logging.cc

// Copyright 2010-2021 Google LLC
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "ortools/base/logging.h"

#define _GNU_SOURCE 1  // needed for O_NOFOLLOW and pread()/pwrite()

#include <algorithm>
#include <cassert>
#include <iomanip>
#include <mutex>  // for std::call_once and std::once_flag.  // NOLINT
#include <string>

#if defined(_MSC_VER)
#include <io.h>     // lseek
#include <string.h> /* for _strnicmp(), strerror_s() */
#include <time.h>   /* for localtime_s() */
#include <windows.h>
#else
#include <pwd.h>
#include <sys/utsname.h>  // For uname.
#include <syslog.h>
#include <unistd.h>  // For _exit.
#endif
#include <errno.h>  // for errno
#include <fcntl.h>
#include <stdarg.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <climits>
#include <cstdio>
#include <iostream>
#include <sstream>
#include <vector>

#include "absl/debugging/stacktrace.h"
#include "absl/time/time.h"
#include "ortools/base/commandlineflags.h"
#include "ortools/base/logging_utilities.h"
#include "ortools/base/raw_logging.h"

ABSL_DECLARE_FLAG(bool, log_prefix);
ABSL_DECLARE_FLAG(bool, logtostderr);

namespace {
std::once_flag init_done;
}  // namespace

void FixFlagsAndEnvironmentForSwig() {
  std::call_once(init_done, [] { google::InitGoogleLogging("swig_helper"); });
  absl::SetFlag(&FLAGS_logtostderr, true);
  absl::SetFlag(&FLAGS_log_prefix, false);
}

using std::dec;
using std::hex;
using std::min;
using std::ostream;
using std::ostringstream;
using std::setfill;
using std::setw;
using std::string;
using std::vector;

using std::fclose;
using std::fflush;
using std::FILE;
using std::fprintf;
using std::fwrite;
using std::perror;

#ifdef _WIN32
#define fdopen _fdopen
#define strcasecmp _stricmp
#endif

#if defined(_MSC_VER)
#ifndef __MINGW32__
enum { STDIN_FILENO = 0, STDOUT_FILENO = 1, STDERR_FILENO = 2 };
#endif

inline char* strerror_r(int errnum, char* buf, size_t buflen) {
  strerror_s(buf, buflen, errnum);
  return buf;
}

inline struct tm* localtime_r(const time_t* timep, struct tm* result) {
  localtime_s(result, timep);
  return result;
}
#endif

ABSL_FLAG(bool, logtostderr, false,
          "log messages go to stderr instead of logfiles");
ABSL_FLAG(bool, alsologtostderr, false,
          "log messages go to stderr in addition to logfiles");
ABSL_FLAG(bool, colorlogtostderr, false,
          "color messages logged to stderr (if supported by terminal)");
#if defined(__linux__)
ABSL_FLAG(bool, drop_log_memory, true,
          "Drop in-memory buffers of log contents. "
          "Logs can grow very quickly and they are rarely read before they "
          "need to be evicted from memory. Instead, drop them from memory "
          "as soon as they are flushed to disk.");
#endif

// By default, errors (including fatal errors) get logged to stderr as
// well as the file.
//
// The default is ERROR instead of FATAL so that users can see problems
// when they run a program without having to look in another file.
ABSL_FLAG(int, stderrthreshold, google::GLOG_ERROR,
          "log messages at or above this level are copied to stderr in "
          "addition to logfiles.  This flag obsoletes --alsologtostderr.");

ABSL_FLAG(bool, log_prefix, true,
          "Prepend the log prefix to the start of each log line");
ABSL_FLAG(int, minloglevel, 0,
          "Messages logged at a lower level than this don't "
          "actually get logged anywhere");
ABSL_FLAG(int, logbuflevel, 0,
          "Buffer log messages logged at this level or lower"
          " (-1 means don't buffer; 0 means buffer INFO only;"
          " ...)");
ABSL_FLAG(int, logbufsecs, 30,
          "Buffer log messages for at most this many seconds");

// Compute the default value for --log_dir
static const char* DefaultLogDir() {
  const char* env;
  env = getenv("GOOGLE_LOG_DIR");
  if (env != NULL && env[0] != '\0') {
    return env;
  }
  env = getenv("TEST_TMPDIR");
  if (env != NULL && env[0] != '\0') {
    return env;
  }
  return "";
}

ABSL_FLAG(int, logfile_mode, 0664, "Log file mode/permissions.");

ABSL_FLAG(std::string, log_dir, DefaultLogDir(),
          "If specified, logfiles are written into this directory instead "
          "of the default logging directory.");
ABSL_FLAG(std::string, log_link, "",
          "Put additional links to the log "
          "files in this directory");

ABSL_FLAG(int, max_log_size, 1800,
          "approx. maximum log file size (in MB). A value of 0 will "
          "be silently overridden to 1.");

ABSL_FLAG(bool, stop_logging_if_full_disk, false,
          "Stop attempting to log to disk if the disk is full.");

ABSL_FLAG(std::string, log_backtrace_at, "",
          "Emit a backtrace when logging at file:linenum.");

#if defined(_MSC_VER)
#define PATH_SEPARATOR '\\'
#else
#define PATH_SEPARATOR '/'
#endif

#ifdef _MSC_VER
#include <basetsd.h>
#define ssize_t SSIZE_T
static ssize_t pread(int fd, void* buf, size_t count, off_t offset) {
  off_t orig_offset = lseek(fd, 0, SEEK_CUR);
  if (orig_offset == (off_t)-1) return -1;
  if (lseek(fd, offset, SEEK_CUR) == (off_t)-1) return -1;
  ssize_t len = read(fd, buf, count);
  if (len < 0) return len;
  if (lseek(fd, orig_offset, SEEK_SET) == (off_t)-1) return -1;
  return len;
}

static ssize_t pwrite(int fd, void* buf, size_t count, off_t offset) {
  off_t orig_offset = lseek(fd, 0, SEEK_CUR);
  if (orig_offset == (off_t)-1) return -1;
  if (lseek(fd, offset, SEEK_CUR) == (off_t)-1) return -1;
  ssize_t len = write(fd, buf, count);
  if (len < 0) return len;
  if (lseek(fd, orig_offset, SEEK_SET) == (off_t)-1) return -1;
  return len;
}
#endif  // _MSC_VER

static void GetHostName(string* hostname) {
#if !defined(_MSC_VER)
  struct utsname buf;
  if (0 != uname(&buf)) {
    // ensure null termination on failure
    *buf.nodename = '\0';
  }
  *hostname = buf.nodename;
#else   // _MSC_VER
  char buf[MAX_COMPUTERNAME_LENGTH + 1];
  DWORD len = MAX_COMPUTERNAME_LENGTH + 1;
  if (GetComputerNameA(buf, &len)) {
    *hostname = buf;
  } else {
    hostname->clear();
  }
#endif  // _MSC_VER
}

// Returns true iff terminal supports using colors in output.
static bool TerminalSupportsColor() {
  bool term_supports_color = false;
#ifdef _MSC_VER
  // on Windows TERM variable is usually not set, but the console does
  // support colors.
  term_supports_color = true;
#else
  // On non-Windows platforms, we rely on the TERM variable.
  const char* const term = getenv("TERM");
  if (term != NULL && term[0] != '\0') {
    term_supports_color =
        !strcmp(term, "xterm") || !strcmp(term, "xterm-color") ||
        !strcmp(term, "xterm-256color") || !strcmp(term, "screen-256color") ||
        !strcmp(term, "konsole") || !strcmp(term, "konsole-16color") ||
        !strcmp(term, "konsole-256color") || !strcmp(term, "screen") ||
        !strcmp(term, "linux") || !strcmp(term, "cygwin");
  }
#endif
  return term_supports_color;
}

namespace google {

enum GLogColor { COLOR_DEFAULT, COLOR_RED, COLOR_GREEN, COLOR_YELLOW };

static GLogColor SeverityToColor(LogSeverity severity) {
  assert(severity >= 0 && severity < NUM_SEVERITIES);
  GLogColor color = COLOR_DEFAULT;
  switch (severity) {
    case GLOG_INFO:
      color = COLOR_DEFAULT;
      break;
    case GLOG_WARNING:
      color = COLOR_YELLOW;
      break;
    case GLOG_ERROR:
    case GLOG_FATAL:
      color = COLOR_RED;
      break;
    default:
      // should never get here.
      assert(false);
  }
  return color;
}

#ifdef _MSC_VER

// Returns the character attribute for the given color.
static WORD GetColorAttribute(GLogColor color) {
  switch (color) {
    case COLOR_RED:
      return FOREGROUND_RED;
    case COLOR_GREEN:
      return FOREGROUND_GREEN;
    case COLOR_YELLOW:
      return FOREGROUND_RED | FOREGROUND_GREEN;
    default:
      return 0;
  }
}

#else  // _MSC_VER

// Returns the ANSI color code for the given color.
static const char* GetAnsiColorCode(GLogColor color) {
  switch (color) {
    case COLOR_RED:
      return "1";
    case COLOR_GREEN:
      return "2";
    case COLOR_YELLOW:
      return "3";
    case COLOR_DEFAULT:
      return "";
  }
  return NULL;  // stop warning about return type.
}

#endif  // !_MSC_VER

// Safely get max_log_size, overriding to 1 if it somehow gets defined as 0
static int32_t MaxLogSize() {
  return (absl::GetFlag(FLAGS_max_log_size) > 0
              ? absl::GetFlag(FLAGS_max_log_size)
              : 1);
}

// An arbitrary limit on the length of a single log message.  This
// is so that streaming can be done more efficiently.
const size_t LogMessage::kMaxLogMessageLen = 30000;

struct LogMessage::LogMessageData {
  LogMessageData();

  int preserved_errno_;  // preserved errno
  // Buffer space; contains complete message text.
  char message_text_[LogMessage::kMaxLogMessageLen + 1];
  LogStream stream_;
  char severity_;  // What level is this LogMessage logged at?
  int line_;       // line number where logging call is.
  void (LogMessage::*send_method_)();  // Call this in destructor to send
  union {  // At most one of these is used: union to keep the size low.
    LogSink* sink_;                     // NULL or sink to send message to
    std::vector<std::string>* outvec_;  // NULL or vector to push message onto
    std::string* message_;              // NULL or string to write message into
  };
  time_t timestamp_;            // Time of creation of LogMessage
  struct ::tm tm_time_;         // Time of creation of LogMessage
  size_t num_prefix_chars_;     // # of chars of prefix in this message
  size_t num_chars_to_log_;     // # of chars of msg to send to log
  size_t num_chars_to_syslog_;  // # of chars of msg to send to syslog
  const char* basename_;        // basename of file that called LOG
  const char* fullname_;        // fullname of file that called LOG
  bool has_been_flushed_;       // false => data has not been flushed
  bool first_fatal_;            // true => this was first fatal msg

 private:
  LogMessageData(const LogMessageData&);
  void operator=(const LogMessageData&);
};

// A absl::Mutex that allows only one thread to log at a time, to keep things
// from getting jumbled.  Some other very uncommon logging operations (like
// changing the destination file for log messages of a given severity) also
// lock this absl::Mutex.  Please be sure that anybody who might possibly need
// to lock it does so.
static absl::Mutex log_mutex;

// Number of messages sent at each severity.  Under log_mutex.
int64_t LogMessage::num_messages_[NUM_SEVERITIES] = {0, 0, 0, 0};

// Globally disable log writing (if disk is full)
static bool stop_writing = false;

const char* const LogSeverityNames[NUM_SEVERITIES] = {"INFO", "WARNING",
                                                      "ERROR", "FATAL"};

// Has the user called SetExitOnDFatal(true)?
static bool exit_on_dfatal = true;

const char* GetLogSeverityName(LogSeverity severity) {
  return LogSeverityNames[severity];
}

base::Logger::~Logger() {}

namespace {

// Encapsulates all file-system related state
class LogFileObject : public base::Logger {
 public:
  LogFileObject(LogSeverity severity, const char* base_filename);
  ~LogFileObject();

  virtual void Write(bool force_flush,  // Should we force a flush here?
                     time_t timestamp,  // Timestamp for this entry
                     const char* message, int message_len);

  // Configuration options
  void SetBasename(const char* basename);
  void SetExtension(const char* ext);
  void SetSymlinkBasename(const char* symlink_basename);

  // Normal flushing routine
  virtual void Flush();

  // It is the actual file length for the system loggers,
  // i.e., INFO, ERROR, etc.
  virtual uint32_t LogSize() {
    absl::MutexLock l(&lock_);
    return file_length_;
  }

  // Internal flush routine.  Exposed so that FlushLogFilesUnsafe()
  // can avoid grabbing a lock.  Usually Flush() calls it after
  // acquiring lock_.
  void FlushUnlocked();

 private:
  static const uint32_t kRolloverAttemptFrequency = 0x20;

  absl::Mutex lock_;
  bool base_filename_selected_;
  string base_filename_;
  string symlink_basename_;
  string filename_extension_;  // option users can specify (eg to add port#)
  FILE* file_;
  LogSeverity severity_;
  uint32_t bytes_since_flush_;
  uint32_t dropped_mem_length_;
  uint32_t file_length_;
  unsigned int rollover_attempt_;
  int64_t next_flush_time_;  // cycle count at which to flush log

  // Actually create a logfile using the value of base_filename_ and the
  // supplied argument time_pid_string
  // REQUIRES: lock_ is held
  bool CreateLogfile(const string& time_pid_string);
};

}  // namespace

class LogDestination {
 public:
  friend class LogMessage;
  friend void ReprintFatalMessage();
  friend base::Logger* base::GetLogger(LogSeverity);
  friend void base::SetLogger(LogSeverity, base::Logger*);

  // These methods are just forwarded to by their global versions.
  static void SetLogDestination(LogSeverity severity,
                                const char* base_filename);
  static void SetLogSymlink(LogSeverity severity, const char* symlink_basename);
  static void AddLogSink(LogSink* destination);
  static void RemoveLogSink(LogSink* destination);
  static void SetLogFilenameExtension(const char* filename_extension);
  static void SetStderrLogging(LogSeverity min_severity);
  static void LogToStderr();
  // Flush all log files that are at least at the given severity level
  static void FlushLogFiles(int min_severity);
  static void FlushLogFilesUnsafe(int min_severity);

  // we set the maximum size of our packet to be 1400, the logic being
  // to prevent fragmentation.
  // Really this number is arbitrary.
  static const int kNetworkBytes = 1400;

  static const string& hostname();
  static const bool& terminal_supports_color() {
    return terminal_supports_color_;
  }

  static void DeleteLogDestinations();

 private:
  LogDestination(LogSeverity severity, const char* base_filename);
  ~LogDestination() {}

  // Take a log message of a particular severity and log it to stderr
  // iff it's of a high enough severity to deserve it.
  static void MaybeLogToStderr(LogSeverity severity, const char* message,
                               size_t len);

  // Take a log message of a particular severity and log it to a file
  // iff the base filename is not "" (which means "don't log to me")
  static void MaybeLogToLogfile(LogSeverity severity, time_t timestamp,
                                const char* message, size_t len);
  // Take a log message of a particular severity and log it to the file
  // for that severity and also for all files with severity less than
  // this severity.
  static void LogToAllLogfiles(LogSeverity severity, time_t timestamp,
                               const char* message, size_t len);

  // Send logging info to all registered sinks.
  static void LogToSinks(LogSeverity severity, const char* full_filename,
                         const char* base_filename, int line,
                         const struct ::tm* tm_time, const char* message,
                         size_t message_len);

  // Wait for all registered sinks via WaitTillSent
  // including the optional one in "data".
  static void WaitForSinks(LogMessage::LogMessageData* data);

  static LogDestination* log_destination(LogSeverity severity);

  LogFileObject fileobject_;
  base::Logger* logger_;  // Either &fileobject_, or wrapper around it

  static LogDestination* log_destinations_[NUM_SEVERITIES];
  static string addresses_;
  static string hostname_;
  static bool terminal_supports_color_;

  // arbitrary global logging destinations.
  static vector<LogSink*>* sinks_;

  // Protects the vector sinks_,
  // but not the LogSink objects its elements reference.
  static absl::Mutex sink_mutex_;

  // Disallow
  LogDestination(const LogDestination&);
  LogDestination& operator=(const LogDestination&);
};

string LogDestination::addresses_;  // NOLINT
string LogDestination::hostname_;   // NOLINT

vector<LogSink*>* LogDestination::sinks_ = NULL;
absl::Mutex LogDestination::sink_mutex_;
bool LogDestination::terminal_supports_color_ = TerminalSupportsColor();

/* static */
const string& LogDestination::hostname() {
  if (hostname_.empty()) {
    GetHostName(&hostname_);
    if (hostname_.empty()) {
      hostname_ = "(unknown)";
    }
  }
  return hostname_;
}

LogDestination::LogDestination(LogSeverity severity, const char* base_filename)
    : fileobject_(severity, base_filename), logger_(&fileobject_) {}

inline void LogDestination::FlushLogFilesUnsafe(int min_severity) {
  // assume we have the log_mutex or we simply don't care
  // about it
  for (int i = min_severity; i < NUM_SEVERITIES; i++) {
    LogDestination* log = log_destinations_[i];
    if (log != NULL) {
      // Flush the base fileobject_ logger directly instead of going
      // through any wrappers to reduce chance of deadlock.
      log->fileobject_.FlushUnlocked();
    }
  }
}

inline void LogDestination::FlushLogFiles(int min_severity) {
  // Prevent any subtle race conditions by wrapping a absl::Mutex lock around
  // all this stuff.
  absl::MutexLock l(&log_mutex);
  for (int i = min_severity; i < NUM_SEVERITIES; i++) {
    LogDestination* log = log_destination(i);
    if (log != NULL) {
      log->logger_->Flush();
    }
  }
}

inline void LogDestination::SetLogDestination(LogSeverity severity,
                                              const char* base_filename) {
  assert(severity >= 0 && severity < NUM_SEVERITIES);
  // Prevent any subtle race conditions by wrapping a absl::Mutex lock around
  // all this stuff.
  absl::MutexLock l(&log_mutex);
  log_destination(severity)->fileobject_.SetBasename(base_filename);
}

inline void LogDestination::SetLogSymlink(LogSeverity severity,
                                          const char* symlink_basename) {
  CHECK_GE(severity, 0);
  CHECK_LT(severity, NUM_SEVERITIES);
  absl::MutexLock l(&log_mutex);
  log_destination(severity)->fileobject_.SetSymlinkBasename(symlink_basename);
}

inline void LogDestination::AddLogSink(LogSink* destination) {
  // Prevent any subtle race conditions by wrapping a absl::Mutex lock around
  // all this stuff.
  absl::MutexLock l(&sink_mutex_);
  if (!sinks_) sinks_ = new vector<LogSink*>;
  sinks_->push_back(destination);
}

inline void LogDestination::RemoveLogSink(LogSink* destination) {
  // Prevent any subtle race conditions by wrapping a absl::Mutex lock around
  // all this stuff.
  absl::MutexLock l(&sink_mutex_);
  // This doesn't keep the sinks in order, but who cares?
  if (sinks_) {
    for (int i = sinks_->size() - 1; i >= 0; i--) {
      if ((*sinks_)[i] == destination) {
        (*sinks_)[i] = (*sinks_)[sinks_->size() - 1];
        sinks_->pop_back();
        break;
      }
    }
  }
}

inline void LogDestination::SetLogFilenameExtension(const char* ext) {
  // Prevent any subtle race conditions by wrapping a absl::Mutex lock around
  // all this stuff.
  absl::MutexLock l(&log_mutex);
  for (int severity = 0; severity < NUM_SEVERITIES; ++severity) {
    log_destination(severity)->fileobject_.SetExtension(ext);
  }
}

inline void LogDestination::SetStderrLogging(LogSeverity min_severity) {
  assert(min_severity >= 0 && min_severity < NUM_SEVERITIES);
  // Prevent any subtle race conditions by wrapping a absl::Mutex lock around
  // all this stuff.
  absl::MutexLock l(&log_mutex);
  absl::SetFlag(&FLAGS_stderrthreshold, min_severity);
}

inline void LogDestination::LogToStderr() {
  // *Don't* put this stuff in a absl::Mutex lock, since SetStderrLogging &
  // SetLogDestination already do the locking!
  SetStderrLogging(0);  // thus everything is "also" logged to stderr
  for (int i = 0; i < NUM_SEVERITIES; ++i) {
    SetLogDestination(i, "");  // "" turns off logging to a logfile
  }
}

static void ColoredWriteToStderr(LogSeverity severity, const char* message,
                                 size_t len) {
  const GLogColor color = (LogDestination::terminal_supports_color() &&
                           absl::GetFlag(FLAGS_colorlogtostderr))
                              ? SeverityToColor(severity)
                              : COLOR_DEFAULT;

  // Avoid using cerr from this module since we may get called during
  // exit code, and cerr may be partially or fully destroyed by then.
  if (COLOR_DEFAULT == color) {
    fwrite(message, len, 1, stderr);
    return;
  }
#ifdef _MSC_VER
  const HANDLE stderr_handle = GetStdHandle(STD_ERROR_HANDLE);

  // Gets the current text color.
  CONSOLE_SCREEN_BUFFER_INFO buffer_info;
  GetConsoleScreenBufferInfo(stderr_handle, &buffer_info);
  const WORD old_color_attrs = buffer_info.wAttributes;

  // We need to flush the stream buffers into the console before each
  // SetConsoleTextAttribute call lest it affect the text that is already
  // printed but has not yet reached the console.
  fflush(stderr);
  SetConsoleTextAttribute(stderr_handle,
                          GetColorAttribute(color) | FOREGROUND_INTENSITY);
  fwrite(message, len, 1, stderr);
  fflush(stderr);
  // Restores the text color.
  SetConsoleTextAttribute(stderr_handle, old_color_attrs);
#else   // !_MSC_VER
  fprintf(stderr, "\033[0;3%sm", GetAnsiColorCode(color));
  fwrite(message, len, 1, stderr);
  fprintf(stderr, "\033[m");  // Resets the terminal to default.
#endif  // !_MSC_VER
}

static void WriteToStderr(const char* message, size_t len) {
  // Avoid using cerr from this module since we may get called during
  // exit code, and cerr may be partially or fully destroyed by then.
  fwrite(message, len, 1, stderr);
}

inline void LogDestination::MaybeLogToStderr(LogSeverity severity,
                                             const char* message, size_t len) {
  if ((severity >= absl::GetFlag(FLAGS_stderrthreshold)) ||
      absl::GetFlag(FLAGS_alsologtostderr)) {
    ColoredWriteToStderr(severity, message, len);
#ifdef _MSC_VER
    // On Windows, also output to the debugger
    ::OutputDebugStringA(string(message, len).c_str());
#endif
  }
}

inline void LogDestination::MaybeLogToLogfile(LogSeverity severity,
                                              time_t timestamp,
                                              const char* message, size_t len) {
  const bool should_flush = severity > absl::GetFlag(FLAGS_logbuflevel);
  LogDestination* destination = log_destination(severity);
  destination->logger_->Write(should_flush, timestamp, message, len);
}

inline void LogDestination::LogToAllLogfiles(LogSeverity severity,
                                             time_t timestamp,
                                             const char* message, size_t len) {
  if (absl::GetFlag(FLAGS_logtostderr)) {  // global flag: never log to file
    ColoredWriteToStderr(severity, message, len);
  } else {
    for (int i = severity; i >= 0; --i)
      LogDestination::MaybeLogToLogfile(i, timestamp, message, len);
  }
}

inline void LogDestination::LogToSinks(LogSeverity severity,
                                       const char* full_filename,
                                       const char* base_filename, int line,
                                       const struct ::tm* tm_time,
                                       const char* message,
                                       size_t message_len) {
  absl::ReaderMutexLock l(&sink_mutex_);
  if (sinks_) {
    for (int i = sinks_->size() - 1; i >= 0; i--) {
      (*sinks_)[i]->send(severity, full_filename, base_filename, line, tm_time,
                         message, message_len);
    }
  }
}

inline void LogDestination::WaitForSinks(LogMessage::LogMessageData* data) {
  absl::ReaderMutexLock l(&sink_mutex_);
  if (sinks_) {
    for (int i = sinks_->size() - 1; i >= 0; i--) {
      (*sinks_)[i]->WaitTillSent();
    }
  }
  const bool send_to_sink =
      (data->send_method_ == &LogMessage::SendToSink) ||
      (data->send_method_ == &LogMessage::SendToSinkAndLog);
  if (send_to_sink && data->sink_ != NULL) {
    data->sink_->WaitTillSent();
  }
}

LogDestination* LogDestination::log_destinations_[NUM_SEVERITIES];

inline LogDestination* LogDestination::log_destination(LogSeverity severity) {
  assert(severity >= 0 && severity < NUM_SEVERITIES);
  if (!log_destinations_[severity]) {
    log_destinations_[severity] = new LogDestination(severity, NULL);
  }
  return log_destinations_[severity];
}

void LogDestination::DeleteLogDestinations() {
  for (int severity = 0; severity < NUM_SEVERITIES; ++severity) {
    delete log_destinations_[severity];
    log_destinations_[severity] = NULL;
  }
  absl::MutexLock l(&sink_mutex_);
  delete sinks_;
  sinks_ = NULL;
}

namespace {

LogFileObject::LogFileObject(LogSeverity severity, const char* base_filename)
    : base_filename_selected_(base_filename != NULL),
      base_filename_((base_filename != NULL) ? base_filename : ""),
      symlink_basename_(logging_internal::ProgramInvocationShortName()),
      filename_extension_(),
      file_(NULL),
      severity_(severity),
      bytes_since_flush_(0),
      dropped_mem_length_(0),
      file_length_(0),
      rollover_attempt_(kRolloverAttemptFrequency - 1),
      next_flush_time_(0) {
  assert(severity >= 0);
  assert(severity < NUM_SEVERITIES);
}

LogFileObject::~LogFileObject() {
  absl::MutexLock l(&lock_);
  if (file_ != NULL) {
    fclose(file_);
    file_ = NULL;
  }
}

void LogFileObject::SetBasename(const char* basename) {
  absl::MutexLock l(&lock_);
  base_filename_selected_ = true;
  if (base_filename_ != basename) {
    // Get rid of old log file since we are changing names
    if (file_ != NULL) {
      fclose(file_);
      file_ = NULL;
      rollover_attempt_ = kRolloverAttemptFrequency - 1;
    }
    base_filename_ = basename;
  }
}

void LogFileObject::SetExtension(const char* ext) {
  absl::MutexLock l(&lock_);
  if (filename_extension_ != ext) {
    // Get rid of old log file since we are changing names
    if (file_ != NULL) {
      fclose(file_);
      file_ = NULL;
      rollover_attempt_ = kRolloverAttemptFrequency - 1;
    }
    filename_extension_ = ext;
  }
}

void LogFileObject::SetSymlinkBasename(const char* symlink_basename) {
  absl::MutexLock l(&lock_);
  symlink_basename_ = symlink_basename;
}

void LogFileObject::Flush() {
  absl::MutexLock l(&lock_);
  FlushUnlocked();
}

void LogFileObject::FlushUnlocked() {
  if (file_ != NULL) {
    fflush(file_);
    bytes_since_flush_ = 0;
  }
  // Figure out when we are due for another flush.
  const int64_t next = (absl::GetFlag(FLAGS_logbufsecs) *
                        static_cast<int64_t>(1000000));  // in usec
  next_flush_time_ =
      logging_internal::CycleClock_Now() + logging_internal::UsecToCycles(next);
}

bool LogFileObject::CreateLogfile(const string& time_pid_string) {
  string string_filename =
      base_filename_ + filename_extension_ + time_pid_string;
  const char* filename = string_filename.c_str();
  int fd = open(filename, O_WRONLY | O_CREAT | O_EXCL,
                absl::GetFlag(FLAGS_logfile_mode));
  if (fd == -1) return false;
#if !defined(_MSC_VER)
  // Mark the file close-on-exec. We don't really care if this fails
  fcntl(fd, F_SETFD, FD_CLOEXEC);
#endif

  file_ = fdopen(fd, "a");  // Make a FILE*.
  if (file_ == NULL) {      // Man, we're screwed!
    close(fd);
    unlink(filename);  // Erase the half-baked evidence: an unusable log file
    return false;
  }

  // We try to create a symlink called <program_name>.<severity>,
  // which is easier to use.  (Every time we create a new logfile,
  // we destroy the old symlink and create a new one, so it always
  // points to the latest logfile.)  If it fails, we're sad but it's
  // no error.
  if (!symlink_basename_.empty()) {
    // take directory from filename
    const char* slash = strrchr(filename, PATH_SEPARATOR);
    const string linkname =
        symlink_basename_ + '.' + LogSeverityNames[severity_];
    string linkpath;
    if (slash)
      linkpath = string(filename, slash - filename + 1);  // get dirname
    linkpath += linkname;
    unlink(linkpath.c_str());  // delete old one if it exists

#if !defined(_MSC_VER)
    // We must have unistd.h.
    // Make the symlink be relative (in the same dir) so that if the
    // entire log directory gets relocated the link is still valid.
    const char* linkdest = slash ? (slash + 1) : filename;
    if (symlink(linkdest, linkpath.c_str()) != 0) {
      // silently ignore failures
    }

    // Make an additional link to the log file in a place specified by
    // absl::GetFlag(FLAGS_log_link), if indicated
    if (!absl::GetFlag(FLAGS_log_link).empty()) {
      linkpath = absl::GetFlag(FLAGS_log_link) + "/" + linkname;
      unlink(linkpath.c_str());  // delete old one if it exists
      if (symlink(filename, linkpath.c_str()) != 0) {
        // silently ignore failures
      }
    }
#endif  // !_MSC_VER
  }

  return true;  // Everything worked
}

void LogFileObject::Write(bool force_flush, time_t timestamp,
                          const char* message, int message_len) {
  absl::MutexLock l(&lock_);

  // We don't log if the base_name_ is "" (which means "don't write")
  if (base_filename_selected_ && base_filename_.empty()) {
    return;
  }

  if (static_cast<int>(file_length_ >> 20) >= MaxLogSize()) {
    if (file_ != NULL) fclose(file_);
    file_ = NULL;
    file_length_ = bytes_since_flush_ = dropped_mem_length_ = 0;
    rollover_attempt_ = kRolloverAttemptFrequency - 1;
  }

  // If there's no destination file, make one before outputting
  if (file_ == NULL) {
    // Try to rollover the log file every 32 log messages.  The only time
    // this could matter would be when we have trouble creating the log
    // file.  If that happens, we'll lose lots of log messages, of course!
    if (++rollover_attempt_ != kRolloverAttemptFrequency) return;
    rollover_attempt_ = 0;

    struct ::tm tm_time;
    localtime_r(&timestamp, &tm_time);

    // The logfile's filename will have the date/time & pid in it
    ostringstream time_pid_stream;
    time_pid_stream.fill('0');
    time_pid_stream << 1900 + tm_time.tm_year << setw(2) << 1 + tm_time.tm_mon
                    << setw(2) << tm_time.tm_mday << '-' << setw(2)
                    << tm_time.tm_hour << setw(2) << tm_time.tm_min << setw(2)
                    << tm_time.tm_sec << '.'
                    << logging_internal::GetMainThreadPid();
    const string& time_pid_string = time_pid_stream.str();

    if (base_filename_selected_) {
      if (!CreateLogfile(time_pid_string)) {
        perror("Could not create log file");
        fprintf(stderr, "COULD NOT CREATE LOGFILE '%s'!\n",
                time_pid_string.c_str());
        return;
      }
    } else {
      // If no base filename for logs of this severity has been set, use a
      // default base filename of
      // "<program name>.<hostname>.<user name>.log.<severity level>.".  So
      // logfiles will have names like
      // webserver.examplehost.root.log.INFO.19990817-150000.4354, where
      // 19990817 is a date (1999 August 17), 150000 is a time (15:00:00),
      // and 4354 is the pid of the logging process.  The date & time reflect
      // when the file was created for output.
      //
      // Where does the file get put?  Successively try the directories
      // "/tmp", and "."
      string stripped_filename(logging_internal::ProgramInvocationShortName());
      string hostname;
      GetHostName(&hostname);

      string uidname = logging_internal::MyUserName();
      // We should not call CHECK() here because this function can be
      // called after holding on to log_mutex. We don't want to
      // attempt to hold on to the same absl::Mutex, and get into a
      // deadlock. Simply use a name like invalid-user.
      if (uidname.empty()) uidname = "invalid-user";

      stripped_filename = stripped_filename + '.' + hostname + '.' + uidname +
                          ".log." + LogSeverityNames[severity_] + '.';
      // We're going to (potentially) try to put logs in several different dirs
      const vector<string>& log_dirs = GetLoggingDirectories();

      // Go through the list of dirs, and try to create the log file in each
      // until we succeed or run out of options
      bool success = false;
      for (vector<string>::const_iterator dir = log_dirs.begin();
           dir != log_dirs.end(); ++dir) {
        base_filename_ = *dir + "/" + stripped_filename;
        if (CreateLogfile(time_pid_string)) {
          success = true;
          break;
        }
      }
      // If we never succeeded, we have to give up
      if (success == false) {
        perror("Could not create logging file");
        fprintf(stderr, "COULD NOT CREATE A LOGGINGFILE %s!",
                time_pid_string.c_str());
        return;
      }
    }

    // Write a header message into the log file
    ostringstream file_header_stream;
    file_header_stream.fill('0');
    file_header_stream << "Log file created at: " << 1900 + tm_time.tm_year
                       << '/' << setw(2) << 1 + tm_time.tm_mon << '/' << setw(2)
                       << tm_time.tm_mday << ' ' << setw(2) << tm_time.tm_hour
                       << ':' << setw(2) << tm_time.tm_min << ':' << setw(2)
                       << tm_time.tm_sec << '\n'
                       << "Running on machine: " << LogDestination::hostname()
                       << '\n'
                       << "Log line format: [IWEF]mmdd hh:mm:ss.uuuuuu "
                       << "threadid file:line] msg" << '\n';
    const string& file_header_string = file_header_stream.str();

    const int header_len = file_header_string.size();
    fwrite(file_header_string.data(), 1, header_len, file_);
    file_length_ += header_len;
    bytes_since_flush_ += header_len;
  }

  // Write to LOG file
  if (!stop_writing) {
    // fwrite() doesn't return an error when the disk is full, for
    // messages that are less than 4096 bytes. When the disk is full,
    // it returns the message length for messages that are less than
    // 4096 bytes. fwrite() returns 4096 for message lengths that are
    // greater than 4096, thereby indicating an error.
    errno = 0;
    fwrite(message, 1, message_len, file_);
    if (absl::GetFlag(FLAGS_stop_logging_if_full_disk) &&
        errno == ENOSPC) {  // disk full, stop writing to disk
      stop_writing = true;  // until the disk is
      return;
    } else {
      file_length_ += message_len;
      bytes_since_flush_ += message_len;
    }
  } else {
    if (logging_internal::CycleClock_Now() >= next_flush_time_)
      stop_writing = false;  // check to see if disk has free space.
    return;                  // no need to flush
  }

  // See important msgs *now*.  Also, flush logs at least every 10^6 chars,
  // or every "absl::GetFlag(FLAGS_logbufsecs)" seconds.
  if (force_flush || (bytes_since_flush_ >= 1000000) ||
      (logging_internal::CycleClock_Now() >= next_flush_time_)) {
    FlushUnlocked();
#if defined(__linux__)
    // Only consider files >= 3MiB
    if (absl::GetFlag(FLAGS_drop_log_memory) && file_length_ >= (3 << 20)) {
      // Don't evict the most recent 1-2MiB so as not to impact a tailer
      // of the log file and to avoid page rounding issue on linux < 4.7
      uint32_t total_drop_length =
          (file_length_ & ~((1 << 20) - 1)) - (1 << 20);
      uint32_t this_drop_length = total_drop_length - dropped_mem_length_;
      if (this_drop_length >= (2 << 20)) {
        // Only advise when >= 2MiB to drop
        posix_fadvise(fileno(file_), dropped_mem_length_, this_drop_length,
                      POSIX_FADV_DONTNEED);
        dropped_mem_length_ = total_drop_length;
      }
    }
#endif
  }
}

}  // namespace

// Static log data space to avoid alloc failures in a LOG(FATAL)
//
// Since multiple threads may call LOG(FATAL), and we want to preserve
// the data from the first call, we allocate two sets of space.  One
// for exclusive use by the first thread, and one for shared use by
// all other threads.
static absl::Mutex fatal_msg_lock;
static logging_internal::CrashReason crash_reason;
static bool fatal_msg_exclusive = true;
static LogMessage::LogMessageData fatal_msg_data_exclusive;
static LogMessage::LogMessageData fatal_msg_data_shared;

// Static thread-local log data space to use, because typically at most one
// LogMessageData object exists (in this case glog makes zero heap memory
// allocations).
static thread_local bool thread_data_available = true;

static thread_local std::aligned_storage<
    sizeof(LogMessage::LogMessageData),
    alignof(LogMessage::LogMessageData)>::type thread_msg_data;

LogMessage::LogMessageData::LogMessageData()
    : stream_(message_text_, LogMessage::kMaxLogMessageLen, 0) {}

LogMessage::LogMessage(const char* file, int line, LogSeverity severity,
                       int ctr, void (LogMessage::*send_method)())
    : allocated_(NULL) {
  Init(file, line, severity, send_method);
  data_->stream_.set_ctr(ctr);
}

LogMessage::LogMessage(const char* file, int line, const CheckOpString& result)
    : allocated_(NULL) {
  Init(file, line, GLOG_FATAL, &LogMessage::SendToLog);
  stream() << "Check failed: " << (*result.str_) << " ";
}

LogMessage::LogMessage(const char* file, int line) : allocated_(NULL) {
  Init(file, line, GLOG_INFO, &LogMessage::SendToLog);
}

LogMessage::LogMessage(const char* file, int line, LogSeverity severity)
    : allocated_(NULL) {
  Init(file, line, severity, &LogMessage::SendToLog);
}

LogMessage::LogMessage(const char* file, int line, LogSeverity severity,
                       LogSink* sink, bool also_send_to_log)
    : allocated_(NULL) {
  Init(file, line, severity,
       also_send_to_log ? &LogMessage::SendToSinkAndLog
                        : &LogMessage::SendToSink);
  data_->sink_ = sink;  // override Init()'s setting to NULL
}

LogMessage::LogMessage(const char* file, int line, LogSeverity severity,
                       vector<string>* outvec)
    : allocated_(NULL) {
  Init(file, line, severity, &LogMessage::SaveOrSendToLog);
  data_->outvec_ = outvec;  // override Init()'s setting to NULL
}

LogMessage::LogMessage(const char* file, int line, LogSeverity severity,
                       string* message)
    : allocated_(NULL) {
  Init(file, line, severity, &LogMessage::WriteToStringAndLog);
  data_->message_ = message;  // override Init()'s setting to NULL
}

void LogMessage::Init(const char* file, int line, LogSeverity severity,
                      void (LogMessage::*send_method)()) {
  allocated_ = NULL;
  if (severity != GLOG_FATAL || !exit_on_dfatal) {
    // No need for locking, because this is thread local.
    if (thread_data_available) {
      thread_data_available = false;
      data_ = new (&thread_msg_data) LogMessageData;
    } else {
      allocated_ = new LogMessageData();
      data_ = allocated_;
    }
    data_->first_fatal_ = false;
  } else {
    absl::MutexLock l(&fatal_msg_lock);
    if (fatal_msg_exclusive) {
      fatal_msg_exclusive = false;
      data_ = &fatal_msg_data_exclusive;
      data_->first_fatal_ = true;
    } else {
      data_ = &fatal_msg_data_shared;
      data_->first_fatal_ = false;
    }
  }

  stream().fill('0');
  data_->preserved_errno_ = errno;
  data_->severity_ = severity;
  data_->line_ = line;
  data_->send_method_ = send_method;
  data_->sink_ = NULL;
  data_->outvec_ = NULL;
  double now = ToUDate(absl::Now());
  data_->timestamp_ = static_cast<time_t>(now);
  localtime_r(&data_->timestamp_, &data_->tm_time_);
  int usecs = static_cast<int>((now - data_->timestamp_) * 1000000);

  data_->num_chars_to_log_ = 0;
  data_->num_chars_to_syslog_ = 0;
  data_->basename_ = logging_internal::const_basename(file);
  data_->fullname_ = file;
  data_->has_been_flushed_ = false;

  // If specified, prepend a prefix to each line.  For example:
  //    I1018 160715 f5d4fbb0 logging.cc:1153]
  //    (log level, GMT month, date, time, thread_id, file basename, line)
  // We exclude the thread_id for the default thread.
  if (absl::GetFlag(FLAGS_log_prefix) && (line != kNoLogPrefix)) {
    stream() << LogSeverityNames[severity][0] << setw(2)
             << 1 + data_->tm_time_.tm_mon << setw(2) << data_->tm_time_.tm_mday
             << ' ' << setw(2) << data_->tm_time_.tm_hour << ':' << setw(2)
             << data_->tm_time_.tm_min << ':' << setw(2)
             << data_->tm_time_.tm_sec << "." << setw(6) << usecs << ' '
             << setfill(' ') << setw(5) << logging_internal::GetTID()
             << setfill('0') << ' ' << data_->basename_ << ':' << data_->line_
             << "] ";
  }
  data_->num_prefix_chars_ = data_->stream_.pcount();

  if (!absl::GetFlag(FLAGS_log_backtrace_at).empty()) {
    char fileline[128];
    snprintf(fileline, sizeof(fileline), "%s:%d", data_->basename_, line);
    if (!strcmp(absl::GetFlag(FLAGS_log_backtrace_at).c_str(), fileline)) {
      string stacktrace;
      logging_internal::DumpStackTraceToString(&stacktrace);
      stream() << " (stacktrace:\n" << stacktrace << ") ";
    }
  }
}

LogMessage::~LogMessage() {
  Flush();
#ifdef GLOG_THREAD_LOCAL_STORAGE
  if (data_ == static_cast<void*>(&thread_msg_data)) {
    data_->~LogMessageData();
    thread_data_available = true;
  } else {
    delete allocated_;
  }
#else   // !defined(GLOG_THREAD_LOCAL_STORAGE)
  delete allocated_;
#endif  // defined(GLOG_THREAD_LOCAL_STORAGE)
}

int LogMessage::preserved_errno() const { return data_->preserved_errno_; }

ostream& LogMessage::stream() { return data_->stream_; }

// Flush buffered message, called by the destructor, or any other function
// that needs to synchronize the log.
void LogMessage::Flush() {
  if (data_->has_been_flushed_ ||
      data_->severity_ < absl::GetFlag(FLAGS_minloglevel))
    return;

  data_->num_chars_to_log_ = data_->stream_.pcount();
  data_->num_chars_to_syslog_ =
      data_->num_chars_to_log_ - data_->num_prefix_chars_;

  // Do we need to add a \n to the end of this message?
  bool append_newline =
      (data_->message_text_[data_->num_chars_to_log_ - 1] != '\n');
  char original_final_char = '\0';

  // If we do need to add a \n, we'll do it by violating the memory of the
  // ostrstream buffer.  This is quick, and we'll make sure to undo our
  // modification before anything else is done with the ostrstream.  It
  // would be preferable not to do things this way, but it seems to be
  // the best way to deal with this.
  if (append_newline) {
    original_final_char = data_->message_text_[data_->num_chars_to_log_];
    data_->message_text_[data_->num_chars_to_log_++] = '\n';
  }

  // Prevent any subtle race conditions by wrapping a absl::Mutex lock around
  // the actual logging action per se.
  {
    absl::MutexLock l(&log_mutex);
    (this->*(data_->send_method_))();
    ++num_messages_[static_cast<int>(data_->severity_)];
  }
  LogDestination::WaitForSinks(data_);

  if (append_newline) {
    // Fix the ostrstream back how it was before we screwed with it.
    // It's 99.44% certain that we don't need to worry about doing this.
    data_->message_text_[data_->num_chars_to_log_ - 1] = original_final_char;
  }

  // If errno was already set before we enter the logging call, we'll
  // set it back to that value when we return from the logging call.
  // It happens often that we log an error message after a syscall
  // failure, which can potentially set the errno to some other
  // values.  We would like to preserve the original errno.
  if (data_->preserved_errno_ != 0) {
    errno = data_->preserved_errno_;
  }

  // Note that this message is now safely logged.  If we're asked to flush
  // again, as a result of destruction, say, we'll do nothing on future calls.
  data_->has_been_flushed_ = true;
}

// Copy of first FATAL log message so that we can print it out again
// after all the stack traces.  To preserve legacy behavior, we don't
// use fatal_msg_data_exclusive.
static time_t fatal_time;
static char fatal_message[256];

void ReprintFatalMessage() {
  if (fatal_message[0]) {
    const int n = strlen(fatal_message);
    if (!absl::GetFlag(FLAGS_logtostderr)) {
      // Also write to stderr (don't color to avoid terminal checks)
      WriteToStderr(fatal_message, n);
    }
    LogDestination::LogToAllLogfiles(GLOG_ERROR, fatal_time, fatal_message, n);
  }
}

// L >= log_mutex (callers must hold the log_mutex).
void LogMessage::SendToLog() EXCLUSIVE_LOCKS_REQUIRED(log_mutex) {
  static bool already_warned_before_initgoogle = false;

  log_mutex.AssertHeld();

  RAW_DCHECK(data_->num_chars_to_log_ > 0 &&
                 data_->message_text_[data_->num_chars_to_log_ - 1] == '\n',
             "");

  // Messages of a given severity get logged to lower severity logs, too

  if (!already_warned_before_initgoogle &&
      !logging_internal::IsGoogleLoggingInitialized()) {
    const char w[] =
        "WARNING: Logging before InitGoogleLogging() is "
        "written to STDERR\n";
    WriteToStderr(w, strlen(w));
    already_warned_before_initgoogle = true;
  }

  // global flag: never log to file if set.  Also -- don't log to a
  // file if we haven't parsed the command line flags to get the
  // program name.
  if (absl::GetFlag(FLAGS_logtostderr) ||
      !logging_internal::IsGoogleLoggingInitialized()) {
    ColoredWriteToStderr(data_->severity_, data_->message_text_,
                         data_->num_chars_to_log_);

    // this could be protected by a flag if necessary.
    LogDestination::LogToSinks(
        data_->severity_, data_->fullname_, data_->basename_, data_->line_,
        &data_->tm_time_, data_->message_text_ + data_->num_prefix_chars_,
        (data_->num_chars_to_log_ - data_->num_prefix_chars_ - 1));
  } else {
    // log this message to all log files of severity <= severity_
    LogDestination::LogToAllLogfiles(data_->severity_, data_->timestamp_,
                                     data_->message_text_,
                                     data_->num_chars_to_log_);

    LogDestination::MaybeLogToStderr(data_->severity_, data_->message_text_,
                                     data_->num_chars_to_log_);
    LogDestination::LogToSinks(
        data_->severity_, data_->fullname_, data_->basename_, data_->line_,
        &data_->tm_time_, data_->message_text_ + data_->num_prefix_chars_,
        (data_->num_chars_to_log_ - data_->num_prefix_chars_ - 1));
    // NOTE: -1 removes trailing \n
  }

  // If we log a FATAL message, flush all the log destinations, then toss
  // a signal for others to catch. We leave the logs in a state that
  // someone else can use them (as long as they flush afterwards)
  if (data_->severity_ == GLOG_FATAL && exit_on_dfatal) {
    if (data_->first_fatal_) {
      // Store crash information so that it is accessible from within signal
      // handlers that may be invoked later.
      RecordCrashReason(&crash_reason);
      SetCrashReason(&crash_reason);

      // Store shortened fatal message for other logs and GWQ status
      const int copy =
          min<int>(data_->num_chars_to_log_, sizeof(fatal_message) - 1);
      memcpy(fatal_message, data_->message_text_, copy);
      fatal_message[copy] = '\0';
      fatal_time = data_->timestamp_;
    }

    if (!absl::GetFlag(FLAGS_logtostderr)) {
      for (int i = 0; i < NUM_SEVERITIES; ++i) {
        if (LogDestination::log_destinations_[i])
          LogDestination::log_destinations_[i]->logger_->Write(true, 0, "", 0);
      }
    }

    // release the lock that our caller (directly or indirectly)
    // LogMessage::~LogMessage() grabbed so that signal handlers
    // can use the logging facility. Alternately, we could add
    // an entire unsafe logging interface to bypass locking
    // for signal handlers but this seems simpler.
    log_mutex.Unlock();
    LogDestination::WaitForSinks(data_);

    const char* message = "*** Check failure stack trace: ***\n";
    if (write(STDERR_FILENO, message, strlen(message)) < 0) {
      // Ignore errors.
    }
    Fail();
  }
}

void LogMessage::RecordCrashReason(logging_internal::CrashReason* reason) {
  reason->filename = fatal_msg_data_exclusive.fullname_;
  reason->line_number = fatal_msg_data_exclusive.line_;
  reason->message = fatal_msg_data_exclusive.message_text_ +
                    fatal_msg_data_exclusive.num_prefix_chars_;
  // Retrieve the stack trace, omitting the logging frames that got us here.
  reason->depth =
      absl::GetStackTrace(reason->stack, ABSL_ARRAYSIZE(reason->stack), 4);
}

#if !defined(_MSC_VER)
#define ATTRIBUTE_NORETURN __attribute__((noreturn))
#else
#define ATTRIBUTE_NORETURN
#endif

#if defined(_MSC_VER)
__declspec(noreturn)
#endif
    static void logging_fail() ATTRIBUTE_NORETURN;

static void logging_fail() { abort(); }

typedef void (*logging_fail_func_t)() ATTRIBUTE_NORETURN;

GOOGLE_GLOG_DLL_DECL
logging_fail_func_t g_logging_fail_func = &logging_fail;

void InstallFailureFunction(void (*fail_func)()) {
  g_logging_fail_func = (logging_fail_func_t)fail_func;
}

void LogMessage::Fail() { g_logging_fail_func(); }

// L >= log_mutex (callers must hold the log_mutex).
void LogMessage::SendToSink() EXCLUSIVE_LOCKS_REQUIRED(log_mutex) {
  if (data_->sink_ != NULL) {
    RAW_DCHECK(data_->num_chars_to_log_ > 0 &&
                   data_->message_text_[data_->num_chars_to_log_ - 1] == '\n',
               "");
    data_->sink_->send(
        data_->severity_, data_->fullname_, data_->basename_, data_->line_,
        &data_->tm_time_, data_->message_text_ + data_->num_prefix_chars_,
        (data_->num_chars_to_log_ - data_->num_prefix_chars_ - 1));
  }
}

// L >= log_mutex (callers must hold the log_mutex).
void LogMessage::SendToSinkAndLog() EXCLUSIVE_LOCKS_REQUIRED(log_mutex) {
  SendToSink();
  SendToLog();
}

// L >= log_mutex (callers must hold the log_mutex).
void LogMessage::SaveOrSendToLog() EXCLUSIVE_LOCKS_REQUIRED(log_mutex) {
  if (data_->outvec_ != NULL) {
    RAW_DCHECK(data_->num_chars_to_log_ > 0 &&
                   data_->message_text_[data_->num_chars_to_log_ - 1] == '\n',
               "");
    // Omit prefix of message and trailing newline when recording in outvec_.
    const char* start = data_->message_text_ + data_->num_prefix_chars_;
    int len = data_->num_chars_to_log_ - data_->num_prefix_chars_ - 1;
    data_->outvec_->push_back(string(start, len));
  } else {
    SendToLog();
  }
}

void LogMessage::WriteToStringAndLog() EXCLUSIVE_LOCKS_REQUIRED(log_mutex) {
  if (data_->message_ != NULL) {
    RAW_DCHECK(data_->num_chars_to_log_ > 0 &&
                   data_->message_text_[data_->num_chars_to_log_ - 1] == '\n',
               "");
    // Omit prefix of message and trailing newline when writing to message_.
    const char* start = data_->message_text_ + data_->num_prefix_chars_;
    int len = data_->num_chars_to_log_ - data_->num_prefix_chars_ - 1;
    data_->message_->assign(start, len);
  }
  SendToLog();
}

// L >= log_mutex (callers must hold the log_mutex).
void LogMessage::SendToSyslogAndLog() {
#if !defined(_MSC_VER)
  // Before any calls to syslog(), make a single call to openlog()
  static bool openlog_already_called = false;
  if (!openlog_already_called) {
    openlog(logging_internal::ProgramInvocationShortName(),
            LOG_CONS | LOG_NDELAY | LOG_PID, LOG_USER);
    openlog_already_called = true;
  }

  // This array maps Google severity levels to syslog levels
  const int SEVERITY_TO_LEVEL[] = {LOG_INFO, LOG_WARNING, LOG_ERR, LOG_EMERG};
  syslog(LOG_USER | SEVERITY_TO_LEVEL[static_cast<int>(data_->severity_)],
         "%.*s", static_cast<int>(data_->num_chars_to_syslog_),
         data_->message_text_ + data_->num_prefix_chars_);
  SendToLog();
#else
  LOG(ERROR) << "No syslog support: message=" << data_->message_text_;
#endif
}

base::Logger* base::GetLogger(LogSeverity severity) {
  absl::MutexLock l(&log_mutex);
  return LogDestination::log_destination(severity)->logger_;
}

void base::SetLogger(LogSeverity severity, base::Logger* logger) {
  absl::MutexLock l(&log_mutex);
  LogDestination::log_destination(severity)->logger_ = logger;
}

// L < log_mutex.  Acquires and releases absl::Mutex_.
int64_t LogMessage::num_messages(int severity) {
  absl::MutexLock l(&log_mutex);
  return num_messages_[severity];
}

// Output the COUNTER value. This is only valid if ostream is a
// LogStream.
ostream& operator<<(ostream& os, const PRIVATE_Counter&) {
#ifdef DISABLE_RTTI
  LogMessage::LogStream* log = static_cast<LogMessage::LogStream*>(&os);
#else
  LogMessage::LogStream* log = dynamic_cast<LogMessage::LogStream*>(&os);
#endif
  CHECK(log && log == log->self())
      << "You must not use COUNTER with non-glog ostream";
  os << log->ctr();
  return os;
}

ErrnoLogMessage::ErrnoLogMessage(const char* file, int line,
                                 LogSeverity severity, int ctr,
                                 void (LogMessage::*send_method)())
    : LogMessage(file, line, severity, ctr, send_method) {}

ErrnoLogMessage::~ErrnoLogMessage() {
  // Don't access errno directly because it may have been altered
  // while streaming the message.
  stream() << ": " << StrError(preserved_errno()) << " [" << preserved_errno()
           << "]";
}

void FlushLogFiles(LogSeverity min_severity) {
  LogDestination::FlushLogFiles(min_severity);
}

void FlushLogFilesUnsafe(LogSeverity min_severity) {
  LogDestination::FlushLogFilesUnsafe(min_severity);
}

void SetLogDestination(LogSeverity severity, const char* base_filename) {
  LogDestination::SetLogDestination(severity, base_filename);
}

void SetLogSymlink(LogSeverity severity, const char* symlink_basename) {
  LogDestination::SetLogSymlink(severity, symlink_basename);
}

LogSink::~LogSink() {}

void LogSink::WaitTillSent() {
  // noop default
}

string LogSink::ToString(LogSeverity severity, const char* file, int line,
                         const struct ::tm* tm_time, const char* message,
                         size_t message_len) {
  ostringstream stream(string(message, message_len));
  stream.fill('0');

  // FIXME(jrvb): Updating this to use the correct value for usecs
  // requires changing the signature for both this method and
  // LogSink::send().  This change needs to be done in a separate CL
  // so subclasses of LogSink can be updated at the same time.
  int usecs = 0;

  stream << LogSeverityNames[severity][0] << setw(2) << 1 + tm_time->tm_mon
         << setw(2) << tm_time->tm_mday << ' ' << setw(2) << tm_time->tm_hour
         << ':' << setw(2) << tm_time->tm_min << ':' << setw(2)
         << tm_time->tm_sec << '.' << setw(6) << usecs << ' ' << setfill(' ')
         << setw(5) << logging_internal::GetTID() << setfill('0') << ' ' << file
         << ':' << line << "] ";

  stream << string(message, message_len);
  return stream.str();
}

void AddLogSink(LogSink* destination) {
  LogDestination::AddLogSink(destination);
}

void RemoveLogSink(LogSink* destination) {
  LogDestination::RemoveLogSink(destination);
}

void SetLogFilenameExtension(const char* ext) {
  LogDestination::SetLogFilenameExtension(ext);
}

void SetStderrLogging(LogSeverity min_severity) {
  LogDestination::SetStderrLogging(min_severity);
}

void LogToStderr() { LogDestination::LogToStderr(); }

namespace base {
namespace internal {

bool GetExitOnDFatal();
bool GetExitOnDFatal() {
  absl::MutexLock l(&log_mutex);
  return exit_on_dfatal;
}

// Determines whether we exit the program for a LOG(DFATAL) message in
// debug mode.  It does this by skipping the call to Fail/FailQuietly.
// This is intended for testing only.
//
// This can have some effects on LOG(FATAL) as well.  Failure messages
// are always allocated (rather than sharing a buffer), the crash
// reason is not recorded, the "gwq" status message is not updated,
// and the stack trace is not recorded.  The LOG(FATAL) *will* still
// exit the program.  Since this function is used only in testing,
// these differences are acceptable.
void SetExitOnDFatal(bool value);
void SetExitOnDFatal(bool value) {
  absl::MutexLock l(&log_mutex);
  exit_on_dfatal = value;
}

}  // namespace internal
}  // namespace base

// Shell-escaping as we need to shell out ot /bin/mail.
static const char kDontNeedShellEscapeChars[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+-_.=/:,@";

static string ShellEscape(const string& src) {
  string result;
  if (!src.empty() &&  // empty string needs quotes
      src.find_first_not_of(kDontNeedShellEscapeChars) == string::npos) {
    // only contains chars that don't need quotes; it's fine
    result.assign(src);
  } else if (src.find_first_of('\'') == string::npos) {
    // no single quotes; just wrap it in single quotes
    result.assign("'");
    result.append(src);
    result.append("'");
  } else {
    // needs double quote escaping
    result.assign("\"");
    for (size_t i = 0; i < src.size(); ++i) {
      switch (src[i]) {
        case '\\':
        case '$':
        case '"':
        case '`':
          result.append("\\");
      }
      result.append(src, i, 1);
    }
    result.append("\"");
  }
  return result;
}

static void GetTempDirectories(vector<string>* list) {
  list->clear();
#ifdef _MSC_VER
  // On windows we'll try to find a directory in this order:
  //   C:/Documents & Settings/whomever/TEMP (or whatever GetTempPath() is)
  //   C:/TMP/
  //   C:/TEMP/
  //   C:/WINDOWS/ or C:/WINNT/
  //   .
  char tmp[MAX_PATH];
  if (GetTempPathA(MAX_PATH, tmp)) list->push_back(tmp);
  list->push_back("C:\\tmp\\");
  list->push_back("C:\\temp\\");
#else
  // Directories, in order of preference. If we find a dir that
  // exists, we stop adding other less-preferred dirs
  const char* candidates[] = {
      // Non-null only during unittest/regtest
      getenv("TEST_TMPDIR"),

      // Explicitly-supplied temp dirs
      getenv("TMPDIR"),
      getenv("TMP"),

      // If all else fails
      "/tmp",
  };

  for (size_t i = 0; i < ABSL_ARRAYSIZE(candidates); i++) {
    const char* d = candidates[i];
    if (!d) continue;  // Empty env var

    // Make sure we don't surprise anyone who's expecting a '/'
    string dstr = d;
    if (dstr[dstr.size() - 1] != '/') {
      dstr += "/";
    }
    list->push_back(dstr);

    struct stat statbuf;
    if (!stat(d, &statbuf) && S_ISDIR(statbuf.st_mode)) {
      // We found a dir that exists - we're done.
      return;
    }
  }

#endif
}

static vector<string>* logging_directories_list;

const vector<string>& GetLoggingDirectories() {
  // Not strictly thread-safe but we're called early in InitGoogle().
  if (logging_directories_list == NULL) {
    logging_directories_list = new vector<string>;

    if (!absl::GetFlag(FLAGS_log_dir).empty()) {
      // A dir was specified, we should use it
      logging_directories_list->push_back(absl::GetFlag(FLAGS_log_dir).c_str());
    } else {
      GetTempDirectories(logging_directories_list);
#ifdef _MSC_VER
      char tmp[MAX_PATH];
      if (GetWindowsDirectoryA(tmp, MAX_PATH))
        logging_directories_list->push_back(tmp);
      logging_directories_list->push_back(".\\");
#else
      logging_directories_list->push_back("./");
#endif
    }
  }
  return *logging_directories_list;
}

void TestOnly_ClearLoggingDirectoriesList() {
  fprintf(stderr,
          "TestOnly_ClearLoggingDirectoriesList should only be "
          "called from test code.\n");
  delete logging_directories_list;
  logging_directories_list = NULL;
}

void GetExistingTempDirectories(vector<string>* list) {
  GetTempDirectories(list);
  vector<string>::iterator i_dir = list->begin();
  while (i_dir != list->end()) {
    // zero arg to access means test for existence; no constant
    // defined on windows
    if (access(i_dir->c_str(), 0)) {
      i_dir = list->erase(i_dir);
    } else {
      ++i_dir;
    }
  }
}

// Helper functions for string comparisons.
#define DEFINE_CHECK_STROP_IMPL(name, func, expected)                         \
  string* Check##func##expected##Impl(const char* s1, const char* s2,         \
                                      const char* names) {                    \
    bool equal = s1 == s2 || (s1 && s2 && !func(s1, s2));                     \
    if (equal == expected) {                                                  \
      return NULL;                                                            \
    } else {                                                                  \
      ostringstream ss;                                                       \
      if (!s1) s1 = "";                                                       \
      if (!s2) s2 = "";                                                       \
      ss << #name " failed: " << names << " (" << s1 << " vs. " << s2 << ")"; \
      return new string(ss.str());                                            \
    }                                                                         \
  }
DEFINE_CHECK_STROP_IMPL(CHECK_STREQ, strcmp, true)
DEFINE_CHECK_STROP_IMPL(CHECK_STRNE, strcmp, false)
DEFINE_CHECK_STROP_IMPL(CHECK_STRCASEEQ, strcasecmp, true)
DEFINE_CHECK_STROP_IMPL(CHECK_STRCASENE, strcasecmp, false)
#undef DEFINE_CHECK_STROP_IMPL

int posix_strerror_r(int err, char* buf, size_t len) {
  // Sanity check input parameters
  if (buf == NULL || len <= 0) {
    errno = EINVAL;
    return -1;
  }

  // Reset buf and errno, and try calling whatever version of strerror_r()
  // is implemented by glibc
  buf[0] = '\000';
  int old_errno = errno;
  errno = 0;
  char* rc = reinterpret_cast<char*>(strerror_r(err, buf, len));

  // Both versions set errno on failure
  if (errno) {
    // Should already be there, but better safe than sorry
    buf[0] = '\000';
    return -1;
  }
  errno = old_errno;

  // POSIX is vague about whether the string will be terminated, although
  // is indirectly implies that typically ERANGE will be returned, instead
  // of truncating the string. This is different from the GNU implementation.
  // We play it safe by always terminating the string explicitly.
  buf[len - 1] = '\000';

  // If the function succeeded, we can use its exit code to determine the
  // semantics implemented by glibc
  if (!rc) {
    return 0;
  } else {
    // GNU semantics detected
    if (rc == buf) {
      return 0;
    } else {
      buf[0] = '\000';
#if defined(OS_MACOSX) || defined(OS_FREEBSD) || defined(OS_OPENBSD)
      if (reinterpret_cast<intptr_t>(rc) < sys_nerr) {
        // This means an error on MacOSX or FreeBSD.
        return -1;
      }
#endif
      strncat(buf, rc, len - 1);
      return 0;
    }
  }
}

string StrError(int err) {
  char buf[100];
  int rc = posix_strerror_r(err, buf, sizeof(buf));
  if ((rc < 0) || (buf[0] == '\000')) {
    snprintf(buf, sizeof(buf), "Error number %d", err);
  }
  return buf;
}

LogMessageFatal::LogMessageFatal(const char* file, int line)
    : LogMessage(file, line, GLOG_FATAL) {}

LogMessageFatal::LogMessageFatal(const char* file, int line,
                                 const CheckOpString& result)
    : LogMessage(file, line, result) {}

LogMessageFatal::~LogMessageFatal() {
  Flush();
  LogMessage::Fail();
}

namespace base {

CheckOpMessageBuilder::CheckOpMessageBuilder(const char* exprtext)
    : stream_(new ostringstream) {
  *stream_ << exprtext << " (";
}

CheckOpMessageBuilder::~CheckOpMessageBuilder() { delete stream_; }

ostream* CheckOpMessageBuilder::ForVar2() {
  *stream_ << " vs. ";
  return stream_;
}

string* CheckOpMessageBuilder::NewString() {
  *stream_ << ")";
  return new string(stream_->str());
}

}  // namespace base

template <>
void MakeCheckOpValueString(std::ostream* os, const char& v) {
  if (v >= 32 && v <= 126) {
    (*os) << "'" << v << "'";
  } else {
    (*os) << "char value " << (int16_t)v;
  }
}

template <>
void MakeCheckOpValueString(std::ostream* os, const signed char& v) {
  if (v >= 32 && v <= 126) {
    (*os) << "'" << v << "'";
  } else {
    (*os) << "signed char value " << (int16_t)v;
  }
}

template <>
void MakeCheckOpValueString(std::ostream* os, const unsigned char& v) {
  if (v >= 32 && v <= 126) {
    (*os) << "'" << v << "'";
  } else {
    (*os) << "unsigned char value " << (uint16_t)v;
  }
}

template <>
void MakeCheckOpValueString(std::ostream* os, const std::nullptr_t& v) {
  (*os) << "nullptr";
}

void InitGoogleLogging(const char* argv0) {
  logging_internal::InitGoogleLoggingUtilities(argv0);
}

void ShutdownGoogleLogging() {
  logging_internal::ShutdownGoogleLoggingUtilities();
  LogDestination::DeleteLogDestinations();
  delete logging_directories_list;
  logging_directories_list = NULL;
}

}  // namespace google