base/fuchsia/scoped_fx_logger.cc

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/fuchsia/scoped_fx_logger.h"

#include <lib/component/incoming/cpp/protocol.h>
#include <lib/fdio/directory.h>
#include <stdio.h>

#include <string_view>

#include "base/command_line.h"
#include "base/files/file_path.h"
#include "base/fuchsia/fuchsia_component_connect.h"
#include "base/fuchsia/fuchsia_logging.h"
#include "base/process/process.h"
#include "base/threading/platform_thread.h"

namespace base {

namespace {

inline FuchsiaLogSeverity LogSeverityToFuchsiaLogSeverity(
    logging::LogSeverity severity) {
  switch (severity) {
    case logging::LOGGING_INFO:
      return FUCHSIA_LOG_INFO;
    case logging::LOGGING_WARNING:
      return FUCHSIA_LOG_WARNING;
    case logging::LOGGING_ERROR:
      return FUCHSIA_LOG_ERROR;
    case logging::LOGGING_FATAL:
      // Don't use FX_LOG_FATAL, otherwise fx_logger_log() will abort().
      return FUCHSIA_LOG_ERROR;
  }
  if (severity > -3) {
    // LOGGING_VERBOSE levels 1 and 2.
    return FUCHSIA_LOG_DEBUG;
  }
  // LOGGING_VERBOSE levels 3 and higher, or incorrect levels.
  return FUCHSIA_LOG_TRACE;
}

}  // namespace

ScopedFxLogger::ScopedFxLogger() = default;
ScopedFxLogger::~ScopedFxLogger() = default;

ScopedFxLogger::ScopedFxLogger(ScopedFxLogger&& other) = default;
ScopedFxLogger& ScopedFxLogger::operator=(ScopedFxLogger&& other) = default;

// static
ScopedFxLogger ScopedFxLogger::CreateForProcess(
    std::vector<std::string_view> tags) {
  // CHECK()ing or LOG()ing inside this function is safe, since it is only
  // called to initialize logging, not during individual logging operations.

  auto log_sink_client_end = component::Connect<fuchsia_logger::LogSink>();
  if (log_sink_client_end.is_error()) {
    LOG(ERROR) << FidlConnectionErrorMessage(log_sink_client_end);
    return {};
  }

  // Rather than relying on automatic LogSink attribution via COMPONENT_NAME,
  // prepend a tag based on the calling process' name.  COMPONENT_NAME may be
  // mis-attributed, in some Component configurations, to a parent or caller
  // component, from which the process' LogSink service is routed.
  std::string program_name = base::CommandLine::ForCurrentProcess()
                                 ->GetProgram()
                                 .BaseName()
                                 .AsUTF8Unsafe();
  tags.insert(tags.begin(), program_name);

  return CreateFromLogSink(std::move(log_sink_client_end.value()),
                           std::move(tags));
}

// static
ScopedFxLogger ScopedFxLogger::CreateFromLogSink(
    fidl::ClientEnd<fuchsia_logger::LogSink> log_sink_client_end,
    std::vector<std::string_view> tags) {
  // CHECK()ing or LOG()ing inside this function is safe, since it is only
  // called to initialize logging, not during individual logging operations.

  // Attempts to create a kernel socket object should never fail.
  zx::socket local, remote;
  zx_status_t socket_status =
      zx::socket::create(ZX_SOCKET_DATAGRAM, &local, &remote);
  ZX_CHECK(socket_status == ZX_OK, socket_status)
      << "zx_socket_create() failed";

  // ConnectStructured() may fail if e.g. the LogSink has disconnected already.
  fidl::SyncClient log_sink(std::move(log_sink_client_end));
  auto connect_structured_result =
      log_sink->ConnectStructured(std::move(remote));
  if (connect_structured_result.is_error()) {
    ZX_LOG(ERROR, connect_structured_result.error_value().status())
        << "ConnectStructured() failed";
    return {};
  }

  return ScopedFxLogger(std::move(tags), std::move(local));
}

void ScopedFxLogger::LogMessage(std::string_view file,
                                uint32_t line_number,
                                std::string_view msg,
                                logging::LogSeverity severity) {
  if (!socket_.is_valid()) {
    return;
  }

  auto fuchsia_severity = LogSeverityToFuchsiaLogSeverity(severity);

  // It is not safe to use e.g. CHECK() or LOG() macros here, since those
  // may result in reentrancy if this instance is used for routing process-
  // global logs to the system logger.

  fuchsia_syslog::LogBuffer buffer;
  buffer.BeginRecord(fuchsia_severity,
                     cpp17::string_view(file.data(), file.size()), line_number,
                     cpp17::string_view(msg.data(), msg.size()),
                     socket_.borrow(), 0, base::Process::Current().Pid(),
                     base::PlatformThread::CurrentId().raw());
  for (const auto& tag : tags_) {
    buffer.WriteKeyValue("tag", tag);
  }
  if (!buffer.FlushRecord()) {
    fprintf(stderr, "fuchsia_syslog.LogBuffer.FlushRecord() failed\n");
  }
}

ScopedFxLogger::ScopedFxLogger(std::vector<std::string_view> tags,
                               zx::socket socket)
    : tags_(tags.begin(), tags.end()), socket_(std::move(socket)) {}

}  // namespace base