platform_system_core/base/logging.cpp

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "base/logging.h"

#include <iostream>
#include <limits>
#include <mutex>
#include <sstream>
#include <string>
#include <vector>

#include "base/strings.h"
#include "cutils/threads.h"

// Headers for LogMessage::LogLine.
#ifdef __ANDROID__
#include <android/set_abort_message.h>
#include "cutils/log.h"
#else
#include <sys/types.h>
#include <unistd.h>
#endif

namespace android {
namespace base {

static std::mutex logging_lock;

static LogSeverity gMinimumLogSeverity = INFO;
static std::unique_ptr<std::string> gCmdLine;
static std::unique_ptr<std::string> gProgramInvocationName;
static std::unique_ptr<std::string> gProgramInvocationShortName;

const char* GetCmdLine() {
  return (gCmdLine.get() != nullptr) ? gCmdLine->c_str() : nullptr;
}

const char* ProgramInvocationName() {
  return (gProgramInvocationName.get() != nullptr)
             ? gProgramInvocationName->c_str()
             : "unknown";
}

const char* ProgramInvocationShortName() {
  return (gProgramInvocationShortName.get() != nullptr)
             ? gProgramInvocationShortName->c_str()
             : "unknown";
}

void InitLogging(char* argv[]) {
  if (gCmdLine.get() != nullptr) {
    return;
  }

  // Stash the command line for later use. We can use /proc/self/cmdline on
  // Linux to recover this, but we don't have that luxury on the Mac, and there
  // are a couple of argv[0] variants that are commonly used.
  if (argv != nullptr) {
    gCmdLine.reset(new std::string(argv[0]));
    for (size_t i = 1; argv[i] != nullptr; ++i) {
      gCmdLine->append(" ");
      gCmdLine->append(argv[i]);
    }
    gProgramInvocationName.reset(new std::string(argv[0]));
    const char* last_slash = strrchr(argv[0], '/');
    gProgramInvocationShortName.reset(
        new std::string((last_slash != nullptr) ? last_slash + 1 : argv[0]));
  } else {
    // TODO: fall back to /proc/self/cmdline when argv is NULL on Linux.
    gCmdLine.reset(new std::string("<unset>"));
  }
  const char* tags = getenv("ANDROID_LOG_TAGS");
  if (tags == nullptr) {
    return;
  }

  std::vector<std::string> specs = Split(tags, " ");
  for (size_t i = 0; i < specs.size(); ++i) {
    // "tag-pattern:[vdiwefs]"
    std::string spec(specs[i]);
    if (spec.size() == 3 && StartsWith(spec, "*:")) {
      switch (spec[2]) {
        case 'v':
          gMinimumLogSeverity = VERBOSE;
          continue;
        case 'd':
          gMinimumLogSeverity = DEBUG;
          continue;
        case 'i':
          gMinimumLogSeverity = INFO;
          continue;
        case 'w':
          gMinimumLogSeverity = WARNING;
          continue;
        case 'e':
          gMinimumLogSeverity = ERROR;
          continue;
        case 'f':
          gMinimumLogSeverity = FATAL;
          continue;
        // liblog will even suppress FATAL if you say 's' for silent, but that's
        // crazy!
        case 's':
          gMinimumLogSeverity = FATAL;
          continue;
      }
    }
    LOG(FATAL) << "unsupported '" << spec << "' in ANDROID_LOG_TAGS (" << tags
               << ")";
  }
}

// This indirection greatly reduces the stack impact of having lots of
// checks/logging in a function.
class LogMessageData {
 public:
  LogMessageData(const char* file, unsigned int line, LogSeverity severity,
                 int error)
      : file_(file), line_number_(line), severity_(severity), error_(error) {
    const char* last_slash = strrchr(file, '/');
    file = (last_slash == nullptr) ? file : last_slash + 1;
  }

  const char* GetFile() const {
    return file_;
  }

  unsigned int GetLineNumber() const {
    return line_number_;
  }

  LogSeverity GetSeverity() const {
    return severity_;
  }

  int GetError() const {
    return error_;
  }

  std::ostream& GetBuffer() {
    return buffer_;
  }

  std::string ToString() const {
    return buffer_.str();
  }

 private:
  std::ostringstream buffer_;
  const char* const file_;
  const unsigned int line_number_;
  const LogSeverity severity_;
  const int error_;

  DISALLOW_COPY_AND_ASSIGN(LogMessageData);
};

LogMessage::LogMessage(const char* file, unsigned int line,
                       LogSeverity severity, int error)
    : data_(new LogMessageData(file, line, severity, error)) {
}

LogMessage::~LogMessage() {
  if (data_->GetSeverity() < gMinimumLogSeverity) {
    return;  // No need to format something we're not going to output.
  }

  // Finish constructing the message.
  if (data_->GetError() != -1) {
    data_->GetBuffer() << ": " << strerror(data_->GetError());
  }
  std::string msg(data_->ToString());

  // Do the actual logging with the lock held.
  {
    std::lock_guard<std::mutex> lock(logging_lock);
    if (msg.find('\n') == std::string::npos) {
      LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetSeverity(),
              msg.c_str());
    } else {
      msg += '\n';
      size_t i = 0;
      while (i < msg.size()) {
        size_t nl = msg.find('\n', i);
        msg[nl] = '\0';
        LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetSeverity(),
                &msg[i]);
        i = nl + 1;
      }
    }
  }

  // Abort if necessary.
  if (data_->GetSeverity() == FATAL) {
#ifdef __ANDROID__
    android_set_abort_message(msg.c_str());
#endif
    abort();
  }
}

std::ostream& LogMessage::stream() {
  return data_->GetBuffer();
}

#ifdef __ANDROID__
static const android_LogPriority kLogSeverityToAndroidLogPriority[] = {
    ANDROID_LOG_VERBOSE, ANDROID_LOG_DEBUG, ANDROID_LOG_INFO,
    ANDROID_LOG_WARN,    ANDROID_LOG_ERROR, ANDROID_LOG_FATAL};
static_assert(arraysize(kLogSeverityToAndroidLogPriority) == FATAL + 1,
              "Mismatch in size of kLogSeverityToAndroidLogPriority and values "
              "in LogSeverity");
#endif

void LogMessage::LogLine(const char* file, unsigned int line,
                         LogSeverity log_severity, const char* message) {
#ifdef __ANDROID__
  const char* tag = ProgramInvocationShortName();
  int priority = kLogSeverityToAndroidLogPriority[log_severity];
  if (priority == ANDROID_LOG_FATAL) {
    LOG_PRI(priority, tag, "%s:%u] %s", file, line, message);
  } else {
    LOG_PRI(priority, tag, "%s", message);
  }
#else
  static const char* log_characters = "VDIWEF";
  CHECK_EQ(strlen(log_characters), FATAL + 1U);
  char severity = log_characters[log_severity];
  fprintf(stderr, "%s %c %5d %5d %s:%u] %s\n", ProgramInvocationShortName(),
          severity, getpid(), gettid(), file, line, message);
#endif
}

void LogMessage::LogLineLowStack(const char* file, unsigned int line,
                                 LogSeverity log_severity, const char* message) {
#ifdef __ANDROID__
  // Use android_writeLog() to avoid stack-based buffers used by
  // android_printLog().
  const char* tag = ProgramInvocationShortName();
  int priority = kLogSeverityToAndroidLogPriority[log_severity];
  char* buf = nullptr;
  size_t buf_size = 0u;
  if (priority == ANDROID_LOG_FATAL) {
    // Allocate buffer for snprintf(buf, buf_size, "%s:%u] %s", file, line,
    // message) below.  If allocation fails, fall back to printing only the
    // message.
    buf_size = strlen(file) + 1 /* ':' */ +
               std::numeric_limits<typeof(line)>::max_digits10 + 2 /* "] " */ +
               strlen(message) + 1 /* terminating 0 */;
    buf = reinterpret_cast<char*>(malloc(buf_size));
  }
  if (buf != nullptr) {
    snprintf(buf, buf_size, "%s:%u] %s", file, line, message);
    android_writeLog(priority, tag, buf);
    free(buf);
  } else {
    android_writeLog(priority, tag, message);
  }
#else
  static const char* log_characters = "VDIWEF";
  CHECK_EQ(strlen(log_characters), FATAL + 1U);

  const char* program_name = ProgramInvocationShortName();
  write(STDERR_FILENO, program_name, strlen(program_name));
  write(STDERR_FILENO, " ", 1);
  write(STDERR_FILENO, &log_characters[log_severity], 1);
  write(STDERR_FILENO, " ", 1);
  // TODO: pid and tid.
  write(STDERR_FILENO, file, strlen(file));
  // TODO: line.
  UNUSED(line);
  write(STDERR_FILENO, "] ", 2);
  write(STDERR_FILENO, message, strlen(message));
  write(STDERR_FILENO, "\n", 1);
#endif
}

ScopedLogSeverity::ScopedLogSeverity(LogSeverity level) {
  old_ = gMinimumLogSeverity;
  gMinimumLogSeverity = level;
}

ScopedLogSeverity::~ScopedLogSeverity() {
  gMinimumLogSeverity = old_;
}

}  // namespace base
}  // namespace android