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      1 /* zlib.h -- interface of the 'zlib' general purpose compression library
      2   version 1.2.3.3, October 2nd, 2006
      3 
      4   Copyright (C) 1995-2006 Jean-loup Gailly and Mark Adler
      5 
      6   This software is provided 'as-is', without any express or implied
      7   warranty.  In no event will the authors be held liable for any damages
      8   arising from the use of this software.
      9 
     10   Permission is granted to anyone to use this software for any purpose,
     11   including commercial applications, and to alter it and redistribute it
     12   freely, subject to the following restrictions:
     13 
     14   1. The origin of this software must not be misrepresented; you must not
     15      claim that you wrote the original software. If you use this software
     16      in a product, an acknowledgment in the product documentation would be
     17      appreciated but is not required.
     18   2. Altered source versions must be plainly marked as such, and must not be
     19      misrepresented as being the original software.
     20   3. This notice may not be removed or altered from any source distribution.
     21 
     22   Jean-loup Gailly        Mark Adler
     23   jloup (at) gzip.org          madler (at) alumni.caltech.edu
     24 
     25 
     26   The data format used by the zlib library is described by RFCs (Request for
     27   Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
     28   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
     29 */
     30 
     31 #ifndef ZLIB_H
     32 #define ZLIB_H
     33 
     34 #include "zconf.h"
     35 
     36 #ifdef __cplusplus
     37 extern "C" {
     38 #endif
     39 
     40 #define ZLIB_VERSION "1.2.3.3"
     41 #define ZLIB_VERNUM 0x1233
     42 #define ZLIB_VER_MAJOR 1
     43 #define ZLIB_VER_MINOR 2
     44 #define ZLIB_VER_REVISION 3
     45 
     46 /*
     47      The 'zlib' compression library provides in-memory compression and
     48   decompression functions, including integrity checks of the uncompressed
     49   data.  This version of the library supports only one compression method
     50   (deflation) but other algorithms will be added later and will have the same
     51   stream interface.
     52 
     53      Compression can be done in a single step if the buffers are large
     54   enough (for example if an input file is mmap'ed), or can be done by
     55   repeated calls of the compression function.  In the latter case, the
     56   application must provide more input and/or consume the output
     57   (providing more output space) before each call.
     58 
     59      The compressed data format used by default by the in-memory functions is
     60   the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
     61   around a deflate stream, which is itself documented in RFC 1951.
     62 
     63      The library also supports reading and writing files in gzip (.gz) format
     64   with an interface similar to that of stdio using the functions that start
     65   with "gz".  The gzip format is different from the zlib format.  gzip is a
     66   gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
     67 
     68      This library can optionally read and write gzip streams in memory as well.
     69 
     70      The zlib format was designed to be compact and fast for use in memory
     71   and on communications channels.  The gzip format was designed for single-
     72   file compression on file systems, has a larger header than zlib to maintain
     73   directory information, and uses a different, slower check method than zlib.
     74 
     75      The library does not install any signal handler. The decoder checks
     76   the consistency of the compressed data, so the library should never
     77   crash even in case of corrupted input.
     78 */
     79 
     80 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
     81 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
     82 
     83 struct internal_state;
     84 
     85 typedef struct z_stream_s {
     86     Bytef    *next_in;  /* next input byte */
     87     uInt     avail_in;  /* number of bytes available at next_in */
     88     uLong    total_in;  /* total nb of input bytes read so far */
     89 
     90     Bytef    *next_out; /* next output byte should be put there */
     91     uInt     avail_out; /* remaining free space at next_out */
     92     uLong    total_out; /* total nb of bytes output so far */
     93 
     94     char     *msg;      /* last error message, NULL if no error */
     95     struct internal_state FAR *state; /* not visible by applications */
     96 
     97     alloc_func zalloc;  /* used to allocate the internal state */
     98     free_func  zfree;   /* used to free the internal state */
     99     voidpf     opaque;  /* private data object passed to zalloc and zfree */
    100 
    101     int     data_type;  /* best guess about the data type: binary or text */
    102     uLong   adler;      /* adler32 value of the uncompressed data */
    103     uLong   reserved;   /* reserved for future use */
    104 } z_stream;
    105 
    106 typedef z_stream FAR *z_streamp;
    107 
    108 /*
    109      gzip header information passed to and from zlib routines.  See RFC 1952
    110   for more details on the meanings of these fields.
    111 */
    112 typedef struct gz_header_s {
    113     int     text;       /* true if compressed data believed to be text */
    114     uLong   time;       /* modification time */
    115     int     xflags;     /* extra flags (not used when writing a gzip file) */
    116     int     os;         /* operating system */
    117     Bytef   *extra;     /* pointer to extra field or Z_NULL if none */
    118     uInt    extra_len;  /* extra field length (valid if extra != Z_NULL) */
    119     uInt    extra_max;  /* space at extra (only when reading header) */
    120     Bytef   *name;      /* pointer to zero-terminated file name or Z_NULL */
    121     uInt    name_max;   /* space at name (only when reading header) */
    122     Bytef   *comment;   /* pointer to zero-terminated comment or Z_NULL */
    123     uInt    comm_max;   /* space at comment (only when reading header) */
    124     int     hcrc;       /* true if there was or will be a header crc */
    125     int     done;       /* true when done reading gzip header (not used
    126                            when writing a gzip file) */
    127 } gz_header;
    128 
    129 typedef gz_header FAR *gz_headerp;
    130 
    131 /*
    132    The application must update next_in and avail_in when avail_in has
    133    dropped to zero. It must update next_out and avail_out when avail_out
    134    has dropped to zero. The application must initialize zalloc, zfree and
    135    opaque before calling the init function. All other fields are set by the
    136    compression library and must not be updated by the application.
    137 
    138    The opaque value provided by the application will be passed as the first
    139    parameter for calls of zalloc and zfree. This can be useful for custom
    140    memory management. The compression library attaches no meaning to the
    141    opaque value.
    142 
    143    zalloc must return Z_NULL if there is not enough memory for the object.
    144    If zlib is used in a multi-threaded application, zalloc and zfree must be
    145    thread safe.
    146 
    147    On 16-bit systems, the functions zalloc and zfree must be able to allocate
    148    exactly 65536 bytes, but will not be required to allocate more than this
    149    if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
    150    pointers returned by zalloc for objects of exactly 65536 bytes *must*
    151    have their offset normalized to zero. The default allocation function
    152    provided by this library ensures this (see zutil.c). To reduce memory
    153    requirements and avoid any allocation of 64K objects, at the expense of
    154    compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
    155 
    156    The fields total_in and total_out can be used for statistics or
    157    progress reports. After compression, total_in holds the total size of
    158    the uncompressed data and may be saved for use in the decompressor
    159    (particularly if the decompressor wants to decompress everything in
    160    a single step).
    161 */
    162 
    163                         /* constants */
    164 
    165 #define Z_NO_FLUSH      0
    166 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
    167 #define Z_SYNC_FLUSH    2
    168 #define Z_FULL_FLUSH    3
    169 #define Z_FINISH        4
    170 #define Z_BLOCK         5
    171 /* Allowed flush values; see deflate() and inflate() below for details */
    172 
    173 #define Z_OK            0
    174 #define Z_STREAM_END    1
    175 #define Z_NEED_DICT     2
    176 #define Z_ERRNO        (-1)
    177 #define Z_STREAM_ERROR (-2)
    178 #define Z_DATA_ERROR   (-3)
    179 #define Z_MEM_ERROR    (-4)
    180 #define Z_BUF_ERROR    (-5)
    181 #define Z_VERSION_ERROR (-6)
    182 /* Return codes for the compression/decompression functions. Negative
    183  * values are errors, positive values are used for special but normal events.
    184  */
    185 
    186 #define Z_NO_COMPRESSION         0
    187 #define Z_BEST_SPEED             1
    188 #define Z_BEST_COMPRESSION       9
    189 #define Z_DEFAULT_COMPRESSION  (-1)
    190 /* compression levels */
    191 
    192 #define Z_FILTERED            1
    193 #define Z_HUFFMAN_ONLY        2
    194 #define Z_RLE                 3
    195 #define Z_FIXED               4
    196 #define Z_DEFAULT_STRATEGY    0
    197 /* compression strategy; see deflateInit2() below for details */
    198 
    199 #define Z_BINARY   0
    200 #define Z_TEXT     1
    201 #define Z_ASCII    Z_TEXT   /* for compatibility with 1.2.2 and earlier */
    202 #define Z_UNKNOWN  2
    203 /* Possible values of the data_type field (though see inflate()) */
    204 
    205 #define Z_DEFLATED   8
    206 /* The deflate compression method (the only one supported in this version) */
    207 
    208 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
    209 
    210 #define zlib_version zlibVersion()
    211 /* for compatibility with versions < 1.0.2 */
    212 
    213                         /* basic functions */
    214 
    215 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
    216 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
    217    If the first character differs, the library code actually used is
    218    not compatible with the zlib.h header file used by the application.
    219    This check is automatically made by deflateInit and inflateInit.
    220  */
    221 
    222 /*
    223 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
    224 
    225      Initializes the internal stream state for compression. The fields
    226    zalloc, zfree and opaque must be initialized before by the caller.
    227    If zalloc and zfree are set to Z_NULL, deflateInit updates them to
    228    use default allocation functions.
    229 
    230      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
    231    1 gives best speed, 9 gives best compression, 0 gives no compression at
    232    all (the input data is simply copied a block at a time).
    233    Z_DEFAULT_COMPRESSION requests a default compromise between speed and
    234    compression (currently equivalent to level 6).
    235 
    236      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
    237    enough memory, Z_STREAM_ERROR if level is not a valid compression level,
    238    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
    239    with the version assumed by the caller (ZLIB_VERSION).
    240    msg is set to null if there is no error message.  deflateInit does not
    241    perform any compression: this will be done by deflate().
    242 */
    243 
    244 
    245 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
    246 /*
    247     deflate compresses as much data as possible, and stops when the input
    248   buffer becomes empty or the output buffer becomes full. It may introduce some
    249   output latency (reading input without producing any output) except when
    250   forced to flush.
    251 
    252     The detailed semantics are as follows. deflate performs one or both of the
    253   following actions:
    254 
    255   - Compress more input starting at next_in and update next_in and avail_in
    256     accordingly. If not all input can be processed (because there is not
    257     enough room in the output buffer), next_in and avail_in are updated and
    258     processing will resume at this point for the next call of deflate().
    259 
    260   - Provide more output starting at next_out and update next_out and avail_out
    261     accordingly. This action is forced if the parameter flush is non zero.
    262     Forcing flush frequently degrades the compression ratio, so this parameter
    263     should be set only when necessary (in interactive applications).
    264     Some output may be provided even if flush is not set.
    265 
    266   Before the call of deflate(), the application should ensure that at least
    267   one of the actions is possible, by providing more input and/or consuming
    268   more output, and updating avail_in or avail_out accordingly; avail_out
    269   should never be zero before the call. The application can consume the
    270   compressed output when it wants, for example when the output buffer is full
    271   (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
    272   and with zero avail_out, it must be called again after making room in the
    273   output buffer because there might be more output pending.
    274 
    275     Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
    276   decide how much data to accumualte before producing output, in order to
    277   maximize compression.
    278 
    279     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
    280   flushed to the output buffer and the output is aligned on a byte boundary, so
    281   that the decompressor can get all input data available so far. (In particular
    282   avail_in is zero after the call if enough output space has been provided
    283   before the call.)  Flushing may degrade compression for some compression
    284   algorithms and so it should be used only when necessary.
    285 
    286     If flush is set to Z_FULL_FLUSH, all output is flushed as with
    287   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
    288   restart from this point if previous compressed data has been damaged or if
    289   random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
    290   compression.
    291 
    292     If deflate returns with avail_out == 0, this function must be called again
    293   with the same value of the flush parameter and more output space (updated
    294   avail_out), until the flush is complete (deflate returns with non-zero
    295   avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
    296   avail_out is greater than six to avoid repeated flush markers due to
    297   avail_out == 0 on return.
    298 
    299     If the parameter flush is set to Z_FINISH, pending input is processed,
    300   pending output is flushed and deflate returns with Z_STREAM_END if there
    301   was enough output space; if deflate returns with Z_OK, this function must be
    302   called again with Z_FINISH and more output space (updated avail_out) but no
    303   more input data, until it returns with Z_STREAM_END or an error. After
    304   deflate has returned Z_STREAM_END, the only possible operations on the
    305   stream are deflateReset or deflateEnd.
    306 
    307     Z_FINISH can be used immediately after deflateInit if all the compression
    308   is to be done in a single step. In this case, avail_out must be at least
    309   the value returned by deflateBound (see below). If deflate does not return
    310   Z_STREAM_END, then it must be called again as described above.
    311 
    312     deflate() sets strm->adler to the adler32 checksum of all input read
    313   so far (that is, total_in bytes).
    314 
    315     deflate() may update strm->data_type if it can make a good guess about
    316   the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered
    317   binary. This field is only for information purposes and does not affect
    318   the compression algorithm in any manner.
    319 
    320     deflate() returns Z_OK if some progress has been made (more input
    321   processed or more output produced), Z_STREAM_END if all input has been
    322   consumed and all output has been produced (only when flush is set to
    323   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
    324   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
    325   (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
    326   fatal, and deflate() can be called again with more input and more output
    327   space to continue compressing.
    328 */
    329 
    330 
    331 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
    332 /*
    333      All dynamically allocated data structures for this stream are freed.
    334    This function discards any unprocessed input and does not flush any
    335    pending output.
    336 
    337      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
    338    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
    339    prematurely (some input or output was discarded). In the error case,
    340    msg may be set but then points to a static string (which must not be
    341    deallocated).
    342 */
    343 
    344 
    345 /*
    346 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
    347 
    348      Initializes the internal stream state for decompression. The fields
    349    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
    350    the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
    351    value depends on the compression method), inflateInit determines the
    352    compression method from the zlib header and allocates all data structures
    353    accordingly; otherwise the allocation will be deferred to the first call of
    354    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
    355    use default allocation functions.
    356 
    357      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
    358    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
    359    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
    360    invalid, such as a null pointer to the structure.  msg is set to null if
    361    there is no error message. inflateInit does not perform any decompression
    362    apart from possibly reading the zlib header if present: actual decompression
    363    will be done by inflate().  (So next_in and avail_in may be modified, but
    364    next_out and avail_out are unused and unchanged.)  The current
    365    implementation of inflateInit() does not process any header information --
    366    that is deferred until inflate() is called.
    367 */
    368 
    369 
    370 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
    371 /*
    372     inflate decompresses as much data as possible, and stops when the input
    373   buffer becomes empty or the output buffer becomes full. It may introduce
    374   some output latency (reading input without producing any output) except when
    375   forced to flush.
    376 
    377   The detailed semantics are as follows. inflate performs one or both of the
    378   following actions:
    379 
    380   - Decompress more input starting at next_in and update next_in and avail_in
    381     accordingly. If not all input can be processed (because there is not
    382     enough room in the output buffer), next_in is updated and processing
    383     will resume at this point for the next call of inflate().
    384 
    385   - Provide more output starting at next_out and update next_out and avail_out
    386     accordingly.  inflate() provides as much output as possible, until there
    387     is no more input data or no more space in the output buffer (see below
    388     about the flush parameter).
    389 
    390   Before the call of inflate(), the application should ensure that at least
    391   one of the actions is possible, by providing more input and/or consuming
    392   more output, and updating the next_* and avail_* values accordingly.
    393   The application can consume the uncompressed output when it wants, for
    394   example when the output buffer is full (avail_out == 0), or after each
    395   call of inflate(). If inflate returns Z_OK and with zero avail_out, it
    396   must be called again after making room in the output buffer because there
    397   might be more output pending.
    398 
    399     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
    400   Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
    401   output as possible to the output buffer. Z_BLOCK requests that inflate() stop
    402   if and when it gets to the next deflate block boundary. When decoding the
    403   zlib or gzip format, this will cause inflate() to return immediately after
    404   the header and before the first block. When doing a raw inflate, inflate()
    405   will go ahead and process the first block, and will return when it gets to
    406   the end of that block, or when it runs out of data.
    407 
    408     The Z_BLOCK option assists in appending to or combining deflate streams.
    409   Also to assist in this, on return inflate() will set strm->data_type to the
    410   number of unused bits in the last byte taken from strm->next_in, plus 64
    411   if inflate() is currently decoding the last block in the deflate stream,
    412   plus 128 if inflate() returned immediately after decoding an end-of-block
    413   code or decoding the complete header up to just before the first byte of the
    414   deflate stream. The end-of-block will not be indicated until all of the
    415   uncompressed data from that block has been written to strm->next_out.  The
    416   number of unused bits may in general be greater than seven, except when
    417   bit 7 of data_type is set, in which case the number of unused bits will be
    418   less than eight.
    419 
    420     inflate() should normally be called until it returns Z_STREAM_END or an
    421   error. However if all decompression is to be performed in a single step
    422   (a single call of inflate), the parameter flush should be set to
    423   Z_FINISH. In this case all pending input is processed and all pending
    424   output is flushed; avail_out must be large enough to hold all the
    425   uncompressed data. (The size of the uncompressed data may have been saved
    426   by the compressor for this purpose.) The next operation on this stream must
    427   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
    428   is never required, but can be used to inform inflate that a faster approach
    429   may be used for the single inflate() call.
    430 
    431      In this implementation, inflate() always flushes as much output as
    432   possible to the output buffer, and always uses the faster approach on the
    433   first call. So the only effect of the flush parameter in this implementation
    434   is on the return value of inflate(), as noted below, or when it returns early
    435   because Z_BLOCK is used.
    436 
    437      If a preset dictionary is needed after this call (see inflateSetDictionary
    438   below), inflate sets strm->adler to the adler32 checksum of the dictionary
    439   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
    440   strm->adler to the adler32 checksum of all output produced so far (that is,
    441   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
    442   below. At the end of the stream, inflate() checks that its computed adler32
    443   checksum is equal to that saved by the compressor and returns Z_STREAM_END
    444   only if the checksum is correct.
    445 
    446     inflate() will decompress and check either zlib-wrapped or gzip-wrapped
    447   deflate data.  The header type is detected automatically.  Any information
    448   contained in the gzip header is not retained, so applications that need that
    449   information should instead use raw inflate, see inflateInit2() below, or
    450   inflateBack() and perform their own processing of the gzip header and
    451   trailer.
    452 
    453     inflate() returns Z_OK if some progress has been made (more input processed
    454   or more output produced), Z_STREAM_END if the end of the compressed data has
    455   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
    456   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
    457   corrupted (input stream not conforming to the zlib format or incorrect check
    458   value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
    459   if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
    460   Z_BUF_ERROR if no progress is possible or if there was not enough room in the
    461   output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
    462   inflate() can be called again with more input and more output space to
    463   continue decompressing. If Z_DATA_ERROR is returned, the application may then
    464   call inflateSync() to look for a good compression block if a partial recovery
    465   of the data is desired.
    466 */
    467 
    468 
    469 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
    470 /*
    471      All dynamically allocated data structures for this stream are freed.
    472    This function discards any unprocessed input and does not flush any
    473    pending output.
    474 
    475      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
    476    was inconsistent. In the error case, msg may be set but then points to a
    477    static string (which must not be deallocated).
    478 */
    479 
    480                         /* Advanced functions */
    481 
    482 /*
    483     The following functions are needed only in some special applications.
    484 */
    485 
    486 /*
    487 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
    488                                      int  level,
    489                                      int  method,
    490                                      int  windowBits,
    491                                      int  memLevel,
    492                                      int  strategy));
    493 
    494      This is another version of deflateInit with more compression options. The
    495    fields next_in, zalloc, zfree and opaque must be initialized before by
    496    the caller.
    497 
    498      The method parameter is the compression method. It must be Z_DEFLATED in
    499    this version of the library.
    500 
    501      The windowBits parameter is the base two logarithm of the window size
    502    (the size of the history buffer). It should be in the range 8..15 for this
    503    version of the library. Larger values of this parameter result in better
    504    compression at the expense of memory usage. The default value is 15 if
    505    deflateInit is used instead.
    506 
    507      windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
    508    determines the window size. deflate() will then generate raw deflate data
    509    with no zlib header or trailer, and will not compute an adler32 check value.
    510 
    511      windowBits can also be greater than 15 for optional gzip encoding. Add
    512    16 to windowBits to write a simple gzip header and trailer around the
    513    compressed data instead of a zlib wrapper. The gzip header will have no
    514    file name, no extra data, no comment, no modification time (set to zero),
    515    no header crc, and the operating system will be set to 255 (unknown).  If a
    516    gzip stream is being written, strm->adler is a crc32 instead of an adler32.
    517 
    518      The memLevel parameter specifies how much memory should be allocated
    519    for the internal compression state. memLevel=1 uses minimum memory but
    520    is slow and reduces compression ratio; memLevel=9 uses maximum memory
    521    for optimal speed. The default value is 8. See zconf.h for total memory
    522    usage as a function of windowBits and memLevel.
    523 
    524      The strategy parameter is used to tune the compression algorithm. Use the
    525    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
    526    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
    527    string match), or Z_RLE to limit match distances to one (run-length
    528    encoding). Filtered data consists mostly of small values with a somewhat
    529    random distribution. In this case, the compression algorithm is tuned to
    530    compress them better. The effect of Z_FILTERED is to force more Huffman
    531    coding and less string matching; it is somewhat intermediate between
    532    Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
    533    Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
    534    parameter only affects the compression ratio but not the correctness of the
    535    compressed output even if it is not set appropriately.  Z_FIXED prevents the
    536    use of dynamic Huffman codes, allowing for a simpler decoder for special
    537    applications.
    538 
    539       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
    540    memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
    541    method). msg is set to null if there is no error message.  deflateInit2 does
    542    not perform any compression: this will be done by deflate().
    543 */
    544 
    545 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
    546                                              const Bytef *dictionary,
    547                                              uInt  dictLength));
    548 /*
    549      Initializes the compression dictionary from the given byte sequence
    550    without producing any compressed output. This function must be called
    551    immediately after deflateInit, deflateInit2 or deflateReset, before any
    552    call of deflate. The compressor and decompressor must use exactly the same
    553    dictionary (see inflateSetDictionary).
    554 
    555      The dictionary should consist of strings (byte sequences) that are likely
    556    to be encountered later in the data to be compressed, with the most commonly
    557    used strings preferably put towards the end of the dictionary. Using a
    558    dictionary is most useful when the data to be compressed is short and can be
    559    predicted with good accuracy; the data can then be compressed better than
    560    with the default empty dictionary.
    561 
    562      Depending on the size of the compression data structures selected by
    563    deflateInit or deflateInit2, a part of the dictionary may in effect be
    564    discarded, for example if the dictionary is larger than the window size in
    565    deflate or deflate2. Thus the strings most likely to be useful should be
    566    put at the end of the dictionary, not at the front. In addition, the
    567    current implementation of deflate will use at most the window size minus
    568    262 bytes of the provided dictionary.
    569 
    570      Upon return of this function, strm->adler is set to the adler32 value
    571    of the dictionary; the decompressor may later use this value to determine
    572    which dictionary has been used by the compressor. (The adler32 value
    573    applies to the whole dictionary even if only a subset of the dictionary is
    574    actually used by the compressor.) If a raw deflate was requested, then the
    575    adler32 value is not computed and strm->adler is not set.
    576 
    577      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
    578    parameter is invalid (such as NULL dictionary) or the stream state is
    579    inconsistent (for example if deflate has already been called for this stream
    580    or if the compression method is bsort). deflateSetDictionary does not
    581    perform any compression: this will be done by deflate().
    582 */
    583 
    584 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
    585                                     z_streamp source));
    586 /*
    587      Sets the destination stream as a complete copy of the source stream.
    588 
    589      This function can be useful when several compression strategies will be
    590    tried, for example when there are several ways of pre-processing the input
    591    data with a filter. The streams that will be discarded should then be freed
    592    by calling deflateEnd.  Note that deflateCopy duplicates the internal
    593    compression state which can be quite large, so this strategy is slow and
    594    can consume lots of memory.
    595 
    596      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
    597    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
    598    (such as zalloc being NULL). msg is left unchanged in both source and
    599    destination.
    600 */
    601 
    602 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
    603 /*
    604      This function is equivalent to deflateEnd followed by deflateInit,
    605    but does not free and reallocate all the internal compression state.
    606    The stream will keep the same compression level and any other attributes
    607    that may have been set by deflateInit2.
    608 
    609       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
    610    stream state was inconsistent (such as zalloc or state being NULL).
    611 */
    612 
    613 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
    614                                       int level,
    615                                       int strategy));
    616 /*
    617      Dynamically update the compression level and compression strategy.  The
    618    interpretation of level and strategy is as in deflateInit2.  This can be
    619    used to switch between compression and straight copy of the input data, or
    620    to switch to a different kind of input data requiring a different
    621    strategy. If the compression level is changed, the input available so far
    622    is compressed with the old level (and may be flushed); the new level will
    623    take effect only at the next call of deflate().
    624 
    625      Before the call of deflateParams, the stream state must be set as for
    626    a call of deflate(), since the currently available input may have to
    627    be compressed and flushed. In particular, strm->avail_out must be non-zero.
    628 
    629      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
    630    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
    631    if strm->avail_out was zero.
    632 */
    633 
    634 ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
    635                                     int good_length,
    636                                     int max_lazy,
    637                                     int nice_length,
    638                                     int max_chain));
    639 /*
    640      Fine tune deflate's internal compression parameters.  This should only be
    641    used by someone who understands the algorithm used by zlib's deflate for
    642    searching for the best matching string, and even then only by the most
    643    fanatic optimizer trying to squeeze out the last compressed bit for their
    644    specific input data.  Read the deflate.c source code for the meaning of the
    645    max_lazy, good_length, nice_length, and max_chain parameters.
    646 
    647      deflateTune() can be called after deflateInit() or deflateInit2(), and
    648    returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
    649  */
    650 
    651 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
    652                                        uLong sourceLen));
    653 /*
    654      deflateBound() returns an upper bound on the compressed size after
    655    deflation of sourceLen bytes.  It must be called after deflateInit() or
    656    deflateInit2(), and after deflateSetHeader(), if used.  This would be used
    657    to allocate an output buffer for deflation in a single pass, and so would be
    658    called before deflate().
    659 */
    660 
    661 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
    662                                      int bits,
    663                                      int value));
    664 /*
    665      deflatePrime() inserts bits in the deflate output stream.  The intent
    666   is that this function is used to start off the deflate output with the
    667   bits leftover from a previous deflate stream when appending to it.  As such,
    668   this function can only be used for raw deflate, and must be used before the
    669   first deflate() call after a deflateInit2() or deflateReset().  bits must be
    670   less than or equal to 16, and that many of the least significant bits of
    671   value will be inserted in the output.
    672 
    673       deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
    674    stream state was inconsistent.
    675 */
    676 
    677 ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
    678                                          gz_headerp head));
    679 /*
    680       deflateSetHeader() provides gzip header information for when a gzip
    681    stream is requested by deflateInit2().  deflateSetHeader() may be called
    682    after deflateInit2() or deflateReset() and before the first call of
    683    deflate().  The text, time, os, extra field, name, and comment information
    684    in the provided gz_header structure are written to the gzip header (xflag is
    685    ignored -- the extra flags are set according to the compression level).  The
    686    caller must assure that, if not Z_NULL, name and comment are terminated with
    687    a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
    688    available there.  If hcrc is true, a gzip header crc is included.  Note that
    689    the current versions of the command-line version of gzip (up through version
    690    1.3.x) do not support header crc's, and will report that it is a "multi-part
    691    gzip file" and give up.
    692 
    693       If deflateSetHeader is not used, the default gzip header has text false,
    694    the time set to zero, and os set to 255, with no extra, name, or comment
    695    fields.  The gzip header is returned to the default state by deflateReset().
    696 
    697       deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
    698    stream state was inconsistent.
    699 */
    700 
    701 /*
    702 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
    703                                      int  windowBits));
    704 
    705      This is another version of inflateInit with an extra parameter. The
    706    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
    707    before by the caller.
    708 
    709      The windowBits parameter is the base two logarithm of the maximum window
    710    size (the size of the history buffer).  It should be in the range 8..15 for
    711    this version of the library. The default value is 15 if inflateInit is used
    712    instead. windowBits must be greater than or equal to the windowBits value
    713    provided to deflateInit2() while compressing, or it must be equal to 15 if
    714    deflateInit2() was not used. If a compressed stream with a larger window
    715    size is given as input, inflate() will return with the error code
    716    Z_DATA_ERROR instead of trying to allocate a larger window.
    717 
    718      windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
    719    determines the window size. inflate() will then process raw deflate data,
    720    not looking for a zlib or gzip header, not generating a check value, and not
    721    looking for any check values for comparison at the end of the stream. This
    722    is for use with other formats that use the deflate compressed data format
    723    such as zip.  Those formats provide their own check values. If a custom
    724    format is developed using the raw deflate format for compressed data, it is
    725    recommended that a check value such as an adler32 or a crc32 be applied to
    726    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
    727    most applications, the zlib format should be used as is. Note that comments
    728    above on the use in deflateInit2() applies to the magnitude of windowBits.
    729 
    730      windowBits can also be greater than 15 for optional gzip decoding. Add
    731    32 to windowBits to enable zlib and gzip decoding with automatic header
    732    detection, or add 16 to decode only the gzip format (the zlib format will
    733    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is
    734    a crc32 instead of an adler32.
    735 
    736      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
    737    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
    738    version assumed by the caller, or Z_STREAM_ERROR if the parameters are
    739    invalid, such as a null pointer to the structure.  msg is set to null if
    740    there is no error message. inflateInit2 does not perform any decompression
    741    apart from possibly reading the zlib header if present: actual decompression
    742    will be done by inflate().  (So next_in and avail_in may be modified, but
    743    next_out and avail_out are unused and unchanged.)  The current
    744    implementation of inflateInit2() does not process any header information --
    745    that is deferred until inflate() is called.
    746 */
    747 
    748 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
    749                                              const Bytef *dictionary,
    750                                              uInt  dictLength));
    751 /*
    752      Initializes the decompression dictionary from the given uncompressed byte
    753    sequence. This function must be called immediately after a call of inflate,
    754    if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
    755    can be determined from the adler32 value returned by that call of inflate.
    756    The compressor and decompressor must use exactly the same dictionary (see
    757    deflateSetDictionary).  For raw inflate, this function can be called
    758    immediately after inflateInit2() or inflateReset() and before any call of
    759    inflate() to set the dictionary.  The application must insure that the
    760    dictionary that was used for compression is provided.
    761 
    762      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
    763    parameter is invalid (such as NULL dictionary) or the stream state is
    764    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
    765    expected one (incorrect adler32 value). inflateSetDictionary does not
    766    perform any decompression: this will be done by subsequent calls of
    767    inflate().
    768 */
    769 
    770 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
    771 /*
    772     Skips invalid compressed data until a full flush point (see above the
    773   description of deflate with Z_FULL_FLUSH) can be found, or until all
    774   available input is skipped. No output is provided.
    775 
    776     inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
    777   if no more input was provided, Z_DATA_ERROR if no flush point has been found,
    778   or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
    779   case, the application may save the current current value of total_in which
    780   indicates where valid compressed data was found. In the error case, the
    781   application may repeatedly call inflateSync, providing more input each time,
    782   until success or end of the input data.
    783 */
    784 
    785 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
    786                                     z_streamp source));
    787 /*
    788      Sets the destination stream as a complete copy of the source stream.
    789 
    790      This function can be useful when randomly accessing a large stream.  The
    791    first pass through the stream can periodically record the inflate state,
    792    allowing restarting inflate at those points when randomly accessing the
    793    stream.
    794 
    795      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
    796    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
    797    (such as zalloc being NULL). msg is left unchanged in both source and
    798    destination.
    799 */
    800 
    801 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
    802 /*
    803      This function is equivalent to inflateEnd followed by inflateInit,
    804    but does not free and reallocate all the internal decompression state.
    805    The stream will keep attributes that may have been set by inflateInit2.
    806 
    807       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
    808    stream state was inconsistent (such as zalloc or state being NULL).
    809 */
    810 
    811 ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
    812                                      int bits,
    813                                      int value));
    814 /*
    815      This function inserts bits in the inflate input stream.  The intent is
    816   that this function is used to start inflating at a bit position in the
    817   middle of a byte.  The provided bits will be used before any bytes are used
    818   from next_in.  This function should only be used with raw inflate, and
    819   should be used before the first inflate() call after inflateInit2() or
    820   inflateReset().  bits must be less than or equal to 16, and that many of the
    821   least significant bits of value will be inserted in the input.
    822 
    823       inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
    824    stream state was inconsistent.
    825 */
    826 
    827 ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
    828                                          gz_headerp head));
    829 /*
    830       inflateGetHeader() requests that gzip header information be stored in the
    831    provided gz_header structure.  inflateGetHeader() may be called after
    832    inflateInit2() or inflateReset(), and before the first call of inflate().
    833    As inflate() processes the gzip stream, head->done is zero until the header
    834    is completed, at which time head->done is set to one.  If a zlib stream is
    835    being decoded, then head->done is set to -1 to indicate that there will be
    836    no gzip header information forthcoming.  Note that Z_BLOCK can be used to
    837    force inflate() to return immediately after header processing is complete
    838    and before any actual data is decompressed.
    839 
    840       The text, time, xflags, and os fields are filled in with the gzip header
    841    contents.  hcrc is set to true if there is a header CRC.  (The header CRC
    842    was valid if done is set to one.)  If extra is not Z_NULL, then extra_max
    843    contains the maximum number of bytes to write to extra.  Once done is true,
    844    extra_len contains the actual extra field length, and extra contains the
    845    extra field, or that field truncated if extra_max is less than extra_len.
    846    If name is not Z_NULL, then up to name_max characters are written there,
    847    terminated with a zero unless the length is greater than name_max.  If
    848    comment is not Z_NULL, then up to comm_max characters are written there,
    849    terminated with a zero unless the length is greater than comm_max.  When
    850    any of extra, name, or comment are not Z_NULL and the respective field is
    851    not present in the header, then that field is set to Z_NULL to signal its
    852    absence.  This allows the use of deflateSetHeader() with the returned
    853    structure to duplicate the header.  However if those fields are set to
    854    allocated memory, then the application will need to save those pointers
    855    elsewhere so that they can be eventually freed.
    856 
    857       If inflateGetHeader is not used, then the header information is simply
    858    discarded.  The header is always checked for validity, including the header
    859    CRC if present.  inflateReset() will reset the process to discard the header
    860    information.  The application would need to call inflateGetHeader() again to
    861    retrieve the header from the next gzip stream.
    862 
    863       inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
    864    stream state was inconsistent.
    865 */
    866 
    867 /*
    868 ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
    869                                         unsigned char FAR *window));
    870 
    871      Initialize the internal stream state for decompression using inflateBack()
    872    calls.  The fields zalloc, zfree and opaque in strm must be initialized
    873    before the call.  If zalloc and zfree are Z_NULL, then the default library-
    874    derived memory allocation routines are used.  windowBits is the base two
    875    logarithm of the window size, in the range 8..15.  window is a caller
    876    supplied buffer of that size.  Except for special applications where it is
    877    assured that deflate was used with small window sizes, windowBits must be 15
    878    and a 32K byte window must be supplied to be able to decompress general
    879    deflate streams.
    880 
    881      See inflateBack() for the usage of these routines.
    882 
    883      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
    884    the paramaters are invalid, Z_MEM_ERROR if the internal state could not
    885    be allocated, or Z_VERSION_ERROR if the version of the library does not
    886    match the version of the header file.
    887 */
    888 
    889 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
    890 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
    891 
    892 ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,
    893                                     in_func in, void FAR *in_desc,
    894                                     out_func out, void FAR *out_desc));
    895 /*
    896      inflateBack() does a raw inflate with a single call using a call-back
    897    interface for input and output.  This is more efficient than inflate() for
    898    file i/o applications in that it avoids copying between the output and the
    899    sliding window by simply making the window itself the output buffer.  This
    900    function trusts the application to not change the output buffer passed by
    901    the output function, at least until inflateBack() returns.
    902 
    903      inflateBackInit() must be called first to allocate the internal state
    904    and to initialize the state with the user-provided window buffer.
    905    inflateBack() may then be used multiple times to inflate a complete, raw
    906    deflate stream with each call.  inflateBackEnd() is then called to free
    907    the allocated state.
    908 
    909      A raw deflate stream is one with no zlib or gzip header or trailer.
    910    This routine would normally be used in a utility that reads zip or gzip
    911    files and writes out uncompressed files.  The utility would decode the
    912    header and process the trailer on its own, hence this routine expects
    913    only the raw deflate stream to decompress.  This is different from the
    914    normal behavior of inflate(), which expects either a zlib or gzip header and
    915    trailer around the deflate stream.
    916 
    917      inflateBack() uses two subroutines supplied by the caller that are then
    918    called by inflateBack() for input and output.  inflateBack() calls those
    919    routines until it reads a complete deflate stream and writes out all of the
    920    uncompressed data, or until it encounters an error.  The function's
    921    parameters and return types are defined above in the in_func and out_func
    922    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
    923    number of bytes of provided input, and a pointer to that input in buf.  If
    924    there is no input available, in() must return zero--buf is ignored in that
    925    case--and inflateBack() will return a buffer error.  inflateBack() will call
    926    out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].  out()
    927    should return zero on success, or non-zero on failure.  If out() returns
    928    non-zero, inflateBack() will return with an error.  Neither in() nor out()
    929    are permitted to change the contents of the window provided to
    930    inflateBackInit(), which is also the buffer that out() uses to write from.
    931    The length written by out() will be at most the window size.  Any non-zero
    932    amount of input may be provided by in().
    933 
    934      For convenience, inflateBack() can be provided input on the first call by
    935    setting strm->next_in and strm->avail_in.  If that input is exhausted, then
    936    in() will be called.  Therefore strm->next_in must be initialized before
    937    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
    938    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
    939    must also be initialized, and then if strm->avail_in is not zero, input will
    940    initially be taken from strm->next_in[0 .. strm->avail_in - 1].
    941 
    942      The in_desc and out_desc parameters of inflateBack() is passed as the
    943    first parameter of in() and out() respectively when they are called.  These
    944    descriptors can be optionally used to pass any information that the caller-
    945    supplied in() and out() functions need to do their job.
    946 
    947      On return, inflateBack() will set strm->next_in and strm->avail_in to
    948    pass back any unused input that was provided by the last in() call.  The
    949    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
    950    if in() or out() returned an error, Z_DATA_ERROR if there was a format
    951    error in the deflate stream (in which case strm->msg is set to indicate the
    952    nature of the error), or Z_STREAM_ERROR if the stream was not properly
    953    initialized.  In the case of Z_BUF_ERROR, an input or output error can be
    954    distinguished using strm->next_in which will be Z_NULL only if in() returned
    955    an error.  If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
    956    out() returning non-zero.  (in() will always be called before out(), so
    957    strm->next_in is assured to be defined if out() returns non-zero.)  Note
    958    that inflateBack() cannot return Z_OK.
    959 */
    960 
    961 ZEXTERN int ZEXPORT inflateBackEnd OF((z_streamp strm));
    962 /*
    963      All memory allocated by inflateBackInit() is freed.
    964 
    965      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
    966    state was inconsistent.
    967 */
    968 
    969 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
    970 /* Return flags indicating compile-time options.
    971 
    972     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
    973      1.0: size of uInt
    974      3.2: size of uLong
    975      5.4: size of voidpf (pointer)
    976      7.6: size of z_off_t
    977 
    978     Compiler, assembler, and debug options:
    979      8: DEBUG
    980      9: ASMV or ASMINF -- use ASM code
    981      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
    982      11: 0 (reserved)
    983 
    984     One-time table building (smaller code, but not thread-safe if true):
    985      12: BUILDFIXED -- build static block decoding tables when needed
    986      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
    987      14,15: 0 (reserved)
    988 
    989     Library content (indicates missing functionality):
    990      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
    991                           deflate code when not needed)
    992      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
    993                     and decode gzip streams (to avoid linking crc code)
    994      18-19: 0 (reserved)
    995 
    996     Operation variations (changes in library functionality):
    997      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
    998      21: FASTEST -- deflate algorithm with only one, lowest compression level
    999      22,23: 0 (reserved)
   1000 
   1001     The sprintf variant used by gzprintf (zero is best):
   1002      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
   1003      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
   1004      26: 0 = returns value, 1 = void -- 1 means inferred string length returned
   1005 
   1006     Remainder:
   1007      27-31: 0 (reserved)
   1008  */
   1009 
   1010 
   1011                         /* utility functions */
   1012 
   1013 /*
   1014      The following utility functions are implemented on top of the
   1015    basic stream-oriented functions. To simplify the interface, some
   1016    default options are assumed (compression level and memory usage,
   1017    standard memory allocation functions). The source code of these
   1018    utility functions can easily be modified if you need special options.
   1019 */
   1020 
   1021 ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
   1022                                  const Bytef *source, uLong sourceLen));
   1023 /*
   1024      Compresses the source buffer into the destination buffer.  sourceLen is
   1025    the byte length of the source buffer. Upon entry, destLen is the total
   1026    size of the destination buffer, which must be at least the value returned
   1027    by compressBound(sourceLen). Upon exit, destLen is the actual size of the
   1028    compressed buffer.
   1029      This function can be used to compress a whole file at once if the
   1030    input file is mmap'ed.
   1031      compress returns Z_OK if success, Z_MEM_ERROR if there was not
   1032    enough memory, Z_BUF_ERROR if there was not enough room in the output
   1033    buffer.
   1034 */
   1035 
   1036 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
   1037                                   const Bytef *source, uLong sourceLen,
   1038                                   int level));
   1039 /*
   1040      Compresses the source buffer into the destination buffer. The level
   1041    parameter has the same meaning as in deflateInit.  sourceLen is the byte
   1042    length of the source buffer. Upon entry, destLen is the total size of the
   1043    destination buffer, which must be at least the value returned by
   1044    compressBound(sourceLen). Upon exit, destLen is the actual size of the
   1045    compressed buffer.
   1046 
   1047      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
   1048    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
   1049    Z_STREAM_ERROR if the level parameter is invalid.
   1050 */
   1051 
   1052 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
   1053 /*
   1054      compressBound() returns an upper bound on the compressed size after
   1055    compress() or compress2() on sourceLen bytes.  It would be used before
   1056    a compress() or compress2() call to allocate the destination buffer.
   1057 */
   1058 
   1059 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
   1060                                    const Bytef *source, uLong sourceLen));
   1061 /*
   1062      Decompresses the source buffer into the destination buffer.  sourceLen is
   1063    the byte length of the source buffer. Upon entry, destLen is the total
   1064    size of the destination buffer, which must be large enough to hold the
   1065    entire uncompressed data. (The size of the uncompressed data must have
   1066    been saved previously by the compressor and transmitted to the decompressor
   1067    by some mechanism outside the scope of this compression library.)
   1068    Upon exit, destLen is the actual size of the compressed buffer.
   1069      This function can be used to decompress a whole file at once if the
   1070    input file is mmap'ed.
   1071 
   1072      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
   1073    enough memory, Z_BUF_ERROR if there was not enough room in the output
   1074    buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
   1075 */
   1076 
   1077 
   1078 typedef voidp gzFile;
   1079 
   1080 /*
   1081 ZEXTERN gzFile ZEXPORT gzopen  OF((const char *path, const char *mode));
   1082 
   1083      Opens a gzip (.gz) file for reading or writing. The mode parameter
   1084    is as in fopen ("rb" or "wb") but can also include a compression level
   1085    ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
   1086    Huffman only compression as in "wb1h", or 'R' for run-length encoding
   1087    as in "wb1R". (See the description of deflateInit2 for more information
   1088    about the strategy parameter.)
   1089 
   1090      gzopen can be used to read a file which is not in gzip format; in this
   1091    case gzread will directly read from the file without decompression.
   1092 
   1093      gzopen returns NULL if the file could not be opened or if there was
   1094    insufficient memory to allocate the (de)compression state; errno
   1095    can be checked to distinguish the two cases (if errno is zero, the
   1096    zlib error is Z_MEM_ERROR).  */
   1097 
   1098 ZEXTERN gzFile ZEXPORT gzdopen  OF((int fd, const char *mode));
   1099 /*
   1100      gzdopen() associates a gzFile with the file descriptor fd.  File
   1101    descriptors are obtained from calls like open, dup, creat, pipe or
   1102    fileno (in the file has been previously opened with fopen).
   1103    The mode parameter is as in gzopen.
   1104      The next call of gzclose on the returned gzFile will also close the
   1105    file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
   1106    descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
   1107      gzdopen returns NULL if there was insufficient memory to allocate
   1108    the (de)compression state.
   1109 */
   1110 
   1111 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
   1112 /*
   1113      Dynamically update the compression level or strategy. See the description
   1114    of deflateInit2 for the meaning of these parameters.
   1115      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
   1116    opened for writing.
   1117 */
   1118 
   1119 ZEXTERN int ZEXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));
   1120 /*
   1121      Reads the given number of uncompressed bytes from the compressed file.
   1122    If the input file was not in gzip format, gzread copies the given number
   1123    of bytes into the buffer.
   1124      gzread returns the number of uncompressed bytes actually read (0 for
   1125    end of file, -1 for error). */
   1126 
   1127 ZEXTERN int ZEXPORT    gzwrite OF((gzFile file,
   1128                                    voidpc buf, unsigned len));
   1129 /*
   1130      Writes the given number of uncompressed bytes into the compressed file.
   1131    gzwrite returns the number of uncompressed bytes actually written
   1132    (0 in case of error).
   1133 */
   1134 
   1135 ZEXTERN int ZEXPORTVA   gzprintf OF((gzFile file, const char *format, ...));
   1136 /*
   1137      Converts, formats, and writes the args to the compressed file under
   1138    control of the format string, as in fprintf. gzprintf returns the number of
   1139    uncompressed bytes actually written (0 in case of error).  The number of
   1140    uncompressed bytes written is limited to 4095. The caller should assure that
   1141    this limit is not exceeded. If it is exceeded, then gzprintf() will return
   1142    return an error (0) with nothing written. In this case, there may also be a
   1143    buffer overflow with unpredictable consequences, which is possible only if
   1144    zlib was compiled with the insecure functions sprintf() or vsprintf()
   1145    because the secure snprintf() or vsnprintf() functions were not available.
   1146 */
   1147 
   1148 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
   1149 /*
   1150       Writes the given null-terminated string to the compressed file, excluding
   1151    the terminating null character.
   1152       gzputs returns the number of characters written, or -1 in case of error.
   1153 */
   1154 
   1155 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
   1156 /*
   1157       Reads bytes from the compressed file until len-1 characters are read, or
   1158    a newline character is read and transferred to buf, or an end-of-file
   1159    condition is encountered.  The string is then terminated with a null
   1160    character.
   1161       gzgets returns buf, or Z_NULL in case of error.
   1162 */
   1163 
   1164 ZEXTERN int ZEXPORT    gzputc OF((gzFile file, int c));
   1165 /*
   1166       Writes c, converted to an unsigned char, into the compressed file.
   1167    gzputc returns the value that was written, or -1 in case of error.
   1168 */
   1169 
   1170 ZEXTERN int ZEXPORT    gzgetc OF((gzFile file));
   1171 /*
   1172       Reads one byte from the compressed file. gzgetc returns this byte
   1173    or -1 in case of end of file or error.
   1174 */
   1175 
   1176 ZEXTERN int ZEXPORT    gzungetc OF((int c, gzFile file));
   1177 /*
   1178       Push one character back onto the stream to be read again later.
   1179    Only one character of push-back is allowed.  gzungetc() returns the
   1180    character pushed, or -1 on failure.  gzungetc() will fail if a
   1181    character has been pushed but not read yet, or if c is -1. The pushed
   1182    character will be discarded if the stream is repositioned with gzseek()
   1183    or gzrewind().
   1184 */
   1185 
   1186 ZEXTERN int ZEXPORT    gzflush OF((gzFile file, int flush));
   1187 /*
   1188      Flushes all pending output into the compressed file. The parameter
   1189    flush is as in the deflate() function. The return value is the zlib
   1190    error number (see function gzerror below). gzflush returns Z_OK if
   1191    the flush parameter is Z_FINISH and all output could be flushed.
   1192      gzflush should be called only when strictly necessary because it can
   1193    degrade compression.
   1194 */
   1195 
   1196 /*
   1197 ZEXTERN z_off_t ZEXPORT    gzseek OF((gzFile file,
   1198                                       z_off_t offset, int whence));
   1199 
   1200       Sets the starting position for the next gzread or gzwrite on the
   1201    given compressed file. The offset represents a number of bytes in the
   1202    uncompressed data stream. The whence parameter is defined as in lseek(2);
   1203    the value SEEK_END is not supported.
   1204      If the file is opened for reading, this function is emulated but can be
   1205    extremely slow. If the file is opened for writing, only forward seeks are
   1206    supported; gzseek then compresses a sequence of zeroes up to the new
   1207    starting position.
   1208 
   1209       gzseek returns the resulting offset location as measured in bytes from
   1210    the beginning of the uncompressed stream, or -1 in case of error, in
   1211    particular if the file is opened for writing and the new starting position
   1212    would be before the current position.
   1213 */
   1214 
   1215 ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
   1216 /*
   1217      Rewinds the given file. This function is supported only for reading.
   1218 
   1219    gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
   1220 */
   1221 
   1222 /*
   1223 ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
   1224 
   1225      Returns the starting position for the next gzread or gzwrite on the
   1226    given compressed file. This position represents a number of bytes in the
   1227    uncompressed data stream.
   1228 
   1229    gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
   1230 */
   1231 
   1232 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
   1233 /*
   1234      Returns 1 when EOF has previously been detected reading the given
   1235    input stream, otherwise zero.
   1236 */
   1237 
   1238 ZEXTERN int ZEXPORT gzdirect OF((gzFile file));
   1239 /*
   1240      Returns 1 if file is being read directly without decompression, otherwise
   1241    zero.
   1242 */
   1243 
   1244 ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
   1245 /*
   1246      Flushes all pending output if necessary, closes the compressed file
   1247    and deallocates all the (de)compression state. The return value is the zlib
   1248    error number.  Note that once file is close, you cannot call gzerror with
   1249    file, since its structures have been deallocated.
   1250 */
   1251 
   1252 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
   1253 /*
   1254      Returns the error message for the last error which occurred on the
   1255    given compressed file. errnum is set to zlib error number. If an
   1256    error occurred in the file system and not in the compression library,
   1257    errnum is set to Z_ERRNO and the application may consult errno
   1258    to get the exact error code.
   1259 
   1260    The application must not modify the returned string and future calls to
   1261    this function may invalidate the returned string.
   1262 */
   1263 
   1264 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
   1265 /*
   1266      Clears the error and end-of-file flags for file. This is analogous to the
   1267    clearerr() function in stdio. This is useful for continuing to read a gzip
   1268    file that is being written concurrently.
   1269 */
   1270 
   1271                         /* checksum functions */
   1272 
   1273 /*
   1274      These functions are not related to compression but are exported
   1275    anyway because they might be useful in applications using the
   1276    compression library.
   1277 */
   1278 
   1279 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
   1280 /*
   1281      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
   1282    return the updated checksum. If buf is NULL, this function returns
   1283    the required initial value for the checksum.
   1284    An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
   1285    much faster. Usage example:
   1286 
   1287      uLong adler = adler32(0L, Z_NULL, 0);
   1288 
   1289      while (read_buffer(buffer, length) != EOF) {
   1290        adler = adler32(adler, buffer, length);
   1291      }
   1292      if (adler != original_adler) error();
   1293 */
   1294 
   1295 /*
   1296 ZEXTERN uLong ZEXPORT adler32_combine OF((uLong adler1, uLong adler2,
   1297                                           z_off_t len2));
   1298 
   1299      Combine two Adler-32 checksums into one.  For two sequences of bytes, seq1
   1300    and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
   1301    each, adler1 and adler2.  adler32_combine() returns the Adler-32 checksum of
   1302    seq1 and seq2 concatenated, requiring only adler1, adler2, and len2.
   1303 */
   1304 
   1305 ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
   1306 /*
   1307      Update a running CRC-32 with the bytes buf[0..len-1] and return the
   1308    updated CRC-32. If buf is NULL, this function returns the required initial
   1309    value for the for the crc. Pre- and post-conditioning (one's complement) is
   1310    performed within this function so it shouldn't be done by the application.
   1311    Usage example:
   1312 
   1313      uLong crc = crc32(0L, Z_NULL, 0);
   1314 
   1315      while (read_buffer(buffer, length) != EOF) {
   1316        crc = crc32(crc, buffer, length);
   1317      }
   1318      if (crc != original_crc) error();
   1319 */
   1320 
   1321 /*
   1322 ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2));
   1323 
   1324      Combine two CRC-32 check values into one.  For two sequences of bytes,
   1325    seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
   1326    calculated for each, crc1 and crc2.  crc32_combine() returns the CRC-32
   1327    check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
   1328    len2.
   1329 */
   1330 
   1331 
   1332                         /* various hacks, don't look :) */
   1333 
   1334 /* deflateInit and inflateInit are macros to allow checking the zlib version
   1335  * and the compiler's view of z_stream:
   1336  */
   1337 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
   1338                                      const char *version, int stream_size));
   1339 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
   1340                                      const char *version, int stream_size));
   1341 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
   1342                                       int windowBits, int memLevel,
   1343                                       int strategy, const char *version,
   1344                                       int stream_size));
   1345 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
   1346                                       const char *version, int stream_size));
   1347 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_streamp strm, int windowBits,
   1348                                          unsigned char FAR *window,
   1349                                          const char *version,
   1350                                          int stream_size));
   1351 #define deflateInit(strm, level) \
   1352         deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
   1353 #define inflateInit(strm) \
   1354         inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
   1355 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
   1356         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
   1357                       (strategy),           ZLIB_VERSION, sizeof(z_stream))
   1358 #define inflateInit2(strm, windowBits) \
   1359         inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
   1360 #define inflateBackInit(strm, windowBits, window) \
   1361         inflateBackInit_((strm), (windowBits), (window), \
   1362                                             ZLIB_VERSION, sizeof(z_stream))
   1363 
   1364 #if defined(_LARGEFILE64_SOURCE)
   1365     #define z_off64_t off64_t
   1366 #else
   1367     #if _FILE_OFFSET_BITS == 64
   1368         #define z_off64_t off_t
   1369     #endif
   1370 #endif
   1371 
   1372 #if defined(_LARGEFILE64_SOURCE) || _FILE_OFFSET_BITS == 64
   1373    ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *));
   1374    ZEXTERN z_off64_t ZEXPORT gzseek64 OF((gzFile, z_off64_t, int));
   1375    ZEXTERN z_off64_t ZEXPORT gztell64 OF((gzFile));
   1376    ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t));
   1377    ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t));
   1378 #endif
   1379 
   1380 #if _FILE_OFFSET_BITS == 64
   1381 #  define gzopen gzopen64
   1382 #  define gzseek gzseek64
   1383 #  define gztell gztell64
   1384 #  define adler32_combine adler32_combine64
   1385 #  define crc32_combine crc32_combine64
   1386 #else
   1387    ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *));
   1388    ZEXTERN z_off_t ZEXPORT gzseek OF((gzFile, z_off_t, int));
   1389    ZEXTERN z_off_t ZEXPORT gztell OF((gzFile));
   1390    ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t));
   1391    ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t));
   1392 #endif
   1393 
   1394 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
   1395     struct internal_state {int dummy;}; /* hack for buggy compilers */
   1396 #endif
   1397 
   1398 ZEXTERN const char   * ZEXPORT zError           OF((int));
   1399 ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
   1400 ZEXTERN const uLongf * ZEXPORT get_crc_table    OF((void));
   1401 ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
   1402 
   1403 #ifdef __cplusplus
   1404 }
   1405 #endif
   1406 
   1407 #endif /* ZLIB_H */
   1408