From 442f516c6215aa0bbdeec4c7f2d6c406521a92fd Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Sat, 23 Nov 2019 11:20:29 +0200 Subject: libcamera: Print backtrace on fatal errors When a fatal error occurs the program aborts, and all the logger provides is the location of the line that caused the error. Extend this with a full backtrace to help debugging. The backtrace is generated using the backtrace() call, a GNU extension to the C library. It is available in glibc and uClibc but not in musl. Test for availability of the function to condition compilation of the backtrace printing. Implementing backtrace support with musl is an exercise left to the reader if desired. The LogOutput class is extended to support writing string messages directly to the output. Strings written directly will be considered as LogDebug messages when written to the Syslog. Signed-off-by: Laurent Pinchart Tested-by: Kieran Bingham Reviewed-by: Kieran Bingham --- meson.build | 4 +++ src/libcamera/log.cpp | 93 +++++++++++++++++++++++++++++++++++++++++---------- 2 files changed, 79 insertions(+), 18 deletions(-) diff --git a/meson.build b/meson.build index 0a222ba9..63448858 100644 --- a/meson.build +++ b/meson.build @@ -26,6 +26,10 @@ libcamera_version = libcamera_git_version.split('+')[0] cc = meson.get_compiler('c') config_h = configuration_data() +if cc.has_header_symbol('execinfo.h', 'backtrace') + config_h.set('HAVE_BACKTRACE', 1) +endif + if cc.has_header_symbol('stdlib.h', 'secure_getenv', prefix : '#define _GNU_SOURCE') config_h.set('HAVE_SECURE_GETENV', 1) endif diff --git a/src/libcamera/log.cpp b/src/libcamera/log.cpp index 50f345b9..f4eb8c11 100644 --- a/src/libcamera/log.cpp +++ b/src/libcamera/log.cpp @@ -7,6 +7,9 @@ #include "log.h" +#if HAVE_BACKTRACE +#include +#endif #include #include #include @@ -108,10 +111,11 @@ public: bool isValid() const; void write(const LogMessage &msg); + void write(const std::string &msg); private: - void writeSyslog(const LogMessage &msg); - void writeStream(const LogMessage &msg); + void writeSyslog(LogSeverity severity, const std::string &msg); + void writeStream(const std::string &msg); std::ostream *stream_; LoggingTarget target_; @@ -180,34 +184,55 @@ bool LogOutput::isValid() const * \param[in] msg Message to write */ void LogOutput::write(const LogMessage &msg) +{ + std::string str; + + switch (target_) { + case LoggingTargetSyslog: + str = std::string(log_severity_name(msg.severity())) + " " + + msg.category().name() + " " + msg.fileInfo() + " " + + msg.msg(); + writeSyslog(msg.severity(), str); + break; + case LoggingTargetStream: + case LoggingTargetFile: + str = "[" + utils::time_point_to_string(msg.timestamp()) + "]" + + log_severity_name(msg.severity()) + " " + + msg.category().name() + " " + msg.fileInfo() + " " + + msg.msg(); + writeStream(str); + break; + default: + break; + } +} + +/** + * \brief Write string to log output + * \param[in] str String to write + */ +void LogOutput::write(const std::string &str) { switch (target_) { case LoggingTargetSyslog: - writeSyslog(msg); + writeSyslog(LogDebug, str); break; case LoggingTargetStream: case LoggingTargetFile: - writeStream(msg); + writeStream(str); break; default: break; } } -void LogOutput::writeSyslog(const LogMessage &msg) +void LogOutput::writeSyslog(LogSeverity severity, const std::string &str) { - std::string str = std::string(log_severity_name(msg.severity())) + " " + - msg.category().name() + " " + msg.fileInfo() + " " + - msg.msg(); - syslog(log_severity_to_syslog(msg.severity()), "%s", str.c_str()); + syslog(log_severity_to_syslog(severity), "%s", str.c_str()); } -void LogOutput::writeStream(const LogMessage &msg) +void LogOutput::writeStream(const std::string &str) { - std::string str = "[" + utils::time_point_to_string(msg.timestamp()) + - "]" + log_severity_name(msg.severity()) + " " + - msg.category().name() + " " + msg.fileInfo() + " " + - msg.msg(); stream_->write(str.c_str(), str.size()); stream_->flush(); } @@ -223,6 +248,7 @@ public: static Logger *instance(); void write(const LogMessage &msg); + void backtrace(); int logSetFile(const char *path); int logSetStream(std::ostream *stream); @@ -240,9 +266,6 @@ private: void registerCategory(LogCategory *category); void unregisterCategory(LogCategory *category); - void writeSyslog(const LogMessage &msg); - void writeStream(const LogMessage &msg); - std::unordered_set categories_; std::list> levels_; @@ -370,6 +393,38 @@ void Logger::write(const LogMessage &msg) output->write(msg); } +/** + * \brief Write a backtrace to the log + */ +void Logger::backtrace() +{ +#if HAVE_BACKTRACE + std::shared_ptr output = std::atomic_load(&output_); + if (!output) + return; + + void *buffer[32]; + int num_entries = ::backtrace(buffer, ARRAY_SIZE(buffer)); + char **strings = backtrace_symbols(buffer, num_entries); + if (!strings) + return; + + std::ostringstream msg; + msg << "Backtrace:" << std::endl; + + /* + * Skip the first two entries that correspond to this method and + * ~LogMessage(). + */ + for (int i = 2; i < num_entries; ++i) + msg << strings[i] << std::endl; + + output->write(msg.str()); + + free(strings); +#endif +} + /** * \brief Set the log file * \param[in] path Full path to the log file @@ -783,8 +838,10 @@ LogMessage::~LogMessage() if (severity_ >= category_.severity()) Logger::instance()->write(*this); - if (severity_ == LogSeverity::LogFatal) + if (severity_ == LogSeverity::LogFatal) { + Logger::instance()->backtrace(); std::abort(); + } } /** -- cgit v1.2.1