common/log.cc

/*
 * Copyright 2024 The ChromiumOS Authors
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "common/log.h"

#include <errno.h>
#include <syslog.h>

#include <string>

#include "absl/strings/str_format.h"

namespace tflite::cros::log_impl {

namespace {

const char* GetProgramName() {
  // This is defined in <errno.h>.
  const char* name = program_invocation_short_name;
  return name != nullptr ? name : "";
}

int GetSyslogLevel(const absl::LogEntry& entry) {
  if (entry.verbosity() != absl::LogEntry::kNoVerbosityLevel) {
    return LOG_DEBUG;
  }

  switch (entry.log_severity()) {
    case absl::LogSeverity::kInfo:
      return LOG_INFO;
    case absl::LogSeverity::kWarning:
      return LOG_WARNING;
    case absl::LogSeverity::kError:
      return LOG_ERR;
    case absl::LogSeverity::kFatal:
      return LOG_CRIT;
  }

  // Safe fallback. Should not happen normally.
  return LOG_DEBUG;
}

}  // namespace

SyslogStderrSink* SyslogStderrSink::GetInstance() {
  // Leaky singleton.
  using Self = SyslogStderrSink;
  alignas(Self) static uint8_t storage[sizeof(Self)];
  static Self* instance = new (storage) Self();
  return instance;
}

void SyslogStderrSink::Send(const absl::LogEntry& entry) {
  syslog(GetSyslogLevel(entry), "%s",
         entry.text_message_with_prefix_and_newline_c_str());

  std::string timestamp = absl::FormatTime(
      "%Y-%m-%d%ET%H:%M:%E6SZ", entry.timestamp(), absl::UTCTimeZone());
  const char* severity = absl::LogSeverityName(entry.log_severity());

  // A syslog compatible format used on ChromeOS. Reference:
  // https://source.chromium.org/chromium/chromium/src/+/main:base/logging_chromeos.cc
  //
  // We don't provide control knobs for simplicity. The format looks like:
  // <timestamp> <severity> <program>[<pid>:<tid>]: [<file>(<line>)] <message>
  //
  // TODO(shik): Only print thread id when it's different from the process id.
  // TODO(shik): Only log to stderr if stdin is a tty.
  std::string body = absl::StrFormat(
      "%v %s %s[%d:%d]: [%v(%d)] %v", timestamp, severity, GetProgramName(),
      getpid(), entry.tid(), entry.source_basename(), entry.source_line(),
      entry.text_message_with_newline());
  fwrite(body.data(), body.size(), 1, stderr);

  // TODO(shik): Print stacktrace if available.
}

}  // namespace tflite::cros::log_impl