->iSize + sizeof(int) + pHdr->nTitle);
  free(z);
  sqlite3_mutex_leave(mem.mutex);
}

/*
** Change the size of an existing memory allocation.
**
** For this debugging implementation, we *always* make a copy of the
** allocation into a new place in memory.  In this way, if the
** higher level code is using pointer to the old allocation, it is
** much more likely to break and we are much more liking to find
** the error.
*/
static void *sqlite3MemRealloc(void *pPrior, int nByte){
  struct MemBlockHdr *pOldHdr;
  void *pNew;
  assert( mem.disallow==0 );
  pOldHdr = sqlite3MemsysGetHeader(pPrior);
  pNew = sqlite3MemMalloc(nByte);
  if( pNew ){
    memcpy(pNew, pPrior, nByte<pOldHdr->iSize ? nByte : pOldHdr->iSize);
    if( nByte>pOldHdr->iSize ){
      randomFill(&((char*)pNew)[pOldHdr->iSize], nByte - pOldHdr->iSize);
    }
    sqlite3MemFree(pPrior);
  }
  return pNew;
}

/*
** Populate the low-level memory allocation function pointers in
** sqlite3GlobalConfig.m with pointers to the routines in this file.
*/
SQLITE_PRIVATE void sqlite3MemSetDefault(void){
  static const sqlite3_mem_methods defaultMethods = {
     sqlite3MemMalloc,
     sqlite3MemFree,
     sqlite3MemRealloc,
     sqlite3MemSize,
     sqlite3MemRoundup,
     sqlite3MemInit,
     sqlite3MemShutdown,
     0
  };
  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
}

/*
** Set the number of backtrace levels kept for each allocation.
** A value of zero turns off backtracing.  The number is always rounded
** up to a multiple of 2.
*/
SQLITE_PRIVATE void sqlite3MemdebugBacktrace(int depth){
  if( depth<0 ){ depth = 0; }
  if( depth>20 ){ depth = 20; }
  depth = (depth+1)&0xfe;
  mem.nBacktrace = depth;
}

SQLITE_PRIVATE void sqlite3MemdebugBacktraceCallback(void (*xBacktrace)(int, int, void **)){
  mem.xBacktrace = xBacktrace;
}

/*
** Set the title string for subsequent allocations.
*/
SQLITE_PRIVATE void sqlite3MemdebugSettitle(const char *zTitle){
  unsigned int n = sqlite3Strlen30(zTitle) + 1;
  sqlite3_mutex_enter(mem.mutex);
  if( n>=sizeof(mem.zTitle) ) n = sizeof(mem.zTitle)-1;
  memcpy(mem.zTitle, zTitle, n);
  mem.zTitle[n] = 0;
  mem.nTitle = ROUND8(n);
  sqlite3_mutex_leave(mem.mutex);
}

SQLITE_PRIVATE void sqlite3MemdebugSync(){
  struct MemBlockHdr *pHdr;
  for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
    void **pBt = (void**)pHdr;
    pBt -= pHdr->nBacktraceSlots;
    mem.xBacktrace(pHdr->iSize, pHdr->nBacktrace-1, &pBt[1]);
  }
}

/*
** Open the file indicated and write a log of all unfreed memory
** allocations into that log.
*/
SQLITE_PRIVATE void sqlite3MemdebugDump(const char *zFilename){
  FILE *out;
  struct MemBlockHdr *pHdr;
  void **pBt;
  int i;
  out = fopen(zFilename, "w");
  if( out==0 ){
    fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
                    zFilename);
    return;
  }
  for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
    char *z = (char*)pHdr;
    z -= pHdr->nBacktraceSlots*sizeof(void*) + pHdr->nTitle;
    fprintf(out, "**** %lld bytes at %p from %s ****\n",
            pHdr->iSize, &pHdr[1], pHdr->nTitle ? z : "???");
    if( pHdr->nBacktrace ){
      fflush(out);
      pBt = (void**)pHdr;
      pBt -= pHdr->nBacktraceSlots;
      backtrace_symbols_fd(pBt, pHdr->nBacktrace, fileno(out));
      fprintf(out, "\n");
    }
  }
  fprintf(out, "COUNTS:\n");
  for(i=0; i<NCSIZE-1; i++){
    if( mem.nAlloc[i] ){
      fprintf(out, "   %5d: %10d %10d %10d\n",
            i*8, mem.nAlloc[i], mem.nCurrent[i], mem.mxCurrent[i]);
    }
  }
  if( mem.nAlloc[NCSIZE-1] ){
    fprintf(out, "   %5d: %10d %10d %10d\n",
             NCSIZE*8-8, mem.nAlloc[NCSIZE-1],
             mem.nCurrent[NCSIZE-1], mem.mxCurrent[NCSIZE-1]);
  }
  fclose(out);
}

/*
** Return the number of times sqlite3MemMalloc() has been called.
*/
SQLITE_PRIVATE int sqlite3MemdebugMallocCount(){
  int i;
  int nTotal = 0;
  for(i=0; i<NCSIZE; i++){
    nTotal += mem.nAlloc[i];
  }
  return nTotal;
}


#endif /* SQLITE_MEMDEBUG */

/************** End of mem2.c ************************************************/
/************** Begin file mem3.c ********************************************/
/*
** 2007 October 14
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.
**
** This version of the memory allocation subsystem omits all
** use of malloc(). The SQLite user supplies a block of memory
** before calling sqlite3_initialize() from which allocations
** are made and returned by the xMalloc() and xRealloc()
** implementations. Once sqlite3_initialize() has been called,
** the amount of memory available to SQLite is fixed and cannot
** be changed.
**
** This version of the memory allocation subsystem is included
** in the build only if SQLITE_ENABLE_MEMSYS3 is defined.
*/

/*
** This version of the memory allocator is only built into the library
** SQLITE_ENABLE_MEMSYS3 is defined. Defining this symbol does not
** mean that the library will use a memory-pool by default, just that
** it is available. The mempool allocator is activated by calling
** sqlite3_config().
*/
#ifdef SQLITE_ENABLE_MEMSYS3

/*
** Maximum size (in Mem3Blocks) of a "small" chunk.
*/
#define MX_SMALL 10


/*
** Number of freelist hash slots
*/
#define N_HASH  61

/*
** A memory allocation (also called a "chunk") consists of two or
** more blocks where each block is 8 bytes.  The first 8 bytes are
** a header that is not returned to the user.
**
** A chunk is two or more blocks that is either checked out or
** free.  The first block has format u.hdr.  u.hdr.size4x is 4 times the
** size of the allocation in blocks if the allocation is free.
** The u.hdr.size4x&1 bit is true if the chunk is checked out and
** false if the chunk is on the freelist.  The u.hdr.size4x&2 bit
** is true if the previous chunk is checked out and false if the
** previous chunk is free.  The u.hdr.prevSize field is the size of
** the previous chunk in blocks if the previous chunk is on the
** freelist. If the previous chunk is checked out, then
** u.hdr.prevSize can be part of the data for that chunk and should
** not be read or written.
**
** We often identify a chunk by its index in mem3.aPool[].  When
** this is done, the chunk index refers to the second block of
** the chunk.  In this way, the first chunk has an index of 1.
** A chunk index of 0 means "no such chunk" and is the equivalent
** of a NULL pointer.
**
** The second block of free chunks is of the form u.list.  The
** two fields form a double-linked list of chunks of related sizes.
** Pointers to the head of the list are stored in mem3.aiSmall[]
** for smaller chunks and mem3.aiHash[] for larger chunks.
**
** The second block of a chunk is user data if the chunk is checked
** out.  If a chunk is checked out, the user data may extend into
** the u.hdr.prevSize value of the following chunk.
*/
typedef struct Mem3Block Mem3Block;
struct Mem3Block {
  union {
    struct {
      u32 prevSize;   /* Size of previous chunk in Mem3Block elements */
      u32 size4x;     /* 4x the size of current chunk in Mem3Block elements */
    } hdr;
    struct {
      u32 next;       /* Index in mem3.aPool[] of next free chunk */
      u32 prev;       /* Index in mem3.aPool[] of previous free chunk */
    } list;
  } u;
};

/*
** All of the static variables used by this module are collected
** into a single structure named "mem3".  This is to keep the
** static variables organized and to reduce namespace pollution
** when this module is combined with other in the amalgamation.
*/
static SQLITE_WSD struct Mem3Global {
  /*
  ** Memory available for allocation. nPool is the size of the array
  ** (in Mem3Blocks) pointed to by aPool less 2.
  */
  u32 nPool;
  Mem3Block *aPool;

  /*
  ** True if we are evaluating an out-of-memory callback.
  */
  int alarmBusy;

  /*
  ** Mutex to control access to the memory allocation subsystem.
  */
  sqlite3_mutex *mutex;

  /*
  ** The minimum amount of free space that we have seen.
  */
  u32 mnMaster;

  /*
  ** iMaster is the index of the master chunk.  Most new allocations
  ** occur off of this chunk.  szMaster is the size (in Mem3Blocks)
  ** of the current master.  iMaster is 0 if there is not master chunk.
  ** The master chunk is not in either the aiHash[] or aiSmall[].
  */
  u32 iMaster;
  u32 szMaster;

  /*
  ** Array of lists of free blocks according to the block size
  ** for smaller chunks, or a hash on the block size for larger
  ** chunks.
  */
  u32 aiSmall[MX_SMALL-1];   /* For sizes 2 through MX_SMALL, inclusive */
  u32 aiHash[N_HASH];        /* For sizes MX_SMALL+1 and larger */
} mem3 = { 97535575 };

#define mem3 GLOBAL(struct Mem3Global, mem3)

/*
** Unlink the chunk at mem3.aPool[i] from list it is currently
** on.  *pRoot is the list that i is a member of.
*/
static void memsys3UnlinkFromList(u32 i, u32 *pRoot){
  u32 next = mem3.aPool[i].u.list.next;
  u32 prev = mem3.aPool[i].u.list.prev;
  assert( sqlite3_mutex_held(mem3.mutex) );
  if( prev==0 ){
    *pRoot = next;
  }else{
    mem3.aPool[prev].u.list.next = next;
  }
  if( next ){
    mem3.aPool[next].u.list.prev = prev;
  }
  mem3.aPool[i].u.list.next = 0;
  mem3.aPool[i].u.list.prev = 0;
}

/*
** Unlink the chunk at index i from
** whatever list is currently a member of.
*/
static void memsys3Unlink(u32 i){
  u32 size, hash;
  assert( sqlite3_mutex_held(mem3.mutex) );
  assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 );
  assert( i>=1 );
  size = mem3.aPool[i-1].u.hdr.size4x/4;
  assert( size==mem3.aPool[i+size-1].u.hdr.prevSize );
  assert( size>=2 );
  if( size <= MX_SMALL ){
    memsys3UnlinkFromList(i, &mem3.aiSmall[size-2]);
  }else{
    hash = size % N_HASH;
    memsys3UnlinkFromList(i, &mem3.aiHash[hash]);
  }
}

/*
** Link the chunk at mem3.aPool[i] so that is on the list rooted
** at *pRoot.
*/
static void memsys3LinkIntoList(u32 i, u32 *pRoot){
  assert( sqlite3_mutex_held(mem3.mutex) );
  mem3.aPool[i].u.list.next = *pRoot;
  mem3.aPool[i].u.list.prev = 0;
  if( *pRoot ){
    mem3.aPool[*pRoot].u.list.prev = i;
  }
  *pRoot = i;
}

/*
** Link the chunk at index i into either the appropriate
** small chunk list, or into the large chunk hash table.
*/
static void memsys3Link(u32 i){
  u32 size, hash;
  assert( sqlite3_mutex_held(mem3.mutex) );
  assert( i>=1 );
  assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 );
  size = mem3.aPool[i-1].u.hdr.size4x/4;
  assert( size==mem3.aPool[i+size-1].u.hdr.prevSize );
  assert( size>=2 );
  if( size <= MX_SMALL ){
    memsys3LinkIntoList(i, &mem3.aiSmall[size-2]);
  }else{
    hash = size % N_HASH;
    memsys3LinkIntoList(i, &mem3.aiHash[hash]);
  }
}

/*
** If the STATIC_MEM mutex is not already held, obtain it now. The mutex
** will already be held (obtained by code in malloc.c) if
** sqlite3GlobalConfig.bMemStat is true.
*/
static void memsys3Enter(void){
  if( sqlite3GlobalConfig.bMemstat==0 && mem3.mutex==0 ){
    mem3.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
  }
  sqlite3_mutex_enter(mem3.mutex);
}
static void memsys3Leave(void){
  sqlite3_mutex_leave(mem3.mutex);
}

/*
** Called when we are unable to satisfy an allocation of nBytes.
*/
static void memsys3OutOfMemory(int nByte){
  if( !mem3.alarmBusy ){
    mem3.alarmBusy = 1;
    assert( sqlite3_mutex_held(mem3.mutex) );
    sqlite3_mutex_leave(mem3.mutex);
    sqlite3_release_memory(nByte);
    sqlite3_mutex_enter(mem3.mutex);
    mem3.alarmBusy = 0;
  }
}


/*
** Chunk i is a free chunk that has been unlinked.  Adjust its
** size parameters for check-out and return a pointer to the
** user portion of the chunk.
*/
static void *memsys3Checkout(u32 i, u32 nBlock){
  u32 x;
  assert( sqlite3_mutex_held(mem3.mutex) );
  assert( i>=1 );
  assert( mem3.aPool[i-1].u.hdr.size4x/4==nBlock );
  assert( mem3.aPool[i+nBlock-1].u.hdr.prevSize==nBlock );
  x = mem3.aPool[i-1].u.hdr.size4x;
  mem3.aPool[i-1].u.hdr.size4x = nBlock*4 | 1 | (x&2);
  mem3.aPool[i+nBlock-1].u.hdr.prevSize = nBlock;
  mem3.aPool[i+nBlock-1].u.hdr.size4x |= 2;
  return &mem3.aPool[i];
}

/*
** Carve a piece off of the end of the mem3.iMaster free chunk.
** Return a pointer to the new allocation.  Or, if the master chunk
** is not large enough, return 0.
*/
static void *memsys3FromMaster(u32 nBlock){
  assert( sqlite3_mutex_held(mem3.mutex) );
  assert( mem3.szMaster>=nBlock );
  if( nBlock>=mem3.szMaster-1 ){
    /* Use the entire master */
    void *p = memsys3Checkout(mem3.iMaster, mem3.szMaster);
    mem3.iMaster = 0;
    mem3.szMaster = 0;
    mem3.mnMaster = 0;
    return p;
  }else{
    /* Split the master block.  Return the tail. */
    u32 newi, x;
    newi = mem3.iMaster + mem3.szMaster - nBlock;
    assert( newi > mem3.iMaster+1 );
    mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = nBlock;
    mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x |= 2;
    mem3.aPool[newi-1].u.hdr.size4x = nBlock*4 + 1;
    mem3.szMaster -= nBlock;
    mem3.aPool[newi-1].u.hdr.prevSize = mem3.szMaster;
    x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2;
    mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x;
    if( mem3.szMaster < mem3.mnMaster ){
      mem3.mnMaster = mem3.szMaster;
    }
    return (void*)&mem3.aPool[newi];
  }
}

/*
** *pRoot is the head of a list of free chunks of the same size
** or same size hash.  In other words, *pRoot is an entry in either
** mem3.aiSmall[] or mem3.aiHash[].
**
** This routine examines all entries on the given list and tries
** to coalesce each entries with adjacent free chunks.
**
** If it sees a chunk that is larger than mem3.iMaster, it replaces
** the current mem3.iMaster with the new larger chunk.  In order for
** this mem3.iMaster replacement to work, the master chunk must be
** linked into the hash tables.  That is not the normal state of
** affairs, of course.  The calling routine must link the master
** chunk before invoking this routine, then must unlink the (possibly
** changed) master chunk once this routine has finished.
*/
static void memsys3Merge(u32 *pRoot){
  u32 iNext, prev, size, i, x;

  assert( sqlite3_mutex_held(mem3.mutex) );
  for(i=*pRoot; i>0; i=iNext){
    iNext = mem3.aPool[i].u.list.next;
    size = mem3.aPool[i-1].u.hdr.size4x;
    assert( (size&1)==0 );
    if( (size&2)==0 ){
      memsys3UnlinkFromList(i, pRoot);
      assert( i > mem3.aPool[i-1].u.hdr.prevSize );
      prev = i - mem3.aPool[i-1].u.hdr.prevSize;
      if( prev==iNext ){
        iNext = mem3.aPool[prev].u.list.next;
      }
      memsys3Unlink(prev);
      size = i + size/4 - prev;
      x = mem3.aPool[prev-1].u.hdr.size4x & 2;
      mem3.aPool[prev-1].u.hdr.size4x = size*4 | x;
      mem3.aPool[prev+size-1].u.hdr.prevSize = size;
      memsys3Link(prev);
      i = prev;
    }else{
      size /= 4;
    }
    if( size>mem3.szMaster ){
      mem3.iMaster = i;
      mem3.szMaster = size;
    }
  }
}

/*
** Return a block of memory of at least nBytes in size.
** Return NULL if unable.
**
** This function assumes that the necessary mutexes, if any, are
** already held by the caller. Hence "Unsafe".
*/
static void *memsys3MallocUnsafe(int nByte){
  u32 i;
  u32 nBlock;
  u32 toFree;

  assert( sqlite3_mutex_held(mem3.mutex) );
  assert( sizeof(Mem3Block)==8 );
  if( nByte<=12 ){
    nBlock = 2;
  }else{
    nBlock = (nByte + 11)/8;
  }
  assert( nBlock>=2 );

  /* STEP 1:
  ** Look for an entry of the correct size in either the small
  ** chunk table or in the large chunk hash table.  This is
  ** successful most of the time (about 9 times out of 10).
  */
  if( nBlock <= MX_SMALL ){
    i = mem3.aiSmall[nBlock-2];
    if( i>0 ){
      memsys3UnlinkFromList(i, &mem3.aiSmall[nBlock-2]);
      return memsys3Checkout(i, nBlock);
    }
  }else{
    int hash = nBlock % N_HASH;
    for(i=mem3.aiHash[hash]; i>0; i=mem3.aPool[i].u.list.next){
      if( mem3.aPool[i-1].u.hdr.size4x/4==nBlock ){
        memsys3UnlinkFromList(i, &mem3.aiHash[hash]);
        return memsys3Checkout(i, nBlock);
      }
    }
  }

  /* STEP 2:
  ** Try to satisfy the allocation by carving a piece off of the end
  ** of the master chunk.  This step usually works if step 1 fails.
  */
  if( mem3.szMaster>=nBlock ){
    return memsys3FromMaster(nBlock);
  }


  /* STEP 3:
  ** Loop through the entire memory pool.  Coalesce adjacent free
  ** chunks.  Recompute the master chunk as the largest free chunk.
  ** Then try again to satisfy the allocation by carving a piece off
  ** of the end of the master chunk.  This step happens very
  ** rarely (we hope!)
  */
  for(toFree=nBlock*16; toFree<(mem3.nPool*16); toFree *= 2){
    memsys3OutOfMemory(toFree);
    if( mem3.iMaster ){
      memsys3Link(mem3.iMaster);
      mem3.iMaster = 0;
      mem3.szMaster = 0;
    }
    for(i=0; i<N_HASH; i++){
      memsys3Merge(&mem3.aiHash[i]);
    }
    for(i=0; i<MX_SMALL-1; i++){
      memsys3Merge(&mem3.aiSmall[i]);
    }
    if( mem3.szMaster ){
      memsys3Unlink(mem3.iMaster);
      if( mem3.szMaster>=nBlock ){
        return memsys3FromMaster(nBlock);
      }
    }
  }

  /* If none of the above worked, then we fail. */
  return 0;
}

/*
** Free an outstanding memory allocation.
**
** This function assumes that the necessary mutexes, if any, are
** already held by the caller. Hence "Unsafe".
*/
void memsys3FreeUnsafe(void *pOld){
  Mem3Block *p = (Mem3Block*)pOld;
  int i;
  u32 size, x;
  assert( sqlite3_mutex_held(mem3.mutex) );
  assert( p>mem3.aPool && p<&mem3.aPool[mem3.nPool] );
  i = p - mem3.aPool;
  assert( (mem3.aPool[i-1].u.hdr.size4x&1)==1 );
  size = mem3.aPool[i-1].u.hdr.size4x/4;
  assert( i+size<=mem3.nPool+1 );
  mem3.aPool[i-1].u.hdr.size4x &= ~1;
  mem3.aPool[i+size-1].u.hdr.prevSize = size;
  mem3.aPool[i+size-1].u.hdr.size4x &= ~2;
  memsys3Link(i);

  /* Try to expand the master using the newly freed chunk */
  if( mem3.iMaster ){
    while( (mem3.aPool[mem3.iMaster-1].u.hdr.size4x&2)==0 ){
      size = mem3.aPool[mem3.iMaster-1].u.hdr.prevSize;
      mem3.iMaster -= size;
      mem3.szMaster += size;
      memsys3Unlink(mem3.iMaster);
      x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2;
      mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x;
      mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = mem3.szMaster;
    }
    x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2;
    while( (mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x&1)==0 ){
      memsys3Unlink(mem3.iMaster+mem3.szMaster);
      mem3.szMaster += mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x/4;
      mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x;
      mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = mem3.szMaster;
    }
  }
}

/*
** Return the size of an outstanding allocation, in bytes.  The
** size returned omits the 8-byte header overhead.  This only
** works for chunks that are currently checked out.
*/
static int memsys3Size(void *p){
  Mem3Block *pBlock;
  if( p==0 ) return 0;
  pBlock = (Mem3Block*)p;
  assert( (pBlock[-1].u.hdr.size4x&1)!=0 );
  return (pBlock[-1].u.hdr.size4x&~3)*2 - 4;
}

/*
** Round up a request size to the next valid allocation size.
*/
static int memsys3Roundup(int n){
  if( n<=12 ){
    return 12;
  }else{
    return ((n+11)&~7) - 4;
  }
}

/*
** Allocate nBytes of memory.
*/
static void *memsys3Malloc(int nBytes){
  sqlite3_int64 *p;
  assert( nBytes>0 );          /* malloc.c filters out 0 byte requests */
  memsys3Enter();
  p = memsys3MallocUnsafe(nBytes);
  memsys3Leave();
  return (void*)p;
}

/*
** Free memory.
*/
void memsys3Free(void *pPrior){
  assert( pPrior );
  memsys3Enter();
  memsys3FreeUnsafe(pPrior);
  memsys3Leave();
}

/*
** Change the size of an existing memory allocation
*/
void *memsys3Realloc(void *pPrior, int nBytes){
  int nOld;
  void *p;
  if( pPrior==0 ){
    return sqlite3_malloc(nBytes);
  }
  if( nBytes<=0 ){
    sqlite3_free(pPrior);
    return 0;
  }
  nOld = memsys3Size(pPrior);
  if( nBytes<=nOld && nBytes>=nOld-128 ){
    return pPrior;
  }
  memsys3Enter();
  p = memsys3MallocUnsafe(nBytes);
  if( p ){
    if( nOld<nBytes ){
      memcpy(p, pPrior, nOld);
    }else{
      memcpy(p, pPrior, nBytes);
    }
    memsys3FreeUnsafe(pPrior);
  }
  memsys3Leave();
  return p;
}

/*
** Initialize this module.
*/
static int memsys3Init(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  if( !sqlite3GlobalConfig.pHeap ){
    return SQLITE_ERROR;
  }

  /* Store a pointer to the memory block in global structure mem3. */
  assert( sizeof(Mem3Block)==8 );
  mem3.aPool = (Mem3Block *)sqlite3GlobalConfig.pHeap;
  mem3.nPool = (sqlite3GlobalConfig.nHeap / sizeof(Mem3Block)) - 2;

  /* Initialize the master block. */
  mem3.szMaster = mem3.nPool;
  mem3.mnMaster = mem3.szMaster;
  mem3.iMaster = 1;
  mem3.aPool[0].u.hdr.size4x = (mem3.szMaster<<2) + 2;
  mem3.aPool[mem3.nPool].u.hdr.prevSize = mem3.nPool;
  mem3.aPool[mem3.nPool].u.hdr.size4x = 1;

  return SQLITE_OK;
}

/*
** Deinitialize this module.
*/
static void memsys3Shutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  mem3.mutex = 0;
  return;
}



/*
** Open the file indicated and write a log of all unfreed memory
** allocations into that log.
*/
SQLITE_PRIVATE void sqlite3Memsys3Dump(const char *zFilename){
#ifdef SQLITE_DEBUG
  FILE *out;
  u32 i, j;
  u32 size;
  if( zFilename==0 || zFilename[0]==0 ){
    out = stdout;
  }else{
    out = fopen(zFilename, "w");
    if( out==0 ){
      fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
                      zFilename);
      return;
    }
  }
  memsys3Enter();
  fprintf(out, "CHUNKS:\n");
  for(i=1; i<=mem3.nPool; i+=size/4){
    size = mem3.aPool[i-1].u.hdr.size4x;
    if( size/4<=1 ){
      fprintf(out, "%p size error\n", &mem3.aPool[i]);
      assert( 0 );
      break;
    }
    if( (size&1)==0 && mem3.aPool[i+size/4-1].u.hdr.prevSize!=size/4 ){
      fprintf(out, "%p tail size does not match\n", &mem3.aPool[i]);
      assert( 0 );
      break;
    }
    if( ((mem3.aPool[i+size/4-1].u.hdr.size4x&2)>>1)!=(size&1) ){
      fprintf(out, "%p tail checkout bit is incorrect\n", &mem3.aPool[i]);
      assert( 0 );
      break;
    }
    if( size&1 ){
      fprintf(out, "%p %6d bytes checked out\n", &mem3.aPool[i], (size/4)*8-8);
    }else{
      fprintf(out, "%p %6d bytes free%s\n", &mem3.aPool[i], (size/4)*8-8,
                  i==mem3.iMaster ? " **master**" : "");
    }
  }
  for(i=0; i<MX_SMALL-1; i++){
    if( mem3.aiSmall[i]==0 ) continue;
    fprintf(out, "small(%2d):", i);
    for(j = mem3.aiSmall[i]; j>0; j=mem3.aPool[j].u.list.next){
      fprintf(out, " %p(%d)", &mem3.aPool[j],
              (mem3.aPool[j-1].u.hdr.size4x/4)*8-8);
    }
    fprintf(out, "\n");
  }
  for(i=0; i<N_HASH; i++){
    if( mem3.aiHash[i]==0 ) continue;
    fprintf(out, "hash(%2d):", i);
    for(j = mem3.aiHash[i]; j>0; j=mem3.aPool[j].u.list.next){
      fprintf(out, " %p(%d)", &mem3.aPool[j],
              (mem3.aPool[j-1].u.hdr.size4x/4)*8-8);
    }
    fprintf(out, "\n");
  }
  fprintf(out, "master=%d\n", mem3.iMaster);
  fprintf(out, "nowUsed=%d\n", mem3.nPool*8 - mem3.szMaster*8);
  fprintf(out, "mxUsed=%d\n", mem3.nPool*8 - mem3.mnMaster*8);
  sqlite3_mutex_leave(mem3.mutex);
  if( out==stdout ){
    fflush(stdout);
  }else{
    fclose(out);
  }
#else
  UNUSED_PARAMETER(zFilename);
#endif
}

/*
** This routine is the only routine in this file with external
** linkage.
**
** Populate the low-level memory allocation function pointers in
** sqlite3GlobalConfig.m with pointers to the routines in this file. The
** arguments specify the block of memory to manage.
**
** This routine is only called by sqlite3_config(), and therefore
** is not required to be threadsafe (it is not).
*/
SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys3(void){
  static const sqlite3_mem_methods mempoolMethods = {
     memsys3Malloc,
     memsys3Free,
     memsys3Realloc,
     memsys3Size,
     memsys3Roundup,
     memsys3Init,
     memsys3Shutdown,
     0
  };
  return &mempoolMethods;
}

#endif /* SQLITE_ENABLE_MEMSYS3 */

/************** End of mem3.c ************************************************/
/************** Begin file mem5.c ********************************************/
/*
** 2007 October 14
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.
**
** This version of the memory allocation subsystem omits all
** use of malloc(). The application gives SQLite a block of memory
** before calling sqlite3_initialize() from which allocations
** are made and returned by the xMalloc() and xRealloc()
** implementations. Once sqlite3_initialize() has been called,
** the amount of memory available to SQLite is fixed and cannot
** be changed.
**
** This version of the memory allocation subsystem is included
** in the build only if SQLITE_ENABLE_MEMSYS5 is defined.
**
** This memory allocator uses the following algorithm:
**
**   1.  All memory allocations sizes are rounded up to a power of 2.
**
**   2.  If two adjacent free blocks are the halves of a larger block,
**       then the two blocks are coalesed into the single larger block.
**
**   3.  New memory is allocated from the first available free block.
**
** This algorithm is described in: J. M. Robson. "Bounds for Some Functions
** Concerning Dynamic Storage Allocation". Journal of the Association for
** Computing Machinery, Volume 21, Number 8, July 1974, pages 491-499.
**
** Let n be the size of the largest allocation divided by the minimum
** allocation size (after rounding all sizes up to a power of 2.)  Let M
** be the maximum amount of memory ever outstanding at one time.  Let
** N be the total amount of memory available for allocation.  Robson
** proved that this memory allocator will never breakdown due to
** fragmentation as long as the following constraint holds:
**
**      N >=  M*(1 + log2(n)/2) - n + 1
**
** The sqlite3_status() logic tracks the maximum values of n and M so
** that an application can, at any time, verify this constraint.
*/

/*
** This version of the memory allocator is used only when
** SQLITE_ENABLE_MEMSYS5 is defined.
*/
#ifdef SQLITE_ENABLE_MEMSYS5

/*
** A minimum allocation is an instance of the following structure.
** Larger allocations are an array of these structures where the
** size of the array is a power of 2.
**
** The size of this object must be a power of two.  That fact is
** verified in memsys5Init().
*/
typedef struct Mem5Link Mem5Link;
struct Mem5Link {
  int next;       /* Index of next free chunk */
  int prev;       /* Index of previous free chunk */
};

/*
** Maximum size of any allocation is ((1<<LOGMAX)*mem5.szAtom). Since
** mem5.szAtom is always at least 8 and 32-bit integers are used,
** it is not actually possible to reach this limit.
*/
#define LOGMAX 30

/*
** Masks used for mem5.aCtrl[] elements.
*/
#define CTRL_LOGSIZE  0x1f    /* Log2 Size of this block */
#define CTRL_FREE     0x20    /* True if not checked out */

/*
** All of the static variables used by this module are collected
** into a single structure named "mem5".  This is to keep the
** static variables organized and to reduce namespace pollution
** when this module is combined with other in the amalgamation.
*/
static SQLITE_WSD struct Mem5Global {
  /*
  ** Memory available for allocation
  */
  int szAtom;      /* Smallest possible allocation in bytes */
  int nBlock;      /* Number of szAtom sized blocks in zPool */
  u8 *zPool;       /* Memory available to be allocated */

  /*
  ** Mutex to control access to the memory allocation subsystem.
  */
  sqlite3_mutex *mutex;

  /*
  ** Performance statistics
  */
  u64 nAlloc;         /* Total number of calls to malloc */
  u64 totalAlloc;     /* Total of all malloc calls - includes internal frag */
  u64 totalExcess;    /* Total internal fragmentation */
  u32 currentOut;     /* Current checkout, including internal fragmentation */
  u32 currentCount;   /* Current number of distinct checkouts */
  u32 maxOut;         /* Maximum instantaneous currentOut */
  u32 maxCount;       /* Maximum instantaneous currentCount */
  u32 maxRequest;     /* Largest allocation (exclusive of internal frag) */

  /*
  ** Lists of free blocks.  aiFreelist[0] is a list of free blocks of
  ** size mem5.szAtom.  aiFreelist[1] holds blocks of size szAtom*2.
  ** and so forth.
  */
  int aiFreelist[LOGMAX+1];

  /*
  ** Space for tracking which blocks are checked out and the size
  ** of each block.  One byte per block.
  */
  u8 *aCtrl;

} mem5 = { 0 };

/*
** Access the static variable through a macro for SQLITE_OMIT_WSD
*/
#define mem5 GLOBAL(struct Mem5Global, mem5)

/*
** Assuming mem5.zPool is divided up into an array of Mem5Link
** structures, return a pointer to the idx-th such lik.
*/
#define MEM5LINK(idx) ((Mem5Link *)(&mem5.zPool[(idx)*mem5.szAtom]))

/*
** Unlink the chunk at mem5.aPool[i] from list it is currently
** on.  It should be found on mem5.aiFreelist[iLogsize].
*/
static void memsys5Unlink(int i, int iLogsize){
  int next, prev;
  assert( i>=0 && i<mem5.nBlock );
  assert( iLogsize>=0 && iLogsize<=LOGMAX );
  assert( (mem5.aCtrl[i] & CTRL_LOGSIZE)==iLogsize );

  next = MEM5LINK(i)->next;
  prev = MEM5LINK(i)->prev;
  if( prev<0 ){
    mem5.aiFreelist[iLogsize] = next;
  }else{
    MEM5LINK(prev)->next = next;
  }
  if( next>=0 ){
    MEM5LINK(next)->prev = prev;
  }
}

/*
** Link the chunk at mem5.aPool[i] so that is on the iLogsize
** free list.
*/
static void memsys5Link(int i, int iLogsize){
  int x;
  assert( sqlite3_mutex_held(mem5.mutex) );
  assert( i>=0 && i<mem5.nBlock );
  assert( iLogsize>=0 && iLogsize<=LOGMAX );
  assert( (mem5.aCtrl[i] & CTRL_LOGSIZE)==iLogsize );

  x = MEM5LINK(i)->next = mem5.aiFreelist[iLogsize];
  MEM5LINK(i)->prev = -1;
  if( x>=0 ){
    assert( x<mem5.nBlock );
    MEM5LINK(x)->prev = i;
  }
  mem5.aiFreelist[iLogsize] = i;
}

/*
** If the STATIC_MEM mutex is not already held, obtain it now. The mutex
** will already be held (obtained by code in malloc.c) if
** sqlite3GlobalConfig.bMemStat is true.
*/
static void memsys5Enter(void){
  sqlite3_mutex_enter(mem5.mutex);
}
static void memsys5Leave(void){
  sqlite3_mutex_leave(mem5.mutex);
}

/*
** Return the size of an outstanding allocation, in bytes.  The
** size returned omits the 8-byte header overhead.  This only
** works for chunks that are currently checked out.
*/
static int memsys5Size(void *p){
  int iSize = 0;
  if( p ){
    int i = ((u8 *)p-mem5.zPool)/mem5.szAtom;
    assert( i>=0 && i<mem5.nBlock );
    iSize = mem5.szAtom * (1 << (mem5.aCtrl[i]&CTRL_LOGSIZE));
  }
  return iSize;
}

/*
** Find the first entry on the freelist iLogsize.  Unlink that
** entry and return its index.
*/
static int memsys5UnlinkFirst(int iLogsize){
  int i;
  int iFirst;

  assert( iLogsize>=0 && iLogsize<=LOGMAX );
  i = iFirst = mem5.aiFreelist[iLogsize];
  assert( iFirst>=0 );
  while( i>0 ){
    if( i<iFirst ) iFirst = i;
    i = MEM5LINK(i)->next;
  }
  memsys5Unlink(iFirst, iLogsize);
  return iFirst;
}

/*
** Return a block of memory of at least nBytes in size.
** Return NULL if unable.  Return NULL if nBytes==0.
**
** The caller guarantees that nByte positive.
**
** The caller has obtained a mutex prior to invoking this
** routine so there is never any chance that two or more
** threads can be in this routine at the same time.
*/
static void *memsys5MallocUnsafe(int nByte){
  int i;           /* Index of a mem5.aPool[] slot */
  int iBin;        /* Index into mem5.aiFreelist[] */
  int iFullSz;     /* Size of allocation rounded up to power of 2 */
  int iLogsize;    /* Log2 of iFullSz/POW2_MIN */

  /* nByte must be a positive */
  assert( nByte>0 );

  /* Keep track of the maximum allocation request.  Even unfulfilled
  ** requests are counted */
  if( (u32)nByte>mem5.maxRequest ){
    mem5.maxRequest = nByte;
  }

  /* Abort if the requested allocation size is larger than the largest
  ** power of two that we can represent using 32-bit signed integers.
  */
  if( nByte > 0x40000000 ){
    return 0;
  }

  /* Round nByte up to the next valid power of two */
  for(iFullSz=mem5.szAtom, iLogsize=0; iFullSz<nByte; iFullSz *= 2, iLogsize++){}

  /* Make sure mem5.aiFreelist[iLogsize] contains at least one free
  ** block.  If not, then split a block of the next larger power of
  ** two in order to create a new free block of size iLogsize.
  */
  for(iBin=iLogsize; mem5.aiFreelist[iBin]<0 && iBin<=LOGMAX; iBin++){}
  if( iBin>LOGMAX ){
    testcase( sqlite3GlobalConfig.xLog!=0 );
    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes", nByte);
    return 0;
  }
  i = memsys5UnlinkFirst(iBin);
  while( iBin>iLogsize ){
    int newSize;

    iBin--;
    newSize = 1 << iBin;
    mem5.aCtrl[i+newSize] = CTRL_FREE | iBin;
    memsys5Link(i+newSize, iBin);
  }
  mem5.aCtrl[i] = iLogsize;

  /* Update allocator performance statistics. */
  mem5.nAlloc++;
  mem5.totalAlloc += iFullSz;
  mem5.totalExcess += iFullSz - nByte;
  mem5.currentCount++;
  mem5.currentOut += iFullSz;
  if( mem5.maxCount<mem5.currentCount ) mem5.maxCount = mem5.currentCount;
  if( mem5.maxOut<mem5.currentOut ) mem5.maxOut = mem5.currentOut;

  /* Return a pointer to the allocated memory. */
  return (void*)&mem5.zPool[i*mem5.szAtom];
}

/*
** Free an outstanding memory allocation.
*/
static void memsys5FreeUnsafe(void *pOld){
  u32 size, iLogsize;
  int iBlock;

  /* Set iBlock to the index of the block pointed to by pOld in
  ** the array of mem5.szAtom byte blocks pointed to by mem5.zPool.
  */
  iBlock = ((u8 *)pOld-mem5.zPool)/mem5.szAtom;

  /* Check that the pointer pOld points to a valid, non-free block. */
  assert( iBlock>=0 && iBlock<mem5.nBlock );
  assert( ((u8 *)pOld-mem5.zPool)%mem5.szAtom==0 );
  assert( (mem5.aCtrl[iBlock] & CTRL_FREE)==0 );

  iLogsize = mem5.aCtrl[iBlock] & CTRL_LOGSIZE;
  size = 1<<iLogsize;
  assert( iBlock+size-1<(u32)mem5.nBlock );

  mem5.aCtrl[iBlock] |= CTRL_FREE;
  mem5.aCtrl[iBlock+size-1] |= CTRL_FREE;
  assert( mem5.currentCount>0 );
  assert( mem5.currentOut>=(size*mem5.szAtom) );
  mem5.currentCount--;
  mem5.currentOut -= size*mem5.szAtom;
  assert( mem5.currentOut>0 || mem5.currentCount==0 );
  assert( mem5.currentCount>0 || mem5.currentOut==0 );

  mem5.aCtrl[iBlock] = CTRL_FREE | iLogsize;
  while( ALWAYS(iLogsize<LOGMAX) ){
    int iBuddy;
    if( (iBlock>>iLogsize) & 1 ){
      iBuddy = iBlock - size;
    }else{
      iBuddy = iBlock + size;
    }
    assert( iBuddy>=0 );
    if( (iBuddy+(1<<iLogsize))>mem5.nBlock ) break;
    if( mem5.aCtrl[iBuddy]!=(CTRL_FREE | iLogsize) ) break;
    memsys5Unlink(iBuddy, iLogsize);
    iLogsize++;
    if( iBuddy<iBlock ){
      mem5.aCtrl[iBuddy] = CTRL_FREE | iLogsize;
      mem5.aCtrl[iBlock] = 0;
      iBlock = iBuddy;
    }else{
      mem5.aCtrl[iBlock] = CTRL_FREE | iLogsize;
      mem5.aCtrl[iBuddy] = 0;
    }
    size *= 2;
  }
  memsys5Link(iBlock, iLogsize);
}

/*
** Allocate nBytes of memory
*/
static void *memsys5Malloc(int nBytes){
  sqlite3_int64 *p = 0;
  if( nBytes>0 ){
    memsys5Enter();
    p = memsys5MallocUnsafe(nBytes);
    memsys5Leave();
  }
  return (void*)p;
}

/*
** Free memory.
**
** The outer layer memory allocator prevents this routine from
** being called with pPrior==0.
*/
static void memsys5Free(void *pPrior){
  assert( pPrior!=0 );
  memsys5Enter();
  memsys5FreeUnsafe(pPrior);
  memsys5Leave();
}

/*
** Change the size of an existing memory allocation.
**
** The outer layer memory allocator prevents this routine from
** being called with pPrior==0.
**
** nBytes is always a value obtained from a prior call to
** memsys5Round().  Hence nBytes is always a non-negative power
** of two.  If nBytes==0 that means that an oversize allocation
** (an allocation larger than 0x40000000) was requested and this
** routine should return 0 without freeing pPrior.
*/
static void *memsys5Realloc(void *pPrior, int nBytes){
  int nOld;
  void *p;
  assert( pPrior!=0 );
  assert( (nBytes&(nBytes-1))==0 );
  assert( nBytes>=0 );
  if( nBytes==0 ){
    return 0;
  }
  nOld = memsys5Size(pPrior);
  if( nBytes<=nOld ){
    return pPrior;
  }
  memsys5Enter();
  p = memsys5MallocUnsafe(nBytes);
  if( p ){
    memcpy(p, pPrior, nOld);
    memsys5FreeUnsafe(pPrior);
  }
  memsys5Leave();
  return p;
}

/*
** Round up a request size to the next valid allocation size.  If
** the allocation is too large to be handled by this allocation system,
** return 0.
**
** All allocations must be a power of two and must be expressed by a
** 32-bit signed integer.  Hence the largest allocation is 0x40000000
** or 1073741824 bytes.
*/
static int memsys5Roundup(int n){
  int iFullSz;
  if( n > 0x40000000 ) return 0;
  for(iFullSz=mem5.szAtom; iFullSz<n; iFullSz *= 2);
  return iFullSz;
}

/*
** Return the ceiling of the logarithm base 2 of iValue.
**
** Examples:   memsys5Log(1) -> 0
**             memsys5Log(2) -> 1
**             memsys5Log(4) -> 2
**             memsys5Log(5) -> 3
**             memsys5Log(8) -> 3
**             memsys5Log(9) -> 4
*/
static int memsys5Log(int iValue){
  int iLog;
  for(iLog=0; (1<<iLog)<iValue; iLog++);
  return iLog;
}

/*
** Initialize the memory allocator.
**
** This routine is not threadsafe.  The caller must be holding a mutex
** to prevent multiple threads from entering at the same time.
*/
static int memsys5Init(void *NotUsed){
  int ii;            /* Loop counter */
  int nByte;         /* Number of bytes of memory available to this allocator */
  u8 *zByte;         /* Memory usable by this allocator */
  int nMinLog;       /* Log base 2 of minimum allocation size in bytes */
  int iOffset;       /* An offset into mem5.aCtrl[] */

  UNUSED_PARAMETER(NotUsed);

  /* For the purposes of this routine, disable the mutex */
  mem5.mutex = 0;

  /* The size of a Mem5Link object must be a power of two.  Verify that
  ** this is case.
  */
  assert( (sizeof(Mem5Link)&(sizeof(Mem5Link)-1))==0 );

  nByte = sqlite3GlobalConfig.nHeap;
  zByte = (u8*)sqlite3GlobalConfig.pHeap;
  assert( zByte!=0 );  /* sqlite3_config() does not allow otherwise */

  nMinLog = memsys5Log(sqlite3GlobalConfig.mnReq);
  mem5.szAtom = (1<<nMinLog);
  while( (int)sizeof(Mem5Link)>mem5.szAtom ){
    mem5.szAtom = mem5.szAtom << 1;
  }

  mem5.nBlock = (nByte / (mem5.szAtom+sizeof(u8)));
  mem5.zPool = zByte;
  mem5.aCtrl = (u8 *)&mem5.zPool[mem5.nBlock*mem5.szAtom];

  for(ii=0; ii<=LOGMAX; ii++){
    mem5.aiFreelist[ii] = -1;
  }

  iOffset = 0;
  for(ii=LOGMAX; ii>=0; ii--){
    int nAlloc = (1<<ii);
    if( (iOffset+nAlloc)<=mem5.nBlock ){
      mem5.aCtrl[iOffset] = ii | CTRL_FREE;
      memsys5Link(iOffset, ii);
      iOffset += nAlloc;
    }
    assert((iOffset+nAlloc)>mem5.nBlock);
  }

  /* If a mutex is required for normal operation, allocate one */
  if( sqlite3GlobalConfig.bMemstat==0 ){
    mem5.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
  }

  return SQLITE_OK;
}

/*
** Deinitialize this module.
*/
static void memsys5Shutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  mem5.mutex = 0;
  return;
}

#ifdef SQLITE_TEST
/*
** Open the file indicated and write a log of all unfreed memory
** allocations into that log.
*/
SQLITE_PRIVATE void sqlite3Memsys5Dump(const char *zFilename){
  FILE *out;
  int i, j, n;
  int nMinLog;

  if( zFilename==0 || zFilename[0]==0 ){
    out = stdout;
  }else{
    out = fopen(zFilename, "w");
    if( out==0 ){
      fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
                      zFilename);
      return;
    }
  }
  memsys5Enter();
  nMinLog = memsys5Log(mem5.szAtom);
  for(i=0; i<=LOGMAX && i+nMinLog<32; i++){
    for(n=0, j=mem5.aiFreelist[i]; j>=0; j = MEM5LINK(j)->next, n++){}
    fprintf(out, "freelist items of size %d: %d\n", mem5.szAtom << i, n);
  }
  fprintf(out, "mem5.nAlloc       = %llu\n", mem5.nAlloc);
  fprintf(out, "mem5.totalAlloc   = %llu\n", mem5.totalAlloc);
  fprintf(out, "mem5.totalExcess  = %llu\n", mem5.totalExcess);
  fprintf(out, "mem5.currentOut   = %u\n", mem5.currentOut);
  fprintf(out, "mem5.currentCount = %u\n", mem5.currentCount);
  fprintf(out, "mem5.maxOut       = %u\n", mem5.maxOut);
  fprintf(out, "mem5.maxCount     = %u\n", mem5.maxCount);
  fprintf(out, "mem5.maxRequest   = %u\n", mem5.maxRequest);
  memsys5Leave();
  if( out==stdout ){
    fflush(stdout);
  }else{
    fclose(out);
  }
}
#endif

/*
** This routine is the only routine in this file with external
** linkage. It returns a pointer to a static sqlite3_mem_methods
** struct populated with the memsys5 methods.
*/
SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys5(void){
  static const sqlite3_mem_methods memsys5Methods = {
     memsys5Malloc,
     memsys5Free,
     memsys5Realloc,
     memsys5Size,
     memsys5Roundup,
     memsys5Init,
     memsys5Shutdown,
     0
  };
  return &memsys5Methods;
}

#endif /* SQLITE_ENABLE_MEMSYS5 */

/************** End of mem5.c ************************************************/
/************** Begin file mutex.c *******************************************/
/*
** 2007 August 14
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes.
**
** This file contains code that is common across all mutex implementations.
*/

#if defined(SQLITE_DEBUG) && !defined(SQLITE_MUTEX_OMIT)
/*
** For debugging purposes, record when the mutex subsystem is initialized
** and uninitialized so that we can assert() if there is an attempt to
** allocate a mutex while the system is uninitialized.
*/
static SQLITE_WSD int mutexIsInit = 0;
#endif /* SQLITE_DEBUG */


#ifndef SQLITE_MUTEX_OMIT
/*
** Initialize the mutex system.
*/
SQLITE_PRIVATE int sqlite3MutexInit(void){
  int rc = SQLITE_OK;
  if( sqlite3GlobalConfig.bCoreMutex ){
    if( !sqlite3GlobalConfig.mutex.xMutexAlloc ){
      /* If the xMutexAlloc method has not been set, then the user did not
      ** install a mutex implementation via sqlite3_config() prior to
      ** sqlite3_initialize() being called. This block copies pointers to
      ** the default implementation into the sqlite3GlobalConfig structure.
      */
      sqlite3_mutex_methods *pFrom = sqlite3DefaultMutex();
      sqlite3_mutex_methods *pTo = &sqlite3GlobalConfig.mutex;

      memcpy(pTo, pFrom, offsetof(sqlite3_mutex_methods, xMutexAlloc));
      memcpy(&pTo->xMutexFree, &pFrom->xMutexFree,
             sizeof(*pTo) - offsetof(sqlite3_mutex_methods, xMutexFree));
      pTo->xMutexAlloc = pFrom->xMutexAlloc;
    }
    rc = sqlite3GlobalConfig.mutex.xMutexInit();
  }

#ifdef SQLITE_DEBUG
  GLOBAL(int, mutexIsInit) = 1;
#endif

  return rc;
}

/*
** Shutdown the mutex system. This call frees resources allocated by
** sqlite3MutexInit().
*/
SQLITE_PRIVATE int sqlite3MutexEnd(void){
  int rc = SQLITE_OK;
  if( sqlite3GlobalConfig.mutex.xMutexEnd ){
    rc = sqlite3GlobalConfig.mutex.xMutexEnd();
  }

#ifdef SQLITE_DEBUG
  GLOBAL(int, mutexIsInit) = 0;
#endif

  return rc;
}

/*
** Retrieve a pointer to a static mutex or allocate a new dynamic one.
*/
SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int id){
#ifndef SQLITE_OMIT_AUTOINIT
  if( sqlite3_initialize() ) return 0;
#endif
  return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
}

SQLITE_PRIVATE sqlite3_mutex *sqlite3MutexAlloc(int id){
  if( !sqlite3GlobalConfig.bCoreMutex ){
    return 0;
  }
  assert( GLOBAL(int, mutexIsInit) );
  return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
}

/*
** Free a dynamic mutex.
*/
SQLITE_API void sqlite3_mutex_free(sqlite3_mutex *p){
  if( p ){
    sqlite3GlobalConfig.mutex.xMutexFree(p);
  }
}

/*
** Obtain the mutex p. If some other thread already has the mutex, block
** until it can be obtained.
*/
SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex *p){
  if( p ){
    sqlite3GlobalConfig.mutex.xMutexEnter(p);
  }
}

/*
** Obtain the mutex p. If successful, return SQLITE_OK. Otherwise, if another
** thread holds the mutex and it cannot be obtained, return SQLITE_BUSY.
*/
SQLITE_API int sqlite3_mutex_try(sqlite3_mutex *p){
  int rc = SQLITE_OK;
  if( p ){
    return sqlite3GlobalConfig.mutex.xMutexTry(p);
  }
  return rc;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was previously
** entered by the same thread.  The behavior is undefined if the mutex
** is not currently entered. If a NULL pointer is passed as an argument
** this function is a no-op.
*/
SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex *p){
  if( p ){
    sqlite3GlobalConfig.mutex.xMutexLeave(p);
  }
}

#ifndef NDEBUG
/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use inside assert() statements.
*/
SQLITE_API int sqlite3_mutex_held(sqlite3_mutex *p){
  return p==0 || sqlite3GlobalConfig.mutex.xMutexHeld(p);
}
SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex *p){
  return p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld(p);
}
#endif

#endif /* SQLITE_MUTEX_OMIT */

/************** End of mutex.c ***********************************************/
/************** Begin file mutex_noop.c **************************************/
/*
** 2008 October 07
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes.
**
** This implementation in this file does not provide any mutual
** exclusion and is thus suitable for use only in applications
** that use SQLite in a single thread.  The routines defined
** here are place-holders.  Applications can substitute working
** mutex routines at start-time using the
**
**     sqlite3_config(SQLITE_CONFIG_MUTEX,...)
**
** interface.
**
** If compiled with SQLITE_DEBUG, then additional logic is inserted
** that does error checking on mutexes to make sure they are being
** called correctly.
*/


#if defined(SQLITE_MUTEX_NOOP) && !defined(SQLITE_DEBUG)
/*
** Stub routines for all mutex methods.
**
** This routines provide no mutual exclusion or error checking.
*/
static int noopMutexHeld(sqlite3_mutex *p){ return 1; }
static int noopMutexNotheld(sqlite3_mutex *p){ return 1; }
static int noopMutexInit(void){ return SQLITE_OK; }
static int noopMutexEnd(void){ return SQLITE_OK; }
static sqlite3_mutex *noopMutexAlloc(int id){ return (sqlite3_mutex*)8; }
static void noopMutexFree(sqlite3_mutex *p){ return; }
static void noopMutexEnter(sqlite3_mutex *p){ return; }
static int noopMutexTry(sqlite3_mutex *p){ return SQLITE_OK; }
static void noopMutexLeave(sqlite3_mutex *p){ return; }

SQLITE_PRIVATE sqlite3_mutex_methods *sqlite3DefaultMutex(void){
  static sqlite3_mutex_methods sMutex = {
    noopMutexInit,
    noopMutexEnd,
    noopMutexAlloc,
    noopMutexFree,
    noopMutexEnter,
    noopMutexTry,
    noopMutexLeave,

    noopMutexHeld,
    noopMutexNotheld
  };

  return &sMutex;
}
#endif /* defined(SQLITE_MUTEX_NOOP) && !defined(SQLITE_DEBUG) */

#if defined(SQLITE_MUTEX_NOOP) && defined(SQLITE_DEBUG)
/*
** In this implementation, error checking is provided for testing
** and debugging purposes.  The mutexes still do not provide any
** mutual exclusion.
*/

/*
** The mutex object
*/
struct sqlite3_mutex {
  int id;     /* The mutex type */
  int cnt;    /* Number of entries without a matching leave */
};

/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use inside assert() statements.
*/
static int debugMutexHeld(sqlite3_mutex *p){
  return p==0 || p->cnt>0;
}
static int debugMutexNotheld(sqlite3_mutex *p){
  return p==0 || p->cnt==0;
}

/*
** Initialize and deinitialize the mutex subsystem.
*/
static int debugMutexInit(void){ return SQLITE_OK; }
static int debugMutexEnd(void){ return SQLITE_OK; }

/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated.
*/
static sqlite3_mutex *debugMutexAlloc(int id){
  static sqlite3_mutex aStatic[6];
  sqlite3_mutex *pNew = 0;
  switch( id ){
    case SQLITE_MUTEX_FAST:
    case SQLITE_MUTEX_RECURSIVE: {
      pNew = sqlite3Malloc(sizeof(*pNew));
      if( pNew ){
        pNew->id = id;
        pNew->cnt = 0;
      }
      break;
    }
    default: {
      assert( id-2 >= 0 );
      assert( id-2 < (int)(sizeof(aStatic)/sizeof(aStatic[0])) );
      pNew = &aStatic[id-2];
      pNew->id = id;
      break;
    }
  }
  return pNew;
}

/*
** This routine deallocates a previously allocated mutex.
*/
static void debugMutexFree(sqlite3_mutex *p){
  assert( p->cnt==0 );
  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
  sqlite3_free(p);
}

/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void debugMutexEnter(sqlite3_mutex *p){
  assert( p->id==SQLITE_MUTEX_RECURSIVE || debugMutexNotheld(p) );
  p->cnt++;
}
static int debugMutexTry(sqlite3_mutex *p){
  assert( p->id==SQLITE_MUTEX_RECURSIVE || debugMutexNotheld(p) );
  p->cnt++;
  return SQLITE_OK;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
*/
static void debugMutexLeave(sqlite3_mutex *p){
  assert( debugMutexHeld(p) );
  p->cnt--;
  assert( p->id==SQLITE_MUTEX_RECURSIVE || debugMutexNotheld(p) );
}

SQLITE_PRIVATE sqlite3_mutex_methods *sqlite3DefaultMutex(void){
  static sqlite3_mutex_methods sMutex = {
    debugMutexInit,
    debugMutexEnd,
    debugMutexAlloc,
    debugMutexFree,
    debugMutexEnter,
    debugMutexTry,
    debugMutexLeave,

    debugMutexHeld,
    debugMutexNotheld
  };

  return &sMutex;
}
#endif /* defined(SQLITE_MUTEX_NOOP) && defined(SQLITE_DEBUG) */

/************** End of mutex_noop.c ******************************************/
/************** Begin file mutex_os2.c ***************************************/
/*
** 2007 August 28
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for OS/2
*/

/*
** The code in this file is only used if SQLITE_MUTEX_OS2 is defined.
** See the mutex.h file for details.
*/
#ifdef SQLITE_MUTEX_OS2

/********************** OS/2 Mutex Implementation **********************
**
** This implementation of mutexes is built using the OS/2 API.
*/

/*
** The mutex object
** Each recursive mutex is an instance of the following structure.
*/
struct sqlite3_mutex {
  HMTX mutex;       /* Mutex controlling the lock */
  int  id;          /* Mutex type */
  int  nRef;        /* Number of references */
  TID  owner;       /* Thread holding this mutex */
};

#define OS2_MUTEX_INITIALIZER   0,0,0,0

/*
** Initialize and deinitialize the mutex subsystem.
*/
static int os2MutexInit(void){ return SQLITE_OK; }
static int os2MutexEnd(void){ return SQLITE_OK; }

/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated.
** SQLite will unwind its stack and return an error.  The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li>  SQLITE_MUTEX_FAST               0
** <li>  SQLITE_MUTEX_RECURSIVE          1
** <li>  SQLITE_MUTEX_STATIC_MASTER      2
** <li>  SQLITE_MUTEX_STATIC_MEM         3
** <li>  SQLITE_MUTEX_STATIC_PRNG        4
** </ul>
**
** The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
** not want to.  But SQLite will only request a recursive mutex in
** cases where it really needs one.  If a faster non-recursive mutex
** implementation is available on the host platform, the mutex subsystem
** might return such a mutex in response to SQLITE_MUTEX_FAST.
**
** The other allowed parameters to sqlite3_mutex_alloc() each return
** a pointer to a static preexisting mutex.  Three static mutexes are
** used by the current version of SQLite.  Future versions of SQLite
** may add additional static mutexes.  Static mutexes are for internal
** use by SQLite only.  Applications that use SQLite mutexes should
** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
** SQLITE_MUTEX_RECURSIVE.
**
** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
** returns a different mutex on every call.  But for the static
** mutex types, the same mutex is returned on every call that has
** the same type number.
*/
static sqlite3_mutex *os2MutexAlloc(int iType){
  sqlite3_mutex *p = NULL;
  switch( iType ){
    case SQLITE_MUTEX_FAST:
    case SQLITE_MUTEX_RECURSIVE: {
      p = sqlite3MallocZero( sizeof(*p) );
      if( p ){
        p->id = iType;
        if( DosCreateMutexSem( 0, &p->mutex, 0, FALSE ) != NO_ERROR ){
          sqlite3_free( p );
          p = NULL;
        }
      }
      break;
    }
    default: {
      static volatile int isInit = 0;
      static sqlite3_mutex staticMutexes[] = {
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
      };
      if ( !isInit ){
        APIRET rc;
        PTIB ptib;
        PPIB ppib;
        HMTX mutex;
        char name[32];
        DosGetInfoBlocks( &ptib, &ppib );
        sqlite3_snprintf( sizeof(name), name, "\\SEM32\\SQLITE%04x",
                          ppib->pib_ulpid );
        while( !isInit ){
          mutex = 0;
          rc = DosCreateMutexSem( name, &mutex, 0, FALSE);
          if( rc == NO_ERROR ){
            unsigned int i;
            if( !isInit ){
              for( i = 0; i < sizeof(staticMutexes)/sizeof(staticMutexes[0]); i++ ){
                DosCreateMutexSem( 0, &staticMutexes[i].mutex, 0, FALSE );
              }
              isInit = 1;
            }
            DosCloseMutexSem( mutex );
          }else if( rc == ERROR_DUPLICATE_NAME ){
            DosSleep( 1 );
          }else{
            return p;
          }
        }
      }
      assert( iType-2 >= 0 );
      assert( iType-2 < sizeof(staticMutexes)/sizeof(staticMutexes[0]) );
      p = &staticMutexes[iType-2];
      p->id = iType;
      break;
    }
  }
  return p;
}


/*
** This routine deallocates a previously allocated mutex.
** SQLite is careful to deallocate every mutex that it allocates.
*/
static void os2MutexFree(sqlite3_mutex *p){
  if( p==0 ) return;
  assert( p->nRef==0 );
  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
  DosCloseMutexSem( p->mutex );
  sqlite3_free( p );
}

#ifdef SQLITE_DEBUG
/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use inside assert() statements.
*/
static int os2MutexHeld(sqlite3_mutex *p){
  TID tid;
  PID pid;
  ULONG ulCount;
  PTIB ptib;
  if( p!=0 ) {
    DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
  } else {
    DosGetInfoBlocks(&ptib, NULL);
    tid = ptib->tib_ptib2->tib2_ultid;
  }
  return p==0 || (p->nRef!=0 && p->owner==tid);
}
static int os2MutexNotheld(sqlite3_mutex *p){
  TID tid;
  PID pid;
  ULONG ulCount;
  PTIB ptib;
  if( p!= 0 ) {
    DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
  } else {
    DosGetInfoBlocks(&ptib, NULL);
    tid = ptib->tib_ptib2->tib2_ultid;
  }
  return p==0 || p->nRef==0 || p->owner!=tid;
}
#endif

/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void os2MutexEnter(sqlite3_mutex *p){
  TID tid;
  PID holder1;
  ULONG holder2;
  if( p==0 ) return;
  assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
  DosRequestMutexSem(p->mutex, SEM_INDEFINITE_WAIT);
  DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
  p->owner = tid;
  p->nRef++;
}
static int os2MutexTry(sqlite3_mutex *p){
  int rc;
  TID tid;
  PID holder1;
  ULONG holder2;
  if( p==0 ) return SQLITE_OK;
  assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
  if( DosRequestMutexSem(p->mutex, SEM_IMMEDIATE_RETURN) == NO_ERROR) {
    DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
    p->owner = tid;
    p->nRef++;
    rc = SQLITE_OK;
  } else {
    rc = SQLITE_BUSY;
  }

  return rc;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
*/
static void os2MutexLeave(sqlite3_mutex *p){
  TID tid;
  PID holder1;
  ULONG holder2;
  if( p==0 ) return;
  assert( p->nRef>0 );
  DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
  assert( p->owner==tid );
  p->nRef--;
  assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
  DosReleaseMutexSem(p->mutex);
}

SQLITE_PRIVATE sqlite3_mutex_methods *sqlite3DefaultMutex(void){
  static sqlite3_mutex_methods sMutex = {
    os2MutexInit,
    os2MutexEnd,
    os2MutexAlloc,
    os2MutexFree,
    os2MutexEnter,
    os2MutexTry,
    os2MutexLeave,
#ifdef SQLITE_DEBUG
    os2MutexHeld,
    os2MutexNotheld
#endif
  };

  return &sMutex;
}
#endif /* SQLITE_MUTEX_OS2 */

/************** End of mutex_os2.c *******************************************/
/************** Begin file mutex_unix.c **************************************/
/*
** 2007 August 28
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for pthreads
*/

/*
** The code in this file is only used if we are compiling threadsafe
** under unix with pthreads.
**
** Note that this implementation requires a version of pthreads that
** supports recursive mutexes.
*/
#ifdef SQLITE_MUTEX_PTHREADS

#include <pthread.h>


/*
** Each recursive mutex is an instance of the following structure.
*/
struct sqlite3_mutex {
  pthread_mutex_t mutex;     /* Mutex controlling the lock */
  int id;                    /* Mutex type */
  int nRef;                  /* Number of entrances */
  pthread_t owner;           /* Thread that is within this mutex */
#ifdef SQLITE_DEBUG
  int trace;                 /* True to trace changes */
#endif
};
#ifdef SQLITE_DEBUG
#define SQLITE3_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER, 0, 0, (pthread_t)0, 0 }
#else
#define SQLITE3_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER, 0, 0, (pthread_t)0 }
#endif

/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use only inside assert() statements.  On some platforms,
** there might be race conditions that can cause these routines to
** deliver incorrect results.  In particular, if pthread_equal() is
** not an atomic operation, then these routines might delivery
** incorrect results.  On most platforms, pthread_equal() is a
** comparison of two integers and is therefore atomic.  But we are
** told that HPUX is not such a platform.  If so, then these routines
** will not always work correctly on HPUX.
**
** On those platforms where pthread_equal() is not atomic, SQLite
** should be compiled without -DSQLITE_DEBUG and with -DNDEBUG to
** make sure no assert() statements are evaluated and hence these
** routines are never called.
*/
#if !defined(NDEBUG) || defined(SQLITE_DEBUG)
static int pthreadMutexHeld(sqlite3_mutex *p){
  return (p->nRef!=0 && pthread_equal(p->owner, pthread_self()));
}
static int pthreadMutexNotheld(sqlite3_mutex *p){
  return p->nRef==0 || pthread_equal(p->owner, pthread_self())==0;
}
#endif

/*
** Initialize and deinitialize the mutex subsystem.
*/
static int pthreadMutexInit(void){ return SQLITE_OK; }
static int pthreadMutexEnd(void){ return SQLITE_OK; }

/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated.  SQLite
** will unwind its stack and return an error.  The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li>  SQLITE_MUTEX_FAST
** <li>  SQLITE_MUTEX_RECURSIVE
** <li>  SQLITE_MUTEX_STATIC_MASTER
** <li>  SQLITE_MUTEX_STATIC_MEM
** <li>  SQLITE_MUTEX_STATIC_MEM2
** <li>  SQLITE_MUTEX_STATIC_PRNG
** <li>  SQLITE_MUTEX_STATIC_LRU
** <li>  SQLITE_MUTEX_STATIC_LRU2
** </ul>
**
** The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
** not want to.  But SQLite will only request a recursive mutex in
** cases where it really needs one.  If a faster non-recursive mutex
** implementation is available on the host platform, the mutex subsystem
** might return such a mutex in response to SQLITE_MUTEX_FAST.
**
** The other allowed parameters to sqlite3_mutex_alloc() each return
** a pointer to a static preexisting mutex.  Six static mutexes are
** used by the current version of SQLite.  Future versions of SQLite
** may add additional static mutexes.  Static mutexes are for internal
** use by SQLite only.  Applications that use SQLite mutexes should
** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
** SQLITE_MUTEX_RECURSIVE.
**
** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
** returns a different mutex on every call.  But for the static
** mutex types, the same mutex is returned on every call that has
** the same type number.
*/
static sqlite3_mutex *pthreadMutexAlloc(int iType){
  static sqlite3_mutex staticMutexes[] = {
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER,
    SQLITE3_MUTEX_INITIALIZER
  };
  sqlite3_mutex *p;
  switch( iType ){
    case SQLITE_MUTEX_RECURSIVE: {
      p = sqlite3MallocZero( sizeof(*p) );
      if( p ){
#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
        /* If recursive mutexes are not available, we will have to
        ** build our own.  See below. */
        pthread_mutex_init(&p->mutex, 0);
#else
        /* Use a recursive mutex if it is available */
        pthread_mutexattr_t recursiveAttr;
        pthread_mutexattr_init(&recursiveAttr);
        pthread_mutexattr_settype(&recursiveAttr, PTHREAD_MUTEX_RECURSIVE);
        pthread_mutex_init(&p->mutex, &recursiveAttr);
        pthread_mutexattr_destroy(&recursiveAttr);
#endif
        p->id = iType;
      }
      break;
    }
    case SQLITE_MUTEX_FAST: {
      p = sqlite3MallocZero( sizeof(*p) );
      if( p ){
        p->id = iType;
        pthread_mutex_init(&p->mutex, 0);
      }
      break;
    }
    default: {
      assert( iType-2 >= 0 );
      assert( iType-2 < ArraySize(staticMutexes) );
      p = &staticMutexes[iType-2];
      p->id = iType;
      break;
    }
  }
  return p;
}


/*
** This routine deallocates a previously
** allocated mutex.  SQLite is careful to deallocate every
** mutex that it allocates.
*/
static void pthreadMutexFree(sqlite3_mutex *p){
  assert( p->nRef==0 );
  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
  pthread_mutex_destroy(&p->mutex);
  sqlite3_free(p);
}

/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void pthreadMutexEnter(sqlite3_mutex *p){
  assert( p->id==SQLITE_MUTEX_RECURSIVE || pthreadMutexNotheld(p) );

#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
  /* If recursive mutexes are not available, then we have to grow
  ** our own.  This implementation assumes that pthread_equal()
  ** is atomic - that it cannot be deceived into thinking self
  ** and p->owner are equal if p->owner changes between two values
  ** that are not equal to self while the comparison is taking place.
  ** This implementation also assumes a coherent cache - that
  ** separate processes cannot read different values from the same
  ** address at the same time.  If either of these two conditions
  ** are not met, then the mutexes will fail and problems will result.
  */
  {
    pthread_t self = pthread_self();
    if( p->nRef>0 && pthread_equal(p->owner, self) ){
      p->nRef++;
    }else{
      pthread_mutex_lock(&p->mutex);
      assert( p->nRef==0 );
      p->owner = self;
      p->nRef = 1;
    }
  }
#else
  /* Use the built-in recursive mutexes if they are available.
  */
  pthread_mutex_lock(&p->mutex);
  p->owner = pthread_self();
  p->nRef++;
#endif

#ifdef SQLITE_DEBUG
  if( p->trace ){
    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
  }
#endif
}
static int pthreadMutexTry(sqlite3_mutex *p){
  int rc;
  assert( p->id==SQLITE_MUTEX_RECURSIVE || pthreadMutexNotheld(p) );

#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
  /* If recursive mutexes are not available, then we have to grow
  ** our own.  This implementation assumes that pthread_equal()
  ** is atomic - that it cannot be deceived into thinking self
  ** and p->owner are equal if p->owner changes between two values
  ** that are not equal to self while the comparison is taking place.
  ** This implementation also assumes a coherent cache - that
  ** separate processes cannot read different values from the same
  ** address at the same time.  If either of these two conditions
  ** are not met, then the mutexes will fail and problems will result.
  */
  {
    pthread_t self = pthread_self();
    if( p->nRef>0 && pthread_equal(p->owner, self) ){
      p->nRef++;
      rc = SQLITE_OK;
    }else if( pthread_mutex_trylock(&p->mutex)==0 ){
      assert( p->nRef==0 );
      p->owner = self;
      p->nRef = 1;
      rc = SQLITE_OK;
    }else{
      rc = SQLITE_BUSY;
    }
  }
#else
  /* Use the built-in recursive mutexes if they are available.
  */
  if( pthread_mutex_trylock(&p->mutex)==0 ){
    p->owner = pthread_self();
    p->nRef++;
    rc = SQLITE_OK;
  }else{
    rc = SQLITE_BUSY;
  }
#endif

#ifdef SQLITE_DEBUG
  if( rc==SQLITE_OK && p->trace ){
    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
  }
#endif
  return rc;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
*/
static void pthreadMutexLeave(sqlite3_mutex *p){
  assert( pthreadMutexHeld(p) );
  p->nRef--;
  assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );

#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
  if( p->nRef==0 ){
    pthread_mutex_unlock(&p->mutex);
  }
#else
  pthread_mutex_unlock(&p->mutex);
#endif

#ifdef SQLITE_DEBUG
  if( p->trace ){
    printf("leave mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
  }
#endif
}

SQLITE_PRIVATE sqlite3_mutex_methods *sqlite3DefaultMutex(void){
  static sqlite3_mutex_methods sMutex = {
    pthreadMutexInit,
    pthreadMutexEnd,
    pthreadMutexAlloc,
    pthreadMutexFree,
    pthreadMutexEnter,
    pthreadMutexTry,
    pthreadMutexLeave,
#ifdef SQLITE_DEBUG
    pthreadMutexHeld,
    pthreadMutexNotheld
#else
    0,
    0
#endif
  };

  return &sMutex;
}

#endif /* SQLITE_MUTEX_PTHREAD */

/************** End of mutex_unix.c ******************************************/
/************** Begin file mutex_w32.c ***************************************/
/*
** 2007 August 14
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for win32
*/

/*
** The code in this file is only used if we are compiling multithreaded
** on a win32 system.
*/
#ifdef SQLITE_MUTEX_W32

/*
** Each recursive mutex is an instance of the following structure.
*/
struct sqlite3_mutex {
  CRITICAL_SECTION mutex;    /* Mutex controlling the lock */
  int id;                    /* Mutex type */
  int nRef;                  /* Number of enterances */
  DWORD owner;               /* Thread holding this mutex */
};

/*
** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,
** or WinCE.  Return false (zero) for Win95, Win98, or WinME.
**
** Here is an interesting observation:  Win95, Win98, and WinME lack
** the LockFileEx() API.  But we can still statically link against that
** API as long as we don't call it win running Win95/98/ME.  A call to
** this routine is used to determine if the host is Win95/98/ME or
** WinNT/2K/XP so that we will know whether or not we can safely call
** the LockFileEx() API.
**
** mutexIsNT() is only used for the TryEnterCriticalSection() API call,
** which is only available if your application was compiled with
** _WIN32_WINNT defined to a value >= 0x0400.  Currently, the only
** call to TryEnterCriticalSection() is #ifdef'ed out, so #ifdef
** this out as well.
*/
#if 0
#if SQLITE_OS_WINCE
# define mutexIsNT()  (1)
#else
  static int mutexIsNT(void){
    static int osType = 0;
    if( osType==0 ){
      OSVERSIONINFO sInfo;
      sInfo.dwOSVersionInfoSize = sizeof(sInfo);
      GetVersionEx(&sInfo);
      osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
    }
    return osType==2;
  }
#endif /* SQLITE_OS_WINCE */
#endif

#ifdef SQLITE_DEBUG
/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use only inside assert() statements.
*/
static int winMutexHeld(sqlite3_mutex *p){
  return p->nRef!=0 && p->owner==GetCurrentThreadId();
}
static int winMutexNotheld(sqlite3_mutex *p){
  return p->nRef==0 || p->owner!=GetCurrentThreadId();
}
#endif


/*
** Initialize and deinitialize the mutex subsystem.
*/
static sqlite3_mutex winMutex_staticMutexes[6];
static int winMutex_isInit = 0;
/* As winMutexInit() and winMutexEnd() are called as part
** of the sqlite3_initialize and sqlite3_shutdown()
** processing, the "interlocked" magic is probably not
** strictly necessary.
*/
static long winMutex_lock = 0;

static int winMutexInit(void){
  /* The first to increment to 1 does actual initialization */
  if( InterlockedCompareExchange(&winMutex_lock, 1, 0)==0 ){
    int i;
    for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
      InitializeCriticalSection(&winMutex_staticMutexes[i].mutex);
    }
    winMutex_isInit = 1;
  }else{
    /* Someone else is in the process of initing the static mutexes */
    while( !winMutex_isInit ){
      Sleep(1);
    }
  }
  return SQLITE_OK;
}

static int winMutexEnd(void){
  /* The first to decrement to 0 does actual shutdown
  ** (which should be the last to shutdown.) */
  if( InterlockedCompareExchange(&winMutex_lock, 0, 1)==1 ){
    if( winMutex_isInit==1 ){
      int i;
      for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
        DeleteCriticalSection(&winMutex_staticMutexes[i].mutex);
      }
      winMutex_isInit = 0;
    }
  }
  return SQLITE_OK;
}

/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated.  SQLite
** will unwind its stack and return an error.  The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li>  SQLITE_MUTEX_FAST
** <li>  SQLITE_MUTEX_RECURSIVE
** <li>  SQLITE_MUTEX_STATIC_MASTER
** <li>  SQLITE_MUTEX_STATIC_MEM
** <li>  SQLITE_MUTEX_STATIC_MEM2
** <li>  SQLITE_MUTEX_STATIC_PRNG
** <li>  SQLITE_MUTEX_STATIC_LRU
** <li>  SQLITE_MUTEX_STATIC_LRU2
** </ul>
**
** The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
** not want to.  But SQLite will only request a recursive mutex in
** cases where it really needs one.  If a faster non-recursive mutex
** implementation is available on the host platform, the mutex subsystem
** might return such a mutex in response to SQLITE_MUTEX_FAST.
**
** The other allowed parameters to sqlite3_mutex_alloc() each return
** a pointer to a static preexisting mutex.  Six static mutexes are
** used by the current version of SQLite.  Future versions of SQLite
** may add additional static mutexes.  Static mutexes are for internal
** use by SQLite only.  Applications that use SQLite mutexes should
** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
** SQLITE_MUTEX_RECURSIVE.
**
** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
** returns a different mutex on every call.  But for the static
** mutex types, the same mutex is returned on every call that has
** the same type number.
*/
static sqlite3_mutex *winMutexAlloc(int iType){
  sqlite3_mutex *p;

  switch( iType ){
    case SQLITE_MUTEX_FAST:
    case SQLITE_MUTEX_RECURSIVE: {
      p = sqlite3MallocZero( sizeof(*p) );
      if( p ){
        p->id = iType;
        InitializeCriticalSection(&p->mutex);
      }
      break;
    }
    default: {
      assert( winMutex_isInit==1 );
      assert( iType-2 >= 0 );
      assert( iType-2 < ArraySize(winMutex_staticMutexes) );
      p = &winMutex_staticMutexes[iType-2];
      p->id = iType;
      break;
    }
  }
  return p;
}


/*
** This routine deallocates a previously
** allocated mutex.  SQLite is careful to deallocate every
** mutex that it allocates.
*/
static void winMutexFree(sqlite3_mutex *p){
  assert( p );
  assert( p->nRef==0 );
  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
  DeleteCriticalSection(&p->mutex);
  sqlite3_free(p);
}

/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void winMutexEnter(sqlite3_mutex *p){
  assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld(p) );
  EnterCriticalSection(&p->mutex);
  p->owner = GetCurrentThreadId();
  p->nRef++;
}
static int winMutexTry(sqlite3_mutex *p){
  int rc = SQLITE_BUSY;
  assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld(p) );
  /*
  ** The sqlite3_mutex_try() routine is very rarely used, and when it
  ** is used it is merely an optimization.  So it is OK for it to always
  ** fail.
  **
  ** The TryEnterCriticalSection() interface is only available on WinNT.
  ** And some windows compilers complain if you try to use it without
  ** first doing some #defines that prevent SQLite from building on Win98.
  ** For that reason, we will omit this optimization for now.  See
  ** ticket #2685.
  */
#if 0
  if( mutexIsNT() && TryEnterCriticalSection(&p->mutex) ){
    p->owner = GetCurrentThreadId();
    p->nRef++;
    rc = SQLITE_OK;
  }
#else
  UNUSED_PARAMETER(p);
#endif
  return rc;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
*/
static void winMutexLeave(sqlite3_mutex *p){
  assert( p->nRef>0 );
  assert( p->owner==GetCurrentThreadId() );
  p->nRef--;
  assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
  LeaveCriticalSection(&p->mutex);
}

SQLITE_PRIVATE sqlite3_mutex_methods *sqlite3DefaultMutex(void){
  static sqlite3_mutex_methods sMutex = {
    winMutexInit,
    winMutexEnd,
    winMutexAlloc,
    winMutexFree,
    winMutexEnter,
    winMutexTry,
    winMutexLeave,
#ifdef SQLITE_DEBUG
    winMutexHeld,
    winMutexNotheld
#else
    0,
    0
#endif
  };

  return &sMutex;
}
#endif /* SQLITE_MUTEX_W32 */

/************** End of mutex_w32.c *******************************************/
/************** Begin file malloc.c ******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** Memory allocation functions used throughout sqlite.
*/

/*
** This routine runs when the memory allocator sees that the
** total memory allocation is about to exceed the soft heap
** limit.
*/
static void softHeapLimitEnforcer(
  void *NotUsed,
  sqlite3_int64 NotUsed2,
  int allocSize
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  sqlite3_release_memory(allocSize);
}

/*
** Set the soft heap-size limit for the library. Passing a zero or
** negative value indicates no limit.
*/
SQLITE_API void sqlite3_soft_heap_limit(int n){
  sqlite3_uint64 iLimit;
  int overage;
  if( n<0 ){
    iLimit = 0;
  }else{
    iLimit = n;
  }
#ifndef SQLITE_OMIT_AUTOINIT
  sqlite3_initialize();
#endif
  if( iLimit>0 ){
    sqlite3MemoryAlarm(softHeapLimitEnforcer, 0, iLimit);
  }else{
    sqlite3MemoryAlarm(0, 0, 0);
  }
  overage = (int)(sqlite3_memory_used() - (i64)n);
  if( overage>0 ){
    sqlite3_release_memory(overage);
  }
}

/*
** Attempt to release up to n bytes of non-essential memory currently
** held by SQLite. An example of non-essential memory is memory used to
** cache database pages that are not currently in use.
*/
SQLITE_API int sqlite3_release_memory(int n){
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  int nRet = 0;
  nRet += sqlite3PcacheReleaseMemory(n-nRet);
  return nRet;
#else
  UNUSED_PARAMETER(n);
  return SQLITE_OK;
#endif
}

/*
** State information local to the memory allocation subsystem.
*/
static SQLITE_WSD struct Mem0Global {
  /* Number of free pages for scratch and page-cache memory */
  u32 nScratchFree;
  u32 nPageFree;

  sqlite3_mutex *mutex;         /* Mutex to serialize access */

  /*
  ** The alarm callback and its arguments.  The mem0.mutex lock will
  ** be held while the callback is running.  Recursive calls into
  ** the memory subsystem are allowed, but no new callbacks will be
  ** issued.
  */
  sqlite3_int64 alarmThreshold;
  void (*alarmCallback)(void*, sqlite3_int64,int);
  void *alarmArg;

  /*
  ** Pointers to the end of sqlite3GlobalConfig.pScratch and
  ** sqlite3GlobalConfig.pPage to a block of memory that records
  ** which pages are available.
  */
  u32 *aScratchFree;
  u32 *aPageFree;
} mem0 = { 0, 0, 0, 0, 0, 0, 0, 0 };

#define mem0 GLOBAL(struct Mem0Global, mem0)

/*
** Initialize the memory allocation subsystem.
*/
SQLITE_PRIVATE int sqlite3MallocInit(void){
  if( sqlite3GlobalConfig.m.xMalloc==0 ){
    sqlite3MemSetDefault();
  }
  memset(&mem0, 0, sizeof(mem0));
  if( sqlite3GlobalConfig.bCoreMutex ){
    mem0.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
  }
  if( sqlite3GlobalConfig.pScratch && sqlite3GlobalConfig.szScratch>=100
      && sqlite3GlobalConfig.nScratch>=0 ){
    int i;
    sqlite3GlobalConfig.szScratch = ROUNDDOWN8(sqlite3GlobalConfig.szScratch-4);
    mem0.aScratchFree = (u32*)&((char*)sqlite3GlobalConfig.pScratch)
                  [sqlite3GlobalConfig.szScratch*sqlite3GlobalConfig.nScratch];
    for(i=0; i<sqlite3GlobalConfig.nScratch; i++){ mem0.aScratchFree[i] = i; }
    mem0.nScratchFree = sqlite3GlobalConfig.nScratch;
  }else{
    sqlite3GlobalConfig.pScratch = 0;
    sqlite3GlobalConfig.szScratch = 0;
  }
  if( sqlite3GlobalConfig.pPage && sqlite3GlobalConfig.szPage>=512
      && sqlite3GlobalConfig.nPage>=1 ){
    int i;
    int overhead;
    int sz = ROUNDDOWN8(sqlite3GlobalConfig.szPage);
    int n = sqlite3GlobalConfig.nPage;
    overhead = (4*n + sz - 1)/sz;
    sqlite3GlobalConfig.nPage -= overhead;
    mem0.aPageFree = (u32*)&((char*)sqlite3GlobalConfig.pPage)
                  [sqlite3GlobalConfig.szPage*sqlite3GlobalConfig.nPage];
    for(i=0; i<sqlite3GlobalConfig.nPage; i++){ mem0.aPageFree[i] = i; }
    mem0.nPageFree = sqlite3GlobalConfig.nPage;
  }else{
    sqlite3GlobalConfig.pPage = 0;
    sqlite3GlobalConfig.szPage = 0;
  }
  return sqlite3GlobalConfig.m.xInit(sqlite3GlobalConfig.m.pAppData);
}

/*
** Deinitialize the memory allocation subsystem.
*/
SQLITE_PRIVATE void sqlite3MallocEnd(void){
  if( sqlite3GlobalConfig.m.xShutdown ){
    sqlite3GlobalConfig.m.xShutdown(sqlite3GlobalConfig.m.pAppData);
  }
  memset(&mem0, 0, sizeof(mem0));
}

/*
** Return the amount of memory currently checked out.
*/
SQLITE_API sqlite3_int64 sqlite3_memory_used(void){
  int n, mx;
  sqlite3_int64 res;
  sqlite3_status(SQLITE_STATUS_MEMORY_USED, &n, &mx, 0);
  res = (sqlite3_int64)n;  /* Work around bug in Borland C. Ticket #3216 */
  return res;
}

/*
** Return the maximum amount of memory that has ever been
** checked out since either the beginning of this process
** or since the most recent reset.
*/
SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag){
  int n, mx;
  sqlite3_int64 res;
  sqlite3_status(SQLITE_STATUS_MEMORY_USED, &n, &mx, resetFlag);
  res = (sqlite3_int64)mx;  /* Work around bug in Borland C. Ticket #3216 */
  return res;
}

/*
** Change the alarm callback
*/
SQLITE_PRIVATE int sqlite3MemoryAlarm(
  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
  void *pArg,
  sqlite3_int64 iThreshold
){
  sqlite3_mutex_enter(mem0.mutex);
  mem0.alarmCallback = xCallback;
  mem0.alarmArg = pArg;
  mem0.alarmThreshold = iThreshold;
  sqlite3_mutex_leave(mem0.mutex);
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_DEPRECATED
/*
** Deprecated external interface.  Internal/core SQLite code
** should call sqlite3MemoryAlarm.
*/
SQLITE_API int sqlite3_memory_alarm(
  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
  void *pArg,
  sqlite3_int64 iThreshold
){
  return sqlite3MemoryAlarm(xCallback, pArg, iThreshold);
}
#endif

/*
** Trigger the alarm
*/
static void sqlite3MallocAlarm(int nByte){
  void (*xCallback)(void*,sqlite3_int64,int);
  sqlite3_int64 nowUsed;
  void *pArg;
  if( mem0.alarmCallback==0 ) return;
  xCallback = mem0.alarmCallback;
  nowUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
  pArg = mem0.alarmArg;
  mem0.alarmCallback = 0;
  sqlite3_mutex_leave(mem0.mutex);
  xCallback(pArg, nowUsed, nByte);
  sqlite3_mutex_enter(mem0.mutex);
  mem0.alarmCallback = xCallback;
  mem0.alarmArg = pArg;
}

/*
** Do a memory allocation with statistics and alarms.  Assume the
** lock is already held.
*/
static int mallocWithAlarm(int n, void **pp){
  int nFull;
  void *p;
  assert( sqlite3_mutex_held(mem0.mutex) );
  nFull = sqlite3GlobalConfig.m.xRoundup(n);
  sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, n);
  if( mem0.alarmCallback!=0 ){
    int nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
    if( nUsed+nFull >= mem0.alarmThreshold ){
      sqlite3MallocAlarm(nFull);
    }
  }
  p = sqlite3GlobalConfig.m.xMalloc(nFull);
  if( p==0 && mem0.alarmCallback ){
    sqlite3MallocAlarm(nFull);
    p = sqlite3GlobalConfig.m.xMalloc(nFull);
  }
  if( p ){
    nFull = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, nFull);
  }
  *pp = p;
  return nFull;
}

/*
** Allocate memory.  This routine is like sqlite3_malloc() except that it
** assumes the memory subsystem has already been initialized.
*/
SQLITE_PRIVATE void *sqlite3Malloc(int n){
  void *p;
  if( n<=0 || n>=0x7fffff00 ){
    /* A memory allocation of a number of bytes which is near the maximum
    ** signed integer value might cause an integer overflow inside of the
    ** xMalloc().  Hence we limit the maximum size to 0x7fffff00, giving
    ** 255 bytes of overhead.  SQLite itself will never use anything near
    ** this amount.  The only way to reach the limit is with sqlite3_malloc() */
    p = 0;
  }else if( sqlite3GlobalConfig.bMemstat ){
    sqlite3_mutex_enter(mem0.mutex);
    mallocWithAlarm(n, &p);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    p = sqlite3GlobalConfig.m.xMalloc(n);
  }
  return p;
}

/*
** This version of the memory allocation is for use by the application.
** First make sure the memory subsystem is initialized, then do the
** allocation.
*/
SQLITE_API void *sqlite3_malloc(int n){
#ifndef SQLITE_OMIT_AUTOINIT
  if( sqlite3_initialize() ) return 0;
#endif
  return sqlite3Malloc(n);
}

/*
** Each thread may only have a single outstanding allocation from
** xScratchMalloc().  We verify this constraint in the single-threaded
** case by setting scratchAllocOut to 1 when an allocation
** is outstanding clearing it when the allocation is freed.
*/
#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
static int scratchAllocOut = 0;
#endif


/*
** Allocate memory that is to be used and released right away.
** This routine is similar to alloca() in that it is not intended
** for situations where the memory might be held long-term.  This
** routine is intended to get memory to old large transient data
** structures that would not normally fit on the stack of an
** embedded processor.
*/
SQLITE_PRIVATE void *sqlite3ScratchMalloc(int n){
  void *p;
  assert( n>0 );

#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
  /* Verify that no more than one scratch allocation per thread
  ** is outstanding at one time.  (This is only checked in the
  ** single-threaded case since checking in the multi-threaded case
  ** would be much more complicated.) */
  assert( scratchAllocOut==0 );
#endif

  if( sqlite3GlobalConfig.szScratch<n ){
    goto scratch_overflow;
  }else{
    sqlite3_mutex_enter(mem0.mutex);
    if( mem0.nScratchFree==0 ){
      sqlite3_mutex_leave(mem0.mutex);
      goto scratch_overflow;
    }else{
      int i;
      i = mem0.aScratchFree[--mem0.nScratchFree];
      i *= sqlite3GlobalConfig.szScratch;
      sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, 1);
      sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
      sqlite3_mutex_leave(mem0.mutex);
      p = (void*)&((char*)sqlite3GlobalConfig.pScratch)[i];
      assert(  (((u8*)p - (u8*)0) & 7)==0 );
    }
  }
#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
  scratchAllocOut = p!=0;
#endif

  return p;

scratch_overflow:
  if( sqlite3GlobalConfig.bMemstat ){
    sqlite3_mutex_enter(mem0.mutex);
    sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
    n = mallocWithAlarm(n, &p);
    if( p ) sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, n);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    p = sqlite3GlobalConfig.m.xMalloc(n);
  }
#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
  scratchAllocOut = p!=0;
#endif
  return p;
}
SQLITE_PRIVATE void sqlite3ScratchFree(void *p){
  if( p ){

#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
    /* Verify that no more than one scratch allocation per thread
    ** is outstanding at one time.  (This is only checked in the
    ** single-threaded case since checking in the multi-threaded case
    ** would be much more complicated.) */
    assert( scratchAllocOut==1 );
    scratchAllocOut = 0;
#endif

    if( sqlite3GlobalConfig.pScratch==0
           || p<sqlite3GlobalConfig.pScratch
           || p>=(void*)mem0.aScratchFree ){
      if( sqlite3GlobalConfig.bMemstat ){
        int iSize = sqlite3MallocSize(p);
        sqlite3_mutex_enter(mem0.mutex);
        sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, -iSize);
        sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, -iSize);
        sqlite3GlobalConfig.m.xFree(p);
        sqlite3_mutex_leave(mem0.mutex);
      }else{
        sqlite3GlobalConfig.m.xFree(p);
      }
    }else{
      int i;
      i = (int)((u8*)p - (u8*)sqlite3GlobalConfig.pScratch);
      i /= sqlite3GlobalConfig.szScratch;
      assert( i>=0 && i<sqlite3GlobalConfig.nScratch );
      sqlite3_mutex_enter(mem0.mutex);
      assert( mem0.nScratchFree<(u32)sqlite3GlobalConfig.nScratch );
      mem0.aScratchFree[mem0.nScratchFree++] = i;
      sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, -1);
      sqlite3_mutex_leave(mem0.mutex);
    }
  }
}

/*
** TRUE if p is a lookaside memory allocation from db
*/
#ifndef SQLITE_OMIT_LOOKASIDE
static int isLookaside(sqlite3 *db, void *p){
  return db && p && p>=db->lookaside.pStart && p<db->lookaside.pEnd;
}
#else
#define isLookaside(A,B) 0
#endif

/*
** Return the size of a memory allocation previously obtained from
** sqlite3Malloc() or sqlite3_malloc().
*/
SQLITE_PRIVATE int sqlite3MallocSize(void *p){
  return sqlite3GlobalConfig.m.xSize(p);
}
SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3 *db, void *p){
  assert( db==0 || sqlite3_mutex_held(db->mutex) );
  if( isLookaside(db, p) ){
    return db->lookaside.sz;
  }else{
    return sqlite3GlobalConfig.m.xSize(p);
  }
}

/*
** Free memory previously obtained from sqlite3Malloc().
*/
SQLITE_API void sqlite3_free(void *p){
  if( p==0 ) return;
  if( sqlite3GlobalConfig.bMemstat ){
    sqlite3_mutex_enter(mem0.mutex);
    sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, -sqlite3MallocSize(p));
    sqlite3GlobalConfig.m.xFree(p);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    sqlite3GlobalConfig.m.xFree(p);
  }
}

/*
** Free memory that might be associated with a particular database
** connection.
*/
SQLITE_PRIVATE void sqlite3DbFree(sqlite3 *db, void *p){
  assert( db==0 || sqlite3_mutex_held(db->mutex) );
  if( isLookaside(db, p) ){
    LookasideSlot *pBuf = (LookasideSlot*)p;
    pBuf->pNext = db->lookaside.pFree;
    db->lookaside.pFree = pBuf;
    db->lookaside.nOut--;
  }else{
    sqlite3_free(p);
  }
}

/*
** Change the size of an existing memory allocation
*/
SQLITE_PRIVATE void *sqlite3Realloc(void *pOld, int nBytes){
  int nOld, nNew;
  void *pNew;
  if( pOld==0 ){
    return sqlite3Malloc(nBytes);
  }
  if( nBytes<=0 ){
    sqlite3_free(pOld);
    return 0;
  }
  if( nBytes>=0x7fffff00 ){
    /* The 0x7ffff00 limit term is explained in comments on sqlite3Malloc() */
    return 0;
  }
  nOld = sqlite3MallocSize(pOld);
  nNew = sqlite3GlobalConfig.m.xRoundup(nBytes);
  if( nOld==nNew ){
    pNew = pOld;
  }else if( sqlite3GlobalConfig.bMemstat ){
    sqlite3_mutex_enter(mem0.mutex);
    sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, nBytes);
    if( sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED)+nNew-nOld >=
          mem0.alarmThreshold ){
      sqlite3MallocAlarm(nNew-nOld);
    }
    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
    if( pNew==0 && mem0.alarmCallback ){
      sqlite3MallocAlarm(nBytes);
      pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
    }
    if( pNew ){
      nNew = sqlite3MallocSize(pNew);
      sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, nNew-nOld);
    }
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
  }
  return pNew;
}

/*
** The public interface to sqlite3Realloc.  Make sure that the memory
** subsystem is initialized prior to invoking sqliteRealloc.
*/
SQLITE_API void *sqlite3_realloc(void *pOld, int n){
#ifndef SQLITE_OMIT_AUTOINIT
  if( sqlite3_initialize() ) return 0;
#endif
  return sqlite3Realloc(pOld, n);
}


/*
** Allocate and zero memory.
*/
SQLITE_PRIVATE void *sqlite3MallocZero(int n){
  void *p = sqlite3Malloc(n);
  if( p ){
    memset(p, 0, n);
  }
  return p;
}

/*
** Allocate and zero memory.  If the allocation fails, make
** the mallocFailed flag in the connection pointer.
*/
SQLITE_PRIVATE void *sqlite3DbMallocZero(sqlite3 *db, int n){
  void *p = sqlite3DbMallocRaw(db, n);
  if( p ){
    memset(p, 0, n);
  }
  return p;
}

/*
** Allocate and zero memory.  If the allocation fails, make
** the mallocFailed flag in the connection pointer.
**
** If db!=0 and db->mallocFailed is true (indicating a prior malloc
** failure on the same database connection) then always return 0.
** Hence for a particular database connection, once malloc starts
** failing, it fails consistently until mallocFailed is reset.
** This is an important assumption.  There are many places in the
** code that do things like this:
**
**         int *a = (int*)sqlite3DbMallocRaw(db, 100);
**         int *b = (int*)sqlite3DbMallocRaw(db, 200);
**         if( b ) a[10] = 9;
**
** In other words, if a subsequent malloc (ex: "b") worked, it is assumed
** that all prior mallocs (ex: "a") worked too.
*/
SQLITE_PRIVATE void *sqlite3DbMallocRaw(sqlite3 *db, int n){
  void *p;
  assert( db==0 || sqlite3_mutex_held(db->mutex) );
#ifndef SQLITE_OMIT_LOOKASIDE
  if( db ){
    LookasideSlot *pBuf;
    if( db->mallocFailed ){
      return 0;
    }
    if( db->lookaside.bEnabled && n<=db->lookaside.sz
         && (pBuf = db->lookaside.pFree)!=0 ){
      db->lookaside.pFree = pBuf->pNext;
      db->lookaside.nOut++;
      if( db->lookaside.nOut>db->lookaside.mxOut ){
        db->lookaside.mxOut = db->lookaside.nOut;
      }
      return (void*)pBuf;
    }
  }
#else
  if( db && db->mallocFailed ){
    return 0;
  }
#endif
  p = sqlite3Malloc(n);
  if( !p && db ){
    db->mallocFailed = 1;
  }
  return p;
}

/*
** Resize the block of memory pointed to by p to n bytes. If the
** resize fails, set the mallocFailed flag in the connection object.
*/
SQLITE_PRIVATE void *sqlite3DbRealloc(sqlite3 *db, void *p, int n){
  void *pNew = 0;
  assert( db!=0 );
  assert( sqlite3_mutex_held(db->mutex) );
  if( db->mallocFailed==0 ){
    if( p==0 ){
      return sqlite3DbMallocRaw(db, n);
    }
    if( isLookaside(db, p) ){
      if( n<=db->lookaside.sz ){
        return p;
      }
      pNew = sqlite3DbMallocRaw(db, n);
      if( pNew ){
        memcpy(pNew, p, db->lookaside.sz);
        sqlite3DbFree(db, p);
      }
    }else{
      pNew = sqlite3_realloc(p, n);
      if( !pNew ){
        db->mallocFailed = 1;
      }
    }
  }
  return pNew;
}

/*
** Attempt to reallocate p.  If the reallocation fails, then free p
** and set the mallocFailed flag in the database connection.
*/
SQLITE_PRIVATE void *sqlite3DbReallocOrFree(sqlite3 *db, void *p, int n){
  void *pNew;
  pNew = sqlite3DbRealloc(db, p, n);
  if( !pNew ){
    sqlite3DbFree(db, p);
  }
  return pNew;
}

/*
** Make a copy of a string in memory obtained from sqliteMalloc(). These
** functions call sqlite3MallocRaw() directly instead of sqliteMalloc(). This
** is because when memory debugging is turned on, these two functions are
** called via macros that record the current file and line number in the
** ThreadData structure.
*/
SQLITE_PRIVATE char *sqlite3DbStrDup(sqlite3 *db, const char *z){
  char *zNew;
  size_t n;
  if( z==0 ){
    return 0;
  }
  n = sqlite3Strlen30(z) + 1;
  assert( (n&0x7fffffff)==n );
  zNew = sqlite3DbMallocRaw(db, (int)n);
  if( zNew ){
    memcpy(zNew, z, n);
  }
  return zNew;
}
SQLITE_PRIVATE char *sqlite3DbStrNDup(sqlite3 *db, const char *z, int n){
  char *zNew;
  if( z==0 ){
    return 0;
  }
  assert( (n&0x7fffffff)==n );
  zNew = sqlite3DbMallocRaw(db, n+1);
  if( zNew ){
    memcpy(zNew, z, n);
    zNew[n] = 0;
  }
  return zNew;
}

/*
** Create a string from the zFromat argument and the va_list that follows.
** Store the string in memory obtained from sqliteMalloc() and make *pz
** point to that string.
*/
SQLITE_PRIVATE void sqlite3SetString(char **pz, sqlite3 *db, const char *zFormat, ...){
  va_list ap;
  char *z;

  va_start(ap, zFormat);
  z = sqlite3VMPrintf(db, zFormat, ap);
  va_end(ap);
  sqlite3DbFree(db, *pz);
  *pz = z;
}


/*
** This function must be called before exiting any API function (i.e.
** returning control to the user) that has called sqlite3_malloc or
** sqlite3_realloc.
**
** The returned value is normally a copy of the second argument to this
** function. However, if a malloc() failure has occurred since the previous
** invocation SQLITE_NOMEM is returned instead.
**
** If the first argument, db, is not NULL and a malloc() error has occurred,
** then the connection error-code (the value returned by sqlite3_errcode())
** is set to SQLITE_NOMEM.
*/
SQLITE_PRIVATE int sqlite3ApiExit(sqlite3* db, int rc){
  /* If the db handle is not NULL, then we must hold the connection handle
  ** mutex here. Otherwise the read (and possible write) of db->mallocFailed
  ** is unsafe, as is the call to sqlite3Error().
  */
  assert( !db || sqlite3_mutex_held(db->mutex) );
  if( db && (db->mallocFailed || rc==SQLITE_IOERR_NOMEM) ){
    sqlite3Error(db, SQLITE_NOMEM, 0);
    db->mallocFailed = 0;
    rc = SQLITE_NOMEM;
  }
  return rc & (db ? db->errMask : 0xff);
}

/************** End of malloc.c **********************************************/
/************** Begin file printf.c ******************************************/
/*
** The "printf" code that follows dates from the 1980's.  It is in
** the public domain.  The original comments are included here for
** completeness.  They are very out-of-date but might be useful as
** an historical reference.  Most of the "enhancements" have been backed
** out so that the functionality is now the same as standard printf().
**
**************************************************************************
**
** The following modules is an enhanced replacement for the "printf" subroutines
** found in the standard C library.  The following enhancements are
** supported:
**
**      +  Additional functions.  The standard set of "printf" functions
**         includes printf, fprintf, sprintf, vprintf, vfprintf, and
**         vsprintf.  This module adds the following:
**
**           *  snprintf -- Works like sprintf, but has an extra argument
**                          which is the size of the buffer written to.
**
**           *  mprintf --  Similar to sprintf.  Writes output to memory
**                          obtained from malloc.
**
**           *  xprintf --  Calls a function to dispose of output.
**
**           *  nprintf --  No output, but returns the number of characters
**                          that would have been output by printf.
**
**           *  A v- version (ex: vsnprintf) of every function is also
**              supplied.
**
**      +  A few extensions to the formatting notation are supported:
**
**           *  The "=" flag (similar to "-") causes the output to be
**              be centered in the appropriately sized field.
**
**           *  The %b field outputs an integer in binary notation.
**
**           *  The %c field now accepts a precision.  The character output
**              is repeated by the number of times the precision specifies.
**
**           *  The %' field works like %c, but takes as its character the
**              next character of the format string, instead of the next
**              argument.  For example,  printf("%.78'-")  prints 78 minus
**              signs, the same as  printf("%.78c",'-').
**
**      +  When compiled using GCC on a SPARC, this version of printf is
**         faster than the library printf for SUN OS 4.1.
**
**      +  All functions are fully reentrant.
**
*/

/*
** Conversion types fall into various categories as defined by the
** following enumeration.
*/
#define etRADIX       1 /* Integer types.  %d, %x, %o, and so forth */
#define etFLOAT       2 /* Floating point.  %f */
#define etEXP         3 /* Exponentional notation. %e and %E */
#define etGENERIC     4 /* Floating or exponential, depending on exponent. %g */
#define etSIZE        5 /* Return number of characters processed so far. %n */
#define etSTRING      6 /* Strings. %s */
#define etDYNSTRING   7 /* Dynamically allocated strings. %z */
#define etPERCENT     8 /* Percent symbol. %% */
#define etCHARX       9 /* Characters. %c */
/* The rest are extensions, not normally found in printf() */
#define etSQLESCAPE  10 /* Strings with '\'' doubled.  %q */
#define etSQLESCAPE2 11 /* Strings with '\'' doubled and enclosed in '',
                          NULL pointers replaced by SQL NULL.  %Q */
#define etTOKEN      12 /* a pointer to a Token structure */
#define etSRCLIST    13 /* a pointer to a SrcList */
#define etPOINTER    14 /* The %p conversion */
#define etSQLESCAPE3 15 /* %w -> Strings with '\"' doubled */
#define etORDINAL    16 /* %r -> 1st, 2nd, 3rd, 4th, etc.  English only */

#define etINVALID     0 /* Any unrecognized conversion type */


/*
** An "etByte" is an 8-bit unsigned value.
*/
typedef unsigned char etByte;

/*
** Each builtin conversion character (ex: the 'd' in "%d") is described
** by an instance of the following structure
*/
typedef struct et_info {   /* Information about each format field */
  char fmttype;            /* The format field code letter */
  etByte base;             /* The base for radix conversion */
  etByte flags;            /* One or more of FLAG_ constants below */
  etByte type;             /* Conversion paradigm */
  etByte charset;          /* Offset into aDigits[] of the digits string */
  etByte prefix;           /* Offset into aPrefix[] of the prefix string */
} et_info;

/*
** Allowed values for et_info.flags
*/
#define FLAG_SIGNED  1     /* True if the value to convert is signed */
#define FLAG_INTERN  2     /* True if for internal use only */
#define FLAG_STRING  4     /* Allow infinity precision */


/*
** The following table is searched linearly, so it is good to put the
** most frequently used conversion types first.
*/
static const char aDigits[] = "0123456789ABCDEF0123456789abcdef";
static const char aPrefix[] = "-x0\000X0";
static const et_info fmtinfo[] = {
  {  'd', 10, 1, etRADIX,      0,  0 },
  {  's',  0, 4, etSTRING,     0,  0 },
  {  'g',  0, 1, etGENERIC,    30, 0 },
  {  'z',  0, 4, etDYNSTRING,  0,  0 },
  {  'q',  0, 4, etSQLESCAPE,  0,  0 },
  {  'Q',  0, 4, etSQLESCAPE2, 0,  0 },
  {  'w',  0, 4, etSQLESCAPE3, 0,  0 },
  {  'c',  0, 0, etCHARX,      0,  0 },
  {  'o',  8, 0, etRADIX,      0,  2 },
  {  'u', 10, 0, etRADIX,      0,  0 },
  {  'x', 16, 0, etRADIX,      16, 1 },
  {  'X', 16, 0, etRADIX,      0,  4 },
#ifndef SQLITE_OMIT_FLOATING_POINT
  {  'f',  0, 1, etFLOAT,      0,  0 },
  {  'e',  0, 1, etEXP,        30, 0 },
  {  'E',  0, 1, etEXP,        14, 0 },
  {  'G',  0, 1, etGENERIC,    14, 0 },
#endif
  {  'i', 10, 1, etRADIX,      0,  0 },
  {  'n',  0, 0, etSIZE,       0,  0 },
  {  '%',  0, 0, etPERCENT,    0,  0 },
  {  'p', 16, 0, etPOINTER,    0,  1 },

/* All the rest have the FLAG_INTERN bit set and are thus for internal
** use only */
  {  'T',  0, 2, etTOKEN,      0,  0 },
  {  'S',  0, 2, etSRCLIST,    0,  0 },
  {  'r', 10, 3, etORDINAL,    0,  0 },
};

/*
** If SQLITE_OMIT_FLOATING_POINT is defined, then none of the floating point
** conversions will work.
*/
#ifndef SQLITE_OMIT_FLOATING_POINT
/*
** "*val" is a double such that 0.1 <= *val < 10.0
** Return the ascii code for the leading digit of *val, then
** multiply "*val" by 10.0 to renormalize.
**
** Example:
**     input:     *val = 3.14159
**     output:    *val = 1.4159    function return = '3'
**
** The counter *cnt is incremented each time.  After counter exceeds
** 16 (the number of significant digits in a 64-bit float) '0' is
** always returned.
*/
static char et_getdigit(LONGDOUBLE_TYPE *val, int *cnt){
  int digit;
  LONGDOUBLE_TYPE d;
  if( (*cnt)++ >= 16 ) return '0';
  digit = (int)*val;
  d = digit;
  digit += '0';
  *val = (*val - d)*10.0;
  return (char)digit;
}
#endif /* SQLITE_OMIT_FLOATING_POINT */

/*
** Append N space characters to the given string buffer.
*/
static void appendSpace(StrAccum *pAccum, int N){
  static const char zSpaces[] = "                             ";
  while( N>=(int)sizeof(zSpaces)-1 ){
    sqlite3StrAccumAppend(pAccum, zSpaces, sizeof(zSpaces)-1);
    N -= sizeof(zSpaces)-1;
  }
  if( N>0 ){
    sqlite3StrAccumAppend(pAccum, zSpaces, N);
  }
}

/*
** On machines with a small stack size, you can redefine the
** SQLITE_PRINT_BUF_SIZE to be less than 350.
*/
#ifndef SQLITE_PRINT_BUF_SIZE
# if defined(SQLITE_SMALL_STACK)
#   define SQLITE_PRINT_BUF_SIZE 50
# else
#   define SQLITE_PRINT_BUF_SIZE 350
# endif
#endif
#define etBUFSIZE SQLITE_PRINT_BUF_SIZE  /* Size of the output buffer */

/*
** The root program.  All variations call this core.
**
** INPUTS:
**   func   This is a pointer to a function taking three arguments
**            1. A pointer to anything.  Same as the "arg" parameter.
**            2. A pointer to the list of characters to be output
**               (Note, this list is NOT null terminated.)
**            3. An integer number of characters to be output.
**               (Note: This number might be zero.)
**
**   arg    This is the pointer to anything which will be passed as the
**          first argument to "func".  Use it for whatever you like.
**
**   fmt    This is the format string, as in the usual print.
**
**   ap     This is a pointer to a list of arguments.  Same as in
**          vfprint.
**
** OUTPUTS:
**          The return value is the total number of characters sent to
**          the function "func".  Returns -1 on a error.
**
** Note that the order in which automatic variables are declared below
** seems to make a big difference in determining how fast this beast
** will run.
*/
SQLITE_PRIVATE void sqlite3VXPrintf(
  StrAccum *pAccum,                  /* Accumulate results here */
  int useExtended,                   /* Allow extended %-conversions */
  const char *fmt,                   /* Format string */
  va_list ap                         /* arguments */
){
  int c;                     /* Next character in the format string */
  char *bufpt;               /* Pointer to the conversion buffer */
  int precision;             /* Precision of the current field */
  int length;                /* Length of the field */
  int idx;                   /* A general purpose loop counter */
  int width;                 /* Width of the current field */
  etByte flag_leftjustify;   /* True if "-" flag is present */
  etByte flag_plussign;      /* True if "+" flag is present */
  etByte flag_blanksign;     /* True if " " flag is present */
  etByte flag_alternateform; /* True if "#" flag is present */
  etByte flag_altform2;      /* True if "!" flag is present */
  etByte flag_zeropad;       /* True if field width constant starts with zero */
  etByte flag_long;          /* True if "l" flag is present */
  etByte flag_longlong;      /* True if the "ll" flag is present */
  etByte done;               /* Loop termination flag */
  sqlite_uint64 longvalue;   /* Value for integer types */
  LONGDOUBLE_TYPE realvalue; /* Value for real types */
  const et_info *infop;      /* Pointer to the appropriate info structure */
  char buf[etBUFSIZE];       /* Conversion buffer */
  char prefix;               /* Prefix character.  "+" or "-" or " " or '\0'. */
  etByte xtype = 0;          /* Conversion paradigm */
  char *zExtra;              /* Extra memory used for etTCLESCAPE conversions */
#ifndef SQLITE_OMIT_FLOATING_POINT
  int  exp, e2;              /* exponent of real numbers */
  double rounder;            /* Used for rounding floating point values */
  etByte flag_dp;            /* True if decimal point should be shown */
  etByte flag_rtz;           /* True if trailing zeros should be removed */
  etByte flag_exp;           /* True to force display of the exponent */
  int nsd;                   /* Number of significant digits returned */
#endif

  length = 0;
  bufpt = 0;
  for(; (c=(*fmt))!=0; ++fmt){
    if( c!='%' ){
      int amt;
      bufpt = (char *)fmt;
      amt = 1;
      while( (c=(*++fmt))!='%' && c!=0 ) amt++;
      sqlite3StrAccumAppend(pAccum, bufpt, amt);
      if( c==0 ) break;
    }
    if( (c=(*++fmt))==0 ){
      sqlite3StrAccumAppend(pAccum, "%", 1);
      break;
    }
    /* Find out what flags are present */
    flag_leftjustify = flag_plussign = flag_blanksign =
     flag_alternateform = flag_altform2 = flag_zeropad = 0;
    done = 0;
    do{
      switch( c ){
        case '-':   flag_leftjustify = 1;     break;
        case '+':   flag_plussign = 1;        break;
        case ' ':   flag_blanksign = 1;       break;
        case '#':   flag_alternateform = 1;   break;
        case '!':   flag_altform2 = 1;        break;
        case '0':   flag_zeropad = 1;         break;
        default:    done = 1;                 break;
      }
    }while( !done && (c=(*++fmt))!=0 );
    /* Get the field width */
    width = 0;
    if( c=='*' ){
      width = va_arg(ap,int);
      if( width<0 ){
        flag_leftjustify = 1;
        width = -width;
      }
      c = *++fmt;
    }else{
      while( c>='0' && c<='9' ){
        width = width*10 + c - '0';
        c = *++fmt;
      }
    }
    if( width > etBUFSIZE-10 ){
      width = etBUFSIZE-10;
    }
    /* Get the precision */
    if( c=='.' ){
      precision = 0;
      c = *++fmt;
      if( c=='*' ){
        precision = va_arg(ap,int);
        if( precision<0 ) precision = -precision;
        c = *++fmt;
      }else{
        while( c>='0' && c<='9' ){
          precision = precision*10 + c - '0';
          c = *++fmt;
        }
      }
    }else{
      precision = -1;
    }
    /* Get the conversion type modifier */
    if( c=='l' ){
      flag_long = 1;
      c = *++fmt;
      if( c=='l' ){
        flag_longlong = 1;
        c = *++fmt;
      }else{
        flag_longlong = 0;
      }
    }else{
      flag_long = flag_longlong = 0;
    }
    /* Fetch the info entry for the field */
    infop = &fmtinfo[0];
    xtype = etINVALID;
    for(idx=0; idx<ArraySize(fmtinfo); idx++){
      if( c==fmtinfo[idx].fmttype ){
        infop = &fmtinfo[idx];
        if( useExtended || (infop->flags & FLAG_INTERN)==0 ){
          xtype = infop->type;
        }else{
          return;
        }
        break;
      }
    }
    zExtra = 0;


    /* Limit the precision to prevent overflowing buf[] during conversion */
    if( precision>etBUFSIZE-40 && (infop->flags & FLAG_STRING)==0 ){
      precision = etBUFSIZE-40;
    }

    /*
    ** At this point, variables are initialized as follows:
    **
    **   flag_alternateform          TRUE if a '#' is present.
    **   flag_altform2               TRUE if a '!' is present.
    **   flag_plussign               TRUE if a '+' is present.
    **   flag_leftjustify            TRUE if a '-' is present or if the
    **                               field width was negative.
    **   flag_zeropad                TRUE if the width began with 0.
    **   flag_long                   TRUE if the letter 'l' (ell) prefixed
    **                               the conversion character.
    **   flag_longlong               TRUE if the letter 'll' (ell ell) prefixed
    **                               the conversion character.
    **   flag_blanksign              TRUE if a ' ' is present.
    **   width                       The specified field width.  This is
    **                               always non-negative.  Zero is the default.
    **   precision                   The specified precision.  The default
    **                               is -1.
    **   xtype                       The class of the conversion.
    **   infop                       Pointer to the appropriate info struct.
    */
    switch( xtype ){
      case etPOINTER:
        flag_longlong = sizeof(char*)==sizeof(i64);
        flag_long = sizeof(char*)==sizeof(long int);
        /* Fall through into the next case */
      case etORDINAL:
      case etRADIX:
        if( infop->flags & FLAG_SIGNED ){
          i64 v;
          if( flag_longlong ){
            v = va_arg(ap,i64);
          }else if( flag_long ){
            v = va_arg(ap,long int);
          }else{
            v = va_arg(ap,int);
          }
          if( v<0 ){
            longvalue = -v;
            prefix = '-';
          }else{
            longvalue = v;
            if( flag_plussign )        prefix = '+';
            else if( flag_blanksign )  prefix = ' ';
            else                       prefix = 0;
          }
        }else{
          if( flag_longlong ){
            longvalue = va_arg(ap,u64);
          }else if( flag_long ){
            longvalue = va_arg(ap,unsigned long int);
          }else{
            longvalue = va_arg(ap,unsigned int);
          }
          prefix = 0;
        }
        if( longvalue==0 ) flag_alternateform = 0;
        if( flag_zeropad && precision<width-(prefix!=0) ){
          precision = width-(prefix!=0);
        }
        bufpt = &buf[etBUFSIZE-1];
        if( xtype==etORDINAL ){
          static const char zOrd[] = "thstndrd";
          int x = (int)(longvalue % 10);
          if( x>=4 || (longvalue/10)%10==1 ){
            x = 0;
          }
          buf[etBUFSIZE-3] = zOrd[x*2];
          buf[etBUFSIZE-2] = zOrd[x*2+1];
          bufpt -= 2;
        }
        {
          register const char *cset;      /* Use registers for speed */
          register int base;
          cset = &aDigits[infop->charset];
          base = infop->base;
          do{                                           /* Convert to ascii */
            *(--bufpt) = cset[longvalue%base];
            longvalue = longvalue/base;
          }while( longvalue>0 );
        }
        length = (int)(&buf[etBUFSIZE-1]-bufpt);
        for(idx=precision-length; idx>0; idx--){
          *(--bufpt) = '0';                             /* Zero pad */
        }
        if( prefix ) *(--bufpt) = prefix;               /* Add sign */
        if( flag_alternateform && infop->prefix ){      /* Add "0" or "0x" */
          const char *pre;
          char x;
          pre = &aPrefix[infop->prefix];
          for(; (x=(*pre))!=0; pre++) *(--bufpt) = x;
        }
        length = (int)(&buf[etBUFSIZE-1]-bufpt);
        break;
      case etFLOAT:
      case etEXP:
      case etGENERIC:
        realvalue = va_arg(ap,double);
#ifndef SQLITE_OMIT_FLOATING_POINT
        if( precision<0 ) precision = 6;         /* Set default precision */
        if( precision>etBUFSIZE/2-10 ) precision = etBUFSIZE/2-10;
        if( realvalue<0.0 ){
          realvalue = -realvalue;
          prefix = '-';
        }else{
          if( flag_plussign )          prefix = '+';
          else if( flag_blanksign )    prefix = ' ';
          else                         prefix = 0;
        }
        if( xtype==etGENERIC && precision>0 ) precision--;
#if 0
        /* Rounding works like BSD when the constant 0.4999 is used.  Wierd! */
        for(idx=precision, rounder=0.4999; idx>0; idx--, rounder*=0.1);
#else
        /* It makes more sense to use 0.5 */
        for(idx=precision, rounder=0.5; idx>0; idx--, rounder*=0.1){}
#endif
        if( xtype==etFLOAT ) realvalue += rounder;
        /* Normalize realvalue to within 10.0 > realvalue >= 1.0 */
        exp = 0;
        if( sqlite3IsNaN((double)realvalue) ){
          bufpt = "NaN";
          length = 3;
          break;
        }
        if( realvalue>0.0 ){
          while( realvalue>=1e32 && exp<=350 ){ realvalue *= 1e-32; exp+=32; }
          while( realvalue>=1e8 && exp<=350 ){ realvalue *= 1e-8; exp+=8; }
          while( realvalue>=10.0 && exp<=350 ){ realvalue *= 0.1; exp++; }
          while( realvalue<1e-8 ){ realvalue *= 1e8; exp-=8; }
          while( realvalue<1.0 ){ realvalue *= 10.0; exp--; }
          if( exp>350 ){
            if( prefix=='-' ){
              bufpt = "-Inf";
            }else if( prefix=='+' ){
              bufpt = "+Inf";
            }else{
              bufpt = "Inf";
            }
            length = sqlite3Strlen30(bufpt);
            break;
          }
        }
        bufpt = buf;
        /*
        ** If the field type is etGENERIC, then convert to either etEXP
        ** or etFLOAT, as appropriate.
        */
        flag_exp = xtype==etEXP;
        if( xtype!=etFLOAT ){
          realvalue += rounder;
          if( realvalue>=10.0 ){ realvalue *= 0.1; exp++; }
        }
        if( xtype==etGENERIC ){
          flag_rtz = !flag_alternateform;
          if( exp<-4 || exp>precision ){
            xtype = etEXP;
          }else{
            precision = precision - exp;
            xtype = etFLOAT;
          }
        }else{
          flag_rtz = 0;
        }
        if( xtype==etEXP ){
          e2 = 0;
        }else{
          e2 = exp;
        }
        nsd = 0;
        flag_dp = (precision>0 ?1:0) | flag_alternateform | flag_altform2;
        /* The sign in front of the number */
        if( prefix ){
          *(bufpt++) = prefix;
        }
        /* Digits prior to the decimal point */
        if( e2<0 ){
          *(bufpt++) = '0';
        }else{
          for(; e2>=0; e2--){
            *(bufpt++) = et_getdigit(&realvalue,&nsd);
          }
        }
        /* The decimal point */
        if( flag_dp ){
          *(bufpt++) = '.';
        }
        /* "0" digits after the decimal point but before the first
        ** significant digit of the number */
        for(e2++; e2<0; precision--, e2++){
          assert( precision>0 );
          *(bufpt++) = '0';
        }
        /* Significant digits after the decimal point */
        while( (precision--)>0 ){
          *(bufpt++) = et_getdigit(&realvalue,&nsd);
        }
        /* Remove trailing zeros and the "." if no digits follow the "." */
        if( flag_rtz && flag_dp ){
          while( bufpt[-1]=='0' ) *(--bufpt) = 0;
          assert( bufpt>buf );
          if( bufpt[-1]=='.' ){
            if( flag_altform2 ){
              *(bufpt++) = '0';
            }else{
              *(--bufpt) = 0;
            }
          }
        }
        /* Add the "eNNN" suffix */
        if( flag_exp || xtype==etEXP ){
          *(bufpt++) = aDigits[infop->charset];
          if( exp<0 ){
            *(bufpt++) = '-'; exp = -exp;
          }else{
            *(bufpt++) = '+';
          }
          if( exp>=100 ){
            *(bufpt++) = (char)((exp/100)+'0');        /* 100's digit */
            exp %= 100;
          }
          *(bufpt++) = (char)(exp/10+'0');             /* 10's digit */
          *(bufpt++) = (char)(exp%10+'0');             /* 1's digit */
        }
        *bufpt = 0;

        /* The converted number is in buf[] and zero terminated. Output it.
        ** Note that the number is in the usual order, not reversed as with
        ** integer conversions. */
        length = (int)(bufpt-buf);
        bufpt = buf;

        /* Special case:  Add leading zeros if the flag_zeropad flag is
        ** set and we are not left justified */
        if( flag_zeropad && !flag_leftjustify && length < width){
          int i;
          int nPad = width - length;
          for(i=width; i>=nPad; i--){
            bufpt[i] = bufpt[i-nPad];
          }
          i = prefix!=0;
          while( nPad-- ) bufpt[i++] = '0';
          length = width;
        }
#endif
        break;
      case etSIZE:
        *(va_arg(ap,int*)) = pAccum->nChar;
        length = width = 0;
        break;
      case etPERCENT:
        buf[0] = '%';
        bufpt = buf;
        length = 1;
        break;
      case etCHARX:
        c = va_arg(ap,int);
        buf[0] = (char)c;
        if( precision>=0 ){
          for(idx=1; idx<precision; idx++) buf[idx] = (char)c;
          length = precision;
        }else{
          length =1;
        }
        bufpt = buf;
        break;
      case etSTRING:
      case etDYNSTRING:
        bufpt = va_arg(ap,char*);
        if( bufpt==0 ){
          bufpt = "";
        }else if( xtype==etDYNSTRING ){
          zExtra = bufpt;
        }
        if( precision>=0 ){
          for(length=0; length<precision && bufpt[length]; length++){}
        }else{
          length = sqlite3Strlen30(bufpt);
        }
        break;
      case etSQLESCAPE:
      case etSQLESCAPE2:
      case etSQLESCAPE3: {
        int i, j, k, n, isnull;
        int needQuote;
        char ch;
        char q = ((xtype==etSQLESCAPE3)?'"':'\'');   /* Quote character */
        char *escarg = va_arg(ap,char*);
        isnull = escarg==0;
        if( isnull ) escarg = (xtype==etSQLESCAPE2 ? "NULL" : "(NULL)");
        k = precision;
        for(i=n=0; (ch=escarg[i])!=0 && k!=0; i++, k--){
          if( ch==q )  n++;
        }
        needQuote = !isnull && xtype==etSQLESCAPE2;
        n += i + 1 + needQuote*2;
        if( n>etBUFSIZE ){
          bufpt = zExtra = sqlite3Malloc( n );
          if( bufpt==0 ){
            pAccum->mallocFailed = 1;
            return;
          }
        }else{
          bufpt = buf;
        }
        j = 0;
        if( needQuote ) bufpt[j++] = q;
        k = i;
        for(i=0; i<k; i++){
          bufpt[j++] = ch = escarg[i];
          if( ch==q ) bufpt[j++] = ch;
        }
        if( needQuote ) bufpt[j++] = q;
        bufpt[j] = 0;
        length = j;
        /* The precision in %q and %Q means how many input characters to
        ** consume, not the length of the output...
        ** if( precision>=0 && precision<length ) length = precision; */
        break;
      }
      case etTOKEN: {
        Token *pToken = va_arg(ap, Token*);
        if( pToken ){
          sqlite3StrAccumAppend(pAccum, (const char*)pToken->z, pToken->n);
        }
        length = width = 0;
        break;
      }
      case etSRCLIST: {
        SrcList *pSrc = va_arg(ap, SrcList*);
        int k = va_arg(ap, int);
        struct SrcList_item *pItem = &pSrc->a[k];
        assert( k>=0 && k<pSrc->nSrc );
        if( pItem->zDatabase ){
          sqlite3StrAccumAppend(pAccum, pItem->zDatabase, -1);
          sqlite3StrAccumAppend(pAccum, ".", 1);
        }
        sqlite3StrAccumAppend(pAccum, pItem->zName, -1);
        length = width = 0;
        break;
      }
      default: {
        assert( xtype==etINVALID );
        return;
      }
    }/* End switch over the format type */
    /*
    ** The text of the conversion is pointed to by "bufpt" and is
    ** "length" characters long.  The field width is "width".  Do
    ** the output.
    */
    if( !flag_leftjustify ){
      register int nspace;
      nspace = width-length;
      if( nspace>0 ){
        appendSpace(pAccum, nspace);
      }
    }
    if( length>0 ){
      sqlite3StrAccumAppend(pAccum, bufpt, length);
    }
    if( flag_leftjustify ){
      register int nspace;
      nspace = width-length;
      if( nspace>0 ){
        appendSpace(pAccum, nspace);
      }
    }
    if( zExtra ){
      sqlite3_free(zExtra);
    }
  }/* End for loop over the format string */
} /* End of function */

/*
** Append N bytes of text from z to the StrAccum object.
*/
SQLITE_PRIVATE void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
  assert( z!=0 || N==0 );
  if( p->tooBig | p->mallocFailed ){
    testcase(p->tooBig);
    testcase(p->mallocFailed);
    return;
  }
  if( N<0 ){
    N = sqlite3Strlen30(z);
  }
  if( N==0 || NEVER(z==0) ){
    return;
  }
  if( p->nChar+N >= p->nAlloc ){
    char *zNew;
    if( !p->useMalloc ){
      p->tooBig = 1;
      N = p->nAlloc - p->nChar - 1;
      if( N<=0 ){
        return;
      }
    }else{
      i64 szNew = p->nChar;
      szNew += N + 1;
      if( szNew > p->mxAlloc ){
        sqlite3StrAccumReset(p);
        p->tooBig = 1;
        return;
      }else{
        p->nAlloc = (int)szNew;
      }
      zNew = sqlite3DbMallocRaw(p->db, p->nAlloc );
      if( zNew ){
        memcpy(zNew, p->zText, p->nChar);
        sqlite3StrAccumReset(p);
        p->zText = zNew;
      }else{
        p->mallocFailed = 1;
        sqlite3StrAccumReset(p);
        return;
      }
    }
  }
  memcpy(&p->zText[p->nChar], z, N);
  p->nChar += N;
}

/*
** Finish off a string by making sure it is zero-terminated.
** Return a pointer to the resulting string.  Return a NULL
** pointer if any kind of error was encountered.
*/
SQLITE_PRIVATE char *sqlite3StrAccumFinish(StrAccum *p){
  if( p->zText ){
    p->zText[p->nChar] = 0;
    if( p->useMalloc && p->zText==p->zBase ){
      p->zText = sqlite3DbMallocRaw(p->db, p->nChar+1 );
      if( p->zText ){
        memcpy(p->zText, p->zBase, p->nChar+1);
      }else{
        p->mallocFailed = 1;
      }
    }
  }
  return p->zText;
}

/*
** Reset an StrAccum string.  Reclaim all malloced memory.
*/
SQLITE_PRIVATE void sqlite3StrAccumReset(StrAccum *p){
  if( p->zText!=p->zBase ){
    sqlite3DbFree(p->db, p->zText);
  }
  p->zText = 0;
}

/*
** Initialize a string accumulator
*/
SQLITE_PRIVATE void sqlite3StrAccumInit(StrAccum *p, char *zBase, int n, int mx){
  p->zText = p->zBase = zBase;
  p->db = 0;
  p->nChar = 0;
  p->nAlloc = n;
  p->mxAlloc = mx;
  p->useMalloc = 1;
  p->tooBig = 0;
  p->mallocFailed = 0;
}

/*
** Print into memory obtained from sqliteMalloc().  Use the internal
** %-conversion extensions.
*/
SQLITE_PRIVATE char *sqlite3VMPrintf(sqlite3 *db, const char *zFormat, va_list ap){
  char *z;
  char zBase[SQLITE_PRINT_BUF_SIZE];
  StrAccum acc;
  assert( db!=0 );
  sqlite3StrAccumInit(&acc, zBase, sizeof(zBase),
                      db->aLimit[SQLITE_LIMIT_LENGTH]);
  acc.db = db;
  sqlite3VXPrintf(&acc, 1, zFormat, ap);
  z = sqlite3StrAccumFinish(&acc);
  if( acc.mallocFailed ){
    db->mallocFailed = 1;
  }
  return z;
}

/*
** Print into memory obtained from sqliteMalloc().  Use the internal
** %-conversion extensions.
*/
SQLITE_PRIVATE char *sqlite3MPrintf(sqlite3 *db, const char *zFormat, ...){
  va_list ap;
  char *z;
  va_start(ap, zFormat);
  z = sqlite3VMPrintf(db, zFormat, ap);
  va_end(ap);
  return z;
}

/*
** Like sqlite3MPrintf(), but call sqlite3DbFree() on zStr after formatting
** the string and before returnning.  This routine is intended to be used
** to modify an existing string.  For example:
**
**       x = sqlite3MPrintf(db, x, "prefix %s suffix", x);
**
*/
SQLITE_PRIVATE char *sqlite3MAppendf(sqlite3 *db, char *zStr, const char *zFormat, ...){
  va_list ap;
  char *z;
  va_start(ap, zFormat);
  z = sqlite3VMPrintf(db, zFormat, ap);
  va_end(ap);
  sqlite3DbFree(db, zStr);
  return z;
}

/*
** Print into memory obtained from sqlite3_malloc().  Omit the internal
** %-conversion extensions.
*/
SQLITE_API char *sqlite3_vmprintf(const char *zFormat, va_list ap){
  char *z;
  char zBase[SQLITE_PRINT_BUF_SIZE];
  StrAccum acc;
#ifndef SQLITE_OMIT_AUTOINIT
  if( sqlite3_initialize() ) return 0;
#endif
  sqlite3StrAccumInit(&acc, zBase, sizeof(zBase), SQLITE_MAX_LENGTH);
  sqlite3VXPrintf(&acc, 0, zFormat, ap);
  z = sqlite3StrAccumFinish(&acc);
  return z;
}

/*
** Print into memory obtained from sqlite3_malloc()().  Omit the internal
** %-conversion extensions.
*/
SQLITE_API char *sqlite3_mprintf(const char *zFormat, ...){
  va_list ap;
  char *z;
#ifndef SQLITE_OMIT_AUTOINIT
  if( sqlite3_initialize() ) return 0;
#endif
  va_start(ap, zFormat);
  z = sqlite3_vmprintf(zFormat, ap);
  va_end(ap);
  return z;
}

/*
** sqlite3_snprintf() works like snprintf() except that it ignores the
** current locale settings.  This is important for SQLite because we
** are not able to use a "," as the decimal point in place of "." as
** specified by some locales.
*/
SQLITE_API char *sqlite3_snprintf(int n, char *zBuf, const char *zFormat, ...){
  char *z;
  va_list ap;
  StrAccum acc;

  if( n<=0 ){
    return zBuf;
  }
  sqlite3StrAccumInit(&acc, zBuf, n, 0);
  acc.useMalloc = 0;
  va_start(ap,zFormat);
  sqlite3VXPrintf(&acc, 0, zFormat, ap);
  va_end(ap);
  z = sqlite3StrAccumFinish(&acc);
  return z;
}

/*
** This is the routine that actually formats the sqlite3_log() message.
** We house it in a separate routine from sqlite3_log() to avoid using
** stack space on small-stack systems when logging is disabled.
**
** sqlite3_log() must render into a static buffer.  It cannot dynamically
** allocate memory because it might be called while the memory allocator
** mutex is held.
*/
static void renderLogMsg(int iErrCode, const char *zFormat, va_list ap){
  StrAccum acc;                           /* String accumulator */
#ifdef SQLITE_SMALL_STACK
  char zMsg[150];                         /* Complete log message */
#else
  char zMsg[400];                         /* Complete log message */
#endif

  sqlite3StrAccumInit(&acc, zMsg, sizeof(zMsg), 0);
  acc.useMalloc = 0;
  sqlite3VXPrintf(&acc, 0, zFormat, ap);
  sqlite3GlobalConfig.xLog(sqlite3GlobalConfig.pLogArg, iErrCode,
                           sqlite3StrAccumFinish(&acc));
}

/*
** Format and write a message to the log if logging is enabled.
*/
SQLITE_API void sqlite3_log(int iErrCode, const char *zFormat, ...){
  va_list ap;                             /* Vararg list */
  if( sqlite3GlobalConfig.xLog ){
    va_start(ap, zFormat);
    renderLogMsg(iErrCode, zFormat, ap);
    va_end(ap);
  }
}

#if defined(SQLITE_DEBUG)
/*
** A version of printf() that understands %lld.  Used for debugging.
** The printf() built into some versions of windows does not understand %lld
** and segfaults if you give it a long long int.
*/
SQLITE_PRIVATE void sqlite3DebugPrintf(const char *zFormat, ...){
  va_list ap;
  StrAccum acc;
  char zBuf[500];
  sqlite3StrAccumInit(&acc, zBuf, sizeof(zBuf), 0);
  acc.useMalloc = 0;
  va_start(ap,zFormat);
  sqlite3VXPrintf(&acc, 0, zFormat, ap);
  va_end(ap);
  sqlite3StrAccumFinish(&acc);
  fprintf(stdout,"%s", zBuf);
  fflush(stdout);
}
#endif

#ifndef SQLITE_OMIT_TRACE
/*
** variable-argument wrapper around sqlite3VXPrintf().
*/
SQLITE_PRIVATE void sqlite3XPrintf(StrAccum *p, const char *zFormat, ...){
  va_list ap;
  va_start(ap,zFormat);
  sqlite3VXPrintf(p, 1, zFormat, ap);
  va_end(ap);
}
#endif

/************** End of printf.c **********************************************/
/************** Begin file random.c ******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code to implement a pseudo-random number
** generator (PRNG) for SQLite.
**
** Random numbers are used by some of the database backends in order
** to generate random integer keys for tables or random filenames.
*/


/* All threads share a single random number generator.
** This structure is the current state of the generator.
*/
static SQLITE_WSD struct sqlite3PrngType {
  unsigned char isInit;          /* True if initialized */
  unsigned char i, j;            /* State variables */
  unsigned char s[256];          /* State variables */
} sqlite3Prng;

/*
** Get a single 8-bit random value from the RC4 PRNG.  The Mutex
** must be held while executing this routine.
**
** Why not just use a library random generator like lrand48() for this?
** Because the OP_NewRowid opcode in the VDBE depends on having a very
** good source of random numbers.  The lrand48() library function may
** well be good enough.  But maybe not.  Or maybe lrand48() has some
** subtle problems on some systems that could cause problems.  It is hard
** to know.  To minimize the risk of problems due to bad lrand48()
** implementations, SQLite uses this random number generator based
** on RC4, which we know works very well.
**
** (Later):  Actually, OP_NewRowid does not depend on a good source of
** randomness any more.  But we will leave this code in all the same.
*/
static u8 randomByte(void){
  unsigned char t;


  /* The "wsdPrng" macro will resolve to the pseudo-random number generator
  ** state vector.  If writable static data is unsupported on the target,
  ** we have to locate the state vector at run-time.  In the more common
  ** case where writable static data is supported, wsdPrng can refer directly
  ** to the "sqlite3Prng" state vector declared above.
  */
#ifdef SQLITE_OMIT_WSD
  struct sqlite3PrngType *p = &GLOBAL(struct sqlite3PrngType, sqlite3Prng);
# define wsdPrng p[0]
#else
# define wsdPrng sqlite3Prng
#endif


  /* Initialize the state of the random number generator once,
  ** the first time this routine is called.  The seed value does
  ** not need to contain a lot of randomness since we are not
  ** trying to do secure encryption or anything like that...
  **
  ** Nothing in this file or anywhere else in SQLite does any kind of
  ** encryption.  The RC4 algorithm is being used as a PRNG (pseudo-random
  ** number generator) not as an encryption device.
  */
  if( !wsdPrng.isInit ){
    int i;
    char k[256];
    wsdPrng.j = 0;
    wsdPrng.i = 0;
    sqlite3OsRandomness(sqlite3_vfs_find(0), 256, k);
    for(i=0; i<256; i++){
      wsdPrng.s[i] = (u8)i;
    }
    for(i=0; i<256; i++){
      wsdPrng.j += wsdPrng.s[i] + k[i];
      t = wsdPrng.s[wsdPrng.j];
      wsdPrng.s[wsdPrng.j] = wsdPrng.s[i];
      wsdPrng.s[i] = t;
    }
    wsdPrng.isInit = 1;
  }

  /* Generate and return single random byte
  */
  wsdPrng.i++;
  t = wsdPrng.s[wsdPrng.i];
  wsdPrng.j += t;
  wsdPrng.s[wsdPrng.i] = wsdPrng.s[wsdPrng.j];
  wsdPrng.s[wsdPrng.j] = t;
  t += wsdPrng.s[wsdPrng.i];
  return wsdPrng.s[t];
}

/*
** Return N random bytes.
*/
SQLITE_API void sqlite3_randomness(int N, void *pBuf){
  unsigned char *zBuf = pBuf;
#if SQLITE_THREADSAFE
  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_PRNG);
#endif
  sqlite3_mutex_enter(mutex);
  while( N-- ){
    *(zBuf++) = randomByte();
  }
  sqlite3_mutex_leave(mutex);
}

#ifndef SQLITE_OMIT_BUILTIN_TEST
/*
** For testing purposes, we sometimes want to preserve the state of
** PRNG and restore the PRNG to its saved state at a later time, or
** to reset the PRNG to its initial state.  These routines accomplish
** those tasks.
**
** The sqlite3_test_control() interface calls these routines to
** control the PRNG.
*/
static SQLITE_WSD struct sqlite3PrngType sqlite3SavedPrng;
SQLITE_PRIVATE void sqlite3PrngSaveState(void){
  memcpy(
    &GLOBAL(struct sqlite3PrngType, sqlite3SavedPrng),
    &GLOBAL(struct sqlite3PrngType, sqlite3Prng),
    sizeof(sqlite3Prng)
  );
}
SQLITE_PRIVATE void sqlite3PrngRestoreState(void){
  memcpy(
    &GLOBAL(struct sqlite3PrngType, sqlite3Prng),
    &GLOBAL(struct sqlite3PrngType, sqlite3SavedPrng),
    sizeof(sqlite3Prng)
  );
}
SQLITE_PRIVATE void sqlite3PrngResetState(void){
  GLOBAL(struct sqlite3PrngType, sqlite3Prng).isInit = 0;
}
#endif /* SQLITE_OMIT_BUILTIN_TEST */

/************** End of random.c **********************************************/
/************** Begin file utf.c *********************************************/
/*
** 2004 April 13
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used to translate between UTF-8,
** UTF-16, UTF-16BE, and UTF-16LE.
**
** Notes on UTF-8:
**
**   Byte-0    Byte-1    Byte-2    Byte-3    Value
**  0xxxxxxx                                 00000000 00000000 0xxxxxxx
**  110yyyyy  10xxxxxx                       00000000 00000yyy yyxxxxxx
**  1110zzzz  10yyyyyy  10xxxxxx             00000000 zzzzyyyy yyxxxxxx
**  11110uuu  10uuzzzz  10yyyyyy  10xxxxxx   000uuuuu zzzzyyyy yyxxxxxx
**
**
** Notes on UTF-16:  (with wwww+1==uuuuu)
**
**      Word-0               Word-1          Value
**  110110ww wwzzzzyy   110111yy yyxxxxxx    000uuuuu zzzzyyyy yyxxxxxx
**  zzzzyyyy yyxxxxxx                        00000000 zzzzyyyy yyxxxxxx
**
**
** BOM or Byte Order Mark:
**     0xff 0xfe   little-endian utf-16 follows
**     0xfe 0xff   big-endian utf-16 follows
**
*/
/************** Include vdbeInt.h in the middle of utf.c *********************/
/************** Begin file vdbeInt.h *****************************************/
/*
** 2003 September 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the header file for information that is private to the
** VDBE.  This information used to all be at the top of the single
** source code file "vdbe.c".  When that file became too big (over
** 6000 lines long) it was split up into several smaller files and
** this header information was factored out.
*/
#ifndef _VDBEINT_H_
#define _VDBEINT_H_

/*
** SQL is translated into a sequence of instructions to be
** executed by a virtual machine.  Each instruction is an instance
** of the following structure.
*/
typedef struct VdbeOp Op;

/*
** Boolean values
*/
typedef unsigned char Bool;

/*
** A cursor is a pointer into a single BTree within a database file.
** The cursor can seek to a BTree entry with a particular key, or
** loop over all entries of the Btree.  You can also insert new BTree
** entries or retrieve the key or data from the entry that the cursor
** is currently pointing to.
**
** Every cursor that the virtual machine has open is represented by an
** instance of the following structure.
**
** If the VdbeCursor.isTriggerRow flag is set it means that this cursor is
** really a single row that represents the NEW or OLD pseudo-table of
** a row trigger.  The data for the row is stored in VdbeCursor.pData and
** the rowid is in VdbeCursor.iKey.
*/
struct VdbeCursor {
  BtCursor *pCursor;    /* The cursor structure of the backend */
  int iDb;              /* Index of cursor database in db->aDb[] (or -1) */
  i64 lastRowid;        /* Last rowid from a Next or NextIdx operation */
  Bool zeroed;          /* True if zeroed out and ready for reuse */
  Bool rowidIsValid;    /* True if lastRowid is valid */
  Bool atFirst;         /* True if pointing to first entry */
  Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
  Bool nullRow;         /* True if pointing to a row with no data */
  Bool deferredMoveto;  /* A call to sqlite3BtreeMoveto() is needed */
  Bool isTable;         /* True if a table requiring integer keys */
  Bool isIndex;         /* True if an index containing keys only - no data */
  i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
  Btree *pBt;           /* Separate file holding temporary table */
  int pseudoTableReg;   /* Register holding pseudotable content. */
  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  int nField;           /* Number of fields in the header */
  i64 seqCount;         /* Sequence counter */
  sqlite3_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
  const sqlite3_module *pModule;     /* Module for cursor pVtabCursor */

  /* Result of last sqlite3BtreeMoveto() done by an OP_NotExists or
  ** OP_IsUnique opcode on this cursor. */
  int seekResult;

  /* Cached information about the header for the data record that the
  ** cursor is currently pointing to.  Only valid if cacheStatus matches
  ** Vdbe.cacheCtr.  Vdbe.cacheCtr will never take on the value of
  ** CACHE_STALE and so setting cacheStatus=CACHE_STALE guarantees that
  ** the cache is out of date.
  **
  ** aRow might point to (ephemeral) data for the current row, or it might
  ** be NULL.
  */
  u32 cacheStatus;      /* Cache is valid if this matches Vdbe.cacheCtr */
  int payloadSize;      /* Total number of bytes in the record */
  u32 *aType;           /* Type values for all entries in the record */
  u32 *aOffset;         /* Cached offsets to the start of each columns data */
  u8 *aRow;             /* Data for the current row, if all on one page */
};
typedef struct VdbeCursor VdbeCursor;

/*
** When a sub-program is executed (OP_Program), a structure of this type
** is allocated to store the current value of the program counter, as
** well as the current memory cell array and various other frame specific
** values stored in the Vdbe struct. When the sub-program is finished,
** these values are copied back to the Vdbe from the VdbeFrame structure,
** restoring the state of the VM to as it was before the sub-program
** began executing.
**
** Frames are stored in a linked list headed at Vdbe.pParent. Vdbe.pParent
** is the parent of the current frame, or zero if the current frame
** is the main Vdbe program.
*/
typedef struct VdbeFrame VdbeFrame;
struct VdbeFrame {
  Vdbe *v;                /* VM this frame belongs to */
  int pc;                 /* Program Counter */
  Op *aOp;                /* Program instructions */
  int nOp;                /* Size of aOp array */
  Mem *aMem;              /* Array of memory cells */
  int nMem;               /* Number of entries in aMem */
  VdbeCursor **apCsr;     /* Element of Vdbe cursors */
  u16 nCursor;            /* Number of entries in apCsr */
  void *token;            /* Copy of SubProgram.token */
  int nChildMem;          /* Number of memory cells for child frame */
  int nChildCsr;          /* Number of cursors for child frame */
  i64 lastRowid;          /* Last insert rowid (sqlite3.lastRowid) */
  int nChange;            /* Statement changes (Vdbe.nChanges)     */
  VdbeFrame *pParent;     /* Parent of this frame */
};

#define VdbeFrameMem(p) ((Mem *)&((u8 *)p)[ROUND8(sizeof(VdbeFrame))])

/*
** A value for VdbeCursor.cacheValid that means the cache is always invalid.
*/
#define CACHE_STALE 0

/*
** Internally, the vdbe manipulates nearly all SQL values as Mem
** structures. Each Mem struct may cache multiple representations (string,
** integer etc.) of the same value.  A value (and therefore Mem structure)
** has the following properties:
**
** Each value has a manifest type. The manifest type of the value stored
** in a Mem struct is returned by the MemType(Mem*) macro. The type is
** one of SQLITE_NULL, SQLITE_INTEGER, SQLITE_REAL, SQLITE_TEXT or
** SQLITE_BLOB.
*/
struct Mem {
  union {
    i64 i;              /* Integer value. */
    int nZero;          /* Used when bit MEM_Zero is set in flags */
    FuncDef *pDef;      /* Used only when flags==MEM_Agg */
    RowSet *pRowSet;    /* Used only when flags==MEM_RowSet */
    VdbeFrame *pFrame;  /* Used when flags==MEM_Frame */
  } u;
  double r;           /* Real value */
  sqlite3 *db;        /* The associated database connection */
  char *z;            /* String or BLOB value */
  int n;              /* Number of characters in string value, excluding '\0' */
  u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
  u8  type;           /* One of SQLITE_NULL, SQLITE_TEXT, SQLITE_INTEGER, etc */
  u8  enc;            /* SQLITE_UTF8, SQLITE_UTF16BE, SQLITE_UTF16LE */
  void (*xDel)(void *);  /* If not null, call this function to delete Mem.z */
  char *zMalloc;      /* Dynamic buffer allocated by sqlite3_malloc() */
};

/* One or more of the following flags are set to indicate the validOK
** representations of the value stored in the Mem struct.
**
** If the MEM_Null flag is set, then the value is an SQL NULL value.
** No other flags may be set in this case.
**
** If the MEM_Str flag is set then Mem.z points at a string representation.
** Usually this is encoded in the same unicode encoding as the main
** database (see below for exceptions). If the MEM_Term flag is also
** set, then the string is nul terminated. The MEM_Int and MEM_Real
** flags may coexist with the MEM_Str flag.
**
** Multiple of these values can appear in Mem.flags.  But only one
** at a time can appear in Mem.type.
*/
#define MEM_Null      0x0001   /* Value is NULL */
#define MEM_Str       0x0002   /* Value is a string */
#define MEM_Int       0x0004   /* Value is an integer */
#define MEM_Real      0x0008   /* Value is a real number */
#define MEM_Blob      0x0010   /* Value is a BLOB */
#define MEM_RowSet    0x0020   /* Value is a RowSet object */
#define MEM_Frame     0x0040   /* Value is a VdbeFrame object */
#define MEM_TypeMask  0x00ff   /* Mask of type bits */

/* Whenever Mem contains a valid string or blob representation, one of
** the following flags must be set to determine the memory management
** policy for Mem.z.  The MEM_Term flag tells us whether or not the
** string is \000 or \u0000 terminated
*/
#define MEM_Term      0x0200   /* String rep is nul terminated */
#define MEM_Dyn       0x0400   /* Need to call sqliteFree() on Mem.z */
#define MEM_Static    0x0800   /* Mem.z points to a static string */
#define MEM_Ephem     0x1000   /* Mem.z points to an ephemeral string */
#define MEM_Agg       0x2000   /* Mem.z points to an agg function context */
#define MEM_Zero      0x4000   /* Mem.i contains count of 0s appended to blob */

#ifdef SQLITE_OMIT_INCRBLOB
  #undef MEM_Zero
  #define MEM_Zero 0x0000
#endif


/*
** Clear any existing type flags from a Mem and replace them with f
*/
#define MemSetTypeFlag(p, f) \
   ((p)->flags = ((p)->flags&~(MEM_TypeMask|MEM_Zero))|f)


/* A VdbeFunc is just a FuncDef (defined in sqliteInt.h) that contains
** additional information about auxiliary information bound to arguments
** of the function.  This is used to implement the sqlite3_get_auxdata()
** and sqlite3_set_auxdata() APIs.  The "auxdata" is some auxiliary data
** that can be associated with a constant argument to a function.  This
** allows functions such as "regexp" to compile their constant regular
** expression argument once and reused the compiled code for multiple
** invocations.
*/
struct VdbeFunc {
  FuncDef *pFunc;               /* The definition of the function */
  int nAux;                     /* Number of entries allocated for apAux[] */
  struct AuxData {
    void *pAux;                   /* Aux data for the i-th argument */
    void (*xDelete)(void *);      /* Destructor for the aux data */
  } apAux[1];                   /* One slot for each function argument */
};

/*
** The "context" argument for a installable function.  A pointer to an
** instance of this structure is the first argument to the routines used
** implement the SQL functions.
**
** There is a typedef for this structure in sqlite.h.  So all routines,
** even the public interface to SQLite, can use a pointer to this structure.
** But this file is the only place where the internal details of this
** structure are known.
**
** This structure is defined inside of vdbeInt.h because it uses substructures
** (Mem) which are only defined there.
*/
struct sqlite3_context {
  FuncDef *pFunc;       /* Pointer to function information.  MUST BE FIRST */
  VdbeFunc *pVdbeFunc;  /* Auxilary data, if created. */
  Mem s;                /* The return value is stored here */
  Mem *pMem;            /* Memory cell used to store aggregate context */
  int isError;          /* Error code returned by the function. */
  CollSeq *pColl;       /* Collating sequence */
};

/*
** A Set structure is used for quick testing to see if a value
** is part of a small set.  Sets are used to implement code like
** this:
**            x.y IN ('hi','hoo','hum')
*/
typedef struct Set Set;
struct Set {
  Hash hash;             /* A set is just a hash table */
  HashElem *prev;        /* Previously accessed hash elemen */
};

/*
** An instance of the virtual machine.  This structure contains the complete
** state of the virtual machine.
**
** The "sqlite3_stmt" structure pointer that is returned by sqlite3_compile()
** is really a pointer to an instance of this structure.
**
** The Vdbe.inVtabMethod variable is set to non-zero for the duration of
** any virtual table method invocations made by the vdbe program. It is
** set to 2 for xDestroy method calls and 1 for all other methods. This
** variable is used for two purposes: to allow xDestroy methods to execute
** "DROP TABLE" statements and to prevent some nasty side effects of
** malloc failure when SQLite is invoked recursively by a virtual table
** method function.
*/
struct Vdbe {
  sqlite3 *db;            /* The database connection that owns this statement */
  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
  int nOp;                /* Number of instructions in the program */
  int nOpAlloc;           /* Number of slots allocated for aOp[] */
  Op *aOp;                /* Space to hold the virtual machine's program */
  int nLabel;             /* Number of labels used */
  int nLabelAlloc;        /* Number of slots allocated in aLabel[] */
  int *aLabel;            /* Space to hold the labels */
  Mem **apArg;            /* Arguments to currently executing user function */
  Mem *aColName;          /* Column names to return */
  Mem *pResultSet;        /* Pointer to an array of results */
  u16 nResColumn;         /* Number of columns in one row of the result set */
  u16 nCursor;            /* Number of slots in apCsr[] */
  VdbeCursor **apCsr;     /* One element of this array for each open cursor */
  u8 errorAction;         /* Recovery action to do in case of an error */
  u8 okVar;               /* True if azVar[] has been initialized */
  ynVar nVar;             /* Number of entries in aVar[] */
  Mem *aVar;              /* Values for the OP_Variable opcode. */
  char **azVar;           /* Name of variables */
  u32 magic;              /* Magic number for sanity checking */
  int nMem;               /* Number of memory locations currently allocated */
  Mem *aMem;              /* The memory locations */
  u32 cacheCtr;           /* VdbeCursor row cache generation counter */
  int pc;                 /* The program counter */
  int rc;                 /* Value to return */
  char *zErrMsg;          /* Error message written here */
  u8 explain;             /* True if EXPLAIN present on SQL command */
  u8 changeCntOn;         /* True to update the change-counter */
  u8 expired;             /* True if the VM needs to be recompiled */
  u8 runOnlyOnce;         /* Automatically expire on reset */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 inVtabMethod;        /* See comments above */
  u8 usesStmtJournal;     /* True if uses a statement journal */
  u8 readOnly;            /* True for read-only statements */
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  int btreeMask;          /* Bitmask of db->aDb[] entries referenced */
  i64 startTime;          /* Time when query started - used for profiling */
  BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */
  int aCounter[2];        /* Counters used by sqlite3_stmt_status() */
  char *zSql;             /* Text of the SQL statement that generated this */
  void *pFree;            /* Free this when deleting the vdbe */
  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */
  int iStatement;         /* Statement number (or 0 if has not opened stmt) */
#ifdef SQLITE_DEBUG
  FILE *trace;            /* Write an execution trace here, if not NULL */
#endif
  VdbeFrame *pFrame;      /* Parent frame */
  int nFrame;             /* Number of frames in pFrame list */
  u32 expmask;            /* Binding to these vars invalidates VM */
};

/*
** The following are allowed values for Vdbe.magic
*/
#define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */
#define VDBE_MAGIC_RUN      0xbdf20da3    /* VDBE is ready to execute */
#define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */
#define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */

/*
** Function prototypes
*/
SQLITE_PRIVATE void sqlite3VdbeFreeCursor(Vdbe *, VdbeCursor*);
void sqliteVdbePopStack(Vdbe*,int);
SQLITE_PRIVATE int sqlite3VdbeCursorMoveto(VdbeCursor*);
#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
SQLITE_PRIVATE void sqlite3VdbePrintOp(FILE*, int, Op*);
#endif
SQLITE_PRIVATE u32 sqlite3VdbeSerialTypeLen(u32);
SQLITE_PRIVATE u32 sqlite3VdbeSerialType(Mem*, int);
SQLITE_PRIVATE u32 sqlite3VdbeSerialPut(unsigned char*, int, Mem*, int);
SQLITE_PRIVATE u32 sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);
SQLITE_PRIVATE void sqlite3VdbeDeleteAuxData(VdbeFunc*, int);

int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
SQLITE_PRIVATE int sqlite3VdbeIdxKeyCompare(VdbeCursor*,UnpackedRecord*,int*);
SQLITE_PRIVATE int sqlite3VdbeIdxRowid(sqlite3*, BtCursor *, i64 *);
SQLITE_PRIVATE int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
SQLITE_PRIVATE int sqlite3VdbeExec(Vdbe*);
SQLITE_PRIVATE int sqlite3VdbeList(Vdbe*);
SQLITE_PRIVATE int sqlite3VdbeHalt(Vdbe*);
SQLITE_PRIVATE int sqlite3VdbeChangeEncoding(Mem *, int);
SQLITE_PRIVATE int sqlite3VdbeMemTooBig(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemCopy(Mem*, const Mem*);
SQLITE_PRIVATE void sqlite3VdbeMemShallowCopy(Mem*, const Mem*, int);
SQLITE_PRIVATE void sqlite3VdbeMemMove(Mem*, Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemNulTerminate(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemSetStr(Mem*, const char*, int, u8, void(*)(void*));
SQLITE_PRIVATE void sqlite3VdbeMemSetInt64(Mem*, i64);
SQLITE_PRIVATE void sqlite3VdbeMemSetDouble(Mem*, double);
SQLITE_PRIVATE void sqlite3VdbeMemSetNull(Mem*);
SQLITE_PRIVATE void sqlite3VdbeMemSetZeroBlob(Mem*,int);
SQLITE_PRIVATE void sqlite3VdbeMemSetRowSet(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemMakeWriteable(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemStringify(Mem*, int);
SQLITE_PRIVATE i64 sqlite3VdbeIntValue(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemIntegerify(Mem*);
SQLITE_PRIVATE double sqlite3VdbeRealValue(Mem*);
SQLITE_PRIVATE void sqlite3VdbeIntegerAffinity(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemRealify(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemNumerify(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemFromBtree(BtCursor*,int,int,int,Mem*);
SQLITE_PRIVATE void sqlite3VdbeMemRelease(Mem *p);
SQLITE_PRIVATE void sqlite3VdbeMemReleaseExternal(Mem *p);
SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
SQLITE_PRIVATE const char *sqlite3OpcodeName(int);
SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *, int);
SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame*);
SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *);
SQLITE_PRIVATE void sqlite3VdbeMemStoreType(Mem *pMem);

#ifndef SQLITE_OMIT_FOREIGN_KEY
SQLITE_PRIVATE int sqlite3VdbeCheckFk(Vdbe *, int);
#else
# define sqlite3VdbeCheckFk(p,i) 0
#endif

#ifndef SQLITE_OMIT_SHARED_CACHE
SQLITE_PRIVATE void sqlite3VdbeMutexArrayEnter(Vdbe *p);
#else
# define sqlite3VdbeMutexArrayEnter(p)
#endif

SQLITE_PRIVATE int sqlite3VdbeMemTranslate(Mem*, u8);
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   void sqlite3VdbePrintSql(Vdbe*);
SQLITE_PRIVATE   void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf);
#endif
SQLITE_PRIVATE int sqlite3VdbeMemHandleBom(Mem *pMem);

#ifndef SQLITE_OMIT_INCRBLOB
SQLITE_PRIVATE   int sqlite3VdbeMemExpandBlob(Mem *);
#else
  #define sqlite3VdbeMemExpandBlob(x) SQLITE_OK
#endif

#endif /* !defined(_VDBEINT_H_) */

/************** End of vdbeInt.h *********************************************/
/************** Continuing where we left off in utf.c ************************/

#ifndef SQLITE_AMALGAMATION
/*
** The following constant value is used by the SQLITE_BIGENDIAN and
** SQLITE_LITTLEENDIAN macros.
*/
SQLITE_PRIVATE const int sqlite3one = 1;
#endif /* SQLITE_AMALGAMATION */

/*
** This lookup table is used to help decode the first byte of
** a multi-byte UTF8 character.
*/
static const unsigned char sqlite3Utf8Trans1[] = {
  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
  0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
  0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
  0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x00, 0x00,
};


#define WRITE_UTF8(zOut, c) {                          \
  if( c<0x00080 ){                                     \
    *zOut++ = (u8)(c&0xFF);                            \
  }                                                    \
  else if( c<0x00800 ){                                \
    *zOut++ = 0xC0 + (u8)((c>>6)&0x1F);                \
    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
  }                                                    \
  else if( c<0x10000 ){                                \
    *zOut++ = 0xE0 + (u8)((c>>12)&0x0F);               \
    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
  }else{                                               \
    *zOut++ = 0xF0 + (u8)((c>>18) & 0x07);             \
    *zOut++ = 0x80 + (u8)((c>>12) & 0x3F);             \
    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
  }                                                    \
}

#define WRITE_UTF16LE(zOut, c) {                                    \
  if( c<=0xFFFF ){                                                  \
    *zOut++ = (u8)(c&0x00FF);                                       \
    *zOut++ = (u8)((c>>8)&0x00FF);                                  \
  }else{                                                            \
    *zOut++ = (u8)(((c>>10)&0x003F) + (((c-0x10000)>>10)&0x00C0));  \
    *zOut++ = (u8)(0x00D8 + (((c-0x10000)>>18)&0x03));              \
    *zOut++ = (u8)(c&0x00FF);                                       \
    *zOut++ = (u8)(0x00DC + ((c>>8)&0x03));                         \
  }                                                                 \
}

#define WRITE_UTF16BE(zOut, c) {                                    \
  if( c<=0xFFFF ){                                                  \
    *zOut++ = (u8)((c>>8)&0x00FF);                                  \
    *zOut++ = (u8)(c&0x00FF);                                       \
  }else{                                                            \
    *zOut++ = (u8)(0x00D8 + (((c-0x10000)>>18)&0x03));              \
    *zOut++ = (u8)(((c>>10)&0x003F) + (((c-0x10000)>>10)&0x00C0));  \
    *zOut++ = (u8)(0x00DC + ((c>>8)&0x03));                         \
    *zOut++ = (u8)(c&0x00FF);                                       \
  }                                                                 \
}

#define READ_UTF16LE(zIn, TERM, c){                                   \
  c = (*zIn++);                                                       \
  c += ((*zIn++)<<8);                                                 \
  if( c>=0xD800 && c<0xE000 && TERM ){                                \
    int c2 = (*zIn++);                                                \
    c2 += ((*zIn++)<<8);                                              \
    c = (c2&0x03FF) + ((c&0x003F)<<10) + (((c&0x03C0)+0x0040)<<10);   \
  }                                                                   \
}

#define READ_UTF16BE(zIn, TERM, c){                                   \
  c = ((*zIn++)<<8);                                                  \
  c += (*zIn++);                                                      \
  if( c>=0xD800 && c<0xE000 && TERM ){                                \
    int c2 = ((*zIn++)<<8);                                           \
    c2 += (*zIn++);                                                   \
    c = (c2&0x03FF) + ((c&0x003F)<<10) + (((c&0x03C0)+0x0040)<<10);   \
  }                                                                   \
}

/*
** Translate a single UTF-8 character.  Return the unicode value.
**
** During translation, assume that the byte that zTerm points
** is a 0x00.
**
** Write a pointer to the next unread byte back into *pzNext.
**
** Notes On Invalid UTF-8:
**
**  *  This routine never allows a 7-bit character (0x00 through 0x7f) to
**     be encoded as a multi-byte character.  Any multi-byte character that
**     attempts to encode a value between 0x00 and 0x7f is rendered as 0xfffd.
**
**  *  This routine never allows a UTF16 surrogate value to be encoded.
**     If a multi-byte character attempts to encode a value between
**     0xd800 and 0xe000 then it is rendered as 0xfffd.
**
**  *  Bytes in the range of 0x80 through 0xbf which occur as the first
**     byte of a character are interpreted as single-byte characters
**     and rendered as themselves even though they are technically
**     invalid characters.
**
**  *  This routine accepts an infinite number of different UTF8 encodings
**     for unicode values 0x80 and greater.  It do not change over-length
**     encodings to 0xfffd as some systems recommend.
*/
#define READ_UTF8(zIn, zTerm, c)                           \
  c = *(zIn++);                                            \
  if( c>=0xc0 ){                                           \
    c = sqlite3Utf8Trans1[c-0xc0];                         \
    while( zIn!=zTerm && (*zIn & 0xc0)==0x80 ){            \
      c = (c<<6) + (0x3f & *(zIn++));                      \
    }                                                      \
    if( c<0x80                                             \
        || (c&0xFFFFF800)==0xD800                          \
        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
  }
SQLITE_PRIVATE int sqlite3Utf8Read(
  const unsigned char *zIn,       /* First byte of UTF-8 character */
  const unsigned char **pzNext    /* Write first byte past UTF-8 char here */
){
  int c;

  /* Same as READ_UTF8() above but without the zTerm parameter.
  ** For this routine, we assume the UTF8 string is always zero-terminated.
  */
  c = *(zIn++);
  if( c>=0xc0 ){
    c = sqlite3Utf8Trans1[c-0xc0];
    while( (*zIn & 0xc0)==0x80 ){
      c = (c<<6) + (0x3f & *(zIn++));
    }
    if( c<0x80
        || (c&0xFFFFF800)==0xD800
        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }
  }
  *pzNext = zIn;
  return c;
}




/*
** If the TRANSLATE_TRACE macro is defined, the value of each Mem is
** printed on stderr on the way into and out of sqlite3VdbeMemTranslate().
*/
/* #define TRANSLATE_TRACE 1 */

#ifndef SQLITE_OMIT_UTF16
/*
** This routine transforms the internal text encoding used by pMem to
** desiredEnc. It is an error if the string is already of the desired
** encoding, or if *pMem does not contain a string value.
*/
SQLITE_PRIVATE int sqlite3VdbeMemTranslate(Mem *pMem, u8 desiredEnc){
  int len;                    /* Maximum length of output string in bytes */
  unsigned char *zOut;                  /* Output buffer */
  unsigned char *zIn;                   /* Input iterator */
  unsigned char *zTerm;                 /* End of input */
  unsigned char *z;                     /* Output iterator */
  unsigned int c;

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( pMem->flags&MEM_Str );
  assert( pMem->enc!=desiredEnc );
  assert( pMem->enc!=0 );
  assert( pMem->n>=0 );

#if defined(TRANSLATE_TRACE) && defined(SQLITE_DEBUG)
  {
    char zBuf[100];
    sqlite3VdbeMemPrettyPrint(pMem, zBuf);
    fprintf(stderr, "INPUT:  %s\n", zBuf);
  }
#endif

  /* If the translation is between UTF-16 little and big endian, then
  ** all that is required is to swap the byte order. This case is handled
  ** differently from the others.
  */
  if( pMem->enc!=SQLITE_UTF8 && desiredEnc!=SQLITE_UTF8 ){
    u8 temp;
    int rc;
    rc = sqlite3VdbeMemMakeWriteable(pMem);
    if( rc!=SQLITE_OK ){
      assert( rc==SQLITE_NOMEM );
      return SQLITE_NOMEM;
    }
    zIn = (u8*)pMem->z;
    zTerm = &zIn[pMem->n&~1];
    while( zIn<zTerm ){
      temp = *zIn;
      *zIn = *(zIn+1);
      zIn++;
      *zIn++ = temp;
    }
    pMem->enc = desiredEnc;
    goto translate_out;
  }

  /* Set len to the maximum number of bytes required in the output buffer. */
  if( desiredEnc==SQLITE_UTF8 ){
    /* When converting from UTF-16, the maximum growth results from
    ** translating a 2-byte character to a 4-byte UTF-8 character.
    ** A single byte is required for the output string
    ** nul-terminator.
    */
    pMem->n &= ~1;
    len = pMem->n * 2 + 1;
  }else{
    /* When converting from UTF-8 to UTF-16 the maximum growth is caused
    ** when a 1-byte UTF-8 character is translated into a 2-byte UTF-16
    ** character. Two bytes are required in the output buffer for the
    ** nul-terminator.
    */
    len = pMem->n * 2 + 2;
  }

  /* Set zIn to point at the start of the input buffer and zTerm to point 1
  ** byte past the end.
  **
  ** Variable zOut is set to point at the output buffer, space obtained
  ** from sqlite3_malloc().
  */
  zIn = (u8*)pMem->z;
  zTerm = &zIn[pMem->n];
  zOut = sqlite3DbMallocRaw(pMem->db, len);
  if( !zOut ){
    return SQLITE_NOMEM;
  }
  z = zOut;

  if( pMem->enc==SQLITE_UTF8 ){
    if( desiredEnc==SQLITE_UTF16LE ){
      /* UTF-8 -> UTF-16 Little-endian */
      while( zIn<zTerm ){
        /* c = sqlite3Utf8Read(zIn, zTerm, (const u8**)&zIn); */
        READ_UTF8(zIn, zTerm, c);
        WRITE_UTF16LE(z, c);
      }
    }else{
      assert( desiredEnc==SQLITE_UTF16BE );
      /* UTF-8 -> UTF-16 Big-endian */
      while( zIn<zTerm ){
        /* c = sqlite3Utf8Read(zIn, zTerm, (const u8**)&zIn); */
        READ_UTF8(zIn, zTerm, c);
        WRITE_UTF16BE(z, c);
      }
    }
    pMem->n = (int)(z - zOut);
    *z++ = 0;
  }else{
    assert( desiredEnc==SQLITE_UTF8 );
    if( pMem->enc==SQLITE_UTF16LE ){
      /* UTF-16 Little-endian -> UTF-8 */
      while( zIn<zTerm ){
        READ_UTF16LE(zIn, zIn<zTerm, c);
        WRITE_UTF8(z, c);
      }
    }else{
      /* UTF-16 Big-endian -> UTF-8 */
      while( zIn<zTerm ){
        READ_UTF16BE(zIn, zIn<zTerm, c);
        WRITE_UTF8(z, c);
      }
    }
    pMem->n = (int)(z - zOut);
  }
  *z = 0;
  assert( (pMem->n+(desiredEnc==SQLITE_UTF8?1:2))<=len );

  sqlite3VdbeMemRelease(pMem);
  pMem->flags &= ~(MEM_Static|MEM_Dyn|MEM_Ephem);
  pMem->enc = desiredEnc;
  pMem->flags |= (MEM_Term|MEM_Dyn);
  pMem->z = (char*)zOut;
  pMem->zMalloc = pMem->z;

translate_out:
#if defined(TRANSLATE_TRACE) && defined(SQLITE_DEBUG)
  {
    char zBuf[100];
    sqlite3VdbeMemPrettyPrint(pMem, zBuf);
    fprintf(stderr, "OUTPUT: %s\n", zBuf);
  }
#endif
  return SQLITE_OK;
}

/*
** This routine checks for a byte-order mark at the beginning of the
** UTF-16 string stored in *pMem. If one is present, it is removed and
** the encoding of the Mem adjusted. This routine does not do any
** byte-swapping, it just sets Mem.enc appropriately.
**
** The allocation (static, dynamic etc.) and encoding of the Mem may be
** changed by this function.
*/
SQLITE_PRIVATE int sqlite3VdbeMemHandleBom(Mem *pMem){
  int rc = SQLITE_OK;
  u8 bom = 0;

  assert( pMem->n>=0 );
  if( pMem->n>1 ){
    u8 b1 = *(u8 *)pMem->z;
    u8 b2 = *(((u8 *)pMem->z) + 1);
    if( b1==0xFE && b2==0xFF ){
      bom = SQLITE_UTF16BE;
    }
    if( b1==0xFF && b2==0xFE ){
      bom = SQLITE_UTF16LE;
    }
  }

  if( bom ){
    rc = sqlite3VdbeMemMakeWriteable(pMem);
    if( rc==SQLITE_OK ){
      pMem->n -= 2;
      memmove(pMem->z, &pMem->z[2], pMem->n);
      pMem->z[pMem->n] = '\0';
      pMem->z[pMem->n+1] = '\0';
      pMem->flags |= MEM_Term;
      pMem->enc = bom;
    }
  }
  return rc;
}
#endif /* SQLITE_OMIT_UTF16 */

/*
** pZ is a UTF-8 encoded unicode string. If nByte is less than zero,
** return the number of unicode characters in pZ up to (but not including)
** the first 0x00 byte. If nByte is not less than zero, return the
** number of unicode characters in the first nByte of pZ (or up to
** the first 0x00, whichever comes first).
*/
SQLITE_PRIVATE int sqlite3Utf8CharLen(const char *zIn, int nByte){
  int r = 0;
  const u8 *z = (const u8*)zIn;
  const u8 *zTerm;
  if( nByte>=0 ){
    zTerm = &z[nByte];
  }else{
    zTerm = (const u8*)(-1);
  }
  assert( z<=zTerm );
  while( *z!=0 && z<zTerm ){
    SQLITE_SKIP_UTF8(z);
    r++;
  }
  return r;
}

/* This test function is not currently used by the automated test-suite.
** Hence it is only available in debug builds.
*/
#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
/*
** Translate UTF-8 to UTF-8.
**
** This has the effect of making sure that the string is well-formed
** UTF-8.  Miscoded characters are removed.
**
** The translation is done in-place (since it is impossible for the
** correct UTF-8 encoding to be longer than a malformed encoding).
*/
SQLITE_PRIVATE int sqlite3Utf8To8(unsigned char *zIn){
  unsigned char *zOut = zIn;
  unsigned char *zStart = zIn;
  u32 c;

  while( zIn[0] ){
    c = sqlite3Utf8Read(zIn, (const u8**)&zIn);
    if( c!=0xfffd ){
      WRITE_UTF8(zOut, c);
    }
  }
  *zOut = 0;
  return (int)(zOut - zStart);
}
#endif

#ifndef SQLITE_OMIT_UTF16
/*
** Convert a UTF-16 string in the native encoding into a UTF-8 string.
** Memory to hold the UTF-8 string is obtained from sqlite3_malloc and must
** be freed by the calling function.
**
** NULL is returned if there is an allocation error.
*/
SQLITE_PRIVATE char *sqlite3Utf16to8(sqlite3 *db, const void *z, int nByte){
  Mem m;
  memset(&m, 0, sizeof(m));
  m.db = db;
  sqlite3VdbeMemSetStr(&m, z, nByte, SQLITE_UTF16NATIVE, SQLITE_STATIC);
  sqlite3VdbeChangeEncoding(&m, SQLITE_UTF8);
  if( db->mallocFailed ){
    sqlite3VdbeMemRelease(&m);
    m.z = 0;
  }
  assert( (m.flags & MEM_Term)!=0 || db->mallocFailed );
  assert( (m.flags & MEM_Str)!=0 || db->mallocFailed );
  return (m.flags & MEM_Dyn)!=0 ? m.z : sqlite3DbStrDup(db, m.z);
}

/*
** Convert a UTF-8 string to the UTF-16 encoding specified by parameter
** enc. A pointer to the new string is returned, and the value of *pnOut
** is set to the length of the returned string in bytes. The call should
** arrange to call sqlite3DbFree() on the returned pointer when it is
** no longer required.
**
** If a malloc failure occurs, NULL is returned and the db.mallocFailed
** flag set.
*/
#ifdef SQLITE_ENABLE_STAT2
SQLITE_PRIVATE char *sqlite3Utf8to16(sqlite3 *db, u8 enc, char *z, int n, int *pnOut){
  Mem m;
  memset(&m, 0, sizeof(m));
  m.db = db;
  sqlite3VdbeMemSetStr(&m, z, n, SQLITE_UTF8, SQLITE_STATIC);
  if( sqlite3VdbeMemTranslate(&m, enc) ){
    assert( db->mallocFailed );
    return 0;
  }
  assert( m.z==m.zMalloc );
  *pnOut = m.n;
  return m.z;
}
#endif

/*
** zIn is a UTF-16 encoded unicode string at least nChar characters long.
** Return the number of bytes in the first nChar unicode characters
** in pZ.  nChar must be non-negative.
*/
SQLITE_PRIVATE int sqlite3Utf16ByteLen(const void *zIn, int nChar){
  int c;
  unsigned char const *z = zIn;
  int n = 0;

  if( SQLITE_UTF16NATIVE==SQLITE_UTF16BE ){
    while( n<nChar ){
      READ_UTF16BE(z, 1, c);
      n++;
    }
  }else{
    while( n<nChar ){
      READ_UTF16LE(z, 1, c);
      n++;
    }
  }
  return (int)(z-(unsigned char const *)zIn);
}

#if defined(SQLITE_TEST)
/*
** This routine is called from the TCL test function "translate_selftest".
** It checks that the primitives for serializing and deserializing
** characters in each encoding are inverses of each other.
*/
SQLITE_PRIVATE void sqlite3UtfSelfTest(void){
  unsigned int i, t;
  unsigned char zBuf[20];
  unsigned char *z;
  int n;
  unsigned int c;

  for(i=0; i<0x00110000; i++){
    z = zBuf;
    WRITE_UTF8(z, i);
    n = (int)(z-zBuf);
    assert( n>0 && n<=4 );
    z[0] = 0;
    z = zBuf;
    c = sqlite3Utf8Read(z, (const u8**)&z);
    t = i;
    if( i>=0xD800 && i<=0xDFFF ) t = 0xFFFD;
    if( (i&0xFFFFFFFE)==0xFFFE ) t = 0xFFFD;
    assert( c==t );
    assert( (z-zBuf)==n );
  }
  for(i=0; i<0x00110000; i++){
    if( i>=0xD800 && i<0xE000 ) continue;
    z = zBuf;
    WRITE_UTF16LE(z, i);
    n = (int)(z-zBuf);
    assert( n>0 && n<=4 );
    z[0] = 0;
    z = zBuf;
    READ_UTF16LE(z, 1, c);
    assert( c==i );
    assert( (z-zBuf)==n );
  }
  for(i=0; i<0x00110000; i++){
    if( i>=0xD800 && i<0xE000 ) continue;
    z = zBuf;
    WRITE_UTF16BE(z, i);
    n = (int)(z-zBuf);
    assert( n>0 && n<=4 );
    z[0] = 0;
    z = zBuf;
    READ_UTF16BE(z, 1, c);
    assert( c==i );
    assert( (z-zBuf)==n );
  }
}
#endif /* SQLITE_TEST */
#endif /* SQLITE_OMIT_UTF16 */

/************** End of utf.c *************************************************/
/************** Begin file util.c ********************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
*/
#ifdef SQLITE_HAVE_ISNAN
# include <math.h>
#endif

/*
** Routine needed to support the testcase() macro.
*/
#ifdef SQLITE_COVERAGE_TEST
SQLITE_PRIVATE void sqlite3Coverage(int x){
  static int dummy = 0;
  dummy += x;
}
#endif

/*
** Return true if the floating point value is Not a Number (NaN).
**
** Use the math library isnan() function if compiled with SQLITE_HAVE_ISNAN.
** Otherwise, we have our own implementation that works on most systems.
*/
SQLITE_PRIVATE int sqlite3IsNaN(double x){
  int rc;   /* The value return */
#if !defined(SQLITE_HAVE_ISNAN)
  /*
  ** Systems that support the isnan() library function should probably
  ** make use of it by compiling with -DSQLITE_HAVE_ISNAN.  But we have
  ** found that many systems do not have a working isnan() function so
  ** this implementation is provided as an alternative.
  **
  ** This NaN test sometimes fails if compiled on GCC with -ffast-math.
  ** On the other hand, the use of -ffast-math comes with the following
  ** warning:
  **
  **      This option [-ffast-math] should never be turned on by any
  **      -O option since it can result in incorrect output for programs
  **      which depend on an exact implementation of IEEE or ISO
  **      rules/specifications for math functions.
  **
  ** Under MSVC, this NaN test may fail if compiled with a floating-
  ** point precision mode other than /fp:precise.  From the MSDN
  ** documentation:
  **
  **      The compiler [with /fp:precise] will properly handle comparisons
  **      involving NaN. For example, x != x evaluates to true if x is NaN
  **      ...
  */
#ifdef __FAST_MATH__
# error SQLite will not work correctly with the -ffast-math option of GCC.
#endif
  volatile double y = x;
  volatile double z = y;
  rc = (y!=z);
#else  /* if defined(SQLITE_HAVE_ISNAN) */
  rc = isnan(x);
#endif /* SQLITE_HAVE_ISNAN */
  testcase( rc );
  return rc;
}

/*
** Compute a string length that is limited to what can be stored in
** lower 30 bits of a 32-bit signed integer.
**
** The value returned will never be negative.  Nor will it ever be greater
** than the actual length of the string.  For very long strings (greater
** than 1GiB) the value returned might be less than the true string length.
*/
SQLITE_PRIVATE int sqlite3Strlen30(const char *z){
  const char *z2 = z;
  if( z==0 ) return 0;
  while( *z2 ){ z2++; }
  return 0x3fffffff & (int)(z2 - z);
}

/*
** Set the most recent error code and error string for the sqlite
** handle "db". The error code is set to "err_code".
**
** If it is not NULL, string zFormat specifies the format of the
** error string in the style of the printf functions: The following
** format characters are allowed:
**
**      %s      Insert a string
**      %z      A string that should be freed after use
**      %d      Insert an integer
**      %T      Insert a token
**      %S      Insert the first element of a SrcList
**
** zFormat and any string tokens that follow it are assumed to be
** encoded in UTF-8.
**
** To clear the most recent error for sqlite handle "db", sqlite3Error
** should be called with err_code set to SQLITE_OK and zFormat set
** to NULL.
*/
SQLITE_PRIVATE void sqlite3Error(sqlite3 *db, int err_code, const char *zFormat, ...){
  if( db && (db->pErr || (db->pErr = sqlite3ValueNew(db))!=0) ){
    db->errCode = err_code;
    if( zFormat ){
      char *z;
      va_list ap;
      va_start(ap, zFormat);
      z = sqlite3VMPrintf(db, zFormat, ap);
      va_end(ap);
      sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, SQLITE_DYNAMIC);
    }else{
      sqlite3ValueSetStr(db->pErr, 0, 0, SQLITE_UTF8, SQLITE_STATIC);
    }
  }
}

/*
** Add an error message to pParse->zErrMsg and increment pParse->nErr.
** The following formatting characters are allowed:
**
**      %s      Insert a string
**      %z      A string that should be freed after use
**      %d      Insert an integer
**      %T      Insert a token
**      %S      Insert the first element of a SrcList
**
** This function should be used to report any error that occurs whilst
** compiling an SQL statement (i.e. within sqlite3_prepare()). The
** last thing the sqlite3_prepare() function does is copy the error
** stored by this function into the database handle using sqlite3Error().
** Function sqlite3Error() should be used during statement execution
** (sqlite3_step() etc.).
*/
SQLITE_PRIVATE void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
  char *zMsg;
  va_list ap;
  sqlite3 *db = pParse->db;
  va_start(ap, zFormat);
  zMsg = sqlite3VMPrintf(db, zFormat, ap);
  va_end(ap);
  if( db->suppressErr ){
    sqlite3DbFree(db, zMsg);
  }else{
    pParse->nErr++;
    sqlite3DbFree(db, pParse->zErrMsg);
    pParse->zErrMsg = zMsg;
    pParse->rc = SQLITE_ERROR;
  }
}

/*
** Convert an SQL-style quoted string into a normal string by removing
** the quote characters.  The conversion is done in-place.  If the
** input does not begin with a quote character, then this routine
** is a no-op.
**
** The input string must be zero-terminated.  A new zero-terminator
** is added to the dequoted string.
**
** The return value is -1 if no dequoting occurs or the length of the
** dequoted string, exclusive of the zero terminator, if dequoting does
** occur.
**
** 2002-Feb-14: This routine is extended to remove MS-Access style
** brackets from around identifers.  For example:  "[a-b-c]" becomes
** "a-b-c".
*/
SQLITE_PRIVATE int sqlite3Dequote(char *z){
  char quote;
  int i, j;
  if( z==0 ) return -1;
  quote = z[0];
  switch( quote ){
    case '\'':  break;
    case '"':   break;
    case '`':   break;                /* For MySQL compatibility */
    case '[':   quote = ']';  break;  /* For MS SqlServer compatibility */
    default:    return -1;
  }
  for(i=1, j=0; ALWAYS(z[i]); i++){
    if( z[i]==quote ){
      if( z[i+1]==quote ){
        z[j++] = quote;
        i++;
      }else{
        break;
      }
    }else{
      z[j++] = z[i];
    }
  }
  z[j] = 0;
  return j;
}

/* Convenient short-hand */
#define UpperToLower sqlite3UpperToLower

/*
** Some systems have stricmp().  Others have strcasecmp().  Because
** there is no consistency, we will define our own.
*/
SQLITE_PRIVATE int sqlite3StrICmp(const char *zLeft, const char *zRight){
  register unsigned char *a, *b;
  a = (unsigned char *)zLeft;
  b = (unsigned char *)zRight;
  while( *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
  return UpperToLower[*a] - UpperToLower[*b];
}
SQLITE_API int sqlite3_strnicmp(const char *zLeft, const char *zRight, int N){
  register unsigned char *a, *b;
  a = (unsigned char *)zLeft;
  b = (unsigned char *)zRight;
  while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
  return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
}

/*
** Return TRUE if z is a pure numeric string.  Return FALSE and leave
** *realnum unchanged if the string contains any character which is not
** part of a number.
**
** If the string is pure numeric, set *realnum to TRUE if the string
** contains the '.' character or an "E+000" style exponentiation suffix.
** Otherwise set *realnum to FALSE.  Note that just becaue *realnum is
** false does not mean that the number can be successfully converted into
** an integer - it might be too big.
**
** An empty string is considered non-numeric.
*/
SQLITE_PRIVATE int sqlite3IsNumber(const char *z, int *realnum, u8 enc){
  int incr = (enc==SQLITE_UTF8?1:2);
  if( enc==SQLITE_UTF16BE ) z++;
  if( *z=='-' || *z=='+' ) z += incr;
  if( !sqlite3Isdigit(*z) ){
    return 0;
  }
  z += incr;
  *realnum = 0;
  while( sqlite3Isdigit(*z) ){ z += incr; }
  if( *z=='.' ){
    z += incr;
    if( !sqlite3Isdigit(*z) ) return 0;
    while( sqlite3Isdigit(*z) ){ z += incr; }
    *realnum = 1;
  }
  if( *z=='e' || *z=='E' ){
    z += incr;
    if( *z=='+' || *z=='-' ) z += incr;
    if( !sqlite3Isdigit(*z) ) return 0;
    while( sqlite3Isdigit(*z) ){ z += incr; }
    *realnum = 1;
  }
  return *z==0;
}

/*
** The string z[] is an ASCII representation of a real number.
** Convert this string to a double.
**
** This routine assumes that z[] really is a valid number.  If it
** is not, the result is undefined.
**
** This routine is used instead of the library atof() function because
** the library atof() might want to use "," as the decimal point instead
** of "." depending on how locale is set.  But that would cause problems
** for SQL.  So this routine always uses "." regardless of locale.
*/
SQLITE_PRIVATE int sqlite3AtoF(const char *z, double *pResult){
#ifndef SQLITE_OMIT_FLOATING_POINT
  const char *zBegin = z;
  /* sign * significand * (10 ^ (esign * exponent)) */
  int sign = 1;   /* sign of significand */
  i64 s = 0;      /* significand */
  int d = 0;      /* adjust exponent for shifting decimal point */
  int esign = 1;  /* sign of exponent */
  int e = 0;      /* exponent */
  double result;
  int nDigits = 0;

  /* skip leading spaces */
  while( sqlite3Isspace(*z) ) z++;
  /* get sign of significand */
  if( *z=='-' ){
    sign = -1;
    z++;
  }else if( *z=='+' ){
    z++;
  }
  /* skip leading zeroes */
  while( z[0]=='0' ) z++, nDigits++;

  /* copy max significant digits to significand */
  while( sqlite3Isdigit(*z) && s<((LARGEST_INT64-9)/10) ){
    s = s*10 + (*z - '0');
    z++, nDigits++;
  }
  /* skip non-significant significand digits
  ** (increase exponent by d to shift decimal left) */
  while( sqlite3Isdigit(*z) ) z++, nDigits++, d++;

  /* if decimal point is present */
  if( *z=='.' ){
    z++;
    /* copy digits from after decimal to significand
    ** (decrease exponent by d to shift decimal right) */
    while( sqlite3Isdigit(*z) && s<((LARGEST_INT64-9)/10) ){
      s = s*10 + (*z - '0');
      z++, nDigits++, d--;
    }
    /* skip non-significant digits */
    while( sqlite3Isdigit(*z) ) z++, nDigits++;
  }

  /* if exponent is present */
  if( *z=='e' || *z=='E' ){
    z++;
    /* get sign of exponent */
    if( *z=='-' ){
      esign = -1;
      z++;
    }else if( *z=='+' ){
      z++;
    }
    /* copy digits to exponent */
    while( sqlite3Isdigit(*z) ){
      e = e*10 + (*z - '0');
      z++;
    }
  }

  /* adjust exponent by d, and update sign */
  e = (e*esign) + d;
  if( e<0 ) {
    esign = -1;
    e *= -1;
  } else {
    esign = 1;
  }

  /* if 0 significand */
  if( !s ) {
    /* In the IEEE 754 standard, zero is signed.
    ** Add the sign if we've seen at least one digit */
    result = (sign<0 && nDigits) ? -(double)0 : (double)0;
  } else {
    /* attempt to reduce exponent */
    if( esign>0 ){
      while( s<(LARGEST_INT64/10) && e>0 ) e--,s*=10;
    }else{
      while( !(s%10) && e>0 ) e--,s/=10;
    }

    /* adjust the sign of significand */
    s = sign<0 ? -s : s;

    /* if exponent, scale significand as appropriate
    ** and store in result. */
    if( e ){
      double scale = 1.0;
      /* attempt to handle extremely small/large numbers better */
      if( e>307 && e<342 ){
        while( e%308 ) { scale *= 1.0e+1; e -= 1; }
        if( esign<0 ){
          result = s / scale;
          result /= 1.0e+308;
        }else{
          result = s * scale;
          result *= 1.0e+308;
        }
      }else{
        /* 1.0e+22 is the largest power of 10 than can be
        ** represented exactly. */
        while( e%22 ) { scale *= 1.0e+1; e -= 1; }
        while( e>0 ) { scale *= 1.0e+22; e -= 22; }
        if( esign<0 ){
          result = s / scale;
        }else{
          result = s * scale;
        }
      }
    } else {
      result = (double)s;
    }
  }

  /* store the result */
  *pResult = result;

  /* return number of characters used */
  return (int)(z - zBegin);
#else
  return sqlite3Atoi64(z, pResult);
#endif /* SQLITE_OMIT_FLOATING_POINT */
}

/*
** Compare the 19-character string zNum against the text representation
** value 2^63:  9223372036854775808.  Return negative, zero, or positive
** if zNum is less than, equal to, or greater than the string.
**
** Unlike memcmp() this routine is guaranteed to return the difference
** in the values of the last digit if the only difference is in the
** last digit.  So, for example,
**
**      compare2pow63("9223372036854775800")
**
** will return -8.
*/
static int compare2pow63(const char *zNum){
  int c;
  c = memcmp(zNum,"922337203685477580",18)*10;
  if( c==0 ){
    c = zNum[18] - '8';
  }
  return c;
}


/*
** Return TRUE if zNum is a 64-bit signed integer and write
** the value of the integer into *pNum.  If zNum is not an integer
** or is an integer that is too large to be expressed with 64 bits,
** then return false.
**
** When this routine was originally written it dealt with only
** 32-bit numbers.  At that time, it was much faster than the
** atoi() library routine in RedHat 7.2.
*/
SQLITE_PRIVATE int sqlite3Atoi64(const char *zNum, i64 *pNum){
  i64 v = 0;
  int neg;
  int i, c;
  const char *zStart;
  while( sqlite3Isspace(*zNum) ) zNum++;
  if( *zNum=='-' ){
    neg = 1;
    zNum++;
  }else if( *zNum=='+' ){
    neg = 0;
    zNum++;
  }else{
    neg = 0;
  }
  zStart = zNum;
  while( zNum[0]=='0' ){ zNum++; } /* Skip over leading zeros. Ticket #2454 */
  for(i=0; (c=zNum[i])>='0' && c<='9'; i++){
    v = v*10 + c - '0';
  }
  *pNum = neg ? -v : v;
  if( c!=0 || (i==0 && zStart==zNum) || i>19 ){
    /* zNum is empty or contains non-numeric text or is longer
    ** than 19 digits (thus guaranting that it is too large) */
    return 0;
  }else if( i<19 ){
    /* Less than 19 digits, so we know that it fits in 64 bits */
    return 1;
  }else{
    /* 19-digit numbers must be no larger than 9223372036854775807 if positive
    ** or 9223372036854775808 if negative.  Note that 9223372036854665808
    ** is 2^63. */
    return compare2pow63(zNum)<neg;
  }
}

/*
** The string zNum represents an unsigned integer.  The zNum string
** consists of one or more digit characters and is terminated by
** a zero character.  Any stray characters in zNum result in undefined
** behavior.
**
** If the unsigned integer that zNum represents will fit in a
** 64-bit signed integer, return TRUE.  Otherwise return FALSE.
**
** If the negFlag parameter is true, that means that zNum really represents
** a negative number.  (The leading "-" is omitted from zNum.)  This
** parameter is needed to determine a boundary case.  A string
** of "9223373036854775808" returns false if negFlag is false or true
** if negFlag is true.
**
** Leading zeros are ignored.
*/
SQLITE_PRIVATE int sqlite3FitsIn64Bits(const char *zNum, int negFlag){
  int i;
  int neg = 0;

  assert( zNum[0]>='0' && zNum[0]<='9' ); /* zNum is an unsigned number */

  if( negFlag ) neg = 1-neg;
  while( *zNum=='0' ){
    zNum++;   /* Skip leading zeros.  Ticket #2454 */
  }
  for(i=0; zNum[i]; i++){ assert( zNum[i]>='0' && zNum[i]<='9' ); }
  if( i<19 ){
    /* Guaranteed to fit if less than 19 digits */
    return 1;
  }else if( i>19 ){
    /* Guaranteed to be too big if greater than 19 digits */
    return 0;
  }else{
    /* Compare against 2^63. */
    return compare2pow63(zNum)<neg;
  }
}

/*
** If zNum represents an integer that will fit in 32-bits, then set
** *pValue to that integer and return true.  Otherwise return false.
**
** Any non-numeric characters that following zNum are ignored.
** This is different from sqlite3Atoi64() which requires the
** input number to be zero-terminated.
*/
SQLITE_PRIVATE int sqlite3GetInt32(const char *zNum, int *pValue){
  sqlite_int64 v = 0;
  int i, c;
  int neg = 0;
  if( zNum[0]=='-' ){
    neg = 1;
    zNum++;
  }else if( zNum[0]=='+' ){
    zNum++;
  }
  while( zNum[0]=='0' ) zNum++;
  for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){
    v = v*10 + c;
  }

  /* The longest decimal representation of a 32 bit integer is 10 digits:
  **
  **             1234567890
  **     2^31 -> 2147483648
  */
  if( i>10 ){
    return 0;
  }
  if( v-neg>2147483647 ){
    return 0;
  }
  if( neg ){
    v = -v;
  }
  *pValue = (int)v;
  return 1;
}

/*
** The variable-length integer encoding is as follows:
**
** KEY:
**         A = 0xxxxxxx    7 bits of data and one flag bit
**         B = 1xxxxxxx    7 bits of data and one flag bit
**         C = xxxxxxxx    8 bits of data
**
**  7 bits - A
** 14 bits - BA
** 21 bits - BBA
** 28 bits - BBBA
** 35 bits - BBBBA
** 42 bits - BBBBBA
** 49 bits - BBBBBBA
** 56 bits - BBBBBBBA
** 64 bits - BBBBBBBBC
*/

/*
** Write a 64-bit variable-length integer to memory starting at p[0].
** The length of data write will be between 1 and 9 bytes.  The number
** of bytes written is returned.
**
** A variable-length integer consists of the lower 7 bits of each byte
** for all bytes that have the 8th bit set and one byte with the 8th
** bit clear.  Except, if we get to the 9th byte, it stores the full
** 8 bits and is the last byte.
*/
SQLITE_PRIVATE int sqlite3PutVarint(unsigned char *p, u64 v){
  int i, j, n;
  u8 buf[10];
  if( v & (((u64)0xff000000)<<32) ){
    p[8] = (u8)v;
    v >>= 8;
    for(i=7; i>=0; i--){
      p[i] = (u8)((v & 0x7f) | 0x80);
      v >>= 7;
    }
    return 9;
  }
  n = 0;
  do{
    buf[n++] = (u8)((v & 0x7f) | 0x80);
    v >>= 7;
  }while( v!=0 );
  buf[0] &= 0x7f;
  assert( n<=9 );
  for(i=0, j=n-1; j>=0; j--, i++){
    p[i] = buf[j];
  }
  return n;
}

/*
** This routine is a faster version of sqlite3PutVarint() that only
** works for 32-bit positive integers and which is optimized for
** the common case of small integers.  A MACRO version, putVarint32,
** is provided which inlines the single-byte case.  All code should use
** the MACRO version as this function assumes the single-byte case has
** already been handled.
*/
SQLITE_PRIVATE int sqlite3PutVarint32(unsigned char *p, u32 v){
#ifndef putVarint32
  if( (v & ~0x7f)==0 ){
    p[0] = v;
    return 1;
  }
#endif
  if( (v & ~0x3fff)==0 ){
    p[0] = (u8)((v>>7) | 0x80);
    p[1] = (u8)(v & 0x7f);
    return 2;
  }
  return sqlite3PutVarint(p, v);
}

/*
** Read a 64-bit variable-length integer from memory starting at p[0].
** Return the number of bytes read.  The value is stored in *v.
*/
SQLITE_PRIVATE u8 sqlite3GetVarint(const unsigned char *p, u64 *v){
  u32 a,b,s;

  a = *p;
  /* a: p0 (unmasked) */
  if (!(a&0x80))
  {
    *v = a;
    return 1;
  }

  p++;
  b = *p;
  /* b: p1 (unmasked) */
  if (!(b&0x80))
  {
    a &= 0x7f;
    a = a<<7;
    a |= b;
    *v = a;
    return 2;
  }

  p++;
  a = a<<14;
  a |= *p;
  /* a: p0<<14 | p2 (unmasked) */
  if (!(a&0x80))
  {
    a &= (0x7f<<14)|(0x7f);
    b &= 0x7f;
    b = b<<7;
    a |= b;
    *v = a;
    return 3;
  }

  /* CSE1 from below */
  a &= (0x7f<<14)|(0x7f);
  p++;
  b = b<<14;
  b |= *p;
  /* b: p1<<14 | p3 (unmasked) */
  if (!(b&0x80))
  {
    b &= (0x7f<<14)|(0x7f);
    /* moved CSE1 up */
    /* a &= (0x7f<<14)|(0x7f); */
    a = a<<7;
    a |= b;
    *v = a;
    return 4;
  }

  /* a: p0<<14 | p2 (masked) */
  /* b: p1<<14 | p3 (unmasked) */
  /* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
  /* moved CSE1 up */
  /* a &= (0x7f<<14)|(0x7f); */
  b &= (0x7f<<14)|(0x7f);
  s = a;
  /* s: p0<<14 | p2 (masked) */

  p++;
  a = a<<14;
  a |= *p;
  /* a: p0<<28 | p2<<14 | p4 (unmasked) */
  if (!(a&0x80))
  {
    /* we can skip these cause they were (effectively) done above in calc'ing s */
    /* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
    /* b &= (0x7f<<14)|(0x7f); */
    b = b<<7;
    a |= b;
    s = s>>18;
    *v = ((u64)s)<<32 | a;
    return 5;
  }

  /* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
  s = s<<7;
  s |= b;
  /* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */

  p++;
  b = b<<14;
  b |= *p;
  /* b: p1<<28 | p3<<14 | p5 (unmasked) */
  if (!(b&0x80))
  {
    /* we can skip this cause it was (effectively) done above in calc'ing s */
    /* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
    a &= (0x7f<<14)|(0x7f);
    a = a<<7;
    a |= b;
    s = s>>18;
    *v = ((u64)s)<<32 | a;
    return 6;
  }

  p++;
  a = a<<14;
  a |= *p;
  /* a: p2<<28 | p4<<14 | p6 (unmasked) */
  if (!(a&0x80))
  {
    a &= (0x1f<<28)|(0x7f<<14)|(0x7f);
    b &= (0x7f<<14)|(0x7f);
    b = b<<7;
    a |= b;
    s = s>>11;
    *v = ((u64)s)<<32 | a;
    return 7;
  }

  /* CSE2 from below */
  a &= (0x7f<<14)|(0x7f);
  p++;
  b = b<<14;
  b |= *p;
  /* b: p3<<28 | p5<<14 | p7 (unmasked) */
  if (!(b&0x80))
  {
    b &= (0x1f<<28)|(0x7f<<14)|(0x7f);
    /* moved CSE2 up */
    /* a &= (0x7f<<14)|(0x7f); */
    a = a<<7;
    a |= b;
    s = s>>4;
    *v = ((u64)s)<<32 | a;
    return 8;
  }

  p++;
  a = a<<15;
  a |= *p;
  /* a: p4<<29 | p6<<15 | p8 (unmasked) */

  /* moved CSE2 up */
  /* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */
  b &= (0x7f<<14)|(0x7f);
  b = b<<8;
  a |= b;

  s = s<<4;
  b = p[-4];
  b &= 0x7f;
  b = b>>3;
  s |= b;

  *v = ((u64)s)<<32 | a;

  return 9;
}

/*
** Read a 32-bit variable-length integer from memory starting at p[0].
** Return the number of bytes read.  The value is stored in *v.
**
** If the varint stored in p[0] is larger than can fit in a 32-bit unsigned
** integer, then set *v to 0xffffffff.
**
** A MACRO version, getVarint32, is provided which inlines the
** single-byte case.  All code should use the MACRO version as
** this function assumes the single-byte case has already been handled.
*/
SQLITE_PRIVATE u8 sqlite3GetVarint32(const unsigned char *p, u32 *v){
  u32 a,b;

  /* The 1-byte case.  Overwhelmingly the most common.  Handled inline
  ** by the getVarin32() macro */
  a = *p;
  /* a: p0 (unmasked) */
#ifndef getVarint32
  if (!(a&0x80))
  {
    /* Values between 0 and 127 */
    *v = a;
    return 1;
  }
#endif

  /* The 2-byte case */
  p++;
  b = *p;
  /* b: p1 (unmasked) */
  if (!(b&0x80))
  {
    /* Values between 128 and 16383 */
    a &= 0x7f;
    a = a<<7;
    *v = a | b;
    return 2;
  }

  /* The 3-byte case */
  p++;
  a = a<<14;
  a |= *p;
  /* a: p0<<14 | p2 (unmasked) */
  if (!(a&0x80))
  {
    /* Values between 16384 and 2097151 */
    a &= (0x7f<<14)|(0x7f);
    b &= 0x7f;
    b = b<<7;
    *v = a | b;
    return 3;
  }

  /* A 32-bit varint is used to store size information in btrees.
  ** Objects are rarely larger than 2MiB limit of a 3-byte varint.
  ** A 3-byte varint is sufficient, for example, to record the size
  ** of a 1048569-byte BLOB or string.
  **
  ** We only unroll the first 1-, 2-, and 3- byte cases.  The very
  ** rare larger cases can be handled by the slower 64-bit varint
  ** routine.
  */
#if 1
  {
    u64 v64;
    u8 n;

    p -= 2;
    n = sqlite3GetVarint(p, &v64);
    assert( n>3 && n<=9 );
    if( (v64 & SQLITE_MAX_U32)!=v64 ){
      *v = 0xffffffff;
    }else{
      *v = (u32)v64;
    }
    return n;
  }

#else
  /* For following code (kept for historical record only) shows an
  ** unrolling for the 3- and 4-byte varint cases.  This code is
  ** slightly faster, but it is also larger and much harder to test.
  */
  p++;
  b = b<<14;
  b |= *p;
  /* b: p1<<14 | p3 (unmasked) */
  if (!(b&0x80))
  {
    /* Values between 2097152 and 268435455 */
    b &= (0x7f<<14)|(0x7f);
    a &= (0x7f<<14)|(0x7f);
    a = a<<7;
    *v = a | b;
    return 4;
  }

  p++;
  a = a<<14;
  a |= *p;
  /* a: p0<<28 | p2<<14 | p4 (unmasked) */
  if (!(a&0x80))
  {
    /* Walues  between 268435456 and 34359738367 */
    a &= (0x1f<<28)|(0x7f<<14)|(0x7f);
    b &= (0x1f<<28)|(0x7f<<14)|(0x7f);
    b = b<<7;
    *v = a | b;
    return 5;
  }

  /* We can only reach this point when reading a corrupt database
  ** file.  In that case we are not in any hurry.  Use the (relatively
  ** slow) general-purpose sqlite3GetVarint() routine to extract the
  ** value. */
  {
    u64 v64;
    u8 n;

    p -= 4;
    n = sqlite3GetVarint(p, &v64);
    assert( n>5 && n<=9 );
    *v = (u32)v64;
    return n;
  }
#endif
}

/*
** Return the number of bytes that will be needed to store the given
** 64-bit integer.
*/
SQLITE_PRIVATE int sqlite3VarintLen(u64 v){
  int i = 0;
  do{
    i++;
    v >>= 7;
  }while( v!=0 && ALWAYS(i<9) );
  return i;
}


/*
** Read or write a four-byte big-endian integer value.
*/
SQLITE_PRIVATE u32 sqlite3Get4byte(const u8 *p){
  return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
}
SQLITE_PRIVATE void sqlite3Put4byte(unsigned char *p, u32 v){
  p[0] = (u8)(v>>24);
  p[1] = (u8)(v>>16);
  p[2] = (u8)(v>>8);
  p[3] = (u8)v;
}



#if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
/*
** Translate a single byte of Hex into an integer.
** This routine only works if h really is a valid hexadecimal
** character:  0..9a..fA..F
*/
static u8 hexToInt(int h){
  assert( (h>='0' && h<='9') ||  (h>='a' && h<='f') ||  (h>='A' && h<='F') );
#ifdef SQLITE_ASCII
  h += 9*(1&(h>>6));
#endif
#ifdef SQLITE_EBCDIC
  h += 9*(1&~(h>>4));
#endif
  return (u8)(h & 0xf);
}
#endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */

#if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
/*
** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
** value.  Return a pointer to its binary value.  Space to hold the
** binary value has been obtained from malloc and must be freed by
** the calling routine.
*/
SQLITE_PRIVATE void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){
  char *zBlob;
  int i;

  zBlob = (char *)sqlite3DbMallocRaw(db, n/2 + 1);
  n--;
  if( zBlob ){
    for(i=0; i<n; i+=2){
      zBlob[i/2] = (hexToInt(z[i])<<4) | hexToInt(z[i+1]);
    }
    zBlob[i/2] = 0;
  }
  return zBlob;
}
#endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */

/*
** Log an error that is an API call on a connection pointer that should
** not have been used.  The "type" of connection pointer is given as the
** argument.  The zType is a word like "NULL" or "closed" or "invalid".
*/
static void logBadConnection(const char *zType){
  sqlite3_log(SQLITE_MISUSE,
     "API call with %s database connection pointer",
     zType
  );
}

/*
** Check to make sure we have a valid db pointer.  This test is not
** foolproof but it does provide some measure of protection against
** misuse of the interface such as passing in db pointers that are
** NULL or which have been previously closed.  If this routine returns
** 1 it means that the db pointer is valid and 0 if it should not be
** dereferenced for any reason.  The calling function should invoke
** SQLITE_MISUSE immediately.
**
** sqlite3SafetyCheckOk() requires that the db pointer be valid for
** use.  sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to
** open properly and is not fit for general use but which can be
** used as an argument to sqlite3_errmsg() or sqlite3_close().
*/
SQLITE_PRIVATE int sqlite3SafetyCheckOk(sqlite3 *db){
  u32 magic;
  if( db==0 ){
    logBadConnection("NULL");
    return 0;
  }
  magic = db->magic;
  if( magic!=SQLITE_MAGIC_OPEN ){
    if( !sqlite3SafetyCheckSickOrOk(db) ){
      logBadConnection("unopened");
    }
    return 0;
  }else{
    return 1;
  }
}
SQLITE_PRIVATE int sqlite3SafetyCheckSickOrOk(sqlite3 *db){
  u32 magic;
  magic = db->magic;
  if( magic!=SQLITE_MAGIC_SICK &&
      magic!=SQLITE_MAGIC_OPEN &&
      magic!=SQLITE_MAGIC_BUSY ){
    logBadConnection("invalid");
    return 0;
  }else{
    return 1;
  }
}

/************** End of util.c ************************************************/
/************** Begin file hash.c ********************************************/
/*
** 2001 September 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the implementation of generic hash-tables
** used in SQLite.
*/

/* Turn bulk memory into a hash table object by initializing the
** fields of the Hash structure.
**
** "pNew" is a pointer to the hash table that is to be initialized.
*/
SQLITE_PRIVATE void sqlite3HashInit(Hash *pNew){
  assert( pNew!=0 );
  pNew->first = 0;
  pNew->count = 0;
  pNew->htsize = 0;
  pNew->ht = 0;
}

/* Remove all entries from a hash table.  Reclaim all memory.
** Call this routine to delete a hash table or to reset a hash table
** to the empty state.
*/
SQLITE_PRIVATE void sqlite3HashClear(Hash *pH){
  HashElem *elem;         /* For looping over all elements of the table */

  assert( pH!=0 );
  elem = pH->first;
  pH->first = 0;
  sqlite3_free(pH->ht);
  pH->ht = 0;
  pH->htsize = 0;
  while( elem ){
    HashElem *next_elem = elem->next;
    sqlite3_free(elem);
    elem = next_elem;
  }
  pH->count = 0;
}

/*
** The hashing function.
*/
static unsigned int strHash(const char *z, int nKey){
  int h = 0;
  assert( nKey>=0 );
  while( nKey > 0  ){
    h = (h<<3) ^ h ^ sqlite3UpperToLower[(unsigned char)*z++];
    nKey--;
  }
  return h;
}


/* Link pNew element into the hash table pH.  If pEntry!=0 then also
** insert pNew into the pEntry hash bucket.
*/
static void insertElement(
  Hash *pH,              /* The complete hash table */
  struct _ht *pEntry,    /* The entry into which pNew is inserted */
  HashElem *pNew         /* The element to be inserted */
){
  HashElem *pHead;       /* First element already in pEntry */
  if( pEntry ){
    pHead = pEntry->count ? pEntry->chain : 0;
    pEntry->count++;
    pEntry->chain = pNew;
  }else{
    pHead = 0;
  }
  if( pHead ){
    pNew->next = pHead;
    pNew->prev = pHead->prev;
    if( pHead->prev ){ pHead->prev->next = pNew; }
    else             { pH->first = pNew; }
    pHead->prev = pNew;
  }else{
    pNew->next = pH->first;
    if( pH->first ){ pH->first->prev = pNew; }
    pNew->prev = 0;
    pH->first = pNew;
  }
}


/* Resize the hash table so that it cantains "new_size" buckets.
**
** The hash table might fail to resize if sqlite3_malloc() fails or
** if the new size is the same as the prior size.
** Return TRUE if the resize occurs and false if not.
*/
static int rehash(Hash *pH, unsigned int new_size){
  struct _ht *new_ht;            /* The new hash table */
  HashElem *elem, *next_elem;    /* For looping over existing elements */

#if SQLITE_MALLOC_SOFT_LIMIT>0
  if( new_size*sizeof(struct _ht)>SQLITE_MALLOC_SOFT_LIMIT ){
    new_size = SQLITE_MALLOC_SOFT_LIMIT/sizeof(struct _ht);
  }
  if( new_size==pH->htsize ) return 0;
#endif

  /* The inability to allocates space for a larger hash table is
  ** a performance hit but it is not a fatal error.  So mark the
  ** allocation as a benign.
  */
  sqlite3BeginBenignMalloc();
  new_ht = (struct _ht *)sqlite3Malloc( new_size*sizeof(struct _ht) );
  sqlite3EndBenignMalloc();

  if( new_ht==0 ) return 0;
  sqlite3_free(pH->ht);
  pH->ht = new_ht;
  pH->htsize = new_size = sqlite3MallocSize(new_ht)/sizeof(struct _ht);
  memset(new_ht, 0, new_size*sizeof(struct _ht));
  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
    unsigned int h = strHash(elem->pKey, elem->nKey) % new_size;
    next_elem = elem->next;
    insertElement(pH, &new_ht[h], elem);
  }
  return 1;
}

/* This function (for internal use only) locates an element in an
** hash table that matches the given key.  The hash for this key has
** already been computed and is passed as the 4th parameter.
*/
static HashElem *findElementGivenHash(
  const Hash *pH,     /* The pH to be searched */
  const char *pKey,   /* The key we are searching for */
  int nKey,           /* Bytes in key (not counting zero terminator) */
  unsigned int h      /* The hash for this key. */
){
  HashElem *elem;                /* Used to loop thru the element list */
  int count;                     /* Number of elements left to test */

  if( pH->ht ){
    struct _ht *pEntry = &pH->ht[h];
    elem = pEntry->chain;
    count = pEntry->count;
  }else{
    elem = pH->first;
    count = pH->count;
  }
  while( count-- && ALWAYS(elem) ){
    if( elem->nKey==nKey && sqlite3StrNICmp(elem->pKey,pKey,nKey)==0 ){
      return elem;
    }
    elem = elem->next;
  }
  return 0;
}

/* Remove a single entry from the hash table given a pointer to that
** element and a hash on the element's key.
*/
static void removeElementGivenHash(
  Hash *pH,         /* The pH containing "elem" */
  HashElem* elem,   /* The element to be removed from the pH */
  unsigned int h    /* Hash value for the element */
){
  struct _ht *pEntry;
  if( elem->prev ){
    elem->prev->next = elem->next;
  }else{
    pH->first = elem->next;
  }
  if( elem->next ){
    elem->next->prev = elem->prev;
  }
  if( pH->ht ){
    pEntry = &pH->ht[h];
    if( pEntry->chain==elem ){
      pEntry->chain = elem->next;
    }
    pEntry->count--;
    assert( pEntry->count>=0 );
  }
  sqlite3_free( elem );
  pH->count--;
  if( pH->count<=0 ){
    assert( pH->first==0 );
    assert( pH->count==0 );
    sqlite3HashClear(pH);
  }
}

/* Attempt to locate an element of the hash table pH with a key
** that matches pKey,nKey.  Return the data for this element if it is
** found, or NULL if there is no match.
*/
SQLITE_PRIVATE void *sqlite3HashFind(const Hash *pH, const char *pKey, int nKey){
  HashElem *elem;    /* The element that matches key */
  unsigned int h;    /* A hash on key */

  assert( pH!=0 );
  assert( pKey!=0 );
  assert( nKey>=0 );
  if( pH->ht ){
    h = strHash(pKey, nKey) % pH->htsize;
  }else{
    h = 0;
  }
  elem = findElementGivenHash(pH, pKey, nKey, h);
  return elem ? elem->data : 0;
}

/* Insert an element into the hash table pH.  The key is pKey,nKey
** and the data is "data".
**
** If no element exists with a matching key, then a new
** element is created and NULL is returned.
**
** If another element already exists with the same key, then the
** new data replaces the old data and the old data is returned.
** The key is not copied in this instance.  If a malloc fails, then
** the new data is returned and the hash table is unchanged.
**
** If the "data" parameter to this function is NULL, then the
** element corresponding to "key" is removed from the hash table.
*/
SQLITE_PRIVATE void *sqlite3HashInsert(Hash *pH, const char *pKey, int nKey, void *data){
  unsigned int h;       /* the hash of the key modulo hash table size */
  HashElem *elem;       /* Used to loop thru the element list */
  HashElem *new_elem;   /* New element added to the pH */

  assert( pH!=0 );
  assert( pKey!=0 );
  assert( nKey>=0 );
  if( pH->htsize ){
    h = strHash(pKey, nKey) % pH->htsize;
  }else{
    h = 0;
  }
  elem = findElementGivenHash(pH,pKey,nKey,h);
  if( elem ){
    void *old_data = elem->data;
    if( data==0 ){
      removeElementGivenHash(pH,elem,h);
    }else{
      elem->data = data;
      elem->pKey = pKey;
      assert(nKey==elem->nKey);
    }
    return old_data;
  }
  if( data==0 ) return 0;
  new_elem = (HashElem*)sqlite3Malloc( sizeof(HashElem) );
  if( new_elem==0 ) return data;
  new_elem->pKey = pKey;
  new_elem->nKey = nKey;
  new_elem->data = data;
  pH->count++;
  if( pH->count>=10 && pH->count > 2*pH->htsize ){
    if( rehash(pH, pH->count*2) ){
      assert( pH->htsize>0 );
      h = strHash(pKey, nKey) % pH->htsize;
    }
  }
  if( pH->ht ){
    insertElement(pH, &pH->ht[h], new_elem);
  }else{
    insertElement(pH, 0, new_elem);
  }
  return 0;
}

/************** End of hash.c ************************************************/
/************** Begin file opcodes.c *****************************************/
/* Automatically generated.  Do not edit */
/* See the mkopcodec.awk script for details. */
#if !defined(SQLITE_OMIT_EXPLAIN) || !defined(NDEBUG) || defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
SQLITE_PRIVATE const char *sqlite3OpcodeName(int i){
 static const char *const azName[] = { "?",
     /*   1 */ "Goto",
     /*   2 */ "Gosub",
     /*   3 */ "Return",
     /*   4 */ "Yield",
     /*   5 */ "HaltIfNull",
     /*   6 */ "Halt",
     /*   7 */ "Integer",
     /*   8 */ "Int64",
     /*   9 */ "String",
     /*  10 */ "Null",
     /*  11 */ "Blob",
     /*  12 */ "Variable",
     /*  13 */ "Move",
     /*  14 */ "Copy",
     /*  15 */ "SCopy",
     /*  16 */ "ResultRow",
     /*  17 */ "CollSeq",
     /*  18 */ "Function",
     /*  19 */ "Not",
     /*  20 */ "AddImm",
     /*  21 */ "MustBeInt",
     /*  22 */ "RealAffinity",
     /*  23 */ "Permutation",
     /*  24 */ "Compare",
     /*  25 */ "Jump",
     /*  26 */ "If",
     /*  27 */ "IfNot",
     /*  28 */ "Column",
     /*  29 */ "Affinity",
     /*  30 */ "MakeRecord",
     /*  31 */ "Count",
     /*  32 */ "Savepoint",
     /*  33 */ "AutoCommit",
     /*  34 */ "Transaction",
     /*  35 */ "ReadCookie",
     /*  36 */ "SetCookie",
     /*  37 */ "VerifyCookie",
     /*  38 */ "OpenRead",
     /*  39 */ "OpenWrite",
     /*  40 */ "OpenEphemeral",
     /*  41 */ "OpenPseudo",
     /*  42 */ "Close",
     /*  43 */ "SeekLt",
     /*  44 */ "SeekLe",
     /*  45 */ "SeekGe",
     /*  46 */ "SeekGt",
     /*  47 */ "Seek",
     /*  48 */ "NotFound",
     /*  49 */ "Found",
     /*  50 */ "IsUnique",
     /*  51 */ "NotExists",
     /*  52 */ "Sequence",
     /*  53 */ "NewRowid",
     /*  54 */ "Insert",
     /*  55 */ "InsertInt",
     /*  56 */ "Delete",
     /*  57 */ "ResetCount",
     /*  58 */ "RowKey",
     /*  59 */ "RowData",
     /*  60 */ "Rowid",
     /*  61 */ "NullRow",
     /*  62 */ "Last",
     /*  63 */ "Sort",
     /*  64 */ "Rewind",
     /*  65 */ "Prev",
     /*  66 */ "Next",
     /*  67 */ "IdxInsert",
     /*  68 */ "Or",
     /*  69 */ "And",
     /*  70 */ "IdxDelete",
     /*  71 */ "IdxRowid",
     /*  72 */ "IdxLT",
     /*  73 */ "IsNull",
     /*  74 */ "NotNull",
     /*  75 */ "Ne",
     /*  76 */ "Eq",
     /*  77 */ "Gt",
     /*  78 */ "Le",
     /*  79 */ "Lt",
     /*  80 */ "Ge",
     /*  81 */ "IdxGE",
     /*  82 */ "BitAnd",
     /*  83 */ "BitOr",
     /*  84 */ "ShiftLeft",
     /*  85 */ "ShiftRight",
     /*  86 */ "Add",
     /*  87 */ "Subtract",
     /*  88 */ "Multiply",
     /*  89 */ "Divide",
     /*  90 */ "Remainder",
     /*  91 */ "Concat",
     /*  92 */ "Destroy",
     /*  93 */ "BitNot",
     /*  94 */ "String8",
     /*  95 */ "Clear",
     /*  96 */ "CreateIndex",
     /*  97 */ "CreateTable",
     /*  98 */ "ParseSchema",
     /*  99 */ "LoadAnalysis",
     /* 100 */ "DropTable",
     /* 101 */ "DropIndex",
     /* 102 */ "DropTrigger",
     /* 103 */ "IntegrityCk",
     /* 104 */ "RowSetAdd",
     /* 105 */ "RowSetRead",
     /* 106 */ "RowSetTest",
     /* 107 */ "Program",
     /* 108 */ "Param",
     /* 109 */ "FkCounter",
     /* 110 */ "FkIfZero",
     /* 111 */ "MemMax",
     /* 112 */ "IfPos",
     /* 113 */ "IfNeg",
     /* 114 */ "IfZero",
     /* 115 */ "AggStep",
     /* 116 */ "AggFinal",
     /* 117 */ "Vacuum",
     /* 118 */ "IncrVacuum",
     /* 119 */ "Expire",
     /* 120 */ "TableLock",
     /* 121 */ "VBegin",
     /* 122 */ "VCreate",
     /* 123 */ "VDestroy",
     /* 124 */ "VOpen",
     /* 125 */ "VFilter",
     /* 126 */ "VColumn",
     /* 127 */ "VNext",
     /* 128 */ "VRename",
     /* 129 */ "VUpdate",
     /* 130 */ "Real",
     /* 131 */ "Pagecount",
     /* 132 */ "Trace",
     /* 133 */ "Noop",
     /* 134 */ "Explain",
     /* 135 */ "NotUsed_135",
     /* 136 */ "NotUsed_136",
     /* 137 */ "NotUsed_137",
     /* 138 */ "NotUsed_138",
     /* 139 */ "NotUsed_139",
     /* 140 */ "NotUsed_140",
     /* 141 */ "ToText",
     /* 142 */ "ToBlob",
     /* 143 */ "ToNumeric",
     /* 144 */ "ToInt",
     /* 145 */ "ToReal",
  };
  return azName[i];
}
#endif

/************** End of opcodes.c *********************************************/
/************** Begin file os_os2.c ******************************************/
/*
** 2006 Feb 14
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to OS/2.
*/


#if SQLITE_OS_OS2

/*
** A Note About Memory Allocation:
**
** This driver uses malloc()/free() directly rather than going through
** the SQLite-wrappers sqlite3_malloc()/sqlite3_free().  Those wrappers
** are designed for use on embedded systems where memory is scarce and
** malloc failures happen frequently.  OS/2 does not typically run on
** embedded systems, and when it does the developers normally have bigger
** problems to worry about than running out of memory.  So there is not
** a compelling need to use the wrappers.
**
** But there is a good reason to not use the wrappers.  If we use the
** wrappers then we will get simulated malloc() failures within this
** driver.  And that causes all kinds of problems for our tests.  We
** could enhance SQLite to deal with simulated malloc failures within
** the OS driver, but the code to deal with those failure would not
** be exercised on Linux (which does not need to malloc() in the driver)
** and so we would have difficulty writing coverage tests for that
** code.  Better to leave the code out, we think.
**
** The point of this discussion is as follows:  When creating a new
** OS layer for an embedded system, if you use this file as an example,
** avoid the use of malloc()/free().  Those routines work ok on OS/2
** desktops but not so well in embedded systems.
*/

/*
** Macros used to determine whether or not to use threads.
*/
#if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE
# define SQLITE_OS2_THREADS 1
#endif

/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of os_os2.c ****************/
/************** Begin file os_common.h ***************************************/
/*
** 2004 May 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains macros and a little bit of code that is common to
** all of the platform-specific files (os_*.c) and is #included into those
** files.
**
** This file should be #included by the os_*.c files only.  It is not a
** general purpose header file.
*/
#ifndef _OS_COMMON_H_
#define _OS_COMMON_H_

/*
** At least two bugs have slipped in because we changed the MEMORY_DEBUG
** macro to SQLITE_DEBUG and some older makefiles have not yet made the
** switch.  The following code should catch this problem at compile-time.
*/
#ifdef MEMORY_DEBUG
# error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
#endif

#ifdef SQLITE_DEBUG
SQLITE_PRIVATE int sqlite3OSTrace = 0;
#define OSTRACE1(X)         if( sqlite3OSTrace ) sqlite3DebugPrintf(X)
#define OSTRACE2(X,Y)       if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y)
#define OSTRACE3(X,Y,Z)     if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y,Z)
#define OSTRACE4(X,Y,Z,A)   if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y,Z,A)
#define OSTRACE5(X,Y,Z,A,B) if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y,Z,A,B)
#define OSTRACE6(X,Y,Z,A,B,C) \
    if(sqlite3OSTrace) sqlite3DebugPrintf(X,Y,Z,A,B,C)
#define OSTRACE7(X,Y,Z,A,B,C,D) \
    if(sqlite3OSTrace) sqlite3DebugPrintf(X,Y,Z,A,B,C,D)
#else
#define OSTRACE1(X)
#define OSTRACE2(X,Y)
#define OSTRACE3(X,Y,Z)
#define OSTRACE4(X,Y,Z,A)
#define OSTRACE5(X,Y,Z,A,B)
#define OSTRACE6(X,Y,Z,A,B,C)
#define OSTRACE7(X,Y,Z,A,B,C,D)
#endif

/*
** Macros for performance tracing.  Normally turned off.  Only works
** on i486 hardware.
*/
#ifdef SQLITE_PERFORMANCE_TRACE

/*
** hwtime.h contains inline assembler code for implementing
** high-performance timing routines.
*/
/************** Include hwtime.h in the middle of os_common.h ****************/
/************** Begin file hwtime.h ******************************************/
/*
** 2008 May 27
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains inline asm code for retrieving "high-performance"
** counters for x86 class CPUs.
*/
#ifndef _HWTIME_H_
#define _HWTIME_H_

/*
** The following routine only works on pentium-class (or newer) processors.
** It uses the RDTSC opcode to read the cycle count value out of the
** processor and returns that value.  This can be used for high-res
** profiling.
*/
#if (defined(__GNUC__) || defined(_MSC_VER)) && \
      (defined(i386) || defined(__i386__) || defined(_M_IX86))

  #if defined(__GNUC__)

  __inline__ sqlite_uint64 sqlite3Hwtime(void){
     unsigned int lo, hi;
     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
     return (sqlite_uint64)hi << 32 | lo;
  }

  #elif defined(_MSC_VER)

  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
     __asm {
        rdtsc
        ret       ; return value at EDX:EAX
     }
  }

  #endif

#elif (defined(__GNUC__) && defined(__x86_64__))

  __inline__ sqlite_uint64 sqlite3Hwtime(void){
      unsigned long val;
      __asm__ __volatile__ ("rdtsc" : "=A" (val));
      return val;
  }

#elif (defined(__GNUC__) && defined(__ppc__))

  __inline__ sqlite_uint64 sqlite3Hwtime(void){
      unsigned long long retval;
      unsigned long junk;
      __asm__ __volatile__ ("\n\
          1:      mftbu   %1\n\
                  mftb    %L0\n\
                  mftbu   %0\n\
                  cmpw    %0,%1\n\
                  bne     1b"
                  : "=r" (retval), "=r" (junk));
      return retval;
  }

#else

  #error Need implementation of sqlite3Hwtime() for your platform.

  /*
  ** To compile without implementing sqlite3Hwtime() for your platform,
  ** you can remove the above #error and use the following
  ** stub function.  You will lose timing support for many
  ** of the debugging and testing utilities, but it should at
  ** least compile and run.
  */
SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }

#endif

#endif /* !defined(_HWTIME_H_) */

/************** End of hwtime.h **********************************************/
/************** Continuing where we left off in os_common.h ******************/

static sqlite_uint64 g_start;
static sqlite_uint64 g_elapsed;
#define TIMER_START       g_start=sqlite3Hwtime()
#define TIMER_END         g_elapsed=sqlite3Hwtime()-g_start
#define TIMER_ELAPSED     g_elapsed
#else
#define TIMER_START
#define TIMER_END
#define TIMER_ELAPSED     ((sqlite_uint64)0)
#endif

/*
** If we compile with the SQLITE_TEST macro set, then the following block
** of code will give us the ability to simulate a disk I/O error.  This
** is used for testing the I/O recovery logic.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_io_error_hit = 0;            /* Total number of I/O Errors */
SQLITE_API int sqlite3_io_error_hardhit = 0;        /* Number of non-benign errors */
SQLITE_API int sqlite3_io_error_pending = 0;        /* Count down to first I/O error */
SQLITE_API int sqlite3_io_error_persist = 0;        /* True if I/O errors persist */
SQLITE_API int sqlite3_io_error_benign = 0;         /* True if errors are benign */
SQLITE_API int sqlite3_diskfull_pending = 0;
SQLITE_API int sqlite3_diskfull = 0;
#define SimulateIOErrorBenign(X) sqlite3_io_error_benign=(X)
#define SimulateIOError(CODE)  \
  if( (sqlite3_io_error_persist && sqlite3_io_error_hit) \
       || sqlite3_io_error_pending-- == 1 )  \
              { local_ioerr(); CODE; }
static void local_ioerr(){
  IOTRACE(("IOERR\n"));
  sqlite3_io_error_hit++;
  if( !sqlite3_io_error_benign ) sqlite3_io_error_hardhit++;
}
#define SimulateDiskfullError(CODE) \
   if( sqlite3_diskfull_pending ){ \
     if( sqlite3_diskfull_pending == 1 ){ \
       local_ioerr(); \
       sqlite3_diskfull = 1; \
       sqlite3_io_error_hit = 1; \
       CODE; \
     }else{ \
       sqlite3_diskfull_pending--; \
     } \
   }
#else
#define SimulateIOErrorBenign(X)
#define SimulateIOError(A)
#define SimulateDiskfullError(A)
#endif

/*
** When testing, keep a count of the number of open files.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_open_file_count = 0;
#define OpenCounter(X)  sqlite3_open_file_count+=(X)
#else
#define OpenCounter(X)
#endif

#endif /* !defined(_OS_COMMON_H_) */

/************** End of os_common.h *******************************************/
/************** Continuing where we left off in os_os2.c *********************/

/*
** The os2File structure is subclass of sqlite3_file specific for the OS/2
** protability layer.
*/
typedef struct os2File os2File;
struct os2File {
  const sqlite3_io_methods *pMethod;  /* Always the first entry */
  HFILE h;                  /* Handle for accessing the file */
  char* pathToDel;          /* Name of file to delete on close, NULL if not */
  unsigned char locktype;   /* Type of lock currently held on this file */
};

#define LOCK_TIMEOUT 10L /* the default locking timeout */

/*****************************************************************************
** The next group of routines implement the I/O methods specified
** by the sqlite3_io_methods object.
******************************************************************************/

/*
** Close a file.
*/
static int os2Close( sqlite3_file *id ){
  APIRET rc = NO_ERROR;
  os2File *pFile;
  if( id && (pFile = (os2File*)id) != 0 ){
    OSTRACE2( "CLOSE %d\n", pFile->h );
    rc = DosClose( pFile->h );
    pFile->locktype = NO_LOCK;
    if( pFile->pathToDel != NULL ){
      rc = DosForceDelete( (PSZ)pFile->pathToDel );
      free( pFile->pathToDel );
      pFile->pathToDel = NULL;
    }
    id = 0;
    OpenCounter( -1 );
  }

  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int os2Read(
  sqlite3_file *id,               /* File to read from */
  void *pBuf,                     /* Write content into this buffer */
  int amt,                        /* Number of bytes to read */
  sqlite3_int64 offset            /* Begin reading at this offset */
){
  ULONG fileLocation = 0L;
  ULONG got;
  os2File *pFile = (os2File*)id;
  assert( id!=0 );
  SimulateIOError( return SQLITE_IOERR_READ );
  OSTRACE3( "READ %d lock=%d\n", pFile->h, pFile->locktype );
  if( DosSetFilePtr(pFile->h, offset, FILE_BEGIN, &fileLocation) != NO_ERROR ){
    return SQLITE_IOERR;
  }
  if( DosRead( pFile->h, pBuf, amt, &got ) != NO_ERROR ){
    return SQLITE_IOERR_READ;
  }
  if( got == (ULONG)amt )
    return SQLITE_OK;
  else {
    /* Unread portions of the input buffer must be zero-filled */
    memset(&((char*)pBuf)[got], 0, amt-got);
    return SQLITE_IOERR_SHORT_READ;
  }
}

/*
** Write data from a buffer into a file.  Return SQLITE_OK on success
** or some other error code on failure.
*/
static int os2Write(
  sqlite3_file *id,               /* File to write into */
  const void *pBuf,               /* The bytes to be written */
  int amt,                        /* Number of bytes to write */
  sqlite3_int64 offset            /* Offset into the file to begin writing at */
){
  ULONG fileLocation = 0L;
  APIRET rc = NO_ERROR;
  ULONG wrote;
  os2File *pFile = (os2File*)id;
  assert( id!=0 );
  SimulateIOError( return SQLITE_IOERR_WRITE );
  SimulateDiskfullError( return SQLITE_FULL );
  OSTRACE3( "WRITE %d lock=%d\n", pFile->h, pFile->locktype );
  if( DosSetFilePtr(pFile->h, offset, FILE_BEGIN, &fileLocation) != NO_ERROR ){
    return SQLITE_IOERR;
  }
  assert( amt>0 );
  while( amt > 0 &&
         ( rc = DosWrite( pFile->h, (PVOID)pBuf, amt, &wrote ) ) == NO_ERROR &&
         wrote > 0
  ){
    amt -= wrote;
    pBuf = &((char*)pBuf)[wrote];
  }

  return ( rc != NO_ERROR || amt > (int)wrote ) ? SQLITE_FULL : SQLITE_OK;
}

/*
** Truncate an open file to a specified size
*/
static int os2Truncate( sqlite3_file *id, i64 nByte ){
  APIRET rc = NO_ERROR;
  os2File *pFile = (os2File*)id;
  OSTRACE3( "TRUNCATE %d %lld\n", pFile->h, nByte );
  SimulateIOError( return SQLITE_IOERR_TRUNCATE );
  rc = DosSetFileSize( pFile->h, nByte );
  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR_TRUNCATE;
}

#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs.  This is used to test
** that syncs and fullsyncs are occuring at the right times.
*/
SQLITE_API int sqlite3_sync_count = 0;
SQLITE_API int sqlite3_fullsync_count = 0;
#endif

/*
** Make sure all writes to a particular file are committed to disk.
*/
static int os2Sync( sqlite3_file *id, int flags ){
  os2File *pFile = (os2File*)id;
  OSTRACE3( "SYNC %d lock=%d\n", pFile->h, pFile->locktype );
#ifdef SQLITE_TEST
  if( flags & SQLITE_SYNC_FULL){
    sqlite3_fullsync_count++;
  }
  sqlite3_sync_count++;
#endif
  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
  ** no-op
  */
#ifdef SQLITE_NO_SYNC
  UNUSED_PARAMETER(pFile);
  return SQLITE_OK;
#else
  return DosResetBuffer( pFile->h ) == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
#endif
}

/*
** Determine the current size of a file in bytes
*/
static int os2FileSize( sqlite3_file *id, sqlite3_int64 *pSize ){
  APIRET rc = NO_ERROR;
  FILESTATUS3 fsts3FileInfo;
  memset(&fsts3FileInfo, 0, sizeof(fsts3FileInfo));
  assert( id!=0 );
  SimulateIOError( return SQLITE_IOERR_FSTAT );
  rc = DosQueryFileInfo( ((os2File*)id)->h, FIL_STANDARD, &fsts3FileInfo, sizeof(FILESTATUS3) );
  if( rc == NO_ERROR ){
    *pSize = fsts3FileInfo.cbFile;
    return SQLITE_OK;
  }else{
    return SQLITE_IOERR_FSTAT;
  }
}

/*
** Acquire a reader lock.
*/
static int getReadLock( os2File *pFile ){
  FILELOCK  LockArea,
            UnlockArea;
  APIRET res;
  memset(&LockArea, 0, sizeof(LockArea));
  memset(&UnlockArea, 0, sizeof(UnlockArea));
  LockArea.lOffset = SHARED_FIRST;
  LockArea.lRange = SHARED_SIZE;
  UnlockArea.lOffset = 0L;
  UnlockArea.lRange = 0L;
  res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 1L );
  OSTRACE3( "GETREADLOCK %d res=%d\n", pFile->h, res );
  return res;
}

/*
** Undo a readlock
*/
static int unlockReadLock( os2File *id ){
  FILELOCK  LockArea,
            UnlockArea;
  APIRET res;
  memset(&LockArea, 0, sizeof(LockArea));
  memset(&UnlockArea, 0, sizeof(UnlockArea));
  LockArea.lOffset = 0L;
  LockArea.lRange = 0L;
  UnlockArea.lOffset = SHARED_FIRST;
  UnlockArea.lRange = SHARED_SIZE;
  res = DosSetFileLocks( id->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 1L );
  OSTRACE3( "UNLOCK-READLOCK file handle=%d res=%d?\n", id->h, res );
  return res;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
**     (3) PENDING_LOCK
**     (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between.  The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal.  The following chart shows the allowed
** transitions and the inserted intermediate states:
**
**    UNLOCKED -> SHARED
**    SHARED -> RESERVED
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** This routine will only increase a lock.  The os2Unlock() routine
** erases all locks at once and returns us immediately to locking level 0.
** It is not possible to lower the locking level one step at a time.  You
** must go straight to locking level 0.
*/
static int os2Lock( sqlite3_file *id, int locktype ){
  int rc = SQLITE_OK;       /* Return code from subroutines */
  APIRET res = NO_ERROR;    /* Result of an OS/2 lock call */
  int newLocktype;       /* Set pFile->locktype to this value before exiting */
  int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */
  FILELOCK  LockArea,
            UnlockArea;
  os2File *pFile = (os2File*)id;
  memset(&LockArea, 0, sizeof(LockArea));
  memset(&UnlockArea, 0, sizeof(UnlockArea));
  assert( pFile!=0 );
  OSTRACE4( "LOCK %d %d was %d\n", pFile->h, locktype, pFile->locktype );

  /* If there is already a lock of this type or more restrictive on the
  ** os2File, do nothing. Don't use the end_lock: exit path, as
  ** sqlite3_mutex_enter() hasn't been called yet.
  */
  if( pFile->locktype>=locktype ){
    OSTRACE3( "LOCK %d %d ok (already held)\n", pFile->h, locktype );
    return SQLITE_OK;
  }

  /* Make sure the locking sequence is correct
  */
  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
  assert( locktype!=PENDING_LOCK );
  assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );

  /* Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or
  ** a SHARED lock.  If we are acquiring a SHARED lock, the acquisition of
  ** the PENDING_LOCK byte is temporary.
  */
  newLocktype = pFile->locktype;
  if( pFile->locktype==NO_LOCK
      || (locktype==EXCLUSIVE_LOCK && pFile->locktype==RESERVED_LOCK)
  ){
    LockArea.lOffset = PENDING_BYTE;
    LockArea.lRange = 1L;
    UnlockArea.lOffset = 0L;
    UnlockArea.lRange = 0L;

    /* wait longer than LOCK_TIMEOUT here not to have to try multiple times */
    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, 100L, 0L );
    if( res == NO_ERROR ){
      gotPendingLock = 1;
      OSTRACE3( "LOCK %d pending lock boolean set.  res=%d\n", pFile->h, res );
    }
  }

  /* Acquire a shared lock
  */
  if( locktype==SHARED_LOCK && res == NO_ERROR ){
    assert( pFile->locktype==NO_LOCK );
    res = getReadLock(pFile);
    if( res == NO_ERROR ){
      newLocktype = SHARED_LOCK;
    }
    OSTRACE3( "LOCK %d acquire shared lock. res=%d\n", pFile->h, res );
  }

  /* Acquire a RESERVED lock
  */
  if( locktype==RESERVED_LOCK && res == NO_ERROR ){
    assert( pFile->locktype==SHARED_LOCK );
    LockArea.lOffset = RESERVED_BYTE;
    LockArea.lRange = 1L;
    UnlockArea.lOffset = 0L;
    UnlockArea.lRange = 0L;
    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
    if( res == NO_ERROR ){
      newLocktype = RESERVED_LOCK;
    }
    OSTRACE3( "LOCK %d acquire reserved lock. res=%d\n", pFile->h, res );
  }

  /* Acquire a PENDING lock
  */
  if( locktype==EXCLUSIVE_LOCK && res == NO_ERROR ){
    newLocktype = PENDING_LOCK;
    gotPendingLock = 0;
    OSTRACE2( "LOCK %d acquire pending lock. pending lock boolean unset.\n", pFile->h );
  }

  /* Acquire an EXCLUSIVE lock
  */
  if( locktype==EXCLUSIVE_LOCK && res == NO_ERROR ){
    assert( pFile->locktype>=SHARED_LOCK );
    res = unlockReadLock(pFile);
    OSTRACE2( "unreadlock = %d\n", res );
    LockArea.lOffset = SHARED_FIRST;
    LockArea.lRange = SHARED_SIZE;
    UnlockArea.lOffset = 0L;
    UnlockArea.lRange = 0L;
    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
    if( res == NO_ERROR ){
      newLocktype = EXCLUSIVE_LOCK;
    }else{
      OSTRACE2( "OS/2 error-code = %d\n", res );
      getReadLock(pFile);
    }
    OSTRACE3( "LOCK %d acquire exclusive lock.  res=%d\n", pFile->h, res );
  }

  /* If we are holding a PENDING lock that ought to be released, then
  ** release it now.
  */
  if( gotPendingLock && locktype==SHARED_LOCK ){
    int r;
    LockArea.lOffset = 0L;
    LockArea.lRange = 0L;
    UnlockArea.lOffset = PENDING_BYTE;
    UnlockArea.lRange = 1L;
    r = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
    OSTRACE3( "LOCK %d unlocking pending/is shared. r=%d\n", pFile->h, r );
  }

  /* Update the state of the lock has held in the file descriptor then
  ** return the appropriate result code.
  */
  if( res == NO_ERROR ){
    rc = SQLITE_OK;
  }else{
    OSTRACE4( "LOCK FAILED %d trying for %d but got %d\n", pFile->h,
              locktype, newLocktype );
    rc = SQLITE_BUSY;
  }
  pFile->locktype = newLocktype;
  OSTRACE3( "LOCK %d now %d\n", pFile->h, pFile->locktype );
  return rc;
}

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero, otherwise zero.
*/
static int os2CheckReservedLock( sqlite3_file *id, int *pOut ){
  int r = 0;
  os2File *pFile = (os2File*)id;
  assert( pFile!=0 );
  if( pFile->locktype>=RESERVED_LOCK ){
    r = 1;
    OSTRACE3( "TEST WR-LOCK %d %d (local)\n", pFile->h, r );
  }else{
    FILELOCK  LockArea,
              UnlockArea;
    APIRET rc = NO_ERROR;
    memset(&LockArea, 0, sizeof(LockArea));
    memset(&UnlockArea, 0, sizeof(UnlockArea));
    LockArea.lOffset = RESERVED_BYTE;
    LockArea.lRange = 1L;
    UnlockArea.lOffset = 0L;
    UnlockArea.lRange = 0L;
    rc = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
    OSTRACE3( "TEST WR-LOCK %d lock reserved byte rc=%d\n", pFile->h, rc );
    if( rc == NO_ERROR ){
      APIRET rcu = NO_ERROR; /* return code for unlocking */
      LockArea.lOffset = 0L;
      LockArea.lRange = 0L;
      UnlockArea.lOffset = RESERVED_BYTE;
      UnlockArea.lRange = 1L;
      rcu = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
      OSTRACE3( "TEST WR-LOCK %d unlock reserved byte r=%d\n", pFile->h, rcu );
    }
    r = !(rc == NO_ERROR);
    OSTRACE3( "TEST WR-LOCK %d %d (remote)\n", pFile->h, r );
  }
  *pOut = r;
  return SQLITE_OK;
}

/*
** Lower the locking level on file descriptor id to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** It is not possible for this routine to fail if the second argument
** is NO_LOCK.  If the second argument is SHARED_LOCK then this routine
** might return SQLITE_IOERR;
*/
static int os2Unlock( sqlite3_file *id, int locktype ){
  int type;
  os2File *pFile = (os2File*)id;
  APIRET rc = SQLITE_OK;
  APIRET res = NO_ERROR;
  FILELOCK  LockArea,
            UnlockArea;
  memset(&LockArea, 0, sizeof(LockArea));
  memset(&UnlockArea, 0, sizeof(UnlockArea));
  assert( pFile!=0 );
  assert( locktype<=SHARED_LOCK );
  OSTRACE4( "UNLOCK %d to %d was %d\n", pFile->h, locktype, pFile->locktype );
  type = pFile->locktype;
  if( type>=EXCLUSIVE_LOCK ){
    LockArea.lOffset = 0L;
    LockArea.lRange = 0L;
    UnlockArea.lOffset = SHARED_FIRST;
    UnlockArea.lRange = SHARED_SIZE;
    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
    OSTRACE3( "UNLOCK %d exclusive lock res=%d\n", pFile->h, res );
    if( locktype==SHARED_LOCK && getReadLock(pFile) != NO_ERROR ){
      /* This should never happen.  We should always be able to
      ** reacquire the read lock */
      OSTRACE3( "UNLOCK %d to %d getReadLock() failed\n", pFile->h, locktype );
      rc = SQLITE_IOERR_UNLOCK;
    }
  }
  if( type>=RESERVED_LOCK ){
    LockArea.lOffset = 0L;
    LockArea.lRange = 0L;
    UnlockArea.lOffset = RESERVED_BYTE;
    UnlockArea.lRange = 1L;
    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
    OSTRACE3( "UNLOCK %d reserved res=%d\n", pFile->h, res );
  }
  if( locktype==NO_LOCK && type>=SHARED_LOCK ){
    res = unlockReadLock(pFile);
    OSTRACE5( "UNLOCK %d is %d want %d res=%d\n", pFile->h, type, locktype, res );
  }
  if( type>=PENDING_LOCK ){
    LockArea.lOffset = 0L;
    LockArea.lRange = 0L;
    UnlockArea.lOffset = PENDING_BYTE;
    UnlockArea.lRange = 1L;
    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
    OSTRACE3( "UNLOCK %d pending res=%d\n", pFile->h, res );
  }
  pFile->locktype = locktype;
  OSTRACE3( "UNLOCK %d now %d\n", pFile->h, pFile->locktype );
  return rc;
}

/*
** Control and query of the open file handle.
*/
static int os2FileControl(sqlite3_file *id, int op, void *pArg){
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = ((os2File*)id)->locktype;
      OSTRACE3( "FCNTL_LOCKSTATE %d lock=%d\n", ((os2File*)id)->h, ((os2File*)id)->locktype );
      return SQLITE_OK;
    }
  }
  return SQLITE_ERROR;
}

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
** larger for some devices.
**
** SQLite code assumes this function cannot fail. It also assumes that
** if two files are created in the same file-system directory (i.e.
** a database and its journal file) that the sector size will be the
** same for both.
*/
static int os2SectorSize(sqlite3_file *id){
  return SQLITE_DEFAULT_SECTOR_SIZE;
}

/*
** Return a vector of device characteristics.
*/
static int os2DeviceCharacteristics(sqlite3_file *id){
  return 0;
}


/*
** Character set conversion objects used by conversion routines.
*/
static UconvObject ucUtf8 = NULL; /* convert between UTF-8 and UCS-2 */
static UconvObject uclCp = NULL;  /* convert between local codepage and UCS-2 */

/*
** Helper function to initialize the conversion objects from and to UTF-8.
*/
static void initUconvObjects( void ){
  if( UniCreateUconvObject( UTF_8, &ucUtf8 ) != ULS_SUCCESS )
    ucUtf8 = NULL;
  if ( UniCreateUconvObject( (UniChar *)L"@path=yes", &uclCp ) != ULS_SUCCESS )
    uclCp = NULL;
}

/*
** Helper function to free the conversion objects from and to UTF-8.
*/
static void freeUconvObjects( void ){
  if ( ucUtf8 )
    UniFreeUconvObject( ucUtf8 );
  if ( uclCp )
    UniFreeUconvObject( uclCp );
  ucUtf8 = NULL;
  uclCp = NULL;
}

/*
** Helper function to convert UTF-8 filenames to local OS/2 codepage.
** The two-step process: first convert the incoming UTF-8 string
** into UCS-2 and then from UCS-2 to the current codepage.
** The returned char pointer has to be freed.
*/
static char *convertUtf8PathToCp( const char *in ){
  UniChar tempPath[CCHMAXPATH];
  char *out = (char *)calloc( CCHMAXPATH, 1 );

  if( !out )
    return NULL;

  if( !ucUtf8 || !uclCp )
    initUconvObjects();

  /* determine string for the conversion of UTF-8 which is CP1208 */
  if( UniStrToUcs( ucUtf8, tempPath, (char *)in, CCHMAXPATH ) != ULS_SUCCESS )
    return out; /* if conversion fails, return the empty string */

  /* conversion for current codepage which can be used for paths */
  UniStrFromUcs( uclCp, out, tempPath, CCHMAXPATH );

  return out;
}

/*
** Helper function to convert filenames from local codepage to UTF-8.
** The two-step process: first convert the incoming codepage-specific
** string into UCS-2 and then from UCS-2 to the codepage of UTF-8.
** The returned char pointer has to be freed.
**
** This function is non-static to be able to use this in shell.c and
** similar applications that take command line arguments.
*/
char *convertCpPathToUtf8( const char *in ){
  UniChar tempPath[CCHMAXPATH];
  char *out = (char *)calloc( CCHMAXPATH, 1 );

  if( !out )
    return NULL;

  if( !ucUtf8 || !uclCp )
    initUconvObjects();

  /* conversion for current codepage which can be used for paths */
  if( UniStrToUcs( uclCp, tempPath, (char *)in, CCHMAXPATH ) != ULS_SUCCESS )
    return out; /* if conversion fails, return the empty string */

  /* determine string for the conversion of UTF-8 which is CP1208 */
  UniStrFromUcs( ucUtf8, out, tempPath, CCHMAXPATH );

  return out;
}

/*
** This vector defines all the methods that can operate on an
** sqlite3_file for os2.
*/
static const sqlite3_io_methods os2IoMethod = {
  1,                        /* iVersion */
  os2Close,
  os2Read,
  os2Write,
  os2Truncate,
  os2Sync,
  os2FileSize,
  os2Lock,
  os2Unlock,
  os2CheckReservedLock,
  os2FileControl,
  os2SectorSize,
  os2DeviceCharacteristics
};

/***************************************************************************
** Here ends the I/O methods that form the sqlite3_io_methods object.
**
** The next block of code implements the VFS methods.
****************************************************************************/

/*
** Create a temporary file name in zBuf.  zBuf must be big enough to
** hold at pVfs->mxPathname characters.
*/
static int getTempname(int nBuf, char *zBuf ){
  static const unsigned char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i, j;
  char zTempPathBuf[3];
  PSZ zTempPath = (PSZ)&zTempPathBuf;
  if( sqlite3_temp_directory ){
    zTempPath = sqlite3_temp_directory;
  }else{
    if( DosScanEnv( (PSZ)"TEMP", &zTempPath ) ){
      if( DosScanEnv( (PSZ)"TMP", &zTempPath ) ){
        if( DosScanEnv( (PSZ)"TMPDIR", &zTempPath ) ){
           ULONG ulDriveNum = 0, ulDriveMap = 0;
           DosQueryCurrentDisk( &ulDriveNum, &ulDriveMap );
           sprintf( (char*)zTempPath, "%c:", (char)( 'A' + ulDriveNum - 1 ) );
        }
      }
    }
  }
  /* Strip off a trailing slashes or backslashes, otherwise we would get *
   * multiple (back)slashes which causes DosOpen() to fail.              *
   * Trailing spaces are not allowed, either.                            */
  j = sqlite3Strlen30(zTempPath);
  while( j > 0 && ( zTempPath[j-1] == '\\' || zTempPath[j-1] == '/'
                    || zTempPath[j-1] == ' ' ) ){
    j--;
  }
  zTempPath[j] = '\0';
  if( !sqlite3_temp_directory ){
    char *zTempPathUTF = convertCpPathToUtf8( zTempPath );
    sqlite3_snprintf( nBuf-30, zBuf,
                      "%s\\"SQLITE_TEMP_FILE_PREFIX, zTempPathUTF );
    free( zTempPathUTF );
  }else{
    sqlite3_snprintf( nBuf-30, zBuf,
                      "%s\\"SQLITE_TEMP_FILE_PREFIX, zTempPath );
  }
  j = sqlite3Strlen30( zBuf );
  sqlite3_randomness( 20, &zBuf[j] );
  for( i = 0; i < 20; i++, j++ ){
    zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
  }
  zBuf[j] = 0;
  OSTRACE2( "TEMP FILENAME: %s\n", zBuf );
  return SQLITE_OK;
}


/*
** Turn a relative pathname into a full pathname.  Write the full
** pathname into zFull[].  zFull[] will be at least pVfs->mxPathname
** bytes in size.
*/
static int os2FullPathname(
  sqlite3_vfs *pVfs,          /* Pointer to vfs object */
  const char *zRelative,      /* Possibly relative input path */
  int nFull,                  /* Size of output buffer in bytes */
  char *zFull                 /* Output buffer */
){
  char *zRelativeCp = convertUtf8PathToCp( zRelative );
  char zFullCp[CCHMAXPATH] = "\0";
  char *zFullUTF;
  APIRET rc = DosQueryPathInfo( zRelativeCp, FIL_QUERYFULLNAME, zFullCp,
                                CCHMAXPATH );
  free( zRelativeCp );
  zFullUTF = convertCpPathToUtf8( zFullCp );
  sqlite3_snprintf( nFull, zFull, zFullUTF );
  free( zFullUTF );
  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
}


/*
** Open a file.
*/
static int os2Open(
  sqlite3_vfs *pVfs,            /* Not used */
  const char *zName,            /* Name of the file */
  sqlite3_file *id,             /* Write the SQLite file handle here */
  int flags,                    /* Open mode flags */
  int *pOutFlags                /* Status return flags */
){
  HFILE h;
  ULONG ulFileAttribute = FILE_NORMAL;
  ULONG ulOpenFlags = 0;
  ULONG ulOpenMode = 0;
  os2File *pFile = (os2File*)id;
  APIRET rc = NO_ERROR;
  ULONG ulAction;
  char *zNameCp;
  char zTmpname[CCHMAXPATH+1];    /* Buffer to hold name of temp file */

  /* If the second argument to this function is NULL, generate a
  ** temporary file name to use
  */
  if( !zName ){
    int rc = getTempname(CCHMAXPATH+1, zTmpname);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    zName = zTmpname;
  }


  memset( pFile, 0, sizeof(*pFile) );

  OSTRACE2( "OPEN want %d\n", flags );

  if( flags & SQLITE_OPEN_READWRITE ){
    ulOpenMode |= OPEN_ACCESS_READWRITE;
    OSTRACE1( "OPEN read/write\n" );
  }else{
    ulOpenMode |= OPEN_ACCESS_READONLY;
    OSTRACE1( "OPEN read only\n" );
  }

  if( flags & SQLITE_OPEN_CREATE ){
    ulOpenFlags |= OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_CREATE_IF_NEW;
    OSTRACE1( "OPEN open new/create\n" );
  }else{
    ulOpenFlags |= OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_FAIL_IF_NEW;
    OSTRACE1( "OPEN open existing\n" );
  }

  if( flags & SQLITE_OPEN_MAIN_DB ){
    ulOpenMode |= OPEN_SHARE_DENYNONE;
    OSTRACE1( "OPEN share read/write\n" );
  }else{
    ulOpenMode |= OPEN_SHARE_DENYWRITE;
    OSTRACE1( "OPEN share read only\n" );
  }

  if( flags & SQLITE_OPEN_DELETEONCLOSE ){
    char pathUtf8[CCHMAXPATH];
#ifdef NDEBUG /* when debugging we want to make sure it is deleted */
    ulFileAttribute = FILE_HIDDEN;
#endif
    os2FullPathname( pVfs, zName, CCHMAXPATH, pathUtf8 );
    pFile->pathToDel = convertUtf8PathToCp( pathUtf8 );
    OSTRACE1( "OPEN hidden/delete on close file attributes\n" );
  }else{
    pFile->pathToDel = NULL;
    OSTRACE1( "OPEN normal file attribute\n" );
  }

  /* always open in random access mode for possibly better speed */
  ulOpenMode |= OPEN_FLAGS_RANDOM;
  ulOpenMode |= OPEN_FLAGS_FAIL_ON_ERROR;
  ulOpenMode |= OPEN_FLAGS_NOINHERIT;

  zNameCp = convertUtf8PathToCp( zName );
  rc = DosOpen( (PSZ)zNameCp,
                &h,
                &ulAction,
                0L,
                ulFileAttribute,
                ulOpenFlags,
                ulOpenMode,
                (PEAOP2)NULL );
  free( zNameCp );
  if( rc != NO_ERROR ){
    OSTRACE7( "OPEN Invalid handle rc=%d: zName=%s, ulAction=%#lx, ulAttr=%#lx, ulFlags=%#lx, ulMode=%#lx\n",
              rc, zName, ulAction, ulFileAttribute, ulOpenFlags, ulOpenMode );
    if( pFile->pathToDel )
      free( pFile->pathToDel );
    pFile->pathToDel = NULL;
    if( flags & SQLITE_OPEN_READWRITE ){
      OSTRACE2( "OPEN %d Invalid handle\n", ((flags | SQLITE_OPEN_READONLY) & ~SQLITE_OPEN_READWRITE) );
      return os2Open( pVfs, zName, id,
                      ((flags | SQLITE_OPEN_READONLY) & ~SQLITE_OPEN_READWRITE),
                      pOutFlags );
    }else{
      return SQLITE_CANTOPEN;
    }
  }

  if( pOutFlags ){
    *pOutFlags = flags & SQLITE_OPEN_READWRITE ? SQLITE_OPEN_READWRITE : SQLITE_OPEN_READONLY;
  }

  pFile->pMethod = &os2IoMethod;
  pFile->h = h;
  OpenCounter(+1);
  OSTRACE3( "OPEN %d pOutFlags=%d\n", pFile->h, pOutFlags );
  return SQLITE_OK;
}

/*
** Delete the named file.
*/
static int os2Delete(
  sqlite3_vfs *pVfs,                     /* Not used on os2 */
  const char *zFilename,                 /* Name of file to delete */
  int syncDir                            /* Not used on os2 */
){
  APIRET rc = NO_ERROR;
  char *zFilenameCp = convertUtf8PathToCp( zFilename );
  SimulateIOError( return SQLITE_IOERR_DELETE );
  rc = DosDelete( (PSZ)zFilenameCp );
  free( zFilenameCp );
  OSTRACE2( "DELETE \"%s\"\n", zFilename );
  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR_DELETE;
}

/*
** Check the existance and status of a file.
*/
static int os2Access(
  sqlite3_vfs *pVfs,        /* Not used on os2 */
  const char *zFilename,    /* Name of file to check */
  int flags,                /* Type of test to make on this file */
  int *pOut                 /* Write results here */
){
  FILESTATUS3 fsts3ConfigInfo;
  APIRET rc = NO_ERROR;
  char *zFilenameCp = convertUtf8PathToCp( zFilename );

  memset( &fsts3ConfigInfo, 0, sizeof(fsts3ConfigInfo) );
  rc = DosQueryPathInfo( (PSZ)zFilenameCp, FIL_STANDARD,
                         &fsts3ConfigInfo, sizeof(FILESTATUS3) );
  free( zFilenameCp );
  OSTRACE4( "ACCESS fsts3ConfigInfo.attrFile=%d flags=%d rc=%d\n",
            fsts3ConfigInfo.attrFile, flags, rc );
  switch( flags ){
    case SQLITE_ACCESS_READ:
    case SQLITE_ACCESS_EXISTS:
      rc = (rc == NO_ERROR);
      OSTRACE3( "ACCESS %s access of read and exists  rc=%d\n", zFilename, rc );
      break;
    case SQLITE_ACCESS_READWRITE:
      rc = (rc == NO_ERROR) && ( (fsts3ConfigInfo.attrFile & FILE_READONLY) == 0 );
      OSTRACE3( "ACCESS %s access of read/write  rc=%d\n", zFilename, rc );
      break;
    default:
      assert( !"Invalid flags argument" );
  }
  *pOut = rc;
  return SQLITE_OK;
}


#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
static void *os2DlOpen(sqlite3_vfs *pVfs, const char *zFilename){
  UCHAR loadErr[256];
  HMODULE hmod;
  APIRET rc;
  char *zFilenameCp = convertUtf8PathToCp(zFilename);
  rc = DosLoadModule((PSZ)loadErr, sizeof(loadErr), zFilenameCp, &hmod);
  free(zFilenameCp);
  return rc != NO_ERROR ? 0 : (void*)hmod;
}
/*
** A no-op since the error code is returned on the DosLoadModule call.
** os2Dlopen returns zero if DosLoadModule is not successful.
*/
static void os2DlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){
/* no-op */
}
static void *os2DlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol){
  PFN pfn;
  APIRET rc;
  rc = DosQueryProcAddr((HMODULE)pHandle, 0L, zSymbol, &pfn);
  if( rc != NO_ERROR ){
    /* if the symbol itself was not found, search again for the same
     * symbol with an extra underscore, that might be needed depending
     * on the calling convention */
    char _zSymbol[256] = "_";
    strncat(_zSymbol, zSymbol, 255);
    rc = DosQueryProcAddr((HMODULE)pHandle, 0L, _zSymbol, &pfn);
  }
  return rc != NO_ERROR ? 0 : (void*)pfn;
}
static void os2DlClose(sqlite3_vfs *pVfs, void *pHandle){
  DosFreeModule((HMODULE)pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
  #define os2DlOpen 0
  #define os2DlError 0
  #define os2DlSym 0
  #define os2DlClose 0
#endif


/*
** Write up to nBuf bytes of randomness into zBuf.
*/
static int os2Randomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf ){
  int n = 0;
#if defined(SQLITE_TEST)
  n = nBuf;
  memset(zBuf, 0, nBuf);
#else
  int sizeofULong = sizeof(ULONG);
  if( (int)sizeof(DATETIME) <= nBuf - n ){
    DATETIME x;
    DosGetDateTime(&x);
    memcpy(&zBuf[n], &x, sizeof(x));
    n += sizeof(x);
  }

  if( sizeofULong <= nBuf - n ){
    PPIB ppib;
    DosGetInfoBlocks(NULL, &ppib);
    memcpy(&zBuf[n], &ppib->pib_ulpid, sizeofULong);
    n += sizeofULong;
  }

  if( sizeofULong <= nBuf - n ){
    PTIB ptib;
    DosGetInfoBlocks(&ptib, NULL);
    memcpy(&zBuf[n], &ptib->tib_ptib2->tib2_ultid, sizeofULong);
    n += sizeofULong;
  }

  /* if we still haven't filled the buffer yet the following will */
  /* grab everything once instead of making several calls for a single item */
  if( sizeofULong <= nBuf - n ){
    ULONG ulSysInfo[QSV_MAX];
    DosQuerySysInfo(1L, QSV_MAX, ulSysInfo, sizeofULong * QSV_MAX);

    memcpy(&zBuf[n], &ulSysInfo[QSV_MS_COUNT - 1], sizeofULong);
    n += sizeofULong;

    if( sizeofULong <= nBuf - n ){
      memcpy(&zBuf[n], &ulSysInfo[QSV_TIMER_INTERVAL - 1], sizeofULong);
      n += sizeofULong;
    }
    if( sizeofULong <= nBuf - n ){
      memcpy(&zBuf[n], &ulSysInfo[QSV_TIME_LOW - 1], sizeofULong);
      n += sizeofULong;
    }
    if( sizeofULong <= nBuf - n ){
      memcpy(&zBuf[n], &ulSysInfo[QSV_TIME_HIGH - 1], sizeofULong);
      n += sizeofULong;
    }
    if( sizeofULong <= nBuf - n ){
      memcpy(&zBuf[n], &ulSysInfo[QSV_TOTAVAILMEM - 1], sizeofULong);
      n += sizeofULong;
    }
  }
#endif

  return n;
}

/*
** Sleep for a little while.  Return the amount of time slept.
** The argument is the number of microseconds we want to sleep.
** The return value is the number of microseconds of sleep actually
** requested from the underlying operating system, a number which
** might be greater than or equal to the argument, but not less
** than the argument.
*/
static int os2Sleep( sqlite3_vfs *pVfs, int microsec ){
  DosSleep( (microsec/1000) );
  return microsec;
}

/*
** The following variable, if set to a non-zero value, becomes the result
** returned from sqlite3OsCurrentTime().  This is used for testing.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_current_time = 0;
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
int os2CurrentTime( sqlite3_vfs *pVfs, double *prNow ){
  double now;
  SHORT minute; /* needs to be able to cope with negative timezone offset */
  USHORT second, hour,
         day, month, year;
  DATETIME dt;
  DosGetDateTime( &dt );
  second = (USHORT)dt.seconds;
  minute = (SHORT)dt.minutes + dt.timezone;
  hour = (USHORT)dt.hours;
  day = (USHORT)dt.day;
  month = (USHORT)dt.month;
  year = (USHORT)dt.year;

  /* Calculations from http://www.astro.keele.ac.uk/~rno/Astronomy/hjd.html
     http://www.astro.keele.ac.uk/~rno/Astronomy/hjd-0.1.c */
  /* Calculate the Julian days */
  now = day - 32076 +
    1461*(year + 4800 + (month - 14)/12)/4 +
    367*(month - 2 - (month - 14)/12*12)/12 -
    3*((year + 4900 + (month - 14)/12)/100)/4;

  /* Add the fractional hours, mins and seconds */
  now += (hour + 12.0)/24.0;
  now += minute/1440.0;
  now += second/86400.0;
  *prNow = now;
#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
  }
#endif
  return 0;
}

static int os2GetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
  return 0;
}

/*
** Initialize and deinitialize the operating system interface.
*/
SQLITE_API int sqlite3_os_init(void){
  static sqlite3_vfs os2Vfs = {
    1,                 /* iVersion */
    sizeof(os2File),   /* szOsFile */
    CCHMAXPATH,        /* mxPathname */
    0,                 /* pNext */
    "os2",             /* zName */
    0,                 /* pAppData */

    os2Open,           /* xOpen */
    os2Delete,         /* xDelete */
    os2Access,         /* xAccess */
    os2FullPathname,   /* xFullPathname */
    os2DlOpen,         /* xDlOpen */
    os2DlError,        /* xDlError */
    os2DlSym,          /* xDlSym */
    os2DlClose,        /* xDlClose */
    os2Randomness,     /* xRandomness */
    os2Sleep,          /* xSleep */
    os2CurrentTime,    /* xCurrentTime */
    os2GetLastError    /* xGetLastError */
  };
  sqlite3_vfs_register(&os2Vfs, 1);
  initUconvObjects();
  return SQLITE_OK;
}
SQLITE_API int sqlite3_os_end(void){
  freeUconvObjects();
  return SQLITE_OK;
}

#endif /* SQLITE_OS_OS2 */

/************** End of os_os2.c **********************************************/
/************** Begin file os_unix.c *****************************************/
/*
** 2004 May 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains the VFS implementation for unix-like operating systems
** include Linux, MacOSX, *BSD, QNX, VxWorks, AIX, HPUX, and others.
**
** There are actually several different VFS implementations in this file.
** The differences are in the way that file locking is done.  The default
** implementation uses Posix Advisory Locks.  Alternative implementations
** use flock(), dot-files, various proprietary locking schemas, or simply
** skip locking all together.
**
** This source file is organized into divisions where the logic for various
** subfunctions is contained within the appropriate division.  PLEASE
** KEEP THE STRUCTURE OF THIS FILE INTACT.  New code should be placed
** in the correct division and should be clearly labeled.
**
** The layout of divisions is as follows:
**
**   *  General-purpose declarations and utility functions.
**   *  Unique file ID logic used by VxWorks.
**   *  Various locking primitive implementations (all except proxy locking):
**      + for Posix Advisory Locks
**      + for no-op locks
**      + for dot-file locks
**      + for flock() locking
**      + for named semaphore locks (VxWorks only)
**      + for AFP filesystem locks (MacOSX only)
**   *  sqlite3_file methods not associated with locking.
**   *  Definitions of sqlite3_io_methods objects for all locking
**      methods plus "finder" functions for each locking method.
**   *  sqlite3_vfs method implementations.
**   *  Locking primitives for the proxy uber-locking-method. (MacOSX only)
**   *  Definitions of sqlite3_vfs objects for all locking methods
**      plus implementations of sqlite3_os_init() and sqlite3_os_end().
*/
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/*
** There are various methods for file locking used for concurrency
** control:
**
**   1. POSIX locking (the default),
**   2. No locking,
**   3. Dot-file locking,
**   4. flock() locking,
**   5. AFP locking (OSX only),
**   6. Named POSIX semaphores (VXWorks only),
**   7. proxy locking. (OSX only)
**
** Styles 4, 5, and 7 are only available of SQLITE_ENABLE_LOCKING_STYLE
** is defined to 1.  The SQLITE_ENABLE_LOCKING_STYLE also enables automatic
** selection of the appropriate locking style based on the filesystem
** where the database is located.
*/
#if !defined(SQLITE_ENABLE_LOCKING_STYLE)
#  if defined(__APPLE__)
#    define SQLITE_ENABLE_LOCKING_STYLE 1
#  else
#    define SQLITE_ENABLE_LOCKING_STYLE 0
#  endif
#endif

/*
** Define the OS_VXWORKS pre-processor macro to 1 if building on
** vxworks, or 0 otherwise.
*/
#ifndef OS_VXWORKS
#  if defined(__RTP__) || defined(_WRS_KERNEL)
#    define OS_VXWORKS 1
#  else
#    define OS_VXWORKS 0
#  endif
#endif

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks
** large file support, these should be no-ops.
**
** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
** on the compiler command line.  This is necessary if you are compiling
** on a recent machine (ex: RedHat 7.2) but you want your code to work
** on an older machine (ex: RedHat 6.0).  If you compile on RedHat 7.2
** without this option, LFS is enable.  But LFS does not exist in the kernel
** in RedHat 6.0, so the code won't work.  Hence, for maximum binary
** portability you should omit LFS.
**
** The previous paragraph was written in 2005.  (This paragraph is written
** on 2008-11-28.) These days, all Linux kernels support large files, so
** you should probably leave LFS enabled.  But some embedded platforms might
** lack LFS in which case the SQLITE_DISABLE_LFS macro might still be useful.
*/
#ifndef SQLITE_DISABLE_LFS
# define _LARGE_FILE       1
# ifndef _FILE_OFFSET_BITS
#   define _FILE_OFFSET_BITS 64
# endif
# define _LARGEFILE_SOURCE 1
#endif

/*
** standard include files.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/time.h>
#include <errno.h>

#if SQLITE_ENABLE_LOCKING_STYLE
# include <sys/ioctl.h>
# if OS_VXWORKS
#  include <semaphore.h>
#  include <limits.h>
# else
#  include <sys/file.h>
#  include <sys/param.h>
#  include <sys/mount.h>
# endif
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

/*
** If we are to be thread-safe, include the pthreads header and define
** the SQLITE_UNIX_THREADS macro.
*/
#if SQLITE_THREADSAFE
# define SQLITE_UNIX_THREADS 1
#endif

/*
** Default permissions when creating a new file
*/
#ifndef SQLITE_DEFAULT_FILE_PERMISSIONS
# define SQLITE_DEFAULT_FILE_PERMISSIONS 0644
#endif

/*
 ** Default permissions when creating auto proxy dir
 */
#ifndef SQLITE_DEFAULT_PROXYDIR_PERMISSIONS
# define SQLITE_DEFAULT_PROXYDIR_PERMISSIONS 0755
#endif

/*
** Maximum supported path-length.
*/
#define MAX_PATHNAME 512

/*
** Only set the lastErrno if the error code is a real error and not
** a normal expected return code of SQLITE_BUSY or SQLITE_OK
*/
#define IS_LOCK_ERROR(x)  ((x != SQLITE_OK) && (x != SQLITE_BUSY))


/*
** Sometimes, after a file handle is closed by SQLite, the file descriptor
** cannot be closed immediately. In these cases, instances of the following
** structure are used to store the file descriptor while waiting for an
** opportunity to either close or reuse it.
*/
typedef struct UnixUnusedFd UnixUnusedFd;
struct UnixUnusedFd {
  int fd;                   /* File descriptor to close */
  int flags;                /* Flags this file descriptor was opened with */
  UnixUnusedFd *pNext;      /* Next unused file descriptor on same file */
};

/*
** The unixFile structure is subclass of sqlite3_file specific to the unix
** VFS implementations.
*/
typedef struct unixFile unixFile;
struct unixFile {
  sqlite3_io_methods const *pMethod;  /* Always the first entry */
  struct unixOpenCnt *pOpen;       /* Info about all open fd's on this inode */
  struct unixLockInfo *pLock;      /* Info about locks on this inode */
  int h;                           /* The file descriptor */
  int dirfd;                       /* File descriptor for the directory */
  unsigned char locktype;          /* The type of lock held on this fd */
  int lastErrno;                   /* The unix errno from the last I/O error */
  void *lockingContext;            /* Locking style specific state */
  UnixUnusedFd *pUnused;           /* Pre-allocated UnixUnusedFd */
  int fileFlags;                   /* Miscellanous flags */
#if SQLITE_ENABLE_LOCKING_STYLE
  int openFlags;                   /* The flags specified at open() */
#endif
#if SQLITE_THREADSAFE && defined(__linux__)
  pthread_t tid;                   /* The thread that "owns" this unixFile */
#endif
#if OS_VXWORKS
  int isDelete;                    /* Delete on close if true */
  struct vxworksFileId *pId;       /* Unique file ID */
#endif
#ifndef NDEBUG
  /* The next group of variables are used to track whether or not the
  ** transaction counter in bytes 24-27 of database files are updated
  ** whenever any part of the database changes.  An assertion fault will
  ** occur if a file is updated without also updating the transaction
  ** counter.  This test is made to avoid new problems similar to the
  ** one described by ticket #3584.
  */
  unsigned char transCntrChng;   /* True if the transaction counter changed */
  unsigned char dbUpdate;        /* True if any part of database file changed */
  unsigned char inNormalWrite;   /* True if in a normal write operation */
#endif
#ifdef SQLITE_TEST
  /* In test mode, increase the size of this structure a bit so that
  ** it is larger than the struct CrashFile defined in test6.c.
  */
  char aPadding[32];
#endif
};

/*
** The following macros define bits in unixFile.fileFlags
*/
#define SQLITE_WHOLE_FILE_LOCKING  0x0001   /* Use whole-file locking */

/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of os_unix.c ***************/
/************** Begin file os_common.h ***************************************/
/*
** 2004 May 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains macros and a little bit of code that is common to
** all of the platform-specific files (os_*.c) and is #included into those
** files.
**
** This file should be #included by the os_*.c files only.  It is not a
** general purpose header file.
*/
#ifndef _OS_COMMON_H_
#define _OS_COMMON_H_

/*
** At least two bugs have slipped in because we changed the MEMORY_DEBUG
** macro to SQLITE_DEBUG and some older makefiles have not yet made the
** switch.  The following code should catch this problem at compile-time.
*/
#ifdef MEMORY_DEBUG
# error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
#endif

#ifdef SQLITE_DEBUG
SQLITE_PRIVATE int sqlite3OSTrace = 0;
#define OSTRACE1(X)         if( sqlite3OSTrace ) sqlite3DebugPrintf(X)
#define OSTRACE2(X,Y)       if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y)
#define OSTRACE3(X,Y,Z)     if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y,Z)
#define OSTRACE4(X,Y,Z,A)   if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y,Z,A)
#define OSTRACE5(X,Y,Z,A,B) if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y,Z,A,B)
#define OSTRACE6(X,Y,Z,A,B,C) \
    if(sqlite3OSTrace) sqlite3DebugPrintf(X,Y,Z,A,B,C)
#define OSTRACE7(X,Y,Z,A,B,C,D) \
    if(sqlite3OSTrace) sqlite3DebugPrintf(X,Y,Z,A,B,C,D)
#else
#define OSTRACE1(X)
#define OSTRACE2(X,Y)
#define OSTRACE3(X,Y,Z)
#define OSTRACE4(X,Y,Z,A)
#define OSTRACE5(X,Y,Z,A,B)
#define OSTRACE6(X,Y,Z,A,B,C)
#define OSTRACE7(X,Y,Z,A,B,C,D)
#endif

/*
** Macros for performance tracing.  Normally turned off.  Only works
** on i486 hardware.
*/
#ifdef SQLITE_PERFORMANCE_TRACE

/*
** hwtime.h contains inline assembler code for implementing
** high-performance timing routines.
*/
/************** Include hwtime.h in the middle of os_common.h ****************/
/************** Begin file hwtime.h ******************************************/
/*
** 2008 May 27
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains inline asm code for retrieving "high-performance"
** counters for x86 class CPUs.
*/
#ifndef _HWTIME_H_
#define _HWTIME_H_

/*
** The following routine only works on pentium-class (or newer) processors.
** It uses the RDTSC opcode to read the cycle count value out of the
** processor and returns that value.  This can be used for high-res
** profiling.
*/
#if (defined(__GNUC__) || defined(_MSC_VER)) && \
      (defined(i386) || defined(__i386__) || defined(_M_IX86))

  #if defined(__GNUC__)

  __inline__ sqlite_uint64 sqlite3Hwtime(void){
     unsigned int lo, hi;
     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
     return (sqlite_uint64)hi << 32 | lo;
  }

  #elif defined(_MSC_VER)

  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
     __asm {
        rdtsc
        ret       ; return value at EDX:EAX
     }
  }

  #endif

#elif (defined(__GNUC__) && defined(__x86_64__))

  __inline__ sqlite_uint64 sqlite3Hwtime(void){
      unsigned long val;
      __asm__ __volatile__ ("rdtsc" : "=A" (val));
      return val;
  }

#elif (defined(__GNUC__) && defined(__ppc__))

  __inline__ sqlite_uint64 sqlite3Hwtime(void){
      unsigned long long retval;
      unsigned long junk;
      __asm__ __volatile__ ("\n\
          1:      mftbu   %1\n\
                  mftb    %L0\n\
                  mftbu   %0\n\
                  cmpw    %0,%1\n\
                  bne     1b"
                  : "=r" (retval), "=r" (junk));
      return retval;
  }

#else

  #error Need implementation of sqlite3Hwtime() for your platform.

  /*
  ** To compile without implementing sqlite3Hwtime() for your platform,
  ** you can remove the above #error and use the following
  ** stub function.  You will lose timing support for many
  ** of the debugging and testing utilities, but it should at
  ** least compile and run.
  */
SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }

#endif

#endif /* !defined(_HWTIME_H_) */

/************** End of hwtime.h **********************************************/
/************** Continuing where we left off in os_common.h ******************/

static sqlite_uint64 g_start;
static sqlite_uint64 g_elapsed;
#define TIMER_START       g_start=sqlite3Hwtime()
#define TIMER_END         g_elapsed=sqlite3Hwtime()-g_start
#define TIMER_ELAPSED     g_elapsed
#else
#define TIMER_START
#define TIMER_END
#define TIMER_ELAPSED     ((sqlite_uint64)0)
#endif

/*
** If we compile with the SQLITE_TEST macro set, then the following block
** of code will give us the ability to simulate a disk I/O error.  This
** is used for testing the I/O recovery logic.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_io_error_hit = 0;            /* Total number of I/O Errors */
SQLITE_API int sqlite3_io_error_hardhit = 0;        /* Number of non-benign errors */
SQLITE_API int sqlite3_io_error_pending = 0;        /* Count down to first I/O error */
SQLITE_API int sqlite3_io_error_persist = 0;        /* True if I/O errors persist */
SQLITE_API int sqlite3_io_error_benign = 0;         /* True if errors are benign */
SQLITE_API int sqlite3_diskfull_pending = 0;
SQLITE_API int sqlite3_diskfull = 0;
#define SimulateIOErrorBenign(X) sqlite3_io_error_benign=(X)
#define SimulateIOError(CODE)  \
  if( (sqlite3_io_error_persist && sqlite3_io_error_hit) \
       || sqlite3_io_error_pending-- == 1 )  \
              { local_ioerr(); CODE; }
static void local_ioerr(){
  IOTRACE(("IOERR\n"));
  sqlite3_io_error_hit++;
  if( !sqlite3_io_error_benign ) sqlite3_io_error_hardhit++;
}
#define SimulateDiskfullError(CODE) \
   if( sqlite3_diskfull_pending ){ \
     if( sqlite3_diskfull_pending == 1 ){ \
       local_ioerr(); \
       sqlite3_diskfull = 1; \
       sqlite3_io_error_hit = 1; \
       CODE; \
     }else{ \
       sqlite3_diskfull_pending--; \
     } \
   }
#else
#define SimulateIOErrorBenign(X)
#define SimulateIOError(A)
#define SimulateDiskfullError(A)
#endif

/*
** When testing, keep a count of the number of open files.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_open_file_count = 0;
#define OpenCounter(X)  sqlite3_open_file_count+=(X)
#else
#define OpenCounter(X)
#endif

#endif /* !defined(_OS_COMMON_H_) */

/************** End of os_common.h *******************************************/
/************** Continuing where we left off in os_unix.c ********************/

/*
** Define various macros that are missing from some systems.
*/
#ifndef O_LARGEFILE
# define O_LARGEFILE 0
#endif
#ifdef SQLITE_DISABLE_LFS
# undef O_LARGEFILE
# define O_LARGEFILE 0
#endif
#ifndef O_NOFOLLOW
# define O_NOFOLLOW 0
#endif
#ifndef O_BINARY
# define O_BINARY 0
#endif

/*
** The DJGPP compiler environment looks mostly like Unix, but it
** lacks the fcntl() system call.  So redefine fcntl() to be something
** that always succeeds.  This means that locking does not occur under
** DJGPP.  But it is DOS - what did you expect?
*/
#ifdef __DJGPP__
# define fcntl(A,B,C) 0
#endif

/*
** The threadid macro resolves to the thread-id or to 0.  Used for
** testing and debugging only.
*/
#if SQLITE_THREADSAFE
#define threadid pthread_self()
#else
#define threadid 0
#endif


/*
** Helper functions to obtain and relinquish the global mutex. The
** global mutex is used to protect the unixOpenCnt, unixLockInfo and
** vxworksFileId objects used by this file, all of which may be
** shared by multiple threads.
**
** Function unixMutexHeld() is used to assert() that the global mutex
** is held when required. This function is only used as part of assert()
** statements. e.g.
**
**   unixEnterMutex()
**     assert( unixMutexHeld() );
**   unixEnterLeave()
*/
static void unixEnterMutex(void){
  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
static void unixLeaveMutex(void){
  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
#ifdef SQLITE_DEBUG
static int unixMutexHeld(void) {
  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
#endif


#ifdef SQLITE_DEBUG
/*
** Helper function for printing out trace information from debugging
** binaries. This returns the string represetation of the supplied
** integer lock-type.
*/
static const char *locktypeName(int locktype){
  switch( locktype ){
    case NO_LOCK: return "NONE";
    case SHARED_LOCK: return "SHARED";
    case RESERVED_LOCK: return "RESERVED";
    case PENDING_LOCK: return "PENDING";
    case EXCLUSIVE_LOCK: return "EXCLUSIVE";
  }
  return "ERROR";
}
#endif

#ifdef SQLITE_LOCK_TRACE
/*
** Print out information about all locking operations.
**
** This routine is used for troubleshooting locks on multithreaded
** platforms.  Enable by compiling with the -DSQLITE_LOCK_TRACE
** command-line option on the compiler.  This code is normally
** turned off.
*/
static int lockTrace(int fd, int op, struct flock *p){
  char *zOpName, *zType;
  int s;
  int savedErrno;
  if( op==F_GETLK ){
    zOpName = "GETLK";
  }else if( op==F_SETLK ){
    zOpName = "SETLK";
  }else{
    s = fcntl(fd, op, p);
    sqlite3DebugPrintf("fcntl unknown %d %d %d\n", fd, op, s);
    return s;
  }
  if( p->l_type==F_RDLCK ){
    zType = "RDLCK";
  }else if( p->l_type==F_WRLCK ){
    zType = "WRLCK";
  }else if( p->l_type==F_UNLCK ){
    zType = "UNLCK";
  }else{
    assert( 0 );
  }
  assert( p->l_whence==SEEK_SET );
  s = fcntl(fd, op, p);
  savedErrno = errno;
  sqlite3DebugPrintf("fcntl %d %d %s %s %d %d %d %d\n",
     threadid, fd, zOpName, zType, (int)p->l_start, (int)p->l_len,
     (int)p->l_pid, s);
  if( s==(-1) && op==F_SETLK && (p->l_type==F_RDLCK || p->l_type==F_WRLCK) ){
    struct flock l2;
    l2 = *p;
    fcntl(fd, F_GETLK, &l2);
    if( l2.l_type==F_RDLCK ){
      zType = "RDLCK";
    }else if( l2.l_type==F_WRLCK ){
      zType = "WRLCK";
    }else if( l2.l_type==F_UNLCK ){
      zType = "UNLCK";
    }else{
      assert( 0 );
    }
    sqlite3DebugPrintf("fcntl-failure-reason: %s %d %d %d\n",
       zType, (int)l2.l_start, (int)l2.l_len, (int)l2.l_pid);
  }
  errno = savedErrno;
  return s;
}
#define fcntl lockTrace
#endif /* SQLITE_LOCK_TRACE */



/*
** This routine translates a standard POSIX errno code into something
** useful to the clients of the sqlite3 functions.  Specifically, it is
** intended to translate a variety of "try again" errors into SQLITE_BUSY
** and a variety of "please close the file descriptor NOW" errors into
** SQLITE_IOERR
**
** Errors during initialization of locks, or file system support for locks,
** should handle ENOLCK, ENOTSUP, EOPNOTSUPP separately.
*/
static int sqliteErrorFromPosixError(int posixError, int sqliteIOErr) {
  switch (posixError) {
  case 0:
    return SQLITE_OK;

  case EAGAIN:
  case ETIMEDOUT:
  case EBUSY:
  case EINTR:
  case ENOLCK:
    /* random NFS retry error, unless during file system support
     * introspection, in which it actually means what it says */
    return SQLITE_BUSY;

  case EACCES:
    /* EACCES is like EAGAIN during locking operations, but not any other time*/
    if( (sqliteIOErr == SQLITE_IOERR_LOCK) ||
	(sqliteIOErr == SQLITE_IOERR_UNLOCK) ||
	(sqliteIOErr == SQLITE_IOERR_RDLOCK) ||
	(sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) ){
      return SQLITE_BUSY;
    }
    /* else fall through */
  case EPERM:
    return SQLITE_PERM;

  case EDEADLK:
    return SQLITE_IOERR_BLOCKED;

#if EOPNOTSUPP!=ENOTSUP
  case EOPNOTSUPP:
    /* something went terribly awry, unless during file system support
     * introspection, in which it actually means what it says */
#endif
#ifdef ENOTSUP
  case ENOTSUP:
    /* invalid fd, unless during file system support introspection, in which
     * it actually means what it says */
#endif
  case EIO:
  case EBADF:
  case EINVAL:
  case ENOTCONN:
  case ENODEV:
  case ENXIO:
  case ENOENT:
  case ESTALE:
  case ENOSYS:
    /* these should force the client to close the file and reconnect */

  default:
    return sqliteIOErr;
  }
}



/******************************************************************************
****************** Begin Unique File ID Utility Used By VxWorks ***************
**
** On most versions of unix, we can get a unique ID for a file by concatenating
** the device number and the inode number.  But this does not work on VxWorks.
** On VxWorks, a unique file id must be based on the canonical filename.
**
** A pointer to an instance of the following structure can be used as a
** unique file ID in VxWorks.  Each instance of this structure contains
** a copy of the canonical filename.  There is also a reference count.
** The structure is reclaimed when the number of pointers to it drops to
** zero.
**
** There are never very many files open at one time and lookups are not
** a performance-critical path, so it is sufficient to put these
** structures on a linked list.
*/
struct vxworksFileId {
  struct vxworksFileId *pNext;  /* Next in a list of them all */
  int nRef;                     /* Number of references to this one */
  int nName;                    /* Length of the zCanonicalName[] string */
  char *zCanonicalName;         /* Canonical filename */
};

#if OS_VXWORKS
/*
** All unique filenames are held on a linked list headed by this
** variable:
*/
static struct vxworksFileId *vxworksFileList = 0;

/*
** Simplify a filename into its canonical form
** by making the following changes:
**
**  * removing any trailing and duplicate /
**  * convert /./ into just /
**  * convert /A/../ where A is any simple name into just /
**
** Changes are made in-place.  Return the new name length.
**
** The original filename is in z[0..n-1].  Return the number of
** characters in the simplified name.
*/
static int vxworksSimplifyName(char *z, int n){
  int i, j;
  while( n>1 && z[n-1]=='/' ){ n--; }
  for(i=j=0; i<n; i++){
    if( z[i]=='/' ){
      if( z[i+1]=='/' ) continue;
      if( z[i+1]=='.' && i+2<n && z[i+2]=='/' ){
        i += 1;
        continue;
      }
      if( z[i+1]=='.' && i+3<n && z[i+2]=='.' && z[i+3]=='/' ){
        while( j>0 && z[j-1]!='/' ){ j--; }
        if( j>0 ){ j--; }
        i += 2;
        continue;
      }
    }
    z[j++] = z[i];
  }
  z[j] = 0;
  return j;
}

/*
** Find a unique file ID for the given absolute pathname.  Return
** a pointer to the vxworksFileId object.  This pointer is the unique
** file ID.
**
** The nRef field of the vxworksFileId object is incremented before
** the object is returned.  A new vxworksFileId object is created
** and added to the global list if necessary.
**
** If a memory allocation error occurs, return NULL.
*/
static struct vxworksFileId *vxworksFindFileId(const char *zAbsoluteName){
  struct vxworksFileId *pNew;         /* search key and new file ID */
  struct vxworksFileId *pCandidate;   /* For looping over existing file IDs */
  int n;                              /* Length of zAbsoluteName string */

  assert( zAbsoluteName[0]=='/' );
  n = (int)strlen(zAbsoluteName);
  pNew = sqlite3_malloc( sizeof(*pNew) + (n+1) );
  if( pNew==0 ) return 0;
  pNew->zCanonicalName = (char*)&pNew[1];
  memcpy(pNew->zCanonicalName, zAbsoluteName, n+1);
  n = vxworksSimplifyName(pNew->zCanonicalName, n);

  /* Search for an existing entry that matching the canonical name.
  ** If found, increment the reference count and return a pointer to
  ** the existing file ID.
  */
  unixEnterMutex();
  for(pCandidate=vxworksFileList; pCandidate; pCandidate=pCandidate->pNext){
    if( pCandidate->nName==n
     && memcmp(pCandidate->zCanonicalName, pNew->zCanonicalName, n)==0
    ){
       sqlite3_free(pNew);
       pCandidate->nRef++;
       unixLeaveMutex();
       return pCandidate;
    }
  }

  /* No match was found.  We will make a new file ID */
  pNew->nRef = 1;
  pNew->nName = n;
  pNew->pNext = vxworksFileList;
  vxworksFileList = pNew;
  unixLeaveMutex();
  return pNew;
}

/*
** Decrement the reference count on a vxworksFileId object.  Free
** the object when the reference count reaches zero.
*/
static void vxworksReleaseFileId(struct vxworksFileId *pId){
  unixEnterMutex();
  assert( pId->nRef>0 );
  pId->nRef--;
  if( pId->nRef==0 ){
    struct vxworksFileId **pp;
    for(pp=&vxworksFileList; *pp && *pp!=pId; pp = &((*pp)->pNext)){}
    assert( *pp==pId );
    *pp = pId->pNext;
    sqlite3_free(pId);
  }
  unixLeaveMutex();
}
#endif /* OS_VXWORKS */
/*************** End of Unique File ID Utility Used By VxWorks ****************
******************************************************************************/


/******************************************************************************
*************************** Posix Advisory Locking ****************************
**
** POSIX advisory locks are broken by design.  ANSI STD 1003.1 (1996)
** section 6.5.2.2 lines 483 through 490 specify that when a process
** sets or clears a lock, that operation overrides any prior locks set
** by the same process.  It does not explicitly say so, but this implies
** that it overrides locks set by the same process using a different
** file descriptor.  Consider this test case:
**
**       int fd1 = open("./file1", O_RDWR|O_CREAT, 0644);
**       int fd2 = open("./file2", O_RDWR|O_CREAT, 0644);
**
** Suppose ./file1 and ./file2 are really the same file (because
** one is a hard or symbolic link to the other) then if you set
** an exclusive lock on fd1, then try to get an exclusive lock
** on fd2, it works.  I would have expected the second lock to
** fail since there was already a lock on the file due to fd1.
** But not so.  Since both locks came from the same process, the
** second overrides the first, even though they were on different
** file descriptors opened on different file names.
**
** This means that we cannot use POSIX locks to synchronize file access
** among competing threads of the same process.  POSIX locks will work fine
** to synchronize access for threads in separate processes, but not
** threads within the same process.
**
** To work around the problem, SQLite has to manage file locks internally
** on its own.  Whenever a new database is opened, we have to find the
** specific inode of the database file (the inode is determined by the
** st_dev and st_ino fields of the stat structure that fstat() fills in)
** and check for locks already existing on that inode.  When locks are
** created or removed, we have to look at our own internal record of the
** locks to see if another thread has previously set a lock on that same
** inode.
**
** (Aside: The use of inode numbers as unique IDs does not work on VxWorks.
** For VxWorks, we have to use the alternative unique ID system based on
** canonical filename and implemented in the previous division.)
**
** The sqlite3_file structure for POSIX is no longer just an integer file
** descriptor.  It is now a structure that holds the integer file
** descriptor and a pointer to a structure that describes the internal
** locks on the corresponding inode.  There is one locking structure
** per inode, so if the same inode is opened twice, both unixFile structures
** point to the same locking structure.  The locking structure keeps
** a reference count (so we will know when to delete it) and a "cnt"
** field that tells us its internal lock status.  cnt==0 means the
** file is unlocked.  cnt==-1 means the file has an exclusive lock.
** cnt>0 means there are cnt shared locks on the file.
**
** Any attempt to lock or unlock a file first checks the locking
** structure.  The fcntl() system call is only invoked to set a
** POSIX lock if the internal lock structure transitions between
** a locked and an unlocked state.
**
** But wait:  there are yet more problems with POSIX advisory locks.
**
** If you close a file descriptor that points to a file that has locks,
** all locks on that file that are owned by the current process are
** released.  To work around this problem, each unixFile structure contains
** a pointer to an unixOpenCnt structure.  There is one unixOpenCnt structure
** per open inode, which means that multiple unixFile can point to a single
** unixOpenCnt.  When an attempt is made to close an unixFile, if there are
** other unixFile open on the same inode that are holding locks, the call
** to close() the file descriptor is deferred until all of the locks clear.
** The unixOpenCnt structure keeps a list of file descriptors that need to
** be closed and that list is walked (and cleared) when the last lock
** clears.
**
** Yet another problem:  LinuxThreads do not play well with posix locks.
**
** Many older versions of linux use the LinuxThreads library which is
** not posix compliant.  Under LinuxThreads, a lock created by thread
** A cannot be modified or overridden by a different thread B.
** Only thread A can modify the lock.  Locking behavior is correct
** if the appliation uses the newer Native Posix Thread Library (NPTL)
** on linux - with NPTL a lock created by thread A can override locks
** in thread B.  But there is no way to know at compile-time which
** threading library is being used.  So there is no way to know at
** compile-time whether or not thread A can override locks on thread B.
** We have to do a run-time check to discover the behavior of the
** current process.
**
** On systems where thread A is unable to modify locks created by
** thread B, we have to keep track of which thread created each
** lock.  Hence there is an extra field in the key to the unixLockInfo
** structure to record this information.  And on those systems it
** is illegal to begin a transaction in one thread and finish it
** in another.  For this latter restriction, there is no work-around.
** It is a limitation of LinuxThreads.
*/

/*
** Set or check the unixFile.tid field.  This field is set when an unixFile
** is first opened.  All subsequent uses of the unixFile verify that the
** same thread is operating on the unixFile.  Some operating systems do
** not allow locks to be overridden by other threads and that restriction
** means that sqlite3* database handles cannot be moved from one thread
** to another while locks are held.
**
** Version 3.3.1 (2006-01-15):  unixFile can be moved from one thread to
** another as long as we are running on a system that supports threads
** overriding each others locks (which is now the most common behavior)
** or if no locks are held.  But the unixFile.pLock field needs to be
** recomputed because its key includes the thread-id.  See the
** transferOwnership() function below for additional information
*/
#if SQLITE_THREADSAFE && defined(__linux__)
# define SET_THREADID(X)   (X)->tid = pthread_self()
# define CHECK_THREADID(X) (threadsOverrideEachOthersLocks==0 && \
                            !pthread_equal((X)->tid, pthread_self()))
#else
# define SET_THREADID(X)
# define CHECK_THREADID(X) 0
#endif

/*
** An instance of the following structure serves as the key used
** to locate a particular unixOpenCnt structure given its inode.  This
** is the same as the unixLockKey except that the thread ID is omitted.
*/
struct unixFileId {
  dev_t dev;                  /* Device number */
#if OS_VXWORKS
  struct vxworksFileId *pId;  /* Unique file ID for vxworks. */
#else
  ino_t ino;                  /* Inode number */
#endif
};

/*
** An instance of the following structure serves as the key used
** to locate a particular unixLockInfo structure given its inode.
**
** If threads cannot override each others locks (LinuxThreads), then we
** set the unixLockKey.tid field to the thread ID.  If threads can override
** each others locks (Posix and NPTL) then tid is always set to zero.
** tid is omitted if we compile without threading support or on an OS
** other than linux.
*/
struct unixLockKey {
  struct unixFileId fid;  /* Unique identifier for the file */
#if SQLITE_THREADSAFE && defined(__linux__)
  pthread_t tid;  /* Thread ID of lock owner. Zero if not using LinuxThreads */
#endif
};

/*
** An instance of the following structure is allocated for each open
** inode.  Or, on LinuxThreads, there is one of these structures for
** each inode opened by each thread.
**
** A single inode can have multiple file descriptors, so each unixFile
** structure contains a pointer to an instance of this object and this
** object keeps a count of the number of unixFile pointing to it.
*/
struct unixLockInfo {
  struct unixLockKey lockKey;     /* The lookup key */
  int cnt;                        /* Number of SHARED locks held */
  int locktype;                   /* One of SHARED_LOCK, RESERVED_LOCK etc. */
  int nRef;                       /* Number of pointers to this structure */
  struct unixLockInfo *pNext;     /* List of all unixLockInfo objects */
  struct unixLockInfo *pPrev;     /*    .... doubly linked */
};

/*
** An instance of the following structure is allocated for each open
** inode.  This structure keeps track of the number of locks on that
** inode.  If a close is attempted against an inode that is holding
** locks, the close is deferred until all locks clear by adding the
** file descriptor to be closed to the pending list.
**
** TODO:  Consider changing this so that there is only a single file
** descriptor for each open file, even when it is opened multiple times.
** The close() system call would only occur when the last database
** using the file closes.
*/
struct unixOpenCnt {
  struct unixFileId fileId;   /* The lookup key */
  int nRef;                   /* Number of pointers to this structure */
  int nLock;                  /* Number of outstanding locks */
  UnixUnusedFd *pUnused;      /* Unused file descriptors to close */
#if OS_VXWORKS
  sem_t *pSem;                     /* Named POSIX semaphore */
  char aSemName[MAX_PATHNAME+2];   /* Name of that semaphore */
#endif
  struct unixOpenCnt *pNext, *pPrev;   /* List of all unixOpenCnt objects */
};

/*
** Lists of all unixLockInfo and unixOpenCnt objects.  These used to be hash
** tables.  But the number of objects is rarely more than a dozen and
** never exceeds a few thousand.  And lookup is not on a critical
** path so a simple linked list will suffice.
*/
static struct unixLockInfo *lockList = 0;
static struct unixOpenCnt *openList = 0;

/*
** This variable remembers whether or not threads can override each others
** locks.
**
**    0:  No.  Threads cannot override each others locks.  (LinuxThreads)
**    1:  Yes.  Threads can override each others locks.  (Posix & NLPT)
**   -1:  We don't know yet.
**
** On some systems, we know at compile-time if threads can override each
** others locks.  On those systems, the SQLITE_THREAD_OVERRIDE_LOCK macro
** will be set appropriately.  On other systems, we have to check at
** runtime.  On these latter systems, SQLTIE_THREAD_OVERRIDE_LOCK is
** undefined.
**
** This variable normally has file scope only.  But during testing, we make
** it a global so that the test code can change its value in order to verify
** that the right stuff happens in either case.
*/
#if SQLITE_THREADSAFE && defined(__linux__)
#  ifndef SQLITE_THREAD_OVERRIDE_LOCK
#    define SQLITE_THREAD_OVERRIDE_LOCK -1
#  endif
#  ifdef SQLITE_TEST
int threadsOverrideEachOthersLocks = SQLITE_THREAD_OVERRIDE_LOCK;
#  else
static int threadsOverrideEachOthersLocks = SQLITE_THREAD_OVERRIDE_LOCK;
#  endif
#endif

/*
** This structure holds information passed into individual test
** threads by the testThreadLockingBehavior() routine.
*/
struct threadTestData {
  int fd;                /* File to be locked */
  struct flock lock;     /* The locking operation */
  int result;            /* Result of the locking operation */
};

#if SQLITE_THREADSAFE && defined(__linux__)
/*
** This function is used as the main routine for a thread launched by
** testThreadLockingBehavior(). It tests whether the shared-lock obtained
** by the main thread in testThreadLockingBehavior() conflicts with a
** hypothetical write-lock obtained by this thread on the same file.
**
** The write-lock is not actually acquired, as this is not possible if
** the file is open in read-only mode (see ticket #3472).
*/
static void *threadLockingTest(void *pArg){
  struct threadTestData *pData = (struct threadTestData*)pArg;
  pData->result = fcntl(pData->fd, F_GETLK, &pData->lock);
  return pArg;
}
#endif /* SQLITE_THREADSAFE && defined(__linux__) */


#if SQLITE_THREADSAFE && defined(__linux__)
/*
** This procedure attempts to determine whether or not threads
** can override each others locks then sets the
** threadsOverrideEachOthersLocks variable appropriately.
*/
static void testThreadLockingBehavior(int fd_orig){
  int fd;
  int rc;
  struct threadTestData d;
  struct flock l;
  pthread_t t;

  fd = dup(fd_orig);
  if( fd<0 ) return;
  memset(&l, 0, sizeof(l));
  l.l_type = F_RDLCK;
  l.l_len = 1;
  l.l_start = 0;
  l.l_whence = SEEK_SET;
  rc = fcntl(fd_orig, F_SETLK, &l);
  if( rc!=0 ) return;
  memset(&d, 0, sizeof(d));
  d.fd = fd;
  d.lock = l;
  d.lock.l_type = F_WRLCK;
  if( pthread_create(&t, 0, threadLockingTest, &d)==0 ){
    pthread_join(t, 0);
  }
  close(fd);
  if( d.result!=0 ) return;
  threadsOverrideEachOthersLocks = (d.lock.l_type==F_UNLCK);
}
#endif /* SQLITE_THREADSAFE && defined(__linux__) */

/*
** Release a unixLockInfo structure previously allocated by findLockInfo().
**
** The mutex entered using the unixEnterMutex() function must be held
** when this function is called.
*/
static void releaseLockInfo(struct unixLockInfo *pLock){
  assert( unixMutexHeld() );
  if( pLock ){
    pLock->nRef--;
    if( pLock->nRef==0 ){
      if( pLock->pPrev ){
        assert( pLock->pPrev->pNext==pLock );
        pLock->pPrev->pNext = pLock->pNext;
      }else{
        assert( lockList==pLock );
        lockList = pLock->pNext;
      }
      if( pLock->pNext ){
        assert( pLock->pNext->pPrev==pLock );
        pLock->pNext->pPrev = pLock->pPrev;
      }
      sqlite3_free(pLock);
    }
  }
}

/*
** Release a unixOpenCnt structure previously allocated by findLockInfo().
**
** The mutex entered using the unixEnterMutex() function must be held
** when this function is called.
*/
static void releaseOpenCnt(struct unixOpenCnt *pOpen){
  assert( unixMutexHeld() );
  if( pOpen ){
    pOpen->nRef--;
    if( pOpen->nRef==0 ){
      if( pOpen->pPrev ){
        assert( pOpen->pPrev->pNext==pOpen );
        pOpen->pPrev->pNext = pOpen->pNext;
      }else{
        assert( openList==pOpen );
        openList = pOpen->pNext;
      }
      if( pOpen->pNext ){
        assert( pOpen->pNext->pPrev==pOpen );
        pOpen->pNext->pPrev = pOpen->pPrev;
      }
#if SQLITE_THREADSAFE && defined(__linux__)
      assert( !pOpen->pUnused || threadsOverrideEachOthersLocks==0 );
#endif

      /* If pOpen->pUnused is not null, then memory and file-descriptors
      ** are leaked.
      **
      ** This will only happen if, under Linuxthreads, the user has opened
      ** a transaction in one thread, then attempts to close the database
      ** handle from another thread (without first unlocking the db file).
      ** This is a misuse.  */
      sqlite3_free(pOpen);
    }
  }
}

/*
** Given a file descriptor, locate unixLockInfo and unixOpenCnt structures that
** describes that file descriptor.  Create new ones if necessary.  The
** return values might be uninitialized if an error occurs.
**
** The mutex entered using the unixEnterMutex() function must be held
** when this function is called.
**
** Return an appropriate error code.
*/
static int findLockInfo(
  unixFile *pFile,               /* Unix file with file desc used in the key */
  struct unixLockInfo **ppLock,  /* Return the unixLockInfo structure here */
  struct unixOpenCnt **ppOpen    /* Return the unixOpenCnt structure here */
){
  int rc;                        /* System call return code */
  int fd;                        /* The file descriptor for pFile */
  struct unixLockKey lockKey;    /* Lookup key for the unixLockInfo structure */
  struct unixFileId fileId;      /* Lookup key for the unixOpenCnt struct */
  struct stat statbuf;           /* Low-level file information */
  struct unixLockInfo *pLock = 0;/* Candidate unixLockInfo object */
  struct unixOpenCnt *pOpen;     /* Candidate unixOpenCnt object */

  assert( unixMutexHeld() );

  /* Get low-level information about the file that we can used to
  ** create a unique name for the file.
  */
  fd = pFile->h;
  rc = fstat(fd, &statbuf);
  if( rc!=0 ){
    pFile->lastErrno = errno;
#ifdef EOVERFLOW
    if( pFile->lastErrno==EOVERFLOW ) return SQLITE_NOLFS;
#endif
    return SQLITE_IOERR;
  }

#ifdef __APPLE__
  /* On OS X on an msdos filesystem, the inode number is reported
  ** incorrectly for zero-size files.  See ticket #3260.  To work
  ** around this problem (we consider it a bug in OS X, not SQLite)
  ** we always increase the file size to 1 by writing a single byte
  ** prior to accessing the inode number.  The one byte written is
  ** an ASCII 'S' character which also happens to be the first byte
  ** in the header of every SQLite database.  In this way, if there
  ** is a race condition such that another thread has already populated
  ** the first page of the database, no damage is done.
  */
  if( statbuf.st_size==0 ){
    rc = write(fd, "S", 1);
    if( rc!=1 ){
      return SQLITE_IOERR;
    }
    rc = fstat(fd, &statbuf);
    if( rc!=0 ){
      pFile->lastErrno = errno;
      return SQLITE_IOERR;
    }
  }
#endif

  memset(&lockKey, 0, sizeof(lockKey));
  lockKey.fid.dev = statbuf.st_dev;
#if OS_VXWORKS
  lockKey.fid.pId = pFile->pId;
#else
  lockKey.fid.ino = statbuf.st_ino;
#endif
#if SQLITE_THREADSAFE && defined(__linux__)
  if( threadsOverrideEachOthersLocks<0 ){
    testThreadLockingBehavior(fd);
  }
  lockKey.tid = threadsOverrideEachOthersLocks ? 0 : pthread_self();
#endif
  fileId = lockKey.fid;
  if( ppLock!=0 ){
    pLock = lockList;
    while( pLock && memcmp(&lockKey, &pLock->lockKey, sizeof(lockKey)) ){
      pLock = pLock->pNext;
    }
    if( pLock==0 ){
      pLock = sqlite3_malloc( sizeof(*pLock) );
      if( pLock==0 ){
        rc = SQLITE_NOMEM;
        goto exit_findlockinfo;
      }
      memcpy(&pLock->lockKey,&lockKey,sizeof(lockKey));
      pLock->nRef = 1;
      pLock->cnt = 0;
      pLock->locktype = 0;
      pLock->pNext = lockList;
      pLock->pPrev = 0;
      if( lockList ) lockList->pPrev = pLock;
      lockList = pLock;
    }else{
      pLock->nRef++;
    }
    *ppLock = pLock;
  }
  if( ppOpen!=0 ){
    pOpen = openList;
    while( pOpen && memcmp(&fileId, &pOpen->fileId, sizeof(fileId)) ){
      pOpen = pOpen->pNext;
    }
    if( pOpen==0 ){
      pOpen = sqlite3_malloc( sizeof(*pOpen) );
      if( pOpen==0 ){
        releaseLockInfo(pLock);
        rc = SQLITE_NOMEM;
        goto exit_findlockinfo;
      }
      memset(pOpen, 0, sizeof(*pOpen));
      pOpen->fileId = fileId;
      pOpen->nRef = 1;
      pOpen->pNext = openList;
      if( openList ) openList->pPrev = pOpen;
      openList = pOpen;
    }else{
      pOpen->nRef++;
    }
    *ppOpen = pOpen;
  }

exit_findlockinfo:
  return rc;
}

/*
** If we are currently in a different thread than the thread that the
** unixFile argument belongs to, then transfer ownership of the unixFile
** over to the current thread.
**
** A unixFile is only owned by a thread on systems that use LinuxThreads.
**
** Ownership transfer is only allowed if the unixFile is currently unlocked.
** If the unixFile is locked and an ownership is wrong, then return
** SQLITE_MISUSE.  SQLITE_OK is returned if everything works.
*/
#if SQLITE_THREADSAFE && defined(__linux__)
static int transferOwnership(unixFile *pFile){
  int rc;
  pthread_t hSelf;
  if( threadsOverrideEachOthersLocks ){
    /* Ownership transfers not needed on this system */
    return SQLITE_OK;
  }
  hSelf = pthread_self();
  if( pthread_equal(pFile->tid, hSelf) ){
    /* We are still in the same thread */
    OSTRACE1("No-transfer, same thread\n");
    return SQLITE_OK;
  }
  if( pFile->locktype!=NO_LOCK ){
    /* We cannot change ownership while we are holding a lock! */
    return SQLITE_MISUSE_BKPT;
  }
  OSTRACE4("Transfer ownership of %d from %d to %d\n",
            pFile->h, pFile->tid, hSelf);
  pFile->tid = hSelf;
  if (pFile->pLock != NULL) {
    releaseLockInfo(pFile->pLock);
    rc = findLockInfo(pFile, &pFile->pLock, 0);
    OSTRACE5("LOCK    %d is now %s(%s,%d)\n", pFile->h,
           locktypeName(pFile->locktype),
           locktypeName(pFile->pLock->locktype), pFile->pLock->cnt);
    return rc;
  } else {
    return SQLITE_OK;
  }
}
#else  /* if not SQLITE_THREADSAFE */
  /* On single-threaded builds, ownership transfer is a no-op */
# define transferOwnership(X) SQLITE_OK
#endif /* SQLITE_THREADSAFE */


/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );

  assert( pFile );
  unixEnterMutex(); /* Because pFile->pLock is shared across threads */

  /* Check if a thread in this process holds such a lock */
  if( pFile->pLock->locktype>SHARED_LOCK ){
    reserved = 1;
  }

  /* Otherwise see if some other process holds it.
  */
#ifndef __DJGPP__
  if( !reserved ){
    struct flock lock;
    lock.l_whence = SEEK_SET;
    lock.l_start = RESERVED_BYTE;
    lock.l_len = 1;
    lock.l_type = F_WRLCK;
    if (-1 == fcntl(pFile->h, F_GETLK, &lock)) {
      int tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
      pFile->lastErrno = tErrno;
    } else if( lock.l_type!=F_UNLCK ){
      reserved = 1;
    }
  }
#endif

  unixLeaveMutex();
  OSTRACE4("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved);

  *pResOut = reserved;
  return rc;
}

/*
** Perform a file locking operation on a range of bytes in a file.
** The "op" parameter should be one of F_RDLCK, F_WRLCK, or F_UNLCK.
** Return 0 on success or -1 for failure.  On failure, write the error
** code into *pErrcode.
**
** If the SQLITE_WHOLE_FILE_LOCKING bit is clear, then only lock
** the range of bytes on the locking page between SHARED_FIRST and
** SHARED_SIZE.  If SQLITE_WHOLE_FILE_LOCKING is set, then lock all
** bytes from 0 up to but not including PENDING_BYTE, and all bytes
** that follow SHARED_FIRST.
**
** In other words, of SQLITE_WHOLE_FILE_LOCKING if false (the historical
** default case) then only lock a small range of bytes from SHARED_FIRST
** through SHARED_FIRST+SHARED_SIZE-1.  But if SQLITE_WHOLE_FILE_LOCKING is
** true then lock every byte in the file except for PENDING_BYTE and
** RESERVED_BYTE.
**
** SQLITE_WHOLE_FILE_LOCKING=true overlaps SQLITE_WHOLE_FILE_LOCKING=false
** and so the locking schemes are compatible.  One type of lock will
** effectively exclude the other type.  The reason for using the
** SQLITE_WHOLE_FILE_LOCKING=true is that by indicating the full range
** of bytes to be read or written, we give hints to NFS to help it
** maintain cache coherency.  On the other hand, whole file locking
** is slower, so we don't want to use it except for NFS.
*/
static int rangeLock(unixFile *pFile, int op, int *pErrcode){
  struct flock lock;
  int rc;
  lock.l_type = op;
  lock.l_start = SHARED_FIRST;
  lock.l_whence = SEEK_SET;
  if( (pFile->fileFlags & SQLITE_WHOLE_FILE_LOCKING)==0 ){
    lock.l_len = SHARED_SIZE;
    rc = fcntl(pFile->h, F_SETLK, &lock);
    *pErrcode = errno;
  }else{
    lock.l_len = 0;
    rc = fcntl(pFile->h, F_SETLK, &lock);
    *pErrcode = errno;
    if( NEVER(op==F_UNLCK) || rc!=(-1) ){
      lock.l_start = 0;
      lock.l_len = PENDING_BYTE;
      rc = fcntl(pFile->h, F_SETLK, &lock);
      if( ALWAYS(op!=F_UNLCK) && rc==(-1) ){
        *pErrcode = errno;
        lock.l_type = F_UNLCK;
        lock.l_start = SHARED_FIRST;
        lock.l_len = 0;
        fcntl(pFile->h, F_SETLK, &lock);
      }
    }
  }
  return rc;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
**     (3) PENDING_LOCK
**     (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between.  The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal.  The following chart shows the allowed
** transitions and the inserted intermediate states:
**
**    UNLOCKED -> SHARED
**    SHARED -> RESERVED
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int unixLock(sqlite3_file *id, int locktype){
  /* The following describes the implementation of the various locks and
  ** lock transitions in terms of the POSIX advisory shared and exclusive
  ** lock primitives (called read-locks and write-locks below, to avoid
  ** confusion with SQLite lock names). The algorithms are complicated
  ** slightly in order to be compatible with windows systems simultaneously
  ** accessing the same database file, in case that is ever required.
  **
  ** Symbols defined in os.h indentify the 'pending byte' and the 'reserved
  ** byte', each single bytes at well known offsets, and the 'shared byte
  ** range', a range of 510 bytes at a well known offset.
  **
  ** To obtain a SHARED lock, a read-lock is obtained on the 'pending
  ** byte'.  If this is successful, a random byte from the 'shared byte
  ** range' is read-locked and the lock on the 'pending byte' released.
  **
  ** A process may only obtain a RESERVED lock after it has a SHARED lock.
  ** A RESERVED lock is implemented by grabbing a write-lock on the
  ** 'reserved byte'.
  **
  ** A process may only obtain a PENDING lock after it has obtained a
  ** SHARED lock. A PENDING lock is implemented by obtaining a write-lock
  ** on the 'pending byte'. This ensures that no new SHARED locks can be
  ** obtained, but existing SHARED locks are allowed to persist. A process
  ** does not have to obtain a RESERVED lock on the way to a PENDING lock.
  ** This property is used by the algorithm for rolling back a journal file
  ** after a crash.
  **
  ** An EXCLUSIVE lock, obtained after a PENDING lock is held, is
  ** implemented by obtaining a write-lock on the entire 'shared byte
  ** range'. Since all other locks require a read-lock on one of the bytes
  ** within this range, this ensures that no other locks are held on the
  ** database.
  **
  ** The reason a single byte cannot be used instead of the 'shared byte
  ** range' is that some versions of windows do not support read-locks. By
  ** locking a random byte from a range, concurrent SHARED locks may exist
  ** even if the locking primitive used is always a write-lock.
  */
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  struct unixLockInfo *pLock = pFile->pLock;
  struct flock lock;
  int s = 0;
  int tErrno;

  assert( pFile );
  OSTRACE7("LOCK    %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
      locktypeName(locktype), locktypeName(pFile->locktype),
      locktypeName(pLock->locktype), pLock->cnt , getpid());

  /* If there is already a lock of this type or more restrictive on the
  ** unixFile, do nothing. Don't use the end_lock: exit path, as
  ** unixEnterMutex() hasn't been called yet.
  */
  if( pFile->locktype>=locktype ){
    OSTRACE3("LOCK    %d %s ok (already held) (unix)\n", pFile->h,
            locktypeName(locktype));
    return SQLITE_OK;
  }

  /* Make sure the locking sequence is correct.
  **  (1) We never move from unlocked to anything higher than shared lock.
  **  (2) SQLite never explicitly requests a pendig lock.
  **  (3) A shared lock is always held when a reserve lock is requested.
  */
  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
  assert( locktype!=PENDING_LOCK );
  assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );

  /* This mutex is needed because pFile->pLock is shared across threads
  */
  unixEnterMutex();

  /* Make sure the current thread owns the pFile.
  */
  rc = transferOwnership(pFile);
  if( rc!=SQLITE_OK ){
    unixLeaveMutex();
    return rc;
  }
  pLock = pFile->pLock;

  /* If some thread using this PID has a lock via a different unixFile*
  ** handle that precludes the requested lock, return BUSY.
  */
  if( (pFile->locktype!=pLock->locktype &&
          (pLock->locktype>=PENDING_LOCK || locktype>SHARED_LOCK))
  ){
    rc = SQLITE_BUSY;
    goto end_lock;
  }

  /* If a SHARED lock is requested, and some thread using this PID already
  ** has a SHARED or RESERVED lock, then increment reference counts and
  ** return SQLITE_OK.
  */
  if( locktype==SHARED_LOCK &&
      (pLock->locktype==SHARED_LOCK || pLock->locktype==RESERVED_LOCK) ){
    assert( locktype==SHARED_LOCK );
    assert( pFile->locktype==0 );
    assert( pLock->cnt>0 );
    pFile->locktype = SHARED_LOCK;
    pLock->cnt++;
    pFile->pOpen->nLock++;
    goto end_lock;
  }


  /* A PENDING lock is needed before acquiring a SHARED lock and before
  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
  ** be released.
  */
  lock.l_len = 1L;
  lock.l_whence = SEEK_SET;
  if( locktype==SHARED_LOCK
      || (locktype==EXCLUSIVE_LOCK && pFile->locktype<PENDING_LOCK)
  ){
    lock.l_type = (locktype==SHARED_LOCK?F_RDLCK:F_WRLCK);
    lock.l_start = PENDING_BYTE;
    s = fcntl(pFile->h, F_SETLK, &lock);
    if( s==(-1) ){
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
      goto end_lock;
    }
  }


  /* If control gets to this point, then actually go ahead and make
  ** operating system calls for the specified lock.
  */
  if( locktype==SHARED_LOCK ){
    assert( pLock->cnt==0 );
    assert( pLock->locktype==0 );

    /* Now get the read-lock */
    s = rangeLock(pFile, F_RDLCK, &tErrno);

    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( fcntl(pFile->h, F_SETLK, &lock)!=0 ){
      if( s != -1 ){
        /* This could happen with a network mount */
        tErrno = errno;
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
        goto end_lock;
      }
    }
    if( s==(-1) ){
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }else{
      pFile->locktype = SHARED_LOCK;
      pFile->pOpen->nLock++;
      pLock->cnt = 1;
    }
  }else if( locktype==EXCLUSIVE_LOCK && pLock->cnt>1 ){
    /* We are trying for an exclusive lock but another thread in this
    ** same process is still holding a shared lock. */
    rc = SQLITE_BUSY;
  }else{
    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
    ** assumed that there is a SHARED or greater lock on the file
    ** already.
    */
    assert( 0!=pFile->locktype );
    lock.l_type = F_WRLCK;
    switch( locktype ){
      case RESERVED_LOCK:
        lock.l_start = RESERVED_BYTE;
        s = fcntl(pFile->h, F_SETLK, &lock);
        tErrno = errno;
        break;
      case EXCLUSIVE_LOCK:
        s = rangeLock(pFile, F_WRLCK, &tErrno);
        break;
      default:
        assert(0);
    }
    if( s==(-1) ){
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }
  }


#ifndef NDEBUG
  /* Set up the transaction-counter change checking flags when
  ** transitioning from a SHARED to a RESERVED lock.  The change
  ** from SHARED to RESERVED marks the beginning of a normal
  ** write operation (not a hot journal rollback).
  */
  if( rc==SQLITE_OK
   && pFile->locktype<=SHARED_LOCK
   && locktype==RESERVED_LOCK
  ){
    pFile->transCntrChng = 0;
    pFile->dbUpdate = 0;
    pFile->inNormalWrite = 1;
  }
#endif


  if( rc==SQLITE_OK ){
    pFile->locktype = locktype;
    pLock->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    pFile->locktype = PENDING_LOCK;
    pLock->locktype = PENDING_LOCK;
  }

end_lock:
  unixLeaveMutex();
  OSTRACE4("LOCK    %d %s %s (unix)\n", pFile->h, locktypeName(locktype),
      rc==SQLITE_OK ? "ok" : "failed");
  return rc;
}

/*
** Close all file descriptors accumuated in the unixOpenCnt->pUnused list.
** If all such file descriptors are closed without error, the list is
** cleared and SQLITE_OK returned.
**
** Otherwise, if an error occurs, then successfully closed file descriptor
** entries are removed from the list, and SQLITE_IOERR_CLOSE returned.
** not deleted and SQLITE_IOERR_CLOSE returned.
*/
static int closePendingFds(unixFile *pFile){
  int rc = SQLITE_OK;
  struct unixOpenCnt *pOpen = pFile->pOpen;
  UnixUnusedFd *pError = 0;
  UnixUnusedFd *p;
  UnixUnusedFd *pNext;
  for(p=pOpen->pUnused; p; p=pNext){
    pNext = p->pNext;
    if( close(p->fd) ){
      pFile->lastErrno = errno;
      rc = SQLITE_IOERR_CLOSE;
      p->pNext = pError;
      pError = p;
    }else{
      sqlite3_free(p);
    }
  }
  pOpen->pUnused = pError;
  return rc;
}

/*
** Add the file descriptor used by file handle pFile to the corresponding
** pUnused list.
*/
static void setPendingFd(unixFile *pFile){
  struct unixOpenCnt *pOpen = pFile->pOpen;
  UnixUnusedFd *p = pFile->pUnused;
  p->pNext = pOpen->pUnused;
  pOpen->pUnused = p;
  pFile->h = -1;
  pFile->pUnused = 0;
}

/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int unixUnlock(sqlite3_file *id, int locktype){
  unixFile *pFile = (unixFile*)id; /* The open file */
  struct unixLockInfo *pLock;      /* Structure describing current lock state */
  struct flock lock;               /* Information passed into fcntl() */
  int rc = SQLITE_OK;              /* Return code from this interface */
  int h;                           /* The underlying file descriptor */
  int tErrno;                      /* Error code from system call errors */

  assert( pFile );
  OSTRACE7("UNLOCK  %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, locktype,
      pFile->locktype, pFile->pLock->locktype, pFile->pLock->cnt, getpid());

  assert( locktype<=SHARED_LOCK );
  if( pFile->locktype<=locktype ){
    return SQLITE_OK;
  }
  if( CHECK_THREADID(pFile) ){
    return SQLITE_MISUSE_BKPT;
  }
  unixEnterMutex();
  h = pFile->h;
  pLock = pFile->pLock;
  assert( pLock->cnt!=0 );
  if( pFile->locktype>SHARED_LOCK ){
    assert( pLock->locktype==pFile->locktype );
    SimulateIOErrorBenign(1);
    SimulateIOError( h=(-1) )
    SimulateIOErrorBenign(0);

#ifndef NDEBUG
    /* When reducing a lock such that other processes can start
    ** reading the database file again, make sure that the
    ** transaction counter was updated if any part of the database
    ** file changed.  If the transaction counter is not updated,
    ** other connections to the same file might not realize that
    ** the file has changed and hence might not know to flush their
    ** cache.  The use of a stale cache can lead to database corruption.
    */
    assert( pFile->inNormalWrite==0
         || pFile->dbUpdate==0
         || pFile->transCntrChng==1 );
    pFile->inNormalWrite = 0;
#endif


    if( locktype==SHARED_LOCK ){
      if( rangeLock(pFile, F_RDLCK, &tErrno)==(-1) ){
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
        goto end_unlock;
      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( fcntl(h, F_SETLK, &lock)!=(-1) ){
      pLock->locktype = SHARED_LOCK;
    }else{
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
      goto end_unlock;
    }
  }
  if( locktype==NO_LOCK ){
    struct unixOpenCnt *pOpen;

    /* Decrement the shared lock counter.  Release the lock using an
    ** OS call only when all threads in this same process have released
    ** the lock.
    */
    pLock->cnt--;
    if( pLock->cnt==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      SimulateIOErrorBenign(1);
      SimulateIOError( h=(-1) )
      SimulateIOErrorBenign(0);
      if( fcntl(h, F_SETLK, &lock)!=(-1) ){
        pLock->locktype = NO_LOCK;
      }else{
        tErrno = errno;
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
        pLock->locktype = NO_LOCK;
        pFile->locktype = NO_LOCK;
      }
    }

    /* Decrement the count of locks against this same file.  When the
    ** count reaches zero, close any other file descriptors whose close
    ** was deferred because of outstanding locks.
    */
    pOpen = pFile->pOpen;
    pOpen->nLock--;
    assert( pOpen->nLock>=0 );
    if( pOpen->nLock==0 ){
      int rc2 = closePendingFds(pFile);
      if( rc==SQLITE_OK ){
        rc = rc2;
      }
    }
  }

end_unlock:
  unixLeaveMutex();
  if( rc==SQLITE_OK ) pFile->locktype = locktype;
  return rc;
}

/*
** This function performs the parts of the "close file" operation
** common to all locking schemes. It closes the directory and file
** handles, if they are valid, and sets all fields of the unixFile
** structure to 0.
**
** It is *not* necessary to hold the mutex when this routine is called,
** even on VxWorks.  A mutex will be acquired on VxWorks by the
** vxworksReleaseFileId() routine.
*/
static int closeUnixFile(sqlite3_file *id){
  unixFile *pFile = (unixFile*)id;
  if( pFile ){
    if( pFile->dirfd>=0 ){
      int err = close(pFile->dirfd);
      if( err ){
        pFile->lastErrno = errno;
        return SQLITE_IOERR_DIR_CLOSE;
      }else{
        pFile->dirfd=-1;
      }
    }
    if( pFile->h>=0 ){
      int err = close(pFile->h);
      if( err ){
        pFile->lastErrno = errno;
        return SQLITE_IOERR_CLOSE;
      }
    }
#if OS_VXWORKS
    if( pFile->pId ){
      if( pFile->isDelete ){
        unlink(pFile->pId->zCanonicalName);
      }
      vxworksReleaseFileId(pFile->pId);
      pFile->pId = 0;
    }
#endif
    OSTRACE2("CLOSE   %-3d\n", pFile->h);
    OpenCounter(-1);
    sqlite3_free(pFile->pUnused);
    memset(pFile, 0, sizeof(unixFile));
  }
  return SQLITE_OK;
}

/*
** Close a file.
*/
static int unixClose(sqlite3_file *id){
  int rc = SQLITE_OK;
  if( id ){
    unixFile *pFile = (unixFile *)id;
    unixUnlock(id, NO_LOCK);
    unixEnterMutex();
    if( pFile->pOpen && pFile->pOpen->nLock ){
      /* If there are outstanding locks, do not actually close the file just
      ** yet because that would clear those locks.  Instead, add the file
      ** descriptor to pOpen->pUnused list.  It will be automatically closed
      ** when the last lock is cleared.
      */
      setPendingFd(pFile);
    }
    releaseLockInfo(pFile->pLock);
    releaseOpenCnt(pFile->pOpen);
    rc = closeUnixFile(id);
    unixLeaveMutex();
  }
  return rc;
}

/************** End of the posix advisory lock implementation *****************
******************************************************************************/

/******************************************************************************
****************************** No-op Locking **********************************
**
** Of the various locking implementations available, this is by far the
** simplest:  locking is ignored.  No attempt is made to lock the database
** file for reading or writing.
**
** This locking mode is appropriate for use on read-only databases
** (ex: databases that are burned into CD-ROM, for example.)  It can
** also be used if the application employs some external mechanism to
** prevent simultaneous access of the same database by two or more
** database connections.  But there is a serious risk of database
** corruption if this locking mode is used in situations where multiple
** database connections are accessing the same database file at the same
** time and one or more of those connections are writing.
*/

static int nolockCheckReservedLock(sqlite3_file *NotUsed, int *pResOut){
  UNUSED_PARAMETER(NotUsed);
  *pResOut = 0;
  return SQLITE_OK;
}
static int nolockLock(sqlite3_file *NotUsed, int NotUsed2){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  return SQLITE_OK;
}
static int nolockUnlock(sqlite3_file *NotUsed, int NotUsed2){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  return SQLITE_OK;
}

/*
** Close the file.
*/
static int nolockClose(sqlite3_file *id) {
  return closeUnixFile(id);
}

/******************* End of the no-op lock implementation *********************
******************************************************************************/

/******************************************************************************
************************* Begin dot-file Locking ******************************
**
** The dotfile locking implementation uses the existance of separate lock
** files in order to control access to the database.  This works on just
** about every filesystem imaginable.  But there are serious downsides:
**
**    (1)  There is zero concurrency.  A single reader blocks all other
**         connections from reading or writing the database.
**
**    (2)  An application crash or power loss can leave stale lock files
**         sitting around that need to be cleared manually.
**
** Nevertheless, a dotlock is an appropriate locking mode for use if no
** other locking strategy is available.
**
** Dotfile locking works by creating a file in the same directory as the
** database and with the same name but with a ".lock" extension added.
** The existance of a lock file implies an EXCLUSIVE lock.  All other lock
** types (SHARED, RESERVED, PENDING) are mapped into EXCLUSIVE.
*/

/*
** The file suffix added to the data base filename in order to create the
** lock file.
*/
#define DOTLOCK_SUFFIX ".lock"

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
**
** In dotfile locking, either a lock exists or it does not.  So in this
** variation of CheckReservedLock(), *pResOut is set to true if any lock
** is held on the file and false if the file is unlocked.
*/
static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );

  assert( pFile );

  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    /* Either this connection or some other connection in the same process
    ** holds a lock on the file.  No need to check further. */
    reserved = 1;
  }else{
    /* The lock is held if and only if the lockfile exists */
    const char *zLockFile = (const char*)pFile->lockingContext;
    reserved = access(zLockFile, 0)==0;
  }
  OSTRACE4("TEST WR-LOCK %d %d %d (dotlock)\n", pFile->h, rc, reserved);
  *pResOut = reserved;
  return rc;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
**     (3) PENDING_LOCK
**     (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between.  The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal.  The following chart shows the allowed
** transitions and the inserted intermediate states:
**
**    UNLOCKED -> SHARED
**    SHARED -> RESERVED
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
**
** With dotfile locking, we really only support state (4): EXCLUSIVE.
** But we track the other locking levels internally.
*/
static int dotlockLock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  int fd;
  char *zLockFile = (char *)pFile->lockingContext;
  int rc = SQLITE_OK;


  /* If we have any lock, then the lock file already exists.  All we have
  ** to do is adjust our internal record of the lock level.
  */
  if( pFile->locktype > NO_LOCK ){
    pFile->locktype = locktype;
#if !OS_VXWORKS
    /* Always update the timestamp on the old file */
    utimes(zLockFile, NULL);
#endif
    return SQLITE_OK;
  }

  /* grab an exclusive lock */
  fd = open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
  if( fd<0 ){
    /* failed to open/create the file, someone else may have stolen the lock */
    int tErrno = errno;
    if( EEXIST == tErrno ){
      rc = SQLITE_BUSY;
    } else {
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }
    return rc;
  }
  if( close(fd) ){
    pFile->lastErrno = errno;
    rc = SQLITE_IOERR_CLOSE;
  }

  /* got it, set the type and return ok */
  pFile->locktype = locktype;
  return rc;
}

/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** When the locking level reaches NO_LOCK, delete the lock file.
*/
static int dotlockUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  char *zLockFile = (char *)pFile->lockingContext;

  assert( pFile );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d (dotlock)\n", pFile->h, locktype,
	   pFile->locktype, getpid());
  assert( locktype<=SHARED_LOCK );

  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }

  /* To downgrade to shared, simply update our internal notion of the
  ** lock state.  No need to mess with the file on disk.
  */
  if( locktype==SHARED_LOCK ){
    pFile->locktype = SHARED_LOCK;
    return SQLITE_OK;
  }

  /* To fully unlock the database, delete the lock file */
  assert( locktype==NO_LOCK );
  if( unlink(zLockFile) ){
    int rc = 0;
    int tErrno = errno;
    if( ENOENT != tErrno ){
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    }
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
    return rc;
  }
  pFile->locktype = NO_LOCK;
  return SQLITE_OK;
}

/*
** Close a file.  Make sure the lock has been released before closing.
*/
static int dotlockClose(sqlite3_file *id) {
  int rc;
  if( id ){
    unixFile *pFile = (unixFile*)id;
    dotlockUnlock(id, NO_LOCK);
    sqlite3_free(pFile->lockingContext);
  }
  rc = closeUnixFile(id);
  return rc;
}
/****************** End of the dot-file lock implementation *******************
******************************************************************************/

/******************************************************************************
************************** Begin flock Locking ********************************
**
** Use the flock() system call to do file locking.
**
** flock() locking is like dot-file locking in that the various
** fine-grain locking levels supported by SQLite are collapsed into
** a single exclusive lock.  In other words, SHARED, RESERVED, and
** PENDING locks are the same thing as an EXCLUSIVE lock.  SQLite
** still works when you do this, but concurrency is reduced since
** only a single process can be reading the database at a time.
**
** Omit this section if SQLITE_ENABLE_LOCKING_STYLE is turned off or if
** compiling for VXWORKS.
*/
#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );

  assert( pFile );

  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    reserved = 1;
  }

  /* Otherwise see if some other process holds it. */
  if( !reserved ){
    /* attempt to get the lock */
    int lrc = flock(pFile->h, LOCK_EX | LOCK_NB);
    if( !lrc ){
      /* got the lock, unlock it */
      lrc = flock(pFile->h, LOCK_UN);
      if ( lrc ) {
        int tErrno = errno;
        /* unlock failed with an error */
        lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
        if( IS_LOCK_ERROR(lrc) ){
          pFile->lastErrno = tErrno;
          rc = lrc;
        }
      }
    } else {
      int tErrno = errno;
      reserved = 1;
      /* someone else might have it reserved */
      lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(lrc) ){
        pFile->lastErrno = tErrno;
        rc = lrc;
      }
    }
  }
  OSTRACE4("TEST WR-LOCK %d %d %d (flock)\n", pFile->h, rc, reserved);

#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
  if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
    rc = SQLITE_OK;
    reserved=1;
  }
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
  *pResOut = reserved;
  return rc;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
**     (3) PENDING_LOCK
**     (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between.  The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal.  The following chart shows the allowed
** transitions and the inserted intermediate states:
**
**    UNLOCKED -> SHARED
**    SHARED -> RESERVED
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** flock() only really support EXCLUSIVE locks.  We track intermediate
** lock states in the sqlite3_file structure, but all locks SHARED or
** above are really EXCLUSIVE locks and exclude all other processes from
** access the file.
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int flockLock(sqlite3_file *id, int locktype) {
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;

  assert( pFile );

  /* if we already have a lock, it is exclusive.
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }

  /* grab an exclusive lock */

  if (flock(pFile->h, LOCK_EX | LOCK_NB)) {
    int tErrno = errno;
    /* didn't get, must be busy */
    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
  } else {
    /* got it, set the type and return ok */
    pFile->locktype = locktype;
  }
  OSTRACE4("LOCK    %d %s %s (flock)\n", pFile->h, locktypeName(locktype),
           rc==SQLITE_OK ? "ok" : "failed");
#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
  if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
    rc = SQLITE_BUSY;
  }
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
  return rc;
}


/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int flockUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;

  assert( pFile );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d (flock)\n", pFile->h, locktype,
           pFile->locktype, getpid());
  assert( locktype<=SHARED_LOCK );

  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }

  /* shared can just be set because we always have an exclusive */
  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }

  /* no, really, unlock. */
  int rc = flock(pFile->h, LOCK_UN);
  if (rc) {
    int r, tErrno = errno;
    r = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    if( IS_LOCK_ERROR(r) ){
      pFile->lastErrno = tErrno;
    }
#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
    if( (r & SQLITE_IOERR) == SQLITE_IOERR ){
      r = SQLITE_BUSY;
    }
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */

    return r;
  } else {
    pFile->locktype = NO_LOCK;
    return SQLITE_OK;
  }
}

/*
** Close a file.
*/
static int flockClose(sqlite3_file *id) {
  if( id ){
    flockUnlock(id, NO_LOCK);
  }
  return closeUnixFile(id);
}

#endif /* SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORK */

/******************* End of the flock lock implementation *********************
******************************************************************************/

/******************************************************************************
************************ Begin Named Semaphore Locking ************************
**
** Named semaphore locking is only supported on VxWorks.
**
** Semaphore locking is like dot-lock and flock in that it really only
** supports EXCLUSIVE locking.  Only a single process can read or write
** the database file at a time.  This reduces potential concurrency, but
** makes the lock implementation much easier.
*/
#if OS_VXWORKS

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int semCheckReservedLock(sqlite3_file *id, int *pResOut) {
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );

  assert( pFile );

  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    reserved = 1;
  }

  /* Otherwise see if some other process holds it. */
  if( !reserved ){
    sem_t *pSem = pFile->pOpen->pSem;
    struct stat statBuf;

    if( sem_trywait(pSem)==-1 ){
      int tErrno = errno;
      if( EAGAIN != tErrno ){
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
        pFile->lastErrno = tErrno;
      } else {
        /* someone else has the lock when we are in NO_LOCK */
        reserved = (pFile->locktype < SHARED_LOCK);
      }
    }else{
      /* we could have it if we want it */
      sem_post(pSem);
    }
  }
  OSTRACE4("TEST WR-LOCK %d %d %d (sem)\n", pFile->h, rc, reserved);

  *pResOut = reserved;
  return rc;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
**     (3) PENDING_LOCK
**     (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between.  The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal.  The following chart shows the allowed
** transitions and the inserted intermediate states:
**
**    UNLOCKED -> SHARED
**    SHARED -> RESERVED
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** Semaphore locks only really support EXCLUSIVE locks.  We track intermediate
** lock states in the sqlite3_file structure, but all locks SHARED or
** above are really EXCLUSIVE locks and exclude all other processes from
** access the file.
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int semLock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  int fd;
  sem_t *pSem = pFile->pOpen->pSem;
  int rc = SQLITE_OK;

  /* if we already have a lock, it is exclusive.
  ** Just adjust level and punt on outta here. */
  if (pFile->locktype > NO_LOCK) {
    pFile->locktype = locktype;
    rc = SQLITE_OK;
    goto sem_end_lock;
  }

  /* lock semaphore now but bail out when already locked. */
  if( sem_trywait(pSem)==-1 ){
    rc = SQLITE_BUSY;
    goto sem_end_lock;
  }

  /* got it, set the type and return ok */
  pFile->locktype = locktype;

 sem_end_lock:
  return rc;
}

/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int semUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  sem_t *pSem = pFile->pOpen->pSem;

  assert( pFile );
  assert( pSem );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d (sem)\n", pFile->h, locktype,
	   pFile->locktype, getpid());
  assert( locktype<=SHARED_LOCK );

  /* no-op if possible */
  if( pFile->locktype==locktype ){
    return SQLITE_OK;
  }

  /* shared can just be set because we always have an exclusive */
  if (locktype==SHARED_LOCK) {
    pFile->locktype = locktype;
    return SQLITE_OK;
  }

  /* no, really unlock. */
  if ( sem_post(pSem)==-1 ) {
    int rc, tErrno = errno;
    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
    return rc;
  }
  pFile->locktype = NO_LOCK;
  return SQLITE_OK;
}

/*
 ** Close a file.
 */
static int semClose(sqlite3_file *id) {
  if( id ){
    unixFile *pFile = (unixFile*)id;
    semUnlock(id, NO_LOCK);
    assert( pFile );
    unixEnterMutex();
    releaseLockInfo(pFile->pLock);
    releaseOpenCnt(pFile->pOpen);
    unixLeaveMutex();
    closeUnixFile(id);
  }
  return SQLITE_OK;
}

#endif /* OS_VXWORKS */
/*
** Named semaphore locking is only available on VxWorks.
**
*************** End of the named semaphore lock implementation ****************
******************************************************************************/


/******************************************************************************
*************************** Begin AFP Locking *********************************
**
** AFP is the Apple Filing Protocol.  AFP is a network filesystem found
** on Apple Macintosh computers - both OS9 and OSX.
**
** Third-party implementations of AFP are available.  But this code here
** only works on OSX.
*/

#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
/*
** The afpLockingContext structure contains all afp lock specific state
*/
typedef struct afpLockingContext afpLockingContext;
struct afpLockingContext {
  unsigned long long sharedByte;
  const char *dbPath;             /* Name of the open file */
};

struct ByteRangeLockPB2
{
  unsigned long long offset;        /* offset to first byte to lock */
  unsigned long long length;        /* nbr of bytes to lock */
  unsigned long long retRangeStart; /* nbr of 1st byte locked if successful */
  unsigned char unLockFlag;         /* 1 = unlock, 0 = lock */
  unsigned char startEndFlag;       /* 1=rel to end of fork, 0=rel to start */
  int fd;                           /* file desc to assoc this lock with */
};

#define afpfsByteRangeLock2FSCTL        _IOWR('z', 23, struct ByteRangeLockPB2)

/*
** This is a utility for setting or clearing a bit-range lock on an
** AFP filesystem.
**
** Return SQLITE_OK on success, SQLITE_BUSY on failure.
*/
static int afpSetLock(
  const char *path,              /* Name of the file to be locked or unlocked */
  unixFile *pFile,               /* Open file descriptor on path */
  unsigned long long offset,     /* First byte to be locked */
  unsigned long long length,     /* Number of bytes to lock */
  int setLockFlag                /* True to set lock.  False to clear lock */
){
  struct ByteRangeLockPB2 pb;
  int err;

  pb.unLockFlag = setLockFlag ? 0 : 1;
  pb.startEndFlag = 0;
  pb.offset = offset;
  pb.length = length;
  pb.fd = pFile->h;

  OSTRACE6("AFPSETLOCK [%s] for %d%s in range %llx:%llx\n",
    (setLockFlag?"ON":"OFF"), pFile->h, (pb.fd==-1?"[testval-1]":""),
    offset, length);
  err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0);
  if ( err==-1 ) {
    int rc;
    int tErrno = errno;
    OSTRACE4("AFPSETLOCK failed to fsctl() '%s' %d %s\n",
             path, tErrno, strerror(tErrno));
#ifdef SQLITE_IGNORE_AFP_LOCK_ERRORS
    rc = SQLITE_BUSY;
#else
    rc = sqliteErrorFromPosixError(tErrno,
                    setLockFlag ? SQLITE_IOERR_LOCK : SQLITE_IOERR_UNLOCK);
#endif /* SQLITE_IGNORE_AFP_LOCK_ERRORS */
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
    return rc;
  } else {
    return SQLITE_OK;
  }
}

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int afpCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc = SQLITE_OK;
  int reserved = 0;
  unixFile *pFile = (unixFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );

  assert( pFile );
  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;

  /* Check if a thread in this process holds such a lock */
  if( pFile->locktype>SHARED_LOCK ){
    reserved = 1;
  }

  /* Otherwise see if some other process holds it.
   */
  if( !reserved ){
    /* lock the RESERVED byte */
    int lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1);
    if( SQLITE_OK==lrc ){
      /* if we succeeded in taking the reserved lock, unlock it to restore
      ** the original state */
      lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1, 0);
    } else {
      /* if we failed to get the lock then someone else must have it */
      reserved = 1;
    }
    if( IS_LOCK_ERROR(lrc) ){
      rc=lrc;
    }
  }

  OSTRACE4("TEST WR-LOCK %d %d %d (afp)\n", pFile->h, rc, reserved);

  *pResOut = reserved;
  return rc;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
**     (3) PENDING_LOCK
**     (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between.  The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal.  The following chart shows the allowed
** transitions and the inserted intermediate states:
**
**    UNLOCKED -> SHARED
**    SHARED -> RESERVED
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int afpLock(sqlite3_file *id, int locktype){
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;

  assert( pFile );
  OSTRACE5("LOCK    %d %s was %s pid=%d (afp)\n", pFile->h,
         locktypeName(locktype), locktypeName(pFile->locktype), getpid());

  /* If there is already a lock of this type or more restrictive on the
  ** unixFile, do nothing. Don't use the afp_end_lock: exit path, as
  ** unixEnterMutex() hasn't been called yet.
  */
  if( pFile->locktype>=locktype ){
    OSTRACE3("LOCK    %d %s ok (already held) (afp)\n", pFile->h,
           locktypeName(locktype));
    return SQLITE_OK;
  }

  /* Make sure the locking sequence is correct
  */
  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
  assert( locktype!=PENDING_LOCK );
  assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );

  /* This mutex is needed because pFile->pLock is shared across threads
  */
  unixEnterMutex();

  /* Make sure the current thread owns the pFile.
  */
  rc = transferOwnership(pFile);
  if( rc!=SQLITE_OK ){
    unixLeaveMutex();
    return rc;
  }

  /* A PENDING lock is needed before acquiring a SHARED lock and before
  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
  ** be released.
  */
  if( locktype==SHARED_LOCK
      || (locktype==EXCLUSIVE_LOCK && pFile->locktype<PENDING_LOCK)
  ){
    int failed;
    failed = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 1);
    if (failed) {
      rc = failed;
      goto afp_end_lock;
    }
  }

  /* If control gets to this point, then actually go ahead and make
  ** operating system calls for the specified lock.
  */
  if( locktype==SHARED_LOCK ){
    int lk, lrc1, lrc2;
    int lrc1Errno = 0;

    /* Now get the read-lock SHARED_LOCK */
    /* note that the quality of the randomness doesn't matter that much */
    lk = random();
    context->sharedByte = (lk & 0x7fffffff)%(SHARED_SIZE - 1);
    lrc1 = afpSetLock(context->dbPath, pFile,
          SHARED_FIRST+context->sharedByte, 1, 1);
    if( IS_LOCK_ERROR(lrc1) ){
      lrc1Errno = pFile->lastErrno;
    }
    /* Drop the temporary PENDING lock */
    lrc2 = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 0);

    if( IS_LOCK_ERROR(lrc1) ) {
      pFile->lastErrno = lrc1Errno;
      rc = lrc1;
      goto afp_end_lock;
    } else if( IS_LOCK_ERROR(lrc2) ){
      rc = lrc2;
      goto afp_end_lock;
    } else if( lrc1 != SQLITE_OK ) {
      rc = lrc1;
    } else {
      pFile->locktype = SHARED_LOCK;
      pFile->pOpen->nLock++;
    }
  }else{
    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
    ** assumed that there is a SHARED or greater lock on the file
    ** already.
    */
    int failed = 0;
    assert( 0!=pFile->locktype );
    if (locktype >= RESERVED_LOCK && pFile->locktype < RESERVED_LOCK) {
        /* Acquire a RESERVED lock */
        failed = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1);
    }
    if (!failed && locktype == EXCLUSIVE_LOCK) {
      /* Acquire an EXCLUSIVE lock */

      /* Remove the shared lock before trying the range.  we'll need to
      ** reestablish the shared lock if we can't get the  afpUnlock
      */
      if( !(failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST +
                         context->sharedByte, 1, 0)) ){
        int failed2 = SQLITE_OK;
        /* now attemmpt to get the exclusive lock range */
        failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST,
                               SHARED_SIZE, 1);
        if( failed && (failed2 = afpSetLock(context->dbPath, pFile,
                       SHARED_FIRST + context->sharedByte, 1, 1)) ){
          /* Can't reestablish the shared lock.  Sqlite can't deal, this is
          ** a critical I/O error
          */
          rc = ((failed & SQLITE_IOERR) == SQLITE_IOERR) ? failed2 :
               SQLITE_IOERR_LOCK;
          goto afp_end_lock;
        }
      }else{
        rc = failed;
      }
    }
    if( failed ){
      rc = failed;
    }
  }

  if( rc==SQLITE_OK ){
    pFile->locktype = locktype;
  }else if( locktype==EXCLUSIVE_LOCK ){
    pFile->locktype = PENDING_LOCK;
  }

afp_end_lock:
  unixLeaveMutex();
  OSTRACE4("LOCK    %d %s %s (afp)\n", pFile->h, locktypeName(locktype),
         rc==SQLITE_OK ? "ok" : "failed");
  return rc;
}

/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int afpUnlock(sqlite3_file *id, int locktype) {
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  afpLockingContext *pCtx = (afpLockingContext *) pFile->lockingContext;

  assert( pFile );
  OSTRACE5("UNLOCK  %d %d was %d pid=%d (afp)\n", pFile->h, locktype,
         pFile->locktype, getpid());

  assert( locktype<=SHARED_LOCK );
  if( pFile->locktype<=locktype ){
    return SQLITE_OK;
  }
  if( CHECK_THREADID(pFile) ){
    return SQLITE_MISUSE_BKPT;
  }
  unixEnterMutex();
  if( pFile->locktype>SHARED_LOCK ){

    if( pFile->locktype==EXCLUSIVE_LOCK ){
      rc = afpSetLock(pCtx->dbPath, pFile, SHARED_FIRST, SHARED_SIZE, 0);
      if( rc==SQLITE_OK && locktype==SHARED_LOCK ){
        /* only re-establish the shared lock if necessary */
        int sharedLockByte = SHARED_FIRST+pCtx->sharedByte;
        rc = afpSetLock(pCtx->dbPath, pFile, sharedLockByte, 1, 1);
      }
    }
    if( rc==SQLITE_OK && pFile->locktype>=PENDING_LOCK ){
      rc = afpSetLock(pCtx->dbPath, pFile, PENDING_BYTE, 1, 0);
    }
    if( rc==SQLITE_OK && pFile->locktype>=RESERVED_LOCK ){
      rc = afpSetLock(pCtx->dbPath, pFile, RESERVED_BYTE, 1, 0);
    }
  }else if( locktype==NO_LOCK ){
    /* clear the shared lock */
    int sharedLockByte = SHARED_FIRST+pCtx->sharedByte;
    rc = afpSetLock(pCtx->dbPath, pFile, sharedLockByte, 1, 0);
  }

  if( rc==SQLITE_OK ){
    if( locktype==NO_LOCK ){
      struct unixOpenCnt *pOpen = pFile->pOpen;
      pOpen->nLock--;
      assert( pOpen->nLock>=0 );
      if( pOpen->nLock==0 ){
        rc = closePendingFds(pFile);
      }
    }
  }
  unixLeaveMutex();
  if( rc==SQLITE_OK ){
    pFile->locktype = locktype;
  }
  return rc;
}

/*
** Close a file & cleanup AFP specific locking context
*/
static int afpClose(sqlite3_file *id) {
  if( id ){
    unixFile *pFile = (unixFile*)id;
    afpUnlock(id, NO_LOCK);
    unixEnterMutex();
    if( pFile->pOpen && pFile->pOpen->nLock ){
      /* If there are outstanding locks, do not actually close the file just
      ** yet because that would clear those locks.  Instead, add the file
      ** descriptor to pOpen->aPending.  It will be automatically closed when
      ** the last lock is cleared.
      */
      setPendingFd(pFile);
    }
    releaseOpenCnt(pFile->pOpen);
    sqlite3_free(pFile->lockingContext);
    closeUnixFile(id);
    unixLeaveMutex();
  }
  return SQLITE_OK;
}

#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
/*
** The code above is the AFP lock implementation.  The code is specific
** to MacOSX and does not work on other unix platforms.  No alternative
** is available.  If you don't compile for a mac, then the "unix-afp"
** VFS is not available.
**
********************* End of the AFP lock implementation **********************
******************************************************************************/


/******************************************************************************
**************** Non-locking sqlite3_file methods *****************************
**
** The next division contains implementations for all methods of the
** sqlite3_file object other than the locking methods.  The locking
** methods were defined in divisions above (one locking method per
** division).  Those methods that are common to all locking modes
** are gather together into this division.
*/

/*
** Seek to the offset passed as the second argument, then read cnt
** bytes into pBuf. Return the number of bytes actually read.
**
** NB:  If you define USE_PREAD or USE_PREAD64, then it might also
** be necessary to define _XOPEN_SOURCE to be 500.  This varies from
** one system to another.  Since SQLite does not define USE_PREAD
** any any form by default, we will not attempt to define _XOPEN_SOURCE.
** See tickets #2741 and #2681.
**
** To avoid stomping the errno value on a failed read the lastErrno value
** is set before returning.
*/
static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
  int got;
  i64 newOffset;
  TIMER_START;
#if defined(USE_PREAD)
  got = pread(id->h, pBuf, cnt, offset);
  SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
  got = pread64(id->h, pBuf, cnt, offset);
  SimulateIOError( got = -1 );
#else
  newOffset = lseek(id->h, offset, SEEK_SET);
  SimulateIOError( newOffset-- );
  if( newOffset!=offset ){
    if( newOffset == -1 ){
      ((unixFile*)id)->lastErrno = errno;
    }else{
      ((unixFile*)id)->lastErrno = 0;
    }
    return -1;
  }
  got = read(id->h, pBuf, cnt);
#endif
  TIMER_END;
  if( got<0 ){
    ((unixFile*)id)->lastErrno = errno;
  }
  OSTRACE5("READ    %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED);
  return got;
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int unixRead(
  sqlite3_file *id,
  void *pBuf,
  int amt,
  sqlite3_int64 offset
){
  unixFile *pFile = (unixFile *)id;
  int got;
  assert( id );

  /* If this is a database file (not a journal, master-journal or temp
  ** file), the bytes in the locking range should never be read or written. */
  assert( pFile->pUnused==0
       || offset>=PENDING_BYTE+512
       || offset+amt<=PENDING_BYTE
  );

  got = seekAndRead(pFile, offset, pBuf, amt);
  if( got==amt ){
    return SQLITE_OK;
  }else if( got<0 ){
    /* lastErrno set by seekAndRead */
    return SQLITE_IOERR_READ;
  }else{
    pFile->lastErrno = 0; /* not a system error */
    /* Unread parts of the buffer must be zero-filled */
    memset(&((char*)pBuf)[got], 0, amt-got);
    return SQLITE_IOERR_SHORT_READ;
  }
}

/*
** Seek to the offset in id->offset then read cnt bytes into pBuf.
** Return the number of bytes actually read.  Update the offset.
**
** To avoid stomping the errno value on a failed write the lastErrno value
** is set before returning.
*/
static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){
  int got;
  i64 newOffset;
  TIMER_START;
#if defined(USE_PREAD)
  got = pwrite(id->h, pBuf, cnt, offset);
#elif defined(USE_PREAD64)
  got = pwrite64(id->h, pBuf, cnt, offset);
#else
  newOffset = lseek(id->h, offset, SEEK_SET);
  if( newOffset!=offset ){
    if( newOffset == -1 ){
      ((unixFile*)id)->lastErrno = errno;
    }else{
      ((unixFile*)id)->lastErrno = 0;
    }
    return -1;
  }
  got = write(id->h, pBuf, cnt);
#endif
  TIMER_END;
  if( got<0 ){
    ((unixFile*)id)->lastErrno = errno;
  }

  OSTRACE5("WRITE   %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED);
  return got;
}


/*
** Write data from a buffer into a file.  Return SQLITE_OK on success
** or some other error code on failure.
*/
static int unixWrite(
  sqlite3_file *id,
  const void *pBuf,
  int amt,
  sqlite3_int64 offset
){
  unixFile *pFile = (unixFile*)id;
  int wrote = 0;
  assert( id );
  assert( amt>0 );

  /* If this is a database file (not a journal, master-journal or temp
  ** file), the bytes in the locking range should never be read or written. */
  assert( pFile->pUnused==0
       || offset>=PENDING_BYTE+512
       || offset+amt<=PENDING_BYTE
  );

#ifndef NDEBUG
  /* If we are doing a normal write to a database file (as opposed to
  ** doing a hot-journal rollback or a write to some file other than a
  ** normal database file) then record the fact that the database
  ** has changed.  If the transaction counter is modified, record that
  ** fact too.
  */
  if( pFile->inNormalWrite ){
    pFile->dbUpdate = 1;  /* The database has been modified */
    if( offset<=24 && offset+amt>=27 ){
      int rc;
      char oldCntr[4];
      SimulateIOErrorBenign(1);
      rc = seekAndRead(pFile, 24, oldCntr, 4);
      SimulateIOErrorBenign(0);
      if( rc!=4 || memcmp(oldCntr, &((char*)pBuf)[24-offset], 4)!=0 ){
        pFile->transCntrChng = 1;  /* The transaction counter has changed */
      }
    }
  }
#endif

  while( amt>0 && (wrote = seekAndWrite(pFile, offset, pBuf, amt))>0 ){
    amt -= wrote;
    offset += wrote;
    pBuf = &((char*)pBuf)[wrote];
  }
  SimulateIOError(( wrote=(-1), amt=1 ));
  SimulateDiskfullError(( wrote=0, amt=1 ));
  if( amt>0 ){
    if( wrote<0 ){
      /* lastErrno set by seekAndWrite */
      return SQLITE_IOERR_WRITE;
    }else{
      pFile->lastErrno = 0; /* not a system error */
      return SQLITE_FULL;
    }
  }
  return SQLITE_OK;
}

#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs.  This is used to test
** that syncs and fullsyncs are occurring at the right times.
*/
SQLITE_API int sqlite3_sync_count = 0;
SQLITE_API int sqlite3_fullsync_count = 0;
#endif

/*
** We do not trust systems to provide a working fdatasync().  Some do.
** Others do no.  To be safe, we will stick with the (slower) fsync().
** If you know that your system does support fdatasync() correctly,
** then simply compile with -Dfdatasync=fdatasync
*/
#if !defined(fdatasync) && !defined(__linux__)
# define fdatasync fsync
#endif

/*
** Define HAVE_FULLFSYNC to 0 or 1 depending on whether or not
** the F_FULLFSYNC macro is defined.  F_FULLFSYNC is currently
** only available on Mac OS X.  But that could change.
*/
#ifdef F_FULLFSYNC
# define HAVE_FULLFSYNC 1
#else
# define HAVE_FULLFSYNC 0
#endif


/*
** The fsync() system call does not work as advertised on many
** unix systems.  The following procedure is an attempt to make
** it work better.
**
** The SQLITE_NO_SYNC macro disables all fsync()s.  This is useful
** for testing when we want to run through the test suite quickly.
** You are strongly advised *not* to deploy with SQLITE_NO_SYNC
** enabled, however, since with SQLITE_NO_SYNC enabled, an OS crash
** or power failure will likely corrupt the database file.
**
** SQLite sets the dataOnly flag if the size of the file is unchanged.
** The idea behind dataOnly is that it should only write the file content
** to disk, not the inode.  We only set dataOnly if the file size is
** unchanged since the file size is part of the inode.  However,
** Ted Ts'o tells us that fdatasync() will also write the inode if the
** file size has changed.  The only real difference between fdatasync()
** and fsync(), Ted tells us, is that fdatasync() will not flush the
** inode if the mtime or owner or other inode attributes have changed.
** We only care about the file size, not the other file attributes, so
** as far as SQLite is concerned, an fdatasync() is always adequate.
** So, we always use fdatasync() if it is available, regardless of
** the value of the dataOnly flag.
*/
static int full_fsync(int fd, int fullSync, int dataOnly){
  int rc;

  /* The following "ifdef/elif/else/" block has the same structure as
  ** the one below. It is replicated here solely to avoid cluttering
  ** up the real code with the UNUSED_PARAMETER() macros.
  */
#ifdef SQLITE_NO_SYNC
  UNUSED_PARAMETER(fd);
  UNUSED_PARAMETER(fullSync);
  UNUSED_PARAMETER(dataOnly);
#elif HAVE_FULLFSYNC
  UNUSED_PARAMETER(dataOnly);
#else
  UNUSED_PARAMETER(fullSync);
  UNUSED_PARAMETER(dataOnly);
#endif

  /* Record the number of times that we do a normal fsync() and
  ** FULLSYNC.  This is used during testing to verify that this procedure
  ** gets called with the correct arguments.
  */
#ifdef SQLITE_TEST
  if( fullSync ) sqlite3_fullsync_count++;
  sqlite3_sync_count++;
#endif

  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
  ** no-op
  */
#ifdef SQLITE_NO_SYNC
  rc = SQLITE_OK;
#elif HAVE_FULLFSYNC
  if( fullSync ){
    rc = fcntl(fd, F_FULLFSYNC, 0);
  }else{
    rc = 1;
  }
  /* If the FULLFSYNC failed, fall back to attempting an fsync().
  ** It shouldn't be possible for fullfsync to fail on the local
  ** file system (on OSX), so failure indicates that FULLFSYNC
  ** isn't supported for this file system. So, attempt an fsync
  ** and (for now) ignore the overhead of a superfluous fcntl call.
  ** It'd be better to detect fullfsync support once and avoid
  ** the fcntl call every time sync is called.
  */
  if( rc ) rc = fsync(fd);

#else
  rc = fdatasync(fd);
#if OS_VXWORKS
  if( rc==-1 && errno==ENOTSUP ){
    rc = fsync(fd);
  }
#endif /* OS_VXWORKS */
#endif /* ifdef SQLITE_NO_SYNC elif HAVE_FULLFSYNC */

  if( OS_VXWORKS && rc!= -1 ){
    rc = 0;
  }
  return rc;
}

/*
** Make sure all writes to a particular file are committed to disk.
**
** If dataOnly==0 then both the file itself and its metadata (file
** size, access time, etc) are synced.  If dataOnly!=0 then only the
** file data is synced.
**
** Under Unix, also make sure that the directory entry for the file
** has been created by fsync-ing the directory that contains the file.
** If we do not do this and we encounter a power failure, the directory
** entry for the journal might not exist after we reboot.  The next
** SQLite to access the file will not know that the journal exists (because
** the directory entry for the journal was never created) and the transaction
** will not roll back - possibly leading to database corruption.
*/
static int unixSync(sqlite3_file *id, int flags){
  int rc;
  unixFile *pFile = (unixFile*)id;

  int isDataOnly = (flags&SQLITE_SYNC_DATAONLY);
  int isFullsync = (flags&0x0F)==SQLITE_SYNC_FULL;

  /* Check that one of SQLITE_SYNC_NORMAL or FULL was passed */
  assert((flags&0x0F)==SQLITE_SYNC_NORMAL
      || (flags&0x0F)==SQLITE_SYNC_FULL
  );

  /* Unix cannot, but some systems may return SQLITE_FULL from here. This
  ** line is to test that doing so does not cause any problems.
  */
  SimulateDiskfullError( return SQLITE_FULL );

  assert( pFile );
  OSTRACE2("SYNC    %-3d\n", pFile->h);
  rc = full_fsync(pFile->h, isFullsync, isDataOnly);
  SimulateIOError( rc=1 );
  if( rc ){
    pFile->lastErrno = errno;
    return SQLITE_IOERR_FSYNC;
  }
  if( pFile->dirfd>=0 ){
    int err;
    OSTRACE4("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd,
            HAVE_FULLFSYNC, isFullsync);
#ifndef SQLITE_DISABLE_DIRSYNC
    /* The directory sync is only attempted if full_fsync is
    ** turned off or unavailable.  If a full_fsync occurred above,
    ** then the directory sync is superfluous.
    */
    if( (!HAVE_FULLFSYNC || !isFullsync) && full_fsync(pFile->dirfd,0,0) ){
       /*
       ** We have received multiple reports of fsync() returning
       ** errors when applied to directories on certain file systems.
       ** A failed directory sync is not a big deal.  So it seems
       ** better to ignore the error.  Ticket #1657
       */
       /* pFile->lastErrno = errno; */
       /* return SQLITE_IOERR; */
    }
#endif
    err = close(pFile->dirfd); /* Only need to sync once, so close the */
    if( err==0 ){              /* directory when we are done */
      pFile->dirfd = -1;
    }else{
      pFile->lastErrno = errno;
      rc = SQLITE_IOERR_DIR_CLOSE;
    }
  }
  return rc;
}

/*
** Truncate an open file to a specified size
*/
static int unixTruncate(sqlite3_file *id, i64 nByte){
  int rc;
  assert( id );
  SimulateIOError( return SQLITE_IOERR_TRUNCATE );
  rc = ftruncate(((unixFile*)id)->h, (off_t)nByte);
  if( rc ){
    ((unixFile*)id)->lastErrno = errno;
    return SQLITE_IOERR_TRUNCATE;
  }else{
#ifndef NDEBUG
    /* If we are doing a normal write to a database file (as opposed to
    ** doing a hot-journal rollback or a write to some file other than a
    ** normal database file) and we truncate the file to zero length,
    ** that effectively updates the change counter.  This might happen
    ** when restoring a database using the backup API from a zero-length
    ** source.
    */
    if( ((unixFile*)id)->inNormalWrite && nByte==0 ){
      ((unixFile*)id)->transCntrChng = 1;
    }
#endif

    return SQLITE_OK;
  }
}

/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(sqlite3_file *id, i64 *pSize){
  int rc;
  struct stat buf;
  assert( id );
  rc = fstat(((unixFile*)id)->h, &buf);
  SimulateIOError( rc=1 );
  if( rc!=0 ){
    ((unixFile*)id)->lastErrno = errno;
    return SQLITE_IOERR_FSTAT;
  }
  *pSize = buf.st_size;

  /* When opening a zero-size database, the findLockInfo() procedure
  ** writes a single byte into that file in order to work around a bug
  ** in the OS-X msdos filesystem.  In order to avoid problems with upper
  ** layers, we need to report this file size as zero even though it is
  ** really 1.   Ticket #3260.
  */
  if( *pSize==1 ) *pSize = 0;


  return SQLITE_OK;
}

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
/*
** Handler for proxy-locking file-control verbs.  Defined below in the
** proxying locking division.
*/
static int proxyFileControl(sqlite3_file*,int,void*);
#endif


/*
** Information and control of an open file handle.
*/
static int unixFileControl(sqlite3_file *id, int op, void *pArg){
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = ((unixFile*)id)->locktype;
      return SQLITE_OK;
    }
    case SQLITE_LAST_ERRNO: {
      *(int*)pArg = ((unixFile*)id)->lastErrno;
      return SQLITE_OK;
    }
#ifndef NDEBUG
    /* The pager calls this method to signal that it has done
    ** a rollback and that the database is therefore unchanged and
    ** it hence it is OK for the transaction change counter to be
    ** unchanged.
    */
    case SQLITE_FCNTL_DB_UNCHANGED: {
      ((unixFile*)id)->dbUpdate = 0;
      return SQLITE_OK;
    }
#endif
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
    case SQLITE_SET_LOCKPROXYFILE:
    case SQLITE_GET_LOCKPROXYFILE: {
      return proxyFileControl(id,op,pArg);
    }
#endif /* SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) */
  }
  return SQLITE_ERROR;
}

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
** larger for some devices.
**
** SQLite code assumes this function cannot fail. It also assumes that
** if two files are created in the same file-system directory (i.e.
** a database and its journal file) that the sector size will be the
** same for both.
*/
static int unixSectorSize(sqlite3_file *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return SQLITE_DEFAULT_SECTOR_SIZE;
}

/*
** Return the device characteristics for the file. This is always 0 for unix.
*/
static int unixDeviceCharacteristics(sqlite3_file *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  return 0;
}

/*
** Here ends the implementation of all sqlite3_file methods.
**
********************** End sqlite3_file Methods *******************************
******************************************************************************/

/*
** This division contains definitions of sqlite3_io_methods objects that
** implement various file locking strategies.  It also contains definitions
** of "finder" functions.  A finder-function is used to locate the appropriate
** sqlite3_io_methods object for a particular database file.  The pAppData
** field of the sqlite3_vfs VFS objects are initialized to be pointers to
** the correct finder-function for that VFS.
**
** Most finder functions return a pointer to a fixed sqlite3_io_methods
** object.  The only interesting finder-function is autolockIoFinder, which
** looks at the filesystem type and tries to guess the best locking
** strategy from that.
**
** For finder-funtion F, two objects are created:
**
**    (1) The real finder-function named "FImpt()".
**
**    (2) A constant pointer to this function named just "F".
**
**
** A pointer to the F pointer is used as the pAppData value for VFS
** objects.  We have to do this instead of letting pAppData point
** directly at the finder-function since C90 rules prevent a void*
** from be cast into a function pointer.
**
**
** Each instance of this macro generates two objects:
**
**   *  A constant sqlite3_io_methods object call METHOD that has locking
**      methods CLOSE, LOCK, UNLOCK, CKRESLOCK.
**
**   *  An I/O method finder function called FINDER that returns a pointer
**      to the METHOD object in the previous bullet.
*/
#define IOMETHODS(FINDER, METHOD, CLOSE, LOCK, UNLOCK, CKLOCK)               \
static const sqlite3_io_methods METHOD = {                                   \
   1,                          /* iVersion */                                \
   CLOSE,                      /* xClose */                                  \
   unixRead,                   /* xRead */                                   \
   unixWrite,                  /* xWrite */                                  \
   unixTruncate,               /* xTruncate */                               \
   unixSync,                   /* xSync */                                   \
   unixFileSize,               /* xFileSize */                               \
   LOCK,                       /* xLock */                                   \
   UNLOCK,                     /* xUnlock */                                 \
   CKLOCK,                     /* xCheckReservedLock */                      \
   unixFileControl,            /* xFileControl */                            \
   unixSectorSize,             /* xSectorSize */                             \
   unixDeviceCharacteristics   /* xDeviceCapabilities */                     \
};                                                                           \
static const sqlite3_io_methods *FINDER##Impl(const char *z, unixFile *p){   \
  UNUSED_PARAMETER(z); UNUSED_PARAMETER(p);                                  \
  return &METHOD;                                                            \
}                                                                            \
static const sqlite3_io_methods *(*const FINDER)(const char*,unixFile *p)    \
    = FINDER##Impl;

/*
** Here are all of the sqlite3_io_methods objects for each of the
** locking strategies.  Functions that return pointers to these methods
** are also created.
*/
IOMETHODS(
  posixIoFinder,            /* Finder function name */
  posixIoMethods,           /* sqlite3_io_methods object name */
  unixClose,                /* xClose method */
  unixLock,                 /* xLock method */
  unixUnlock,               /* xUnlock method */
  unixCheckReservedLock     /* xCheckReservedLock method */
)
IOMETHODS(
  nolockIoFinder,           /* Finder function name */
  nolockIoMethods,          /* sqlite3_io_methods object name */
  nolockClose,              /* xClose method */
  nolockLock,               /* xLock method */
  nolockUnlock,             /* xUnlock method */
  nolockCheckReservedLock   /* xCheckReservedLock method */
)
IOMETHODS(
  dotlockIoFinder,          /* Finder function name */
  dotlockIoMethods,         /* sqlite3_io_methods object name */
  dotlockClose,             /* xClose method */
  dotlockLock,              /* xLock method */
  dotlockUnlock,            /* xUnlock method */
  dotlockCheckReservedLock  /* xCheckReservedLock method */
)

#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS
IOMETHODS(
  flockIoFinder,            /* Finder function name */
  flockIoMethods,           /* sqlite3_io_methods object name */
  flockClose,               /* xClose method */
  flockLock,                /* xLock method */
  flockUnlock,              /* xUnlock method */
  flockCheckReservedLock    /* xCheckReservedLock method */
)
#endif

#if OS_VXWORKS
IOMETHODS(
  semIoFinder,              /* Finder function name */
  semIoMethods,             /* sqlite3_io_methods object name */
  semClose,                 /* xClose method */
  semLock,                  /* xLock method */
  semUnlock,                /* xUnlock method */
  semCheckReservedLock      /* xCheckReservedLock method */
)
#endif

#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
IOMETHODS(
  afpIoFinder,              /* Finder function name */
  afpIoMethods,             /* sqlite3_io_methods object name */
  afpClose,                 /* xClose method */
  afpLock,                  /* xLock method */
  afpUnlock,                /* xUnlock method */
  afpCheckReservedLock      /* xCheckReservedLock method */
)
#endif

/*
** The "Whole File Locking" finder returns the same set of methods as
** the posix locking finder.  But it also sets the SQLITE_WHOLE_FILE_LOCKING
** flag to force the posix advisory locks to cover the whole file instead
** of just a small span of bytes near the 1GiB boundary.  Whole File Locking
** is useful on NFS-mounted files since it helps NFS to maintain cache
** coherency.  But it is a detriment to other filesystems since it runs
** slower.
*/
static const sqlite3_io_methods *posixWflIoFinderImpl(const char*z, unixFile*p){
  UNUSED_PARAMETER(z);
  p->fileFlags = SQLITE_WHOLE_FILE_LOCKING;
  return &posixIoMethods;
}
static const sqlite3_io_methods
  *(*const posixWflIoFinder)(const char*,unixFile *p) = posixWflIoFinderImpl;

/*
** The proxy locking method is a "super-method" in the sense that it
** opens secondary file descriptors for the conch and lock files and
** it uses proxy, dot-file, AFP, and flock() locking methods on those
** secondary files.  For this reason, the division that implements
** proxy locking is located much further down in the file.  But we need
** to go ahead and define the sqlite3_io_methods and finder function
** for proxy locking here.  So we forward declare the I/O methods.
*/
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
static int proxyClose(sqlite3_file*);
static int proxyLock(sqlite3_file*, int);
static int proxyUnlock(sqlite3_file*, int);
static int proxyCheckReservedLock(sqlite3_file*, int*);
IOMETHODS(
  proxyIoFinder,            /* Finder function name */
  proxyIoMethods,           /* sqlite3_io_methods object name */
  proxyClose,               /* xClose method */
  proxyLock,                /* xLock method */
  proxyUnlock,              /* xUnlock method */
  proxyCheckReservedLock    /* xCheckReservedLock method */
)
#endif


#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
/*
** This "finder" function attempts to determine the best locking strategy
** for the database file "filePath".  It then returns the sqlite3_io_methods
** object that implements that strategy.
**
** This is for MacOSX only.
*/
static const sqlite3_io_methods *autolockIoFinderImpl(
  const char *filePath,    /* name of the database file */
  unixFile *pNew           /* open file object for the database file */
){
  static const struct Mapping {
    const char *zFilesystem;              /* Filesystem type name */
    const sqlite3_io_methods *pMethods;   /* Appropriate locking method */
  } aMap[] = {
    { "hfs",    &posixIoMethods },
    { "ufs",    &posixIoMethods },
    { "afpfs",  &afpIoMethods },
#ifdef SQLITE_ENABLE_AFP_LOCKING_SMB
    { "smbfs",  &afpIoMethods },
#else
    { "smbfs",  &flockIoMethods },
#endif
    { "webdav", &nolockIoMethods },
    { 0, 0 }
  };
  int i;
  struct statfs fsInfo;
  struct flock lockInfo;

  if( !filePath ){
    /* If filePath==NULL that means we are dealing with a transient file
    ** that does not need to be locked. */
    return &nolockIoMethods;
  }
  if( statfs(filePath, &fsInfo) != -1 ){
    if( fsInfo.f_flags & MNT_RDONLY ){
      return &nolockIoMethods;
    }
    for(i=0; aMap[i].zFilesystem; i++){
      if( strcmp(fsInfo.f_fstypename, aMap[i].zFilesystem)==0 ){
        return aMap[i].pMethods;
      }
    }
  }

  /* Default case. Handles, amongst others, "nfs".
  ** Test byte-range lock using fcntl(). If the call succeeds,
  ** assume that the file-system supports POSIX style locks.
  */
  lockInfo.l_len = 1;
  lockInfo.l_start = 0;
  lockInfo.l_whence = SEEK_SET;
  lockInfo.l_type = F_RDLCK;
  if( fcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
    pNew->fileFlags = SQLITE_WHOLE_FILE_LOCKING;
    return &posixIoMethods;
  }else{
    return &dotlockIoMethods;
  }
}
static const sqlite3_io_methods
  *(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;

#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */

#if OS_VXWORKS && SQLITE_ENABLE_LOCKING_STYLE
/*
** This "finder" function attempts to determine the best locking strategy
** for the database file "filePath".  It then returns the sqlite3_io_methods
** object that implements that strategy.
**
** This is for VXWorks only.
*/
static const sqlite3_io_methods *autolockIoFinderImpl(
  const char *filePath,    /* name of the database file */
  unixFile *pNew           /* the open file object */
){
  struct flock lockInfo;

  if( !filePath ){
    /* If filePath==NULL that means we are dealing with a transient file
    ** that does not need to be locked. */
    return &nolockIoMethods;
  }

  /* Test if fcntl() is supported and use POSIX style locks.
  ** Otherwise fall back to the named semaphore method.
  */
  lockInfo.l_len = 1;
  lockInfo.l_start = 0;
  lockInfo.l_whence = SEEK_SET;
  lockInfo.l_type = F_RDLCK;
  if( fcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
    return &posixIoMethods;
  }else{
    return &semIoMethods;
  }
}
static const sqlite3_io_methods
  *(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;

#endif /* OS_VXWORKS && SQLITE_ENABLE_LOCKING_STYLE */

/*
** An abstract type for a pointer to a IO method finder function:
*/
typedef const sqlite3_io_methods *(*finder_type)(const char*,unixFile*);


/****************************************************************************
**************************** sqlite3_vfs methods ****************************
**
** This division contains the implementation of methods on the
** sqlite3_vfs object.
*/

/*
** Initialize the contents of the unixFile structure pointed to by pId.
*/
static int fillInUnixFile(
  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
  int h,                  /* Open file descriptor of file being opened */
  int dirfd,              /* Directory file descriptor */
  sqlite3_file *pId,      /* Write to the unixFile structure here */
  const char *zFilename,  /* Name of the file being opened */
  int noLock,             /* Omit locking if true */
  int isDelete            /* Delete on close if true */
){
  const sqlite3_io_methods *pLockingStyle;
  unixFile *pNew = (unixFile *)pId;
  int rc = SQLITE_OK;

  assert( pNew->pLock==NULL );
  assert( pNew->pOpen==NULL );

  /* Parameter isDelete is only used on vxworks. Express this explicitly
  ** here to prevent compiler warnings about unused parameters.
  */
  UNUSED_PARAMETER(isDelete);

  OSTRACE3("OPEN    %-3d %s\n", h, zFilename);
  pNew->h = h;
  pNew->dirfd = dirfd;
  SET_THREADID(pNew);
  pNew->fileFlags = 0;

#if OS_VXWORKS
  pNew->pId = vxworksFindFileId(zFilename);
  if( pNew->pId==0 ){
    noLock = 1;
    rc = SQLITE_NOMEM;
  }
#endif

  if( noLock ){
    pLockingStyle = &nolockIoMethods;
  }else{
    pLockingStyle = (**(finder_type*)pVfs->pAppData)(zFilename, pNew);
#if SQLITE_ENABLE_LOCKING_STYLE
    /* Cache zFilename in the locking context (AFP and dotlock override) for
    ** proxyLock activation is possible (remote proxy is based on db name)
    ** zFilename remains valid until file is closed, to support */
    pNew->lockingContext = (void*)zFilename;
#endif
  }

  if( pLockingStyle == &posixIoMethods ){
    unixEnterMutex();
    rc = findLockInfo(pNew, &pNew->pLock, &pNew->pOpen);
    if( rc!=SQLITE_OK ){
      /* If an error occured in findLockInfo(), close the file descriptor
      ** immediately, before releasing the mutex. findLockInfo() may fail
      ** in two scenarios:
      **
      **   (a) A call to fstat() failed.
      **   (b) A malloc failed.
      **
      ** Scenario (b) may only occur if the process is holding no other
      ** file descriptors open on the same file. If there were other file
      ** descriptors on this file, then no malloc would be required by
      ** findLockInfo(). If this is the case, it is quite safe to close
      ** handle h - as it is guaranteed that no posix locks will be released
      ** by doing so.
      **
      ** If scenario (a) caused the error then things are not so safe. The
      ** implicit assumption here is that if fstat() fails, things are in
      ** such bad shape that dropping a lock or two doesn't matter much.
      */
      close(h);
      h = -1;
    }
    unixLeaveMutex();
  }

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
  else if( pLockingStyle == &afpIoMethods ){
    /* AFP locking uses the file path so it needs to be included in
    ** the afpLockingContext.
    */
    afpLockingContext *pCtx;
    pNew->lockingContext = pCtx = sqlite3_malloc( sizeof(*pCtx) );
    if( pCtx==0 ){
      rc = SQLITE_NOMEM;
    }else{
      /* NB: zFilename exists and remains valid until the file is closed
      ** according to requirement F11141.  So we do not need to make a
      ** copy of the filename. */
      pCtx->dbPath = zFilename;
      srandomdev();
      unixEnterMutex();
      rc = findLockInfo(pNew, NULL, &pNew->pOpen);
      unixLeaveMutex();
    }
  }
#endif

  else if( pLockingStyle == &dotlockIoMethods ){
    /* Dotfile locking uses the file path so it needs to be included in
    ** the dotlockLockingContext
    */
    char *zLockFile;
    int nFilename;
    nFilename = (int)strlen(zFilename) + 6;
    zLockFile = (char *)sqlite3_malloc(nFilename);
    if( zLockFile==0 ){
      rc = SQLITE_NOMEM;
    }else{
      sqlite3_snprintf(nFilename, zLockFile, "%s" DOTLOCK_SUFFIX, zFilename);
    }
    pNew->lockingContext = zLockFile;
  }

#if OS_VXWORKS
  else if( pLockingStyle == &semIoMethods ){
    /* Named semaphore locking uses the file path so it needs to be
    ** included in the semLockingContext
    */
    unixEnterMutex();
    rc = findLockInfo(pNew, &pNew->pLock, &pNew->pOpen);
    if( (rc==SQLITE_OK) && (pNew->pOpen->pSem==NULL) ){
      char *zSemName = pNew->pOpen->aSemName;
      int n;
      sqlite3_snprintf(MAX_PATHNAME, zSemName, "/%s.sem",
                       pNew->pId->zCanonicalName);
      for( n=1; zSemName[n]; n++ )
        if( zSemName[n]=='/' ) zSemName[n] = '_';
      pNew->pOpen->pSem = sem_open(zSemName, O_CREAT, 0666, 1);
      if( pNew->pOpen->pSem == SEM_FAILED ){
        rc = SQLITE_NOMEM;
        pNew->pOpen->aSemName[0] = '\0';
      }
    }
    unixLeaveMutex();
  }
#endif

  pNew->lastErrno = 0;
#if OS_VXWORKS
  if( rc!=SQLITE_OK ){
    unlink(zFilename);
    isDelete = 0;
  }
  pNew->isDelete = isDelete;
#endif
  if( rc!=SQLITE_OK ){
    if( dirfd>=0 ) close(dirfd); /* silent leak if fail, already in error */
    if( h>=0 ) close(h);
  }else{
    pNew->pMethod = pLockingStyle;
    OpenCounter(+1);
  }
  return rc;
}

/*
** Open a file descriptor to the directory containing file zFilename.
** If successful, *pFd is set to the opened file descriptor and
** SQLITE_OK is returned. If an error occurs, either SQLITE_NOMEM
** or SQLITE_CANTOPEN is returned and *pFd is set to an undefined
** value.
**
** If SQLITE_OK is returned, the caller is responsible for closing
** the file descriptor *pFd using close().
*/
static int openDirectory(const char *zFilename, int *pFd){
  int ii;
  int fd = -1;
  char zDirname[MAX_PATHNAME+1];

  sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename);
  for(ii=(int)strlen(zDirname); ii>1 && zDirname[ii]!='/'; ii--);
  if( ii>0 ){
    zDirname[ii] = '\0';
    fd = open(zDirname, O_RDONLY|O_BINARY, 0);
    if( fd>=0 ){
#ifdef FD_CLOEXEC
      fcntl(fd, F_SETFD, fcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif
      OSTRACE3("OPENDIR %-3d %s\n", fd, zDirname);
    }
  }
  *pFd = fd;
  return (fd>=0?SQLITE_OK:SQLITE_CANTOPEN_BKPT);
}

/*
** Create a temporary file name in zBuf.  zBuf must be allocated
** by the calling process and must be big enough to hold at least
** pVfs->mxPathname bytes.
*/
static int getTempname(int nBuf, char *zBuf){
  static const char *azDirs[] = {
     0,
     0,
     "/var/tmp",
     "/usr/tmp",
     "/tmp",
     ".",
  };
  static const unsigned char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  unsigned int i, j;
  struct stat buf;
  const char *zDir = ".";

  /* It's odd to simulate an io-error here, but really this is just
  ** using the io-error infrastructure to test that SQLite handles this
  ** function failing.
  */
  SimulateIOError( return SQLITE_IOERR );

  azDirs[0] = sqlite3_temp_directory;
  if (NULL == azDirs[1]) {
    azDirs[1] = getenv("TMPDIR");
  }

  for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
    if( azDirs[i]==0 ) continue;
    if( stat(azDirs[i], &buf) ) continue;
    if( !S_ISDIR(buf.st_mode) ) continue;
    if( access(azDirs[i], 07) ) continue;
    zDir = azDirs[i];
    break;
  }

  /* Check that the output buffer is large enough for the temporary file
  ** name. If it is not, return SQLITE_ERROR.
  */
  if( (strlen(zDir) + strlen(SQLITE_TEMP_FILE_PREFIX) + 17) >= (size_t)nBuf ){
    return SQLITE_ERROR;
  }

  do{
    sqlite3_snprintf(nBuf-17, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX, zDir);
    j = (int)strlen(zBuf);
    sqlite3_randomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
  }while( access(zBuf,0)==0 );
  return SQLITE_OK;
}

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
/*
** Routine to transform a unixFile into a proxy-locking unixFile.
** Implementation in the proxy-lock division, but used by unixOpen()
** if SQLITE_PREFER_PROXY_LOCKING is defined.
*/
static int proxyTransformUnixFile(unixFile*, const char*);
#endif

/*
** Search for an unused file descriptor that was opened on the database
** file (not a journal or master-journal file) identified by pathname
** zPath with SQLITE_OPEN_XXX flags matching those passed as the second
** argument to this function.
**
** Such a file descriptor may exist if a database connection was closed
** but the associated file descriptor could not be closed because some
** other file descriptor open on the same file is holding a file-lock.
** Refer to comments in the unixClose() function and the lengthy comment
** describing "Posix Advisory Locking" at the start of this file for
** further details. Also, ticket #4018.
**
** If a suitable file descriptor is found, then it is returned. If no
** such file descriptor is located, -1 is returned.
*/
static UnixUnusedFd *findReusableFd(const char *zPath, int flags){
  UnixUnusedFd *pUnused = 0;

  /* Do not search for an unused file descriptor on vxworks. Not because
  ** vxworks would not benefit from the change (it might, we're not sure),
  ** but because no way to test it is currently available. It is better
  ** not to risk breaking vxworks support for the sake of such an obscure
  ** feature.  */
#if !OS_VXWORKS
  struct stat sStat;                   /* Results of stat() call */

  /* A stat() call may fail for various reasons. If this happens, it is
  ** almost certain that an open() call on the same path will also fail.
  ** For this reason, if an error occurs in the stat() call here, it is
  ** ignored and -1 is returned. The caller will try to open a new file
  ** descriptor on the same path, fail, and return an error to SQLite.
  **
  ** Even if a subsequent open() call does succeed, the consequences of
  ** not searching for a resusable file descriptor are not dire.  */
  if( 0==stat(zPath, &sStat) ){
    struct unixOpenCnt *pOpen;

    unixEnterMutex();
    pOpen = openList;
    while( pOpen && (pOpen->fileId.dev!=sStat.st_dev
                     || pOpen->fileId.ino!=sStat.st_ino) ){
       pOpen = pOpen->pNext;
    }
    if( pOpen ){
      UnixUnusedFd **pp;
      for(pp=&pOpen->pUnused; *pp && (*pp)->flags!=flags; pp=&((*pp)->pNext));
      pUnused = *pp;
      if( pUnused ){
        *pp = pUnused->pNext;
      }
    }
    unixLeaveMutex();
  }
#endif    /* if !OS_VXWORKS */
  return pUnused;
}

/*
** Open the file zPath.
**
** Previously, the SQLite OS layer used three functions in place of this
** one:
**
**     sqlite3OsOpenReadWrite();
**     sqlite3OsOpenReadOnly();
**     sqlite3OsOpenExclusive();
**
** These calls correspond to the following combinations of flags:
**
**     ReadWrite() ->     (READWRITE | CREATE)
**     ReadOnly()  ->     (READONLY)
**     OpenExclusive() -> (READWRITE | CREATE | EXCLUSIVE)
**
** The old OpenExclusive() accepted a boolean argument - "delFlag". If
** true, the file was configured to be automatically deleted when the
** file handle closed. To achieve the same effect using this new
** interface, add the DELETEONCLOSE flag to those specified above for
** OpenExclusive().
*/
static int unixOpen(
  sqlite3_vfs *pVfs,           /* The VFS for which this is the xOpen method */
  const char *zPath,           /* Pathname of file to be opened */
  sqlite3_file *pFile,         /* The file descriptor to be filled in */
  int flags,                   /* Input flags to control the opening */
  int *pOutFlags               /* Output flags returned to SQLite core */
){
  unixFile *p = (unixFile *)pFile;
  int fd = -1;                   /* File descriptor returned by open() */
  int dirfd = -1;                /* Directory file descriptor */
  int openFlags = 0;             /* Flags to pass to open() */
  int eType = flags&0xFFFFFF00;  /* Type of file to open */
  int noLock;                    /* True to omit locking primitives */
  int rc = SQLITE_OK;            /* Function Return Code */

  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
  int isCreate     = (flags & SQLITE_OPEN_CREATE);
  int isReadonly   = (flags & SQLITE_OPEN_READONLY);
  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);

  /* If creating a master or main-file journal, this function will open
  ** a file-descriptor on the directory too. The first time unixSync()
  ** is called the directory file descriptor will be fsync()ed and close()d.
  */
  int isOpenDirectory = (isCreate &&
      (eType==SQLITE_OPEN_MASTER_JOURNAL || eType==SQLITE_OPEN_MAIN_JOURNAL)
  );

  /* If argument zPath is a NULL pointer, this function is required to open
  ** a temporary file. Use this buffer to store the file name in.
  */
  char zTmpname[MAX_PATHNAME+1];
  const char *zName = zPath;

  /* Check the following statements are true:
  **
  **   (a) Exactly one of the READWRITE and READONLY flags must be set, and
  **   (b) if CREATE is set, then READWRITE must also be set, and
  **   (c) if EXCLUSIVE is set, then CREATE must also be set.
  **   (d) if DELETEONCLOSE is set, then CREATE must also be set.
  */
  assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
  assert(isCreate==0 || isReadWrite);
  assert(isExclusive==0 || isCreate);
  assert(isDelete==0 || isCreate);

  /* The main DB, main journal, and master journal are never automatically
  ** deleted. Nor are they ever temporary files.  */
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB );
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL );
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL );

  /* Assert that the upper layer has set one of the "file-type" flags. */
  assert( eType==SQLITE_OPEN_MAIN_DB      || eType==SQLITE_OPEN_TEMP_DB
       || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL
       || eType==SQLITE_OPEN_SUBJOURNAL   || eType==SQLITE_OPEN_MASTER_JOURNAL
       || eType==SQLITE_OPEN_TRANSIENT_DB
  );

  memset(p, 0, sizeof(unixFile));

  if( eType==SQLITE_OPEN_MAIN_DB ){
    UnixUnusedFd *pUnused;
    pUnused = findReusableFd(zName, flags);
    if( pUnused ){
      fd = pUnused->fd;
    }else{
      pUnused = sqlite3_malloc(sizeof(*pUnused));
      if( !pUnused ){
        return SQLITE_NOMEM;
      }
    }
    p->pUnused = pUnused;
  }else if( !zName ){
    /* If zName is NULL, the upper layer is requesting a temp file. */
    assert(isDelete && !isOpenDirectory);
    rc = getTempname(MAX_PATHNAME+1, zTmpname);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    zName = zTmpname;
  }

  /* Determine the value of the flags parameter passed to POSIX function
  ** open(). These must be calculated even if open() is not called, as
  ** they may be stored as part of the file handle and used by the
  ** 'conch file' locking functions later on.  */
  if( isReadonly )  openFlags |= O_RDONLY;
  if( isReadWrite ) openFlags |= O_RDWR;
  if( isCreate )    openFlags |= O_CREAT;
  if( isExclusive ) openFlags |= (O_EXCL|O_NOFOLLOW);
  openFlags |= (O_LARGEFILE|O_BINARY);

  if( fd<0 ){
    mode_t openMode = (isDelete?0600:SQLITE_DEFAULT_FILE_PERMISSIONS);
    fd = open(zName, openFlags, openMode);
    OSTRACE4("OPENX   %-3d %s 0%o\n", fd, zName, openFlags);
    if( fd<0 && errno!=EISDIR && isReadWrite && !isExclusive ){
      /* Failed to open the file for read/write access. Try read-only. */
      flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
      openFlags &= ~(O_RDWR|O_CREAT);
      flags |= SQLITE_OPEN_READONLY;
      openFlags |= O_RDONLY;
      fd = open(zName, openFlags, openMode);
    }
    if( fd<0 ){
      rc = SQLITE_CANTOPEN_BKPT;
      goto open_finished;
    }
  }
  assert( fd>=0 );
  if( pOutFlags ){
    *pOutFlags = flags;
  }

  if( p->pUnused ){
    p->pUnused->fd = fd;
    p->pUnused->flags = flags;
  }

  if( isDelete ){
#if OS_VXWORKS
    zPath = zName;
#else
    unlink(zName);
#endif
  }
#if SQLITE_ENABLE_LOCKING_STYLE
  else{
    p->openFlags = openFlags;
  }
#endif

  if( isOpenDirectory ){
    rc = openDirectory(zPath, &dirfd);
    if( rc!=SQLITE_OK ){
      /* It is safe to close fd at this point, because it is guaranteed not
      ** to be open on a database file. If it were open on a database file,
      ** it would not be safe to close as this would release any locks held
      ** on the file by this process.  */
      assert( eType!=SQLITE_OPEN_MAIN_DB );
      close(fd);             /* silently leak if fail, already in error */
      goto open_finished;
    }
  }

#ifdef FD_CLOEXEC
  fcntl(fd, F_SETFD, fcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif

  noLock = eType!=SQLITE_OPEN_MAIN_DB;

#if SQLITE_PREFER_PROXY_LOCKING
  if( zPath!=NULL && !noLock && pVfs->xOpen ){
    char *envforce = getenv("SQLITE_FORCE_PROXY_LOCKING");
    int useProxy = 0;

    /* SQLITE_FORCE_PROXY_LOCKING==1 means force always use proxy, 0 means
    ** never use proxy, NULL means use proxy for non-local files only.  */
    if( envforce!=NULL ){
      useProxy = atoi(envforce)>0;
    }else{
      struct statfs fsInfo;
      if( statfs(zPath, &fsInfo) == -1 ){
        /* In theory, the close(fd) call is sub-optimal. If the file opened
        ** with fd is a database file, and there are other connections open
        ** on that file that are currently holding advisory locks on it,
        ** then the call to close() will cancel those locks. In practice,
        ** we're assuming that statfs() doesn't fail very often. At least
        ** not while other file descriptors opened by the same process on
        ** the same file are working.  */
        p->lastErrno = errno;
        if( dirfd>=0 ){
          close(dirfd); /* silently leak if fail, in error */
        }
        close(fd); /* silently leak if fail, in error */
        rc = SQLITE_IOERR_ACCESS;
        goto open_finished;
      }
      useProxy = !(fsInfo.f_flags&MNT_LOCAL);
    }
    if( useProxy ){
      rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock, isDelete);
      if( rc==SQLITE_OK ){
        rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:");
      }
      goto open_finished;
    }
  }
#endif

  rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock, isDelete);
open_finished:
  if( rc!=SQLITE_OK ){
    sqlite3_free(p->pUnused);
  }
  return rc;
}


/*
** Delete the file at zPath. If the dirSync argument is true, fsync()
** the directory after deleting the file.
*/
static int unixDelete(
  sqlite3_vfs *NotUsed,     /* VFS containing this as the xDelete method */
  const char *zPath,        /* Name of file to be deleted */
  int dirSync               /* If true, fsync() directory after deleting file */
){
  int rc = SQLITE_OK;
  UNUSED_PARAMETER(NotUsed);
  SimulateIOError(return SQLITE_IOERR_DELETE);
  unlink(zPath);
#ifndef SQLITE_DISABLE_DIRSYNC
  if( dirSync ){
    int fd;
    rc = openDirectory(zPath, &fd);
    if( rc==SQLITE_OK ){
#if OS_VXWORKS
      if( fsync(fd)==-1 )
#else
      if( fsync(fd) )
#endif
      {
        rc = SQLITE_IOERR_DIR_FSYNC;
      }
      if( close(fd)&&!rc ){
        rc = SQLITE_IOERR_DIR_CLOSE;
      }
    }
  }
#endif
  return rc;
}

/*
** Test the existance of or access permissions of file zPath. The
** test performed depends on the value of flags:
**
**     SQLITE_ACCESS_EXISTS: Return 1 if the file exists
**     SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable.
**     SQLITE_ACCESS_READONLY: Return 1 if the file is readable.
**
** Otherwise return 0.
*/
static int unixAccess(
  sqlite3_vfs *NotUsed,   /* The VFS containing this xAccess method */
  const char *zPath,      /* Path of the file to examine */
  int flags,              /* What do we want to learn about the zPath file? */
  int *pResOut            /* Write result boolean here */
){
  int amode = 0;
  UNUSED_PARAMETER(NotUsed);
  SimulateIOError( return SQLITE_IOERR_ACCESS; );
  switch( flags ){
    case SQLITE_ACCESS_EXISTS:
      amode = F_OK;
      break;
    case SQLITE_ACCESS_READWRITE:
      amode = W_OK|R_OK;
      break;
    case SQLITE_ACCESS_READ:
      amode = R_OK;
      break;

    default:
      assert(!"Invalid flags argument");
  }
  *pResOut = (access(zPath, amode)==0);
  return SQLITE_OK;
}


/*
** Turn a relative pathname into a full pathname. The relative path
** is stored as a nul-terminated string in the buffer pointed to by
** zPath.
**
** zOut points to a buffer of at least sqlite3_vfs.mxPathname bytes
** (in this case, MAX_PATHNAME bytes). The full-path is written to
** this buffer before returning.
*/
static int unixFullPathname(
  sqlite3_vfs *pVfs,            /* Pointer to vfs object */
  const char *zPath,            /* Possibly relative input path */
  int nOut,                     /* Size of output buffer in bytes */
  char *zOut                    /* Output buffer */
){

  /* It's odd to simulate an io-error here, but really this is just
  ** using the io-error infrastructure to test that SQLite handles this
  ** function failing. This function could fail if, for example, the
  ** current working directory has been unlinked.
  */
  SimulateIOError( return SQLITE_ERROR );

  assert( pVfs->mxPathname==MAX_PATHNAME );
  UNUSED_PARAMETER(pVfs);

  zOut[nOut-1] = '\0';
  if( zPath[0]=='/' ){
    sqlite3_snprintf(nOut, zOut, "%s", zPath);
  }else{
    int nCwd;
    if( getcwd(zOut, nOut-1)==0 ){
      return SQLITE_CANTOPEN_BKPT;
    }
    nCwd = (int)strlen(zOut);
    sqlite3_snprintf(nOut-nCwd, &zOut[nCwd], "/%s", zPath);
  }
  return SQLITE_OK;
}


#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
#include <dlfcn.h>
static void *unixDlOpen(sqlite3_vfs *NotUsed, const char *zFilename){
  UNUSED_PARAMETER(NotUsed);
  return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL);
}

/*
** SQLite calls this function immediately after a call to unixDlSym() or
** unixDlOpen() fails (returns a null pointer). If a more detailed error
** message is available, it is written to zBufOut. If no error message
** is available, zBufOut is left unmodified and SQLite uses a default
** error message.
*/
static void unixDlError(sqlite3_vfs *NotUsed, int nBuf, char *zBufOut){
  char *zErr;
  UNUSED_PARAMETER(NotUsed);
  unixEnterMutex();
  zErr = dlerror();
  if( zErr ){
    sqlite3_snprintf(nBuf, zBufOut, "%s", zErr);
  }
  unixLeaveMutex();
}
static void (*unixDlSym(sqlite3_vfs *NotUsed, void *p, const char*zSym))(void){
  /*
  ** GCC with -pedantic-errors says that C90 does not allow a void* to be
  ** cast into a pointer to a function.  And yet the library dlsym() routine
  ** returns a void* which is really a pointer to a function.  So how do we
  ** use dlsym() with -pedantic-errors?
  **
  ** Variable x below is defined to be a pointer to a function taking
  ** parameters void* and const char* and returning a pointer to a function.
  ** We initialize x by assigning it a pointer to the dlsym() function.
  ** (That assignment requires a cast.)  Then we call the function that
  ** x points to.
  **
  ** This work-around is unlikely to work correctly on any system where
  ** you really cannot cast a function pointer into void*.  But then, on the
  ** other hand, dlsym() will not work on such a system either, so we have
  ** not really lost anything.
  */
  void (*(*x)(void*,const char*))(void);
  UNUSED_PARAMETER(NotUsed);
  x = (void(*(*)(void*,const char*))(void))dlsym;
  return (*x)(p, zSym);
}
static void unixDlClose(sqlite3_vfs *NotUsed, void *pHandle){
  UNUSED_PARAMETER(NotUsed);
  dlclose(pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
  #define unixDlOpen  0
  #define unixDlError 0
  #define unixDlSym   0
  #define unixDlClose 0
#endif

/*
** Write nBuf bytes of random data to the supplied buffer zBuf.
*/
static int unixRandomness(sqlite3_vfs *NotUsed, int nBuf, char *zBuf){
  UNUSED_PARAMETER(NotUsed);
  assert((size_t)nBuf>=(sizeof(time_t)+sizeof(int)));

  /* We have to initialize zBuf to prevent valgrind from reporting
  ** errors.  The reports issued by valgrind are incorrect - we would
  ** prefer that the randomness be increased by making use of the
  ** uninitialized space in zBuf - but valgrind errors tend to worry
  ** some users.  Rather than argue, it seems easier just to initialize
  ** the whole array and silence valgrind, even if that means less randomness
  ** in the random seed.
  **
  ** When testing, initializing zBuf[] to zero is all we do.  That means
  ** that we always use the same random number sequence.  This makes the
  ** tests repeatable.
  */
  memset(zBuf, 0, nBuf);
#if !defined(SQLITE_TEST)
  {
    int pid, fd;
    fd = open("/dev/urandom", O_RDONLY);
    if( fd<0 ){
      time_t t;
      time(&t);
      memcpy(zBuf, &t, sizeof(t));
      pid = getpid();
      memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid));
      assert( sizeof(t)+sizeof(pid)<=(size_t)nBuf );
      nBuf = sizeof(t) + sizeof(pid);
    }else{
      nBuf = read(fd, zBuf, nBuf);
      close(fd);
    }
  }
#endif
  return nBuf;
}


/*
** Sleep for a little while.  Return the amount of time slept.
** The argument is the number of microseconds we want to sleep.
** The return value is the number of microseconds of sleep actually
** requested from the underlying operating system, a number which
** might be greater than or equal to the argument, but not less
** than the argument.
*/
static int unixSleep(sqlite3_vfs *NotUsed, int microseconds){
#if OS_VXWORKS
  struct timespec sp;

  sp.tv_sec = microseconds / 1000000;
  sp.tv_nsec = (microseconds % 1000000) * 1000;
  nanosleep(&sp, NULL);
  UNUSED_PARAMETER(NotUsed);
  return microseconds;
#elif defined(HAVE_USLEEP) && HAVE_USLEEP
  usleep(microseconds);
  UNUSED_PARAMETER(NotUsed);
  return microseconds;
#else
  int seconds = (microseconds+999999)/1000000;
  sleep(seconds);
  UNUSED_PARAMETER(NotUsed);
  return seconds*1000000;
#endif
}

/*
** The following variable, if set to a non-zero value, is interpreted as
** the number of seconds since 1970 and is used to set the result of
** sqlite3OsCurrentTime() during testing.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_current_time = 0;  /* Fake system time in seconds since 1970. */
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
static int unixCurrentTime(sqlite3_vfs *NotUsed, double *prNow){
#if defined(SQLITE_OMIT_FLOATING_POINT)
  time_t t;
  time(&t);
  *prNow = (((sqlite3_int64)t)/8640 + 24405875)/10;
#elif defined(NO_GETTOD)
  time_t t;
  time(&t);
  *prNow = t/86400.0 + 2440587.5;
#elif OS_VXWORKS
  struct timespec sNow;
  clock_gettime(CLOCK_REALTIME, &sNow);
  *prNow = 2440587.5 + sNow.tv_sec/86400.0 + sNow.tv_nsec/86400000000000.0;
#else
  struct timeval sNow;
  gettimeofday(&sNow, 0);
  *prNow = 2440587.5 + sNow.tv_sec/86400.0 + sNow.tv_usec/86400000000.0;
#endif

#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;
  }
#endif
  UNUSED_PARAMETER(NotUsed);
  return 0;
}

/*
** We added the xGetLastError() method with the intention of providing
** better low-level error messages when operating-system problems come up
** during SQLite operation.  But so far, none of that has been implemented
** in the core.  So this routine is never called.  For now, it is merely
** a place-holder.
*/
static int unixGetLastError(sqlite3_vfs *NotUsed, int NotUsed2, char *NotUsed3){
  UNUSED_PARAMETER(NotUsed);
  UNUSED_PARAMETER(NotUsed2);
  UNUSED_PARAMETER(NotUsed3);
  return 0;
}

/*
************************ End of sqlite3_vfs methods ***************************
******************************************************************************/

/******************************************************************************
************************** Begin Proxy Locking ********************************
**
** Proxy locking is a "uber-locking-method" in this sense:  It uses the
** other locking methods on secondary lock files.  Proxy locking is a
** meta-layer over top of the primitive locking implemented above.  For
** this reason, the division that implements of proxy locking is deferred
** until late in the file (here) after all of the other I/O methods have
** been defined - so that the primitive locking methods are available
** as services to help with the implementation of proxy locking.
**
****
**
** The default locking schemes in SQLite use byte-range locks on the
** database file to coordinate safe, concurrent access by multiple readers
** and writers [http://sqlite.org/lockingv3.html].  The five file locking
** states (UNLOCKED, PENDING, SHARED, RESERVED, EXCLUSIVE) are implemented
** as POSIX read & write locks over fixed set of locations (via fsctl),
** on AFP and SMB only exclusive byte-range locks are available via fsctl
** with _IOWR('z', 23, struct ByteRangeLockPB2) to track the same 5 states.
** To simulate a F_RDLCK on the shared range, on AFP a randomly selected
** address in the shared range is taken for a SHARED lock, the entire
** shared range is taken for an EXCLUSIVE lock):
**
**      PENDING_BYTE        0x40000000
**      RESERVED_BYTE       0x40000001
**      SHARED_RANGE        0x40000002 -> 0x40000200
**
** This works well on the local file system, but shows a nearly 100x
** slowdown in read performance on AFP because the AFP client disables
** the read cache when byte-range locks are present.  Enabling the read
** cache exposes a cache coherency problem that is present on all OS X
** supported network file systems.  NFS and AFP both observe the
** close-to-open semantics for ensuring cache coherency
** [http://nfs.sourceforge.net/#faq_a8], which does not effectively
** address the requirements for concurrent database access by multiple
** readers and writers
** [http://www.nabble.com/SQLite-on-NFS-cache-coherency-td15655701.html].
**
** To address the performance and cache coherency issues, proxy file locking
** changes the way database access is controlled by limiting access to a
** single host at a time and moving file locks off of the database file
** and onto a proxy file on the local file system.
**
**
** Using proxy locks
** -----------------
**
** C APIs
**
**  sqlite3_file_control(db, dbname, SQLITE_SET_LOCKPROXYFILE,
**                       <proxy_path> | ":auto:");
**  sqlite3_file_control(db, dbname, SQLITE_GET_LOCKPROXYFILE, &<proxy_path>);
**
**
** SQL pragmas
**
**  PRAGMA [database.]lock_proxy_file=<proxy_path> | :auto:
**  PRAGMA [database.]lock_proxy_file
**
** Specifying ":auto:" means that if there is a conch file with a matching
** host ID in it, the proxy path in the conch file will be used, otherwise
** a proxy path based on the user's temp dir
** (via confstr(_CS_DARWIN_USER_TEMP_DIR,...)) will be used and the
** actual proxy file name is generated from the name and path of the
** database file.  For example:
**
**       For database path "/Users/me/foo.db"
**       The lock path will be "<tmpdir>/sqliteplocks/_Users_me_foo.db:auto:")
**
** Once a lock proxy is configured for a database connection, it can not
** be removed, however it may be switched to a different proxy path via
** the above APIs (assuming the conch file is not being held by another
** connection or process).
**
**
** How proxy locking works
** -----------------------
**
** Proxy file locking relies primarily on two new supporting files:
**
**   *  conch file to limit access to the database file to a single host
**      at a time
**
**   *  proxy file to act as a proxy for the advisory locks normally
**      taken on the database
**
** The conch file - to use a proxy file, sqlite must first "hold the conch"
** by taking an sqlite-style shared lock on the conch file, reading the
** contents and comparing the host's unique host ID (see below) and lock
** proxy path against the values stored in the conch.  The conch file is
** stored in the same directory as the database file and the file name
** is patterned after the database file name as ".<databasename>-conch".
** If the conch file does not exist, or it's contents do not match the
** host ID and/or proxy path, then the lock is escalated to an exclusive
** lock and the conch file contents is updated with the host ID and proxy
** path and the lock is downgraded to a shared lock again.  If the conch
** is held by another process (with a shared lock), the exclusive lock
** will fail and SQLITE_BUSY is returned.
**
** The proxy file - a single-byte file used for all advisory file locks
** normally taken on the database file.   This allows for safe sharing
** of the database file for multiple readers and writers on the same
** host (the conch ensures that they all use the same local lock file).
**
** There is a third file - the host ID file - used as a persistent record
** of a unique identifier for the host, a 128-byte unique host id file
** in the path defined by the HOSTIDPATH macro (default value is
** /Library/Caches/.com.apple.sqliteConchHostId).
**
** Requesting the lock proxy does not immediately take the conch, it is
** only taken when the first request to lock database file is made.
** This matches the semantics of the traditional locking behavior, where
** opening a connection to a database file does not take a lock on it.
** The shared lock and an open file descriptor are maintained until
** the connection to the database is closed.
**
** The proxy file and the lock file are never deleted so they only need
** to be created the first time they are used.
**
** Configuration options
** ---------------------
**
**  SQLITE_PREFER_PROXY_LOCKING
**
**       Database files accessed on non-local file systems are
**       automatically configured for proxy locking, lock files are
**       named automatically using the same logic as
**       PRAGMA lock_proxy_file=":auto:"
**
**  SQLITE_PROXY_DEBUG
**
**       Enables the logging of error messages during host id file
**       retrieval and creation
**
**  HOSTIDPATH
**
**       Overrides the default host ID file path location
**
**  LOCKPROXYDIR
**
**       Overrides the default directory used for lock proxy files that
**       are named automatically via the ":auto:" setting
**
**  SQLITE_DEFAULT_PROXYDIR_PERMISSIONS
**
**       Permissions to use when creating a directory for storing the
**       lock proxy files, only used when LOCKPROXYDIR is not set.
**
**
** As mentioned above, when compiled with SQLITE_PREFER_PROXY_LOCKING,
** setting the environment variable SQLITE_FORCE_PROXY_LOCKING to 1 will
** force proxy locking to be used for every database file opened, and 0
** will force automatic proxy locking to be disabled for all database
** files (explicity calling the SQLITE_SET_LOCKPROXYFILE pragma or
** sqlite_file_control API is not affected by SQLITE_FORCE_PROXY_LOCKING).
*/

/*
** Proxy locking is only available on MacOSX
*/
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE

#ifdef SQLITE_TEST
/* simulate multiple hosts by creating unique hostid file paths */
SQLITE_API int sqlite3_hostid_num = 0;
#endif

/*
** The proxyLockingContext has the path and file structures for the remote
** and local proxy files in it
*/
typedef struct proxyLockingContext proxyLockingContext;
struct proxyLockingContext {
  unixFile *conchFile;         /* Open conch file */
  char *conchFilePath;         /* Name of the conch file */
  unixFile *lockProxy;         /* Open proxy lock file */
  char *lockProxyPath;         /* Name of the proxy lock file */
  char *dbPath;                /* Name of the open file */
  int conchHeld;               /* True if the conch is currently held */
  void *oldLockingContext;     /* Original lockingcontext to restore on close */
  sqlite3_io_methods const *pOldMethod;     /* Original I/O methods for close */
};

/* HOSTIDLEN and CONCHLEN both include space for the string
** terminating nul
*/
#define HOSTIDLEN         128
#define CONCHLEN          (MAXPATHLEN+HOSTIDLEN+1)
#ifndef HOSTIDPATH
# define HOSTIDPATH       "/Library/Caches/.com.apple.sqliteConchHostId"
#endif

/* basically a copy of unixRandomness with different
** test behavior built in */
static int proxyGenerateHostID(char *pHostID){
  int pid, fd, len;
  unsigned char *key = (unsigned char *)pHostID;

  memset(key, 0, HOSTIDLEN);
  len = 0;
  fd = open("/dev/urandom", O_RDONLY);
  if( fd>=0 ){
    len = read(fd, key, HOSTIDLEN);
    close(fd); /* silently leak the fd if it fails */
  }
  if( len < HOSTIDLEN ){
    time_t t;
    time(&t);
    memcpy(key, &t, sizeof(t));
    pid = getpid();
    memcpy(&key[sizeof(t)], &pid, sizeof(pid));
  }

#ifdef MAKE_PRETTY_HOSTID
  {
    int i;
    /* filter the bytes into printable ascii characters and NUL terminate */
    key[(HOSTIDLEN-1)] = 0x00;
    for( i=0; i<(HOSTIDLEN-1); i++ ){
      unsigned char pa = key[i]&0x7F;
      if( pa<0x20 ){
        key[i] = (key[i]&0x80 == 0x80) ? pa+0x40 : pa+0x20;
      }else if( pa==0x7F ){
        key[i] = (key[i]&0x80 == 0x80) ? pa=0x20 : pa+0x7E;
      }
    }
  }
#endif
  return SQLITE_OK;
}

/* writes the host id path to path, path should be an pre-allocated buffer
** with enough space for a path
*/
static void proxyGetHostIDPath(char *path, size_t len){
  strlcpy(path, HOSTIDPATH, len);
#ifdef SQLITE_TEST
  if( sqlite3_hostid_num>0 ){
    char suffix[2] = "1";
    suffix[0] = suffix[0] + sqlite3_hostid_num;
    strlcat(path, suffix, len);
  }
#endif
  OSTRACE3("GETHOSTIDPATH  %s pid=%d\n", path, getpid());
}

/* get the host ID from a sqlite hostid file stored in the
** user-specific tmp directory, create the ID if it's not there already
*/
static int proxyGetHostID(char *pHostID, int *pError){
  int fd;
  char path[MAXPATHLEN];
  size_t len;
  int rc=SQLITE_OK;

  proxyGetHostIDPath(path, MAXPATHLEN);
  /* try to create the host ID file, if it already exists read the contents */
  fd = open(path, O_CREAT|O_WRONLY|O_EXCL, 0644);
  if( fd<0 ){
    int err=errno;

    if( err!=EEXIST ){
#ifdef SQLITE_PROXY_DEBUG /* set the sqlite error message instead */
      fprintf(stderr, "sqlite error creating host ID file %s: %s\n",
              path, strerror(err));
#endif
      return SQLITE_PERM;
    }
    /* couldn't create the file, read it instead */
    fd = open(path, O_RDONLY|O_EXCL);
    if( fd<0 ){
#ifdef SQLITE_PROXY_DEBUG /* set the sqlite error message instead */
      int err = errno;
      fprintf(stderr, "sqlite error opening host ID file %s: %s\n",
              path, strerror(err));
#endif
      return SQLITE_PERM;
    }
    len = pread(fd, pHostID, HOSTIDLEN, 0);
    if( len<0 ){
      *pError = errno;
      rc = SQLITE_IOERR_READ;
    }else if( len<HOSTIDLEN ){
      *pError = 0;
      rc = SQLITE_IOERR_SHORT_READ;
    }
    close(fd); /* silently leak the fd if it fails */
    OSTRACE3("GETHOSTID  read %s pid=%d\n", pHostID, getpid());
    return rc;
  }else{
    /* we're creating the host ID file (use a random string of bytes) */
    proxyGenerateHostID(pHostID);
    len = pwrite(fd, pHostID, HOSTIDLEN, 0);
    if( len<0 ){
      *pError = errno;
      rc = SQLITE_IOERR_WRITE;
    }else if( len<HOSTIDLEN ){
      *pError = 0;
      rc = SQLITE_IOERR_WRITE;
    }
    close(fd); /* silently leak the fd if it fails */
    OSTRACE3("GETHOSTID  wrote %s pid=%d\n", pHostID, getpid());
    return rc;
  }
}

static int proxyGetLockPath(const char *dbPath, char *lPath, size_t maxLen){
  int len;
  int dbLen;
  int i;

#ifdef LOCKPROXYDIR
  len = strlcpy(lPath, LOCKPROXYDIR, maxLen);
#else
# ifdef _CS_DARWIN_USER_TEMP_DIR
  {
    confstr(_CS_DARWIN_USER_TEMP_DIR, lPath, maxLen);
    len = strlcat(lPath, "sqliteplocks", maxLen);
    if( mkdir(lPath, SQLITE_DEFAULT_PROXYDIR_PERMISSIONS) ){
      /* if mkdir fails, handle as lock file creation failure */
#  ifdef SQLITE_DEBUG
      int err = errno;
      if( err!=EEXIST ){
        fprintf(stderr, "proxyGetLockPath: mkdir(%s,0%o) error %d %s\n", lPath,
                SQLITE_DEFAULT_PROXYDIR_PERMISSIONS, err, strerror(err));
      }
#  endif
    }else{
      OSTRACE3("GETLOCKPATH  mkdir %s pid=%d\n", lPath, getpid());
    }

  }
# else
  len = strlcpy(lPath, "/tmp/", maxLen);
# endif
#endif

  if( lPath[len-1]!='/' ){
    len = strlcat(lPath, "/", maxLen);
  }

  /* transform the db path to a unique cache name */
  dbLen = (int)strlen(dbPath);
  for( i=0; i<dbLen && (i+len+7)<maxLen; i++){
    char c = dbPath[i];
    lPath[i+len] = (c=='/')?'_':c;
  }
  lPath[i+len]='\0';
  strlcat(lPath, ":auto:", maxLen);
  return SQLITE_OK;
}

/*
** Create a new VFS file descriptor (stored in memory obtained from
** sqlite3_malloc) and open the file named "path" in the file descriptor.
**
** The caller is responsible not only for closing the file descriptor
** but also for freeing the memory associated with the file descriptor.
*/
static int proxyCreateUnixFile(const char *path, unixFile **ppFile) {
  unixFile *pNew;
  int flags = SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE;
  int rc = SQLITE_OK;
  sqlite3_vfs dummyVfs;

  pNew = (unixFile *)sqlite3_malloc(sizeof(unixFile));
  if( !pNew ){
    return SQLITE_NOMEM;
  }
  memset(pNew, 0, sizeof(unixFile));

  /* Call unixOpen() to open the proxy file. The flags passed to unixOpen()
  ** suggest that the file being opened is a "main database". This is
  ** necessary as other file types do not necessarily support locking. It
  ** is better to use unixOpen() instead of opening the file directly with
  ** open(), as unixOpen() sets up the various mechanisms required to
  ** make sure a call to close() does not cause the system to discard
  ** POSIX locks prematurely.
  **
  ** It is important that the xOpen member of the VFS object passed to
  ** unixOpen() is NULL. This tells unixOpen() may try to open a proxy-file
  ** for the proxy-file (creating a potential infinite loop).
  */
  pUnused = findReusableFd(path, openFlags);
  if( pUnused ){
    fd = pUnused->fd;
  }else{
    pUnused = sqlite3_malloc(sizeof(*pUnused));
    if( !pUnused ){
      return SQLITE_NOMEM;
    }
  }
  if( fd<0 ){
    fd = open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
    terrno = errno;
    if( fd<0 && errno==ENOENT && islockfile ){
      if( proxyCreateLockPath(path) == SQLITE_OK ){
        fd = open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
      }
    }
  }
  if( fd<0 ){
    openFlags = O_RDONLY;
    fd = open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
    terrno = errno;
  }
  if( fd<0 ){
    if( islockfile ){
      return SQLITE_BUSY;
    }
    switch (terrno) {
      case EACCES:
        return SQLITE_PERM;
      case EIO:
        return SQLITE_IOERR_LOCK; /* even though it is the conch */
      default:
        return SQLITE_CANTOPEN_BKPT;
    }
  }

  pNew = (unixFile *)sqlite3_malloc(sizeof(*pNew));
  if( pNew==NULL ){
    rc = SQLITE_NOMEM;
    goto end_create_proxy;
  }
  memset(pNew, 0, sizeof(unixFile));
  pNew->openFlags = openFlags;
  dummyVfs.pAppData = (void*)&autolockIoFinder;
  dummyVfs.xOpen = 0;
  rc = unixOpen(&dummyVfs, path, (sqlite3_file *)pNew, flags, &flags);
  if( rc==SQLITE_OK && (flags&SQLITE_OPEN_READONLY) ){
    pNew->pMethod->xClose((sqlite3_file *)pNew);
    rc = SQLITE_CANTOPEN;
  }

  if( rc!=SQLITE_OK ){
    sqlite3_free(pNew);
    pNew = 0;
  }

  *ppFile = pNew;
  return rc;
}

/* takes the conch by taking a shared lock and read the contents conch, if
** lockPath is non-NULL, the host ID and lock file path must match.  A NULL
** lockPath means that the lockPath in the conch file will be used if the
** host IDs match, or a new lock path will be generated automatically
** and written to the conch file.
*/
static int proxyTakeConch(unixFile *pFile){
  proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;

  if( pCtx->conchHeld>0 ){
    return SQLITE_OK;
  }else{
    unixFile *conchFile = pCtx->conchFile;
    char testValue[CONCHLEN];
    char conchValue[CONCHLEN];
    char lockPath[MAXPATHLEN];
    char *tLockPath = NULL;
    int rc = SQLITE_OK;
    int readRc = SQLITE_OK;
    int syncPerms = 0;

    OSTRACE4("TAKECONCH  %d for %s pid=%d\n", conchFile->h,
             (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), getpid());

    rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, SHARED_LOCK);
    if( rc==SQLITE_OK ){
      int pError = 0;
      memset(testValue, 0, CONCHLEN); /* conch is fixed size */
      rc = proxyGetHostID(testValue, &pError);
      if( (rc&0xff)==SQLITE_IOERR ){
        pFile->lastErrno = pError;
      }
      if( pCtx->lockProxyPath ){
        strlcpy(&testValue[HOSTIDLEN], pCtx->lockProxyPath, MAXPATHLEN);
      }
    }
    if( rc!=SQLITE_OK ){
      goto end_takeconch;
    }

    readRc = unixRead((sqlite3_file *)conchFile, conchValue, CONCHLEN, 0);
    if( readRc!=SQLITE_IOERR_SHORT_READ ){
      if( readRc!=SQLITE_OK ){
        if( (rc&0xff)==SQLITE_IOERR ){
          pFile->lastErrno = conchFile->lastErrno;
        }
        rc = readRc;
        goto end_takeconch;
      }
      /* if the conch has data compare the contents */
      if( !pCtx->lockProxyPath ){
        /* for auto-named local lock file, just check the host ID and we'll
         ** use the local lock file path that's already in there */
        if( !memcmp(testValue, conchValue, HOSTIDLEN) ){
          tLockPath = (char *)&conchValue[HOSTIDLEN];
          goto end_takeconch;
        }
      }else{
        /* we've got the conch if conchValue matches our path and host ID */
        if( !memcmp(testValue, conchValue, CONCHLEN) ){
          goto end_takeconch;
        }
      }
    }else{
      /* a short read means we're "creating" the conch (even though it could
      ** have been user-intervention), if we acquire the exclusive lock,
      ** we'll try to match the current on-disk permissions of the database
      */
      syncPerms = 1;
    }

    /* either conch was emtpy or didn't match */
    if( !pCtx->lockProxyPath ){
      proxyGetLockPath(pCtx->dbPath, lockPath, MAXPATHLEN);
      tLockPath = lockPath;
      strlcpy(&testValue[HOSTIDLEN], lockPath, MAXPATHLEN);
    }

    /* update conch with host and path (this will fail if other process
     ** has a shared lock already) */
    rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, EXCLUSIVE_LOCK);
    if( rc==SQLITE_OK ){
      rc = unixWrite((sqlite3_file *)conchFile, testValue, CONCHLEN, 0);
      if( rc==SQLITE_OK && syncPerms ){
        struct stat buf;
        int err = fstat(pFile->h, &buf);
        if( err==0 ){
          /* try to match the database file permissions, ignore failure */
#ifndef SQLITE_PROXY_DEBUG
          fchmod(conchFile->h, buf.st_mode);
#else
          if( fchmod(conchFile->h, buf.st_mode)!=0 ){
            int code = errno;
            fprintf(stderr, "fchmod %o FAILED with %d %s\n",
                             buf.st_mode, code, strerror(code));
          } else {
            fprintf(stderr, "fchmod %o SUCCEDED\n",buf.st_mode);
          }
        }else{
          int code = errno;
          fprintf(stderr, "STAT FAILED[%d] with %d %s\n",
                          err, code, strerror(code));
#endif
        }
      }
    }
    conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK);

end_takeconch:
    OSTRACE2("TRANSPROXY: CLOSE  %d\n", pFile->h);
    if( rc==SQLITE_OK && pFile->openFlags ){
      if( pFile->h>=0 ){
#ifdef STRICT_CLOSE_ERROR
        if( close(pFile->h) ){
          pFile->lastErrno = errno;
          return SQLITE_IOERR_CLOSE;
        }
#else
        close(pFile->h); /* silently leak fd if fail */
#endif
      }
      pFile->h = -1;
      int fd = open(pCtx->dbPath, pFile->openFlags,
                    SQLITE_DEFAULT_FILE_PERMISSIONS);
      OSTRACE2("TRANSPROXY: OPEN  %d\n", fd);
      if( fd>=0 ){
        pFile->h = fd;
      }else{
        rc=SQLITE_CANTOPEN; /* SQLITE_BUSY? proxyTakeConch called
                               during locking */
      }
    }
    if( rc==SQLITE_OK && !pCtx->lockProxy ){
      char *path = tLockPath ? tLockPath : pCtx->lockProxyPath;
      /* ACS: Need to make a copy of path sometimes */
      rc = proxyCreateUnixFile(path, &pCtx->lockProxy);
    }
    if( rc==SQLITE_OK ){
      pCtx->conchHeld = 1;

      if( tLockPath ){
        pCtx->lockProxyPath = sqlite3DbStrDup(0, tLockPath);
        if( pCtx->lockProxy->pMethod == &afpIoMethods ){
          ((afpLockingContext *)pCtx->lockProxy->lockingContext)->dbPath =
                     pCtx->lockProxyPath;
        }
      }
>>>>>>> BEGIN MERGE CONFLICT

      /* if the conch isn't writable and doesn't match, we can't take it */
      if( (conchFile->openFlags&O_RDWR) == 0 ){
        rc = SQLITE_BUSY;
        goto end_takeconch;
      }

      /* either the conch didn't match or we need to create a new one */
      if( !pCtx->lockProxyPath ){
        proxyGetLockPath(pCtx->dbPath, lockPath, MAXPATHLEN);
        tempLockPath = lockPath;
        /* create a copy of the lock path _only_ if the conch is taken */
      }

      /* update conch with host and path (this will fail if other process
      ** has a shared lock already), if the host id matches, use the big
      ** stick.
      */
      futimes(conchFile->h, NULL);
      if( hostIdMatch && !createConch ){
        if( conchFile->pLock && conchFile->pLock->cnt>1 ){
          /* We are trying for an exclusive lock but another thread in this
           ** same process is still holding a shared lock. */
          rc = SQLITE_BUSY;
        } else {
          rc = proxyConchLock(pFile, myHostID, EXCLUSIVE_LOCK);
        }
      }else{
        rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, EXCLUSIVE_LOCK);
      }
      if( rc==SQLITE_OK ){
        char writeBuffer[PROXY_MAXCONCHLEN];
        int writeSize = 0;

        writeBuffer[0] = (char)PROXY_CONCHVERSION;
        memcpy(&writeBuffer[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN);
        if( pCtx->lockProxyPath!=NULL ){
          strlcpy(&writeBuffer[PROXY_PATHINDEX], pCtx->lockProxyPath, MAXPATHLEN);
        }else{
          strlcpy(&writeBuffer[PROXY_PATHINDEX], tempLockPath, MAXPATHLEN);
        }
        writeSize = PROXY_PATHINDEX + strlen(&writeBuffer[PROXY_PATHINDEX]);
        ftruncate(conchFile->h, writeSize);
        rc = unixWrite((sqlite3_file *)conchFile, writeBuffer, writeSize, 0);
        fsync(conchFile->h);
        /* If we created a new conch file (not just updated the contents of a
         ** valid conch file), try to match the permissions of the database
         */
        if( rc==SQLITE_OK && createConch ){
          struct stat buf;
          int err = fstat(pFile->h, &buf);
          if( err==0 ){
            mode_t cmode = buf.st_mode&(S_IRUSR|S_IWUSR | S_IRGRP|S_IWGRP |
                                        S_IROTH|S_IWOTH);
            /* try to match the database file R/W permissions, ignore failure */
#ifndef SQLITE_PROXY_DEBUG
            fchmod(conchFile->h, cmode);
#else
            if( fchmod(conchFile->h, cmode)!=0 ){
              int code = errno;
              fprintf(stderr, "fchmod %o FAILED with %d %s\n",
                      cmode, code, strerror(code));
            } else {
              fprintf(stderr, "fchmod %o SUCCEDED\n",cmode);
            }
          }else{
            int code = errno;
            fprintf(stderr, "STAT FAILED[%d] with %d %s\n",
                    err, code, strerror(code));
#endif
          }
        }
      }
      conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK);

    end_takeconch:
      OSTRACE2("TRANSPROXY: CLOSE  %d\n", pFile->h);
      if( rc==SQLITE_OK && pFile->openFlags ){
        if( pFile->h>=0 ){
#ifdef STRICT_CLOSE_ERROR
          if( close(pFile->h) ){
            pFile->lastErrno = errno;
            return SQLITE_IOERR_CLOSE;
          }
#else
          close(pFile->h); /* silently leak fd if fail */
#endif
        }
        pFile->h = -1;
        int fd = open(pCtx->dbPath, pFile->openFlags,
                      SQLITE_DEFAULT_FILE_PERMISSIONS);
        OSTRACE2("TRANSPROXY: OPEN  %d\n", fd);
        if( fd>=0 ){
          pFile->h = fd;
        }else{
          rc=SQLITE_CANTOPEN_BKPT; /* SQLITE_BUSY? proxyTakeConch called
           during locking */
        }
      }
      if( rc==SQLITE_OK && !pCtx->lockProxy ){
        char *path = tempLockPath ? tempLockPath : pCtx->lockProxyPath;
        rc = proxyCreateUnixFile(path, &pCtx->lockProxy, 1);
        if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM && tryOldLockPath ){
          /* we couldn't create the proxy lock file with the old lock file path
           ** so try again via auto-naming
           */
          forceNewLockPath = 1;
          tryOldLockPath = 0;
          continue; /* go back to the do {} while start point, try again */
        }
      }
      if( rc==SQLITE_OK ){
        /* Need to make a copy of path if we extracted the value
         ** from the conch file or the path was allocated on the stack
         */
        if( tempLockPath ){
          pCtx->lockProxyPath = sqlite3DbStrDup(0, tempLockPath);
          if( !pCtx->lockProxyPath ){
            rc = SQLITE_NOMEM;
          }
        }
      }
      if( rc==SQLITE_OK ){
        pCtx->conchHeld = 1;

        if( pCtx->lockProxy->pMethod == &afpIoMethods ){
          afpLockingContext *afpCtx;
          afpCtx = (afpLockingContext *)pCtx->lockProxy->lockingContext;
          afpCtx->dbPath = pCtx->lockProxyPath;
        }
      } else {
        conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
      }
      OSTRACE3("TAKECONCH  %d %s\n", conchFile->h, rc==SQLITE_OK?"ok":"failed");
      return rc;
    } while (1); /* in case we need to retry the :auto: lock file - we should never get here except via the 'continue' call. */
============================
    } else {
      conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
    }
    OSTRACE3("TAKECONCH  %d %s\n", conchFile->h, rc==SQLITE_OK?"ok":"failed");
    return rc;
<<<<<<< END MERGE CONFLICT
  }
}

/*
** If pFile holds a lock on a conch file, then release that lock.
*/
static int proxyReleaseConch(unixFile *pFile){
  int rc;                     /* Subroutine return code */
  proxyLockingContext *pCtx;  /* The locking context for the proxy lock */
  unixFile *conchFile;        /* Name of the conch file */

  pCtx = (proxyLockingContext *)pFile->lockingContext;
  conchFile = pCtx->conchFile;
  OSTRACE4("RELEASECONCH  %d for %s pid=%d\n", conchFile->h,
           (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"),
           getpid());
  pCtx->conchHeld = 0;
  rc = conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
  OSTRACE3("RELEASECONCH  %d %s\n", conchFile->h,
           (rc==SQLITE_OK ? "ok" : "failed"));
  return rc;
}

/*
** Given the name of a database file, compute the name of its conch file.
** Store the conch filename in memory obtained from sqlite3_malloc().
** Make *pConchPath point to the new name.  Return SQLITE_OK on success
** or SQLITE_NOMEM if unable to obtain memory.
**
** The caller is responsible for ensuring that the allocated memory
** space is eventually freed.
**
** *pConchPath is set to NULL if a memory allocation error occurs.
*/
static int proxyCreateConchPathname(char *dbPath, char **pConchPath){
  int i;                        /* Loop counter */
  int len = (int)strlen(dbPath); /* Length of database filename - dbPath */
  char *conchPath;              /* buffer in which to construct conch name */

  /* Allocate space for the conch filename and initialize the name to
  ** the name of the original database file. */
  *pConchPath = conchPath = (char *)sqlite3_malloc(len + 8);
  if( conchPath==0 ){
    return SQLITE_NOMEM;
  }
  memcpy(conchPath, dbPath, len+1);

  /* now insert a "." before the last / character */
  for( i=(len-1); i>=0; i-- ){
    if( conchPath[i]=='/' ){
      i++;
      break;
    }
  }
  conchPath[i]='.';
  while ( i<len ){
    conchPath[i+1]=dbPath[i];
    i++;
  }

  /* append the "-conch" suffix to the file */
  memcpy(&conchPath[i+1], "-conch", 7);
  assert( (int)strlen(conchPath) == len+7 );

  return SQLITE_OK;
}


/* Takes a fully configured proxy locking-style unix file and switches
** the local lock file path
*/
static int switchLockProxyPath(unixFile *pFile, const char *path) {
  proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
  char *oldPath = pCtx->lockProxyPath;
  int rc = SQLITE_OK;

  if( pFile->locktype!=NO_LOCK ){
    return SQLITE_BUSY;
  }

  /* nothing to do if the path is NULL, :auto: or matches the existing path */
  if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ||
    (oldPath && !strncmp(oldPath, path, MAXPATHLEN)) ){
    return SQLITE_OK;
  }else{
    unixFile *lockProxy = pCtx->lockProxy;
    pCtx->lockProxy=NULL;
    pCtx->conchHeld = 0;
    if( lockProxy!=NULL ){
      rc=lockProxy->pMethod->xClose((sqlite3_file *)lockProxy);
      if( rc ) return rc;
      sqlite3_free(lockProxy);
    }
    sqlite3_free(oldPath);
    pCtx->lockProxyPath = sqlite3DbStrDup(0, path);
  }

  return rc;
}

/*
** pFile is a file that has been opened by a prior xOpen call.  dbPath
** is a string buffer at least MAXPATHLEN+1 characters in size.
**
** This routine find the filename associated with pFile and writes it
** int dbPath.
*/
static int proxyGetDbPathForUnixFile(unixFile *pFile, char *dbPath){
#if defined(__APPLE__)
  if( pFile->pMethod == &afpIoMethods ){
    /* afp style keeps a reference to the db path in the filePath field
    ** of the struct */
    assert( (int)strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
    strcpy(dbPath, ((afpLockingContext *)pFile->lockingContext)->dbPath);
  }else
#endif
  if( pFile->pMethod == &dotlockIoMethods ){
    /* dot lock style uses the locking context to store the dot lock
    ** file path */
    int len = strlen((char *)pFile->lockingContext) - strlen(DOTLOCK_SUFFIX);
    memcpy(dbPath, (char *)pFile->lockingContext, len + 1);
  }else{
    /* all other styles use the locking context to store the db file path */
    assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
    strcpy(dbPath, (char *)pFile->lockingContext);
  }
  return SQLITE_OK;
}

/*
** Takes an already filled in unix file and alters it so all file locking
** will be performed on the local proxy lock file.  The following fields
** are preserved in the locking context so that they can be restored and
** the unix structure properly cleaned up at close time:
**  ->lockingContext
**  ->pMethod
*/
static int proxyTransformUnixFile(unixFile *pFile, const char *path) {
  proxyLockingContext *pCtx;
  char dbPath[MAXPATHLEN+1];       /* Name of the database file */
  char *lockPath=NULL;
  int rc = SQLITE_OK;

  if( pFile->locktype!=NO_LOCK ){
    return SQLITE_BUSY;
  }
  proxyGetDbPathForUnixFile(pFile, dbPath);
  if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ){
    lockPath=NULL;
  }else{
    lockPath=(char *)path;
  }

  OSTRACE4("TRANSPROXY  %d for %s pid=%d\n", pFile->h,
           (lockPath ? lockPath : ":auto:"), getpid());

  pCtx = sqlite3_malloc( sizeof(*pCtx) );
  if( pCtx==0 ){
    return SQLITE_NOMEM;
  }
  memset(pCtx, 0, sizeof(*pCtx));

  rc = proxyCreateConchPathname(dbPath, &pCtx->conchFilePath);
  if( rc==SQLITE_OK ){
    rc = proxyCreateUnixFile(pCtx->conchFilePath, &pCtx->conchFile);
  }
  if( rc==SQLITE_OK && lockPath ){
    pCtx->lockProxyPath = sqlite3DbStrDup(0, lockPath);
  }

  if( rc==SQLITE_OK ){
    /* all memory is allocated, proxys are created and assigned,
    ** switch the locking context and pMethod then return.
    */
    pCtx->dbPath = sqlite3DbStrDup(0, dbPath);
    pCtx->oldLockingContext = pFile->lockingContext;
    pFile->lockingContext = pCtx;
    pCtx->pOldMethod = pFile->pMethod;
    pFile->pMethod = &proxyIoMethods;
  }else{
    if( pCtx->conchFile ){
      rc = pCtx->conchFile->pMethod->xClose((sqlite3_file *)pCtx->conchFile);
      if( rc ) return rc;
      sqlite3_free(pCtx->conchFile);
    }
    sqlite3_free(pCtx->conchFilePath);
    sqlite3_free(pCtx);
  }
  OSTRACE3("TRANSPROXY  %d %s\n", pFile->h,
           (rc==SQLITE_OK ? "ok" : "failed"));
  return rc;
}


/*
** This routine handles sqlite3_file_control() calls that are specific
** to proxy locking.
*/
static int proxyFileControl(sqlite3_file *id, int op, void *pArg){
  switch( op ){
    case SQLITE_GET_LOCKPROXYFILE: {
      unixFile *pFile = (unixFile*)id;
      if( pFile->pMethod == &proxyIoMethods ){
        proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
        proxyTakeConch(pFile);
        if( pCtx->lockProxyPath ){
          *(const char **)pArg = pCtx->lockProxyPath;
        }else{
          *(const char **)pArg = ":auto: (not held)";
        }
      } else {
        *(const char **)pArg = NULL;
      }
      return SQLITE_OK;
    }
    case SQLITE_SET_LOCKPROXYFILE: {
      unixFile *pFile = (unixFile*)id;
      int rc = SQLITE_OK;
      int isProxyStyle = (pFile->pMethod == &proxyIoMethods);
      if( pArg==NULL || (const char *)pArg==0 ){
        if( isProxyStyle ){
          /* turn off proxy locking - not supported */
          rc = SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/;
        }else{
          /* turn off proxy locking - already off - NOOP */
          rc = SQLITE_OK;
        }
      }else{
        const char *proxyPath = (const char *)pArg;
        if( isProxyStyle ){
          proxyLockingContext *pCtx =
            (proxyLockingContext*)pFile->lockingContext;
          if( !strcmp(pArg, ":auto:")
           || (pCtx->lockProxyPath &&
               !strncmp(pCtx->lockProxyPath, proxyPath, MAXPATHLEN))
          ){
            rc = SQLITE_OK;
          }else{
            rc = switchLockProxyPath(pFile, proxyPath);
          }
        }else{
          /* turn on proxy file locking */
          rc = proxyTransformUnixFile(pFile, proxyPath);
        }
      }
      return rc;
    }
    default: {
      assert( 0 );  /* The call assures that only valid opcodes are sent */
    }
  }
  /*NOTREACHED*/
  return SQLITE_ERROR;
}

/*
** Within this division (the proxying locking implementation) the procedures
** above this point are all utilities.  The lock-related methods of the
** proxy-locking sqlite3_io_method object follow.
*/


/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int proxyCheckReservedLock(sqlite3_file *id, int *pResOut) {
  unixFile *pFile = (unixFile*)id;
  int rc = proxyTakeConch(pFile);
  if( rc==SQLITE_OK ){
    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
    unixFile *proxy = pCtx->lockProxy;
    return proxy->pMethod->xCheckReservedLock((sqlite3_file*)proxy, pResOut);
  }
  return rc;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
**     (3) PENDING_LOCK
**     (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between.  The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal.  The following chart shows the allowed
** transitions and the inserted intermediate states:
**
**    UNLOCKED -> SHARED
**    SHARED -> RESERVED
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** This routine will only increase a lock.  Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int proxyLock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  int rc = proxyTakeConch(pFile);
  if( rc==SQLITE_OK ){
    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
    unixFile *proxy = pCtx->lockProxy;
    rc = proxy->pMethod->xLock((sqlite3_file*)proxy, locktype);
    pFile->locktype = proxy->locktype;
  }
  return rc;
}


/*
** Lower the locking level on file descriptor pFile to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int proxyUnlock(sqlite3_file *id, int locktype) {
  unixFile *pFile = (unixFile*)id;
  int rc = proxyTakeConch(pFile);
  if( rc==SQLITE_OK ){
    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
    unixFile *proxy = pCtx->lockProxy;
    rc = proxy->pMethod->xUnlock((sqlite3_file*)proxy, locktype);
    pFile->locktype = proxy->locktype;
  }
  return rc;
}

/*
** Close a file that uses proxy locks.
*/
static int proxyClose(sqlite3_file *id) {
  if( id ){
    unixFile *pFile = (unixFile*)id;
    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
    unixFile *lockProxy = pCtx->lockProxy;
    unixFile *conchFile = pCtx->conchFile;
    int rc = SQLITE_OK;

    if( lockProxy ){
      rc = lockProxy->pMethod->xUnlock((sqlite3_file*)lockProxy, NO_LOCK);
      if( rc ) return rc;
      rc = lockProxy->pMethod->xClose((sqlite3_file*)lockProxy);
      if( rc ) return rc;
      sqlite3_free(lockProxy);
      pCtx->lockProxy = 0;
    }
    if( conchFile ){
      if( pCtx->conchHeld ){
        rc = proxyReleaseConch(pFile);
        if( rc ) return rc;
      }
      rc = conchFile->pMethod->xClose((sqlite3_file*)conchFile);
      if( rc ) return rc;
      sqlite3_free(conchFile);
    }
    sqlite3_free(pCtx->lockProxyPath);
    sqlite3_free(pCtx->conchFilePath);
    sqlite3_free(pCtx->dbPath);
    /* restore the original locking context and pMethod then close it */
    pFile->lockingContext = pCtx->oldLockingContext;
    pFile->pMethod = pCtx->pOldMethod;
    sqlite3_free(pCtx);
    return pFile->pMethod->xClose(id);
  }
  return SQLITE_OK;
}



#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
/*
** The proxy locking style is intended for use with AFP filesystems.
** And since AFP is only supported on MacOSX, the proxy locking is also
** restricted to MacOSX.
**
**
******************* End of the proxy lock implementation **********************
******************************************************************************/

/*
** Initialize the operating system interface.
**
** This routine registers all VFS implementations for unix-like operating
** systems.  This routine, and the sqlite3_os_end() routine that follows,
** should be the only routines in this file that are visible from other
** files.
**
** This routine is called once during SQLite initialization and by a
** single thread.  The memory allocation and mutex subsystems have not
** necessarily been initialized when this routine is called, and so they
** should not be used.
*/
SQLITE_API int sqlite3_os_init(void){
  /*
  ** The following macro defines an initializer for an sqlite3_vfs object.
  ** The name of the VFS is NAME.  The pAppData is a pointer to a pointer
  ** to the "finder" function.  (pAppData is a pointer to a pointer because
  ** silly C90 rules prohibit a void* from being cast to a function pointer
  ** and so we have to go through the intermediate pointer to avoid problems
  ** when compiling with -pedantic-errors on GCC.)
  **
  ** The FINDER parameter to this macro is the name of the pointer to the
  ** finder-function.  The finder-function returns a pointer to the
  ** sqlite_io_methods object that implements the desired locking
  ** behaviors.  See the division above that contains the IOMETHODS
  ** macro for addition information on finder-functions.
  **
  ** Most finders simply return a pointer to a fixed sqlite3_io_methods
  ** object.  But the "autolockIoFinder" available on MacOSX does a little
  ** more than that; it looks at the filesystem type that hosts the
  ** database file and tries to choose an locking method appropriate for
  ** that filesystem time.
  */
  #define UNIXVFS(VFSNAME, FINDER) {                        \
    1,                    /* iVersion */                    \
    sizeof(unixFile),     /* szOsFile */                    \
    MAX_PATHNAME,         /* mxPathname */                  \
    0,                    /* pNext */                       \
    VFSNAME,              /* zName */                       \
    (void*)&FINDER,       /* pAppData */                    \
    unixOpen,             /* xOpen */                       \
    unixDelete,           /* xDelete */                     \
    unixAccess,           /* xAccess */                     \
    unixFullPathname,     /* xFullPathname */               \
    unixDlOpen,           /* xDlOpen */                     \
    unixDlError,          /* xDlError */                    \
    unixDlSym,            /* xDlSym */                      \
    unixDlClose,          /* xDlClose */                    \
    unixRandomness,       /* xRandomness */                 \
    unixSleep,            /* xSleep */                      \
    unixCurrentTime,      /* xCurrentTime */                \
    unixGetLastError      /* xGetLastError */               \
  }

  /*
  ** All default VFSes for unix are contained in the following array.
  **
  ** Note that the sqlite3_vfs.pNext field of the VFS object is modified
  ** by the SQLite core when the VFS is registered.  So the following
  ** array cannot be const.
  */
  static sqlite3_vfs aVfs[] = {
#if SQLITE_ENABLE_LOCKING_STYLE && (OS_VXWORKS || defined(__APPLE__))
    UNIXVFS("unix",          autolockIoFinder ),
#else
    UNIXVFS("unix",          posixIoFinder ),
#endif
    UNIXVFS("unix-none",     nolockIoFinder ),
    UNIXVFS("unix-dotfile",  dotlockIoFinder ),
    UNIXVFS("unix-wfl",      posixWflIoFinder ),
#if OS_VXWORKS
    UNIXVFS("unix-namedsem", semIoFinder ),
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
    UNIXVFS("unix-posix",    posixIoFinder ),
#if !OS_VXWORKS
    UNIXVFS("unix-flock",    flockIoFinder ),
#endif
#endif
#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
    UNIXVFS("unix-afp",      afpIoFinder ),
    UNIXVFS("unix-proxy",    proxyIoFinder ),
#endif
  };
  unsigned int i;          /* Loop counter */

  /* Register all VFSes defined in the aVfs[] array */
  for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
    sqlite3_vfs_register(&aVfs[i], i==0);
  }
  return SQLITE_OK;
}

/*
** Shutdown the operating system interface.
**
** Some operating systems might need to do some cleanup in this routine,
** to release dynamically allocated objects.  But not on unix.
** This routine is a no-op for unix.
*/
SQLITE_API int sqlite3_os_end(void){
  return SQLITE_OK;
}

#endif /* SQLITE_OS_UNIX */

/************** End of os_unix.c *********************************************/
/************** Begin file os_win.c ******************************************/
/*
** 2004 May 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains code that is specific to windows.
*/
#if SQLITE_OS_WIN               /* This file is used for windows only */


/*
** A Note About Memory Allocation:
**
** This driver uses malloc()/free() directly rather than going through
** the SQLite-wrappers sqlite3_malloc()/sqlite3_free().  Those wrappers
** are designed for use on embedded systems where memory is scarce and
** malloc failures happen frequently.  Win32 does not typically run on
** embedded systems, and when it does the developers normally have bigger
** problems to worry about than running out of memory.  So there is not
** a compelling need to use the wrappers.
**
** But there is a good reason to not use the wrappers.  If we use the
** wrappers then we will get simulated malloc() failures within this
** driver.  And that causes all kinds of problems for our tests.  We
** could enhance SQLite to deal with simulated malloc failures within
** the OS driver, but the code to deal with those failure would not
** be exercised on Linux (which does not need to malloc() in the driver)
** and so we would have difficulty writing coverage tests for that
** code.  Better to leave the code out, we think.
**
** The point of this discussion is as follows:  When creating a new
** OS layer for an embedded system, if you use this file as an example,
** avoid the use of malloc()/free().  Those routines work ok on windows
** desktops but not so well in embedded systems.
*/

#include <winbase.h>

#ifdef __CYGWIN__
# include <sys/cygwin.h>
#endif

/*
** Macros used to determine whether or not to use threads.
*/
#if defined(THREADSAFE) && THREADSAFE
# define SQLITE_W32_THREADS 1
#endif

/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of os_win.c ****************/
/************** Begin file os_common.h ***************************************/
/*
** 2004 May 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains macros and a little bit of code that is common to
** all of the platform-specific files (os_*.c) and is #included into those
** files.
**
** This file should be #included by the os_*.c files only.  It is not a
** general purpose header file.
*/
#ifndef _OS_COMMON_H_
#define _OS_COMMON_H_

/*
** At least two bugs have slipped in because we changed the MEMORY_DEBUG
** macro to SQLITE_DEBUG and some older makefiles have not yet made the
** switch.  The following code should catch this problem at compile-time.
*/
#ifdef MEMORY_DEBUG
# error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
#endif

#ifdef SQLITE_DEBUG
SQLITE_PRIVATE int sqlite3OSTrace = 0;
#define OSTRACE1(X)         if( sqlite3OSTrace ) sqlite3DebugPrintf(X)
#define OSTRACE2(X,Y)       if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y)
#define OSTRACE3(X,Y,Z)     if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y,Z)
#define OSTRACE4(X,Y,Z,A)   if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y,Z,A)
#define OSTRACE5(X,Y,Z,A,B) if( sqlite3OSTrace ) sqlite3DebugPrintf(X,Y,Z,A,B)
#define OSTRACE6(X,Y,Z,A,B,C) \
    if(sqlite3OSTrace) sqlite3DebugPrintf(X,Y,Z,A,B,C)
#define OSTRACE7(X,Y,Z,A,B,C,D) \
    if(sqlite3OSTrace) sqlite3DebugPrintf(X,Y,Z,A,B,C,D)
#else
#define OSTRACE1(X)
#define OSTRACE2(X,Y)
#define OSTRACE3(X,Y,Z)
#define OSTRACE4(X,Y,Z,A)
#define OSTRACE5(X,Y,Z,A,B)
#define OSTRACE6(X,Y,Z,A,B,C)
#define OSTRACE7(X,Y,Z,A,B,C,D)
#endif

/*
** Macros for performance tracing.  Normally turned off.  Only works
** on i486 hardware.
*/
#ifdef SQLITE_PERFORMANCE_TRACE

/*
** hwtime.h contains inline assembler code for implementing
** high-performance timing routines.
*/
/************** Include hwtime.h in the middle of os_common.h ****************/
/************** Begin file hwtime.h ******************************************/
/*
** 2008 May 27
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file contains inline asm code for retrieving "high-performance"
** counters for x86 class CPUs.
*/
#ifndef _HWTIME_H_
#define _HWTIME_H_

/*
** The following routine only works on pentium-class (or newer) processors.
** It uses the RDTSC opcode to read the cycle count value out of the
** processor and returns that value.  This can be used for high-res
** profiling.
*/
#if (defined(__GNUC__) || defined(_MSC_VER)) && \
      (defined(i386) || defined(__i386__) || defined(_M_IX86))

  #if defined(__GNUC__)

  __inline__ sqlite_uint64 sqlite3Hwtime(void){
     unsigned int lo, hi;
     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
     return (sqlite_uint64)hi << 32 | lo;
  }

  #elif defined(_MSC_VER)

  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
     __asm {
        rdtsc
        ret       ; return value at EDX:EAX
     }
  }

  #endif

#elif (defined(__GNUC__) && defined(__x86_64__))

  __inline__ sqlite_uint64 sqlite3Hwtime(void){
      unsigned long val;
      __asm__ __volatile__ ("rdtsc" : "=A" (val));
      return val;
  }

#elif (defined(__GNUC__) && defined(__ppc__))

  __inline__ sqlite_uint64 sqlite3Hwtime(void){
      unsigned long long retval;
      unsigned long junk;
      __asm__ __volatile__ ("\n\
          1:      mftbu   %1\n\
                  mftb    %L0\n\
                  mftbu   %0\n\
                  cmpw    %0,%1\n\
                  bne     1b"
                  : "=r" (retval), "=r" (junk));
      return retval;
  }

#else

  #error Need implementation of sqlite3Hwtime() for your platform.

  /*
  ** To compile without implementing sqlite3Hwtime() for your platform,
  ** you can remove the above #error and use the following
  ** stub function.  You will lose timing support for many
  ** of the debugging and testing utilities, but it should at
  ** least compile and run.
  */
SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }

#endif

#endif /* !defined(_HWTIME_H_) */

/************** End of hwtime.h **********************************************/
/************** Continuing where we left off in os_common.h ******************/

static sqlite_uint64 g_start;
static sqlite_uint64 g_elapsed;
#define TIMER_START       g_start=sqlite3Hwtime()
#define TIMER_END         g_elapsed=sqlite3Hwtime()-g_start
#define TIMER_ELAPSED     g_elapsed
#else
#define TIMER_START
#define TIMER_END
#define TIMER_ELAPSED     ((sqlite_uint64)0)
#endif

/*
** If we compile with the SQLITE_TEST macro set, then the following block
** of code will give us the ability to simulate a disk I/O error.  This
** is used for testing the I/O recovery logic.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_io_error_hit = 0;            /* Total number of I/O Errors */
SQLITE_API int sqlite3_io_error_hardhit = 0;        /* Number of non-benign errors */
SQLITE_API int sqlite3_io_error_pending = 0;        /* Count down to first I/O error */
SQLITE_API int sqlite3_io_error_persist = 0;        /* True if I/O errors persist */
SQLITE_API int sqlite3_io_error_benign = 0;         /* True if errors are benign */
SQLITE_API int sqlite3_diskfull_pending = 0;
SQLITE_API int sqlite3_diskfull = 0;
#define SimulateIOErrorBenign(X) sqlite3_io_error_benign=(X)
#define SimulateIOError(CODE)  \
  if( (sqlite3_io_error_persist && sqlite3_io_error_hit) \
       || sqlite3_io_error_pending-- == 1 )  \
              { local_ioerr(); CODE; }
static void local_ioerr(){
  IOTRACE(("IOERR\n"));
  sqlite3_io_error_hit++;
  if( !sqlite3_io_error_benign ) sqlite3_io_error_hardhit++;
}
#define SimulateDiskfullError(CODE) \
   if( sqlite3_diskfull_pending ){ \
     if( sqlite3_diskfull_pending == 1 ){ \
       local_ioerr(); \
       sqlite3_diskfull = 1; \
       sqlite3_io_error_hit = 1; \
       CODE; \
     }else{ \
       sqlite3_diskfull_pending--; \
     } \
   }
#else
#define SimulateIOErrorBenign(X)
#define SimulateIOError(A)
#define SimulateDiskfullError(A)
#endif

/*
** When testing, keep a count of the number of open files.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_open_file_count = 0;
#define OpenCounter(X)  sqlite3_open_file_count+=(X)
#else
#define OpenCounter(X)
#endif

#endif /* !defined(_OS_COMMON_H_) */

/************** End of os_common.h *******************************************/
/************** Continuing where we left off in os_win.c *********************/

/*
** Some microsoft compilers lack this definition.
*/
#ifndef INVALID_FILE_ATTRIBUTES
# define INVALID_FILE_ATTRIBUTES ((DWORD)-1)
#endif

/*
** Determine if we are dealing with WindowsCE - which has a much
** reduced API.
*/
#if SQLITE_OS_WINCE
# define AreFileApisANSI() 1
# define FormatMessageW(a,b,c,d,e,f,g) 0
#endif

/*
** WinCE lacks native support for file locking so we have to fake it
** with some code of our own.
*/
#if SQLITE_OS_WINCE
typedef struct winceLock {
  int nReaders;       /* Number of reader locks obtained */
  BOOL bPending;      /* Indicates a pending lock has been obtained */
  BOOL bReserved;     /* Indicates a reserved lock has been obtained */
  BOOL bExclusive;    /* Indicates an exclusive lock has been obtained */
} winceLock;
#endif

/*
** The winFile structure is a subclass of sqlite3_file* specific to the win32
** portability layer.
*/
typedef struct winFile winFile;
struct winFile {
  const sqlite3_io_methods *pMethod;/* Must be first */
  HANDLE h;               /* Handle for accessing the file */
  unsigned char locktype; /* Type of lock currently held on this file */
  short sharedLockByte;   /* Randomly chosen byte used as a shared lock */
  DWORD lastErrno;        /* The Windows errno from the last I/O error */
  DWORD sectorSize;       /* Sector size of the device file is on */
#if SQLITE_OS_WINCE
  WCHAR *zDeleteOnClose;  /* Name of file to delete when closing */
  HANDLE hMutex;          /* Mutex used to control access to shared lock */
  HANDLE hShared;         /* Shared memory segment used for locking */
  winceLock local;        /* Locks obtained by this instance of winFile */
  winceLock *shared;      /* Global shared lock memory for the file  */
#endif
};

/*
** Forward prototypes.
*/
static int getSectorSize(
    sqlite3_vfs *pVfs,
    const char *zRelative     /* UTF-8 file name */
);

/*
** The following variable is (normally) set once and never changes
** thereafter.  It records whether the operating system is Win95
** or WinNT.
**
** 0:   Operating system unknown.
** 1:   Operating system is Win95.
** 2:   Operating system is WinNT.
**
** In order to facilitate testing on a WinNT system, the test fixture
** can manually set this value to 1 to emulate Win98 behavior.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_os_type = 0;
#else
static int sqlite3_os_type = 0;
#endif

/*
** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,
** or WinCE.  Return false (zero) for Win95, Win98, or WinME.
**
** Here is an interesting observation:  Win95, Win98, and WinME lack
** the LockFileEx() API.  But we can still statically link against that
** API as long as we don't call it when running Win95/98/ME.  A call to
** this routine is used to determine if the host is Win95/98/ME or
** WinNT/2K/XP so that we will know whether or not we can safely call
** the LockFileEx() API.
*/
#if SQLITE_OS_WINCE
# define isNT()  (1)
#else
  static int isNT(void){
    if( sqlite3_os_type==0 ){
      OSVERSIONINFO sInfo;
      sInfo.dwOSVersionInfoSize = sizeof(sInfo);
      GetVersionEx(&sInfo);
      sqlite3_os_type = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
    }
    return sqlite3_os_type==2;
  }
#endif /* SQLITE_OS_WINCE */

/*
** Convert a UTF-8 string to microsoft unicode (UTF-16?).
**
** Space to hold the returned string is obtained from malloc.
*/
static WCHAR *utf8ToUnicode(const char *zFilename){
  int nChar;
  WCHAR *zWideFilename;

  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, NULL, 0);
  zWideFilename = malloc( nChar*sizeof(zWideFilename[0]) );
  if( zWideFilename==0 ){
    return 0;
  }
  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, zWideFilename, nChar);
  if( nChar==0 ){
    free(zWideFilename);
    zWideFilename = 0;
  }
  return zWideFilename;
}

/*
** Convert microsoft unicode to UTF-8.  Space to hold the returned string is
** obtained from malloc().
*/
static char *unicodeToUtf8(const WCHAR *zWideFilename){
  int nByte;
  char *zFilename;

  nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, 0, 0, 0, 0);
  zFilename = malloc( nByte );
  if( zFilename==0 ){
    return 0;
  }
  nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, zFilename, nByte,
                              0, 0);
  if( nByte == 0 ){
    free(zFilename);
    zFilename = 0;
  }
  return zFilename;
}

/*
** Convert an ansi string to microsoft unicode, based on the
** current codepage settings for file apis.
**
** Space to hold the returned string is obtained
** from malloc.
*/
static WCHAR *mbcsToUnicode(const char *zFilename){
  int nByte;
  WCHAR *zMbcsFilename;
  int codepage = AreFileApisANSI() ? CP_ACP : CP_OEMCP;

  nByte = MultiByteToWideChar(codepage, 0, zFilename, -1, NULL,0)*sizeof(WCHAR);
  zMbcsFilename = malloc( nByte*sizeof(zMbcsFilename[0]) );
  if( zMbcsFilename==0 ){
    return 0;
  }
  nByte = MultiByteToWideChar(codepage, 0, zFilename, -1, zMbcsFilename, nByte);
  if( nByte==0 ){
    free(zMbcsFilename);
    zMbcsFilename = 0;
  }
  return zMbcsFilename;
}

/*
** Convert microsoft unicode to multibyte character string, based on the
** user's Ansi codepage.
**
** Space to hold the returned string is obtained from
** malloc().
*/
static char *unicodeToMbcs(const WCHAR *zWideFilename){
  int nByte;
  char *zFilename;
  int codepage = AreFileApisANSI() ? CP_ACP : CP_OEMCP;

  nByte = WideCharToMultiByte(codepage, 0, zWideFilename, -1, 0, 0, 0, 0);
  zFilename = malloc( nByte );
  if( zFilename==0 ){
    return 0;
  }
  nByte = WideCharToMultiByte(codepage, 0, zWideFilename, -1, zFilename, nByte,
                              0, 0);
  if( nByte == 0 ){
    free(zFilename);
    zFilename = 0;
  }
  return zFilename;
}

/*
** Convert multibyte character string to UTF-8.  Space to hold the
** returned string is obtained from malloc().
*/
SQLITE_API char *sqlite3_win32_mbcs_to_utf8(const char *zFilename){
  char *zFilenameUtf8;
  WCHAR *zTmpWide;

  zTmpWide = mbcsToUnicode(zFilename);
  if( zTmpWide==0 ){
    return 0;
  }
  zFilenameUtf8 = unicodeToUtf8(zTmpWide);
  free(zTmpWide);
  return zFilenameUtf8;
}

/*
** Convert UTF-8 to multibyte character string.  Space to hold the
** returned string is obtained from malloc().
*/
static char *utf8ToMbcs(const char *zFilename){
  char *zFilenameMbcs;
  WCHAR *zTmpWide;

  zTmpWide = utf8ToUnicode(zFilename);
  if( zTmpWide==0 ){
    return 0;
  }
  zFilenameMbcs = unicodeToMbcs(zTmpWide);
  free(zTmpWide);
  return zFilenameMbcs;
}

#if SQLITE_OS_WINCE
/*************************************************************************
** This section contains code for WinCE only.
*/
/*
** WindowsCE does not have a localtime() function.  So create a
** substitute.
*/
struct tm *__cdecl localtime(const time_t *t)
{
  static struct tm y;
  FILETIME uTm, lTm;
  SYSTEMTIME pTm;
  sqlite3_int64 t64;
  t64 = *t;
  t64 = (t64 + 11644473600)*10000000;
  uTm.dwLowDateTime = (DWORD)(t64 & 0xFFFFFFFF);
  uTm.dwHighDateTime= (DWORD)(t64 >> 32);
  FileTimeToLocalFileTime(&uTm,&lTm);
  FileTimeToSystemTime(&lTm,&pTm);
  y.tm_year = pTm.wYear - 1900;
  y.tm_mon = pTm.wMonth - 1;
  y.tm_wday = pTm.wDayOfWeek;
  y.tm_mday = pTm.wDay;
  y.tm_hour = pTm.wHour;
  y.tm_min = pTm.wMinute;
  y.tm_sec = pTm.wSecond;
  return &y;
}

/* This will never be called, but defined to make the code compile */
#define GetTempPathA(a,b)

#define LockFile(a,b,c,d,e)       winceLockFile(&a, b, c, d, e)
#define UnlockFile(a,b,c,d,e)     winceUnlockFile(&a, b, c, d, e)
#define LockFileEx(a,b,c,d,e,f)   winceLockFileEx(&a, b, c, d, e, f)

#define HANDLE_TO_WINFILE(a) (winFile*)&((char*)a)[-(int)offsetof(winFile,h)]

/*
** Acquire a lock on the handle h
*/
static void winceMutexAcquire(HANDLE h){
   DWORD dwErr;
   do {
     dwErr = WaitForSingleObject(h, INFINITE);
   } while (dwErr != WAIT_OBJECT_0 && dwErr != WAIT_ABANDONED);
}
/*
** Release a lock acquired by winceMutexAcquire()
*/
#define winceMutexRelease(h) ReleaseMutex(h)

/*
** Create the mutex and shared memory used for locking in the file
** descriptor pFile
*/
static BOOL winceCreateLock(const char *zFilename, winFile *pFile){
  WCHAR *zTok;
  WCHAR *zName = utf8ToUnicode(zFilename);
  BOOL bInit = TRUE;

  /* Initialize the local lockdata */
  ZeroMemory(&pFile->local, sizeof(pFile->local));

  /* Replace the backslashes from the filename and lowercase it
  ** to derive a mutex name. */
  zTok = CharLowerW(zName);
  for (;*zTok;zTok++){
    if (*zTok == '\\') *zTok = '_';
  }

  /* Create/open the named mutex */
  pFile->hMutex = CreateMutexW(NULL, FALSE, zName);
  if (!pFile->hMutex){
    pFile->lastErrno = GetLastError();
    free(zName);
    return FALSE;
  }

  /* Acquire the mutex before continuing */
  winceMutexAcquire(pFile->hMutex);

  /* Since the names of named mutexes, semaphores, file mappings etc are
  ** case-sensitive, take advantage of that by uppercasing the mutex name
  ** and using that as the shared filemapping name.
  */
  CharUpperW(zName);
  pFile->hShared = CreateFileMappingW(INVALID_HANDLE_VALUE, NULL,
                                       PAGE_READWRITE, 0, sizeof(winceLock),
                                       zName);

  /* Set a flag that indicates we're the first to create the memory so it
  ** must be zero-initialized */
  if (GetLastError() == ERROR_ALREADY_EXISTS){
    bInit = FALSE;
  }

  free(zName);

  /* If we succeeded in making the shared memory handle, map it. */
  if (pFile->hShared){
    pFile->shared = (winceLock*)MapViewOfFile(pFile->hShared,
             FILE_MAP_READ|FILE_MAP_WRITE, 0, 0, sizeof(winceLock));
    /* If mapping failed, close the shared memory handle and erase it */
    if (!pFile->shared){
      pFile->lastErrno = GetLastError();
      CloseHandle(pFile->hShared);
      pFile->hShared = NULL;
    }
  }

  /* If shared memory could not be created, then close the mutex and fail */
  if (pFile->hShared == NULL){
    winceMutexRelease(pFile->hMutex);
    CloseHandle(pFile->hMutex);
    pFile->hMutex = NULL;
    return FALSE;
  }

  /* Initialize the shared memory if we're supposed to */
  if (bInit) {
    ZeroMemory(pFile->shared, sizeof(winceLock));
  }

  winceMutexRelease(pFile->hMutex);
  return TRUE;
}

/*
** Destroy the part of winFile that deals with wince locks
*/
static void winceDestroyLock(winFile *pFile){
  if (pFile->hMutex){
    /* Acquire the mutex */
    winceMutexAcquire(pFile->hMutex);

    /* The following blocks should probably assert in debug mode, but they
       are to cleanup in case any locks remained open */
    if (pFile->local.nReaders){
      pFile->shared->nReaders --;
    }
    if (pFile->local.bReserved){
      pFile->shared->bReserved = FALSE;
    }
    if (pFile->local.bPending){
      pFile->shared->bPending = FALSE;
    }
    if (pFile->local.bExclusive){
      pFile->shared->bExclusive = FALSE;
    }

    /* De-reference and close our copy of the shared memory handle */
    UnmapViewOfFile(pFile->shared);
    CloseHandle(pFile->hShared);

    /* Done with the mutex */
    winceMutexRelease(pFile->hMutex);
    CloseHandle(pFile->hMutex);
    pFile->hMutex = NULL;
  }
}

/*
** An implementation of the LockFile() API of windows for wince
*/
static BOOL winceLockFile(
  HANDLE *phFile,
  DWORD dwFileOffsetLow,
  DWORD dwFileOffsetHigh,
  DWORD nNumberOfBytesToLockLow,
  DWORD nNumberOfBytesToLockHigh
){
  winFile *pFile = HANDLE_TO_WINFILE(phFile);
  BOOL bReturn = FALSE;

  UNUSED_PARAMETER(dwFileOffsetHigh);
  UNUSED_PARAMETER(nNumberOfBytesToLockHigh);

  if (!pFile->hMutex) return TRUE;
  winceMutexAcquire(pFile->hMutex);

  /* Wanting an exclusive lock? */
  if (dwFileOffsetLow == (DWORD)SHARED_FIRST
       && nNumberOfBytesToLockLow == (DWORD)SHARED_SIZE){
    if (pFile->shared->nReaders == 0 && pFile->shared->bExclusive == 0){
       pFile->shared->bExclusive = TRUE;
       pFile->local.bExclusive = TRUE;
       bReturn = TRUE;
    }
  }

  /* Want a read-only lock? */
  else if (dwFileOffsetLow == (DWORD)SHARED_FIRST &&
           nNumberOfBytesToLockLow == 1){
    if (pFile->shared->bExclusive == 0){
      pFile->local.nReaders ++;
      if (pFile->local.nReaders == 1){
        pFile->shared->nReaders ++;
      }
      bReturn = TRUE;
    }
  }

  /* Want a pending lock? */
  else if (dwFileOffsetLow == (DWORD)PENDING_BYTE && nNumberOfBytesToLockLow == 1){
    /* If no pending lock has been acquired, then acquire it */
    if (pFile->shared->bPending == 0) {
      pFile->shared->bPending = TRUE;
      pFile->local.bPending = TRUE;
      bReturn = TRUE;
    }
  }

  /* Want a reserved lock? */
  else if (dwFileOffsetLow == (DWORD)RESERVED_BYTE && nNumberOfBytesToLockLow == 1){
    if (pFile->shared->bReserved == 0) {
      pFile->shared->bReserved = TRUE;
      pFile->local.bReserved = TRUE;
      bReturn = TRUE;
    }
  }

  winceMutexRelease(pFile->hMutex);
  return bReturn;
}

/*
** An implementation of the UnlockFile API of windows for wince
*/
static BOOL winceUnlockFile(
  HANDLE *phFile,
  DWORD dwFileOffsetLow,
  DWORD dwFileOffsetHigh,
  DWORD nNumberOfBytesToUnlockLow,
  DWORD nNumberOfBytesToUnlockHigh
){
  winFile *pFile = HANDLE_TO_WINFILE(phFile);
  BOOL bReturn = FALSE;

  UNUSED_PARAMETER(dwFileOffsetHigh);
  UNUSED_PARAMETER(nNumberOfBytesToUnlockHigh);

  if (!pFile->hMutex) return TRUE;
  winceMutexAcquire(pFile->hMutex);

  /* Releasing a reader lock or an exclusive lock */
  if (dwFileOffsetLow == (DWORD)SHARED_FIRST){
    /* Did we have an exclusive lock? */
    if (pFile->local.bExclusive){
      assert(nNumberOfBytesToUnlockLow == (DWORD)SHARED_SIZE);
      pFile->local.bExclusive = FALSE;
      pFile->shared->bExclusive = FALSE;
      bReturn = TRUE;
    }

    /* Did we just have a reader lock? */
    else if (pFile->local.nReaders){
      assert(nNumberOfBytesToUnlockLow == (DWORD)SHARED_SIZE || nNumberOfBytesToUnlockLow == 1);
      pFile->local.nReaders --;
      if (pFile->local.nReaders == 0)
      {
        pFile->shared->nReaders --;
      }
      bReturn = TRUE;
    }
  }

  /* Releasing a pending lock */
  else if (dwFileOffsetLow == (DWORD)PENDING_BYTE && nNumberOfBytesToUnlockLow == 1){
    if (pFile->local.bPending){
      pFile->local.bPending = FALSE;
      pFile->shared->bPending = FALSE;
      bReturn = TRUE;
    }
  }
  /* Releasing a reserved lock */
  else if (dwFileOffsetLow == (DWORD)RESERVED_BYTE && nNumberOfBytesToUnlockLow == 1){
    if (pFile->local.bReserved) {
      pFile->local.bReserved = FALSE;
      pFile->shared->bReserved = FALSE;
      bReturn = TRUE;
    }
  }

  winceMutexRelease(pFile->hMutex);
  return bReturn;
}

/*
** An implementation of the LockFileEx() API of windows for wince
*/
static BOOL winceLockFileEx(
  HANDLE *phFile,
  DWORD dwFlags,
  DWORD dwReserved,
  DWORD nNumberOfBytesToLockLow,
  DWORD nNumberOfBytesToLockHigh,
  LPOVERLAPPED lpOverlapped
){
  UNUSED_PARAMETER(dwReserved);
  UNUSED_PARAMETER(nNumberOfBytesToLockHigh);

  /* If the caller wants a shared read lock, forward this call
  ** to winceLockFile */
  if (lpOverlapped->Offset == (DWORD)SHARED_FIRST &&
      dwFlags == 1 &&
      nNumberOfBytesToLockLow == (DWORD)SHARED_SIZE){
    return winceLockFile(phFile, SHARED_FIRST, 0, 1, 0);
  }
  return FALSE;
}
/*
** End of the special code for wince
*****************************************************************************/
#endif /* SQLITE_OS_WINCE */

/*****************************************************************************
** The next group of routines implement the I/O methods specified
** by the sqlite3_io_methods object.
******************************************************************************/

/*
** Close a file.
**
** It is reported that an attempt to close a handle might sometimes
** fail.  This is a very unreasonable result, but windows is notorious
** for being unreasonable so I do not doubt that it might happen.  If
** the close fails, we pause for 100 milliseconds and try again.  As
** many as MX_CLOSE_ATTEMPT attempts to close the handle are made before
** giving up and returning an error.
*/
#define MX_CLOSE_ATTEMPT 3
static int winClose(sqlite3_file *id){
  int rc, cnt = 0;
  winFile *pFile = (winFile*)id;

  assert( id!=0 );
  OSTRACE2("CLOSE %d\n", pFile->h);
  do{
    rc = CloseHandle(pFile->h);
  }while( rc==0 && ++cnt < MX_CLOSE_ATTEMPT && (Sleep(100), 1) );
#if SQLITE_OS_WINCE
#define WINCE_DELETION_ATTEMPTS 3
  winceDestroyLock(pFile);
  if( pFile->zDeleteOnClose ){
    int cnt = 0;
    while(
           DeleteFileW(pFile->zDeleteOnClose)==0
        && GetFileAttributesW(pFile->zDeleteOnClose)!=0xffffffff
        && cnt++ < WINCE_DELETION_ATTEMPTS
    ){
       Sleep(100);  /* Wait a little before trying again */
    }
    free(pFile->zDeleteOnClose);
  }
#endif
  OpenCounter(-1);
  return rc ? SQLITE_OK : SQLITE_IOERR;
}

/*
** Some microsoft compilers lack this definition.
*/
#ifndef INVALID_SET_FILE_POINTER
# define INVALID_SET_FILE_POINTER ((DWORD)-1)
#endif

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
*/
static int winRead(
  sqlite3_file *id,          /* File to read from */
  void *pBuf,                /* Write content into this buffer */
  int amt,                   /* Number of bytes to read */
  sqlite3_int64 offset       /* Begin reading at this offset */
){
  LONG upperBits = (LONG)((offset>>32) & 0x7fffffff);
  LONG lowerBits = (LONG)(offset & 0xffffffff);
  DWORD rc;
  winFile *pFile = (winFile*)id;
  DWORD error;
  DWORD got;

  assert( id!=0 );
  SimulateIOError(return SQLITE_IOERR_READ);
  OSTRACE3("READ %d lock=%d\n", pFile->h, pFile->locktype);
  rc = SetFilePointer(pFile->h, lowerBits, &upperBits, FILE_BEGIN);
  if( rc==INVALID_SET_FILE_POINTER && (error=GetLastError())!=NO_ERROR ){
    pFile->lastErrno = error;
    return SQLITE_FULL;
  }
  if( !ReadFile(pFile->h, pBuf, amt, &got, 0) ){
    pFile->lastErrno = GetLastError();
    return SQLITE_IOERR_READ;
  }
  if( got==(DWORD)amt ){
    return SQLITE_OK;
  }else{
    /* Unread parts of the buffer must be zero-filled */
    memset(&((char*)pBuf)[got], 0, amt-got);
    return SQLITE_IOERR_SHORT_READ;
  }
}

/*
** Write data from a buffer into a file.  Return SQLITE_OK on success
** or some other error code on failure.
*/
static int winWrite(
  sqlite3_file *id,         /* File to write into */
  const void *pBuf,         /* The bytes to be written */
  int amt,                  /* Number of bytes to write */
  sqlite3_int64 offset      /* Offset into the file to begin writing at */
){
  LONG upperBits = (LONG)((offset>>32) & 0x7fffffff);
  LONG lowerBits = (LONG)(offset & 0xffffffff);
  DWORD rc;
  winFile *pFile = (winFile*)id;
  DWORD error;
  DWORD wrote = 0;

  assert( id!=0 );
  SimulateIOError(return SQLITE_IOERR_WRITE);
  SimulateDiskfullError(return SQLITE_FULL);
  OSTRACE3("WRITE %d lock=%d\n", pFile->h, pFile->locktype);
  rc = SetFilePointer(pFile->h, lowerBits, &upperBits, FILE_BEGIN);
  if( rc==INVALID_SET_FILE_POINTER && (error=GetLastError())!=NO_ERROR ){
    pFile->lastErrno = error;
    return SQLITE_FULL;
  }
  assert( amt>0 );
  while(
     amt>0
     && (rc = WriteFile(pFile->h, pBuf, amt, &wrote, 0))!=0
     && wrote>0
  ){
    amt -= wrote;
    pBuf = &((char*)pBuf)[wrote];
  }
  if( !rc || amt>(int)wrote ){
    pFile->lastErrno = GetLastError();
    return SQLITE_FULL;
  }
  return SQLITE_OK;
}

/*
** Truncate an open file to a specified size
*/
static int winTruncate(sqlite3_file *id, sqlite3_int64 nByte){
  LONG upperBits = (LONG)((nByte>>32) & 0x7fffffff);
  LONG lowerBits = (LONG)(nByte & 0xffffffff);
  DWORD rc;
  winFile *pFile = (winFile*)id;
  DWORD error;

  assert( id!=0 );
  OSTRACE3("TRUNCATE %d %lld\n", pFile->h, nByte);
  SimulateIOError(return SQLITE_IOERR_TRUNCATE);
  rc = SetFilePointer(pFile->h, lowerBits, &upperBits, FILE_BEGIN);
  if( rc==INVALID_SET_FILE_POINTER && (error=GetLastError())!=NO_ERROR ){
    pFile->lastErrno = error;
    return SQLITE_IOERR_TRUNCATE;
  }
  /* SetEndOfFile will fail if nByte is negative */
  if( !SetEndOfFile(pFile->h) ){
    pFile->lastErrno = GetLastError();
    return SQLITE_IOERR_TRUNCATE;
  }
  return SQLITE_OK;
}

#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs.  This is used to test
** that syncs and fullsyncs are occuring at the right times.
*/
SQLITE_API int sqlite3_sync_count = 0;
SQLITE_API int sqlite3_fullsync_count = 0;
#endif

/*
** Make sure all writes to a particular file are committed to disk.
*/
static int winSync(sqlite3_file *id, int flags){
#ifndef SQLITE_NO_SYNC
  winFile *pFile = (winFile*)id;

  assert( id!=0 );
  OSTRACE3("SYNC %d lock=%d\n", pFile->h, pFile->locktype);
#else
  UNUSED_PARAMETER(id);
#endif
#ifndef SQLITE_TEST
  UNUSED_PARAMETER(flags);
#else
  if( flags & SQLITE_SYNC_FULL ){
    sqlite3_fullsync_count++;
  }
  sqlite3_sync_count++;
#endif
  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
  ** no-op
  */
#ifdef SQLITE_NO_SYNC
    return SQLITE_OK;
#else
  if( FlushFileBuffers(pFile->h) ){
    return SQLITE_OK;
  }else{
    pFile->lastErrno = GetLastError();
    return SQLITE_IOERR;
  }
#endif
}

/*
** Determine the current size of a file in bytes
*/
static int winFileSize(sqlite3_file *id, sqlite3_int64 *pSize){
  DWORD upperBits;
  DWORD lowerBits;
  winFile *pFile = (winFile*)id;
  DWORD error;

  assert( id!=0 );
  SimulateIOError(return SQLITE_IOERR_FSTAT);
  lowerBits = GetFileSize(pFile->h, &upperBits);
  if(   (lowerBits == INVALID_FILE_SIZE)
     && ((error = GetLastError()) != NO_ERROR) )
  {
    pFile->lastErrno = error;
    return SQLITE_IOERR_FSTAT;
  }
  *pSize = (((sqlite3_int64)upperBits)<<32) + lowerBits;
  return SQLITE_OK;
}

/*
** LOCKFILE_FAIL_IMMEDIATELY is undefined on some Windows systems.
*/
#ifndef LOCKFILE_FAIL_IMMEDIATELY
# define LOCKFILE_FAIL_IMMEDIATELY 1
#endif

/*
** Acquire a reader lock.
** Different API routines are called depending on whether or not this
** is Win95 or WinNT.
*/
static int getReadLock(winFile *pFile){
  int res;
  if( isNT() ){
    OVERLAPPED ovlp;
    ovlp.Offset = SHARED_FIRST;
    ovlp.OffsetHigh = 0;
    ovlp.hEvent = 0;
    res = LockFileEx(pFile->h, LOCKFILE_FAIL_IMMEDIATELY,
                     0, SHARED_SIZE, 0, &ovlp);
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
*/
#if SQLITE_OS_WINCE==0
  }else{
    int lk;
    sqlite3_randomness(sizeof(lk), &lk);
    pFile->sharedLockByte = (short)((lk & 0x7fffffff)%(SHARED_SIZE - 1));
    res = LockFile(pFile->h, SHARED_FIRST+pFile->sharedLockByte, 0, 1, 0);
#endif
  }
  if( res == 0 ){
    pFile->lastErrno = GetLastError();
  }
  return res;
}

/*
** Undo a readlock
*/
static int unlockReadLock(winFile *pFile){
  int res;
  if( isNT() ){
    res = UnlockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
*/
#if SQLITE_OS_WINCE==0
  }else{
    res = UnlockFile(pFile->h, SHARED_FIRST + pFile->sharedLockByte, 0, 1, 0);
#endif
  }
  if( res == 0 ){
    pFile->lastErrno = GetLastError();
  }
  return res;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
**     (3) PENDING_LOCK
**     (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between.  The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal.  The following chart shows the allowed
** transitions and the inserted intermediate states:
**
**    UNLOCKED -> SHARED
**    SHARED -> RESERVED
**    SHARED -> (PENDING) -> EXCLUSIVE
**    RESERVED -> (PENDING) -> EXCLUSIVE
**    PENDING -> EXCLUSIVE
**
** This routine will only increase a lock.  The winUnlock() routine
** erases all locks at once and returns us immediately to locking level 0.
** It is not possible to lower the locking level one step at a time.  You
** must go straight to locking level 0.
*/
static int winLock(sqlite3_file *id, int locktype){
  int rc = SQLITE_OK;    /* Return code from subroutines */
  int res = 1;           /* Result of a windows lock call */
  int newLocktype;       /* Set pFile->locktype to this value before exiting */
  int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */
  winFile *pFile = (winFile*)id;
  DWORD error = NO_ERROR;

  assert( id!=0 );
  OSTRACE5("LOCK %d %d was %d(%d)\n",
          pFile->h, locktype, pFile->locktype, pFile->sharedLockByte);

  /* If there is already a lock of this type or more restrictive on the
  ** OsFile, do nothing. Don't use the end_lock: exit path, as
  ** sqlite3OsEnterMutex() hasn't been called yet.
  */
  if( pFile->locktype>=locktype ){
    return SQLITE_OK;
  }

  /* Make sure the locking sequence is correct
  */
  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
  assert( locktype!=PENDING_LOCK );
  assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );

  /* Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or
  ** a SHARED lock.  If we are acquiring a SHARED lock, the acquisition of
  ** the PENDING_LOCK byte is temporary.
  */
  newLocktype = pFile->locktype;
  if(   (pFile->locktype==NO_LOCK)
     || (   (locktype==EXCLUSIVE_LOCK)
         && (pFile->locktype==RESERVED_LOCK))
  ){
    int cnt = 3;
    while( cnt-->0 && (res = LockFile(pFile->h, PENDING_BYTE, 0, 1, 0))==0 ){
      /* Try 3 times to get the pending lock.  The pending lock might be
      ** held by another reader process who will release it momentarily.
      */
      OSTRACE2("could not get a PENDING lock. cnt=%d\n", cnt);
      Sleep(1);
    }
    gotPendingLock = res;
    if( !res ){
      error = GetLastError();
    }
  }

  /* Acquire a shared lock
  */
  if( locktype==SHARED_LOCK && res ){
    assert( pFile->locktype==NO_LOCK );
    res = getReadLock(pFile);
    if( res ){
      newLocktype = SHARED_LOCK;
    }else{
      error = GetLastError();
    }
  }

  /* Acquire a RESERVED lock
  */
  if( locktype==RESERVED_LOCK && res ){
    assert( pFile->locktype==SHARED_LOCK );
    res = LockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
    if( res ){
      newLocktype = RESERVED_LOCK;
    }else{
      error = GetLastError();
    }
  }

  /* Acquire a PENDING lock
  */
  if( locktype==EXCLUSIVE_LOCK && res ){
    newLocktype = PENDING_LOCK;
    gotPendingLock = 0;
  }

  /* Acquire an EXCLUSIVE lock
  */
  if( locktype==EXCLUSIVE_LOCK && res ){
    assert( pFile->locktype>=SHARED_LOCK );
    res = unlockReadLock(pFile);
    OSTRACE2("unreadlock = %d\n", res);
    res = LockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
    if( res ){
      newLocktype = EXCLUSIVE_LOCK;
    }else{
      error = GetLastError();
      OSTRACE2("error-code = %d\n", error);
      getReadLock(pFile);
    }
  }

  /* If we are holding a PENDING lock that ought to be released, then
  ** release it now.
  */
  if( gotPendingLock && locktype==SHARED_LOCK ){
    UnlockFile(pFile->h, PENDING_BYTE, 0, 1, 0);
  }

  /* Update the state of the lock has held in the file descriptor then
  ** return the appropriate result code.
  */
  if( res ){
    rc = SQLITE_OK;
  }else{
    OSTRACE4("LOCK FAILED %d trying for %d but got %d\n", pFile->h,
           locktype, newLocktype);
    pFile->lastErrno = error;
    rc = SQLITE_BUSY;
  }
  pFile->locktype = (u8)newLocktype;
  return rc;
}

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero, otherwise zero.
*/
static int winCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc;
  winFile *pFile = (winFile*)id;

  assert( id!=0 );
  if( pFile->locktype>=RESERVED_LOCK ){
    rc = 1;
    OSTRACE3("TEST WR-LOCK %d %d (local)\n", pFile->h, rc);
  }else{
    rc = LockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
    if( rc ){
      UnlockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
    }
    rc = !rc;
    OSTRACE3("TEST WR-LOCK %d %d (remote)\n", pFile->h, rc);
  }
  *pResOut = rc;
  return SQLITE_OK;
}

/*
** Lower the locking level on file descriptor id to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** It is not possible for this routine to fail if the second argument
** is NO_LOCK.  If the second argument is SHARED_LOCK then this routine
** might return SQLITE_IOERR;
*/
static int winUnlock(sqlite3_file *id, int locktype){
  int type;
  winFile *pFile = (winFile*)id;
  int rc = SQLITE_OK;
  assert( pFile!=0 );
  assert( locktype<=SHARED_LOCK );
  OSTRACE5("UNLOCK %d to %d was %d(%d)\n", pFile->h, locktype,
          pFile->locktype, pFile->sharedLockByte);
  type = pFile->locktype;
  if( type>=EXCLUSIVE_LOCK ){
    UnlockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
    if( locktype==SHARED_LOCK && !getReadLock(pFile) ){
      /* This should never happen.  We should always be able to
      ** reacquire the read lock */
      rc = SQLITE_IOERR_UNLOCK;
    }
  }
  if( type>=RESERVED_LOCK ){
    UnlockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
  }
  if( locktype==NO_LOCK && type>=SHARED_LOCK ){
    unlockReadLock(pFile);
  }
  if( type>=PENDING_LOCK ){
    UnlockFile(pFile->h, PENDING_BYTE, 0, 1, 0);
  }
  pFile->locktype = (u8)locktype;
  return rc;
}

/*
** Control and query of the open file handle.
*/
static int winFileControl(sqlite3_file *id, int op, void *pArg){
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = ((winFile*)id)->locktype;
      return SQLITE_OK;
    }
    case SQLITE_LAST_ERRNO: {
      *(int*)pArg = (int)((winFile*)id)->lastErrno;
      return SQLITE_OK;
    }
  }
  return SQLITE_ERROR;
}

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
** larger for some devices.
**
** SQLite code assumes this function cannot fail. It also assumes that
** if two files are created in the same file-system directory (i.e.
** a database and its journal file) that the sector size will be the
** same for both.
*/
static int winSectorSize(sqlite3_file *id){
  assert( id!=0 );
  return (int)(((winFile*)id)->sectorSize);
}

/*
** Return a vector of device characteristics.
*/
static int winDeviceCharacteristics(sqlite3_file *id){
  UNUSED_PARAMETER(id);
  return 0;
}

/*
** This vector defines all the methods that can operate on an
** sqlite3_file for win32.
*/
static const sqlite3_io_methods winIoMethod = {
  1,                        /* iVersion */
  winClose,
  winRead,
  winWrite,
  winTruncate,
  winSync,
  winFileSize,
  winLock,
  winUnlock,
  winCheckReservedLock,
  winFileControl,
  winSectorSize,
  winDeviceCharacteristics
};

/***************************************************************************
** Here ends the I/O methods that form the sqlite3_io_methods object.
**
** The next block of code implements the VFS methods.
****************************************************************************/

/*
** Convert a UTF-8 filename into whatever form the underlying
** operating system wants filenames in.  Space to hold the result
** is obtained from malloc and must be freed by the calling
** function.
*/
static void *convertUtf8Filename(const char *zFilename){
  void *zConverted = 0;
  if( isNT() ){
    zConverted = utf8ToUnicode(zFilename);
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
*/
#if SQLITE_OS_WINCE==0
  }else{
    zConverted = utf8ToMbcs(zFilename);
#endif
  }
  /* caller will handle out of memory */
  return zConverted;
}

/*
** Create a temporary file name in zBuf.  zBuf must be big enough to
** hold at pVfs->mxPathname characters.
*/
static int getTempname(int nBuf, char *zBuf){
  static char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  size_t i, j;
  char zTempPath[MAX_PATH+1];
  if( sqlite3_temp_directory ){
    sqlite3_snprintf(MAX_PATH-30, zTempPath, "%s", sqlite3_temp_directory);
  }else if( isNT() ){
    char *zMulti;
    WCHAR zWidePath[MAX_PATH];
    GetTempPathW(MAX_PATH-30, zWidePath);
    zMulti = unicodeToUtf8(zWidePath);
    if( zMulti ){
      sqlite3_snprintf(MAX_PATH-30, zTempPath, "%s", zMulti);
      free(zMulti);
    }else{
      return SQLITE_NOMEM;
    }
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
** Since the ASCII version of these Windows API do not exist for WINCE,
** it's important to not reference them for WINCE builds.
*/
#if SQLITE_OS_WINCE==0
  }else{
    char *zUtf8;
    char zMbcsPath[MAX_PATH];
    GetTempPathA(MAX_PATH-30, zMbcsPath);
    zUtf8 = sqlite3_win32_mbcs_to_utf8(zMbcsPath);
    if( zUtf8 ){
      sqlite3_snprintf(MAX_PATH-30, zTempPath, "%s", zUtf8);
      free(zUtf8);
    }else{
      return SQLITE_NOMEM;
    }
#endif
  }
  for(i=sqlite3Strlen30(zTempPath); i>0 && zTempPath[i-1]=='\\'; i--){}
  zTempPath[i] = 0;
  sqlite3_snprintf(nBuf-30, zBuf,
                   "%s\\"SQLITE_TEMP_FILE_PREFIX, zTempPath);
  j = sqlite3Strlen30(zBuf);
  sqlite3_randomness(20, &zBuf[j]);
  for(i=0; i<20; i++, j++){
    zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
  }
  zBuf[j] = 0;
  OSTRACE2("TEMP FILENAME: %s\n", zBuf);
  return SQLITE_OK;
}

/*
** The return value of getLastErrorMsg
** is zero if the error message fits in the buffer, or non-zero
** otherwise (if the message was truncated).
*/
static int getLastErrorMsg(int nBuf, char *zBuf){
  /* FormatMessage returns 0 on failure.  Otherwise it
  ** returns the number of TCHARs written to the output
  ** buffer, excluding the terminating null char.
  */
  DWORD error = GetLastError();
  DWORD dwLen = 0;
  char *zOut = 0;

  if( isNT() ){
    WCHAR *zTempWide = NULL;
    dwLen = FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                           NULL,
                           error,
                           0,
                           (LPWSTR) &zTempWide,
                           0,
                           0);
    if( dwLen > 0 ){
      /* allocate a buffer and convert to UTF8 */
      zOut = unicodeToUtf8(zTempWide);
      /* free the system buffer allocated by FormatMessage */
      LocalFree(zTempWide);
    }
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
** Since the ASCII version of these Windows API do not exist for WINCE,
** it's important to not reference them for WINCE builds.
*/
#if SQLITE_OS_WINCE==0
  }else{
    char *zTemp = NULL;
    dwLen = FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                           NULL,
                           error,
                           0,
                           (LPSTR) &zTemp,
                           0,
                           0);
    if( dwLen > 0 ){
      /* allocate a buffer and convert to UTF8 */
      zOut = sqlite3_win32_mbcs_to_utf8(zTemp);
      /* free the system buffer allocated by FormatMessage */
      LocalFree(zTemp);
    }
#endif
  }
  if( 0 == dwLen ){
    sqlite3_snprintf(nBuf, zBuf, "OsError 0x%x (%u)", error, error);
  }else{
    /* copy a maximum of nBuf chars to output buffer */
    sqlite3_snprintf(nBuf, zBuf, "%s", zOut);
    /* free the UTF8 buffer */
    free(zOut);
  }
  return 0;
}

/*
** Open a file.
*/
static int winOpen(
  sqlite3_vfs *pVfs,        /* Not used */
  const char *zName,        /* Name of the file (UTF-8) */
  sqlite3_file *id,         /* Write the SQLite file handle here */
  int flags,                /* Open mode flags */
  int *pOutFlags            /* Status return flags */
){
  HANDLE h;
  DWORD dwDesiredAccess;
  DWORD dwShareMode;
  DWORD dwCreationDisposition;
  DWORD dwFlagsAndAttributes = 0;
#if SQLITE_OS_WINCE
  int isTemp = 0;
#endif
  winFile *pFile = (winFile*)id;
  void *zConverted;                 /* Filename in OS encoding */
  const char *zUtf8Name = zName;    /* Filename in UTF-8 encoding */
  char zTmpname[MAX_PATH+1];        /* Buffer used to create temp filename */

  assert( id!=0 );
  UNUSED_PARAMETER(pVfs);

  /* If the second argument to this function is NULL, generate a
  ** temporary file name to use
  */
  if( !zUtf8Name ){
    int rc = getTempname(MAX_PATH+1, zTmpname);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    zUtf8Name = zTmpname;
  }

  /* Convert the filename to the system encoding. */
  zConverted = convertUtf8Filename(zUtf8Name);
  if( zConverted==0 ){
    return SQLITE_NOMEM;
  }

  if( flags & SQLITE_OPEN_READWRITE ){
    dwDesiredAccess = GENERIC_READ | GENERIC_WRITE;
  }else{
    dwDesiredAccess = GENERIC_READ;
  }
  /* SQLITE_OPEN_EXCLUSIVE is used to make sure that a new file is
  ** created. SQLite doesn't use it to indicate "exclusive access"
  ** as it is usually understood.
  */
  assert(!(flags & SQLITE_OPEN_EXCLUSIVE) || (flags & SQLITE_OPEN_CREATE));
  if( flags & SQLITE_OPEN_EXCLUSIVE ){
    /* Creates a new file, only if it does not already exist. */
    /* If the file exists, it fails. */
    dwCreationDisposition = CREATE_NEW;
  }else if( flags & SQLITE_OPEN_CREATE ){
    /* Open existing file, or create if it doesn't exist */
    dwCreationDisposition = OPEN_ALWAYS;
  }else{
    /* Opens a file, only if it exists. */
    dwCreationDisposition = OPEN_EXISTING;
  }
  dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
  if( flags & SQLITE_OPEN_DELETEONCLOSE ){
#if SQLITE_OS_WINCE
    dwFlagsAndAttributes = FILE_ATTRIBUTE_HIDDEN;
    isTemp = 1;
#else
    dwFlagsAndAttributes = FILE_ATTRIBUTE_TEMPORARY
                               | FILE_ATTRIBUTE_HIDDEN
                               | FILE_FLAG_DELETE_ON_CLOSE;
#endif
  }else{
    dwFlagsAndAttributes = FILE_ATTRIBUTE_NORMAL;
  }
  /* Reports from the internet are that performance is always
  ** better if FILE_FLAG_RANDOM_ACCESS is used.  Ticket #2699. */
#if SQLITE_OS_WINCE
  dwFlagsAndAttributes |= FILE_FLAG_RANDOM_ACCESS;
#endif
  if( isNT() ){
    h = CreateFileW((WCHAR*)zConverted,
       dwDesiredAccess,
       dwShareMode,
       NULL,
       dwCreationDisposition,
       dwFlagsAndAttributes,
       NULL
    );
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
** Since the ASCII version of these Windows API do not exist for WINCE,
** it's important to not reference them for WINCE builds.
*/
#if SQLITE_OS_WINCE==0
  }else{
    h = CreateFileA((char*)zConverted,
       dwDesiredAccess,
       dwShareMode,
       NULL,
       dwCreationDisposition,
       dwFlagsAndAttributes,
       NULL
    );
#endif
  }
  if( h==INVALID_HANDLE_VALUE ){
    free(zConverted);
    if( flags & SQLITE_OPEN_READWRITE ){
      return winOpen(pVfs, zName, id,
             ((flags|SQLITE_OPEN_READONLY)&~SQLITE_OPEN_READWRITE), pOutFlags);
    }else{
      return SQLITE_CANTOPEN_BKPT;
    }
  }
  if( pOutFlags ){
    if( flags & SQLITE_OPEN_READWRITE ){
      *pOutFlags = SQLITE_OPEN_READWRITE;
    }else{
      *pOutFlags = SQLITE_OPEN_READONLY;
    }
  }
  memset(pFile, 0, sizeof(*pFile));
  pFile->pMethod = &winIoMethod;
  pFile->h = h;
  pFile->lastErrno = NO_ERROR;
  pFile->sectorSize = getSectorSize(pVfs, zUtf8Name);
#if SQLITE_OS_WINCE
  if( (flags & (SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_DB)) ==
               (SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_DB)
       && !winceCreateLock(zName, pFile)
  ){
    CloseHandle(h);
    free(zConverted);
    return SQLITE_CANTOPEN_BKPT;
  }
  if( isTemp ){
    pFile->zDeleteOnClose = zConverted;
  }else
#endif
  {
    free(zConverted);
  }
  OpenCounter(+1);
  return SQLITE_OK;
}

/*
** Delete the named file.
**
** Note that windows does not allow a file to be deleted if some other
** process has it open.  Sometimes a virus scanner or indexing program
** will open a journal file shortly after it is created in order to do
** whatever it does.  While this other process is holding the
** file open, we will be unable to delete it.  To work around this
** problem, we delay 100 milliseconds and try to delete again.  Up
** to MX_DELETION_ATTEMPTs deletion attempts are run before giving
** up and returning an error.
*/
#define MX_DELETION_ATTEMPTS 5
static int winDelete(
  sqlite3_vfs *pVfs,          /* Not used on win32 */
  const char *zFilename,      /* Name of file to delete */
  int syncDir                 /* Not used on win32 */
){
  int cnt = 0;
  DWORD rc;
  DWORD error = 0;
  void *zConverted = convertUtf8Filename(zFilename);
  UNUSED_PARAMETER(pVfs);
  UNUSED_PARAMETER(syncDir);
  if( zConverted==0 ){
    return SQLITE_NOMEM;
  }
  SimulateIOError(return SQLITE_IOERR_DELETE);
  if( isNT() ){
    do{
      DeleteFileW(zConverted);
    }while(   (   ((rc = GetFileAttributesW(zConverted)) != INVALID_FILE_ATTRIBUTES)
               || ((error = GetLastError()) == ERROR_ACCESS_DENIED))
           && (++cnt < MX_DELETION_ATTEMPTS)
           && (Sleep(100), 1) );
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
** Since the ASCII version of these Windows API do not exist for WINCE,
** it's important to not reference them for WINCE builds.
*/
#if SQLITE_OS_WINCE==0
  }else{
    do{
      DeleteFileA(zConverted);
    }while(   (   ((rc = GetFileAttributesA(zConverted)) != INVALID_FILE_ATTRIBUTES)
               || ((error = GetLastError()) == ERROR_ACCESS_DENIED))
           && (++cnt < MX_DELETION_ATTEMPTS)
           && (Sleep(100), 1) );
#endif
  }
  free(zConverted);
  OSTRACE2("DELETE \"%s\"\n", zFilename);
  return (   (rc == INVALID_FILE_ATTRIBUTES)
          && (error == ERROR_FILE_NOT_FOUND)) ? SQLITE_OK : SQLITE_IOERR_DELETE;
}

/*
** Check the existance and status of a file.
*/
static int winAccess(
  sqlite3_vfs *pVfs,         /* Not used on win32 */
  const char *zFilename,     /* Name of file to check */
  int flags,                 /* Type of test to make on this file */
  int *pResOut               /* OUT: Result */
){
  DWORD attr;
  int rc = 0;
  void *zConverted = convertUtf8Filename(zFilename);
  UNUSED_PARAMETER(pVfs);
  if( zConverted==0 ){
    return SQLITE_NOMEM;
  }
  if( isNT() ){
    attr = GetFileAttributesW((WCHAR*)zConverted);
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
** Since the ASCII version of these Windows API do not exist for WINCE,
** it's important to not reference them for WINCE builds.
*/
#if SQLITE_OS_WINCE==0
  }else{
    attr = GetFileAttributesA((char*)zConverted);
#endif
  }
  free(zConverted);
  switch( flags ){
    case SQLITE_ACCESS_READ:
    case SQLITE_ACCESS_EXISTS:
      rc = attr!=INVALID_FILE_ATTRIBUTES;
      break;
    case SQLITE_ACCESS_READWRITE:
      rc = (attr & FILE_ATTRIBUTE_READONLY)==0;
      break;
    default:
      assert(!"Invalid flags argument");
  }
  *pResOut = rc;
  return SQLITE_OK;
}


/*
** Turn a relative pathname into a full pathname.  Write the full
** pathname into zOut[].  zOut[] will be at least pVfs->mxPathname
** bytes in size.
*/
static int winFullPathname(
  sqlite3_vfs *pVfs,            /* Pointer to vfs object */
  const char *zRelative,        /* Possibly relative input path */
  int nFull,                    /* Size of output buffer in bytes */
  char *zFull                   /* Output buffer */
){

#if defined(__CYGWIN__)
  UNUSED_PARAMETER(nFull);
  cygwin_conv_to_full_win32_path(zRelative, zFull);
  return SQLITE_OK;
#endif

#if SQLITE_OS_WINCE
  UNUSED_PARAMETER(nFull);
  /* WinCE has no concept of a relative pathname, or so I am told. */
  sqlite3_snprintf(pVfs->mxPathname, zFull, "%s", zRelative);
  return SQLITE_OK;
#endif

#if !SQLITE_OS_WINCE && !defined(__CYGWIN__)
  int nByte;
  void *zConverted;
  char *zOut;
  UNUSED_PARAMETER(nFull);
  zConverted = convertUtf8Filename(zRelative);
  if( isNT() ){
    WCHAR *zTemp;
    nByte = GetFullPathNameW((WCHAR*)zConverted, 0, 0, 0) + 3;
    zTemp = malloc( nByte*sizeof(zTemp[0]) );
    if( zTemp==0 ){
      free(zConverted);
      return SQLITE_NOMEM;
    }
    GetFullPathNameW((WCHAR*)zConverted, nByte, zTemp, 0);
    free(zConverted);
    zOut = unicodeToUtf8(zTemp);
    free(zTemp);
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
** Since the ASCII version of these Windows API do not exist for WINCE,
** it's important to not reference them for WINCE builds.
*/
#if SQLITE_OS_WINCE==0
  }else{
    char *zTemp;
    nByte = GetFullPathNameA((char*)zConverted, 0, 0, 0) + 3;
    zTemp = malloc( nByte*sizeof(zTemp[0]) );
    if( zTemp==0 ){
      free(zConverted);
      return SQLITE_NOMEM;
    }
    GetFullPathNameA((char*)zConverted, nByte, zTemp, 0);
    free(zConverted);
    zOut = sqlite3_win32_mbcs_to_utf8(zTemp);
    free(zTemp);
#endif
  }
  if( zOut ){
    sqlite3_snprintf(pVfs->mxPathname, zFull, "%s", zOut);
    free(zOut);
    return SQLITE_OK;
  }else{
    return SQLITE_NOMEM;
  }
#endif
}

/*
** Get the sector size of the device used to store
** file.
*/
static int getSectorSize(
    sqlite3_vfs *pVfs,
    const char *zRelative     /* UTF-8 file name */
){
  DWORD bytesPerSector = SQLITE_DEFAULT_SECTOR_SIZE;
  /* GetDiskFreeSpace is not supported under WINCE */
#if SQLITE_OS_WINCE
  UNUSED_PARAMETER(pVfs);
  UNUSED_PARAMETER(zRelative);
#else
  char zFullpath[MAX_PATH+1];
  int rc;
  DWORD dwRet = 0;
  DWORD dwDummy;

  /*
  ** We need to get the full path name of the file
  ** to get the drive letter to look up the sector
  ** size.
  */
  rc = winFullPathname(pVfs, zRelative, MAX_PATH, zFullpath);
  if( rc == SQLITE_OK )
  {
    void *zConverted = convertUtf8Filename(zFullpath);
    if( zConverted ){
      if( isNT() ){
        /* trim path to just drive reference */
        WCHAR *p = zConverted;
        for(;*p;p++){
          if( *p == '\\' ){
            *p = '\0';
            break;
          }
        }
        dwRet = GetDiskFreeSpaceW((WCHAR*)zConverted,
                                  &dwDummy,
                                  &bytesPerSector,
                                  &dwDummy,
                                  &dwDummy);
      }else{
        /* trim path to just drive reference */
        char *p = (char *)zConverted;
        for(;*p;p++){
          if( *p == '\\' ){
            *p = '\0';
            break;
          }
        }
        dwRet = GetDiskFreeSpaceA((char*)zConverted,
                                  &dwDummy,
                                  &bytesPerSector,
                                  &dwDummy,
                                  &dwDummy);
      }
      free(zConverted);
    }
    if( !dwRet ){
      bytesPerSector = SQLITE_DEFAULT_SECTOR_SIZE;
    }
  }
#endif
  return (int) bytesPerSector;
}

#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
static void *winDlOpen(sqlite3_vfs *pVfs, const char *zFilename){
  HANDLE h;
  void *zConverted = convertUtf8Filename(zFilename);
  UNUSED_PARAMETER(pVfs);
  if( zConverted==0 ){
    return 0;
  }
  if( isNT() ){
    h = LoadLibraryW((WCHAR*)zConverted);
/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed.
** Since the ASCII version of these Windows API do not exist for WINCE,
** it's important to not reference them for WINCE builds.
*/
#if SQLITE_OS_WINCE==0
  }else{
    h = LoadLibraryA((char*)zConverted);
#endif
  }
  free(zConverted);
  return (void*)h;
}
static void winDlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){
  UNUSED_PARAMETER(pVfs);
  getLastErrorMsg(nBuf, zBufOut);
}
void (*winDlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol))(void){
  UNUSED_PARAMETER(pVfs);
#if SQLITE_OS_WINCE
  /* The GetProcAddressA() routine is only available on wince. */
  return (void(*)(void))GetProcAddressA((HANDLE)pHandle, zSymbol);
#else
  /* All other windows platforms expect GetProcAddress() to take
  ** an Ansi string regardless of the _UNICODE setting */
  return (void(*)(void))GetProcAddress((HANDLE)pHandle, zSymbol);
#endif
}
void winDlClose(sqlite3_vfs *pVfs, void *pHandle){
  UNUSED_PARAMETER(pVfs);
  FreeLibrary((HANDLE)pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
  #define winDlOpen  0
  #define winDlError 0
  #define winDlSym   0
  #define winDlClose 0
#endif


/*
** Write up to nBuf bytes of randomness into zBuf.
*/
static int winRandomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
  int n = 0;
  UNUSED_PARAMETER(pVfs);
#if defined(SQLITE_TEST)
  n = nBuf;
  memset(zBuf, 0, nBuf);
#else
  if( sizeof(SYSTEMTIME)<=nBuf-n ){
    SYSTEMTIME x;
    GetSystemTime(&x);
    memcpy(&zBuf[n], &x, sizeof(x));
    n += sizeof(x);
  }
  if( sizeof(DWORD)<=nBuf-n ){
    DWORD pid = GetCurrentProcessId();
    memcpy(&zBuf[n], &pid, sizeof(pid));
    n += sizeof(pid);
  }
  if( sizeof(DWORD)<=nBuf-n ){
    DWORD cnt = GetTickCount();
    memcpy(&zBuf[n], &cnt, sizeof(cnt));
    n += sizeof(cnt);
  }
  if( sizeof(LARGE_INTEGER)<=nBuf-n ){
    LARGE_INTEGER i;
    QueryPerformanceCounter(&i);
    memcpy(&zBuf[n], &i, sizeof(i));
    n += sizeof(i);
  }
#endif
  return n;
}


/*
** Sleep for a little while.  Return the amount of time slept.
*/
static int winSleep(sqlite3_vfs *pVfs, int microsec){
  Sleep((microsec+999)/1000);
  UNUSED_PARAMETER(pVfs);
  return ((microsec+999)/1000)*1000;
}

/*
** The following variable, if set to a non-zero value, becomes the result
** returned from sqlite3OsCurrentTime().  This is used for testing.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_current_time = 0;
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
int winCurrentTime(sqlite3_vfs *pVfs, double *prNow){
  FILETIME ft;
  /* FILETIME structure is a 64-bit value representing the number of
     100-nanosecond intervals since January 1, 1601 (= JD 2305813.5).
  */
  sqlite3_int64 timeW;   /* Whole days */
  sqlite3_int64 timeF;   /* Fractional Days */

  /* Number of 100-nanosecond intervals in a single day */
  static const sqlite3_int64 ntuPerDay =
      10000000*(sqlite3_int64)86400;

  /* Number of 100-nanosecond intervals in half of a day */
  static const sqlite3_int64 ntuPerHalfDay =
      10000000*(sqlite3_int64)43200;

  /* 2^32 - to avoid use of LL and warnings in gcc */
  static const sqlite3_int64 max32BitValue =
      (sqlite3_int64)2000000000 + (sqlite3_int64)2000000000 + (sqlite3_int64)294967296;

#if SQLITE_OS_WINCE
  SYSTEMTIME time;
  GetSystemTime(&time);
  /* if SystemTimeToFileTime() fails, it returns zero. */
  if (!SystemTimeToFileTime(&time,&ft)){
    return 1;
  }
#else
  GetSystemTimeAsFileTime( &ft );
#endif
  UNUSED_PARAMETER(pVfs);
  timeW = (((sqlite3_int64)ft.dwHighDateTime)*max32BitValue) + (sqlite3_int64)ft.dwLowDateTime;
  timeF = timeW % ntuPerDay;          /* fractional days (100-nanoseconds) */
  timeW = timeW / ntuPerDay;          /* whole days */
  timeW = timeW + 2305813;            /* add whole days (from 2305813.5) */
  timeF = timeF + ntuPerHalfDay;      /* add half a day (from 2305813.5) */
  timeW = timeW + (timeF/ntuPerDay);  /* add whole day if half day made one */
  timeF = timeF % ntuPerDay;          /* compute new fractional days */
  *prNow = (double)timeW + ((double)timeF / (double)ntuPerDay);
#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = ((double)sqlite3_current_time + (double)43200) / (double)86400 + (double)2440587;
  }
#endif
  return 0;
}

/*
** The idea is that this function works like a combination of
** GetLastError() and FormatMessage() on windows (or errno and
** strerror_r() on unix). After an error is returned by an OS
** function, SQLite calls this function with zBuf pointing to
** a buffer of nBuf bytes. The OS layer should populate the
** buffer with a nul-terminated UTF-8 encoded error message
** describing the last IO error to have occurred within the calling
** thread.
**
** If the error message is too large for the supplied buffer,
** it should be truncated. The return value of xGetLastError
** is zero if the error message fits in the buffer, or non-zero
** otherwise (if the message was truncated). If non-zero is returned,
** then it is not necessary to include the nul-terminator character
** in the output buffer.
**
** Not supplying an error message will have no adverse effect
** on SQLite. It is fine to have an implementation that never
** returns an error message:
**
**   int xGetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
**     assert(zBuf[0]=='\0');
**     return 0;
**   }
**
** However if an error message is supplied, it will be incorporated
** by sqlite into the error message available to the user using
** sqlite3_errmsg(), possibly making IO errors easier to debug.
*/
static int winGetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
  UNUSED_PARAMETER(pVfs);
  return getLastErrorMsg(nBuf, zBuf);
}

/*
** Initialize and deinitialize the operating system interface.
*/
SQLITE_API int sqlite3_os_init(void){
  static sqlite3_vfs winVfs = {
    1,                 /* iVersion */
    sizeof(winFile),   /* szOsFile */
    MAX_PATH,          /* mxPathname */
    0,                 /* pNext */
    "win32",           /* zName */
    0,                 /* pAppData */

    winOpen,           /* xOpen */
    winDelete,         /* xDelete */
    winAccess,         /* xAccess */
    winFullPathname,   /* xFullPathname */
    winDlOpen,         /* xDlOpen */
    winDlError,        /* xDlError */
    winDlSym,          /* xDlSym */
    winDlClose,        /* xDlClose */
    winRandomness,     /* xRandomness */
    winSleep,          /* xSleep */
    winCurrentTime,    /* xCurrentTime */
    winGetLastError    /* xGetLastError */
  };

  sqlite3_vfs_register(&winVfs, 1);
  return SQLITE_OK;
}
SQLITE_API int sqlite3_os_end(void){
  return SQLITE_OK;
}

#endif /* SQLITE_OS_WIN */

/************** End of os_win.c **********************************************/
/************** Begin file bitvec.c ******************************************/
/*
** 2008 February 16
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements an object that represents a fixed-length
** bitmap.  Bits are numbered starting with 1.
**
** A bitmap is used to record which pages of a database file have been
** journalled during a transaction, or which pages have the "dont-write"
** property.  Usually only a few pages are meet either condition.
** So the bitmap is usually sparse and has low cardinality.
** But sometimes (for example when during a DROP of a large table) most
** or all of the pages in a database can get journalled.  In those cases,
** the bitmap becomes dense with high cardinality.  The algorithm needs
** to handle both cases well.
**
** The size of the bitmap is fixed when the object is created.
**
** All bits are clear when the bitmap is created.  Individual bits
** may be set or cleared one at a time.
**
** Test operations are about 100 times more common that set operations.
** Clear operations are exceedingly rare.  There are usually between
** 5 and 500 set operations per Bitvec object, though the number of sets can
** sometimes grow into tens of thousands or larger.  The size of the
** Bitvec object is the number of pages in the database file at the
** start of a transaction, and is thus usually less than a few thousand,
** but can be as large as 2 billion for a really big database.
*/

/* Size of the Bitvec structure in bytes. */
#define BITVEC_SZ        (sizeof(void*)*128)  /* 512 on 32bit.  1024 on 64bit */

/* Round the union size down to the nearest pointer boundary, since that's how
** it will be aligned within the Bitvec struct. */
#define BITVEC_USIZE     (((BITVEC_SZ-(3*sizeof(u32)))/sizeof(Bitvec*))*sizeof(Bitvec*))

/* Type of the array "element" for the bitmap representation.
** Should be a power of 2, and ideally, evenly divide into BITVEC_USIZE.
** Setting this to the "natural word" size of your CPU may improve
** performance. */
#define BITVEC_TELEM     u8
/* Size, in bits, of the bitmap element. */
#define BITVEC_SZELEM    8
/* Number of elements in a bitmap array. */
#define BITVEC_NELEM     (BITVEC_USIZE/sizeof(BITVEC_TELEM))
/* Number of bits in the bitmap array. */
#define BITVEC_NBIT      (BITVEC_NELEM*BITVEC_SZELEM)

/* Number of u32 values in hash table. */
#define BITVEC_NINT      (BITVEC_USIZE/sizeof(u32))
/* Maximum number of entries in hash table before
** sub-dividing and re-hashing. */
#define BITVEC_MXHASH    (BITVEC_NINT/2)
/* Hashing function for the aHash representation.
** Empirical testing showed that the *37 multiplier
** (an arbitrary prime)in the hash function provided
** no fewer collisions than the no-op *1. */
#define BITVEC_HASH(X)   (((X)*1)%BITVEC_NINT)

#define BITVEC_NPTR      (BITVEC_USIZE/sizeof(Bitvec *))


/*
** A bitmap is an instance of the following structure.
**
** This bitmap records the existance of zero or more bits
** with values between 1 and iSize, inclusive.
**
** There are three possible representations of the bitmap.
** If iSize<=BITVEC_NBIT, then Bitvec.u.aBitmap[] is a straight
** bitmap.  The least significant bit is bit 1.
**
** If iSize>BITVEC_NBIT and iDivisor==0 then Bitvec.u.aHash[] is
** a hash table that will hold up to BITVEC_MXHASH distinct values.
**
** Otherwise, the value i is redirected into one of BITVEC_NPTR
** sub-bitmaps pointed to by Bitvec.u.apSub[].  Each subbitmap
** handles up to iDivisor separate values of i.  apSub[0] holds
** values between 1 and iDivisor.  apSub[1] holds values between
** iDivisor+1 and 2*iDivisor.  apSub[N] holds values between
** N*iDivisor+1 and (N+1)*iDivisor.  Each subbitmap is normalized
** to hold deal with values between 1 and iDivisor.
*/
struct Bitvec {
  u32 iSize;      /* Maximum bit index.  Max iSize is 4,294,967,296. */
  u32 nSet;       /* Number of bits that are set - only valid for aHash
                  ** element.  Max is BITVEC_NINT.  For BITVEC_SZ of 512,
                  ** this would be 125. */
  u32 iDivisor;   /* Number of bits handled by each apSub[] entry. */
                  /* Should >=0 for apSub element. */
                  /* Max iDivisor is max(u32) / BITVEC_NPTR + 1.  */
                  /* For a BITVEC_SZ of 512, this would be 34,359,739. */
  union {
    BITVEC_TELEM aBitmap[BITVEC_NELEM];    /* Bitmap representation */
    u32 aHash[BITVEC_NINT];      /* Hash table representation */
    Bitvec *apSub[BITVEC_NPTR];  /* Recursive representation */
  } u;
};

/*
** Create a new bitmap object able to handle bits between 0 and iSize,
** inclusive.  Return a pointer to the new object.  Return NULL if
** malloc fails.
*/
SQLITE_PRIVATE Bitvec *sqlite3BitvecCreate(u32 iSize){
  Bitvec *p;
  assert( sizeof(*p)==BITVEC_SZ );
  p = sqlite3MallocZero( sizeof(*p) );
  if( p ){
    p->iSize = iSize;
  }
  return p;
}

/*
** Check to see if the i-th bit is set.  Return true or false.
** If p is NULL (if the bitmap has not been created) or if
** i is out of range, then return false.
*/
SQLITE_PRIVATE int sqlite3BitvecTest(Bitvec *p, u32 i){
  if( p==0 ) return 0;
  if( i>p->iSize || i==0 ) return 0;
  i--;
  while( p->iDivisor ){
    u32 bin = i/p->iDivisor;
    i = i%p->iDivisor;
    p = p->u.apSub[bin];
    if (!p) {
      return 0;
    }
  }
  if( p->iSize<=BITVEC_NBIT ){
    return (p->u.aBitmap[i/BITVEC_SZELEM] & (1<<(i&(BITVEC_SZELEM-1))))!=0;
  } else{
    u32 h = BITVEC_HASH(i++);
    while( p->u.aHash[h] ){
      if( p->u.aHash[h]==i ) return 1;
      h = (h+1) % BITVEC_NINT;
    }
    return 0;
  }
}

/*
** Set the i-th bit.  Return 0 on success and an error code if
** anything goes wrong.
**
** This routine might cause sub-bitmaps to be allocated.  Failing
** to get the memory needed to hold the sub-bitmap is the only
** that can go wrong with an insert, assuming p and i are valid.
**
** The calling function must ensure that p is a valid Bitvec object
** and that the value for "i" is within range of the Bitvec object.
** Otherwise the behavior is undefined.
*/
SQLITE_PRIVATE int sqlite3BitvecSet(Bitvec *p, u32 i){
  u32 h;
  if( p==0 ) return SQLITE_OK;
  assert( i>0 );
  assert( i<=p->iSize );
  i--;
  while((p->iSize > BITVEC_NBIT) && p->iDivisor) {
    u32 bin = i/p->iDivisor;
    i = i%p->iDivisor;
    if( p->u.apSub[bin]==0 ){
      p->u.apSub[bin] = sqlite3BitvecCreate( p->iDivisor );
      if( p->u.apSub[bin]==0 ) return SQLITE_NOMEM;
    }
    p = p->u.apSub[bin];
  }
  if( p->iSize<=BITVEC_NBIT ){
    p->u.aBitmap[i/BITVEC_SZELEM] |= 1 << (i&(BITVEC_SZELEM-1));
    return SQLITE_OK;
  }
  h = BITVEC_HASH(i++);
  /* if there wasn't a hash collision, and this doesn't */
  /* completely fill the hash, then just add it without */
  /* worring about sub-dividing and re-hashing. */
  if( !p->u.aHash[h] ){
    if (p->nSet<(BITVEC_NINT-1)) {
      goto bitvec_set_end;
    } else {
      goto bitvec_set_rehash;
    }
  }
  /* there was a collision, check to see if it's already */
  /* in hash, if not, try to find a spot for it */
  do {
    if( p->u.aHash[h]==i ) return SQLITE_OK;
    h++;
    if( h>=BITVEC_NINT ) h = 0;
  } while( p->u.aHash[h] );
  /* we didn't find it in the hash.  h points to the first */
  /* available free spot. check to see if this is going to */
  /* make our hash too "full".  */
bitvec_set_rehash:
  if( p->nSet>=BITVEC_MXHASH ){
    unsigned int j;
    int rc;
    u32 *aiValues = sqlite3StackAllocRaw(0, sizeof(p->u.aHash));
    if( aiValues==0 ){
      return SQLITE_NOMEM;
    }else{
      memcpy(aiValues, p->u.aHash, sizeof(p->u.aHash));
      memset(p->u.apSub, 0, sizeof(p->u.apSub));
      p->iDivisor = (p->iSize + BITVEC_NPTR - 1)/BITVEC_NPTR;
      rc = sqlite3BitvecSet(p, i);
      for(j=0; j<BITVEC_NINT; j++){
        if( aiValues[j] ) rc |= sqlite3BitvecSet(p, aiValues[j]);
      }
      sqlite3StackFree(0, aiValues);
      return rc;
    }
  }
bitvec_set_end:
  p->nSet++;
  p->u.aHash[h] = i;
  return SQLITE_OK;
}

/*
** Clear the i-th bit.
**
** pBuf must be a pointer to at least BITVEC_SZ bytes of temporary storage
** that BitvecClear can use to rebuilt its hash table.
*/
SQLITE_PRIVATE void sqlite3BitvecClear(Bitvec *p, u32 i, void *pBuf){
  if( p==0 ) return;
  assert( i>0 );
  i--;
  while( p->iDivisor ){
    u32 bin = i/p->iDivisor;
    i = i%p->iDivisor;
    p = p->u.apSub[bin];
    if (!p) {
      return;
    }
  }
  if( p->iSize<=BITVEC_NBIT ){
    p->u.aBitmap[i/BITVEC_SZELEM] &= ~(1 << (i&(BITVEC_SZELEM-1)));
  }else{
    unsigned int j;
    u32 *aiValues = pBuf;
    memcpy(aiValues, p->u.aHash, sizeof(p->u.aHash));
    memset(p->u.aHash, 0, sizeof(p->u.aHash));
    p->nSet = 0;
    for(j=0; j<BITVEC_NINT; j++){
      if( aiValues[j] && aiValues[j]!=(i+1) ){
        u32 h = BITVEC_HASH(aiValues[j]-1);
        p->nSet++;
        while( p->u.aHash[h] ){
          h++;
          if( h>=BITVEC_NINT ) h = 0;
        }
        p->u.aHash[h] = aiValues[j];
      }
    }
  }
}

/*
** Destroy a bitmap object.  Reclaim all memory used.
*/
SQLITE_PRIVATE void sqlite3BitvecDestroy(Bitvec *p){
  if( p==0 ) return;
  if( p->iDivisor ){
    unsigned int i;
    for(i=0; i<BITVEC_NPTR; i++){
      sqlite3BitvecDestroy(p->u.apSub[i]);
    }
  }
  sqlite3_free(p);
}

/*
** Return the value of the iSize parameter specified when Bitvec *p
** was created.
*/
SQLITE_PRIVATE u32 sqlite3BitvecSize(Bitvec *p){
  return p->iSize;
}

#ifndef SQLITE_OMIT_BUILTIN_TEST
/*
** Let V[] be an array of unsigned characters sufficient to hold
** up to N bits.  Let I be an integer between 0 and N.  0<=I<N.
** Then the following macros can be used to set, clear, or test
** individual bits within V.
*/
#define SETBIT(V,I)      V[I>>3] |= (1<<(I&7))
#define CLEARBIT(V,I)    V[I>>3] &= ~(1<<(I&7))
#define TESTBIT(V,I)     (V[I>>3]&(1<<(I&7)))!=0

/*
** This routine runs an extensive test of the Bitvec code.
**
** The input is an array of integers that acts as a program
** to test the Bitvec.  The integers are opcodes followed
** by 0, 1, or 3 operands, depending on the opcode.  Another
** opcode follows immediately after the last operand.
**
** There are 6 opcodes numbered from 0 through 5.  0 is the
** "halt" opcode and causes the test to end.
**
**    0          Halt and return the number of errors
**    1 N S X    Set N bits beginning with S and incrementing by X
**    2 N S X    Clear N bits beginning with S and incrementing by X
**    3 N        Set N randomly chosen bits
**    4 N        Clear N randomly chosen bits
**    5 N S X    Set N bits from S increment X in array only, not in bitvec
**
** The opcodes 1 through 4 perform set and clear operations are performed
** on both a Bitvec object and on a linear array of bits obtained from malloc.
** Opcode 5 works on the linear array only, not on the Bitvec.
** Opcode 5 is used to deliberately induce a fault in order to
** confirm that error detection works.
**
** At the conclusion of the test the linear array is compared
** against the Bitvec object.  If there are any differences,
** an error is returned.  If they are the same, zero is returned.
**
** If a memory allocation error occurs, return -1.
*/
SQLITE_PRIVATE int sqlite3BitvecBuiltinTest(int sz, int *aOp){
  Bitvec *pBitvec = 0;
  unsigned char *pV = 0;
  int rc = -1;
  int i, nx, pc, op;
  void *pTmpSpace;

  /* Allocate the Bitvec to be tested and a linear array of
  ** bits to act as the reference */
  pBitvec = sqlite3BitvecCreate( sz );
  pV = sqlite3_malloc( (sz+7)/8 + 1 );
  pTmpSpace = sqlite3_malloc(BITVEC_SZ);
  if( pBitvec==0 || pV==0 || pTmpSpace==0  ) goto bitvec_end;
  memset(pV, 0, (sz+7)/8 + 1);

  /* NULL pBitvec tests */
  sqlite3BitvecSet(0, 1);
  sqlite3BitvecClear(0, 1, pTmpSpace);

  /* Run the program */
  pc = 0;
  while( (op = aOp[pc])!=0 ){
    switch( op ){
      case 1:
      case 2:
      case 5: {
        nx = 4;
        i = aOp[pc+2] - 1;
        aOp[pc+2] += aOp[pc+3];
        break;
      }
      case 3:
      case 4:
      default: {
        nx = 2;
        sqlite3_randomness(sizeof(i), &i);
        break;
      }
    }
    if( (--aOp[pc+1]) > 0 ) nx = 0;
    pc += nx;
    i = (i & 0x7fffffff)%sz;
    if( (op & 1)!=0 ){
      SETBIT(pV, (i+1));
      if( op!=5 ){
        if( sqlite3BitvecSet(pBitvec, i+1) ) goto bitvec_end;
      }
    }else{
      CLEARBIT(pV, (i+1));
      sqlite3BitvecClear(pBitvec, i+1, pTmpSpace);
    }
  }

  /* Test to make sure the linear array exactly matches the
  ** Bitvec object.  Start with the assumption that they do
  ** match (rc==0).  Change rc to non-zero if a discrepancy
  ** is found.
  */
  rc = sqlite3BitvecTest(0,0) + sqlite3BitvecTest(pBitvec, sz+1)
          + sqlite3BitvecTest(pBitvec, 0)
          + (sqlite3BitvecSize(pBitvec) - sz);
  for(i=1; i<=sz; i++){
    if(  (TESTBIT(pV,i))!=sqlite3BitvecTest(pBitvec,i) ){
      rc = i;
      break;
    }
  }

  /* Free allocated structure */
bitvec_end:
  sqlite3_free(pTmpSpace);
  sqlite3_free(pV);
  sqlite3BitvecDestroy(pBitvec);
  return rc;
}
#endif /* SQLITE_OMIT_BUILTIN_TEST */

/************** End of bitvec.c **********************************************/
/************** Begin file pcache.c ******************************************/
/*
** 2008 August 05
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements that page cache.
*/

/*
** A complete page cache is an instance of this structure.
*/
struct PCache {
  PgHdr *pDirty, *pDirtyTail;         /* List of dirty pages in LRU order */
  PgHdr *pSynced;                     /* Last synced page in dirty page list */
  int nRef;                           /* Number of referenced pages */
  int nMax;                           /* Configured cache size */
  int szPage;                         /* Size of every page in this cache */
  int szExtra;                        /* Size of extra space for each page */
  int bPurgeable;                     /* True if pages are on backing store */
  int (*xStress)(void*,PgHdr*);       /* Call to try make a page clean */
  void *pStress;                      /* Argument to xStress */
  sqlite3_pcache *pCache;             /* Pluggable cache module */
  PgHdr *pPage1;                      /* Reference to page 1 */
};

/*
** Some of the assert() macros in this code are too expensive to run
** even during normal debugging.  Use them only rarely on long-running
** tests.  Enable the expensive asserts using the
** -DSQLITE_ENABLE_EXPENSIVE_ASSERT=1 compile-time option.
*/
#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
# define expensive_assert(X)  assert(X)
#else
# define expensive_assert(X)
#endif

/********************************** Linked List Management ********************/

#if !defined(NDEBUG) && defined(SQLITE_ENABLE_EXPENSIVE_ASSERT)
/*
** Check that the pCache->pSynced variable is set correctly. If it
** is not, either fail an assert or return zero. Otherwise, return
** non-zero. This is only used in debugging builds, as follows:
**
**   expensive_assert( pcacheCheckSynced(pCache) );
*/
static int pcacheCheckSynced(PCache *pCache){
  PgHdr *p;
  for(p=pCache->pDirtyTail; p!=pCache->pSynced; p=p->pDirtyPrev){
    assert( p->nRef || (p->flags&PGHDR_NEED_SYNC) );
  }
  return (p==0 || p->nRef || (p->flags&PGHDR_NEED_SYNC)==0);
}
#endif /* !NDEBUG && SQLITE_ENABLE_EXPENSIVE_ASSERT */

/*
** Remove page pPage from the list of dirty pages.
*/
static void pcacheRemoveFromDirtyList(PgHdr *pPage){
  PCache *p = pPage->pCache;

  assert( pPage->pDirtyNext || pPage==p->pDirtyTail );
  assert( pPage->pDirtyPrev || pPage==p->pDirty );

  /* Update the PCache1.pSynced variable if necessary. */
  if( p->pSynced==pPage ){
    PgHdr *pSynced = pPage->pDirtyPrev;
    while( pSynced && (pSynced->flags&PGHDR_NEED_SYNC) ){
      pSynced = pSynced->pDirtyPrev;
    }
    p->pSynced = pSynced;
  }

  if( pPage->pDirtyNext ){
    pPage->pDirtyNext->pDirtyPrev = pPage->pDirtyPrev;
  }else{
    assert( pPage==p->pDirtyTail );
    p->pDirtyTail = pPage->pDirtyPrev;
  }
  if( pPage->pDirtyPrev ){
    pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext;
  }else{
    assert( pPage==p->pDirty );
    p->pDirty = pPage->pDirtyNext;
  }
  pPage->pDirtyNext = 0;
  pPage->pDirtyPrev = 0;

  expensive_assert( pcacheCheckSynced(p) );
}

/*
** Add page pPage to the head of the dirty list (PCache1.pDirty is set to
** pPage).
*/
static void pcacheAddToDirtyList(PgHdr *pPage){
  PCache *p = pPage->pCache;

  assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage );

  pPage->pDirtyNext = p->pDirty;
  if( pPage->pDirtyNext ){
    assert( pPage->pDirtyNext->pDirtyPrev==0 );
    pPage->pDirtyNext->pDirtyPrev = pPage;
  }
  p->pDirty = pPage;
  if( !p->pDirtyTail ){
    p->pDirtyTail = pPage;
  }
  if( !p->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){
    p->pSynced = pPage;
  }
  expensive_assert( pcacheCheckSynced(p) );
}

/*
** Wrapper around the pluggable caches xUnpin method. If the cache is
** being used for an in-memory database, this function is a no-op.
*/
static void pcacheUnpin(PgHdr *p){
  PCache *pCache = p->pCache;
  if( pCache->bPurgeable ){
    if( p->pgno==1 ){
      pCache->pPage1 = 0;
    }
    sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 0);
  }
}

/*************************************************** General Interfaces ******
**
** Initialize and shutdown the page cache subsystem. Neither of these
** functions are threadsafe.
*/
SQLITE_PRIVATE int sqlite3PcacheInitialize(void){
  if( sqlite3GlobalConfig.pcache.xInit==0 ){
    sqlite3PCacheSetDefault();
  }
  return sqlite3GlobalConfig.pcache.xInit(sqlite3GlobalConfig.pcache.pArg);
}
SQLITE_PRIVATE void sqlite3PcacheShutdown(void){
  if( sqlite3GlobalConfig.pcache.xShutdown ){
    sqlite3GlobalConfig.pcache.xShutdown(sqlite3GlobalConfig.pcache.pArg);
  }
}

/*
** Return the size in bytes of a PCache object.
*/
SQLITE_PRIVATE int sqlite3PcacheSize(void){ return sizeof(PCache); }

/*
** Create a new PCache object. Storage space to hold the object
** has already been allocated and is passed in as the p pointer.
** The caller discovers how much space needs to be allocated by
** calling sqlite3PcacheSize().
*/
SQLITE_PRIVATE void sqlite3PcacheOpen(
  int szPage,                  /* Size of every page */
  int szExtra,                 /* Extra space associated with each page */
  int bPurgeable,              /* True if pages are on backing store */
  int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */
  void *pStress,               /* Argument to xStress */
  PCache *p                    /* Preallocated space for the PCache */
){
  memset(p, 0, sizeof(PCache));
  p->szPage = szPage;
  p->szExtra = szExtra;
  p->bPurgeable = bPurgeable;
  p->xStress = xStress;
  p->pStress = pStress;
  p->nMax = 100;
}

/*
** Change the page size for PCache object. The caller must ensure that there
** are no outstanding page references when this function is called.
*/
SQLITE_PRIVATE void sqlite3PcacheSetPageSize(PCache *pCache, int szPage){
  assert( pCache->nRef==0 && pCache->pDirty==0 );
  if( pCache->pCache ){
    sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache);
    pCache->pCache = 0;
    pCache->pPage1 = 0;
  }
  pCache->szPage = szPage;
}

/*
** Try to obtain a page from the cache.
*/
SQLITE_PRIVATE int sqlite3PcacheFetch(
  PCache *pCache,       /* Obtain the page from this cache */
  Pgno pgno,            /* Page number to obtain */
  int createFlag,       /* If true, create page if it does not exist already */
  PgHdr **ppPage        /* Write the page here */
){
  PgHdr *pPage = 0;
  int eCreate;

  assert( pCache!=0 );
  assert( createFlag==1 || createFlag==0 );
  assert( pgno>0 );

  /* If the pluggable cache (sqlite3_pcache*) has not been allocated,
  ** allocate it now.
  */
  if( !pCache->pCache && createFlag ){
    sqlite3_pcache *p;
    int nByte;
    nByte = pCache->szPage + pCache->szExtra + sizeof(PgHdr);
    p = sqlite3GlobalConfig.pcache.xCreate(nByte, pCache->bPurgeable);
    if( !p ){
      return SQLITE_NOMEM;
    }
    sqlite3GlobalConfig.pcache.xCachesize(p, pCache->nMax);
    pCache->pCache = p;
  }

  eCreate = createFlag * (1 + (!pCache->bPurgeable || !pCache->pDirty));
  if( pCache->pCache ){
    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, eCreate);
  }

  if( !pPage && eCreate==1 ){
    PgHdr *pPg;

    /* Find a dirty page to write-out and recycle. First try to find a
    ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC
    ** cleared), but if that is not possible settle for any other
    ** unreferenced dirty page.
    */
    expensive_assert( pcacheCheckSynced(pCache) );
    for(pPg=pCache->pSynced;
        pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC));
        pPg=pPg->pDirtyPrev
    );
    pCache->pSynced = pPg;
    if( !pPg ){
      for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
    }
    if( pPg ){
      int rc;
      rc = pCache->xStress(pCache->pStress, pPg);
      if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
        return rc;
      }
    }

    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2);
  }

  if( pPage ){
    if( !pPage->pData ){
      memset(pPage, 0, sizeof(PgHdr) + pCache->szExtra);
      pPage->pExtra = (void*)&pPage[1];
      pPage->pData = (void *)&((char *)pPage)[sizeof(PgHdr) + pCache->szExtra];
      pPage->pCache = pCache;
      pPage->pgno = pgno;
    }
    assert( pPage->pCache==pCache );
    assert( pPage->pgno==pgno );
    assert( pPage->pExtra==(void *)&pPage[1] );

    if( 0==pPage->nRef ){
      pCache->nRef++;
    }
    pPage->nRef++;
    if( pgno==1 ){
      pCache->pPage1 = pPage;
    }
  }
  *ppPage = pPage;
  return (pPage==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK;
}

/*
** Decrement the reference count on a page. If the page is clean and the
** reference count drops to 0, then it is made elible for recycling.
*/
SQLITE_PRIVATE void sqlite3PcacheRelease(PgHdr *p){
  assert( p->nRef>0 );
  p->nRef--;
  if( p->nRef==0 ){
    PCache *pCache = p->pCache;
    pCache->nRef--;
    if( (p->flags&PGHDR_DIRTY)==0 ){
      pcacheUnpin(p);
    }else{
      /* Move the page to the head of the dirty list. */
      pcacheRemoveFromDirtyList(p);
      pcacheAddToDirtyList(p);
    }
  }
}

/*
** Increase the reference count of a supplied page by 1.
*/
SQLITE_PRIVATE void sqlite3PcacheRef(PgHdr *p){
  assert(p->nRef>0);
  p->nRef++;
}

/*
** Drop a page from the cache. There must be exactly one reference to the
** page. This function deletes that reference, so after it returns the
** page pointed to by p is invalid.
*/
SQLITE_PRIVATE void sqlite3PcacheDrop(PgHdr *p){
  PCache *pCache;
  assert( p->nRef==1 );
  if( p->flags&PGHDR_DIRTY ){
    pcacheRemoveFromDirtyList(p);
  }
  pCache = p->pCache;
  pCache->nRef--;
  if( p->pgno==1 ){
    pCache->pPage1 = 0;
  }
  sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 1);
}

/*
** Make sure the page is marked as dirty. If it isn't dirty already,
** make it so.
*/
SQLITE_PRIVATE void sqlite3PcacheMakeDirty(PgHdr *p){
  p->flags &= ~PGHDR_DONT_WRITE;
  assert( p->nRef>0 );
  if( 0==(p->flags & PGHDR_DIRTY) ){
    p->flags |= PGHDR_DIRTY;
    pcacheAddToDirtyList( p);
  }
}

/*
** Make sure the page is marked as clean. If it isn't clean already,
** make it so.
*/
SQLITE_PRIVATE void sqlite3PcacheMakeClean(PgHdr *p){
  if( (p->flags & PGHDR_DIRTY) ){
    pcacheRemoveFromDirtyList(p);
    p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC);
    if( p->nRef==0 ){
      pcacheUnpin(p);
    }
  }
}

/*
** Make every page in the cache clean.
*/
SQLITE_PRIVATE void sqlite3PcacheCleanAll(PCache *pCache){
  PgHdr *p;
  while( (p = pCache->pDirty)!=0 ){
    sqlite3PcacheMakeClean(p);
  }
}

/*
** Clear the PGHDR_NEED_SYNC flag from all dirty pages.
*/
SQLITE_PRIVATE void sqlite3PcacheClearSyncFlags(PCache *pCache){
  PgHdr *p;
  for(p=pCache->pDirty; p; p=p->pDirtyNext){
    p->flags &= ~PGHDR_NEED_SYNC;
  }
  pCache->pSynced = pCache->pDirtyTail;
}

/*
** Change the page number of page p to newPgno.
*/
SQLITE_PRIVATE void sqlite3PcacheMove(PgHdr *p, Pgno newPgno){
  PCache *pCache = p->pCache;
  assert( p->nRef>0 );
  assert( newPgno>0 );
  sqlite3GlobalConfig.pcache.xRekey(pCache->pCache, p, p->pgno, newPgno);
  p->pgno = newPgno;
  if( (p->flags&PGHDR_DIRTY) && (p->flags&PGHDR_NEED_SYNC) ){
    pcacheRemoveFromDirtyList(p);
    pcacheAddToDirtyList(p);
  }
}

/*
** Drop every cache entry whose page number is greater than "pgno". The
** caller must ensure that there are no outstanding references to any pages
** other than page 1 with a page number greater than pgno.
**
** If there is a reference to page 1 and the pgno parameter passed to this
** function is 0, then the data area associated with page 1 is zeroed, but
** the page object is not dropped.
*/
SQLITE_PRIVATE void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){
  if( pCache->pCache ){
    PgHdr *p;
    PgHdr *pNext;
    for(p=pCache->pDirty; p; p=pNext){
      pNext = p->pDirtyNext;
      if( p->pgno>pgno ){
        assert( p->flags&PGHDR_DIRTY );
        sqlite3PcacheMakeClean(p);
      }
    }
    if( pgno==0 && pCache->pPage1 ){
      memset(pCache->pPage1->pData, 0, pCache->szPage);
      pgno = 1;
    }
    sqlite3GlobalConfig.pcache.xTruncate(pCache->pCache, pgno+1);
  }
}

/*
** Close a cache.
*/
SQLITE_PRIVATE void sqlite3PcacheClose(PCache *pCache){
  if( pCache->pCache ){
    sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache);
  }
}

/*
** Discard the contents of the cache.
*/
SQLITE_PRIVATE void sqlite3PcacheClear(PCache *pCache){
  sqlite3PcacheTruncate(pCache, 0);
}

/*
** Merge two lists of pages connected by pDirty and in pgno order.
** Do not both fixing the pDirtyPrev pointers.
*/
static PgHdr *pcacheMergeDirtyList(PgHdr *pA, PgHdr *pB){
  PgHdr result, *pTail;
  pTail = &result;
  while( pA && pB ){
    if( pA->pgno<pB->pgno ){
      pTail->pDirty = pA;
      pTail = pA;
      pA = pA->pDirty;
    }else{
      pTail->pDirty = pB;
      pTail = pB;
      pB = pB->pDirty;
    }
  }
  if( pA ){
    pTail->pDirty = pA;
  }else if( pB ){
    pTail->pDirty = pB;
  }else{
    pTail->pDirty = 0;
  }
  return result.pDirty;
}

/*
** Sort the list of pages in accending order by pgno.  Pages are
** connected by pDirty pointers.  The pDirtyPrev pointers are
** corrupted by this sort.
**
** Since there cannot be more than 2^31 distinct pages in a database,
** there cannot be more than 31 buckets required by the merge sorter.
** One extra bucket is added to catch overflow in case something
** ever changes to make the previous sentence incorrect.
*/
#define N_SORT_BUCKET  32
static PgHdr *pcacheSortDirtyList(PgHdr *pIn){
  PgHdr *a[N_SORT_BUCKET], *p;
  int i;
  memset(a, 0, sizeof(a));
  while( pIn ){
    p = pIn;
    pIn = p->pDirty;
    p->pDirty = 0;
    for(i=0; ALWAYS(i<N_SORT_BUCKET-1); i++){
      if( a[i]==0 ){
        a[i] = p;
        break;
      }else{
        p = pcacheMergeDirtyList(a[i], p);
        a[i] = 0;
      }
    }
    if( NEVER(i==N_SORT_BUCKET-1) ){
      /* To get here, there need to be 2^(N_SORT_BUCKET) elements in
      ** the input list.  But that is impossible.
      */
      a[i] = pcacheMergeDirtyList(a[i], p);
    }
  }
  p = a[0];
  for(i=1; i<N_SORT_BUCKET; i++){
    p = pcacheMergeDirtyList(p, a[i]);
  }
  return p;
}

/*
** Return a list of all dirty pages in the cache, sorted by page number.
*/
SQLITE_PRIVATE PgHdr *sqlite3PcacheDirtyList(PCache *pCache){
  PgHdr *p;
  for(p=pCache->pDirty; p; p=p->pDirtyNext){
    p->pDirty = p->pDirtyNext;
  }
  return pcacheSortDirtyList(pCache->pDirty);
}

/*
** Return the total number of referenced pages held by the cache.
*/
SQLITE_PRIVATE int sqlite3PcacheRefCount(PCache *pCache){
  return pCache->nRef;
}

/*
** Return the number of references to the page supplied as an argument.
*/
SQLITE_PRIVATE int sqlite3PcachePageRefcount(PgHdr *p){
  return p->nRef;
}

/*
** Return the total number of pages in the cache.
*/
SQLITE_PRIVATE int sqlite3PcachePagecount(PCache *pCache){
  int nPage = 0;
  if( pCache->pCache ){
    nPage = sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache);
  }
  return nPage;
}

#ifdef SQLITE_TEST
/*
** Get the suggested cache-size value.
*/
SQLITE_PRIVATE int sqlite3PcacheGetCachesize(PCache *pCache){
  return pCache->nMax;
}
#endif

/*
** Set the suggested cache-size value.
*/
SQLITE_PRIVATE void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){
  pCache->nMax = mxPage;
  if( pCache->pCache ){
    sqlite3GlobalConfig.pcache.xCachesize(pCache->pCache, mxPage);
  }
}

#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
/*
** For all dirty pages currently in the cache, invoke the specified
** callback. This is only used if the SQLITE_CHECK_PAGES macro is
** defined.
*/
SQLITE_PRIVATE void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)){
  PgHdr *pDirty;
  for(pDirty=pCache->pDirty; pDirty; pDirty=pDirty->pDirtyNext){
    xIter(pDirty);
  }
}
#endif

/************** End of pcache.c **********************************************/
/************** Begin file pcache1.c *****************************************/
/*
** 2008 November 05
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file implements the default page cache implementation (the
** sqlite3_pcache interface). It also contains part of the implementation
** of the SQLITE_CONFIG_PAGECACHE and sqlite3_release_memory() features.
** If the default page cache implementation is overriden, then neither of
** these two features are available.
*/


typedef struct PCache1 PCache1;
typedef struct PgHdr1 PgHdr1;
typedef struct PgFreeslot PgFreeslot;

/* Pointers to structures of this type are cast and returned as
** opaque sqlite3_pcache* handles
*/
struct PCache1 {
  /* Cache configuration parameters. Page size (szPage) and the purgeable
  ** flag (bPurgeable) are set when the cache is created. nMax may be
  ** modified at any time by a call to the pcache1CacheSize() method.
  ** The global mutex must be held when accessing nMax.
  */
  int szPage;                         /* Size of allocated pages in bytes */
  int bPurgeable;                     /* True if cache is purgeable */
  unsigned int nMin;                  /* Minimum number of pages reserved */
  unsigned int nMax;                  /* Configured "cache_size" value */

  /* Hash table of all pages. The following variables may only be accessed
  ** when the accessor is holding the global mutex (see pcache1EnterMutex()
  ** and pcache1LeaveMutex()).
  */
  unsigned int nRecyclable;           /* Number of pages in the LRU list */
  unsigned int nPage;                 /* Total number of pages in apHash */
  unsigned int nHash;                 /* Number of slots in apHash[] */
  PgHdr1 **apHash;                    /* Hash table for fast lookup by key */

  unsigned int iMaxKey;               /* Largest key seen since xTruncate() */
};

/*
** Each cache entry is represented by an instance of the following
** structure. A buffer of PgHdr1.pCache->szPage bytes is allocated
** directly before this structure in memory (see the PGHDR1_TO_PAGE()
** macro below).
*/
struct PgHdr1 {
  unsigned int iKey;             /* Key value (page number) */
  PgHdr1 *pNext;                 /* Next in hash table chain */
  PCache1 *pCache;               /* Cache that currently owns this page */
  PgHdr1 *pLruNext;              /* Next in LRU list of unpinned pages */
  PgHdr1 *pLruPrev;              /* Previous in LRU list of unpinned pages */
};

/*
** Free slots in the allocator used to divide up the buffer provided using
** the SQLITE_CONFIG_PAGECACHE mechanism.
*/
struct PgFreeslot {
  PgFreeslot *pNext;  /* Next free slot */
};

/*
** Global data used by this cache.
*/
static SQLITE_WSD struct PCacheGlobal {
  sqlite3_mutex *mutex;               /* static mutex MUTEX_STATIC_LRU */

  int nMaxPage;                       /* Sum of nMaxPage for purgeable caches */
  int nMinPage;                       /* Sum of nMinPage for purgeable caches */
  int nCurrentPage;                   /* Number of purgeable pages allocated */
  PgHdr1 *pLruHead, *pLruTail;        /* LRU list of unpinned pages */

  /* Variables related to SQLITE_CONFIG_PAGECACHE settings. */
  int szSlot;                         /* Size of each free slot */
  void *pStart, *pEnd;                /* Bounds of pagecache malloc range */
  PgFreeslot *pFree;                  /* Free page blocks */
  int isInit;                         /* True if initialized */
} pcache1_g;

/*
** All code in this file should access the global structure above via the
** alias "pcache1". This ensures that the WSD emulation is used when
** compiling for systems that do not support real WSD.
*/
#define pcache1 (GLOBAL(struct PCacheGlobal, pcache1_g))

/*
** When a PgHdr1 structure is allocated, the associated PCache1.szPage
** bytes of data are located directly before it in memory (i.e. the total
** size of the allocation is sizeof(PgHdr1)+PCache1.szPage byte). The
** PGHDR1_TO_PAGE() macro takes a pointer to a PgHdr1 structure as
** an argument and returns a pointer to the associated block of szPage
** bytes. The PAGE_TO_PGHDR1() macro does the opposite: its argument is
** a pointer to a block of szPage bytes of data and the return value is
** a pointer to the associated PgHdr1 structure.
**
**   assert( PGHDR1_TO_PAGE(PAGE_TO_PGHDR1(pCache, X))==X );
*/
#define PGHDR1_TO_PAGE(p)    (void*)(((char*)p) - p->pCache->szPage)
#define PAGE_TO_PGHDR1(c, p) (PgHdr1*)(((char*)p) + c->szPage)

/*
** Macros to enter and leave the global LRU mutex.
*/
#define pcache1EnterMutex() sqlite3_mutex_enter(pcache1.mutex)
#define pcache1LeaveMutex() sqlite3_mutex_leave(pcache1.mutex)

/******************************************************************************/
/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/

/*
** This function is called during initialization if a static buffer is
** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE
** verb to sqlite3_config(). Parameter pBuf points to an allocation large
** enough to contain 'n' buffers of 'sz' bytes each.
*/
SQLITE_PRIVATE void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
  if( pcache1.isInit ){
    PgFreeslot *p;
    sz = ROUNDDOWN8(sz);
    pcache1.szSlot = sz;
    pcache1.pStart = pBuf;
    pcache1.pFree = 0;
    while( n-- ){
      p = (PgFreeslot*)pBuf;
      p->pNext = pcache1.pFree;
      pcache1.pFree = p;
      pBuf = (void*)&((char*)pBuf)[sz];
    }
    pcache1.pEnd = pBuf;
  }
}

/*
** Malloc function used within this file to allocate space from the buffer
** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no
** such buffer exists or there is no space left in it, this function falls
** back to sqlite3Malloc().
*/
static void *pcache1Alloc(int nByte){
  void *p;
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( nByte<=pcache1.szSlot && pcache1.pFree ){
    assert( pcache1.isInit );
    p = (PgHdr1 *)pcache1.pFree;
    pcache1.pFree = pcache1.pFree->pNext;
    sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1);
  }else{

    /* Allocate a new buffer using sqlite3Malloc. Before doing so, exit the
    ** global pcache mutex and unlock the pager-cache object pCache. This is
    ** so that if the attempt to allocate a new buffer causes the the
    ** configured soft-heap-limit to be breached, it will be possible to
    ** reclaim memory from this pager-cache.
    */
    pcache1LeaveMutex();
    p = sqlite3Malloc(nByte);
    pcache1EnterMutex();
    if( p ){
      int sz = sqlite3MallocSize(p);
      sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
    }
  }
  return p;
}

/*
** Free an allocated buffer obtained from pcache1Alloc().
*/
static void pcache1Free(void *p){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( p==0 ) return;
  if( p>=pcache1.pStart && p<pcache1.pEnd ){
    PgFreeslot *pSlot;
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, -1);
    pSlot = (PgFreeslot*)p;
    pSlot->pNext = pcache1.pFree;
    pcache1.pFree = pSlot;
  }else{
    int iSize = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize);
    sqlite3_free(p);
  }
}

/*
** Allocate a new page object initially associated with cache pCache.
*/
static PgHdr1 *pcache1AllocPage(PCache1 *pCache){
  int nByte = sizeof(PgHdr1) + pCache->szPage;
  void *pPg = pcache1Alloc(nByte);
  PgHdr1 *p;
  if( pPg ){
    p = PAGE_TO_PGHDR1(pCache, pPg);
    if( pCache->bPurgeable ){
      pcache1.nCurrentPage++;
    }
  }else{
    p = 0;
  }
  return p;
}

/*
** Free a page object allocated by pcache1AllocPage().
**
** The pointer is allowed to be NULL, which is prudent.  But it turns out
** that the current implementation happens to never call this routine
** with a NULL pointer, so we mark the NULL test with ALWAYS().
*/
static void pcache1FreePage(PgHdr1 *p){
  if( ALWAYS(p) ){
    if( p->pCache->bPurgeable ){
      pcache1.nCurrentPage--;
    }
    pcache1Free(PGHDR1_TO_PAGE(p));
  }
}

/*
** Malloc function used by SQLite to obtain space from the buffer configured
** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer
** exists, this function falls back to sqlite3Malloc().
*/
SQLITE_PRIVATE void *sqlite3PageMalloc(int sz){
  void *p;
  pcache1EnterMutex();
  p = pcache1Alloc(sz);
  pcache1LeaveMutex();
  return p;
}

/*
** Free an allocated buffer obtained from sqlite3PageMalloc().
*/
SQLITE_PRIVATE void sqlite3PageFree(void *p){
  pcache1EnterMutex();
  pcache1Free(p);
  pcache1LeaveMutex();
}

/******************************************************************************/
/******** General Implementation Functions ************************************/

/*
** This function is used to resize the hash table used by the cache passed
** as the first argument.
**
** The global mutex must be held when this function is called.
*/
static int pcache1ResizeHash(PCache1 *p){
  PgHdr1 **apNew;
  unsigned int nNew;
  unsigned int i;

  assert( sqlite3_mutex_held(pcache1.mutex) );

  nNew = p->nHash*2;
  if( nNew<256 ){
    nNew = 256;
  }

  pcache1LeaveMutex();
  if( p->nHash ){ sqlite3BeginBenignMalloc(); }
  apNew = (PgHdr1 **)sqlite3_malloc(sizeof(PgHdr1 *)*nNew);
  if( p->nHash ){ sqlite3EndBenignMalloc(); }
  pcache1EnterMutex();
  if( apNew ){
    memset(apNew, 0, sizeof(PgHdr1 *)*nNew);
    for(i=0; i<p->nHash; i++){
      PgHdr1 *pPage;
      PgHdr1 *pNext = p->apHash[i];
      while( (pPage = pNext)!=0 ){
        unsigned int h = pPage->iKey % nNew;
        pNext = pPage->pNext;
        pPage->pNext = apNew[h];
        apNew[h] = pPage;
      }
    }
    sqlite3_free(p->apHash);
    p->apHash = apNew;
    p->nHash = nNew;
  }

  return (p->apHash ? SQLITE_OK : SQLITE_NOMEM);
}

/*
** This function is used internally to remove the page pPage from the
** global LRU list, if is part of it. If pPage is not part of the global
** LRU list, then this function is a no-op.
**
** The global mutex must be held when this function is called.
*/
static void pcache1PinPage(PgHdr1 *pPage){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( pPage && (pPage->pLruNext || pPage==pcache1.pLruTail) ){
    if( pPage->pLruPrev ){
      pPage->pLruPrev->pLruNext = pPage->pLruNext;
    }
    if( pPage->pLruNext ){
      pPage->pLruNext->pLruPrev = pPage->pLruPrev;
    }
    if( pcache1.pLruHead==pPage ){
      pcache1.pLruHead = pPage->pLruNext;
    }
    if( pcache1.pLruTail==pPage ){
      pcache1.pLruTail = pPage->pLruPrev;
    }
    pPage->pLruNext = 0;
    pPage->pLruPrev = 0;
    pPage->pCache->nRecyclable--;
  }
}


/*
** Remove the page supplied as an argument from the hash table
** (PCache1.apHash structure) that it is currently stored in.
**
** The global mutex must be held when this function is called.
*/
static void pcache1RemoveFromHash(PgHdr1 *pPage){
  unsigned int h;
  PCache1 *pCache = pPage->pCache;
  PgHdr1 **pp;

  h = pPage->iKey % pCache->nHash;
  for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext);
  *pp = (*pp)->pNext;

  pCache->nPage--;
}

/*
** If there are currently more than pcache.nMaxPage pages allocated, try
** to recycle pages to reduce the number allocated to pcache.nMaxPage.
*/
static void pcache1EnforceMaxPage(void){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  while( pcache1.nCurrentPage>pcache1.nMaxPage && pcache1.pLruTail ){
    PgHdr1 *p = pcache1.pLruTail;
    pcache1PinPage(p);
    pcache1RemoveFromHash(p);
    pcache1FreePage(p);
  }
}

/*
** Discard all pages from cache pCache with a page number (key value)
** greater than or equal to iLimit. Any pinned pages that meet this
** criteria are unpinned before they are discarded.
**
** The global mutex must be held when this function is called.
*/
static void pcache1TruncateUnsafe(
  PCache1 *pCache,
  unsigned int iLimit
){
  TESTONLY( unsigned int nPage = 0; )      /* Used to assert pCache->nPage is correct */
  unsigned int h;
  assert( sqlite3_mutex_held(pcache1.mutex) );
  for(h=0; h<pCache->nHash; h++){
    PgHdr1 **pp = &pCache->apHash[h];
    PgHdr1 *pPage;
    while( (pPage = *pp)!=0 ){
      if( pPage->iKey>=iLimit ){
        pCache->nPage--;
        *pp = pPage->pNext;
        pcache1PinPage(pPage);
        pcache1FreePage(pPage);
      }else{
        pp = &pPage->pNext;
        TESTONLY( nPage++; )
      }
    }
  }
  assert( pCache->nPage==nPage );
}

/******************************************************************************/
/******** sqlite3_pcache Methods **********************************************/

/*
** Implementation of the sqlite3_pcache.xInit method.
*/
static int pcache1Init(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  assert( pcache1.isInit==0 );
  memset(&pcache1, 0, sizeof(pcache1));
  if( sqlite3GlobalConfig.bCoreMutex ){
    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
  }
  pcache1.isInit = 1;
  return SQLITE_OK;
}

/*
** Implementation of the sqlite3_pcache.xShutdown method.
** Note that the static mutex allocated in xInit does
** not need to be freed.
*/
static void pcache1Shutdown(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  assert( pcache1.isInit!=0 );
  memset(&pcache1, 0, sizeof(pcache1));
}

/*
** Implementation of the sqlite3_pcache.xCreate method.
**
** Allocate a new cache.
*/
static sqlite3_pcache *pcache1Create(int szPage, int bPurgeable){
  PCache1 *pCache;

  pCache = (PCache1 *)sqlite3_malloc(sizeof(PCache1));
  if( pCache ){
    memset(pCache, 0, sizeof(PCache1));
    pCache->szPage = szPage;
    pCache->bPurgeable = (bPurgeable ? 1 : 0);
    if( bPurgeable ){
      pCache->nMin = 10;
      pcache1EnterMutex();
      pcache1.nMinPage += pCache->nMin;
      pcache1LeaveMutex();
    }
  }
  return (sqlite3_pcache *)pCache;
}

/*
** Implementation of the sqlite3_pcache.xCachesize method.
**
** Configure the cache_size limit for a cache.
*/
static void pcache1Cachesize(sqlite3_pcache *p, int nMax){
  PCache1 *pCache = (PCache1 *)p;
  if( pCache->bPurgeable ){
    pcache1EnterMutex();
    pcache1.nMaxPage += (nMax - pCache->nMax);
    pCache->nMax = nMax;
    pcache1EnforceMaxPage();
    pcache1LeaveMutex();
  }
}

/*
** Implementation of the sqlite3_pcache.xPagecount method.
*/
static int pcache1Pagecount(sqlite3_pcache *p){
  int n;
  pcache1EnterMutex();
  n = ((PCache1 *)p)->nPage;
  pcache1LeaveMutex();
  return n;
}

/*
** Implementation of the sqlite3_pcache.xFetch method.
**
** Fetch a page by key value.
**
** Whether or not a new page may be allocated by this function depends on
** the value of the createFlag argument.  0 means do not allocate a new
** page.  1 means allocate a new page if space is easily available.  2
** means to try really hard to allocate a new page.
**
** For a non-purgeable cache (a cache used as the storage for an in-memory
** database) there is really no difference between createFlag 1 and 2.  So
** the calling function (pcache.c) will never have a createFlag of 1 on
** a non-purgable cache.
**
** There are three different approaches to obtaining space for a page,
** depending on the value of parameter createFlag (which may be 0, 1 or 2).
**
**   1. Regardless of the value of createFlag, the cache is searched for a
**      copy of the requested page. If one is found, it is returned.
**
**   2. If createFlag==0 and the page is not already in the cache, NULL is
**      returned.
**
**   3. If createFlag is 1, and the page is not already in the cache,
**      and if either of the following are true, return NULL:
**
**       (a) the number of pages pinned by the cache is greater than
**           PCache1.nMax, or
**       (b) the number of pages pinned by the cache is greater than
**           the sum of nMax for all purgeable caches, less the sum of
**           nMin for all other purgeable caches.
**
**   4. If none of the first three conditions apply and the cache is marked
**      as purgeable, and if one of the following is true:
**
**       (a) The number of pages allocated for the cache is already
**           PCache1.nMax, or
**
**       (b) The number of pages allocated for all purgeable caches is
**           already equal to or greater than the sum of nMax for all
**           purgeable caches,
**
**      then attempt to recycle a page from the LRU list. If it is the right
**      size, return the recycled buffer. Otherwise, free the buffer and
**      proceed to step 5.
**
**   5. Otherwise, allocate and return a new page buffer.
*/
static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
  unsigned int nPinned;
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = 0;

  assert( pCache->bPurgeable || createFlag!=1 );
  pcache1EnterMutex();
  if( createFlag==1 ) sqlite3BeginBenignMalloc();

  /* Search the hash table for an existing entry. */
  if( pCache->nHash>0 ){
    unsigned int h = iKey % pCache->nHash;
    for(pPage=pCache->apHash[h]; pPage&&pPage->iKey!=iKey; pPage=pPage->pNext);
  }

  if( pPage || createFlag==0 ){
    pcache1PinPage(pPage);
    goto fetch_out;
  }

  /* Step 3 of header comment. */
  nPinned = pCache->nPage - pCache->nRecyclable;
  if( createFlag==1 && (
        nPinned>=(pcache1.nMaxPage+pCache->nMin-pcache1.nMinPage)
     || nPinned>=(pCache->nMax * 9 / 10)
  )){
    goto fetch_out;
  }

  if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){
    goto fetch_out;
  }

  /* Step 4. Try to recycle a page buffer if appropriate. */
  if( pCache->bPurgeable && pcache1.pLruTail && (
     (pCache->nPage+1>=pCache->nMax) || pcache1.nCurrentPage>=pcache1.nMaxPage
  )){
    pPage = pcache1.pLruTail;
    pcache1RemoveFromHash(pPage);
    pcache1PinPage(pPage);
    if( pPage->pCache->szPage!=pCache->szPage ){
      pcache1FreePage(pPage);
      pPage = 0;
    }else{
      pcache1.nCurrentPage -= (pPage->pCache->bPurgeable - pCache->bPurgeable);
    }
  }

  /* Step 5. If a usable page buffer has still not been found,
  ** attempt to allocate a new one.
  */
  if( !pPage ){
    pPage = pcache1AllocPage(pCache);
  }

  if( pPage ){
    unsigned int h = iKey % pCache->nHash;
    pCache->nPage++;
    pPage->iKey = iKey;
    pPage->pNext = pCache->apHash[h];
    pPage->pCache = pCache;
    pPage->pLruPrev = 0;
    pPage->pLruNext = 0;
    *(void **)(PGHDR1_TO_PAGE(pPage)) = 0;
    pCache->apHash[h] = pPage;
  }

fetch_out:
  if( pPage && iKey>pCache->iMaxKey ){
    pCache->iMaxKey = iKey;
  }
  if( createFlag==1 ) sqlite3EndBenignMalloc();
  pcache1LeaveMutex();
  return (pPage ? PGHDR1_TO_PAGE(pPage) : 0);
}


/*
** Implementation of the sqlite3_pcache.xUnpin method.
**
** Mark a page as unpinned (eligible for asynchronous recycling).
*/
static void pcache1Unpin(sqlite3_pcache *p, void *pPg, int reuseUnlikely){
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg);

  assert( pPage->pCache==pCache );
  pcache1EnterMutex();

  /* It is an error to call this function if the page is already
  ** part of the global LRU list.
  */
  assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );
  assert( pcache1.pLruHead!=pPage && pcache1.pLruTail!=pPage );

  if( reuseUnlikely || pcache1.nCurrentPage>pcache1.nMaxPage ){
    pcache1RemoveFromHash(pPage);
    pcache1FreePage(pPage);
  }else{
    /* Add the page to the global LRU list. Normally, the page is added to
    ** the head of the list (last page to be recycled). However, if the
    ** reuseUnlikely flag passed to this function is true, the page is added
    ** to the tail of the list (first page to be recycled).
    */
    if( pcache1.pLruHead ){
      pcache1.pLruHead->pLruPrev = pPage;
      pPage->pLruNext = pcache1.pLruHead;
      pcache1.pLruHead = pPage;
    }else{
      pcache1.pLruTail = pPage;
      pcache1.pLruHead = pPage;
    }
    pCache->nRecyclable++;
  }

  pcache1LeaveMutex();
}

/*
** Implementation of the sqlite3_pcache.xRekey method.
*/
static void pcache1Rekey(
  sqlite3_pcache *p,
  void *pPg,
  unsigned int iOld,
  unsigned int iNew
){
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg);
  PgHdr1 **pp;
  unsigned int h;
  assert( pPage->iKey==iOld );
  assert( pPage->pCache==pCache );

  pcache1EnterMutex();

  h = iOld%pCache->nHash;
  pp = &pCache->apHash[h];
  while( (*pp)!=pPage ){
    pp = &(*pp)->pNext;
  }
  *pp = pPage->pNext;

  h = iNew%pCache->nHash;
  pPage->iKey = iNew;
  pPage->pNext = pCache->apHash[h];
  pCache->apHash[h] = pPage;
  if( iNew>pCache->iMaxKey ){
    pCache->iMaxKey = iNew;
  }

  pcache1LeaveMutex();
}

/*
** Implementation of the sqlite3_pcache.xTruncate method.
**
** Discard all unpinned pages in the cache with a page number equal to
** or greater than parameter iLimit. Any pinned pages with a page number
** equal to or greater than iLimit are implicitly unpinned.
*/
static void pcache1Truncate(sqlite3_pcache *p, unsigned int iLimit){
  PCache1 *pCache = (PCache1 *)p;
  pcache1EnterMutex();
  if( iLimit<=pCache->iMaxKey ){
    pcache1TruncateUnsafe(pCache, iLimit);
    pCache->iMaxKey = iLimit-1;
  }
  pcache1LeaveMutex();
}

/*
** Implementation of the sqlite3_pcache.xDestroy method.
**
** Destroy a cache allocated using pcache1Create().
*/
static void pcache1Destroy(sqlite3_pcache *p){
  PCache1 *pCache = (PCache1 *)p;
  pcache1EnterMutex();
  pcache1TruncateUnsafe(pCache, 0);
  pcache1.nMaxPage -= pCache->nMax;
  pcache1.nMinPage -= pCache->nMin;
  pcache1EnforceMaxPage();
  pcache1LeaveMutex();
  sqlite3_free(pCache->apHash);
  sqlite3_free(pCache);
}

/*
** This function is called during initialization (sqlite3_initialize()) to
** install the default pluggable cache module, assuming the user has not
** already provided an alternative.
*/
SQLITE_PRIVATE void sqlite3PCacheSetDefault(void){
  static sqlite3_pcache_methods defaultMethods = {
    0,                       /* pArg */
    pcache1Init,             /* xInit */
    pcache1Shutdown,         /* xShutdown */
    pcache1Create,           /* xCreate */
    pcache1Cachesize,        /* xCachesize */
    pcache1Pagecount,        /* xPagecount */
    pcache1Fetch,            /* xFetch */
    pcache1Unpin,            /* xUnpin */
    pcache1Rekey,            /* xRekey */
    pcache1Truncate,         /* xTruncate */
    pcache1Destroy           /* xDestroy */
  };
  sqlite3_config(SQLITE_CONFIG_PCACHE, &defaultMethods);
}

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
/*
** This function is called to free superfluous dynamically allocated memory
** held by the pager system. Memory in use by any SQLite pager allocated
** by the current thread may be sqlite3_free()ed.
**
** nReq is the number of bytes of memory required. Once this much has
** been released, the function returns. The return value is the total number
** of bytes of memory released.
*/
SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int nReq){
  int nFree = 0;
  if( pcache1.pStart==0 ){
    PgHdr1 *p;
    pcache1EnterMutex();
    while( (nReq<0 || nFree<nReq) && (p=pcache1.pLruTail) ){
      nFree += sqlite3MallocSize(PGHDR1_TO_PAGE(p));
      pcache1PinPage(p);
      pcache1RemoveFromHash(p);
      pcache1FreePage(p);
    }
    pcache1LeaveMutex();
  }
  return nFree;
}
#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */

#ifdef SQLITE_TEST
/*
** This function is used by test procedures to inspect the internal state
** of the global cache.
*/
SQLITE_PRIVATE void sqlite3PcacheStats(
  int *pnCurrent,      /* OUT: Total number of pages cached */
  int *pnMax,          /* OUT: Global maximum cache size */
  int *pnMin,          /* OUT: Sum of PCache1.nMin for purgeable caches */
  int *pnRecyclable    /* OUT: Total number of pages available for recycling */
){
  PgHdr1 *p;
  int nRecyclable = 0;
  for(p=pcache1.pLruHead; p; p=p->pLruNext){
    nRecyclable++;
  }
  *pnCurrent = pcache1.nCurrentPage;
  *pnMax = pcache1.nMaxPage;
  *pnMin = pcache1.nMinPage;
  *pnRecyclable = nRecyclable;
}
#endif

/************** End of pcache1.c *********************************************/
/************** Begin file rowset.c ******************************************/
/*
** 2008 December 3
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This module implements an object we call a "RowSet".
**
** The RowSet object is a collection of rowids.  Rowids
** are inserted into the RowSet in an arbitrary order.  Inserts
** can be intermixed with tests to see if a given rowid has been
** previously inserted into the RowSet.
**
** After all inserts are finished, it is possible to extract the
** elements of the RowSet in sorted order.  Once this extraction
** process has started, no new elements may be inserted.
**
** Hence, the primitive operations for a RowSet are:
**
**    CREATE
**    INSERT
**    TEST
**    SMALLEST
**    DESTROY
**
** The CREATE and DESTROY primitives are the constructor and destructor,
** obviously.  The INSERT primitive adds a new element to the RowSet.
** TEST checks to see if an element is already in the RowSet.  SMALLEST
** extracts the least value from the RowSet.
**
** The INSERT primitive might allocate additional memory.  Memory is
** allocated in chunks so most INSERTs do no allocation.  There is an
** upper bound on the size of allocated memory.  No memory is freed
** until DESTROY.
**
** The TEST primitive includes a "batch" number.  The TEST primitive
** will only see elements that were inserted before the last change
** in the batch number.  In other words, if an INSERT occurs between
** two TESTs where the TESTs have the same batch nubmer, then the
** value added by the INSERT will not be visible to the second TEST.
** The initial batch number is zero, so if the very first TEST contains
** a non-zero batch number, it will see all prior INSERTs.
**
** No INSERTs may occurs after a SMALLEST.  An assertion will fail if
** that is attempted.
**
** The cost of an INSERT is roughly constant.  (Sometime new memory
** has to be allocated on an INSERT.)  The cost of a TEST with a new
** batch number is O(NlogN) where N is the number of elements in the RowSet.
** The cost of a TEST using the same batch number is O(logN).  The cost
** of the first SMALLEST is O(NlogN).  Second and subsequent SMALLEST
** primitives are constant time.  The cost of DESTROY is O(N).
**
** There is an added cost of O(N) when switching between TEST and
** SMALLEST primitives.
*/


/*
** Target size for allocation chunks.
*/
#define ROWSET_ALLOCATION_SIZE 1024

/*
** The number of rowset entries per allocation chunk.
*/
#define ROWSET_ENTRY_PER_CHUNK  \
                       ((ROWSET_ALLOCATION_SIZE-8)/sizeof(struct RowSetEntry))

/*
** Each entry in a RowSet is an instance of the following object.
*/
struct RowSetEntry {
  i64 v;                        /* ROWID value for this entry */
  struct RowSetEntry *pRight;   /* Right subtree (larger entries) or list */
  struct RowSetEntry *pLeft;    /* Left subtree (smaller entries) */
};

/*
** RowSetEntry objects are allocated in large chunks (instances of the
** following structure) to reduce memory allocation overhead.  The
** chunks are kept on a linked list so that they can be deallocated
** when the RowSet is destroyed.
*/
struct RowSetChunk {
  struct RowSetChunk *pNextChunk;        /* Next chunk on list of them all */
  struct RowSetEntry aEntry[ROWSET_ENTRY_PER_CHUNK]; /* Allocated entries */
};

/*
** A RowSet in an instance of the following structure.
**
** A typedef of this structure if found in sqliteInt.h.
*/
struct RowSet {
  struct RowSetChunk *pChunk;    /* List of all chunk allocations */
  sqlite3 *db;                   /* The database connection */
  struct RowSetEntry *pEntry;    /* List of entries using pRight */
  struct RowSetEntry *pLast;     /* Last entry on the pEntry list */
  struct RowSetEntry *pFresh;    /* Source of new entry objects */
  struct RowSetEntry *pTree;     /* Binary tree of entries */
  u16 nFresh;                    /* Number of objects on pFresh */
  u8 isSorted;                   /* True if pEntry is sorted */
  u8 iBatch;                     /* Current insert batch */
};

/*
** Turn bulk memory into a RowSet object.  N bytes of memory
** are available at pSpace.  The db pointer is used as a memory context
** for any subsequent allocations that need to occur.
** Return a pointer to the new RowSet object.
**
** It must be the case that N is sufficient to make a Rowset.  If not
** an assertion fault occurs.
**
** If N is larger than the minimum, use the surplus as an initial
** allocation of entries available to be filled.
*/
SQLITE_PRIVATE RowSet *sqlite3RowSetInit(sqlite3 *db, void *pSpace, unsigned int N){
  RowSet *p;
  assert( N >= ROUND8(sizeof(*p)) );
  p = pSpace;
  p->pChunk = 0;
  p->db = db;
  p->pEntry = 0;
  p->pLast = 0;
  p->pTree = 0;
  p->pFresh = (struct RowSetEntry*)(ROUND8(sizeof(*p)) + (char*)p);
  p->nFresh = (u16)((N - ROUND8(sizeof(*p)))/sizeof(struct RowSetEntry));
  p->isSorted = 1;
  p->iBatch = 0;
  return p;
}

/*
** Deallocate all chunks from a RowSet.  This frees all memory that
** the RowSet has allocated over its lifetime.  This routine is
** the destructor for the RowSet.
*/
SQLITE_PRIVATE void sqlite3RowSetClear(RowSet *p){
  struct RowSetChunk *pChunk, *pNextChunk;
  for(pChunk=p->pChunk; pChunk; pChunk = pNextChunk){
    pNextChunk = pChunk->pNextChunk;
    sqlite3DbFree(p->db, pChunk);
  }
  p->pChunk = 0;
  p->nFresh = 0;
  p->pEntry = 0;
  p->pLast = 0;
  p->pTree = 0;
  p->isSorted = 1;
}

/*
** Insert a new value into a RowSet.
**
** The mallocFailed flag of the database connection is set if a
** memory allocation fails.
*/
SQLITE_PRIVATE void sqlite3RowSetInsert(RowSet *p, i64 rowid){
  struct RowSetEntry *pEntry;  /* The new entry */
  struct RowSetEntry *pLast;   /* The last prior entry */
  assert( p!=0 );
  if( p->nFresh==0 ){
    struct RowSetChunk *pNew;
    pNew = sqlite3DbMallocRaw(p->db, sizeof(*pNew));
    if( pNew==0 ){
      return;
    }
    pNew->pNextChunk = p->pChunk;
    p->pChunk = pNew;
    p->pFresh = pNew->aEntry;
    p->nFresh = ROWSET_ENTRY_PER_CHUNK;
  }
  pEntry = p->pFresh++;
  p->nFresh--;
  pEntry->v = rowid;
  pEntry->pRight = 0;
  pLast = p->pLast;
  if( pLast ){
    if( p->isSorted && rowid<=pLast->v ){
      p->isSorted = 0;
    }
    pLast->pRight = pEntry;
  }else{
    assert( p->pEntry==0 ); /* Fires if INSERT after SMALLEST */
    p->pEntry = pEntry;
  }
  p->pLast = pEntry;
}

/*
** Merge two lists of RowSetEntry objects.  Remove duplicates.
**
** The input lists are connected via pRight pointers and are
** assumed to each already be in sorted order.
*/
static struct RowSetEntry *rowSetMerge(
  struct RowSetEntry *pA,    /* First sorted list to be merged */
  struct RowSetEntry *pB     /* Second sorted list to be merged */
){
  struct RowSetEntry head;
  struct RowSetEntry *pTail;

  pTail = &head;
  while( pA && pB ){
    assert( pA->pRight==0 || pA->v<=pA->pRight->v );
    assert( pB->pRight==0 || pB->v<=pB->pRight->v );
    if( pA->v<pB->v ){
      pTail->pRight = pA;
      pA = pA->pRight;
      pTail = pTail->pRight;
    }else if( pB->v<pA->v ){
      pTail->pRight = pB;
      pB = pB->pRight;
      pTail = pTail->pRight;
    }else{
      pA = pA->pRight;
    }
  }
  if( pA ){
    assert( pA->pRight==0 || pA->v<=pA->pRight->v );
    pTail->pRight = pA;
  }else{
    assert( pB==0 || pB->pRight==0 || pB->v<=pB->pRight->v );
    pTail->pRight = pB;
  }
  return head.pRight;
}

/*
** Sort all elements on the pEntry list of the RowSet into ascending order.
*/
static void rowSetSort(RowSet *p){
  unsigned int i;
  struct RowSetEntry *pEntry;
  struct RowSetEntry *aBucket[40];

  assert( p->isSorted==0 );
  memset(aBucket, 0, sizeof(aBucket));
  while( p->pEntry ){
    pEntry = p->pEntry;
    p->pEntry = pEntry->pRight;
    pEntry->pRight = 0;
    for(i=0; aBucket[i]; i++){
      pEntry = rowSetMerge(aBucket[i], pEntry);
      aBucket[i] = 0;
    }
    aBucket[i] = pEntry;
  }
  pEntry = 0;
  for(i=0; i<sizeof(aBucket)/sizeof(aBucket[0]); i++){
    pEntry = rowSetMerge(pEntry, aBucket[i]);
  }
  p->pEntry = pEntry;
  p->pLast = 0;
  p->isSorted = 1;
}


/*
** The input, pIn, is a binary tree (or subtree) of RowSetEntry objects.
** Convert this tree into a linked list connected by the pRight pointers
** and return pointers to the first and last elements of the new list.
*/
static void rowSetTreeToList(
  struct RowSetEntry *pIn,         /* Root of the input tree */
  struct RowSetEntry **ppFirst,    /* Write head of the output list here */
  struct RowSetEntry **ppLast      /* Write tail of the output list here */
){
  assert( pIn!=0 );
  if( pIn->pLeft ){
    struct RowSetEntry *p;
    rowSetTreeToList(pIn->pLeft, ppFirst, &p);
    p->pRight = pIn;
  }else{
    *ppFirst = pIn;
  }
  if( pIn->pRight ){
    rowSetTreeToList(pIn->pRight, &pIn->pRight, ppLast);
  }else{
    *ppLast = pIn;
  }
  assert( (*ppLast)->pRight==0 );
}


/*
** Convert a sorted list of elements (connected by pRight) into a binary
** tree with depth of iDepth.  A depth of 1 means the tree contains a single
** node taken from the head of *ppList.  A depth of 2 means a tree with
** three nodes.  And so forth.
**
** Use as many entries from the input list as required and update the
** *ppList to point to the unused elements of the list.  If the input
** list contains too few elements, then construct an incomplete tree
** and leave *ppList set to NULL.
**
** Return a pointer to the root of the constructed binary tree.
*/
static struct RowSetEntry *rowSetNDeepTree(
  struct RowSetEntry **ppList,
  int iDepth
){
  struct RowSetEntry *p;         /* Root of the new tree */
  struct RowSetEntry *pLeft;     /* Left subtree */
  if( *ppList==0 ){
    return 0;
  }
  if( iDepth==1 ){
    p = *ppList;
    *ppList = p->pRight;
    p->pLeft = p->pRight = 0;
    return p;
  }
  pLeft = rowSetNDeepTree(ppList, iDepth-1);
  p = *ppList;
  if( p==0 ){
    return pLeft;
  }
  p->pLeft = pLeft;
  *ppList = p->pRight;
  p->pRight = rowSetNDeepTree(ppList, iDepth-1);
  return p;
}

/*
** Convert a sorted list of elements into a binary tree. Make the tree
** as deep as it needs to be in order to contain the entire list.
*/
static struct RowSetEntry *rowSetListToTree(struct RowSetEntry *pList){
  int iDepth;           /* Depth of the tree so far */
  struct RowSetEntry *p;       /* Current tree root */
  struct RowSetEntry *pLeft;   /* Left subtree */

  assert( pList!=0 );
  p = pList;
  pList = p->pRight;
  p->pLeft = p->pRight = 0;
  for(iDepth=1; pList; iDepth++){
    pLeft = p;
    p = pList;
    pList = p->pRight;
    p->pLeft = pLeft;
    p->pRight = rowSetNDeepTree(&pList, iDepth);
  }
  return p;
}

/*
** Convert the list in p->pEntry into a sorted list if it is not
** sorted already.  If there is a binary tree on p->pTree, then
** convert it into a list too and merge it into the p->pEntry list.
*/
static void rowSetToList(RowSet *p){
  if( !p->isSorted ){
    rowSetSort(p);
  }
  if( p->pTree ){
    struct RowSetEntry *pHead, *pTail;
    rowSetTreeToList(p->pTree, &pHead, &pTail);
    p->pTree = 0;
    p->pEntry = rowSetMerge(p->pEntry, pHead);
  }
}

/*
** Extract the smallest element from the RowSet.
** Write the element into *pRowid.  Return 1 on success.  Return
** 0 if the RowSet is already empty.
**
** After this routine has been called, the sqlite3RowSetInsert()
** routine may not be called again.
*/
SQLITE_PRIVATE int sqlite3RowSetNext(RowSet *p, i64 *pRowid){
  rowSetToList(p);
  if( p->pEntry ){
    *pRowid = p->pEntry->v;
    p->pEntry = p->pEntry->pRight;
    if( p->pEntry==0 ){
      sqlite3RowSetClear(p);
    }
    return 1;
  }else{
    return 0;
  }
}

/*
** Check to see if element iRowid was inserted into the the rowset as
** part of any insert batch prior to iBatch.  Return 1 or 0.
*/
SQLITE_PRIVATE int sqlite3RowSetTest(RowSet *pRowSet, u8 iBatch, sqlite3_int64 iRowid){
  struct RowSetEntry *p;
  if( iBatch!=pRowSet->iBatch ){
    if( pRowSet->pEntry ){
      rowSetToList(pRowSet);
      pRowSet->pTree = rowSetListToTree(pRowSet->pEntry);
      pRowSet->pEntry = 0;
      pRowSet->pLast = 0;
    }
    pRowSet->iBatch = iBatch;
  }
  p = pRowSet->pTree;
  while( p ){
    if( p->v<iRowid ){
      p = p->pRight;
    }else if( p->v>iRowid ){
      p = p->pLeft;
    }else{
      return 1;
    }
  }
  return 0;
}

/************** End of rowset.c **********************************************/
/************** Begin file pager.c *******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the implementation of the page cache subsystem or "pager".
**
** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
*/
#ifndef SQLITE_OMIT_DISKIO

/*
** Macros for troubleshooting.  Normally turned off
*/
#if 0
int sqlite3PagerTrace=1;  /* True to enable tracing */
#define sqlite3DebugPrintf printf
#define PAGERTRACE(X)     if( sqlite3PagerTrace ){ sqlite3DebugPrintf X; }
#else
#define PAGERTRACE(X)
#endif

/*
** The following two macros are used within the PAGERTRACE() macros above
** to print out file-descriptors.
**
** PAGERID() takes a pointer to a Pager struct as its argument. The
** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file
** struct as its argument.
*/
#define PAGERID(p) ((int)(p->fd))
#define FILEHANDLEID(fd) ((int)fd)

/*
** The page cache as a whole is always in one of the following
** states:
**
**   PAGER_UNLOCK        The page cache is not currently reading or
**                       writing the database file.  There is no
**                       data held in memory.  This is the initial
**                       state.
**
**   PAGER_SHARED        The page cache is reading the database.
**                       Writing is not permitted.  There can be
**                       multiple readers accessing the same database
**                       file at the same time.
**
**   PAGER_RESERVED      This process has reserved the database for writing
**                       but has not yet made any changes.  Only one process
**                       at a time can reserve the database.  The original
**                       database file has not been modified so other
**                       processes may still be reading the on-disk
**                       database file.
**
**   PAGER_EXCLUSIVE     The page cache is writing the database.
**                       Access is exclusive.  No other processes or
**                       threads can be reading or writing while one
**                       process is writing.
**
**   PAGER_SYNCED        The pager moves to this state from PAGER_EXCLUSIVE
**                       after all dirty pages have been written to the
**                       database file and the file has been synced to
**                       disk. All that remains to do is to remove or
**                       truncate the journal file and the transaction
**                       will be committed.
**
** The page cache comes up in PAGER_UNLOCK.  The first time a
** sqlite3PagerGet() occurs, the state transitions to PAGER_SHARED.
** After all pages have been released using sqlite_page_unref(),
** the state transitions back to PAGER_UNLOCK.  The first time
** that sqlite3PagerWrite() is called, the state transitions to
** PAGER_RESERVED.  (Note that sqlite3PagerWrite() can only be
** called on an outstanding page which means that the pager must
** be in PAGER_SHARED before it transitions to PAGER_RESERVED.)
** PAGER_RESERVED means that there is an open rollback journal.
** The transition to PAGER_EXCLUSIVE occurs before any changes
** are made to the database file, though writes to the rollback
** journal occurs with just PAGER_RESERVED.  After an sqlite3PagerRollback()
** or sqlite3PagerCommitPhaseTwo(), the state can go back to PAGER_SHARED,
** or it can stay at PAGER_EXCLUSIVE if we are in exclusive access mode.
*/
#define PAGER_UNLOCK      0
#define PAGER_SHARED      1   /* same as SHARED_LOCK */
#define PAGER_RESERVED    2   /* same as RESERVED_LOCK */
#define PAGER_EXCLUSIVE   4   /* same as EXCLUSIVE_LOCK */
#define PAGER_SYNCED      5

/*
** A macro used for invoking the codec if there is one
*/
#ifdef SQLITE_HAS_CODEC
# define CODEC1(P,D,N,X,E) \
    if( P->xCodec && P->xCodec(P->pCodec,D,N,X)==0 ){ E; }
# define CODEC2(P,D,N,X,E,O) \
    if( P->xCodec==0 ){ O=(char*)D; }else \
    if( (O=(char*)(P->xCodec(P->pCodec,D,N,X)))==0 ){ E; }
#else
# define CODEC1(P,D,N,X,E)   /* NO-OP */
# define CODEC2(P,D,N,X,E,O) O=(char*)D
#endif

/*
** The maximum allowed sector size. 64KiB. If the xSectorsize() method
** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
** This could conceivably cause corruption following a power failure on
** such a system. This is currently an undocumented limit.
*/
#define MAX_SECTOR_SIZE 0x10000

/*
** An instance of the following structure is allocated for each active
** savepoint and statement transaction in the system. All such structures
** are stored in the Pager.aSavepoint[] array, which is allocated and
** resized using sqlite3Realloc().
**
** When a savepoint is created, the PagerSavepoint.iHdrOffset field is
** set to 0. If a journal-header is written into the main journal while
** the savepoint is active, then iHdrOffset is set to the byte offset
** immediately following the last journal record written into the main
** journal before the journal-header. This is required during savepoint
** rollback (see pagerPlaybackSavepoint()).
*/
typedef struct PagerSavepoint PagerSavepoint;
struct PagerSavepoint {
  i64 iOffset;                 /* Starting offset in main journal */
  i64 iHdrOffset;              /* See above */
  Bitvec *pInSavepoint;        /* Set of pages in this savepoint */
  Pgno nOrig;                  /* Original number of pages in file */
  Pgno iSubRec;                /* Index of first record in sub-journal */
};

/*
** A open page cache is an instance of the following structure.
**
** errCode
**
**   Pager.errCode may be set to SQLITE_IOERR, SQLITE_CORRUPT, or
**   or SQLITE_FULL. Once one of the first three errors occurs, it persists
**   and is returned as the result of every major pager API call.  The
**   SQLITE_FULL return code is slightly different. It persists only until the
**   next successful rollback is performed on the pager cache. Also,
**   SQLITE_FULL does not affect the sqlite3PagerGet() and sqlite3PagerLookup()
**   APIs, they may still be used successfully.
**
** dbSizeValid, dbSize, dbOrigSize, dbFileSize
**
**   Managing the size of the database file in pages is a little complicated.
**   The variable Pager.dbSize contains the number of pages that the database
**   image currently contains. As the database image grows or shrinks this
**   variable is updated. The variable Pager.dbFileSize contains the number
**   of pages in the database file. This may be different from Pager.dbSize
**   if some pages have been appended to the database image but not yet written
**   out from the cache to the actual file on disk. Or if the image has been
**   truncated by an incremental-vacuum operation. The Pager.dbOrigSize variable
**   contains the number of pages in the database image when the current
**   transaction was opened. The contents of all three of these variables is
**   only guaranteed to be correct if the boolean Pager.dbSizeValid is true.
**
**   TODO: Under what conditions is dbSizeValid set? Cleared?
**
** changeCountDone
**
**   This boolean variable is used to make sure that the change-counter
**   (the 4-byte header field at byte offset 24 of the database file) is
**   not updated more often than necessary.
**
**   It is set to true when the change-counter field is updated, which
**   can only happen if an exclusive lock is held on the database file.
**   It is cleared (set to false) whenever an exclusive lock is
**   relinquished on the database file. Each time a transaction is committed,
**   The changeCountDone flag is inspected. If it is true, the work of
**   updating the change-counter is omitted for the current transaction.
**
**   This mechanism means that when running in exclusive mode, a connection
**   need only update the change-counter once, for the first transaction
**   committed.
**
** dbModified
**
**   The dbModified flag is set whenever a database page is dirtied.
**   It is cleared at the end of each transaction.
**
**   It is used when committing or otherwise ending a transaction. If
**   the dbModified flag is clear then less work has to be done.
**
** journalStarted
**
**   This flag is set whenever the the main journal is synced.
**
**   The point of this flag is that it must be set after the
**   first journal header in a journal file has been synced to disk.
**   After this has happened, new pages appended to the database
**   do not need the PGHDR_NEED_SYNC flag set, as they do not need
**   to wait for a journal sync before they can be written out to
**   the database file (see function pager_write()).
**
** setMaster
**
**   This variable is used to ensure that the master journal file name
**   (if any) is only written into the journal file once.
**
**   When committing a transaction, the master journal file name (if any)
**   may be written into the journal file while the pager is still in
**   PAGER_RESERVED state (see CommitPhaseOne() for the action). It
**   then attempts to upgrade to an exclusive lock. If this attempt
**   fails, then SQLITE_BUSY may be returned to the user and the user
**   may attempt to commit the transaction again later (calling
**   CommitPhaseOne() again). This flag is used to ensure that the
**   master journal name is only written to the journal file the first
**   time CommitPhaseOne() is called.
**
** doNotSync
**
**   This variable is set and cleared by sqlite3PagerWrite().
**
** needSync
**
**   TODO: It might be easier to set this variable in writeJournalHdr()
**   and writeMasterJournal() only. Change its meaning to "unsynced data
**   has been written to the journal".
**
** subjInMemory
**
**   This is a boolean variable. If true, then any required sub-journal
**   is opened as an in-memory journal file. If false, then in-memory
**   sub-journals are only used for in-memory pager files.
*/
struct Pager {
  sqlite3_vfs *pVfs;          /* OS functions to use for IO */
  u8 exclusiveMode;           /* Boolean. True if locking_mode==EXCLUSIVE */
  u8 journalMode;             /* On of the PAGER_JOURNALMODE_* values */
  u8 useJournal;              /* Use a rollback journal on this file */
  u8 noReadlock;              /* Do not bother to obtain readlocks */
  u8 noSync;                  /* Do not sync the journal if true */
  u8 fullSync;                /* Do extra syncs of the journal for robustness */
  u8 sync_flags;              /* One of SYNC_NORMAL or SYNC_FULL */
  u8 tempFile;                /* zFilename is a temporary file */
  u8 readOnly;                /* True for a read-only database */
  u8 memDb;                   /* True to inhibit all file I/O */

  /* The following block contains those class members that are dynamically
  ** modified during normal operations. The other variables in this structure
  ** are either constant throughout the lifetime of the pager, or else
  ** used to store configuration parameters that affect the way the pager
  ** operates.
  **
  ** The 'state' variable is described in more detail along with the
  ** descriptions of the values it may take - PAGER_UNLOCK etc. Many of the
  ** other variables in this block are described in the comment directly
  ** above this class definition.
  */
  u8 state;                   /* PAGER_UNLOCK, _SHARED, _RESERVED, etc. */
  u8 dbModified;              /* True if there are any changes to the Db */
  u8 needSync;                /* True if an fsync() is needed on the journal */
  u8 journalStarted;          /* True if header of journal is synced */
  u8 changeCountDone;         /* Set after incrementing the change-counter */
  u8 setMaster;               /* True if a m-j name has been written to jrnl */
  u8 doNotSync;               /* Boolean. While true, do not spill the cache */
  u8 dbSizeValid;             /* Set when dbSize is correct */
  u8 subjInMemory;            /* True to use in-memory sub-journals */
  Pgno dbSize;                /* Number of pages in the database */
  Pgno dbOrigSize;            /* dbSize before the current transaction */
  Pgno dbFileSize;            /* Number of pages in the database file */
  int errCode;                /* One of several kinds of errors */
  int nRec;                   /* Pages journalled since last j-header written */
  u32 cksumInit;              /* Quasi-random value added to every checksum */
  u32 nSubRec;                /* Number of records written to sub-journal */
  Bitvec *pInJournal;         /* One bit for each page in the database file */
  sqlite3_file *fd;           /* File descriptor for database */
  sqlite3_file *jfd;          /* File descriptor for main journal */
  sqlite3_file *sjfd;         /* File descriptor for sub-journal */
  i64 journalOff;             /* Current write offset in the journal file */
  i64 journalHdr;             /* Byte offset to previous journal header */
  PagerSavepoint *aSavepoint; /* Array of active savepoints */
  int nSavepoint;             /* Number of elements in aSavepoint[] */
  char dbFileVers[16];        /* Changes whenever database file changes */
  u32 sectorSize;             /* Assumed sector size during rollback */

  u16 nExtra;                 /* Add this many bytes to each in-memory page */
  i16 nReserve;               /* Number of unused bytes at end of each page */
  u32 vfsFlags;               /* Flags for sqlite3_vfs.xOpen() */
  int pageSize;               /* Number of bytes in a page */
  Pgno mxPgno;                /* Maximum allowed size of the database */
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
  int (*xBusyHandler)(void*); /* Function to call when busy */
  void *pBusyHandlerArg;      /* Context argument for xBusyHandler */
#ifdef SQLITE_TEST
  int nHit, nMiss;            /* Cache hits and missing */
  int nRead, nWrite;          /* Database pages read/written */
#endif
  void (*xReiniter)(DbPage*); /* Call this routine when reloading pages */
#ifdef SQLITE_HAS_CODEC
  void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
  void (*xCodecSizeChng)(void*,int,int); /* Notify of page size changes */
  void (*xCodecFree)(void*);             /* Destructor for the codec */
  void *pCodec;               /* First argument to xCodec... methods */
#endif
  char *pTmpSpace;            /* Pager.pageSize bytes of space for tmp use */
  i64 journalSizeLimit;       /* Size limit for persistent journal files */
  PCache *pPCache;            /* Pointer to page cache object */
  sqlite3_backup *pBackup;    /* Pointer to list of ongoing backup processes */
};

/*
** The following global variables hold counters used for
** testing purposes only.  These variables do not exist in
** a non-testing build.  These variables are not thread-safe.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_pager_readdb_count = 0;    /* Number of full pages read from DB */
SQLITE_API int sqlite3_pager_writedb_count = 0;   /* Number of full pages written to DB */
SQLITE_API int sqlite3_pager_writej_count = 0;    /* Number of pages written to journal */
# define PAGER_INCR(v)  v++
#else
# define PAGER_INCR(v)
#endif



/*
** Journal files begin with the following magic string.  The data
** was obtained from /dev/random.  It is used only as a sanity check.
**
** Since version 2.8.0, the journal format contains additional sanity
** checking information.  If the power fails while the journal is being
** written, semi-random garbage data might appear in the journal
** file after power is restored.  If an attempt is then made
** to roll the journal back, the database could be corrupted.  The additional
** sanity checking data is an attempt to discover the garbage in the
** journal and ignore it.
**
** The sanity checking information for the new journal format consists
** of a 32-bit checksum on each page of data.  The checksum covers both
** the page number and the pPager->pageSize bytes of data for the page.
** This cksum is initialized to a 32-bit random value that appears in the
** journal file right after the header.  The random initializer is important,
** because garbage data that appears at the end of a journal is likely
** data that was once in other files that have now been deleted.  If the
** garbage data came from an obsolete journal file, the checksums might
** be correct.  But by initializing the checksum to random value which
** is different for every journal, we minimize that risk.
*/
static const unsigned char aJournalMagic[] = {
  0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7,
};

/*
** The size of the of each page record in the journal is given by
** the following macro.
*/
#define JOURNAL_PG_SZ(pPager)  ((pPager->pageSize) + 8)

/*
** The journal header size for this pager. This is usually the same
** size as a single disk sector. See also setSectorSize().
*/
#define JOURNAL_HDR_SZ(pPager) (pPager->sectorSize)

/*
** The macro MEMDB is true if we are dealing with an in-memory database.
** We do this as a macro so that if the SQLITE_OMIT_MEMORYDB macro is set,
** the value of MEMDB will be a constant and the compiler will optimize
** out code that would never execute.
*/
#ifdef SQLITE_OMIT_MEMORYDB
# define MEMDB 0
#else
# define MEMDB pPager->memDb
#endif

/*
** The maximum legal page number is (2^31 - 1).
*/
#define PAGER_MAX_PGNO 2147483647

#ifndef NDEBUG
/*
** Usage:
**
**   assert( assert_pager_state(pPager) );
*/
static int assert_pager_state(Pager *pPager){

  /* A temp-file is always in PAGER_EXCLUSIVE or PAGER_SYNCED state. */
  assert( pPager->tempFile==0 || pPager->state>=PAGER_EXCLUSIVE );

  /* The changeCountDone flag is always set for temp-files */
  assert( pPager->tempFile==0 || pPager->changeCountDone );

  return 1;
}
#endif

/*
** Return true if it is necessary to write page *pPg into the sub-journal.
** A page needs to be written into the sub-journal if there exists one
** or more open savepoints for which:
**
**   * The page-number is less than or equal to PagerSavepoint.nOrig, and
**   * The bit corresponding to the page-number is not set in
**     PagerSavepoint.pInSavepoint.
*/
static int subjRequiresPage(PgHdr *pPg){
  Pgno pgno = pPg->pgno;
  Pager *pPager = pPg->pPager;
  int i;
  for(i=0; i<pPager->nSavepoint; i++){
    PagerSavepoint *p = &pPager->aSavepoint[i];
    if( p->nOrig>=pgno && 0==sqlite3BitvecTest(p->pInSavepoint, pgno) ){
      return 1;
    }
  }
  return 0;
}

/*
** Return true if the page is already in the journal file.
*/
static int pageInJournal(PgHdr *pPg){
  return sqlite3BitvecTest(pPg->pPager->pInJournal, pPg->pgno);
}

/*
** Read a 32-bit integer from the given file descriptor.  Store the integer
** that is read in *pRes.  Return SQLITE_OK if everything worked, or an
** error code is something goes wrong.
**
** All values are stored on disk as big-endian.
*/
static int read32bits(sqlite3_file *fd, i64 offset, u32 *pRes){
  unsigned char ac[4];
  int rc = sqlite3OsRead(fd, ac, sizeof(ac), offset);
  if( rc==SQLITE_OK ){
    *pRes = sqlite3Get4byte(ac);
  }
  return rc;
}

/*
** Write a 32-bit integer into a string buffer in big-endian byte order.
*/
#define put32bits(A,B)  sqlite3Put4byte((u8*)A,B)

/*
** Write a 32-bit integer into the given file descriptor.  Return SQLITE_OK
** on success or an error code is something goes wrong.
*/
static int write32bits(sqlite3_file *fd, i64 offset, u32 val){
  char ac[4];
  put32bits(ac, val);
  return sqlite3OsWrite(fd, ac, 4, offset);
}

/*
** The argument to this macro is a file descriptor (type sqlite3_file*).
** Return 0 if it is not open, or non-zero (but not 1) if it is.
**
** This is so that expressions can be written as:
**
**   if( isOpen(pPager->jfd) ){ ...
**
** instead of
**
**   if( pPager->jfd->pMethods ){ ...
*/
#define isOpen(pFd) ((pFd)->pMethods)

/*
** If file pFd is open, call sqlite3OsUnlock() on it.
*/
static int osUnlock(sqlite3_file *pFd, int eLock){
  if( !isOpen(pFd) ){
    return SQLITE_OK;
  }
  return sqlite3OsUnlock(pFd, eLock);
}

/*
** This function determines whether or not the atomic-write optimization
** can be used with this pager. The optimization can be used if:
**
**  (a) the value returned by OsDeviceCharacteristics() indicates that
**      a database page may be written atomically, and
**  (b) the value returned by OsSectorSize() is less than or equal
**      to the page size.
**
** The optimization is also always enabled for temporary files. It is
** an error to call this function if pPager is opened on an in-memory
** database.
**
** If the optimization cannot be used, 0 is returned. If it can be used,
** then the value returned is the size of the journal file when it
** contains rollback data for exactly one page.
*/
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
static int jrnlBufferSize(Pager *pPager){
  assert( !MEMDB );
  if( !pPager->tempFile ){
    int dc;                           /* Device characteristics */
    int nSector;                      /* Sector size */
    int szPage;                       /* Page size */

    assert( isOpen(pPager->fd) );
    dc = sqlite3OsDeviceCharacteristics(pPager->fd);
    nSector = pPager->sectorSize;
    szPage = pPager->pageSize;

    assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
    assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
    if( 0==(dc&(SQLITE_IOCAP_ATOMIC|(szPage>>8)) || nSector>szPage) ){
      return 0;
    }
  }

  return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
}
#endif

/*
** If SQLITE_CHECK_PAGES is defined then we do some sanity checking
** on the cache using a hash function.  This is used for testing
** and debugging only.
*/
#ifdef SQLITE_CHECK_PAGES
/*
** Return a 32-bit hash of the page data for pPage.
*/
static u32 pager_datahash(int nByte, unsigned char *pData){
  u32 hash = 0;
  int i;
  for(i=0; i<nByte; i++){
    hash = (hash*1039) + pData[i];
  }
  return hash;
}
static u32 pager_pagehash(PgHdr *pPage){
  return pager_datahash(pPage->pPager->pageSize, (unsigned char *)pPage->pData);
}
static void pager_set_pagehash(PgHdr *pPage){
  pPage->pageHash = pager_pagehash(pPage);
}

/*
** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES
** is defined, and NDEBUG is not defined, an assert() statement checks
** that the page is either dirty or still matches the calculated page-hash.
*/
#define CHECK_PAGE(x) checkPage(x)
static void checkPage(PgHdr *pPg){
  Pager *pPager = pPg->pPager;
  assert( !pPg->pageHash || pPager->errCode
      || (pPg->flags&PGHDR_DIRTY) || pPg->pageHash==pager_pagehash(pPg) );
}

#else
#define pager_datahash(X,Y)  0
#define pager_pagehash(X)  0
#define CHECK_PAGE(x)
#endif  /* SQLITE_CHECK_PAGES */

/*
** When this is called the journal file for pager pPager must be open.
** This function attempts to read a master journal file name from the
** end of the file and, if successful, copies it into memory supplied
** by the caller. See comments above writeMasterJournal() for the format
** used to store a master journal file name at the end of a journal file.
**
** zMaster must point to a buffer of at least nMaster bytes allocated by
** the caller. This should be sqlite3_vfs.mxPathname+1 (to ensure there is
** enough space to write the master journal name). If the master journal
** name in the journal is longer than nMaster bytes (including a
** nul-terminator), then this is handled as if no master journal name
** were present in the journal.
**
** If a master journal file name is present at the end of the journal
** file, then it is copied into the buffer pointed to by zMaster. A
** nul-terminator byte is appended to the buffer following the master
** journal file name.
**
** If it is determined that no master journal file name is present
** zMaster[0] is set to 0 and SQLITE_OK returned.
**
** If an error occurs while reading from the journal file, an SQLite
** error code is returned.
*/
static int readMasterJournal(sqlite3_file *pJrnl, char *zMaster, u32 nMaster){
  int rc;                    /* Return code */
  u32 len;                   /* Length in bytes of master journal name */
  i64 szJ;                   /* Total size in bytes of journal file pJrnl */
  u32 cksum;                 /* MJ checksum value read from journal */
  u32 u;                     /* Unsigned loop counter */
  unsigned char aMagic[8];   /* A buffer to hold the magic header */
  zMaster[0] = '\0';

  if( SQLITE_OK!=(rc = sqlite3OsFileSize(pJrnl, &szJ))
   || szJ<16
   || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-16, &len))
   || len>=nMaster
   || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-12, &cksum))
   || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8))
   || memcmp(aMagic, aJournalMagic, 8)
   || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, zMaster, len, szJ-16-len))
  ){
    return rc;
  }

  /* See if the checksum matches the master journal name */
  for(u=0; u<len; u++){
    cksum -= zMaster[u];
  }
  if( cksum ){
    /* If the checksum doesn't add up, then one or more of the disk sectors
    ** containing the master journal filename is corrupted. This means
    ** definitely roll back, so just return SQLITE_OK and report a (nul)
    ** master-journal filename.
    */
    len = 0;
  }
  zMaster[len] = '\0';

  return SQLITE_OK;
}

/*
** Return the offset of the sector boundary at or immediately
** following the value in pPager->journalOff, assuming a sector
** size of pPager->sectorSize bytes.
**
** i.e for a sector size of 512:
**
**   Pager.journalOff          Return value
**   ---------------------------------------
**   0                         0
**   512                       512
**   100                       512
**   2000                      2048
**
*/
static i64 journalHdrOffset(Pager *pPager){
  i64 offset = 0;
  i64 c = pPager->journalOff;
  if( c ){
    offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
  }
  assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
  assert( offset>=c );
  assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
  return offset;
}

/*
** The journal file must be open when this function is called.
**
** This function is a no-op if the journal file has not been written to
** within the current transaction (i.e. if Pager.journalOff==0).
**
** If doTruncate is non-zero or the Pager.journalSizeLimit variable is
** set to 0, then truncate the journal file to zero bytes in size. Otherwise,
** zero the 28-byte header at the start of the journal file. In either case,
** if the pager is not in no-sync mode, sync the journal file immediately
** after writing or truncating it.
**
** If Pager.journalSizeLimit is set to a positive, non-zero value, and
** following the truncation or zeroing described above the size of the
** journal file in bytes is larger than this value, then truncate the
** journal file to Pager.journalSizeLimit bytes. The journal file does
** not need to be synced following this operation.
**
** If an IO error occurs, abandon processing and return the IO error code.
** Otherwise, return SQLITE_OK.
*/
static int zeroJournalHdr(Pager *pPager, int doTruncate){
  int rc = SQLITE_OK;                               /* Return code */
  assert( isOpen(pPager->jfd) );
  if( pPager->journalOff ){
    const i64 iLimit = pPager->journalSizeLimit;    /* Local cache of jsl */

    IOTRACE(("JZEROHDR %p\n", pPager))
    if( doTruncate || iLimit==0 ){
      rc = sqlite3OsTruncate(pPager->jfd, 0);
    }else{
      static const char zeroHdr[28] = {0};
      rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0);
    }
    if( rc==SQLITE_OK && !pPager->noSync ){
      rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_DATAONLY|pPager->sync_flags);
    }

    /* At this point the transaction is committed but the write lock
    ** is still held on the file. If there is a size limit configured for
    ** the persistent journal and the journal file currently consumes more
    ** space than that limit allows for, truncate it now. There is no need
    ** to sync the file following this operation.
    */
    if( rc==SQLITE_OK && iLimit>0 ){
      i64 sz;
      rc = sqlite3OsFileSize(pPager->jfd, &sz);
      if( rc==SQLITE_OK && sz>iLimit ){
        rc = sqlite3OsTruncate(pPager->jfd, iLimit);
      }
    }
  }
  return rc;
}

/*
** The journal file must be open when this routine is called. A journal
** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
** current location.
**
** The format for the journal header is as follows:
** - 8 bytes: Magic identifying journal format.
** - 4 bytes: Number of records in journal, or -1 no-sync mode is on.
** - 4 bytes: Random number used for page hash.
** - 4 bytes: Initial database page count.
** - 4 bytes: Sector size used by the process that wrote this journal.
** - 4 bytes: Database page size.
**
** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space.
*/
static int writeJournalHdr(Pager *pPager){
  int rc = SQLITE_OK;                 /* Return code */
  char *zHeader = pPager->pTmpSpace;  /* Temporary space used to build header */
  u32 nHeader = pPager->pageSize;     /* Size of buffer pointed to by zHeader */
  u32 nWrite;                         /* Bytes of header sector written */
  int ii;                             /* Loop counter */

  assert( isOpen(pPager->jfd) );      /* Journal file must be open. */

  if( nHeader>JOURNAL_HDR_SZ(pPager) ){
    nHeader = JOURNAL_HDR_SZ(pPager);
  }

  /* If there are active savepoints and any of them were created
  ** since the most recent journal header was written, update the
  ** PagerSavepoint.iHdrOffset fields now.
  */
  for(ii=0; ii<pPager->nSavepoint; ii++){
    if( pPager->aSavepoint[ii].iHdrOffset==0 ){
      pPager->aSavepoint[ii].iHdrOffset = pPager->journalOff;
    }
  }

  pPager->journalHdr = pPager->journalOff = journalHdrOffset(pPager);

  /*
  ** Write the nRec Field - the number of page records that follow this
  ** journal header. Normally, zero is written to this value at this time.
  ** After the records are added to the journal (and the journal synced,
  ** if in full-sync mode), the zero is overwritten with the true number
  ** of records (see syncJournal()).
  **
  ** A faster alternative is to write 0xFFFFFFFF to the nRec field. When
  ** reading the journal this value tells SQLite to assume that the
  ** rest of the journal file contains valid page records. This assumption
  ** is dangerous, as if a failure occurred whilst writing to the journal
  ** file it may contain some garbage data. There are two scenarios
  ** where this risk can be ignored:
  **
  **   * When the pager is in no-sync mode. Corruption can follow a
  **     power failure in this case anyway.
  **
  **   * When the SQLITE_IOCAP_SAFE_APPEND flag is set. This guarantees
  **     that garbage data is never appended to the journal file.
  */
  assert( isOpen(pPager->fd) || pPager->noSync );
  if( (pPager->noSync) || (pPager->journalMode==PAGER_JOURNALMODE_MEMORY)
   || (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND)
  ){
    memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
    put32bits(&zHeader[sizeof(aJournalMagic)], 0xffffffff);
  }else{
    memset(zHeader, 0, sizeof(aJournalMagic)+4);
  }

  /* The random check-hash initialiser */
  sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
  put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
  /* The initial database size */
  put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbOrigSize);
  /* The assumed sector size for this process */
  put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);

  /* The page size */
  put32bits(&zHeader[sizeof(aJournalMagic)+16], pPager->pageSize);

  /* Initializing the tail of the buffer is not necessary.  Everything
  ** works find if the following memset() is omitted.  But initializing
  ** the memory prevents valgrind from complaining, so we are willing to
  ** take the performance hit.
  */
  memset(&zHeader[sizeof(aJournalMagic)+20], 0,
         nHeader-(sizeof(aJournalMagic)+20));

  /* In theory, it is only necessary to write the 28 bytes that the
  ** journal header consumes to the journal file here. Then increment the
  ** Pager.journalOff variable by JOURNAL_HDR_SZ so that the next
  ** record is written to the following sector (leaving a gap in the file
  ** that will be implicitly filled in by the OS).
  **
  ** However it has been discovered that on some systems this pattern can
  ** be significantly slower than contiguously writing data to the file,
  ** even if that means explicitly writing data to the block of
  ** (JOURNAL_HDR_SZ - 28) bytes that will not be used. So that is what
  ** is done.
  **
  ** The loop is required here in case the sector-size is larger than the
  ** database page size. Since the zHeader buffer is only Pager.pageSize
  ** bytes in size, more than one call to sqlite3OsWrite() may be required
  ** to populate the entire journal header sector.
  */
  for(nWrite=0; rc==SQLITE_OK&&nWrite<JOURNAL_HDR_SZ(pPager); nWrite+=nHeader){
    IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, nHeader))
    rc = sqlite3OsWrite(pPager->jfd, zHeader, nHeader, pPager->journalOff);
    pPager->journalOff += nHeader;
  }

  return rc;
}

/*
** The journal file must be open when this is called. A journal header file
** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal
** file. The current location in the journal file is given by
** pPager->journalOff. See comments above function writeJournalHdr() for
** a description of the journal header format.
**
** If the header is read successfully, *pNRec is set to the number of
** page records following this header and *pDbSize is set to the size of the
** database before the transaction began, in pages. Also, pPager->cksumInit
** is set to the value read from the journal header. SQLITE_OK is returned
** in this case.
**
** If the journal header file appears to be corrupted, SQLITE_DONE is
** returned and *pNRec and *PDbSize are undefined.  If JOURNAL_HDR_SZ bytes
** cannot be read from the journal file an error code is returned.
*/
static int readJournalHdr(
  Pager *pPager,               /* Pager object */
  int isHot,
  i64 journalSize,             /* Size of the open journal file in bytes */
  u32 *pNRec,                  /* OUT: Value read from the nRec field */
  u32 *pDbSize                 /* OUT: Value of original database size field */
){
  int rc;                      /* Return code */
  unsigned char aMagic[8];     /* A buffer to hold the magic header */
  i64 iHdrOff;                 /* Offset of journal header being read */

  assert( isOpen(pPager->jfd) );      /* Journal file must be open. */

  /* Advance Pager.journalOff to the start of the next sector. If the
  ** journal file is too small for there to be a header stored at this
  ** point, return SQLITE_DONE.
  */
  pPager->journalOff = journalHdrOffset(pPager);
  if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
    return SQLITE_DONE;
  }
  iHdrOff = pPager->journalOff;

  /* Read in the first 8 bytes of the journal header. If they do not match
  ** the  magic string found at the start of each journal header, return
  ** SQLITE_DONE. If an IO error occurs, return an error code. Otherwise,
  ** proceed.
  */
  if( isHot || iHdrOff!=pPager->journalHdr ){
    rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), iHdrOff);
    if( rc ){
      return rc;
    }
    if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
      return SQLITE_DONE;
    }
  }

  /* Read the first three 32-bit fields of the journal header: The nRec
  ** field, the checksum-initializer and the database size at the start
  ** of the transaction. Return an error code if anything goes wrong.
  */
  if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+8, pNRec))
   || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+12, &pPager->cksumInit))
   || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+16, pDbSize))
  ){
    return rc;
  }

  if( pPager->journalOff==0 ){
    u32 iPageSize;               /* Page-size field of journal header */
    u32 iSectorSize;             /* Sector-size field of journal header */
    u16 iPageSize16;             /* Copy of iPageSize in 16-bit variable */

    /* Read the page-size and sector-size journal header fields. */
    if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+20, &iSectorSize))
     || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+24, &iPageSize))
    ){
      return rc;
    }

    /* Check that the values read from the page-size and sector-size fields
    ** are within range. To be 'in range', both values need to be a power
    ** of two greater than or equal to 512 or 32, and not greater than their
    ** respective compile time maximum limits.
    */
    if( iPageSize<512                  || iSectorSize<32
     || iPageSize>SQLITE_MAX_PAGE_SIZE || iSectorSize>MAX_SECTOR_SIZE
     || ((iPageSize-1)&iPageSize)!=0   || ((iSectorSize-1)&iSectorSize)!=0
    ){
      /* If the either the page-size or sector-size in the journal-header is
      ** invalid, then the process that wrote the journal-header must have
      ** crashed before the header was synced. In this case stop reading
      ** the journal file here.
      */
      return SQLITE_DONE;
    }

    /* Update the page-size to match the value read from the journal.
    ** Use a testcase() macro to make sure that malloc failure within
    ** PagerSetPagesize() is tested.
    */
    iPageSize16 = (u16)iPageSize;
    rc = sqlite3PagerSetPagesize(pPager, &iPageSize16, -1);
    testcase( rc!=SQLITE_OK );
    assert( rc!=SQLITE_OK || iPageSize16==(u16)iPageSize );

    /* Update the assumed sector-size to match the value used by
    ** the process that created this journal. If this journal was
    ** created by a process other than this one, then this routine
    ** is being called from within pager_playback(). The local value
    ** of Pager.sectorSize is restored at the end of that routine.
    */
    pPager->sectorSize = iSectorSize;
  }

  pPager->journalOff += JOURNAL_HDR_SZ(pPager);
  return rc;
}


/*
** Write the supplied master journal name into the journal file for pager
** pPager at the current location. The master journal name must be the last
** thing written to a journal file. If the pager is in full-sync mode, the
** journal file descriptor is advanced to the next sector boundary before
** anything is written. The format is:
**
**   + 4 bytes: PAGER_MJ_PGNO.
**   + N bytes: Master journal filename in utf-8.
**   + 4 bytes: N (length of master journal name in bytes, no nul-terminator).
**   + 4 bytes: Master journal name checksum.
**   + 8 bytes: aJournalMagic[].
**
** The master journal page checksum is the sum of the bytes in the master
** journal name, where each byte is interpreted as a signed 8-bit integer.
**
** If zMaster is a NULL pointer (occurs for a single database transaction),
** this call is a no-op.
*/
static int writeMasterJournal(Pager *pPager, const char *zMaster){
  int rc;                          /* Return code */
  int nMaster;                     /* Length of string zMaster */
  i64 iHdrOff;                     /* Offset of header in journal file */
  i64 jrnlSize;                    /* Size of journal file on disk */
  u32 cksum = 0;                   /* Checksum of string zMaster */

  if( !zMaster || pPager->setMaster
   || pPager->journalMode==PAGER_JOURNALMODE_MEMORY
   || pPager->journalMode==PAGER_JOURNALMODE_OFF
  ){
    return SQLITE_OK;
  }
  pPager->setMaster = 1;
  assert( isOpen(pPager->jfd) );

  /* Calculate the length in bytes and the checksum of zMaster */
  for(nMaster=0; zMaster[nMaster]; nMaster++){
    cksum += zMaster[nMaster];
  }

  /* If in full-sync mode, advance to the next disk sector before writing
  ** the master journal name. This is in case the previous page written to
  ** the journal has already been synced.
  */
  if( pPager->fullSync ){
    pPager->journalOff = journalHdrOffset(pPager);
  }
  iHdrOff = pPager->journalOff;

  /* Write the master journal data to the end of the journal file. If
  ** an error occurs, return the error code to the caller.
  */
  if( (0 != (rc = write32bits(pPager->jfd, iHdrOff, PAGER_MJ_PGNO(pPager))))
   || (0 != (rc = sqlite3OsWrite(pPager->jfd, zMaster, nMaster, iHdrOff+4)))
   || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster, nMaster)))
   || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster+4, cksum)))
   || (0 != (rc = sqlite3OsWrite(pPager->jfd, aJournalMagic, 8, iHdrOff+4+nMaster+8)))
  ){
    return rc;
  }
  pPager->journalOff += (nMaster+20);
  pPager->needSync = !pPager->noSync;

  /* If the pager is in peristent-journal mode, then the physical
  ** journal-file may extend past the end of the master-journal name
  ** and 8 bytes of magic data just written to the file. This is
  ** dangerous because the code to rollback a hot-journal file
  ** will not be able to find the master-journal name to determine
  ** whether or not the journal is hot.
  **
  ** Easiest thing to do in this scenario is to truncate the journal
  ** file to the required size.
  */
  if( SQLITE_OK==(rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))
   && jrnlSize>pPager->journalOff
  ){
    rc = sqlite3OsTruncate(pPager->jfd, pPager->journalOff);
  }
  return rc;
}

/*
** Find a page in the hash table given its page number. Return
** a pointer to the page or NULL if the requested page is not
** already in memory.
*/
static PgHdr *pager_lookup(Pager *pPager, Pgno pgno){
  PgHdr *p;                         /* Return value */

  /* It is not possible for a call to PcacheFetch() with createFlag==0 to
  ** fail, since no attempt to allocate dynamic memory will be made.
  */
  (void)sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &p);
  return p;
}

/*
** Unless the pager is in error-state, discard all in-memory pages. If
** the pager is in error-state, then this call is a no-op.
**
** TODO: Why can we not reset the pager while in error state?
*/
static void pager_reset(Pager *pPager){
  if( SQLITE_OK==pPager->errCode ){
    sqlite3BackupRestart(pPager->pBackup);
    sqlite3PcacheClear(pPager->pPCache);
    pPager->dbSizeValid = 0;
  }
}

/*
** Free all structures in the Pager.aSavepoint[] array and set both
** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
** if it is open and the pager is not in exclusive mode.
*/
static void releaseAllSavepoints(Pager *pPager){
  int ii;               /* Iterator for looping through Pager.aSavepoint */
  for(ii=0; ii<pPager->nSavepoint; ii++){
    sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
  }
  if( !pPager->exclusiveMode || sqlite3IsMemJournal(pPager->sjfd) ){
    sqlite3OsClose(pPager->sjfd);
  }
  sqlite3_free(pPager->aSavepoint);
  pPager->aSavepoint = 0;
  pPager->nSavepoint = 0;
  pPager->nSubRec = 0;
}

/*
** Set the bit number pgno in the PagerSavepoint.pInSavepoint
** bitvecs of all open savepoints. Return SQLITE_OK if successful
** or SQLITE_NOMEM if a malloc failure occurs.
*/
static int addToSavepointBitvecs(Pager *pPager, Pgno pgno){
  int ii;                   /* Loop counter */
  int rc = SQLITE_OK;       /* Result code */

  for(ii=0; ii<pPager->nSavepoint; ii++){
    PagerSavepoint *p = &pPager->aSavepoint[ii];
    if( pgno<=p->nOrig ){
      rc |= sqlite3BitvecSet(p->pInSavepoint, pgno);
      testcase( rc==SQLITE_NOMEM );
      assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
    }
  }
  return rc;
}

/*
** Unlock the database file. This function is a no-op if the pager
** is in exclusive mode.
**
** If the pager is currently in error state, discard the contents of
** the cache and reset the Pager structure internal state. If there is
** an open journal-file, then the next time a shared-lock is obtained
** on the pager file (by this or any other process), it will be
** treated as a hot-journal and rolled back.
*/
static void pager_unlock(Pager *pPager){
  if( !pPager->exclusiveMode ){
    int rc;                      /* Return code */

    /* Always close the journal file when dropping the database lock.
    ** Otherwise, another connection with journal_mode=delete might
    ** delete the file out from under us.
    */
    sqlite3OsClose(pPager->jfd);
    sqlite3BitvecDestroy(pPager->pInJournal);
    pPager->pInJournal = 0;
    releaseAllSavepoints(pPager);

    /* If the file is unlocked, somebody else might change it. The
    ** values stored in Pager.dbSize etc. might become invalid if
    ** this happens. TODO: Really, this doesn't need to be cleared
    ** until the change-counter check fails in PagerSharedLock().
    */
    pPager->dbSizeValid = 0;

    rc = osUnlock(pPager->fd, NO_LOCK);
    if( rc ){
      pPager->errCode = rc;
    }
    IOTRACE(("UNLOCK %p\n", pPager))

    /* If Pager.errCode is set, the contents of the pager cache cannot be
    ** trusted. Now that the pager file is unlocked, the contents of the
    ** cache can be discarded and the error code safely cleared.
    */
    if( pPager->errCode ){
      if( rc==SQLITE_OK ){
        pPager->errCode = SQLITE_OK;
      }
      pager_reset(pPager);
    }

    pPager->changeCountDone = 0;
    pPager->state = PAGER_UNLOCK;
    pPager->dbModified = 0;
  }
}

/*
** This function should be called when an IOERR, CORRUPT or FULL error
** may have occurred. The first argument is a pointer to the pager
** structure, the second the error-code about to be returned by a pager
** API function. The value returned is a copy of the second argument
** to this function.
**
** If the second argument is SQLITE_IOERR, SQLITE_CORRUPT, or SQLITE_FULL
** the error becomes persistent. Until the persisten error is cleared,
** subsequent API calls on this Pager will immediately return the same
** error code.
**
** A persistent error indicates that the contents of the pager-cache
** cannot be trusted. This state can be cleared by completely discarding
** the contents of the pager-cache. If a transaction was active when
** the persistent error occurred, then the rollback journal may need
** to be replayed to restore the contents of the database file (as if
** it were a hot-journal).
*/
static int pager_error(Pager *pPager, int rc){
  int rc2 = rc & 0xff;
  assert( rc==SQLITE_OK || !MEMDB );
  assert(
       pPager->errCode==SQLITE_FULL ||
       pPager->errCode==SQLITE_OK ||
       (pPager->errCode & 0xff)==SQLITE_IOERR
  );
  if( rc2==SQLITE_FULL || rc2==SQLITE_IOERR ){
    pPager->errCode = rc;
  }
  return rc;
}

/*
** Execute a rollback if a transaction is active and unlock the
** database file.
**
** If the pager has already entered the error state, do not attempt
** the rollback at this time. Instead, pager_unlock() is called. The
** call to pager_unlock() will discard all in-memory pages, unlock
** the database file and clear the error state. If this means that
** there is a hot-journal left in the file-system, the next connection
** to obtain a shared lock on the pager (which may be this one) will
** roll it back.
**
** If the pager has not already entered the error state, but an IO or
** malloc error occurs during a rollback, then this will itself cause
** the pager to enter the error state. Which will be cleared by the
** call to pager_unlock(), as described above.
*/
static void pagerUnlockAndRollback(Pager *pPager){
  if( pPager->errCode==SQLITE_OK && pPager->state>=PAGER_RESERVED ){
    sqlite3BeginBenignMalloc();
    sqlite3PagerRollback(pPager);
    sqlite3EndBenignMalloc();
  }
  pager_unlock(pPager);
}

/*
** This routine ends a transaction. A transaction is usually ended by
** either a COMMIT or a ROLLBACK operation. This routine may be called
** after rollback of a hot-journal, or if an error occurs while opening
** the journal file or writing the very first journal-header of a
** database transaction.
**
** If the pager is in PAGER_SHARED or PAGER_UNLOCK state when this
** routine is called, it is a no-op (returns SQLITE_OK).
**
** Otherwise, any active savepoints are released.
**
** If the journal file is open, then it is "finalized". Once a journal
** file has been finalized it is not possible to use it to roll back a
** transaction. Nor will it be considered to be a hot-journal by this
** or any other database connection. Exactly how a journal is finalized
** depends on whether or not the pager is running in exclusive mode and
** the current journal-mode (Pager.journalMode value), as follows:
**
**   journalMode==MEMORY
**     Journal file descriptor is simply closed. This destroys an
**     in-memory journal.
**
**   journalMode==TRUNCATE
**     Journal file is truncated to zero bytes in size.
**
**   journalMode==PERSIST
**     The first 28 bytes of the journal file are zeroed. This invalidates
**     the first journal header in the file, and hence the entire journal
**     file. An invalid journal file cannot be rolled back.
**
**   journalMode==DELETE
**     The journal file is closed and deleted using sqlite3OsDelete().
**
**     If the pager is running in exclusive mode, this method of finalizing
**     the journal file is never used. Instead, if the journalMode is
**     DELETE and the pager is in exclusive mode, the method described under
**     journalMode==PERSIST is used instead.
**
** After the journal is finalized, if running in non-exclusive mode, the
** pager moves to PAGER_SHARED state (and downgrades the lock on the
** database file accordingly).
**
** If the pager is running in exclusive mode and is in PAGER_SYNCED state,
** it moves to PAGER_EXCLUSIVE. No locks are downgraded when running in
** exclusive mode.
**
** SQLITE_OK is returned if no error occurs. If an error occurs during
** any of the IO operations to finalize the journal file or unlock the
** database then the IO error code is returned to the user. If the
** operation to finalize the journal file fails, then the code still
** tries to unlock the database file if not in exclusive mode. If the
** unlock operation fails as well, then the first error code related
** to the first error encountered (the journal finalization one) is
** returned.
*/
static int pager_end_transaction(Pager *pPager, int hasMaster){
  int rc = SQLITE_OK;      /* Error code from journal finalization operation */
  int rc2 = SQLITE_OK;     /* Error code from db file unlock operation */

  if( pPager->state<PAGER_RESERVED ){
    return SQLITE_OK;
  }
  releaseAllSavepoints(pPager);

  assert( isOpen(pPager->jfd) || pPager->pInJournal==0 );
  if( isOpen(pPager->jfd) ){

    /* Finalize the journal file. */
    if( sqlite3IsMemJournal(pPager->jfd) ){
      assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY );
      sqlite3OsClose(pPager->jfd);
    }else if( pPager->journalMode==PAGER_JOURNALMODE_TRUNCATE ){
      if( pPager->journalOff==0 ){
        rc = SQLITE_OK;
      }else{
        rc = sqlite3OsTruncate(pPager->jfd, 0);
      }
      pPager->journalOff = 0;
      pPager->journalStarted = 0;
    }else if( pPager->exclusiveMode
     || pPager->journalMode==PAGER_JOURNALMODE_PERSIST
    ){
      rc = zeroJournalHdr(pPager, hasMaster);
      pager_error(pPager, rc);
      pPager->journalOff = 0;
      pPager->journalStarted = 0;
    }else{
      /* This branch may be executed with Pager.journalMode==MEMORY if
      ** a hot-journal was just rolled back. In this case the journal
      ** file should be closed and deleted. If this connection writes to
      ** the database file, it will do so using an in-memory journal.  */
      assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE
           || pPager->journalMode==PAGER_JOURNALMODE_MEMORY
      );
      sqlite3OsClose(pPager->jfd);
      if( !pPager->tempFile ){
        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
      }
    }

#ifdef SQLITE_CHECK_PAGES
    sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
#endif

    sqlite3PcacheCleanAll(pPager->pPCache);
    sqlite3BitvecDestroy(pPager->pInJournal);
    pPager->pInJournal = 0;
    pPager->nRec = 0;
  }

  if( !pPager->exclusiveMode ){
    rc2 = osUnlock(pPager->fd, SHARED_LOCK);
    pPager->state = PAGER_SHARED;
    pPager->changeCountDone = 0;
  }else if( pPager->state==PAGER_SYNCED ){
    pPager->state = PAGER_EXCLUSIVE;
  }
  pPager->setMaster = 0;
  pPager->needSync = 0;
  pPager->dbModified = 0;

  /* TODO: Is this optimal? Why is the db size invalidated here
  ** when the database file is not unlocked? */
  pPager->dbOrigSize = 0;
  sqlite3PcacheTruncate(pPager->pPCache, pPager->dbSize);
  if( !MEMDB ){
    pPager->dbSizeValid = 0;
  }

  return (rc==SQLITE_OK?rc2:rc);
}

/*
** Parameter aData must point to a buffer of pPager->pageSize bytes
** of data. Compute and return a checksum based ont the contents of the
** page of data and the current value of pPager->cksumInit.
**
** This is not a real checksum. It is really just the sum of the
** random initial value (pPager->cksumInit) and every 200th byte
** of the page data, starting with byte offset (pPager->pageSize%200).
** Each byte is interpreted as an 8-bit unsigned integer.
**
** Changing the formula used to compute this checksum results in an
** incompatible journal file format.
**
** If journal corruption occurs due to a power failure, the most likely
** scenario is that one end or the other of the record will be changed.
** It is much less likely that the two ends of the journal record will be
** correct and the middle be corrupt.  Thus, this "checksum" scheme,
** though fast and simple, catches the mostly likely kind of corruption.
*/
static u32 pager_cksum(Pager *pPager, const u8 *aData){
  u32 cksum = pPager->cksumInit;         /* Checksum value to return */
  int i = pPager->pageSize-200;          /* Loop counter */
  while( i>0 ){
    cksum += aData[i];
    i -= 200;
  }
  return cksum;
}

/*
** Read a single page from either the journal file (if isMainJrnl==1) or
** from the sub-journal (if isMainJrnl==0) and playback that page.
** The page begins at offset *pOffset into the file. The *pOffset
** value is increased to the start of the next page in the journal.
**
** The isMainJrnl flag is true if this is the main rollback journal and
** false for the statement journal.  The main rollback journal uses
** checksums - the statement journal does not.
**
** If the page number of the page record read from the (sub-)journal file
** is greater than the current value of Pager.dbSize, then playback is
** skipped and SQLITE_OK is returned.
**
** If pDone is not NULL, then it is a record of pages that have already
** been played back.  If the page at *pOffset has already been played back
** (if the corresponding pDone bit is set) then skip the playback.
** Make sure the pDone bit corresponding to the *pOffset page is set
** prior to returning.
**
** If the page record is successfully read from the (sub-)journal file
** and played back, then SQLITE_OK is returned. If an IO error occurs
** while reading the record from the (sub-)journal file or while writing
** to the database file, then the IO error code is returned. If data
** is successfully read from the (sub-)journal file but appears to be
** corrupted, SQLITE_DONE is returned. Data is considered corrupted in
** two circumstances:
**
**   * If the record page-number is illegal (0 or PAGER_MJ_PGNO), or
**   * If the record is being rolled back from the main journal file
**     and the checksum field does not match the record content.
**
** Neither of these two scenarios are possible during a savepoint rollback.
**
** If this is a savepoint rollback, then memory may have to be dynamically
** allocated by this function. If this is the case and an allocation fails,
** SQLITE_NOMEM is returned.
*/
static int pager_playback_one_page(
  Pager *pPager,                /* The pager being played back */
  int isMainJrnl,               /* 1 -> main journal. 0 -> sub-journal. */
  int isUnsync,                 /* True if reading from unsynced main journal */
  i64 *pOffset,                 /* Offset of record to playback */
  int isSavepnt,                /* True for a savepoint rollback */
  Bitvec *pDone                 /* Bitvec of pages already played back */
){
  int rc;
  PgHdr *pPg;                   /* An existing page in the cache */
  Pgno pgno;                    /* The page number of a page in journal */
  u32 cksum;                    /* Checksum used for sanity checking */
  char *aData;                  /* Temporary storage for the page */
  sqlite3_file *jfd;            /* The file descriptor for the journal file */

  assert( (isMainJrnl&~1)==0 );      /* isMainJrnl is 0 or 1 */
  assert( (isSavepnt&~1)==0 );       /* isSavepnt is 0 or 1 */
  assert( isMainJrnl || pDone );     /* pDone always used on sub-journals */
  assert( isSavepnt || pDone==0 );   /* pDone never used on non-savepoint */

  aData = pPager->pTmpSpace;
  assert( aData );         /* Temp storage must have already been allocated */

  /* Read the page number and page data from the journal or sub-journal
  ** file. Return an error code to the caller if an IO error occurs.
  */
  jfd = isMainJrnl ? pPager->jfd : pPager->sjfd;
  rc = read32bits(jfd, *pOffset, &pgno);
  if( rc!=SQLITE_OK ) return rc;
  rc = sqlite3OsRead(jfd, (u8*)aData, pPager->pageSize, (*pOffset)+4);
  if( rc!=SQLITE_OK ) return rc;
  *pOffset += pPager->pageSize + 4 + isMainJrnl*4;

  /* Sanity checking on the page.  This is more important that I originally
  ** thought.  If a power failure occurs while the journal is being written,
  ** it could cause invalid data to be written into the journal.  We need to
  ** detect this invalid data (with high probability) and ignore it.
  */
  if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
    assert( !isSavepnt );
    return SQLITE_DONE;
  }
  if( pgno>(Pgno)pPager->dbSize || sqlite3BitvecTest(pDone, pgno) ){
    return SQLITE_OK;
  }
  if( isMainJrnl ){
    rc = read32bits(jfd, (*pOffset)-4, &cksum);
    if( rc ) return rc;
    if( !isSavepnt && pager_cksum(pPager, (u8*)aData)!=cksum ){
      return SQLITE_DONE;
    }
  }

  if( pDone && (rc = sqlite3BitvecSet(pDone, pgno))!=SQLITE_OK ){
    return rc;
  }

  assert( pPager->state==PAGER_RESERVED || pPager->state>=PAGER_EXCLUSIVE );

  /* If the pager is in RESERVED state, then there must be a copy of this
  ** page in the pager cache. In this case just update the pager cache,
  ** not the database file. The page is left marked dirty in this case.
  **
  ** An exception to the above rule: If the database is in no-sync mode
  ** and a page is moved during an incremental vacuum then the page may
  ** not be in the pager cache. Later: if a malloc() or IO error occurs
  ** during a Movepage() call, then the page may not be in the cache
  ** either. So the condition described in the above paragraph is not
  ** assert()able.
  **
  ** If in EXCLUSIVE state, then we update the pager cache if it exists
  ** and the main file. The page is then marked not dirty.
  **
  ** Ticket #1171:  The statement journal might contain page content that is
  ** different from the page content at the start of the transaction.
  ** This occurs when a page is changed prior to the start of a statement
  ** then changed again within the statement.  When rolling back such a
  ** statement we must not write to the original database unless we know
  ** for certain that original page contents are synced into the main rollback
  ** journal.  Otherwise, a power loss might leave modified data in the
  ** database file without an entry in the rollback journal that can
  ** restore the database to its original form.  Two conditions must be
  ** met before writing to the database files. (1) the database must be
  ** locked.  (2) we know that the original page content is fully synced
  ** in the main journal either because the page is not in cache or else
  ** the page is marked as needSync==0.
  **
  ** 2008-04-14:  When attempting to vacuum a corrupt database file, it
  ** is possible to fail a statement on a database that does not yet exist.
  ** Do not attempt to write if database file has never been opened.
  */
  pPg = pager_lookup(pPager, pgno);
  assert( pPg || !MEMDB );
  PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
           PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, (u8*)aData),
           (isMainJrnl?"main-journal":"sub-journal")
  ));
  if( (pPager->state>=PAGER_EXCLUSIVE)
   && (pPg==0 || 0==(pPg->flags&PGHDR_NEED_SYNC))
   && isOpen(pPager->fd)
   && !isUnsync
  ){
    i64 ofst = (pgno-1)*(i64)pPager->pageSize;
    rc = sqlite3OsWrite(pPager->fd, (u8*)aData, pPager->pageSize, ofst);
    if( pgno>pPager->dbFileSize ){
      pPager->dbFileSize = pgno;
    }
    if( pPager->pBackup ){
      CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM);
      sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
      CODEC2(pPager, aData, pgno, 7, rc=SQLITE_NOMEM, aData);
    }
  }else if( !isMainJrnl && pPg==0 ){
    /* If this is a rollback of a savepoint and data was not written to
    ** the database and the page is not in-memory, there is a potential
    ** problem. When the page is next fetched by the b-tree layer, it
    ** will be read from the database file, which may or may not be
    ** current.
    **
    ** There are a couple of different ways this can happen. All are quite
    ** obscure. When running in synchronous mode, this can only happen
    ** if the page is on the free-list at the start of the transaction, then
    ** populated, then moved using sqlite3PagerMovepage().
    **
    ** The solution is to add an in-memory page to the cache containing
    ** the data just read from the sub-journal. Mark the page as dirty
    ** and if the pager requires a journal-sync, then mark the page as
    ** requiring a journal-sync before it is written.
    */
    assert( isSavepnt );
    if( (rc = sqlite3PagerAcquire(pPager, pgno, &pPg, 1))!=SQLITE_OK ){
      return rc;
    }
    pPg->flags &= ~PGHDR_NEED_READ;
    sqlite3PcacheMakeDirty(pPg);
  }
  if( pPg ){
    /* No page should ever be explicitly rolled back that is in use, except
    ** for page 1 which is held in use in order to keep the lock on the
    ** database active. However such a page may be rolled back as a result
    ** of an internal error resulting in an automatic call to
    ** sqlite3PagerRollback().
    */
    void *pData;
    pData = pPg->pData;
    memcpy(pData, (u8*)aData, pPager->pageSize);
    pPager->xReiniter(pPg);
    if( isMainJrnl && (!isSavepnt || *pOffset<=pPager->journalHdr) ){
      /* If the contents of this page were just restored from the main
      ** journal file, then its content must be as they were when the
      ** transaction was first opened. In this case we can mark the page
      ** as clean, since there will be no need to write it out to the.
      **
      ** There is one exception to this rule. If the page is being rolled
      ** back as part of a savepoint (or statement) rollback from an
      ** unsynced portion of the main journal file, then it is not safe
      ** to mark the page as clean. This is because marking the page as
      ** clean will clear the PGHDR_NEED_SYNC flag. Since the page is
      ** already in the journal file (recorded in Pager.pInJournal) and
      ** the PGHDR_NEED_SYNC flag is cleared, if the page is written to
      ** again within this transaction, it will be marked as dirty but
      ** the PGHDR_NEED_SYNC flag will not be set. It could then potentially
      ** be written out into the database file before its journal file
      ** segment is synced. If a crash occurs during or following this,
      ** database corruption may ensue.
      */
      sqlite3PcacheMakeClean(pPg);
    }
#ifdef SQLITE_CHECK_PAGES
    pPg->pageHash = pager_pagehash(pPg);
#endif
    /* If this was page 1, then restore the value of Pager.dbFileVers.
    ** Do this before any decoding. */
    if( pgno==1 ){
      memcpy(&pPager->dbFileVers, &((u8*)pData)[24],sizeof(pPager->dbFileVers));
    }

    /* Decode the page just read from disk */
    CODEC1(pPager, pData, pPg->pgno, 3, rc=SQLITE_NOMEM);
    sqlite3PcacheRelease(pPg);
  }
  return rc;
}

/*
** Parameter zMaster is the name of a master journal file. A single journal
** file that referred to the master journal file has just been rolled back.
** This routine checks if it is possible to delete the master journal file,
** and does so if it is.
**
** Argument zMaster may point to Pager.pTmpSpace. So that buffer is not
** available for use within this function.
**
** When a master journal file is created, it is populated with the names
** of all of its child journals, one after another, formatted as utf-8
** encoded text. The end of each child journal file is marked with a
** nul-terminator byte (0x00). i.e. the entire contents of a master journal
** file for a transaction involving two databases might be:
**
**   "/home/bill/a.db-journal\x00/home/bill/b.db-journal\x00"
**
** A master journal file may only be deleted once all of its child
** journals have been rolled back.
**
** This function reads the contents of the master-journal file into
** memory and loops through each of the child journal names. For
** each child journal, it checks if:
**
**   * if the child journal exists, and if so
**   * if the child journal contains a reference to master journal
**     file zMaster
**
** If a child journal can be found that matches both of the criteria
** above, this function returns without doing anything. Otherwise, if
** no such child journal can be found, file zMaster is deleted from
** the file-system using sqlite3OsDelete().
**
** If an IO error within this function, an error code is returned. This
** function allocates memory by calling sqlite3Malloc(). If an allocation
** fails, SQLITE_NOMEM is returned. Otherwise, if no IO or malloc errors
** occur, SQLITE_OK is returned.
**
** TODO: This function allocates a single block of memory to load
** the entire contents of the master journal file. This could be
** a couple of kilobytes or so - potentially larger than the page
** size.
*/
static int pager_delmaster(Pager *pPager, const char *zMaster){
  sqlite3_vfs *pVfs = pPager->pVfs;
  int rc;                   /* Return code */
  sqlite3_file *pMaster;    /* Malloc'd master-journal file descriptor */
  sqlite3_file *pJournal;   /* Malloc'd child-journal file descriptor */
  char *zMasterJournal = 0; /* Contents of master journal file */
  i64 nMasterJournal;       /* Size of master journal file */

  /* Allocate space for both the pJournal and pMaster file descriptors.
  ** If successful, open the master journal file for reading.
  */
  pMaster = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile * 2);
  pJournal = (sqlite3_file *)(((u8 *)pMaster) + pVfs->szOsFile);
  if( !pMaster ){
    rc = SQLITE_NOMEM;
  }else{
    const int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MASTER_JOURNAL);
    rc = sqlite3OsOpen(pVfs, zMaster, pMaster, flags, 0);
  }
  if( rc!=SQLITE_OK ) goto delmaster_out;

  rc = sqlite3OsFileSize(pMaster, &nMasterJournal);
  if( rc!=SQLITE_OK ) goto delmaster_out;

  if( nMasterJournal>0 ){
    char *zJournal;
    char *zMasterPtr = 0;
    int nMasterPtr = pVfs->mxPathname+1;

    /* Load the entire master journal file into space obtained from
    ** sqlite3_malloc() and pointed to by zMasterJournal.
    */
    zMasterJournal = sqlite3Malloc((int)nMasterJournal + nMasterPtr + 1);
    if( !zMasterJournal ){
      rc = SQLITE_NOMEM;
      goto delmaster_out;
    }
    zMasterPtr = &zMasterJournal[nMasterJournal+1];
    rc = sqlite3OsRead(pMaster, zMasterJournal, (int)nMasterJournal, 0);
    if( rc!=SQLITE_OK ) goto delmaster_out;
    zMasterJournal[nMasterJournal] = 0;

    zJournal = zMasterJournal;
    while( (zJournal-zMasterJournal)<nMasterJournal ){
      int exists;
      rc = sqlite3OsAccess(pVfs, zJournal, SQLITE_ACCESS_EXISTS, &exists);
      if( rc!=SQLITE_OK ){
        goto delmaster_out;
      }
      if( exists ){
        /* One of the journals pointed to by the master journal exists.
        ** Open it and check if it points at the master journal. If
        ** so, return without deleting the master journal file.
        */
        int c;
        int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL);
        rc = sqlite3OsOpen(pVfs, zJournal, pJournal, flags, 0);
        if( rc!=SQLITE_OK ){
          goto delmaster_out;
        }

        rc = readMasterJournal(pJournal, zMasterPtr, nMasterPtr);
        sqlite3OsClose(pJournal);
        if( rc!=SQLITE_OK ){
          goto delmaster_out;
        }

        c = zMasterPtr[0]!=0 && strcmp(zMasterPtr, zMaster)==0;
        if( c ){
          /* We have a match. Do not delete the master journal file. */
          goto delmaster_out;
        }
      }
      zJournal += (sqlite3Strlen30(zJournal)+1);
    }
  }

  rc = sqlite3OsDelete(pVfs, zMaster, 0);

delmaster_out:
  if( zMasterJournal ){
    sqlite3_free(zMasterJournal);
  }
  if( pMaster ){
    sqlite3OsClose(pMaster);
    assert( !isOpen(pJournal) );
  }
  sqlite3_free(pMaster);
  return rc;
}


/*
** This function is used to change the actual size of the database
** file in the file-system. This only happens when committing a transaction,
** or rolling back a transaction (including rolling back a hot-journal).
**
** If the main database file is not open, or an exclusive lock is not
** held, this function is a no-op. Otherwise, the size of the file is
** changed to nPage pages (nPage*pPager->pageSize bytes). If the file
** on disk is currently larger than nPage pages, then use the VFS
** xTruncate() method to truncate it.
**
** Or, it might might be the case that the file on disk is smaller than
** nPage pages. Some operating system implementations can get confused if
** you try to truncate a file to some size that is larger than it
** currently is, so detect this case and write a single zero byte to
** the end of the new file instead.
**
** If successful, return SQLITE_OK. If an IO error occurs while modifying
** the database file, return the error code to the caller.
*/
static int pager_truncate(Pager *pPager, Pgno nPage){
  int rc = SQLITE_OK;
  if( pPager->state>=PAGER_EXCLUSIVE && isOpen(pPager->fd) ){
    i64 currentSize, newSize;
    /* TODO: Is it safe to use Pager.dbFileSize here? */
    rc = sqlite3OsFileSize(pPager->fd, &currentSize);
    newSize = pPager->pageSize*(i64)nPage;
    if( rc==SQLITE_OK && currentSize!=newSize ){
      if( currentSize>newSize ){
        rc = sqlite3OsTruncate(pPager->fd, newSize);
      }else{
        rc = sqlite3OsWrite(pPager->fd, "", 1, newSize-1);
      }
      if( rc==SQLITE_OK ){
        pPager->dbFileSize = nPage;
      }
    }
  }
  return rc;
}

/*
** Set the value of the Pager.sectorSize variable for the given
** pager based on the value returned by the xSectorSize method
** of the open database file. The sector size will be used used
** to determine the size and alignment of journal header and
** master journal pointers within created journal files.
**
** For temporary files the effective sector size is always 512 bytes.
**
** Otherwise, for non-temporary files, the effective sector size is
** the value returned by the xSectorSize() method rounded up to 32 if
** it is less than 32, or rounded down to MAX_SECTOR_SIZE if it
** is greater than MAX_SECTOR_SIZE.
*/
static void setSectorSize(Pager *pPager){
  assert( isOpen(pPager->fd) || pPager->tempFile );

  if( !pPager->tempFile ){
    /* Sector size doesn't matter for temporary files. Also, the file
    ** may not have been opened yet, in which case the OsSectorSize()
    ** call will segfault.
    */
    pPager->sectorSize = sqlite3OsSectorSize(pPager->fd);
  }
  if( pPager->sectorSize<32 ){
    pPager->sectorSize = 512;
  }
  if( pPager->sectorSize>MAX_SECTOR_SIZE ){
    assert( MAX_SECTOR_SIZE>=512 );
    pPager->sectorSize = MAX_SECTOR_SIZE;
  }
}

/*
** Playback the journal and thus restore the database file to
** the state it was in before we started making changes.
**
** The journal file format is as follows:
**
**  (1)  8 byte prefix.  A copy of aJournalMagic[].
**  (2)  4 byte big-endian integer which is the number of valid page records
**       in the journal.  If this value is 0xffffffff, then compute the
**       number of page records from the journal size.
**  (3)  4 byte big-endian integer which is the initial value for the
**       sanity checksum.
**  (4)  4 byte integer which is the number of pages to truncate the
**       database to during a rollback.
**  (5)  4 byte big-endian integer which is the sector size.  The header
**       is this many bytes in size.
**  (6)  4 byte big-endian integer which is the page size.
**  (7)  zero padding out to the next sector size.
**  (8)  Zero or more pages instances, each as follows:
**        +  4 byte page number.
**        +  pPager->pageSize bytes of data.
**        +  4 byte checksum
**
** When we speak of the journal header, we mean the first 7 items above.
** Each entry in the journal is an instance of the 8th item.
**
** Call the value from the second bullet "nRec".  nRec is the number of
** valid page entries in the journal.  In most cases, you can compute the
** value of nRec from the size of the journal file.  But if a power
** failure occurred while the journal was being written, it could be the
** case that the size of the journal file had already been increased but
** the extra entries had not yet made it safely to disk.  In such a case,
** the value of nRec computed from the file size would be too large.  For
** that reason, we always use the nRec value in the header.
**
** If the nRec value is 0xffffffff it means that nRec should be computed
** from the file size.  This value is used when the user selects the
** no-sync option for the journal.  A power failure could lead to corruption
** in this case.  But for things like temporary table (which will be
** deleted when the power is restored) we don't care.
**
** If the file opened as the journal file is not a well-formed
** journal file then all pages up to the first corrupted page are rolled
** back (or no pages if the journal header is corrupted). The journal file
** is then deleted and SQLITE_OK returned, just as if no corruption had
** been encountered.
**
** If an I/O or malloc() error occurs, the journal-file is not deleted
** and an error code is returned.
**
** The isHot parameter indicates that we are trying to rollback a journal
** that might be a hot journal.  Or, it could be that the journal is
** preserved because of JOURNALMODE_PERSIST or JOURNALMODE_TRUNCATE.
** If the journal really is hot, reset the pager cache prior rolling
** back any content.  If the journal is merely persistent, no reset is
** needed.
*/
static int pager_playback(Pager *pPager, int isHot){
  sqlite3_vfs *pVfs = pPager->pVfs;
  i64 szJ;                 /* Size of the journal file in bytes */
  u32 nRec;                /* Number of Records in the journal */
  u32 u;                   /* Unsigned loop counter */
  Pgno mxPg = 0;           /* Size of the original file in pages */
  int rc;                  /* Result code of a subroutine */
  int res = 1;             /* Value returned by sqlite3OsAccess() */
  char *zMaster = 0;       /* Name of master journal file if any */
  int needPagerReset;      /* True to reset page prior to first page rollback */

  /* Figure out how many records are in the journal.  Abort early if
  ** the journal is empty.
  */
  assert( isOpen(pPager->jfd) );
  rc = sqlite3OsFileSize(pPager->jfd, &szJ);
  if( rc!=SQLITE_OK || szJ==0 ){
    goto end_playback;
  }

  /* Read the master journal name from the journal, if it is present.
  ** If a master journal file name is specified, but the file is not
  ** present on disk, then the journal is not hot and does not need to be
  ** played back.
  **
  ** TODO: Technically the following is an error because it assumes that
  ** buffer Pager.pTmpSpace is (mxPathname+1) bytes or larger. i.e. that
  ** (pPager->pageSize >= pPager->pVfs->mxPathname+1). Using os_unix.c,
  **  mxPathname is 512, which is the same as the minimum allowable value
  ** for pageSize.
  */
  zMaster = pPager->pTmpSpace;
  rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
  if( rc==SQLITE_OK && zMaster[0] ){
    rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
  }
  zMaster = 0;
  if( rc!=SQLITE_OK || !res ){
    goto end_playback;
  }
  pPager->journalOff = 0;
  needPagerReset = isHot;

  /* This loop terminates either when a readJournalHdr() or
  ** pager_playback_one_page() call returns SQLITE_DONE or an IO error
  ** occurs.
  */
  while( 1 ){
    int isUnsync = 0;

    /* Read the next journal header from the journal file.  If there are
    ** not enough bytes left in the journal file for a complete header, or
    ** it is corrupted, then a process must of failed while writing it.
    ** This indicates nothing more needs to be rolled back.
    */
    rc = readJournalHdr(pPager, isHot, szJ, &nRec, &mxPg);
    if( rc!=SQLITE_OK ){
      if( rc==SQLITE_DONE ){
        rc = SQLITE_OK;
      }
      goto end_playback;
    }

    /* If nRec is 0xffffffff, then this journal was created by a process
    ** working in no-sync mode. This means that the rest of the journal
    ** file consists of pages, there are no more journal headers. Compute
    ** the value of nRec based on this assumption.
    */
    if( nRec==0xffffffff ){
      assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) );
      nRec = (int)((szJ - JOURNAL_HDR_SZ(pPager))/JOURNAL_PG_SZ(pPager));
    }

    /* If nRec is 0 and this rollback is of a transaction created by this
    ** process and if this is the final header in the journal, then it means
    ** that this part of the journal was being filled but has not yet been
    ** synced to disk.  Compute the number of pages based on the remaining
    ** size of the file.
    **
    ** The third term of the test was added to fix ticket #2565.
    ** When rolling back a hot journal, nRec==0 always means that the next
    ** chunk of the journal contains zero pages to be rolled back.  But
    ** when doing a ROLLBACK and the nRec==0 chunk is the last chunk in
    ** the journal, it means that the journal might contain additional
    ** pages that need to be rolled back and that the number of pages
    ** should be computed based on the journal file size.
    */
    if( nRec==0 && !isHot &&
        pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){
      nRec = (int)((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager));
      isUnsync = 1;
    }

    /* If this is the first header read from the journal, truncate the
    ** database file back to its original size.
    */
    if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
      rc = pager_truncate(pPager, mxPg);
      if( rc!=SQLITE_OK ){
        goto end_playback;
      }
      pPager->dbSize = mxPg;
    }

    /* Copy original pages out of the journal and back into the
    ** database file and/or page cache.
    */
    for(u=0; u<nRec; u++){
      if( needPagerReset ){
        pager_reset(pPager);
        needPagerReset = 0;
      }
      rc = pager_playback_one_page(pPager,1,isUnsync,&pPager->journalOff,0,0);
      if( rc!=SQLITE_OK ){
        if( rc==SQLITE_DONE ){
          rc = SQLITE_OK;
          pPager->journalOff = szJ;
          break;
        }else{
          /* If we are unable to rollback, quit and return the error
          ** code.  This will cause the pager to enter the error state
          ** so that no further harm will be done.  Perhaps the next
          ** process to come along will be able to rollback the database.
          */
          goto end_playback;
        }
      }
    }
  }
  /*NOTREACHED*/
  assert( 0 );

end_playback:
  /* Following a rollback, the database file should be back in its original
  ** state prior to the start of the transaction, so invoke the
  ** SQLITE_FCNTL_DB_UNCHANGED file-control method to disable the
  ** assertion that the transaction counter was modified.
  */
  assert(
    pPager->fd->pMethods==0 ||
    sqlite3OsFileControl(pPager->fd,SQLITE_FCNTL_DB_UNCHANGED,0)>=SQLITE_OK
  );

  /* If this playback is happening automatically as a result of an IO or
  ** malloc error that occurred after the change-counter was updated but
  ** before the transaction was committed, then the change-counter
  ** modification may just have been reverted. If this happens in exclusive
  ** mode, then subsequent transactions performed by the connection will not
  ** update the change-counter at all. This may lead to cache inconsistency
  ** problems for other processes at some point in the future. So, just
  ** in case this has happened, clear the changeCountDone flag now.
  */
  pPager->changeCountDone = pPager->tempFile;

  if( rc==SQLITE_OK ){
    zMaster = pPager->pTmpSpace;
    rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
    testcase( rc!=SQLITE_OK );
  }
  if( rc==SQLITE_OK && pPager->noSync==0 && pPager->state>=PAGER_EXCLUSIVE ){
    rc = sqlite3OsSync(pPager->fd, pPager->sync_flags);
  }
  if( rc==SQLITE_OK ){
    rc = pager_end_transaction(pPager, zMaster[0]!='\0');
    testcase( rc!=SQLITE_OK );
  }
  if( rc==SQLITE_OK && zMaster[0] && res ){
    /* If there was a master journal and this routine will return success,
    ** see if it is possible to delete the master journal.
    */
    rc = pager_delmaster(pPager, zMaster);
    testcase( rc!=SQLITE_OK );
  }

  /* The Pager.sectorSize variable may have been updated while rolling
  ** back a journal created by a process with a different sector size
  ** value. Reset it to the correct value for this process.
  */
  setSectorSize(pPager);
  return rc;
}

/*
** Playback savepoint pSavepoint. Or, if pSavepoint==NULL, then playback
** the entire master journal file. The case pSavepoint==NULL occurs when
** a ROLLBACK TO command is invoked on a SAVEPOINT that is a transaction
** savepoint.
**
** When pSavepoint is not NULL (meaning a non-transaction savepoint is
** being rolled back), then the rollback consists of up to three stages,
** performed in the order specified:
**
**   * Pages are played back from the main journal starting at byte
**     offset PagerSavepoint.iOffset and continuing to
**     PagerSavepoint.iHdrOffset, or to the end of the main journal
**     file if PagerSavepoint.iHdrOffset is zero.
**
**   * If PagerSavepoint.iHdrOffset is not zero, then pages are played
**     back starting from the journal header immediately following
**     PagerSavepoint.iHdrOffset to the end of the main journal file.
**
**   * Pages are then played back from the sub-journal file, starting
**     with the PagerSavepoint.iSubRec and continuing to the end of
**     the journal file.
**
** Throughout the rollback process, each time a page is rolled back, the
** corresponding bit is set in a bitvec structure (variable pDone in the
** implementation below). This is used to ensure that a page is only
** rolled back the first time it is encountered in either journal.
**
** If pSavepoint is NULL, then pages are only played back from the main
** journal file. There is no need for a bitvec in this case.
**
** In either case, before playback commences the Pager.dbSize variable
** is reset to the value that it held at the start of the savepoint
** (or transaction). No page with a page-number greater than this value
** is played back. If one is encountered it is simply skipped.
*/
static int pagerPlaybackSavepoint(Pager *pPager, PagerSavepoint *pSavepoint){
  i64 szJ;                 /* Effective size of the main journal */
  i64 iHdrOff;             /* End of first segment of main-journal records */
  int rc = SQLITE_OK;      /* Return code */
  Bitvec *pDone = 0;       /* Bitvec to ensure pages played back only once */

  assert( pPager->state>=PAGER_SHARED );

  /* Allocate a bitvec to use to store the set of pages rolled back */
  if( pSavepoint ){
    pDone = sqlite3BitvecCreate(pSavepoint->nOrig);
    if( !pDone ){
      return SQLITE_NOMEM;
    }
  }

  /* Set the database size back to the value it was before the savepoint
  ** being reverted was opened.
  */
  pPager->dbSize = pSavepoint ? pSavepoint->nOrig : pPager->dbOrigSize;

  /* Use pPager->journalOff as the effective size of the main rollback
  ** journal.  The actual file might be larger than this in
  ** PAGER_JOURNALMODE_TRUNCATE or PAGER_JOURNALMODE_PERSIST.  But anything
  ** past pPager->journalOff is off-limits to us.
  */
  szJ = pPager->journalOff;

  /* Begin by rolling back records from the main journal starting at
  ** PagerSavepoint.iOffset and continuing to the next journal header.
  ** There might be records in the main journal that have a page number
  ** greater than the current database size (pPager->dbSize) but those
  ** will be skipped automatically.  Pages are added to pDone as they
  ** are played back.
  */
  if( pSavepoint ){
    iHdrOff = pSavepoint->iHdrOffset ? pSavepoint->iHdrOffset : szJ;
    pPager->journalOff = pSavepoint->iOffset;
    while( rc==SQLITE_OK && pPager->journalOff<iHdrOff ){
      rc = pager_playback_one_page(pPager, 1, 0, &pPager->journalOff, 1, pDone);
    }
    assert( rc!=SQLITE_DONE );
  }else{
    pPager->journalOff = 0;
  }

  /* Continue rolling back records out of the main journal starting at
  ** the first journal header seen and continuing until the effective end
  ** of the main journal file.  Continue to skip out-of-range pages and
  ** continue adding pages rolled back to pDone.
  */
  while( rc==SQLITE_OK && pPager->journalOff<szJ ){
    u32 ii;            /* Loop counter */
    u32 nJRec = 0;     /* Number of Journal Records */
    u32 dummy;
    rc = readJournalHdr(pPager, 0, szJ, &nJRec, &dummy);
    assert( rc!=SQLITE_DONE );

    /*
    ** The "pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff"
    ** test is related to ticket #2565.  See the discussion in the
    ** pager_playback() function for additional information.
    */
    if( nJRec==0
     && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff
    ){
      nJRec = (u32)((szJ - pPager->journalOff)/JOURNAL_PG_SZ(pPager));
    }
    for(ii=0; rc==SQLITE_OK && ii<nJRec && pPager->journalOff<szJ; ii++){
      rc = pager_playback_one_page(pPager, 1, 0, &pPager->journalOff, 1, pDone);
    }
    assert( rc!=SQLITE_DONE );
  }
  assert( rc!=SQLITE_OK || pPager->journalOff==szJ );

  /* Finally,  rollback pages from the sub-journal.  Page that were
  ** previously rolled back out of the main journal (and are hence in pDone)
  ** will be skipped.  Out-of-range pages are also skipped.
  */
  if( pSavepoint ){
    u32 ii;            /* Loop counter */
    i64 offset = pSavepoint->iSubRec*(4+pPager->pageSize);
    for(ii=pSavepoint->iSubRec; rc==SQLITE_OK && ii<pPager->nSubRec; ii++){
      assert( offset==ii*(4+pPager->pageSize) );
      rc = pager_playback_one_page(pPager, 0, 0, &offset, 1, pDone);
    }
    assert( rc!=SQLITE_DONE );
  }

  sqlite3BitvecDestroy(pDone);
  if( rc==SQLITE_OK ){
    pPager->journalOff = szJ;
  }
  return rc;
}

/*
** Change the maximum number of in-memory pages that are allowed.
*/
SQLITE_PRIVATE void sqlite3PagerSetCachesize(Pager *pPager, int mxPage){
  sqlite3PcacheSetCachesize(pPager->pPCache, mxPage);
}

/*
** Adjust the robustness of the database to damage due to OS crashes
** or power failures by changing the number of syncs()s when writing
** the rollback journal.  There are three levels:
**
**    OFF       sqlite3OsSync() is never called.  This is the default
**              for temporary and transient files.
**
**    NORMAL    The journal is synced once before writes begin on the
**              database.  This is normally adequate protection, but
**              it is theoretically possible, though very unlikely,
**              that an inopertune power failure could leave the journal
**              in a state which would cause damage to the database
**              when it is rolled back.
**
**    FULL      The journal is synced twice before writes begin on the
**              database (with some additional information - the nRec field
**              of the journal header - being written in between the two
**              syncs).  If we assume that writing a
**              single disk sector is atomic, then this mode provides
**              assurance that the journal will not be corrupted to the
**              point of causing damage to the database during rollback.
**
** Numeric values associated with these states are OFF==1, NORMAL=2,
** and FULL=3.
*/
#ifndef SQLITE_OMIT_PAGER_PRAGMAS
SQLITE_PRIVATE void sqlite3PagerSetSafetyLevel(Pager *pPager, int level, int bFullFsync){
  pPager->noSync =  (level==1 || pPager->tempFile) ?1:0;
  pPager->fullSync = (level==3 && !pPager->tempFile) ?1:0;
  pPager->sync_flags = (bFullFsync?SQLITE_SYNC_FULL:SQLITE_SYNC_NORMAL);
  if( pPager->noSync ) pPager->needSync = 0;
}
#endif

/*
** The following global variable is incremented whenever the library
** attempts to open a temporary file.  This information is used for
** testing and analysis only.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_opentemp_count = 0;
#endif

/*
** Open a temporary file.
**
** Write the file descriptor into *pFile. Return SQLITE_OK on success
** or some other error code if we fail. The OS will automatically
** delete the temporary file when it is closed.
**
** The flags passed to the VFS layer xOpen() call are those specified
** by parameter vfsFlags ORed with the following:
**
**     SQLITE_OPEN_READWRITE
**     SQLITE_OPEN_CREATE
**     SQLITE_OPEN_EXCLUSIVE
**     SQLITE_OPEN_DELETEONCLOSE
*/
static int pagerOpentemp(
  Pager *pPager,        /* The pager object */
  sqlite3_file *pFile,  /* Write the file descriptor here */
  int vfsFlags          /* Flags passed through to the VFS */
){
  int rc;               /* Return code */

#ifdef SQLITE_TEST
  sqlite3_opentemp_count++;  /* Used for testing and analysis only */
#endif

  vfsFlags |=  SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
            SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE;
  rc = sqlite3OsOpen(pPager->pVfs, 0, pFile, vfsFlags, 0);
  assert( rc!=SQLITE_OK || isOpen(pFile) );
  return rc;
}

/*
** Set the busy handler function.
**
** The pager invokes the busy-handler if sqlite3OsLock() returns
** SQLITE_BUSY when trying to upgrade from no-lock to a SHARED lock,
** or when trying to upgrade from a RESERVED lock to an EXCLUSIVE
** lock. It does *not* invoke the busy handler when upgrading from
** SHARED to RESERVED, or when upgrading from SHARED to EXCLUSIVE
** (which occurs during hot-journal rollback). Summary:
**
**   Transition                        | Invokes xBusyHandler
**   --------------------------------------------------------
**   NO_LOCK       -> SHARED_LOCK      | Yes
**   SHARED_LOCK   -> RESERVED_LOCK    | No
**   SHARED_LOCK   -> EXCLUSIVE_LOCK   | No
**   RESERVED_LOCK -> EXCLUSIVE_LOCK   | Yes
**
** If the busy-handler callback returns non-zero, the lock is
** retried. If it returns zero, then the SQLITE_BUSY error is
** returned to the caller of the pager API function.
*/
SQLITE_PRIVATE void sqlite3PagerSetBusyhandler(
  Pager *pPager,                       /* Pager object */
  int (*xBusyHandler)(void *),         /* Pointer to busy-handler function */
  void *pBusyHandlerArg                /* Argument to pass to xBusyHandler */
){
  pPager->xBusyHandler = xBusyHandler;
  pPager->pBusyHandlerArg = pBusyHandlerArg;
}

/*
** Report the current page size and number of reserved bytes back
** to the codec.
*/
#ifdef SQLITE_HAS_CODEC
static void pagerReportSize(Pager *pPager){
  if( pPager->xCodecSizeChng ){
    pPager->xCodecSizeChng(pPager->pCodec, pPager->pageSize,
                           (int)pPager->nReserve);
  }
}
#else
# define pagerReportSize(X)     /* No-op if we do not support a codec */
#endif

/*
** Change the page size used by the Pager object. The new page size
** is passed in *pPageSize.
**
** If the pager is in the error state when this function is called, it
** is a no-op. The value returned is the error state error code (i.e.
** one of SQLITE_IOERR, SQLITE_CORRUPT or SQLITE_FULL).
**
** Otherwise, if all of the following are true:
**
**   * the new page size (value of *pPageSize) is valid (a power
**     of two between 512 and SQLITE_MAX_PAGE_SIZE, inclusive), and
**
**   * there are no outstanding page references, and
**
**   * the database is either not an in-memory database or it is
**     an in-memory database that currently consists of zero pages.
**
** then the pager object page size is set to *pPageSize.
**
** If the page size is changed, then this function uses sqlite3PagerMalloc()
** to obtain a new Pager.pTmpSpace buffer. If this allocation attempt
** fails, SQLITE_NOMEM is returned and the page size remains unchanged.
** In all other cases, SQLITE_OK is returned.
**
** If the page size is not changed, either because one of the enumerated
** conditions above is not true, the pager was in error state when this
** function was called, or because the memory allocation attempt failed,
** then *pPageSize is set to the old, retained page size before returning.
*/
SQLITE_PRIVATE int sqlite3PagerSetPagesize(Pager *pPager, u16 *pPageSize, int nReserve){
  int rc = pPager->errCode;

  if( rc==SQLITE_OK ){
    u16 pageSize = *pPageSize;
    assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) );
    if( (pPager->memDb==0 || pPager->dbSize==0)
     && sqlite3PcacheRefCount(pPager->pPCache)==0
     && pageSize && pageSize!=pPager->pageSize
    ){
      char *pNew = (char *)sqlite3PageMalloc(pageSize);
      if( !pNew ){
        rc = SQLITE_NOMEM;
      }else{
        pager_reset(pPager);
        pPager->pageSize = pageSize;
        sqlite3PageFree(pPager->pTmpSpace);
        pPager->pTmpSpace = pNew;
        sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
      }
    }
    *pPageSize = (u16)pPager->pageSize;
    if( nReserve<0 ) nReserve = pPager->nReserve;
    assert( nReserve>=0 && nReserve<1000 );
    pPager->nReserve = (i16)nReserve;
    pagerReportSize(pPager);
  }
  return rc;
}

/*
** Return a pointer to the "temporary page" buffer held internally
** by the pager.  This is a buffer that is big enough to hold the
** entire content of a database page.  This buffer is used internally
** during rollback and will be overwritten whenever a rollback
** occurs.  But other modules are free to use it too, as long as
** no rollbacks are happening.
*/
SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager *pPager){
  return pPager->pTmpSpace;
}

/*
** Attempt to set the maximum database page count if mxPage is positive.
** Make no changes if mxPage is zero or negative.  And never reduce the
** maximum page count below the current size of the database.
**
** Regardless of mxPage, return the current maximum page count.
*/
SQLITE_PRIVATE int sqlite3PagerMaxPageCount(Pager *pPager, int mxPage){
  if( mxPage>0 ){
    pPager->mxPgno = mxPage;
  }
  sqlite3PagerPagecount(pPager, 0);
  return pPager->mxPgno;
}

/*
** The following set of routines are used to disable the simulated
** I/O error mechanism.  These routines are used to avoid simulated
** errors in places where we do not care about errors.
**
** Unless -DSQLITE_TEST=1 is used, these routines are all no-ops
** and generate no code.
*/
#ifdef SQLITE_TEST
SQLITE_API extern int sqlite3_io_error_pending;
SQLITE_API extern int sqlite3_io_error_hit;
static int saved_cnt;
void disable_simulated_io_errors(void){
  saved_cnt = sqlite3_io_error_pending;
  sqlite3_io_error_pending = -1;
}
void enable_simulated_io_errors(void){
  sqlite3_io_error_pending = saved_cnt;
}
#else
# define disable_simulated_io_errors()
# define enable_simulated_io_errors()
#endif

/*
** Read the first N bytes from the beginning of the file into memory
** that pDest points to.
**
** If the pager was opened on a transient file (zFilename==""), or
** opened on a file less than N bytes in size, the output buffer is
** zeroed and SQLITE_OK returned. The rationale for this is that this
** function is used to read database headers, and a new transient or
** zero sized database has a header than consists entirely of zeroes.
**
** If any IO error apart from SQLITE_IOERR_SHORT_READ is encountered,
** the error code is returned to the caller and the contents of the
** output buffer undefined.
*/
SQLITE_PRIVATE int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){
  int rc = SQLITE_OK;
  memset(pDest, 0, N);
  assert( isOpen(pPager->fd) || pPager->tempFile );
  if( isOpen(pPager->fd) ){
    IOTRACE(("DBHDR %p 0 %d\n", pPager, N))
    rc = sqlite3OsRead(pPager->fd, pDest, N, 0);
    if( rc==SQLITE_IOERR_SHORT_READ ){
      rc = SQLITE_OK;
    }
  }
  return rc;
}

/*
** Return the total number of pages in the database file associated
** with pPager. Normally, this is calculated as (<db file size>/<page-size>).
** However, if the file is between 1 and <page-size> bytes in size, then
** this is considered a 1 page file.
**
** If the pager is in error state when this function is called, then the
** error state error code is returned and *pnPage left unchanged. Or,
** if the file system has to be queried for the size of the file and
** the query attempt returns an IO error, the IO error code is returned
** and *pnPage is left unchanged.
**
** Otherwise, if everything is successful, then SQLITE_OK is returned
** and *pnPage is set to the number of pages in the database.
*/
SQLITE_PRIVATE int sqlite3PagerPagecount(Pager *pPager, int *pnPage){
  Pgno nPage;               /* Value to return via *pnPage */

  /* If the pager is already in the error state, return the error code. */
  if( pPager->errCode ){
    return pPager->errCode;
  }

  /* Determine the number of pages in the file. Store this in nPage. */
  if( pPager->dbSizeValid ){
    nPage = pPager->dbSize;
  }else{
    int rc;                 /* Error returned by OsFileSize() */
    i64 n = 0;              /* File size in bytes returned by OsFileSize() */

    assert( isOpen(pPager->fd) || pPager->tempFile );
    if( isOpen(pPager->fd) && (0 != (rc = sqlite3OsFileSize(pPager->fd, &n))) ){
      pager_error(pPager, rc);
      return rc;
    }
    if( n>0 && n<pPager->pageSize ){
      nPage = 1;
    }else{
      nPage = (Pgno)(n / pPager->pageSize);
    }
    if( pPager->state!=PAGER_UNLOCK ){
      pPager->dbSize = nPage;
      pPager->dbFileSize = nPage;
      pPager->dbSizeValid = 1;
    }
  }

  /* If the current number of pages in the file is greater than the
  ** configured maximum pager number, increase the allowed limit so
  ** that the file can be read.
  */
  if( nPage>pPager->mxPgno ){
    pPager->mxPgno = (Pgno)nPage;
  }

  /* Set the output variable and return SQLITE_OK */
  if( pnPage ){
    *pnPage = nPage;
  }
  return SQLITE_OK;
}


/*
** Try to obtain a lock of type locktype on the database file. If
** a similar or greater lock is already held, this function is a no-op
** (returning SQLITE_OK immediately).
**
** Otherwise, attempt to obtain the lock using sqlite3OsLock(). Invoke
** the busy callback if the lock is currently not available. Repeat
** until the busy callback returns false or until the attempt to
** obtain the lock succeeds.
**
** Return SQLITE_OK on success and an error code if we cannot obtain
** the lock. If the lock is obtained successfully, set the Pager.state
** variable to locktype before returning.
*/
static int pager_wait_on_lock(Pager *pPager, int locktype){
  int rc;                              /* Return code */

  /* The OS lock values must be the same as the Pager lock values */
  assert( PAGER_SHARED==SHARED_LOCK );
  assert( PAGER_RESERVED==RESERVED_LOCK );
  assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK );

  /* If the file is currently unlocked then the size must be unknown. It
  ** must not have been modified at this point.
  */
  assert( pPager->state>=PAGER_SHARED || pPager->dbSizeValid==0 );
  assert( pPager->state>=PAGER_SHARED || pPager->dbModified==0 );

  /* Check that this is either a no-op (because the requested lock is
  ** already held, or one of the transistions that the busy-handler
  ** may be invoked during, according to the comment above
  ** sqlite3PagerSetBusyhandler().
  */
  assert( (pPager->state>=locktype)
       || (pPager->state==PAGER_UNLOCK && locktype==PAGER_SHARED)
       || (pPager->state==PAGER_RESERVED && locktype==PAGER_EXCLUSIVE)
  );

  if( pPager->state>=locktype ){
    rc = SQLITE_OK;
  }else{
    do {
      rc = sqlite3OsLock(pPager->fd, locktype);
    }while( rc==SQLITE_BUSY && pPager->xBusyHandler(pPager->pBusyHandlerArg) );
    if( rc==SQLITE_OK ){
      pPager->state = (u8)locktype;
      IOTRACE(("LOCK %p %d\n", pPager, locktype))
    }
  }
  return rc;
}

/*
** Function assertTruncateConstraint(pPager) checks that one of the
** following is true for all dirty pages currently in the page-cache:
**
**   a) The page number is less than or equal to the size of the
**      current database image, in pages, OR
**
**   b) if the page content were written at this time, it would not
**      be necessary to write the current content out to the sub-journal
**      (as determined by function subjRequiresPage()).
**
** If the condition asserted by this function were not true, and the
** dirty page were to be discarded from the cache via the pagerStress()
** routine, pagerStress() would not write the current page content to
** the database file. If a savepoint transaction were rolled back after
** this happened, the correct behaviour would be to restore the current
** content of the page. However, since this content is not present in either
** the database file or the portion of the rollback journal and
** sub-journal rolled back the content could not be restored and the
** database image would become corrupt. It is therefore fortunate that
** this circumstance cannot arise.
*/
#if defined(SQLITE_DEBUG)
static void assertTruncateConstraintCb(PgHdr *pPg){
  assert( pPg->flags&PGHDR_DIRTY );
  assert( !subjRequiresPage(pPg) || pPg->pgno<=pPg->pPager->dbSize );
}
static void assertTruncateConstraint(Pager *pPager){
  sqlite3PcacheIterateDirty(pPager->pPCache, assertTruncateConstraintCb);
}
#else
# define assertTruncateConstraint(pPager)
#endif

/*
** Truncate the in-memory database file image to nPage pages. This
** function does not actually modify the database file on disk. It
** just sets the internal state of the pager object so that the
** truncation will be done when the current transaction is committed.
*/
SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager *pPager, Pgno nPage){
  assert( pPager->dbSizeValid );
  assert( pPager->dbSize>=nPage );
  assert( pPager->state>=PAGER_RESERVED );
  pPager->dbSize = nPage;
  assertTruncateConstraint(pPager);
}

/*
** Shutdown the page cache.  Free all memory and close all files.
**
** If a transaction was in progress when this routine is called, that
** transaction is rolled back.  All outstanding pages are invalidated
** and their memory is freed.  Any attempt to use a page associated
** with this page cache after this function returns will likely
** result in a coredump.
**
** This function always succeeds. If a transaction is active an attempt
** is made to roll it back. If an error occurs during the rollback
** a hot journal may be left in the filesystem but no error is returned
** to the caller.
*/
SQLITE_PRIVATE int sqlite3PagerClose(Pager *pPager){
  disable_simulated_io_errors();
  sqlite3BeginBenignMalloc();
  pPager->errCode = 0;
  pPager->exclusiveMode = 0;
  pager_reset(pPager);
  if( MEMDB ){
    pager_unlock(pPager);
  }else{
    /* Set Pager.journalHdr to -1 for the benefit of the pager_playback()
    ** call which may be made from within pagerUnlockAndRollback(). If it
    ** is not -1, then the unsynced portion of an open journal file may
    ** be played back into the database. If a power failure occurs while
    ** this is happening, the database may become corrupt.
    */
    pPager->journalHdr = -1;
    pagerUnlockAndRollback(pPager);
  }
  sqlite3EndBenignMalloc();
  enable_simulated_io_errors();
  PAGERTRACE(("CLOSE %d\n", PAGERID(pPager)));
  IOTRACE(("CLOSE %p\n", pPager))
  sqlite3OsClose(pPager->fd);
  sqlite3PageFree(pPager->pTmpSpace);
  sqlite3PcacheClose(pPager->pPCache);

#ifdef SQLITE_HAS_CODEC
  if( pPager->xCodecFree ) pPager->xCodecFree(pPager->pCodec);
#endif

  assert( !pPager->aSavepoint && !pPager->pInJournal );
  assert( !isOpen(pPager->jfd) && !isOpen(pPager->sjfd) );

  sqlite3_free(pPager);
  return SQLITE_OK;
}

#if !defined(NDEBUG) || defined(SQLITE_TEST)
/*
** Return the page number for page pPg.
*/
SQLITE_PRIVATE Pgno sqlite3PagerPagenumber(DbPage *pPg){
  return pPg->pgno;
}
#endif

/*
** Increment the reference count for page pPg.
*/
SQLITE_PRIVATE void sqlite3PagerRef(DbPage *pPg){
  sqlite3PcacheRef(pPg);
}

/*
** Sync the journal. In other words, make sure all the pages that have
** been written to the journal have actually reached the surface of the
** disk and can be restored in the event of a hot-journal rollback.
**
** If the Pager.needSync flag is not set, then this function is a
** no-op. Otherwise, the actions required depend on the journal-mode
** and the device characteristics of the the file-system, as follows:
**
**   * If the journal file is an in-memory journal file, no action need
**     be taken.
**
**   * Otherwise, if the device does not support the SAFE_APPEND property,
**     then the nRec field of the most recently written journal header
**     is updated to contain the number of journal records that have
**     been written following it. If the pager is operating in full-sync
**     mode, then the journal file is synced before this field is updated.
**
**   * If the device does not support the SEQUENTIAL property, then
**     journal file is synced.
**
** Or, in pseudo-code:
**
**   if( NOT <in-memory journal> ){
**     if( NOT SAFE_APPEND ){
**       if( <full-sync mode> ) xSync(<journal file>);
**       <update nRec field>
**     }
**     if( NOT SEQUENTIAL ) xSync(<journal file>);
**   }
**
** The Pager.needSync flag is never be set for temporary files, or any
** file operating in no-sync mode (Pager.noSync set to non-zero).
**
** If successful, this routine clears the PGHDR_NEED_SYNC flag of every
** page currently held in memory before returning SQLITE_OK. If an IO
** error is encountered, then the IO error code is returned to the caller.
*/
static int syncJournal(Pager *pPager){
  if( pPager->needSync ){
    assert( !pPager->tempFile );
    if( pPager->journalMode!=PAGER_JOURNALMODE_MEMORY ){
      int rc;                              /* Return code */
      const int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
      assert( isOpen(pPager->jfd) );

      if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
        /* This block deals with an obscure problem. If the last connection
        ** that wrote to this database was operating in persistent-journal
        ** mode, then the journal file may at this point actually be larger
        ** than Pager.journalOff bytes. If the next thing in the journal
        ** file happens to be a journal-header (written as part of the
        ** previous connections transaction), and a crash or power-failure
        ** occurs after nRec is updated but before this connection writes
        ** anything else to the journal file (or commits/rolls back its
        ** transaction), then SQLite may become confused when doing the
        ** hot-journal rollback following recovery. It may roll back all
        ** of this connections data, then proceed to rolling back the old,
        ** out-of-date data that follows it. Database corruption.
        **
        ** To work around this, if the journal file does appear to contain
        ** a valid header following Pager.journalOff, then write a 0x00
        ** byte to the start of it to prevent it from being recognized.
        **
        ** Variable iNextHdrOffset is set to the offset at which this
        ** problematic header will occur, if it exists. aMagic is used
        ** as a temporary buffer to inspect the first couple of bytes of
        ** the potential journal header.
        */
        i64 iNextHdrOffset;
        u8 aMagic[8];
	u8 zHeader[sizeof(aJournalMagic)+4];

	memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
	put32bits(&zHeader[sizeof(aJournalMagic)], pPager->nRec);

        iNextHdrOffset = journalHdrOffset(pPager);
        rc = sqlite3OsRead(pPager->jfd, aMagic, 8, iNextHdrOffset);
        if( rc==SQLITE_OK && 0==memcmp(aMagic, aJournalMagic, 8) ){
          static const u8 zerobyte = 0;
          rc = sqlite3OsWrite(pPager->jfd, &zerobyte, 1, iNextHdrOffset);
        }
        if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
          return rc;
        }

        /* Write the nRec value into the journal file header. If in
        ** full-synchronous mode, sync the journal first. This ensures that
        ** all data has really hit the disk before nRec is updated to mark
        ** it as a candidate for rollback.
        **
        ** This is not required if the persistent media supports the
        ** SAFE_APPEND property. Because in this case it is not possible
        ** for garbage data to be appended to the file, the nRec field
        ** is populated with 0xFFFFFFFF when the journal header is written
        ** and never needs to be updated.
        */
        if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
          PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
          IOTRACE(("JSYNC %p\n", pPager))
          rc = sqlite3OsSync(pPager->jfd, pPager->sync_flags);
          if( rc!=SQLITE_OK ) return rc;
        }
        IOTRACE(("JHDR %p %lld\n", pPager, pPager->journalHdr));
        rc = sqlite3OsWrite(
            pPager->jfd, zHeader, sizeof(zHeader), pPager->journalHdr
	);
        if( rc!=SQLITE_OK ) return rc;
      }
      if( 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
        PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
        IOTRACE(("JSYNC %p\n", pPager))
        rc = sqlite3OsSync(pPager->jfd, pPager->sync_flags|
          (pPager->sync_flags==SQLITE_SYNC_FULL?SQLITE_SYNC_DATAONLY:0)
        );
        if( rc!=SQLITE_OK ) return rc;
      }
    }

    /* The journal file was just successfully synced. Set Pager.needSync
    ** to zero and clear the PGHDR_NEED_SYNC flag on all pagess.
    */
    pPager->needSync = 0;
    pPager->journalStarted = 1;
    sqlite3PcacheClearSyncFlags(pPager->pPCache);
  }

  return SQLITE_OK;
}

/*
** The argument is the first in a linked list of dirty pages connected
** by the PgHdr.pDirty pointer. This function writes each one of the
** in-memory pages in the list to the database file. The argument may
** be NULL, representing an empty list. In this case this function is
** a no-op.
**
** The pager must hold at least a RESERVED lock when this function
** is called. Before writing anything to the database file, this lock
** is upgraded to an EXCLUSIVE lock. If the lock cannot be obtained,
** SQLITE_BUSY is returned and no data is written to the database file.
**