// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <windows.h>
#include <shlwapi.h>

#include "base/command_line.h"
#include "base/compiler_specific.h"
#include "base/debug/trace_event.h"
#include "base/environment.h"
#include "base/file_version_info.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/rand_util.h"  // For PreRead experiment.
#include "base/sha1.h"  // For PreRead experiment.
#include "base/strings/string16.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/version.h"
#include "base/win/windows_version.h"
#include "chrome/app/chrome_breakpad_client.h"
#include "chrome/app/client_util.h"
#include "chrome/app/image_pre_reader_win.h"
#include "chrome/common/chrome_constants.h"
#include "chrome/common/chrome_result_codes.h"
#include "chrome/common/chrome_switches.h"
#include "chrome/common/env_vars.h"
#include "chrome/installer/util/google_update_constants.h"
#include "chrome/installer/util/google_update_settings.h"
#include "chrome/installer/util/install_util.h"
#include "chrome/installer/util/util_constants.h"
#include "components/crash/app/breakpad_client.h"
#include "components/crash/app/breakpad_win.h"
#include "components/metrics/client_info.h"
#include "content/public/app/startup_helper_win.h"
#include "sandbox/win/src/sandbox.h"

namespace {
// The entry point signature of chrome.dll.
typedef int (*DLL_MAIN)(HINSTANCE, sandbox::SandboxInterfaceInfo*);

typedef void (*RelaunchChromeBrowserWithNewCommandLineIfNeededFunc)();

base::LazyInstance<chrome::ChromeBreakpadClient>::Leaky
    g_chrome_breakpad_client = LAZY_INSTANCE_INITIALIZER;

// Returns true if the build date for this module precedes the expiry date
// for the pre-read experiment.
bool PreReadExperimentIsActive() {
  const int kPreReadExpiryYear = 2014;
  const int kPreReadExpiryMonth = 7;
  const int kPreReadExpiryDay = 1;
  const char kBuildTimeStr[] = __DATE__ " " __TIME__;

  // Get the timestamp of the build.
  base::Time build_time;
  bool result = base::Time::FromString(kBuildTimeStr, &build_time);
  DCHECK(result);

  // Get the timestamp at which the experiment expires.
  base::Time::Exploded exploded = {0};
  exploded.year = kPreReadExpiryYear;
  exploded.month = kPreReadExpiryMonth;
  exploded.day_of_month = kPreReadExpiryDay;
  base::Time expiration_time = base::Time::FromLocalExploded(exploded);

  // Return true if the build time predates the expiration time..
  return build_time < expiration_time;
}

// Get random unit values, i.e., in the range (0, 1), denoting a die-toss for
// being in an experiment population and experimental group thereof.
void GetPreReadPopulationAndGroup(double* population, double* group) {
  // By default we use the metrics id for the user as stable pseudo-random
  // input to a hash.
  scoped_ptr<metrics::ClientInfo> client_info =
      GoogleUpdateSettings::LoadMetricsClientInfo();

  // If this user has no metrics id, we fall back to a purely random value per
  // browser session.
  const size_t kLength = 16;
  std::string random_value(client_info ? client_info->client_id
                                       : base::RandBytesAsString(kLength));

  // To interpret the value as a random number we hash it and read the first 8
  // bytes of the hash as a unit-interval representing a die-toss for being in
  // the experiment population and the second 8 bytes as a die-toss for being
  // in various experiment groups.
  unsigned char sha1_hash[base::kSHA1Length];
  base::SHA1HashBytes(
      reinterpret_cast<const unsigned char*>(random_value.c_str()),
      random_value.size() * sizeof(random_value[0]),
      sha1_hash);
  COMPILE_ASSERT(2 * sizeof(uint64) < sizeof(sha1_hash), need_more_data);
  const uint64* random_bits = reinterpret_cast<uint64*>(&sha1_hash[0]);

  // Convert the bits into unit-intervals and return.
  *population = base::BitsToOpenEndedUnitInterval(random_bits[0]);
  *group = base::BitsToOpenEndedUnitInterval(random_bits[1]);
}

// Gets the amount of pre-read to use as well as the experiment group in which
// the user falls.
size_t InitPreReadPercentage() {
  // By default use the old behaviour: read 100%.
  const int kDefaultPercentage = 100;
  const char kDefaultFormatStr[] = "%d-pct-default";
  const char kControlFormatStr[] = "%d-pct-control";
  const char kGroupFormatStr[] = "%d-pct";

  COMPILE_ASSERT(kDefaultPercentage <= 100, default_percentage_too_large);
  COMPILE_ASSERT(kDefaultPercentage % 5 == 0, default_percentage_not_mult_5);

  // Roll the dice to determine if this user is in the experiment and if so,
  // in which experimental group.
  double population = 0.0;
  double group = 0.0;
  GetPreReadPopulationAndGroup(&population, &group);

  // We limit experiment populations to 1% of the Stable and 10% of each of
  // the other channels.
  const base::string16 channel(GoogleUpdateSettings::GetChromeChannel(
      GoogleUpdateSettings::IsSystemInstall()));
  double threshold = (channel == installer::kChromeChannelStable) ? 0.01 : 0.10;

  // If the experiment has expired use the default pre-read level. Otherwise,
  // those not in the experiment population also use the default pre-read level.
  size_t value = kDefaultPercentage;
  const char* format_str = kDefaultFormatStr;
  if (PreReadExperimentIsActive() && (population <= threshold)) {
    // We divide the experiment population into groups pre-reading at 5 percent
    // increments in the range [0, 100].
    value = static_cast<size_t>(group * 21.0) * 5;
    DCHECK_LE(value, 100u);
    DCHECK_EQ(0u, value % 5);
    format_str =
        (value == kDefaultPercentage) ? kControlFormatStr : kGroupFormatStr;
  }

  // Generate the group name corresponding to this percentage value.
  std::string group_name;
  base::SStringPrintf(&group_name, format_str, value);

  // Persist the group name to the environment so that it can be used for
  // reporting.
  scoped_ptr<base::Environment> env(base::Environment::Create());
  env->SetVar(chrome::kPreReadEnvironmentVariable, group_name);

  // Return the percentage value to be used.
  return value;
}

// Expects that |dir| has a trailing backslash. |dir| is modified so it
// contains the full path that was tried. Caller must check for the return
// value not being null to determine if this path contains a valid dll.
HMODULE LoadModuleWithDirectory(base::string16* dir,
                                const wchar_t* dll_name,
                                bool pre_read) {
  ::SetCurrentDirectoryW(dir->c_str());
  dir->append(dll_name);

  if (pre_read) {
#if !defined(WIN_DISABLE_PREREAD)
    // We pre-read the binary to warm the memory caches (fewer hard faults to
    // page parts of the binary in).
    const size_t kStepSize = 1024 * 1024;
    size_t percentage = InitPreReadPercentage();
    ImagePreReader::PartialPreReadImage(dir->c_str(), percentage, kStepSize);
#endif
  }

  return ::LoadLibraryExW(dir->c_str(), NULL,
                          LOAD_WITH_ALTERED_SEARCH_PATH);
}

void RecordDidRun(const base::string16& dll_path) {
  bool system_level = !InstallUtil::IsPerUserInstall(dll_path.c_str());
  GoogleUpdateSettings::UpdateDidRunState(true, system_level);
}

void ClearDidRun(const base::string16& dll_path) {
  bool system_level = !InstallUtil::IsPerUserInstall(dll_path.c_str());
  GoogleUpdateSettings::UpdateDidRunState(false, system_level);
}

bool InMetroMode() {
  return (wcsstr(
      ::GetCommandLineW(), L" -ServerName:DefaultBrowserServer") != NULL);
}

typedef int (*InitMetro)();

}  // namespace

base::string16 GetExecutablePath() {
  wchar_t path[MAX_PATH];
  ::GetModuleFileNameW(NULL, path, MAX_PATH);
  if (!::PathRemoveFileSpecW(path))
    return base::string16();
  base::string16 exe_path(path);
  return exe_path.append(1, L'\\');
}

base::string16 GetCurrentModuleVersion() {
  scoped_ptr<FileVersionInfo> file_version_info(
      FileVersionInfo::CreateFileVersionInfoForCurrentModule());
  if (file_version_info.get()) {
    base::string16 version_string(file_version_info->file_version());
    if (Version(base::UTF16ToASCII(version_string)).IsValid())
      return version_string;
  }
  return base::string16();
}

//=============================================================================

MainDllLoader::MainDllLoader()
  : dll_(NULL), metro_mode_(InMetroMode()) {
}

MainDllLoader::~MainDllLoader() {
}

// Loading chrome is an interesting affair. First we try loading from the
// current directory to support run-what-you-compile and other development
// scenarios.
// If that fails then we look at the version resource in the current
// module. This is the expected path for chrome.exe browser instances in an
// installed build.
HMODULE MainDllLoader::Load(base::string16* version,
                            base::string16* out_file) {
  const base::string16 executable_dir(GetExecutablePath());
  *out_file = executable_dir;

  const wchar_t* dll_name = metro_mode_ ?
      installer::kChromeMetroDll :
#if !defined(CHROME_MULTIPLE_DLL)
      installer::kChromeDll;
#else
      (process_type_ == "service")  || process_type_.empty() ?
          installer::kChromeDll :
          installer::kChromeChildDll;
#endif
  const bool pre_read = !metro_mode_;
  HMODULE dll = LoadModuleWithDirectory(out_file, dll_name, pre_read);
  if (!dll) {
    base::string16 version_string(GetCurrentModuleVersion());
    if (version_string.empty()) {
      LOG(ERROR) << "No valid Chrome version found";
      return NULL;
    }
    *out_file = executable_dir;
    *version = version_string;
    out_file->append(version_string).append(1, L'\\');
    dll = LoadModuleWithDirectory(out_file, dll_name, pre_read);
    if (!dll) {
      PLOG(ERROR) << "Failed to load Chrome DLL from " << *out_file;
      return NULL;
    }
  }

  DCHECK(dll);
  return dll;
}

// Launching is a matter of loading the right dll, setting the CHROME_VERSION
// environment variable and just calling the entry point. Derived classes can
// add custom code in the OnBeforeLaunch callback.
int MainDllLoader::Launch(HINSTANCE instance) {
  const CommandLine& cmd_line = *CommandLine::ForCurrentProcess();
  process_type_ = cmd_line.GetSwitchValueASCII(switches::kProcessType);

  base::string16 version;
  base::string16 file;

  if (metro_mode_) {
    HMODULE metro_dll = Load(&version, &file);
    if (!metro_dll)
      return chrome::RESULT_CODE_MISSING_DATA;

    InitMetro chrome_metro_main =
        reinterpret_cast<InitMetro>(::GetProcAddress(metro_dll, "InitMetro"));
    return chrome_metro_main();
  }

  // Initialize the sandbox services.
  sandbox::SandboxInterfaceInfo sandbox_info = {0};
  content::InitializeSandboxInfo(&sandbox_info);

  breakpad::SetBreakpadClient(g_chrome_breakpad_client.Pointer());
  bool exit_now = true;
  if (process_type_.empty()) {
    if (breakpad::ShowRestartDialogIfCrashed(&exit_now)) {
      // We restarted because of a previous crash. Ask user if we should
      // Relaunch. Only for the browser process. See crbug.com/132119.
      if (exit_now)
        return content::RESULT_CODE_NORMAL_EXIT;
    }
  }
  breakpad::InitCrashReporter(process_type_);

  dll_ = Load(&version, &file);
  if (!dll_)
    return chrome::RESULT_CODE_MISSING_DATA;

  scoped_ptr<base::Environment> env(base::Environment::Create());
  env->SetVar(chrome::kChromeVersionEnvVar, base::WideToUTF8(version));

  OnBeforeLaunch(file);
  DLL_MAIN chrome_main =
      reinterpret_cast<DLL_MAIN>(::GetProcAddress(dll_, "ChromeMain"));
  int rc = chrome_main(instance, &sandbox_info);
  return OnBeforeExit(rc, file);
}

void MainDllLoader::RelaunchChromeBrowserWithNewCommandLineIfNeeded() {
  if (!dll_)
    return;

  RelaunchChromeBrowserWithNewCommandLineIfNeededFunc relaunch_function =
      reinterpret_cast<RelaunchChromeBrowserWithNewCommandLineIfNeededFunc>(
          ::GetProcAddress(dll_,
                           "RelaunchChromeBrowserWithNewCommandLineIfNeeded"));
  if (!relaunch_function) {
    LOG(ERROR) << "Could not find exported function "
               << "RelaunchChromeBrowserWithNewCommandLineIfNeeded";
  } else {
    relaunch_function();
  }
}

//=============================================================================

class ChromeDllLoader : public MainDllLoader {
 protected:
  virtual void OnBeforeLaunch(const base::string16& dll_path) {
    RecordDidRun(dll_path);
  }

  virtual int OnBeforeExit(int return_code, const base::string16& dll_path) {
    // NORMAL_EXIT_CANCEL is used for experiments when the user cancels
    // so we need to reset the did_run signal so omaha does not count
    // this run as active usage.
    if (chrome::RESULT_CODE_NORMAL_EXIT_CANCEL == return_code) {
      ClearDidRun(dll_path);
    }
    return return_code;
  }
};

//=============================================================================

class ChromiumDllLoader : public MainDllLoader {
 protected:
  virtual void OnBeforeLaunch(const base::string16& dll_path) OVERRIDE {
  }
  virtual int OnBeforeExit(int return_code,
                           const base::string16& dll_path) OVERRIDE {
    return return_code;
  }
};

MainDllLoader* MakeMainDllLoader() {
#if defined(GOOGLE_CHROME_BUILD)
  return new ChromeDllLoader();
#else
  return new ChromiumDllLoader();
#endif
}