// Copyright (c) 2012 The Chromium Authors. All rights reserved. // 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 #include #include #include #include #include #include #include "base/base_export.h" #include "base/callback_forward.h" #include "base/compiler_specific.h" #include "base/debug/debugger.h" #include "base/macros.h" #include "base/strings/string_piece_forward.h" #include "base/template_util.h" #include "build/build_config.h" // // 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(). 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. // // 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 debug mode, // ERROR in normal mode. namespace logging { // TODO(avi): do we want to do a unification of character types here? #if defined(OS_WIN) typedef wchar_t PathChar; #elif defined(OS_POSIX) || defined(OS_FUCHSIA) typedef char PathChar; #endif // Where to record logging output? A flat file and/or system debug log // via OutputDebugString. enum LoggingDestination { LOG_NONE = 0, LOG_TO_FILE = 1 << 0, LOG_TO_SYSTEM_DEBUG_LOG = 1 << 1, LOG_TO_ALL = LOG_TO_FILE | LOG_TO_SYSTEM_DEBUG_LOG, // On Windows, use a file next to the exe; on POSIX platforms, where // it may not even be possible to locate the executable on disk, use // stderr. #if defined(OS_WIN) LOG_DEFAULT = LOG_TO_FILE, #elif defined(OS_POSIX) || defined(OS_FUCHSIA) LOG_DEFAULT = LOG_TO_SYSTEM_DEBUG_LOG, #endif }; // 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 { LOCK_LOG_FILE, DONT_LOCK_LOG_FILE }; // On startup, should we delete or append to an existing log file (if any)? // Defaults to APPEND_TO_OLD_LOG_FILE. enum OldFileDeletionState { DELETE_OLD_LOG_FILE, APPEND_TO_OLD_LOG_FILE }; struct BASE_EXPORT LoggingSettings { // The defaults values are: // // logging_dest: LOG_DEFAULT // log_file: NULL // lock_log: LOCK_LOG_FILE // delete_old: APPEND_TO_OLD_LOG_FILE LoggingSettings(); LoggingDestination logging_dest; // The three settings below have an effect only when LOG_TO_FILE is // set in |logging_dest|. const PathChar* log_file; LogLockingState lock_log; OldFileDeletionState delete_old; }; // 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 BaseInitLoggingImpl_built_with_NDEBUG #else #define BaseInitLoggingImpl BaseInitLoggingImpl_built_without_NDEBUG #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) { return BaseInitLoggingImpl(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. 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 int GetVlogLevel(const char (&file)[N]) { return GetVlogLevelHelper(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 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); // 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) using LogAssertHandlerFunction = base::Callback; class BASE_EXPORT ScopedLogAssertHandler { public: explicit ScopedLogAssertHandler(LogAssertHandlerFunction handler); ~ScopedLogAssertHandler(); private: DISALLOW_COPY_AND_ASSIGN(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. typedef bool (*LogMessageHandlerFunction)(int severity, const char* file, int line, size_t message_start, const std::string& str); BASE_EXPORT void SetLogMessageHandler(LogMessageHandlerFunction handler); BASE_EXPORT LogMessageHandlerFunction GetLogMessageHandler(); // The ANALYZER_ASSUME_TRUE(bool arg) macro adds compiler-specific hints // to Clang which control what code paths are statically analyzed, // and is meant to be used in conjunction with assert & assert-like functions. // The expression is passed straight through if analysis isn't enabled. // // ANALYZER_SKIP_THIS_PATH() suppresses static analysis for the current // codepath and any other branching codepaths that might follow. #if defined(__clang_analyzer__) inline constexpr bool AnalyzerNoReturn() __attribute__((analyzer_noreturn)) { return false; } inline constexpr bool AnalyzerAssumeTrue(bool arg) { // AnalyzerNoReturn() is invoked and analysis is terminated if |arg| is // false. return arg || AnalyzerNoReturn(); } #define ANALYZER_ASSUME_TRUE(arg) logging::AnalyzerAssumeTrue(!!(arg)) #define ANALYZER_SKIP_THIS_PATH() \ static_cast(::logging::AnalyzerNoReturn()) #define ANALYZER_ALLOW_UNUSED(var) static_cast(var); #else // !defined(__clang_analyzer__) #define ANALYZER_ASSUME_TRUE(arg) (arg) #define ANALYZER_SKIP_THIS_PATH() #define ANALYZER_ALLOW_UNUSED(var) static_cast(var); #endif // defined(__clang_analyzer__) typedef int LogSeverity; const LogSeverity LOG_VERBOSE = -1; // This is level 1 verbosity // Note: the log severities are used to index into the array of names, // see log_severity_names. const LogSeverity LOG_INFO = 0; const LogSeverity LOG_WARNING = 1; const LogSeverity LOG_ERROR = 2; const LogSeverity LOG_FATAL = 3; const LogSeverity LOG_NUM_SEVERITIES = 4; // LOG_DFATAL is LOG_FATAL in debug mode, ERROR in normal mode #if defined(NDEBUG) const LogSeverity LOG_DFATAL = LOG_ERROR; #else const LogSeverity LOG_DFATAL = LOG_FATAL; #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, ...) \ ::logging::ClassName(__FILE__, __LINE__, ::logging::LOG_INFO, ##__VA_ARGS__) #define COMPACT_GOOGLE_LOG_EX_WARNING(ClassName, ...) \ ::logging::ClassName(__FILE__, __LINE__, ::logging::LOG_WARNING, \ ##__VA_ARGS__) #define COMPACT_GOOGLE_LOG_EX_ERROR(ClassName, ...) \ ::logging::ClassName(__FILE__, __LINE__, ::logging::LOG_ERROR, ##__VA_ARGS__) #define COMPACT_GOOGLE_LOG_EX_FATAL(ClassName, ...) \ ::logging::ClassName(__FILE__, __LINE__, ::logging::LOG_FATAL, ##__VA_ARGS__) #define COMPACT_GOOGLE_LOG_EX_DFATAL(ClassName, ...) \ ::logging::ClassName(__FILE__, __LINE__, ::logging::LOG_DFATAL, ##__VA_ARGS__) #define COMPACT_GOOGLE_LOG_EX_DCHECK(ClassName, ...) \ ::logging::ClassName(__FILE__, __LINE__, ::logging::LOG_DCHECK, ##__VA_ARGS__) #define COMPACT_GOOGLE_LOG_INFO COMPACT_GOOGLE_LOG_EX_INFO(LogMessage) #define COMPACT_GOOGLE_LOG_WARNING COMPACT_GOOGLE_LOG_EX_WARNING(LogMessage) #define COMPACT_GOOGLE_LOG_ERROR COMPACT_GOOGLE_LOG_EX_ERROR(LogMessage) #define COMPACT_GOOGLE_LOG_FATAL COMPACT_GOOGLE_LOG_EX_FATAL(LogMessage) #define COMPACT_GOOGLE_LOG_DFATAL COMPACT_GOOGLE_LOG_EX_DFATAL(LogMessage) #define COMPACT_GOOGLE_LOG_DCHECK COMPACT_GOOGLE_LOG_EX_DCHECK(LogMessage) #if defined(OS_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 0 #define COMPACT_GOOGLE_LOG_EX_0(ClassName, ...) \ COMPACT_GOOGLE_LOG_EX_ERROR(ClassName , ##__VA_ARGS__) #define COMPACT_GOOGLE_LOG_0 COMPACT_GOOGLE_LOG_ERROR // Needed for LOG_IS_ON(ERROR). const LogSeverity LOG_0 = LOG_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. #define LOG_IS_ON(severity) \ (::logging::ShouldCreateLogMessage(::logging::LOG_##severity)) // We can't do any caching tricks with VLOG_IS_ON() like the // google-glog version since it requires GCC extensions. This means // that using the v-logging functions in conjunction with --vmodule // may be slow. #define VLOG_IS_ON(verboselevel) \ ((verboselevel) <= ::logging::GetVlogLevel(__FILE__)) // 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) \ !(condition) ? (void) 0 : ::logging::LogMessageVoidify() & (stream) // 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) COMPACT_GOOGLE_LOG_ ## severity.stream() #define LOG(severity) LAZY_STREAM(LOG_STREAM(severity), LOG_IS_ON(severity)) #define LOG_IF(severity, condition) \ LAZY_STREAM(LOG_STREAM(severity), LOG_IS_ON(severity) && (condition)) // The VLOG macros log with negative verbosities. #define VLOG_STREAM(verbose_level) \ ::logging::LogMessage(__FILE__, __LINE__, -verbose_level).stream() #define VLOG(verbose_level) \ LAZY_STREAM(VLOG_STREAM(verbose_level), VLOG_IS_ON(verbose_level)) #define VLOG_IF(verbose_level, condition) \ LAZY_STREAM(VLOG_STREAM(verbose_level), \ VLOG_IS_ON(verbose_level) && (condition)) #if defined (OS_WIN) #define VPLOG_STREAM(verbose_level) \ ::logging::Win32ErrorLogMessage(__FILE__, __LINE__, -verbose_level, \ ::logging::GetLastSystemErrorCode()).stream() #elif defined(OS_POSIX) || defined(OS_FUCHSIA) #define VPLOG_STREAM(verbose_level) \ ::logging::ErrnoLogMessage(__FILE__, __LINE__, -verbose_level, \ ::logging::GetLastSystemErrorCode()).stream() #endif #define VPLOG(verbose_level) \ LAZY_STREAM(VPLOG_STREAM(verbose_level), VLOG_IS_ON(verbose_level)) #define VPLOG_IF(verbose_level, condition) \ LAZY_STREAM(VPLOG_STREAM(verbose_level), \ VLOG_IS_ON(verbose_level) && (condition)) // TODO(akalin): Add more VLOG variants, e.g. VPLOG. #define LOG_ASSERT(condition) \ LOG_IF(FATAL, !(ANALYZER_ASSUME_TRUE(condition))) \ << "Assert failed: " #condition ". " #if defined(OS_WIN) #define PLOG_STREAM(severity) \ COMPACT_GOOGLE_LOG_EX_ ## severity(Win32ErrorLogMessage, \ ::logging::GetLastSystemErrorCode()).stream() #elif defined(OS_POSIX) || defined(OS_FUCHSIA) #define PLOG_STREAM(severity) \ COMPACT_GOOGLE_LOG_EX_ ## severity(ErrnoLogMessage, \ ::logging::GetLastSystemErrorCode()).stream() #endif #define PLOG(severity) \ LAZY_STREAM(PLOG_STREAM(severity), LOG_IS_ON(severity)) #define PLOG_IF(severity, condition) \ LAZY_STREAM(PLOG_STREAM(severity), LOG_IS_ON(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 \ true ? (void)0 \ : ::logging::LogMessageVoidify() & (*::logging::g_swallow_stream) // Captures the result of a CHECK_EQ (for example) and facilitates testing as a // boolean. class CheckOpResult { public: // |message| must be non-null if and only if the check failed. CheckOpResult(std::string* message) : message_(message) {} // Returns true if the check succeeded. operator bool() const { return !message_; } // Returns the message. std::string* message() { return message_; } private: std::string* message_; }; // Crashes in the fastest possible way with no attempt at logging. // There are different constraints to satisfy here, see http://crbug.com/664209 // for more context: // - The trap instructions, and hence the PC value at crash time, have to be // distinct and not get folded into the same opcode by the compiler. // On Linux/Android this is tricky because GCC still folds identical // asm volatile blocks. The workaround is generating distinct opcodes for // each CHECK using the __COUNTER__ macro. // - The debug info for the trap instruction has to be attributed to the source // line that has the CHECK(), to make crash reports actionable. This rules // out the ability of using a inline function, at least as long as clang // doesn't support attribute(artificial). // - Failed CHECKs should produce a signal that is distinguishable from an // invalid memory access, to improve the actionability of crash reports. // - The compiler should treat the CHECK as no-return instructions, so that the // trap code can be efficiently packed in the prologue of the function and // doesn't interfere with the main execution flow. // - When debugging, developers shouldn't be able to accidentally step over a // CHECK. This is achieved by putting opcodes that will cause a non // continuable exception after the actual trap instruction. // - Don't cause too much binary bloat. #if defined(COMPILER_GCC) #if defined(ARCH_CPU_X86_FAMILY) && !defined(OS_NACL) // int 3 will generate a SIGTRAP. #define TRAP_SEQUENCE() \ asm volatile( \ "int3; ud2; push %0;" ::"i"(static_cast(__COUNTER__))) #elif defined(ARCH_CPU_ARMEL) && !defined(OS_NACL) // bkpt will generate a SIGBUS when running on armv7 and a SIGTRAP when running // as a 32 bit userspace app on arm64. There doesn't seem to be any way to // cause a SIGTRAP from userspace without using a syscall (which would be a // problem for sandboxing). #define TRAP_SEQUENCE() \ asm volatile("bkpt #0; udf %0;" ::"i"(__COUNTER__ % 256)) #elif defined(ARCH_CPU_ARM64) && !defined(OS_NACL) // This will always generate a SIGTRAP on arm64. #define TRAP_SEQUENCE() \ asm volatile("brk #0; hlt %0;" ::"i"(__COUNTER__ % 65536)) #else // Crash report accuracy will not be guaranteed on other architectures, but at // least this will crash as expected. #define TRAP_SEQUENCE() __builtin_trap() #endif // ARCH_CPU_* // CHECK() and the trap sequence can be invoked from a constexpr function. // This could make compilation fail on GCC, as it forbids directly using inline // asm inside a constexpr function. However, it allows calling a lambda // expression including the same asm. // The side effect is that the top of the stacktrace will not point to the // calling function, but to this anonymous lambda. This is still useful as the // full name of the lambda will typically include the name of the function that // calls CHECK() and the debugger will still break at the right line of code. #if !defined(__clang__) #define WRAPPED_TRAP_SEQUENCE() \ do { \ [] { TRAP_SEQUENCE(); }(); \ } while (false) #else #define WRAPPED_TRAP_SEQUENCE() TRAP_SEQUENCE() #endif #define IMMEDIATE_CRASH() \ ({ \ WRAPPED_TRAP_SEQUENCE(); \ __builtin_unreachable(); \ }) #elif defined(COMPILER_MSVC) // Clang is cleverer about coalescing int3s, so we need to add a unique-ish // instruction following the __debugbreak() to have it emit distinct locations // for CHECKs rather than collapsing them all together. It would be nice to use // a short intrinsic to do this (and perhaps have only one implementation for // both clang and MSVC), however clang-cl currently does not support intrinsics. // On the flip side, MSVC x64 doesn't support inline asm. So, we have to have // two implementations. Normally clang-cl's version will be 5 bytes (1 for // `int3`, 2 for `ud2`, 2 for `push byte imm`, however, TODO(scottmg): // https://crbug.com/694670 clang-cl doesn't currently support %'ing // __COUNTER__, so eventually it will emit the dword form of push. // TODO(scottmg): Reinvestigate a short sequence that will work on both // compilers once clang supports more intrinsics. See https://crbug.com/693713. #if defined(__clang__) #define IMMEDIATE_CRASH() \ ({ \ {__asm int 3 __asm ud2 __asm push __COUNTER__}; \ __builtin_unreachable(); \ }) #else #define IMMEDIATE_CRASH() __debugbreak() #endif // __clang__ #else #error Port #endif // CHECK dies with a fatal error if condition is not true. It is *not* // controlled by NDEBUG, so the check will be executed regardless of // compilation mode. // // We make sure CHECK et al. always evaluates their arguments, as // doing CHECK(FunctionWithSideEffect()) is a common idiom. #if defined(OFFICIAL_BUILD) && defined(NDEBUG) // Make all CHECK functions discard their log strings to reduce code bloat, and // improve performance, for official release builds. // // This is not calling BreakDebugger since this is called frequently, and // calling an out-of-line function instead of a noreturn inline macro prevents // compiler optimizations. #define CHECK(condition) \ UNLIKELY(!(condition)) ? IMMEDIATE_CRASH() : EAT_STREAM_PARAMETERS // PCHECK includes the system error code, which is useful for determining // why the condition failed. In official builds, preserve only the error code // message so that it is available in crash reports. The stringified // condition and any additional stream parameters are dropped. #define PCHECK(condition) \ LAZY_STREAM(PLOG_STREAM(FATAL), UNLIKELY(!(condition))); \ EAT_STREAM_PARAMETERS #define CHECK_OP(name, op, val1, val2) CHECK((val1) op (val2)) #else // !(OFFICIAL_BUILD && NDEBUG) #if defined(_PREFAST_) && defined(OS_WIN) // Use __analysis_assume to tell the VC++ static analysis engine that // assert conditions are true, to suppress warnings. The LAZY_STREAM // parameter doesn't reference 'condition' in /analyze builds because // this evaluation confuses /analyze. The !! before condition is because // __analysis_assume gets confused on some conditions: // http://randomascii.wordpress.com/2011/09/13/analyze-for-visual-studio-the-ugly-part-5/ #define CHECK(condition) \ __analysis_assume(!!(condition)), \ LAZY_STREAM(LOG_STREAM(FATAL), false) \ << "Check failed: " #condition ". " #define PCHECK(condition) \ __analysis_assume(!!(condition)), \ LAZY_STREAM(PLOG_STREAM(FATAL), false) \ << "Check failed: " #condition ". " #else // _PREFAST_ // Do as much work as possible out of line to reduce inline code size. #define CHECK(condition) \ LAZY_STREAM(::logging::LogMessage(__FILE__, __LINE__, #condition).stream(), \ !ANALYZER_ASSUME_TRUE(condition)) #define PCHECK(condition) \ LAZY_STREAM(PLOG_STREAM(FATAL), !ANALYZER_ASSUME_TRUE(condition)) \ << "Check failed: " #condition ". " #endif // _PREFAST_ // Helper macro for binary operators. // Don't use this macro directly in your code, use CHECK_EQ et al below. // The 'switch' is used to prevent the 'else' from being ambiguous when the // macro is used in an 'if' clause such as: // if (a == 1) // CHECK_EQ(2, a); #define CHECK_OP(name, op, val1, val2) \ switch (0) case 0: default: \ if (::logging::CheckOpResult true_if_passed = \ ::logging::Check##name##Impl((val1), (val2), \ #val1 " " #op " " #val2)) \ ; \ else \ ::logging::LogMessage(__FILE__, __LINE__, true_if_passed.message()).stream() #endif // !(OFFICIAL_BUILD && NDEBUG) // This formats a value for a failing CHECK_XX statement. Ordinarily, // it uses the definition for operator<<, with a few special cases below. template inline typename std::enable_if< base::internal::SupportsOstreamOperator::value && !std::is_function::type>::value, void>::type MakeCheckOpValueString(std::ostream* os, const T& v) { (*os) << v; } // Provide an overload for functions and function pointers. Function pointers // don't implicitly convert to void* but do implicitly convert to bool, so // without this function pointers are always printed as 1 or 0. (MSVC isn't // standards-conforming here and converts function pointers to regular // pointers, so this is a no-op for MSVC.) template inline typename std::enable_if< std::is_function::type>::value, void>::type MakeCheckOpValueString(std::ostream* os, const T& v) { (*os) << reinterpret_cast(v); } // We need overloads for enums that don't support operator<<. // (i.e. scoped enums where no operator<< overload was declared). template inline typename std::enable_if< !base::internal::SupportsOstreamOperator::value && std::is_enum::value, void>::type MakeCheckOpValueString(std::ostream* os, const T& v) { (*os) << static_cast::type>(v); } // We need an explicit overload for std::nullptr_t. BASE_EXPORT void MakeCheckOpValueString(std::ostream* os, std::nullptr_t p); // Build the error message string. This is separate from the "Impl" // function template because it is not performance critical and so can // be out of line, while the "Impl" code should be inline. Caller // takes ownership of the returned string. template std::string* MakeCheckOpString(const t1& v1, const t2& v2, const char* names) { std::ostringstream ss; ss << names << " ("; MakeCheckOpValueString(&ss, v1); ss << " vs. "; MakeCheckOpValueString(&ss, v2); ss << ")"; std::string* msg = new std::string(ss.str()); return msg; } // Commonly used instantiations of MakeCheckOpString<>. Explicitly instantiated // in logging.cc. extern template BASE_EXPORT std::string* MakeCheckOpString( const int&, const int&, const char* names); extern template BASE_EXPORT std::string* MakeCheckOpString( const unsigned long&, const unsigned long&, const char* names); extern template BASE_EXPORT std::string* MakeCheckOpString( const unsigned long&, const unsigned int&, const char* names); extern template BASE_EXPORT std::string* MakeCheckOpString( const unsigned int&, const unsigned long&, const char* names); extern template BASE_EXPORT std::string* MakeCheckOpString( const std::string&, const std::string&, const char* name); // Helper functions for CHECK_OP macro. // The (int, int) specialization works around the issue that the compiler // will not instantiate the template version of the function on values of // unnamed enum type - see comment below. // // The checked condition is wrapped with ANALYZER_ASSUME_TRUE, which under // static analysis builds, blocks analysis of the current path if the // condition is false. #define DEFINE_CHECK_OP_IMPL(name, op) \ template \ inline std::string* Check##name##Impl(const t1& v1, const t2& v2, \ const char* names) { \ if (ANALYZER_ASSUME_TRUE(v1 op v2)) \ return NULL; \ else \ return ::logging::MakeCheckOpString(v1, v2, names); \ } \ inline std::string* Check##name##Impl(int v1, int v2, const char* names) { \ if (ANALYZER_ASSUME_TRUE(v1 op v2)) \ return NULL; \ else \ return ::logging::MakeCheckOpString(v1, v2, names); \ } DEFINE_CHECK_OP_IMPL(EQ, ==) DEFINE_CHECK_OP_IMPL(NE, !=) DEFINE_CHECK_OP_IMPL(LE, <=) DEFINE_CHECK_OP_IMPL(LT, < ) DEFINE_CHECK_OP_IMPL(GE, >=) DEFINE_CHECK_OP_IMPL(GT, > ) #undef DEFINE_CHECK_OP_IMPL #define CHECK_EQ(val1, val2) CHECK_OP(EQ, ==, val1, val2) #define CHECK_NE(val1, val2) CHECK_OP(NE, !=, val1, val2) #define CHECK_LE(val1, val2) CHECK_OP(LE, <=, val1, val2) #define CHECK_LT(val1, val2) CHECK_OP(LT, < , val1, val2) #define CHECK_GE(val1, val2) CHECK_OP(GE, >=, val1, val2) #define CHECK_GT(val1, val2) CHECK_OP(GT, > , val1, val2) #if defined(NDEBUG) && !defined(DCHECK_ALWAYS_ON) #define DCHECK_IS_ON() 0 #else #define DCHECK_IS_ON() 1 #endif // Definitions for DLOG et al. #if DCHECK_IS_ON() #define DLOG_IS_ON(severity) LOG_IS_ON(severity) #define DLOG_IF(severity, condition) LOG_IF(severity, condition) #define DLOG_ASSERT(condition) LOG_ASSERT(condition) #define DPLOG_IF(severity, condition) PLOG_IF(severity, condition) #define DVLOG_IF(verboselevel, condition) VLOG_IF(verboselevel, condition) #define DVPLOG_IF(verboselevel, condition) VPLOG_IF(verboselevel, 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(severity) false #define DLOG_IF(severity, condition) EAT_STREAM_PARAMETERS #define DLOG_ASSERT(condition) EAT_STREAM_PARAMETERS #define DPLOG_IF(severity, condition) EAT_STREAM_PARAMETERS #define DVLOG_IF(verboselevel, condition) EAT_STREAM_PARAMETERS #define DVPLOG_IF(verboselevel, condition) EAT_STREAM_PARAMETERS #endif // DCHECK_IS_ON() #define DLOG(severity) \ LAZY_STREAM(LOG_STREAM(severity), DLOG_IS_ON(severity)) #define DPLOG(severity) \ LAZY_STREAM(PLOG_STREAM(severity), DLOG_IS_ON(severity)) #define DVLOG(verboselevel) DVLOG_IF(verboselevel, VLOG_IS_ON(verboselevel)) #define DVPLOG(verboselevel) DVPLOG_IF(verboselevel, VLOG_IS_ON(verboselevel)) // Definitions for DCHECK et al. #if DCHECK_IS_ON() #if DCHECK_IS_CONFIGURABLE BASE_EXPORT extern LogSeverity LOG_DCHECK; #else const LogSeverity LOG_DCHECK = LOG_FATAL; #endif #else // DCHECK_IS_ON() // There may be users of LOG_DCHECK that are enabled independently // of DCHECK_IS_ON(), so default to FATAL logging for those. const LogSeverity LOG_DCHECK = LOG_FATAL; #endif // DCHECK_IS_ON() // DCHECK et al. make sure to reference |condition| regardless of // whether DCHECKs are enabled; this is so that we don't get unused // variable warnings if the only use of a variable is in a DCHECK. // This behavior is different from DLOG_IF et al. // // Note that the definition of the DCHECK macros depends on whether or not // DCHECK_IS_ON() is true. When DCHECK_IS_ON() is false, the macros use // EAT_STREAM_PARAMETERS to avoid expressions that would create temporaries. #if defined(_PREFAST_) && defined(OS_WIN) // See comments on the previous use of __analysis_assume. #define DCHECK(condition) \ __analysis_assume(!!(condition)), \ LAZY_STREAM(LOG_STREAM(DCHECK), false) \ << "Check failed: " #condition ". " #define DPCHECK(condition) \ __analysis_assume(!!(condition)), \ LAZY_STREAM(PLOG_STREAM(DCHECK), false) \ << "Check failed: " #condition ". " #else // !(defined(_PREFAST_) && defined(OS_WIN)) #if DCHECK_IS_ON() #define DCHECK(condition) \ LAZY_STREAM(LOG_STREAM(DCHECK), !ANALYZER_ASSUME_TRUE(condition)) \ << "Check failed: " #condition ". " #define DPCHECK(condition) \ LAZY_STREAM(PLOG_STREAM(DCHECK), !ANALYZER_ASSUME_TRUE(condition)) \ << "Check failed: " #condition ". " #else // DCHECK_IS_ON() #define DCHECK(condition) EAT_STREAM_PARAMETERS << !(condition) #define DPCHECK(condition) EAT_STREAM_PARAMETERS << !(condition) #endif // DCHECK_IS_ON() #endif // defined(_PREFAST_) && defined(OS_WIN) // Helper macro for binary operators. // Don't use this macro directly in your code, use DCHECK_EQ et al below. // The 'switch' is used to prevent the 'else' from being ambiguous when the // macro is used in an 'if' clause such as: // if (a == 1) // DCHECK_EQ(2, a); #if DCHECK_IS_ON() #define DCHECK_OP(name, op, val1, val2) \ switch (0) case 0: default: \ if (::logging::CheckOpResult true_if_passed = \ DCHECK_IS_ON() ? \ ::logging::Check##name##Impl((val1), (val2), \ #val1 " " #op " " #val2) : nullptr) \ ; \ else \ ::logging::LogMessage(__FILE__, __LINE__, ::logging::LOG_DCHECK, \ true_if_passed.message()).stream() #else // DCHECK_IS_ON() // When DCHECKs aren't enabled, DCHECK_OP still needs to reference operator<< // overloads for |val1| and |val2| to avoid potential compiler warnings about // unused functions. For the same reason, it also compares |val1| and |val2| // using |op|. // // Note that the contract of DCHECK_EQ, etc is that arguments are only evaluated // once. Even though |val1| and |val2| appear twice in this version of the macro // expansion, this is OK, since the expression is never actually evaluated. #define DCHECK_OP(name, op, val1, val2) \ EAT_STREAM_PARAMETERS << (::logging::MakeCheckOpValueString( \ ::logging::g_swallow_stream, val1), \ ::logging::MakeCheckOpValueString( \ ::logging::g_swallow_stream, val2), \ (val1)op(val2)) #endif // DCHECK_IS_ON() // Equality/Inequality checks - compare two values, and log a // LOG_DCHECK message including the two values when the result is not // as expected. The values must have operator<<(ostream, ...) // defined. // // You may append to the error message like so: // DCHECK_NE(1, 2) << "The world must be ending!"; // // We are very careful to ensure that each argument is evaluated exactly // once, and that anything which is legal to pass as a function argument is // legal here. In particular, the arguments may be temporary expressions // which will end up being destroyed at the end of the apparent statement, // for example: // DCHECK_EQ(string("abc")[1], 'b'); // // WARNING: These don't compile correctly if one of the arguments is a pointer // and the other is NULL. In new code, prefer nullptr instead. To // work around this for C++98, simply static_cast NULL to the type of the // desired pointer. #define DCHECK_EQ(val1, val2) DCHECK_OP(EQ, ==, val1, val2) #define DCHECK_NE(val1, val2) DCHECK_OP(NE, !=, val1, val2) #define DCHECK_LE(val1, val2) DCHECK_OP(LE, <=, val1, val2) #define DCHECK_LT(val1, val2) DCHECK_OP(LT, < , val1, val2) #define DCHECK_GE(val1, val2) DCHECK_OP(GE, >=, val1, val2) #define DCHECK_GT(val1, val2) DCHECK_OP(GT, > , val1, val2) #if !DCHECK_IS_ON() && defined(OS_CHROMEOS) // Implement logging of NOTREACHED() as a dedicated function to get function // call overhead down to a minimum. void LogErrorNotReached(const char* file, int line); #define NOTREACHED() \ true ? ::logging::LogErrorNotReached(__FILE__, __LINE__) \ : EAT_STREAM_PARAMETERS #else #define NOTREACHED() DCHECK(false) #endif // Redefine the standard assert to use our nice log files #undef assert #define assert(x) DLOG_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 { public: // Used for LOG(severity). LogMessage(const char* file, int line, LogSeverity severity); // Used for CHECK(). Implied severity = LOG_FATAL. LogMessage(const char* file, int line, const char* condition); // Used for CHECK_EQ(), etc. Takes ownership of the given string. // Implied severity = LOG_FATAL. LogMessage(const char* file, int line, std::string* result); // Used for DCHECK_EQ(), etc. Takes ownership of the given string. LogMessage(const char* file, int line, LogSeverity severity, std::string* result); ~LogMessage(); std::ostream& stream() { return stream_; } LogSeverity severity() { return severity_; } std::string str() { return stream_.str(); } private: void Init(const char* file, int line); LogSeverity severity_; std::ostringstream stream_; size_t message_start_; // Offset of the start of the message (past prefix // info). // The file and line information passed in to the constructor. const char* file_; const int line_; #if defined(OS_WIN) // Stores the current value of GetLastError in the constructor and restores // it in the destructor by calling SetLastError. // This is useful since the LogMessage class uses a lot of Win32 calls // that will lose the value of GLE and the code that called the log function // will have lost the thread error value when the log call returns. class SaveLastError { public: SaveLastError(); ~SaveLastError(); unsigned long get_error() const { return last_error_; } protected: unsigned long last_error_; }; SaveLastError last_error_; #endif DISALLOW_COPY_AND_ASSIGN(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 { public: LogMessageVoidify() = default; // This has to be an operator with a precedence lower than << but // higher than ?: void operator&(std::ostream&) { } }; #if defined(OS_WIN) typedef unsigned long SystemErrorCode; #elif defined(OS_POSIX) || defined(OS_FUCHSIA) typedef int 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 defined(OS_WIN) // Appends a formatted system message of the GetLastError() type. class BASE_EXPORT Win32ErrorLogMessage { public: Win32ErrorLogMessage(const char* file, int line, LogSeverity severity, SystemErrorCode err); // Appends the error message before destructing the encapsulated class. ~Win32ErrorLogMessage(); std::ostream& stream() { return log_message_.stream(); } private: SystemErrorCode err_; LogMessage log_message_; DISALLOW_COPY_AND_ASSIGN(Win32ErrorLogMessage); }; #elif defined(OS_POSIX) || defined(OS_FUCHSIA) // Appends a formatted system message of the errno type class BASE_EXPORT ErrnoLogMessage { public: ErrnoLogMessage(const char* file, int line, LogSeverity severity, SystemErrorCode err); // Appends the error message before destructing the encapsulated class. ~ErrnoLogMessage(); std::ostream& stream() { return log_message_.stream(); } private: SystemErrorCode err_; LogMessage log_message_; DISALLOW_COPY_AND_ASSIGN(ErrnoLogMessage); }; #endif // OS_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(); // Async signal safe logging mechanism. BASE_EXPORT void RawLog(int level, const char* message); #define RAW_LOG(level, message) \ ::logging::RawLog(::logging::LOG_##level, message) #define RAW_CHECK(condition) \ do { \ if (!(condition)) \ ::logging::RawLog(::logging::LOG_FATAL, \ "Check failed: " #condition "\n"); \ } while (0) #if defined(OS_WIN) // Returns true if logging to file is enabled. BASE_EXPORT bool IsLoggingToFileEnabled(); // Returns the default log file path. BASE_EXPORT std::wstring GetLogFileFullPath(); #endif } // namespace logging // Note that "The behavior of a C++ program is undefined if it adds declarations // or definitions to namespace std or to a namespace within namespace std unless // otherwise specified." --C++11[namespace.std] // // We've checked that this particular definition has the intended behavior on // our implementations, but it's prone to breaking in the future, and please // don't imitate this in your own definitions without checking with some // standard library experts. namespace std { // These functions are provided as a convenience for logging, which is where we // use streams (it is against Google style to use streams in other places). It // is designed to allow you to emit non-ASCII Unicode strings to the log file, // which is normally ASCII. It is relatively slow, so try not to use it for // common cases. Non-ASCII characters will be converted to UTF-8 by these // operators. BASE_EXPORT std::ostream& operator<<(std::ostream& out, const wchar_t* wstr); inline std::ostream& operator<<(std::ostream& out, const std::wstring& wstr) { return out << wstr.c_str(); } } // namespace std // The NOTIMPLEMENTED() macro annotates codepaths which have not been // implemented yet. If output spam is a serious concern, // NOTIMPLEMENTED_LOG_ONCE can be used. #if defined(COMPILER_GCC) // On Linux, with GCC, we can use __PRETTY_FUNCTION__ to get the demangled name // of the current function in the NOTIMPLEMENTED message. #define NOTIMPLEMENTED_MSG "Not implemented reached in " << __PRETTY_FUNCTION__ #else #define NOTIMPLEMENTED_MSG "NOT IMPLEMENTED" #endif #if defined(OS_ANDROID) && defined(OFFICIAL_BUILD) #define NOTIMPLEMENTED() EAT_STREAM_PARAMETERS #define NOTIMPLEMENTED_LOG_ONCE() EAT_STREAM_PARAMETERS #else #define NOTIMPLEMENTED() LOG(ERROR) << NOTIMPLEMENTED_MSG #define NOTIMPLEMENTED_LOG_ONCE() \ do { \ static bool logged_once = false; \ LOG_IF(ERROR, !logged_once) << NOTIMPLEMENTED_MSG; \ logged_once = true; \ } while (0); \ EAT_STREAM_PARAMETERS #endif #endif // BASE_LOGGING_H_