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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/logging.h"
      6 
      7 #if defined(OS_WIN)
      8 #include <io.h>
      9 #include <windows.h>
     10 typedef HANDLE FileHandle;
     11 typedef HANDLE MutexHandle;
     12 // Windows warns on using write().  It prefers _write().
     13 #define write(fd, buf, count) _write(fd, buf, static_cast<unsigned int>(count))
     14 // Windows doesn't define STDERR_FILENO.  Define it here.
     15 #define STDERR_FILENO 2
     16 #elif defined(OS_MACOSX)
     17 #include <mach/mach.h>
     18 #include <mach/mach_time.h>
     19 #include <mach-o/dyld.h>
     20 #elif defined(OS_POSIX)
     21 #if defined(OS_NACL)
     22 #include <sys/time.h> // timespec doesn't seem to be in <time.h>
     23 #else
     24 #include <sys/syscall.h>
     25 #endif
     26 #include <time.h>
     27 #endif
     28 
     29 #if defined(OS_POSIX)
     30 #include <errno.h>
     31 #include <pthread.h>
     32 #include <stdio.h>
     33 #include <stdlib.h>
     34 #include <string.h>
     35 #include <unistd.h>
     36 #define MAX_PATH PATH_MAX
     37 typedef FILE* FileHandle;
     38 typedef pthread_mutex_t* MutexHandle;
     39 #endif
     40 
     41 #include <algorithm>
     42 #include <cstring>
     43 #include <ctime>
     44 #include <iomanip>
     45 #include <ostream>
     46 
     47 #include "base/base_switches.h"
     48 #include "base/command_line.h"
     49 #include "base/debug/alias.h"
     50 #include "base/debug/debugger.h"
     51 #include "base/debug/stack_trace.h"
     52 #include "base/posix/eintr_wrapper.h"
     53 #include "base/strings/string_piece.h"
     54 #include "base/strings/utf_string_conversions.h"
     55 #include "base/synchronization/lock_impl.h"
     56 #include "base/threading/platform_thread.h"
     57 #include "base/vlog.h"
     58 #if defined(OS_POSIX)
     59 #include "base/safe_strerror_posix.h"
     60 #endif
     61 
     62 #if defined(OS_ANDROID)
     63 #include <android/log.h>
     64 #endif
     65 
     66 namespace logging {
     67 
     68 DcheckState g_dcheck_state = DISABLE_DCHECK_FOR_NON_OFFICIAL_RELEASE_BUILDS;
     69 
     70 DcheckState get_dcheck_state() {
     71   return g_dcheck_state;
     72 }
     73 
     74 void set_dcheck_state(DcheckState state) {
     75   g_dcheck_state = state;
     76 }
     77 
     78 namespace {
     79 
     80 VlogInfo* g_vlog_info = NULL;
     81 VlogInfo* g_vlog_info_prev = NULL;
     82 
     83 const char* const log_severity_names[LOG_NUM_SEVERITIES] = {
     84   "INFO", "WARNING", "ERROR", "ERROR_REPORT", "FATAL" };
     85 
     86 int min_log_level = 0;
     87 
     88 LoggingDestination logging_destination = LOG_DEFAULT;
     89 
     90 // For LOG_ERROR and above, always print to stderr.
     91 const int kAlwaysPrintErrorLevel = LOG_ERROR;
     92 
     93 // Which log file to use? This is initialized by InitLogging or
     94 // will be lazily initialized to the default value when it is
     95 // first needed.
     96 #if defined(OS_WIN)
     97 typedef std::wstring PathString;
     98 #else
     99 typedef std::string PathString;
    100 #endif
    101 PathString* log_file_name = NULL;
    102 
    103 // this file is lazily opened and the handle may be NULL
    104 FileHandle log_file = NULL;
    105 
    106 // what should be prepended to each message?
    107 bool log_process_id = false;
    108 bool log_thread_id = false;
    109 bool log_timestamp = true;
    110 bool log_tickcount = false;
    111 
    112 // Should we pop up fatal debug messages in a dialog?
    113 bool show_error_dialogs = false;
    114 
    115 // An assert handler override specified by the client to be called instead of
    116 // the debug message dialog and process termination.
    117 LogAssertHandlerFunction log_assert_handler = NULL;
    118 // An report handler override specified by the client to be called instead of
    119 // the debug message dialog.
    120 LogReportHandlerFunction log_report_handler = NULL;
    121 // A log message handler that gets notified of every log message we process.
    122 LogMessageHandlerFunction log_message_handler = NULL;
    123 
    124 // Helper functions to wrap platform differences.
    125 
    126 int32 CurrentProcessId() {
    127 #if defined(OS_WIN)
    128   return GetCurrentProcessId();
    129 #elif defined(OS_POSIX)
    130   return getpid();
    131 #endif
    132 }
    133 
    134 uint64 TickCount() {
    135 #if defined(OS_WIN)
    136   return GetTickCount();
    137 #elif defined(OS_MACOSX)
    138   return mach_absolute_time();
    139 #elif defined(OS_NACL)
    140   // NaCl sadly does not have _POSIX_TIMERS enabled in sys/features.h
    141   // So we have to use clock() for now.
    142   return clock();
    143 #elif defined(OS_POSIX)
    144   struct timespec ts;
    145   clock_gettime(CLOCK_MONOTONIC, &ts);
    146 
    147   uint64 absolute_micro =
    148     static_cast<int64>(ts.tv_sec) * 1000000 +
    149     static_cast<int64>(ts.tv_nsec) / 1000;
    150 
    151   return absolute_micro;
    152 #endif
    153 }
    154 
    155 void DeleteFilePath(const PathString& log_name) {
    156 #if defined(OS_WIN)
    157   DeleteFile(log_name.c_str());
    158 #elif defined (OS_NACL)
    159   // Do nothing; unlink() isn't supported on NaCl.
    160 #else
    161   unlink(log_name.c_str());
    162 #endif
    163 }
    164 
    165 PathString GetDefaultLogFile() {
    166 #if defined(OS_WIN)
    167   // On Windows we use the same path as the exe.
    168   wchar_t module_name[MAX_PATH];
    169   GetModuleFileName(NULL, module_name, MAX_PATH);
    170 
    171   PathString log_file = module_name;
    172   PathString::size_type last_backslash =
    173       log_file.rfind('\\', log_file.size());
    174   if (last_backslash != PathString::npos)
    175     log_file.erase(last_backslash + 1);
    176   log_file += L"debug.log";
    177   return log_file;
    178 #elif defined(OS_POSIX)
    179   // On other platforms we just use the current directory.
    180   return PathString("debug.log");
    181 #endif
    182 }
    183 
    184 // This class acts as a wrapper for locking the logging files.
    185 // LoggingLock::Init() should be called from the main thread before any logging
    186 // is done. Then whenever logging, be sure to have a local LoggingLock
    187 // instance on the stack. This will ensure that the lock is unlocked upon
    188 // exiting the frame.
    189 // LoggingLocks can not be nested.
    190 class LoggingLock {
    191  public:
    192   LoggingLock() {
    193     LockLogging();
    194   }
    195 
    196   ~LoggingLock() {
    197     UnlockLogging();
    198   }
    199 
    200   static void Init(LogLockingState lock_log, const PathChar* new_log_file) {
    201     if (initialized)
    202       return;
    203     lock_log_file = lock_log;
    204     if (lock_log_file == LOCK_LOG_FILE) {
    205 #if defined(OS_WIN)
    206       if (!log_mutex) {
    207         std::wstring safe_name;
    208         if (new_log_file)
    209           safe_name = new_log_file;
    210         else
    211           safe_name = GetDefaultLogFile();
    212         // \ is not a legal character in mutex names so we replace \ with /
    213         std::replace(safe_name.begin(), safe_name.end(), '\\', '/');
    214         std::wstring t(L"Global\\");
    215         t.append(safe_name);
    216         log_mutex = ::CreateMutex(NULL, FALSE, t.c_str());
    217 
    218         if (log_mutex == NULL) {
    219 #if DEBUG
    220           // Keep the error code for debugging
    221           int error = GetLastError();  // NOLINT
    222           base::debug::BreakDebugger();
    223 #endif
    224           // Return nicely without putting initialized to true.
    225           return;
    226         }
    227       }
    228 #endif
    229     } else {
    230       log_lock = new base::internal::LockImpl();
    231     }
    232     initialized = true;
    233   }
    234 
    235  private:
    236   static void LockLogging() {
    237     if (lock_log_file == LOCK_LOG_FILE) {
    238 #if defined(OS_WIN)
    239       ::WaitForSingleObject(log_mutex, INFINITE);
    240       // WaitForSingleObject could have returned WAIT_ABANDONED. We don't
    241       // abort the process here. UI tests might be crashy sometimes,
    242       // and aborting the test binary only makes the problem worse.
    243       // We also don't use LOG macros because that might lead to an infinite
    244       // loop. For more info see http://crbug.com/18028.
    245 #elif defined(OS_POSIX)
    246       pthread_mutex_lock(&log_mutex);
    247 #endif
    248     } else {
    249       // use the lock
    250       log_lock->Lock();
    251     }
    252   }
    253 
    254   static void UnlockLogging() {
    255     if (lock_log_file == LOCK_LOG_FILE) {
    256 #if defined(OS_WIN)
    257       ReleaseMutex(log_mutex);
    258 #elif defined(OS_POSIX)
    259       pthread_mutex_unlock(&log_mutex);
    260 #endif
    261     } else {
    262       log_lock->Unlock();
    263     }
    264   }
    265 
    266   // The lock is used if log file locking is false. It helps us avoid problems
    267   // with multiple threads writing to the log file at the same time.  Use
    268   // LockImpl directly instead of using Lock, because Lock makes logging calls.
    269   static base::internal::LockImpl* log_lock;
    270 
    271   // When we don't use a lock, we are using a global mutex. We need to do this
    272   // because LockFileEx is not thread safe.
    273 #if defined(OS_WIN)
    274   static MutexHandle log_mutex;
    275 #elif defined(OS_POSIX)
    276   static pthread_mutex_t log_mutex;
    277 #endif
    278 
    279   static bool initialized;
    280   static LogLockingState lock_log_file;
    281 };
    282 
    283 // static
    284 bool LoggingLock::initialized = false;
    285 // static
    286 base::internal::LockImpl* LoggingLock::log_lock = NULL;
    287 // static
    288 LogLockingState LoggingLock::lock_log_file = LOCK_LOG_FILE;
    289 
    290 #if defined(OS_WIN)
    291 // static
    292 MutexHandle LoggingLock::log_mutex = NULL;
    293 #elif defined(OS_POSIX)
    294 pthread_mutex_t LoggingLock::log_mutex = PTHREAD_MUTEX_INITIALIZER;
    295 #endif
    296 
    297 // Called by logging functions to ensure that debug_file is initialized
    298 // and can be used for writing. Returns false if the file could not be
    299 // initialized. debug_file will be NULL in this case.
    300 bool InitializeLogFileHandle() {
    301   if (log_file)
    302     return true;
    303 
    304   if (!log_file_name) {
    305     // Nobody has called InitLogging to specify a debug log file, so here we
    306     // initialize the log file name to a default.
    307     log_file_name = new PathString(GetDefaultLogFile());
    308   }
    309 
    310   if ((logging_destination & LOG_TO_FILE) != 0) {
    311 #if defined(OS_WIN)
    312     log_file = CreateFile(log_file_name->c_str(), GENERIC_WRITE,
    313                           FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,
    314                           OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
    315     if (log_file == INVALID_HANDLE_VALUE || log_file == NULL) {
    316       // try the current directory
    317       log_file = CreateFile(L".\\debug.log", GENERIC_WRITE,
    318                             FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,
    319                             OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
    320       if (log_file == INVALID_HANDLE_VALUE || log_file == NULL) {
    321         log_file = NULL;
    322         return false;
    323       }
    324     }
    325     SetFilePointer(log_file, 0, 0, FILE_END);
    326 #elif defined(OS_POSIX)
    327     log_file = fopen(log_file_name->c_str(), "a");
    328     if (log_file == NULL)
    329       return false;
    330 #endif
    331   }
    332 
    333   return true;
    334 }
    335 
    336 void CloseFile(FileHandle log) {
    337 #if defined(OS_WIN)
    338   CloseHandle(log);
    339 #else
    340   fclose(log);
    341 #endif
    342 }
    343 
    344 void CloseLogFileUnlocked() {
    345   if (!log_file)
    346     return;
    347 
    348   CloseFile(log_file);
    349   log_file = NULL;
    350 }
    351 
    352 }  // namespace
    353 
    354 LoggingSettings::LoggingSettings()
    355     : logging_dest(LOG_DEFAULT),
    356       log_file(NULL),
    357       lock_log(LOCK_LOG_FILE),
    358       delete_old(APPEND_TO_OLD_LOG_FILE),
    359       dcheck_state(DISABLE_DCHECK_FOR_NON_OFFICIAL_RELEASE_BUILDS) {}
    360 
    361 bool BaseInitLoggingImpl(const LoggingSettings& settings) {
    362 #if defined(OS_NACL)
    363   // Can log only to the system debug log.
    364   CHECK_EQ(settings.logging_dest & ~LOG_TO_SYSTEM_DEBUG_LOG, 0);
    365 #endif
    366   g_dcheck_state = settings.dcheck_state;
    367   CommandLine* command_line = CommandLine::ForCurrentProcess();
    368   // Don't bother initializing g_vlog_info unless we use one of the
    369   // vlog switches.
    370   if (command_line->HasSwitch(switches::kV) ||
    371       command_line->HasSwitch(switches::kVModule)) {
    372     // NOTE: If g_vlog_info has already been initialized, it might be in use
    373     // by another thread. Don't delete the old VLogInfo, just create a second
    374     // one. We keep track of both to avoid memory leak warnings.
    375     CHECK(!g_vlog_info_prev);
    376     g_vlog_info_prev = g_vlog_info;
    377 
    378     g_vlog_info =
    379         new VlogInfo(command_line->GetSwitchValueASCII(switches::kV),
    380                      command_line->GetSwitchValueASCII(switches::kVModule),
    381                      &min_log_level);
    382   }
    383 
    384   logging_destination = settings.logging_dest;
    385 
    386   // ignore file options unless logging to file is set.
    387   if ((logging_destination & LOG_TO_FILE) == 0)
    388     return true;
    389 
    390   LoggingLock::Init(settings.lock_log, settings.log_file);
    391   LoggingLock logging_lock;
    392 
    393   // Calling InitLogging twice or after some log call has already opened the
    394   // default log file will re-initialize to the new options.
    395   CloseLogFileUnlocked();
    396 
    397   if (!log_file_name)
    398     log_file_name = new PathString();
    399   *log_file_name = settings.log_file;
    400   if (settings.delete_old == DELETE_OLD_LOG_FILE)
    401     DeleteFilePath(*log_file_name);
    402 
    403   return InitializeLogFileHandle();
    404 }
    405 
    406 void SetMinLogLevel(int level) {
    407   min_log_level = std::min(LOG_ERROR_REPORT, level);
    408 }
    409 
    410 int GetMinLogLevel() {
    411   return min_log_level;
    412 }
    413 
    414 int GetVlogVerbosity() {
    415   return std::max(-1, LOG_INFO - GetMinLogLevel());
    416 }
    417 
    418 int GetVlogLevelHelper(const char* file, size_t N) {
    419   DCHECK_GT(N, 0U);
    420   // Note: g_vlog_info may change on a different thread during startup
    421   // (but will always be valid or NULL).
    422   VlogInfo* vlog_info = g_vlog_info;
    423   return vlog_info ?
    424       vlog_info->GetVlogLevel(base::StringPiece(file, N - 1)) :
    425       GetVlogVerbosity();
    426 }
    427 
    428 void SetLogItems(bool enable_process_id, bool enable_thread_id,
    429                  bool enable_timestamp, bool enable_tickcount) {
    430   log_process_id = enable_process_id;
    431   log_thread_id = enable_thread_id;
    432   log_timestamp = enable_timestamp;
    433   log_tickcount = enable_tickcount;
    434 }
    435 
    436 void SetShowErrorDialogs(bool enable_dialogs) {
    437   show_error_dialogs = enable_dialogs;
    438 }
    439 
    440 void SetLogAssertHandler(LogAssertHandlerFunction handler) {
    441   log_assert_handler = handler;
    442 }
    443 
    444 void SetLogReportHandler(LogReportHandlerFunction handler) {
    445   log_report_handler = handler;
    446 }
    447 
    448 void SetLogMessageHandler(LogMessageHandlerFunction handler) {
    449   log_message_handler = handler;
    450 }
    451 
    452 LogMessageHandlerFunction GetLogMessageHandler() {
    453   return log_message_handler;
    454 }
    455 
    456 // MSVC doesn't like complex extern templates and DLLs.
    457 #if !defined(COMPILER_MSVC)
    458 // Explicit instantiations for commonly used comparisons.
    459 template std::string* MakeCheckOpString<int, int>(
    460     const int&, const int&, const char* names);
    461 template std::string* MakeCheckOpString<unsigned long, unsigned long>(
    462     const unsigned long&, const unsigned long&, const char* names);
    463 template std::string* MakeCheckOpString<unsigned long, unsigned int>(
    464     const unsigned long&, const unsigned int&, const char* names);
    465 template std::string* MakeCheckOpString<unsigned int, unsigned long>(
    466     const unsigned int&, const unsigned long&, const char* names);
    467 template std::string* MakeCheckOpString<std::string, std::string>(
    468     const std::string&, const std::string&, const char* name);
    469 #endif
    470 
    471 // Displays a message box to the user with the error message in it.
    472 // Used for fatal messages, where we close the app simultaneously.
    473 // This is for developers only; we don't use this in circumstances
    474 // (like release builds) where users could see it, since users don't
    475 // understand these messages anyway.
    476 void DisplayDebugMessageInDialog(const std::string& str) {
    477   if (str.empty())
    478     return;
    479 
    480   if (!show_error_dialogs)
    481     return;
    482 
    483 #if defined(OS_WIN)
    484   // For Windows programs, it's possible that the message loop is
    485   // messed up on a fatal error, and creating a MessageBox will cause
    486   // that message loop to be run. Instead, we try to spawn another
    487   // process that displays its command line. We look for "Debug
    488   // Message.exe" in the same directory as the application. If it
    489   // exists, we use it, otherwise, we use a regular message box.
    490   wchar_t prog_name[MAX_PATH];
    491   GetModuleFileNameW(NULL, prog_name, MAX_PATH);
    492   wchar_t* backslash = wcsrchr(prog_name, '\\');
    493   if (backslash)
    494     backslash[1] = 0;
    495   wcscat_s(prog_name, MAX_PATH, L"debug_message.exe");
    496 
    497   std::wstring cmdline = UTF8ToWide(str);
    498   if (cmdline.empty())
    499     return;
    500 
    501   STARTUPINFO startup_info;
    502   memset(&startup_info, 0, sizeof(startup_info));
    503   startup_info.cb = sizeof(startup_info);
    504 
    505   PROCESS_INFORMATION process_info;
    506   if (CreateProcessW(prog_name, &cmdline[0], NULL, NULL, false, 0, NULL,
    507                      NULL, &startup_info, &process_info)) {
    508     WaitForSingleObject(process_info.hProcess, INFINITE);
    509     CloseHandle(process_info.hThread);
    510     CloseHandle(process_info.hProcess);
    511   } else {
    512     // debug process broken, let's just do a message box
    513     MessageBoxW(NULL, &cmdline[0], L"Fatal error",
    514                 MB_OK | MB_ICONHAND | MB_TOPMOST);
    515   }
    516 #else
    517   // We intentionally don't implement a dialog on other platforms.
    518   // You can just look at stderr.
    519 #endif
    520 }
    521 
    522 #if defined(OS_WIN)
    523 LogMessage::SaveLastError::SaveLastError() : last_error_(::GetLastError()) {
    524 }
    525 
    526 LogMessage::SaveLastError::~SaveLastError() {
    527   ::SetLastError(last_error_);
    528 }
    529 #endif  // defined(OS_WIN)
    530 
    531 LogMessage::LogMessage(const char* file, int line, LogSeverity severity,
    532                        int ctr)
    533     : severity_(severity), file_(file), line_(line) {
    534   Init(file, line);
    535 }
    536 
    537 LogMessage::LogMessage(const char* file, int line)
    538     : severity_(LOG_INFO), file_(file), line_(line) {
    539   Init(file, line);
    540 }
    541 
    542 LogMessage::LogMessage(const char* file, int line, LogSeverity severity)
    543     : severity_(severity), file_(file), line_(line) {
    544   Init(file, line);
    545 }
    546 
    547 LogMessage::LogMessage(const char* file, int line, std::string* result)
    548     : severity_(LOG_FATAL), file_(file), line_(line) {
    549   Init(file, line);
    550   stream_ << "Check failed: " << *result;
    551   delete result;
    552 }
    553 
    554 LogMessage::LogMessage(const char* file, int line, LogSeverity severity,
    555                        std::string* result)
    556     : severity_(severity), file_(file), line_(line) {
    557   Init(file, line);
    558   stream_ << "Check failed: " << *result;
    559   delete result;
    560 }
    561 
    562 LogMessage::~LogMessage() {
    563 #if !defined(NDEBUG) && !defined(OS_NACL)
    564   if (severity_ == LOG_FATAL) {
    565     // Include a stack trace on a fatal.
    566     base::debug::StackTrace trace;
    567     stream_ << std::endl;  // Newline to separate from log message.
    568     trace.OutputToStream(&stream_);
    569   }
    570 #endif
    571   stream_ << std::endl;
    572   std::string str_newline(stream_.str());
    573 
    574   // Give any log message handler first dibs on the message.
    575   if (log_message_handler &&
    576       log_message_handler(severity_, file_, line_,
    577                           message_start_, str_newline)) {
    578     // The handler took care of it, no further processing.
    579     return;
    580   }
    581 
    582   if ((logging_destination & LOG_TO_SYSTEM_DEBUG_LOG) != 0) {
    583 #if defined(OS_WIN)
    584     OutputDebugStringA(str_newline.c_str());
    585 #elif defined(OS_ANDROID)
    586     android_LogPriority priority =
    587         (severity_ < 0) ? ANDROID_LOG_VERBOSE : ANDROID_LOG_UNKNOWN;
    588     switch (severity_) {
    589       case LOG_INFO:
    590         priority = ANDROID_LOG_INFO;
    591         break;
    592       case LOG_WARNING:
    593         priority = ANDROID_LOG_WARN;
    594         break;
    595       case LOG_ERROR:
    596       case LOG_ERROR_REPORT:
    597         priority = ANDROID_LOG_ERROR;
    598         break;
    599       case LOG_FATAL:
    600         priority = ANDROID_LOG_FATAL;
    601         break;
    602     }
    603     __android_log_write(priority, "chromium", str_newline.c_str());
    604 #endif
    605     fprintf(stderr, "%s", str_newline.c_str());
    606     fflush(stderr);
    607   } else if (severity_ >= kAlwaysPrintErrorLevel) {
    608     // When we're only outputting to a log file, above a certain log level, we
    609     // should still output to stderr so that we can better detect and diagnose
    610     // problems with unit tests, especially on the buildbots.
    611     fprintf(stderr, "%s", str_newline.c_str());
    612     fflush(stderr);
    613   }
    614 
    615   // write to log file
    616   if ((logging_destination & LOG_TO_FILE) != 0) {
    617     // We can have multiple threads and/or processes, so try to prevent them
    618     // from clobbering each other's writes.
    619     // If the client app did not call InitLogging, and the lock has not
    620     // been created do it now. We do this on demand, but if two threads try
    621     // to do this at the same time, there will be a race condition to create
    622     // the lock. This is why InitLogging should be called from the main
    623     // thread at the beginning of execution.
    624     LoggingLock::Init(LOCK_LOG_FILE, NULL);
    625     LoggingLock logging_lock;
    626     if (InitializeLogFileHandle()) {
    627 #if defined(OS_WIN)
    628       SetFilePointer(log_file, 0, 0, SEEK_END);
    629       DWORD num_written;
    630       WriteFile(log_file,
    631                 static_cast<const void*>(str_newline.c_str()),
    632                 static_cast<DWORD>(str_newline.length()),
    633                 &num_written,
    634                 NULL);
    635 #else
    636       fprintf(log_file, "%s", str_newline.c_str());
    637       fflush(log_file);
    638 #endif
    639     }
    640   }
    641 
    642   if (severity_ == LOG_FATAL) {
    643     // Ensure the first characters of the string are on the stack so they
    644     // are contained in minidumps for diagnostic purposes.
    645     char str_stack[1024];
    646     str_newline.copy(str_stack, arraysize(str_stack));
    647     base::debug::Alias(str_stack);
    648 
    649     // display a message or break into the debugger on a fatal error
    650     if (base::debug::BeingDebugged()) {
    651       base::debug::BreakDebugger();
    652     } else {
    653       if (log_assert_handler) {
    654         // make a copy of the string for the handler out of paranoia
    655         log_assert_handler(std::string(stream_.str()));
    656       } else {
    657         // Don't use the string with the newline, get a fresh version to send to
    658         // the debug message process. We also don't display assertions to the
    659         // user in release mode. The enduser can't do anything with this
    660         // information, and displaying message boxes when the application is
    661         // hosed can cause additional problems.
    662 #ifndef NDEBUG
    663         DisplayDebugMessageInDialog(stream_.str());
    664 #endif
    665         // Crash the process to generate a dump.
    666         base::debug::BreakDebugger();
    667       }
    668     }
    669   } else if (severity_ == LOG_ERROR_REPORT) {
    670     // We are here only if the user runs with --enable-dcheck in release mode.
    671     if (log_report_handler) {
    672       log_report_handler(std::string(stream_.str()));
    673     } else {
    674       DisplayDebugMessageInDialog(stream_.str());
    675     }
    676   }
    677 }
    678 
    679 // writes the common header info to the stream
    680 void LogMessage::Init(const char* file, int line) {
    681   base::StringPiece filename(file);
    682   size_t last_slash_pos = filename.find_last_of("\\/");
    683   if (last_slash_pos != base::StringPiece::npos)
    684     filename.remove_prefix(last_slash_pos + 1);
    685 
    686   // TODO(darin): It might be nice if the columns were fixed width.
    687 
    688   stream_ <<  '[';
    689   if (log_process_id)
    690     stream_ << CurrentProcessId() << ':';
    691   if (log_thread_id)
    692     stream_ << base::PlatformThread::CurrentId() << ':';
    693   if (log_timestamp) {
    694     time_t t = time(NULL);
    695     struct tm local_time = {0};
    696 #if _MSC_VER >= 1400
    697     localtime_s(&local_time, &t);
    698 #else
    699     localtime_r(&t, &local_time);
    700 #endif
    701     struct tm* tm_time = &local_time;
    702     stream_ << std::setfill('0')
    703             << std::setw(2) << 1 + tm_time->tm_mon
    704             << std::setw(2) << tm_time->tm_mday
    705             << '/'
    706             << std::setw(2) << tm_time->tm_hour
    707             << std::setw(2) << tm_time->tm_min
    708             << std::setw(2) << tm_time->tm_sec
    709             << ':';
    710   }
    711   if (log_tickcount)
    712     stream_ << TickCount() << ':';
    713   if (severity_ >= 0)
    714     stream_ << log_severity_names[severity_];
    715   else
    716     stream_ << "VERBOSE" << -severity_;
    717 
    718   stream_ << ":" << filename << "(" << line << ")] ";
    719 
    720   message_start_ = stream_.tellp();
    721 }
    722 
    723 #if defined(OS_WIN)
    724 // This has already been defined in the header, but defining it again as DWORD
    725 // ensures that the type used in the header is equivalent to DWORD. If not,
    726 // the redefinition is a compile error.
    727 typedef DWORD SystemErrorCode;
    728 #endif
    729 
    730 SystemErrorCode GetLastSystemErrorCode() {
    731 #if defined(OS_WIN)
    732   return ::GetLastError();
    733 #elif defined(OS_POSIX)
    734   return errno;
    735 #else
    736 #error Not implemented
    737 #endif
    738 }
    739 
    740 #if defined(OS_WIN)
    741 Win32ErrorLogMessage::Win32ErrorLogMessage(const char* file,
    742                                            int line,
    743                                            LogSeverity severity,
    744                                            SystemErrorCode err,
    745                                            const char* module)
    746     : err_(err),
    747       module_(module),
    748       log_message_(file, line, severity) {
    749 }
    750 
    751 Win32ErrorLogMessage::Win32ErrorLogMessage(const char* file,
    752                                            int line,
    753                                            LogSeverity severity,
    754                                            SystemErrorCode err)
    755     : err_(err),
    756       module_(NULL),
    757       log_message_(file, line, severity) {
    758 }
    759 
    760 Win32ErrorLogMessage::~Win32ErrorLogMessage() {
    761   const int error_message_buffer_size = 256;
    762   char msgbuf[error_message_buffer_size];
    763   DWORD flags = FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS;
    764   HMODULE hmod;
    765   if (module_) {
    766     hmod = GetModuleHandleA(module_);
    767     if (hmod) {
    768       flags |= FORMAT_MESSAGE_FROM_HMODULE;
    769     } else {
    770       // This makes a nested Win32ErrorLogMessage. It will have module_ of NULL
    771       // so it will not call GetModuleHandle, so recursive errors are
    772       // impossible.
    773       DPLOG(WARNING) << "Couldn't open module " << module_
    774           << " for error message query";
    775     }
    776   } else {
    777     hmod = NULL;
    778   }
    779   DWORD len = FormatMessageA(flags,
    780                              hmod,
    781                              err_,
    782                              0,
    783                              msgbuf,
    784                              sizeof(msgbuf) / sizeof(msgbuf[0]),
    785                              NULL);
    786   if (len) {
    787     while ((len > 0) &&
    788            isspace(static_cast<unsigned char>(msgbuf[len - 1]))) {
    789       msgbuf[--len] = 0;
    790     }
    791     stream() << ": " << msgbuf;
    792   } else {
    793     stream() << ": Error " << GetLastError() << " while retrieving error "
    794         << err_;
    795   }
    796   // We're about to crash (CHECK). Put |err_| on the stack (by placing it in a
    797   // field) and use Alias in hopes that it makes it into crash dumps.
    798   DWORD last_error = err_;
    799   base::debug::Alias(&last_error);
    800 }
    801 #elif defined(OS_POSIX)
    802 ErrnoLogMessage::ErrnoLogMessage(const char* file,
    803                                  int line,
    804                                  LogSeverity severity,
    805                                  SystemErrorCode err)
    806     : err_(err),
    807       log_message_(file, line, severity) {
    808 }
    809 
    810 ErrnoLogMessage::~ErrnoLogMessage() {
    811   stream() << ": " << safe_strerror(err_);
    812 }
    813 #endif  // OS_WIN
    814 
    815 void CloseLogFile() {
    816   LoggingLock logging_lock;
    817   CloseLogFileUnlocked();
    818 }
    819 
    820 void RawLog(int level, const char* message) {
    821   if (level >= min_log_level) {
    822     size_t bytes_written = 0;
    823     const size_t message_len = strlen(message);
    824     int rv;
    825     while (bytes_written < message_len) {
    826       rv = HANDLE_EINTR(
    827           write(STDERR_FILENO, message + bytes_written,
    828                 message_len - bytes_written));
    829       if (rv < 0) {
    830         // Give up, nothing we can do now.
    831         break;
    832       }
    833       bytes_written += rv;
    834     }
    835 
    836     if (message_len > 0 && message[message_len - 1] != '\n') {
    837       do {
    838         rv = HANDLE_EINTR(write(STDERR_FILENO, "\n", 1));
    839         if (rv < 0) {
    840           // Give up, nothing we can do now.
    841           break;
    842         }
    843       } while (rv != 1);
    844     }
    845   }
    846 
    847   if (level == LOG_FATAL)
    848     base::debug::BreakDebugger();
    849 }
    850 
    851 // This was defined at the beginning of this file.
    852 #undef write
    853 
    854 #if defined(OS_WIN)
    855 std::wstring GetLogFileFullPath() {
    856   if (log_file_name)
    857     return *log_file_name;
    858   return std::wstring();
    859 }
    860 #endif
    861 
    862 }  // namespace logging
    863 
    864 std::ostream& operator<<(std::ostream& out, const wchar_t* wstr) {
    865   return out << WideToUTF8(std::wstring(wstr));
    866 }
    867