1  // Copyright (c) The Bitcoin Core developers
  2  // Distributed under the MIT software license, see the accompanying
  3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  4  
  5  #ifndef BITCOIN_UTIL_LOG_H
  6  #define BITCOIN_UTIL_LOG_H
  7  
  8  #include <logging/categories.h> // IWYU pragma: export
  9  #include <tinyformat.h>
 10  #include <util/check.h>
 11  
 12  #include <cstdint>
 13  #include <source_location>
 14  #include <string>
 15  #include <string_view>
 16  
 17  /// Like std::source_location, but allowing to override the function name.
 18  class SourceLocation
 19  {
 20  public:
 21      /// The func argument must be constructed from the C++11 __func__ macro.
 22      /// Ref: https://en.cppreference.com/w/cpp/language/function.html#func
 23      /// Non-static string literals are not supported.
 24      SourceLocation(const char* func,
 25                     std::source_location loc = std::source_location::current())
 26          : m_func{func}, m_loc{loc} {}
 27  
 28      std::string_view file_name() const { return m_loc.file_name(); }
 29      std::uint_least32_t line() const { return m_loc.line(); }
 30      std::string_view function_name_short() const { return m_func; }
 31  
 32  private:
 33      std::string_view m_func;
 34      std::source_location m_loc;
 35  };
 36  
 37  namespace util::log {
 38  /** Opaque to util::log; interpreted by consumers (e.g., BCLog::LogFlags). */
 39  using Category = uint64_t;
 40  
 41  enum class Level {
 42      Trace = 0, // High-volume or detailed logging for development/debugging
 43      Debug,     // Reasonably noisy logging, but still usable in production
 44      Info,      // Default
 45      Warning,
 46      Error,
 47  };
 48  
 49  struct Entry {
 50      Category category;
 51      Level level;
 52      bool should_ratelimit{false}; //!< Hint for consumers if this entry should be ratelimited
 53      SourceLocation source_loc;
 54      std::string message;
 55  };
 56  
 57  /** Return whether messages with specified category and level should be logged. Applications using
 58   * the logging library need to provide this. */
 59  bool ShouldLog(Category category, Level level);
 60  
 61  /** Send message to be logged. Applications using the logging library need to provide this. */
 62  void Log(Entry entry);
 63  } // namespace util::log
 64  
 65  namespace BCLog {
 66  //! Alias for compatibility. Prefer util::log::Level over BCLog::Level in new code.
 67  using Level = util::log::Level;
 68  } // namespace BCLog
 69  
 70  template <typename... Args>
 71  inline void LogPrintFormatInternal(SourceLocation&& source_loc, BCLog::LogFlags flag, BCLog::Level level, bool should_ratelimit, util::ConstevalFormatString<sizeof...(Args)> fmt, const Args&... args)
 72  {
 73      std::string log_msg;
 74      try {
 75          log_msg = tfm::format(fmt, args...);
 76      } catch (tinyformat::format_error& fmterr) {
 77          log_msg = "Error \"" + std::string{fmterr.what()} + "\" while formatting log message: " + fmt.fmt;
 78      }
 79      util::log::Log(util::log::Entry{
 80          .category = flag,
 81          .level = level,
 82          .should_ratelimit = should_ratelimit,
 83          .source_loc = std::move(source_loc),
 84          .message = std::move(log_msg)});
 85  }
 86  
 87  // Allow __func__ to be used in any context without warnings:
 88  // NOLINTNEXTLINE(bugprone-lambda-function-name)
 89  #define LogPrintLevel_(category, level, should_ratelimit, ...) LogPrintFormatInternal(SourceLocation{__func__}, category, level, should_ratelimit, __VA_ARGS__)
 90  
 91  // Log unconditionally. Uses basic rate limiting to mitigate disk filling attacks.
 92  // Be conservative when using functions that unconditionally log to debug.log!
 93  // It should not be the case that an inbound peer can fill up a user's storage
 94  // with debug.log entries.
 95  #define LogInfo(...) LogPrintLevel_(BCLog::LogFlags::ALL, BCLog::Level::Info, /*should_ratelimit=*/true, __VA_ARGS__)
 96  #define LogWarning(...) LogPrintLevel_(BCLog::LogFlags::ALL, BCLog::Level::Warning, /*should_ratelimit=*/true, __VA_ARGS__)
 97  #define LogError(...) LogPrintLevel_(BCLog::LogFlags::ALL, BCLog::Level::Error, /*should_ratelimit=*/true, __VA_ARGS__)
 98  
 99  // Use a macro instead of a function for conditional logging to prevent
100  // evaluating arguments when logging for the category is not enabled.
101  
102  // Log by prefixing the output with the passed category name and severity level. This logs conditionally if
103  // the category is allowed. No rate limiting is applied, because users specifying -debug are assumed to be
104  // developers or power users who are aware that -debug may cause excessive disk usage due to logging.
105  #define detail_LogIfCategoryAndLevelEnabled(category, level, ...)      \
106      do {                                                               \
107          if (util::log::ShouldLog((category), (level))) {               \
108              bool rate_limit{level >= BCLog::Level::Info};              \
109              Assume(!rate_limit); /*Only called with the levels below*/ \
110              LogPrintLevel_(category, level, rate_limit, __VA_ARGS__);  \
111          }                                                              \
112      } while (0)
113  
114  // Log conditionally, prefixing the output with the passed category name.
115  #define LogDebug(category, ...) detail_LogIfCategoryAndLevelEnabled(category, BCLog::Level::Debug, __VA_ARGS__)
116  #define LogTrace(category, ...) detail_LogIfCategoryAndLevelEnabled(category, BCLog::Level::Trace, __VA_ARGS__)
117  
118  #endif // BITCOIN_UTIL_LOG_H