// Copyright 2012 The Chromium Authors // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef BASE_LOGGING_H_ #define BASE_LOGGING_H_ #include <stddef.h> #include <cassert> #include <cstdint> #include <sstream> #include <string> #include <string_view> #include "base/base_export.h" #include "base/compiler_specific.h" #include "base/dcheck_is_on.h" #include "base/files/file_path.h" #include "base/functional/callback_forward.h" #include "base/strings/utf_ostream_operators.h" #include "build/build_config.h" #include "build/chromeos_buildflags.h" #if BUILDFLAG(IS_CHROMEOS) #include <cstdio> #include "base/memory/raw_ptr.h" #endif #if BUILDFLAG(IS_WIN) #include "base/win/windows_types.h" #endif // // Optional message capabilities // ----------------------------- // Assertion failed messages and fatal errors are displayed in a dialog box // before the application exits. However, running this UI creates a message // loop, which causes application messages to be processed and potentially // dispatched to existing application windows. Since the application is in a // bad state when this assertion dialog is displayed, these messages may not // get processed and hang the dialog, or the application might go crazy. // // Therefore, it can be beneficial to display the error dialog in a separate // process from the main application. When the logging system needs to display // a fatal error dialog box, it will look for a program called // "DebugMessage.exe" in the same directory as the application executable. It // will run this application with the message as the command line, and will // not include the name of the application as is traditional for easier // parsing. // // The code for DebugMessage.exe is only one line. In WinMain, do: // MessageBox(NULL, GetCommandLineW(), L"Fatal Error", 0); // // If DebugMessage.exe is not found, the logging code will use a normal // MessageBox, potentially causing the problems discussed above. // Instructions // ------------ // // Make a bunch of macros for logging. The way to log things is to stream // things to LOG(<a particular severity level>). E.g., // // LOG(INFO) << "Found " << num_cookies << " cookies"; // // You can also do conditional logging: // // LOG_IF(INFO, num_cookies > 10) << "Got lots of cookies"; // // The CHECK(condition) macro is active in both debug and release builds and // effectively performs a LOG(FATAL) which terminates the process and // generates a crashdump unless a debugger is attached. // // There are also "debug mode" logging macros like the ones above: // // DLOG(INFO) << "Found cookies"; // // DLOG_IF(INFO, num_cookies > 10) << "Got lots of cookies"; // // All "debug mode" logging is compiled away to nothing for non-debug mode // compiles. LOG_IF and development flags also work well together // because the code can be compiled away sometimes. // // We also have // // LOG_ASSERT(assertion); // DLOG_ASSERT(assertion); // // which is syntactic sugar for {,D}LOG_IF(FATAL, assert fails) << assertion; // // There are "verbose level" logging macros. They look like // // VLOG(1) << "I'm printed when you run the program with --v=1 or more"; // VLOG(2) << "I'm printed when you run the program with --v=2 or more"; // // These always log at the INFO log level (when they log at all). // // The verbose logging can also be turned on module-by-module. For instance, // --vmodule=profile=2,icon_loader=1,browser_*=3,*/chromeos/*=4 --v=0 // will cause: // a. VLOG(2) and lower messages to be printed from profile.{h,cc} // b. VLOG(1) and lower messages to be printed from icon_loader.{h,cc} // c. VLOG(3) and lower messages to be printed from files prefixed with // "browser" // d. VLOG(4) and lower messages to be printed from files under a // "chromeos" directory. // e. VLOG(0) and lower messages to be printed from elsewhere // // The wildcarding functionality shown by (c) supports both '*' (match // 0 or more characters) and '?' (match any single character) // wildcards. Any pattern containing a forward or backward slash will // be tested against the whole pathname and not just the module. // E.g., "*/foo/bar/*=2" would change the logging level for all code // in source files under a "foo/bar" directory. // // Note that for a Chromium binary built in release mode (is_debug = false) you // must pass "--enable-logging=stderr" in order to see the output of VLOG // statements. // // There's also VLOG_IS_ON(n) "verbose level" condition macro. To be used as // // if (VLOG_IS_ON(2)) { // // do some logging preparation and logging // // that can't be accomplished with just VLOG(2) << ...; // } // // There is also a VLOG_IF "verbose level" condition macro for sample // cases, when some extra computation and preparation for logs is not // needed. // // VLOG_IF(1, (size > 1024)) // << "I'm printed when size is more than 1024 and when you run the " // "program with --v=1 or more"; // // We also override the standard 'assert' to use 'DLOG_ASSERT'. // // Lastly, there is: // // PLOG(ERROR) << "Couldn't do foo"; // DPLOG(ERROR) << "Couldn't do foo"; // PLOG_IF(ERROR, cond) << "Couldn't do foo"; // DPLOG_IF(ERROR, cond) << "Couldn't do foo"; // PCHECK(condition) << "Couldn't do foo"; // DPCHECK(condition) << "Couldn't do foo"; // // which append the last system error to the message in string form (taken from // GetLastError() on Windows and errno on POSIX). // // The supported severity levels for macros that allow you to specify one // are (in increasing order of severity) INFO, WARNING, ERROR, and FATAL. // // Very important: logging a message at the FATAL severity level causes // the program to terminate (after the message is logged). // // There is the special severity of DFATAL, which logs FATAL in DCHECK-enabled // builds, ERROR in normal mode. // // Output is formatted as per the following example, except on Chrome OS. // [3816:3877:0812/234555.406952:VERBOSE1:drm_device_handle.cc(90)] Succeeded // authenticating /dev/dri/card0 in 0 ms with 1 attempt(s) // // The colon separated fields inside the brackets are as follows: // 0. An optional Logfile prefix (not included in this example) // 1. Process ID // 2. Thread ID // 3. The date/time of the log message, in MMDD/HHMMSS.Milliseconds format // 4. The log level // 5. The filename and line number where the log was instantiated // // Output for Chrome OS can be switched to syslog-like format. See // InitWithSyslogPrefix() in logging_chromeos.cc for details. // // Note that the visibility can be changed by setting preferences in // SetLogItems() // // Additional logging-related information can be found here: // https://chromium.googlesource.com/chromium/src/+/main/docs/linux/debugging.md#Logging namespace logging { // A bitmask of potential logging destinations. LoggingDestination; // Specifies where logs will be written. Multiple destinations can be specified // with bitwise OR. // Unless destination is LOG_NONE, all logs with severity ERROR and above will // be written to stderr in addition to the specified destination. // LOG_TO_FILE includes logging to externally-provided file handles. enum : uint32_t { … }; // Indicates that the log file should be locked when being written to. // Unless there is only one single-threaded process that is logging to // the log file, the file should be locked during writes to make each // log output atomic. Other writers will block. // // All processes writing to the log file must have their locking set for it to // work properly. Defaults to LOCK_LOG_FILE. enum LogLockingState { … }; // On startup, should we delete or append to an existing log file (if any)? // Defaults to APPEND_TO_OLD_LOG_FILE. enum OldFileDeletionState { … }; #if BUILDFLAG(IS_CHROMEOS) // Defines the log message prefix format to use. // LOG_FORMAT_SYSLOG indicates syslog-like message prefixes. // LOG_FORMAT_CHROME indicates the normal Chrome format. enum class BASE_EXPORT LogFormat { LOG_FORMAT_CHROME, LOG_FORMAT_SYSLOG }; #endif struct BASE_EXPORT LoggingSettings { … }; // Define different names for the BaseInitLoggingImpl() function depending on // whether NDEBUG is defined or not so that we'll fail to link if someone tries // to compile logging.cc with NDEBUG but includes logging.h without defining it, // or vice versa. #if defined(NDEBUG) #define BaseInitLoggingImpl … #else #define BaseInitLoggingImpl … #endif // Implementation of the InitLogging() method declared below. We use a // more-specific name so we can #define it above without affecting other code // that has named stuff "InitLogging". BASE_EXPORT bool BaseInitLoggingImpl(const LoggingSettings& settings); // Sets the log file name and other global logging state. Calling this function // is recommended, and is normally done at the beginning of application init. // If you don't call it, all the flags will be initialized to their default // values, and there is a race condition that may leak a critical section // object if two threads try to do the first log at the same time. // See the definition of the enums above for descriptions and default values. // // The default log file is initialized to "debug.log" in the application // directory. You probably don't want this, especially since the program // directory may not be writable on an enduser's system. // // This function may be called a second time to re-direct logging (e.g after // loging in to a user partition), however it should never be called more than // twice. inline bool InitLogging(const LoggingSettings& settings) { … } // Sets the log level. Anything at or above this level will be written to the // log file/displayed to the user (if applicable). Anything below this level // will be silently ignored. The log level defaults to 0 (everything is logged // up to level INFO) if this function is not called. // Note that log messages for VLOG(x) are logged at level -x, so setting // the min log level to negative values enables verbose logging and conversely, // setting the VLOG default level will set this min level to a negative number, // effectively enabling all levels of logging. BASE_EXPORT void SetMinLogLevel(int level); // Gets the current log level. BASE_EXPORT int GetMinLogLevel(); // Used by LOG_IS_ON to lazy-evaluate stream arguments. BASE_EXPORT bool ShouldCreateLogMessage(int severity); // Gets the VLOG default verbosity level. BASE_EXPORT int GetVlogVerbosity(); // Note that |N| is the size *with* the null terminator. BASE_EXPORT int GetVlogLevelHelper(const char* file_start, size_t N); // Gets the current vlog level for the given file (usually taken from __FILE__). template <size_t N> int GetVlogLevel(const char (&file)[N]) { … } // Sets the common items you want to be prepended to each log message. // process and thread IDs default to off, the timestamp defaults to on. // If this function is not called, logging defaults to writing the timestamp // only. BASE_EXPORT void SetLogItems(bool enable_process_id, bool enable_thread_id, bool enable_timestamp, bool enable_tickcount); // Sets an optional prefix to add to each log message. |prefix| is not copied // and should be a raw string constant. |prefix| must only contain ASCII letters // to avoid confusion with PIDs and timestamps. Pass null to remove the prefix. // Logging defaults to no prefix. BASE_EXPORT void SetLogPrefix(const char* prefix); // Sets whether or not you'd like to see fatal debug messages popped up in // a dialog box or not. // Dialogs are not shown by default. BASE_EXPORT void SetShowErrorDialogs(bool enable_dialogs); // Registers an abort hook with absl that will crash the process similarly to a // `CHECK` failure in case of a FATAL error in absl (e.g., any operation that // would throw an exception). BASE_EXPORT void RegisterAbslAbortHook(); // Sets the Log Assert Handler that will be used to notify of check failures. // Resets Log Assert Handler on object destruction. // The default handler shows a dialog box and then terminate the process, // however clients can use this function to override with their own handling // (e.g. a silent one for Unit Tests) LogAssertHandlerFunction; class BASE_EXPORT ScopedLogAssertHandler { … }; // Sets the Log Message Handler that gets passed every log message before // it's sent to other log destinations (if any). // Returns true to signal that it handled the message and the message // should not be sent to other log destinations. LogMessageHandlerFunction; BASE_EXPORT void SetLogMessageHandler(LogMessageHandlerFunction handler); BASE_EXPORT LogMessageHandlerFunction GetLogMessageHandler(); LogSeverity; constexpr LogSeverity LOGGING_VERBOSE = …; // This is level 1 verbosity // Note: the log severities are used to index into the array of names, // see log_severity_names. constexpr LogSeverity LOGGING_INFO = …; constexpr LogSeverity LOGGING_WARNING = …; constexpr LogSeverity LOGGING_ERROR = …; constexpr LogSeverity LOGGING_FATAL = …; constexpr LogSeverity LOGGING_NUM_SEVERITIES = …; // LOGGING_DFATAL is LOGGING_FATAL in DCHECK-enabled builds, ERROR in normal // mode. #if DCHECK_IS_ON() constexpr LogSeverity LOGGING_DFATAL = …; #else constexpr LogSeverity LOGGING_DFATAL = LOGGING_ERROR; #endif // A few definitions of macros that don't generate much code. These are used // by LOG() and LOG_IF, etc. Since these are used all over our code, it's // better to have compact code for these operations. #define COMPACT_GOOGLE_LOG_EX_INFO(ClassName, ...) … #define COMPACT_GOOGLE_LOG_EX_WARNING(ClassName, ...) … #define COMPACT_GOOGLE_LOG_EX_ERROR(ClassName, ...) … #define COMPACT_GOOGLE_LOG_EX_FATAL(ClassName, ...) … #define COMPACT_GOOGLE_LOG_EX_DFATAL(ClassName, ...) … #define COMPACT_GOOGLE_LOG_INFO … #define COMPACT_GOOGLE_LOG_WARNING … #define COMPACT_GOOGLE_LOG_ERROR … #define COMPACT_GOOGLE_LOG_FATAL … #define COMPACT_GOOGLE_LOG_DFATAL … #if BUILDFLAG(IS_WIN) // wingdi.h defines ERROR to be 0. When we call LOG(ERROR), it gets // substituted with 0, and it expands to COMPACT_GOOGLE_LOG_0. To allow us // to keep using this syntax, we define this macro to do the same thing // as COMPACT_GOOGLE_LOG_ERROR, and also define ERROR the same way that // the Windows SDK does for consistency. #define ERROR … #define COMPACT_GOOGLE_LOG_EX_0 … #define COMPACT_GOOGLE_LOG_0 … // Needed for LOG_IS_ON(ERROR). constexpr LogSeverity LOGGING_0 = LOGGING_ERROR; #endif // As special cases, we can assume that LOG_IS_ON(FATAL) always holds. Also, // LOG_IS_ON(DFATAL) always holds in debug mode. In particular, CHECK()s will // always fire if they fail. // FATAL is always enabled and required to be resolved in compile time for // LOG(FATAL) to be properly understood as [[noreturn]]. #define LOG_IS_ON(severity) … // Define a default ENABLED_VLOG_LEVEL if it is not defined. The macros allows // code to enable vlog level at build time without the need of --vmodule // switch at runtime. This is intended for VLOGs that needed from production // code without the cpu overhead to match vmodule patterns on every VLOG // instance. #if !defined(ENABLED_VLOG_LEVEL) #define ENABLED_VLOG_LEVEL … #endif // !defined(ENABLED_VLOG_LEVEL) // We don't do any caching tricks with VLOG_IS_ON() like the // google-glog version since it increases binary size. This means // that using the v-logging functions in conjunction with --vmodule // may be slow. #define VLOG_IS_ON(verboselevel) … // Helper macro which avoids evaluating the arguments to a stream if // the condition doesn't hold. Condition is evaluated once and only once. #define LAZY_STREAM(stream, condition) … // We use the preprocessor's merging operator, "##", so that, e.g., // LOG(INFO) becomes the token COMPACT_GOOGLE_LOG_INFO. There's some funny // subtle difference between ostream member streaming functions (e.g., // ostream::operator<<(int) and ostream non-member streaming functions // (e.g., ::operator<<(ostream&, string&): it turns out that it's // impossible to stream something like a string directly to an unnamed // ostream. We employ a neat hack by calling the stream() member // function of LogMessage which seems to avoid the problem. #define LOG_STREAM(severity) … #define LOG(severity) … #define LOG_IF(severity, condition) … // The VLOG macros log with negative verbosities. #define VLOG_STREAM(verbose_level) … #define VLOG(verbose_level) … #define VLOG_IF(verbose_level, condition) … #if BUILDFLAG(IS_WIN) #define VPLOG_STREAM … #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA) #define VPLOG_STREAM(verbose_level) … #endif #define VPLOG(verbose_level) … #define VPLOG_IF(verbose_level, condition) … // TODO(akalin): Add more VLOG variants, e.g. VPLOG. #define LOG_ASSERT(condition) … #if BUILDFLAG(IS_WIN) #define PLOG_STREAM … #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA) #define PLOG_STREAM(severity) … #endif #define PLOG(severity) … #define PLOG_IF(severity, condition) … BASE_EXPORT extern std::ostream* g_swallow_stream; // Note that g_swallow_stream is used instead of an arbitrary LOG() stream to // avoid the creation of an object with a non-trivial destructor (LogMessage). // On MSVC x86 (checked on 2015 Update 3), this causes a few additional // pointless instructions to be emitted even at full optimization level, even // though the : arm of the ternary operator is clearly never executed. Using a // simpler object to be &'d with Voidify() avoids these extra instructions. // Using a simpler POD object with a templated operator<< also works to avoid // these instructions. However, this causes warnings on statically defined // implementations of operator<<(std::ostream, ...) in some .cc files, because // they become defined-but-unreferenced functions. A reinterpret_cast of 0 to an // ostream* also is not suitable, because some compilers warn of undefined // behavior. #define EAT_STREAM_PARAMETERS … // Definitions for DLOG et al. #if DCHECK_IS_ON() // All of these definitions use DLOG_IS_ON() rather than define to their LOG() // equivalents, as DLOG(FATAL) and friends can't be understood as [[noreturn]] // but LOG(FATAL) is. #define DLOG_IS_ON(severity) … #define DLOG(severity) … #define DLOG_IF(severity, condition) … #define DPLOG(severity) … #define DPLOG_IF(severity, condition) … #define DVLOG_IF(verboselevel, condition) … #define DVPLOG_IF(verboselevel, condition) … #define DLOG_ASSERT(condition) … #else // DCHECK_IS_ON() // If !DCHECK_IS_ON(), we want to avoid emitting any references to |condition| // (which may reference a variable defined only if DCHECK_IS_ON()). // Contrast this with DCHECK et al., which has different behavior. #define DLOG_IS_ON … #define DLOG … #define DLOG_IF … #define DPLOG … #define DPLOG_IF … #define DVLOG_IF … #define DVPLOG_IF … #define DLOG_ASSERT … #endif // DCHECK_IS_ON() #define DVLOG(verboselevel) … #define DVPLOG(verboselevel) … // Definitions for DCHECK et al. // TODO(pbos): Move this to check.h. Probably find a better name. Maybe this // means that we want LogSeverity in a separate file, but maybe we can just have // this as a bool DCHECK_IS_FATAL. #if BUILDFLAG(DCHECK_IS_CONFIGURABLE) BASE_EXPORT extern LogSeverity LOGGING_DCHECK; #else constexpr LogSeverity LOGGING_DCHECK = …; #endif // BUILDFLAG(DCHECK_IS_CONFIGURABLE) // Redefine the standard assert to use our nice log files #undef assert #define assert(x) … // This class more or less represents a particular log message. You // create an instance of LogMessage and then stream stuff to it. // When you finish streaming to it, ~LogMessage is called and the // full message gets streamed to the appropriate destination. // // You shouldn't actually use LogMessage's constructor to log things, // though. You should use the LOG() macro (and variants thereof) // above. class BASE_EXPORT LogMessage { … }; class BASE_EXPORT LogMessageFatal final : public LogMessage { … }; // This class is used to explicitly ignore values in the conditional // logging macros. This avoids compiler warnings like "value computed // is not used" and "statement has no effect". class LogMessageVoidify { … }; #if BUILDFLAG(IS_WIN) typedef unsigned long SystemErrorCode; #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA) SystemErrorCode; #endif // Alias for ::GetLastError() on Windows and errno on POSIX. Avoids having to // pull in windows.h just for GetLastError() and DWORD. BASE_EXPORT SystemErrorCode GetLastSystemErrorCode(); BASE_EXPORT std::string SystemErrorCodeToString(SystemErrorCode error_code); #if BUILDFLAG(IS_WIN) // Appends a formatted system message of the GetLastError() type. class BASE_EXPORT Win32ErrorLogMessage : public LogMessage { public: Win32ErrorLogMessage(const char* file, int line, LogSeverity severity, SystemErrorCode err); Win32ErrorLogMessage(const Win32ErrorLogMessage&) = delete; Win32ErrorLogMessage& operator=(const Win32ErrorLogMessage&) = delete; // Appends the error message before destructing the encapsulated class. ~Win32ErrorLogMessage() override; protected: void AppendError(); private: SystemErrorCode err_; }; class BASE_EXPORT Win32ErrorLogMessageFatal final : public Win32ErrorLogMessage { public: using Win32ErrorLogMessage::Win32ErrorLogMessage; [[noreturn]] ~Win32ErrorLogMessageFatal() override; }; #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA) // Appends a formatted system message of the errno type class BASE_EXPORT ErrnoLogMessage : public LogMessage { … }; class BASE_EXPORT ErrnoLogMessageFatal final : public ErrnoLogMessage { … }; #endif // BUILDFLAG(IS_WIN) // Closes the log file explicitly if open. // NOTE: Since the log file is opened as necessary by the action of logging // statements, there's no guarantee that it will stay closed // after this call. BASE_EXPORT void CloseLogFile(); #if BUILDFLAG(IS_CHROMEOS_ASH) // Returns a new file handle that will write to the same destination as the // currently open log file. Returns nullptr if logging to a file is disabled, // or if opening the file failed. This is intended to be used to initialize // logging in child processes that are unable to open files. BASE_EXPORT FILE* DuplicateLogFILE(); #endif // Async signal safe logging mechanism. BASE_EXPORT void RawLog(int level, const char* message); #define RAW_LOG(level, message) … #if BUILDFLAG(IS_WIN) // Returns true if logging to file is enabled. BASE_EXPORT bool IsLoggingToFileEnabled(); // Returns the default log file path. BASE_EXPORT std::wstring GetLogFileFullPath(); // Duplicates the log file handle to send into a child process. BASE_EXPORT HANDLE DuplicateLogFileHandle(); #endif } // namespace logging #endif // BASE_LOGGING_H_
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