components/tracing/startup_tracing.cc

   1 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/tracing/startup_tracing.h"
   6
   7 #include "base/files/file_path.h"
   8 #include "base/files/file_util.h"
   9 #include "base/path_service.h"
  10 #include "base/trace_event/trace_event.h"
  11
  12 namespace tracing {
  13
  14 namespace {
  15
  16 // Maximum trace config file size that will be loaded, in bytes.
  17 const size_t kTraceConfigFileSizeLimit = 64 * 1024;
  18
  19 // Trace config file path:
  20 // - Android: /data/local/.config/chrome-trace-config.json
  21 // - POSIX other than Android: $HOME/.config/chrome-trace-config.json
  22 // - Win: %USERPROFILE%/.config/chrome-trace-config.json
  23 #if defined(OS_ANDROID)
  24 const base::FilePath::CharType kAndroidTraceConfigDir[] =
  25     FILE_PATH_LITERAL("/data/local");
  26 #endif
  27
  28 const base::FilePath::CharType kChromeConfigDir[] =
  29     FILE_PATH_LITERAL(".config");
  30 const base::FilePath::CharType kTraceConfigFileName[] =
  31     FILE_PATH_LITERAL("chrome-trace-config.json");
  32
  33 base::FilePath GetTraceConfigFilePath() {
  34 #if defined(OS_ANDROID)
  35   base::FilePath path(kAndroidTraceConfigDir);
  36 #elif defined(OS_POSIX) || defined(OS_WIN)
  37   base::FilePath path;
  38   PathService::Get(base::DIR_HOME, &path);
  39 #else
  40   base::FilePath path;
  41 #endif
  42   path = path.Append(kChromeConfigDir);
  43   path = path.Append(kTraceConfigFileName);
  44   return path;
  45 }
  46
  47 } // namespace
  48
  49 void EnableStartupTracingIfConfigFileExists() {
  50   base::FilePath trace_config_file_path = GetTraceConfigFilePath();
  51   if (!base::PathExists(trace_config_file_path))
  52     return;
  53
  54   std::string trace_config_str;
  55   if (!base::ReadFileToString(trace_config_file_path,
  56                               &trace_config_str,
  57                               kTraceConfigFileSizeLimit)) {
  58     return;
  59   }
  60
  61   base::trace_event::TraceConfig trace_config(trace_config_str);
  62   base::trace_event::TraceLog::GetInstance()->SetEnabled(
  63       trace_config, base::trace_event::TraceLog::RECORDING_MODE);
  64 }
  65
  66 }  // namespace tracing