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// 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/debug/trace_event.h"
#include "base/environment.h"
#include "base/file_util.h"
#include "base/file_version_info.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/string16.h"
#include "base/string_util.h"
#include "base/stringprintf.h"
#include "base/utf_string_conversions.h"
#include "base/version.h"
#include "base/win/registry.h"
#include "chrome/app/breakpad_win.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/installer/util/browser_distribution.h"
#include "chrome/installer/util/channel_info.h"
#include "chrome/installer/util/install_util.h"
#include "chrome/installer/util/google_update_constants.h"
#include "chrome/installer/util/google_update_settings.h"
#include "chrome/installer/util/util_constants.h"
namespace {
// The entry point signature of chrome.dll.
typedef int (*DLL_MAIN)(HINSTANCE, sandbox::SandboxInterfaceInfo*);
typedef void (*RelaunchChromeBrowserWithNewCommandLineIfNeededFunc)();
// Gets chrome version according to the load path. |exe_path| must be the
// backslash terminated directory of the current chrome.exe.
bool GetChromeVersion(const wchar_t* exe_dir, const wchar_t* key_path,
string16* version) {
HKEY reg_root = InstallUtil::IsPerUserInstall(exe_dir) ? HKEY_CURRENT_USER :
HKEY_LOCAL_MACHINE;
bool success = false;
base::win::RegKey key(reg_root, key_path, KEY_QUERY_VALUE);
if (key.Valid()) {
// If 'new_chrome.exe' is present it means chrome was auto-updated while
// running. We need to consult the opv value so we can load the old dll.
// TODO(cpu) : This is solving the same problem as the environment variable
// so one of them will eventually be deprecated.
string16 new_chrome_exe(exe_dir);
new_chrome_exe.append(installer::kChromeNewExe);
if (::PathFileExistsW(new_chrome_exe.c_str()) &&
key.ReadValue(google_update::kRegOldVersionField,
version) == ERROR_SUCCESS) {
success = true;
} else {
success = (key.ReadValue(google_update::kRegVersionField,
version) == ERROR_SUCCESS);
}
}
return success;
}
// Not generic, we only handle strings up to 128 chars.
bool EnvQueryStr(const wchar_t* key_name, string16* value) {
wchar_t out[128];
DWORD count = sizeof(out)/sizeof(out[0]);
DWORD rv = ::GetEnvironmentVariableW(key_name, out, count);
if ((rv == 0) || (rv >= count))
return false;
*value = out;
return true;
}
#if defined(OS_WIN)
#if defined(GOOGLE_CHROME_BUILD)
// These constants are used by the PreRead experiment.
const wchar_t kPreReadRegistryValue[] = L"PreReadExperimentGroup";
const int kPreReadExpiryYear = 2012;
const int kPreReadExpiryMonth = 7;
const int kPreReadExpiryDay = 1;
// These are control values.
const DWORD kPreReadExperimentFull = 100;
const DWORD kPreReadExperimentNone = 0;
// Modulate these for different experiments. These values should be a multiple
// of 5 between 0 and 100, exclusive.
const DWORD kPreReadExperimentA = 25;
const DWORD kPreReadExperimentB = 40;
void StaticAssertions() {
COMPILE_ASSERT(
kPreReadExperimentA <= 100, kPreReadExperimentA_exceeds_100);
COMPILE_ASSERT(
kPreReadExperimentA % 5 == 0, kPreReadExperimentA_is_not_a_multiple_of_5);
COMPILE_ASSERT(
kPreReadExperimentB <= 100, kPreReadExperimentB_exceeds_100);
COMPILE_ASSERT(
kPreReadExperimentB % 5 == 0, kPreReadExperimentB_is_not_a_multiple_of_5);
}
bool PreReadExperimentShouldRun() {
base::Time::Exploded exploded = { 0 };
exploded.year = kPreReadExpiryYear;
exploded.month = kPreReadExpiryMonth;
exploded.day_of_month = kPreReadExpiryDay;
base::Time expiration_time = base::Time::FromLocalExploded(exploded);
// Get the build time. This code is copied from
// base::FieldTrial::GetBuildTime. We can't use MetricsLogBase::GetBuildTime
// because that's in seconds since Unix epoch, which base::Time can't use.
base::Time build_time;
const char* kDateTime = __DATE__ " " __TIME__;
bool result = base::Time::FromString(kDateTime, &build_time);
DCHECK(result);
// If the experiment is expired, don't run it.
return (build_time <= expiration_time);
}
// For channels with small populations we just divide the population evenly
// across the 4 buckets.
DWORD GetSmallPopulationPreReadBucket(double rand_unit) {
DCHECK_GE(rand_unit, 0.0);
DCHECK_LT(rand_unit, 1.0);
if (rand_unit < 0.25 || rand_unit > 1.0)
return kPreReadExperimentFull; // The default pre-read amount.
if (rand_unit < 0.50)
return kPreReadExperimentA;
if (rand_unit < 0.75)
return kPreReadExperimentB;
return kPreReadExperimentNone;
}
// For channels with large populations, we allocate a small percentage of the
// population to each of the experimental buckets, and the rest to the current
// default pre-read behaviour
DWORD GetLargePopulationPreReadBucket(double rand_unit) {
DCHECK_GE(rand_unit, 0.0);
DCHECK_LT(rand_unit, 1.0);
if (rand_unit < 0.97 || rand_unit > 1.0)
return kPreReadExperimentFull; // The default pre-read amount.
if (rand_unit < 0.98)
return kPreReadExperimentA;
if (rand_unit < 0.99)
return kPreReadExperimentB;
return kPreReadExperimentNone;
}
// Returns true and the |pre_read_percentage| IFF the experiment should run.
// Otherwise, returns false and |pre_read_percentage| is not modified.
bool GetPreReadExperimentGroup(DWORD* pre_read_percentage) {
DCHECK(pre_read_percentage != NULL);
// Check if the experiment has expired.
if (!PreReadExperimentShouldRun())
return false;
// Get the MetricsId of the installation. This is only set if the user has
// opted in to reporting. Doing things this way ensures that we only enable
// the experiment if its results are actually going to be reported.
string16 metrics_id;
if (!GoogleUpdateSettings::GetMetricsId(&metrics_id) || metrics_id.empty())
return false;
// We use the same technique as FieldTrial::HashClientId.
unsigned char sha1_hash[base::kSHA1Length];
base::SHA1HashBytes(
reinterpret_cast<const unsigned char*>(metrics_id.c_str()),
metrics_id.size() * sizeof(metrics_id[0]),
sha1_hash);
COMPILE_ASSERT(sizeof(uint64) < sizeof(sha1_hash), need_more_data);
uint64* bits = reinterpret_cast<uint64*>(&sha1_hash[0]);
double rand_unit = base::BitsToOpenEndedUnitInterval(*bits);
// We carve up the bucket sizes based on the population of the channel.
const string16 channel(
GoogleUpdateSettings::GetChromeChannel(
GoogleUpdateSettings::IsSystemInstall()));
// For our purposes, Stable has a large population, everything else is small.
*pre_read_percentage = (channel == installer::kChromeChannelStable ?
GetLargePopulationPreReadBucket(rand_unit) :
GetSmallPopulationPreReadBucket(rand_unit));
return true;
}
#endif // if defined(GOOGLE_CHROME_BUILD)
#endif // if defined(OS_WIN)
// 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 LoadChromeWithDirectory(string16* dir) {
::SetCurrentDirectoryW(dir->c_str());
const CommandLine& cmd_line = *CommandLine::ForCurrentProcess();
dir->append(installer::kChromeDll);
#ifndef WIN_DISABLE_PREREAD
#ifdef NDEBUG
// Experimental pre-reading optimization
// The idea is to pre-read a significant portion of chrome.dll in advance
// so that subsequent hard page faults are avoided.
//
// Pre-read may be disabled at compile time by defining WIN_DISABLE_PREREAD,
// but by default it is enabled in release builds. The ability to disable it
// is useful for evaluating competing optimization techniques.
if (!cmd_line.HasSwitch(switches::kProcessType)) {
// The kernel brings in 8 pages for the code section at a time and 4 pages
// for other sections. We can skip over these pages to avoid a soft page
// fault which may not occur during code execution. However skipping 4K at
// a time still has better performance over 32K and 16K according to data.
// TODO(ananta): Investigate this and tune.
const size_t kStepSize = 4 * 1024;
// We hypothesize that pre-reading only the bytes actually touched during
// startup should improve startup time. The Syzygy toolchain attempts to
// optimize the binary layout of chrome.dll, rearranging the code and data
// blocks such that temporally related blocks (i.e., code and data used in
// startup, browser, renderer, etc) are grouped together, and that blocks
// used early in the process lifecycle occur earlier in their sections.
DWORD pre_read_percentage = 100;
DWORD pre_read_step_size = kStepSize;
bool is_eligible_for_experiment = true;
// TODO(chrisha): This path should not be ChromeFrame specific, and it
// should not be hard-coded with 'Google' in the path. Rather, it should
// use the product name.
base::win::RegKey key(HKEY_CURRENT_USER,
L"Software\\Google\\ChromeFrame",
KEY_QUERY_VALUE);
// Check if there are any pre-read settings in the registry. If so, then
// the pre-read settings have been forcibly set and this instance is not
// eligible for the pre-read experiment.
if (key.Valid()) {
DWORD value = 0;
if (key.ReadValueDW(L"PreRead", &value) == ERROR_SUCCESS) {
is_eligible_for_experiment = false;
pre_read_percentage = (value != 0) ? 100 : 0;
}
if (key.ReadValueDW(L"PreReadPercentage", &value) == ERROR_SUCCESS) {
is_eligible_for_experiment = false;
pre_read_percentage = value;
}
if (key.ReadValueDW(L"PreReadStepSize", &value) == ERROR_SUCCESS) {
is_eligible_for_experiment = false;
pre_read_step_size = value;
}
key.Close();
}
#if defined(OS_WIN)
#if defined(GOOGLE_CHROME_BUILD)
// The PreRead experiment is unable to use the standard FieldTrial
// mechanism as pre-reading happens in chrome.exe prior to loading
// chrome.dll. As such, we use a custom approach. If the experiment is
// running (not expired) then we look to the registry for the BreakPad/UMA
// metricsid. We use this to seed a random unit, and select a bucket
// (percentage to pre-read) for the experiment. The selected bucket is
// communicated to chrome.dll via an environment variable, which alerts
// chrome.dll that the experiment is running, causing it to report
// sub-histogram results.
//
// If we've read pre-read settings from the registry, then someone has
// specifically forced their pre-read options and is not participating in
// the experiment.
//
// If the experiment is running, indicate it to chrome.dll via an
// environment variable that contains the percentage of chrome that
// was pre-read. Allowable values are all multiples of 5 between
// 0 and 100, inclusive.
if (is_eligible_for_experiment &&
GetPreReadExperimentGroup(&pre_read_percentage)) {
DCHECK_LE(pre_read_percentage, 100U);
DCHECK_EQ(pre_read_percentage % 5, 0U);
scoped_ptr<base::Environment> env(base::Environment::Create());
env->SetVar(chrome::kPreReadEnvironmentVariable,
base::StringPrintf("%d", pre_read_percentage));
}
#endif // if defined(GOOGLE_CHROME_BUILD)
#endif // if defined(OS_WIN)
// Clamp the DWORD percentage to fit into a uint8 that's <= 100.
pre_read_percentage = std::min(pre_read_percentage, 100UL);
// Perform the full or partial pre-read.
TRACE_EVENT_BEGIN_ETW("PreReadImage", 0, "");
ImagePreReader::PartialPreReadImage(dir->c_str(),
static_cast<uint8>(pre_read_percentage),
pre_read_step_size);
TRACE_EVENT_END_ETW("PreReadImage", 0, "");
}
#endif // NDEBUG
#endif // WIN_DISABLE_PREREAD
return ::LoadLibraryExW(dir->c_str(), NULL,
LOAD_WITH_ALTERED_SEARCH_PATH);
}
void RecordDidRun(const string16& dll_path) {
bool system_level = !InstallUtil::IsPerUserInstall(dll_path.c_str());
GoogleUpdateSettings::UpdateDidRunState(true, system_level);
}
void ClearDidRun(const string16& dll_path) {
bool system_level = !InstallUtil::IsPerUserInstall(dll_path.c_str());
GoogleUpdateSettings::UpdateDidRunState(false, system_level);
}
} // namespace
string16 GetExecutablePath() {
wchar_t path[MAX_PATH];
::GetModuleFileNameW(NULL, path, MAX_PATH);
if (!::PathRemoveFileSpecW(path))
return string16();
string16 exe_path(path);
return exe_path.append(1, L'\\');
}
//=============================================================================
MainDllLoader::MainDllLoader() : dll_(NULL) {
}
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 --chrome-version command line flag followed
// by the 'CHROME_VERSION' env variable to determine if we should stick with an
// older dll version even if a new one is available to support upgrade-in-place
// scenarios.
// If that fails then finally we look at the registry which should point us
// to the latest version. This is the expected path for the first chrome.exe
// browser instance in an installed build.
HMODULE MainDllLoader::Load(string16* out_version, string16* out_file) {
const string16 dir(GetExecutablePath());
*out_file = dir;
HMODULE dll = LoadChromeWithDirectory(out_file);
if (dll)
return dll;
string16 version_string;
Version version;
const CommandLine& cmd_line = *CommandLine::ForCurrentProcess();
if (cmd_line.HasSwitch(switches::kChromeVersion)) {
version_string = cmd_line.GetSwitchValueNative(switches::kChromeVersion);
version = Version(WideToASCII(version_string));
if (!version.IsValid()) {
// If a bogus command line flag was given, then abort.
LOG(ERROR) << "Invalid command line version: " << version_string;
return NULL;
}
}
// If no version on the command line, then look at the version resource in
// the current module and try loading that.
if (!version.IsValid()) {
scoped_ptr<FileVersionInfo> file_version_info(
FileVersionInfo::CreateFileVersionInfoForCurrentModule());
if (file_version_info.get()) {
version_string = file_version_info->file_version();
version = Version(WideToASCII(version_string));
}
}
// TODO(robertshield): in theory, these next two checks (env and registry)
// should never be needed. Remove them when I become 100% certain this is
// also true in practice.
// If no version in the current module, then look in the environment.
if (!version.IsValid()) {
if (EnvQueryStr(ASCIIToWide(chrome::kChromeVersionEnvVar).c_str(),
&version_string)) {
version = Version(WideToASCII(version_string));
LOG_IF(ERROR, !version.IsValid()) << "Invalid environment version: "
<< version_string;
}
}
// If no version in the environment, then look in the registry.
if (!version.IsValid()) {
version_string = GetVersion();
if (version_string.empty()) {
LOG(ERROR) << "Could not get Chrome DLL version.";
return NULL;
}
}
*out_file = dir;
*out_version = version_string;
out_file->append(*out_version).append(1, L'\\');
dll = LoadChromeWithDirectory(out_file);
if (!dll) {
LOG(ERROR) << "Failed to load Chrome DLL from " << *out_file;
return NULL;
}
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,
sandbox::SandboxInterfaceInfo* sbox_info) {
string16 version;
string16 file;
dll_ = Load(&version, &file);
if (!dll_)
return chrome::RESULT_CODE_MISSING_DATA;
scoped_ptr<base::Environment> env(base::Environment::Create());
env->SetVar(chrome::kChromeVersionEnvVar, WideToUTF8(version));
InitCrashReporter();
OnBeforeLaunch(file);
DLL_MAIN entry_point =
reinterpret_cast<DLL_MAIN>(::GetProcAddress(dll_, "ChromeMain"));
if (!entry_point)
return chrome::RESULT_CODE_BAD_PROCESS_TYPE;
int rc = entry_point(instance, sbox_info);
return OnBeforeExit(rc, file);
}
string16 MainDllLoader::GetVersion() {
string16 reg_path(GetRegistryPath());
string16 version_string;
string16 dir(GetExecutablePath());
if (!GetChromeVersion(dir.c_str(), reg_path.c_str(), &version_string))
return string16();
return version_string;
}
void MainDllLoader::RelaunchChromeBrowserWithNewCommandLineIfNeeded() {
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 {
public:
virtual string16 GetRegistryPath() {
string16 key(google_update::kRegPathClients);
BrowserDistribution* dist = BrowserDistribution::GetDistribution();
key.append(L"\\").append(dist->GetAppGuid());
return key;
}
virtual void OnBeforeLaunch(const string16& dll_path) {
RecordDidRun(dll_path);
}
virtual int OnBeforeExit(int return_code, const 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 {
public:
virtual string16 GetRegistryPath() {
BrowserDistribution* dist = BrowserDistribution::GetDistribution();
return dist->GetVersionKey();
}
};
MainDllLoader* MakeMainDllLoader() {
#if defined(GOOGLE_CHROME_BUILD)
return new ChromeDllLoader();
#else
return new ChromiumDllLoader();
#endif
}