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      1 // Copyright (c) 2012 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 <windows.h>
      6 #include <shlwapi.h>
      7 
      8 #include "base/command_line.h"
      9 #include "base/debug/trace_event.h"
     10 #include "base/environment.h"
     11 #include "base/file_version_info.h"
     12 #include "base/logging.h"
     13 #include "base/memory/scoped_ptr.h"
     14 #include "base/rand_util.h"  // For PreRead experiment.
     15 #include "base/sha1.h"  // For PreRead experiment.
     16 #include "base/strings/string16.h"
     17 #include "base/strings/string_util.h"
     18 #include "base/strings/stringprintf.h"
     19 #include "base/strings/utf_string_conversions.h"
     20 #include "base/version.h"
     21 #include "base/win/windows_version.h"
     22 #include "chrome/app/client_util.h"
     23 #include "chrome/app/image_pre_reader_win.h"
     24 #include "chrome/common/chrome_constants.h"
     25 #include "chrome/common/chrome_result_codes.h"
     26 #include "chrome/common/chrome_switches.h"
     27 #include "chrome/common/env_vars.h"
     28 #include "chrome/installer/util/browser_distribution.h"
     29 #include "chrome/installer/util/channel_info.h"
     30 #include "chrome/installer/util/google_update_constants.h"
     31 #include "chrome/installer/util/google_update_settings.h"
     32 #include "chrome/installer/util/install_util.h"
     33 #include "chrome/installer/util/util_constants.h"
     34 #include "components/breakpad/app/breakpad_win.h"
     35 
     36 namespace {
     37 // The entry point signature of chrome.dll.
     38 typedef int (*DLL_MAIN)(HINSTANCE, sandbox::SandboxInterfaceInfo*);
     39 
     40 typedef void (*RelaunchChromeBrowserWithNewCommandLineIfNeededFunc)();
     41 
     42 // Returns true if the build date for this module precedes the expiry date
     43 // for the pre-read experiment.
     44 bool PreReadExperimentIsActive() {
     45   const int kPreReadExpiryYear = 2014;
     46   const int kPreReadExpiryMonth = 7;
     47   const int kPreReadExpiryDay = 1;
     48   const char kBuildTimeStr[] = __DATE__ " " __TIME__;
     49 
     50   // Get the timestamp of the build.
     51   base::Time build_time;
     52   bool result = base::Time::FromString(kBuildTimeStr, &build_time);
     53   DCHECK(result);
     54 
     55   // Get the timestamp at which the experiment expires.
     56   base::Time::Exploded exploded = {0};
     57   exploded.year = kPreReadExpiryYear;
     58   exploded.month = kPreReadExpiryMonth;
     59   exploded.day_of_month = kPreReadExpiryDay;
     60   base::Time expiration_time = base::Time::FromLocalExploded(exploded);
     61 
     62   // Return true if the build time predates the expiration time..
     63   return build_time < expiration_time;
     64 }
     65 
     66 // Get random unit values, i.e., in the range (0, 1), denoting a die-toss for
     67 // being in an experiment population and experimental group thereof.
     68 void GetPreReadPopulationAndGroup(double* population, double* group) {
     69   // By default we use the metrics id for the user as stable pseudo-random
     70   // input to a hash.
     71   std::string metrics_id;
     72   GoogleUpdateSettings::GetMetricsId(&metrics_id);
     73 
     74   // If this user has not metrics id, we fall back to a purely random value
     75   // per browser session.
     76   const size_t kLength = 16;
     77   std::string random_value(metrics_id.empty() ? base::RandBytesAsString(kLength)
     78                                               : metrics_id);
     79 
     80   // To interpret the value as a random number we hash it and read the first 8
     81   // bytes of the hash as a unit-interval representing a die-toss for being in
     82   // the experiment population and the second 8 bytes as a die-toss for being
     83   // in various experiment groups.
     84   unsigned char sha1_hash[base::kSHA1Length];
     85   base::SHA1HashBytes(
     86       reinterpret_cast<const unsigned char*>(random_value.c_str()),
     87       random_value.size() * sizeof(random_value[0]),
     88       sha1_hash);
     89   COMPILE_ASSERT(2 * sizeof(uint64) < sizeof(sha1_hash), need_more_data);
     90   const uint64* random_bits = reinterpret_cast<uint64*>(&sha1_hash[0]);
     91 
     92   // Convert the bits into unit-intervals and return.
     93   *population = base::BitsToOpenEndedUnitInterval(random_bits[0]);
     94   *group = base::BitsToOpenEndedUnitInterval(random_bits[1]);
     95 }
     96 
     97 // Gets the amount of pre-read to use as well as the experiment group in which
     98 // the user falls.
     99 size_t InitPreReadPercentage() {
    100   // By default use the old behaviour: read 100%.
    101   const int kDefaultPercentage = 100;
    102   const char kDefaultFormatStr[] = "%d-pct-default";
    103   const char kControlFormatStr[] = "%d-pct-control";
    104   const char kGroupFormatStr[] = "%d-pct";
    105 
    106   COMPILE_ASSERT(kDefaultPercentage <= 100, default_percentage_too_large);
    107   COMPILE_ASSERT(kDefaultPercentage % 5 == 0, default_percentage_not_mult_5);
    108 
    109   // Roll the dice to determine if this user is in the experiment and if so,
    110   // in which experimental group.
    111   double population = 0.0;
    112   double group = 0.0;
    113   GetPreReadPopulationAndGroup(&population, &group);
    114 
    115   // We limit experiment populations to 1% of the Stable and 10% of each of
    116   // the other channels.
    117   const string16 channel(GoogleUpdateSettings::GetChromeChannel(
    118       GoogleUpdateSettings::IsSystemInstall()));
    119   double threshold = (channel == installer::kChromeChannelStable) ? 0.01 : 0.10;
    120 
    121   // If the experiment has expired use the default pre-read level. Otherwise,
    122   // those not in the experiment population also use the default pre-read level.
    123   size_t value = kDefaultPercentage;
    124   const char* format_str = kDefaultFormatStr;
    125   if (PreReadExperimentIsActive() && (population <= threshold)) {
    126     // We divide the experiment population into groups pre-reading at 5 percent
    127     // increments in the range [0, 100].
    128     value = static_cast<size_t>(group * 21.0) * 5;
    129     DCHECK_LE(value, 100u);
    130     DCHECK_EQ(0u, value % 5);
    131     format_str =
    132         (value == kDefaultPercentage) ? kControlFormatStr : kGroupFormatStr;
    133   }
    134 
    135   // Generate the group name corresponding to this percentage value.
    136   std::string group_name;
    137   base::SStringPrintf(&group_name, format_str, value);
    138 
    139   // Persist the group name to the environment so that it can be used for
    140   // reporting.
    141   scoped_ptr<base::Environment> env(base::Environment::Create());
    142   env->SetVar(chrome::kPreReadEnvironmentVariable, group_name);
    143 
    144   // Return the percentage value to be used.
    145   return value;
    146 }
    147 
    148 // Expects that |dir| has a trailing backslash. |dir| is modified so it
    149 // contains the full path that was tried. Caller must check for the return
    150 // value not being null to determine if this path contains a valid dll.
    151 HMODULE LoadChromeWithDirectory(string16* dir) {
    152   ::SetCurrentDirectoryW(dir->c_str());
    153   const CommandLine& cmd_line = *CommandLine::ForCurrentProcess();
    154 #if !defined(CHROME_MULTIPLE_DLL)
    155   const wchar_t* dll_name = installer::kChromeDll;
    156 #else
    157   const wchar_t* dll_name =
    158       cmd_line.HasSwitch(switches::kProcessType) &&
    159               cmd_line.GetSwitchValueASCII(switches::kProcessType) != "service"
    160           ? installer::kChromeChildDll
    161           : installer::kChromeDll;
    162 #endif
    163   dir->append(dll_name);
    164 
    165 #if !defined(WIN_DISABLE_PREREAD)
    166   // We pre-read the binary to warm the memory caches (fewer hard faults to
    167   // page parts of the binary in).
    168   if (!cmd_line.HasSwitch(switches::kProcessType)) {
    169     const size_t kStepSize = 1024 * 1024;
    170     size_t percentage = InitPreReadPercentage();
    171     ImagePreReader::PartialPreReadImage(dir->c_str(), percentage, kStepSize);
    172   }
    173 #endif
    174 
    175   return ::LoadLibraryExW(dir->c_str(), NULL,
    176                           LOAD_WITH_ALTERED_SEARCH_PATH);
    177 }
    178 
    179 void RecordDidRun(const string16& dll_path) {
    180   bool system_level = !InstallUtil::IsPerUserInstall(dll_path.c_str());
    181   GoogleUpdateSettings::UpdateDidRunState(true, system_level);
    182 }
    183 
    184 void ClearDidRun(const string16& dll_path) {
    185   bool system_level = !InstallUtil::IsPerUserInstall(dll_path.c_str());
    186   GoogleUpdateSettings::UpdateDidRunState(false, system_level);
    187 }
    188 
    189 }  // namespace
    190 
    191 string16 GetExecutablePath() {
    192   wchar_t path[MAX_PATH];
    193   ::GetModuleFileNameW(NULL, path, MAX_PATH);
    194   if (!::PathRemoveFileSpecW(path))
    195     return string16();
    196   string16 exe_path(path);
    197   return exe_path.append(1, L'\\');
    198 }
    199 
    200 string16 GetCurrentModuleVersion() {
    201   scoped_ptr<FileVersionInfo> file_version_info(
    202       FileVersionInfo::CreateFileVersionInfoForCurrentModule());
    203   if (file_version_info.get()) {
    204     string16 version_string(file_version_info->file_version());
    205     if (Version(WideToASCII(version_string)).IsValid())
    206       return version_string;
    207   }
    208   return string16();
    209 }
    210 
    211 //=============================================================================
    212 
    213 MainDllLoader::MainDllLoader() : dll_(NULL) {
    214 }
    215 
    216 MainDllLoader::~MainDllLoader() {
    217 }
    218 
    219 // Loading chrome is an interesting affair. First we try loading from the
    220 // current directory to support run-what-you-compile and other development
    221 // scenarios.
    222 // If that fails then we look at the --chrome-version command line flag to
    223 // determine if we should stick with an older dll version even if a new one is
    224 // available to support upgrade-in-place scenarios.
    225 // If that fails then finally we look at the version resource in the current
    226 // module. This is the expected path for chrome.exe browser instances in an
    227 // installed build.
    228 HMODULE MainDllLoader::Load(string16* out_version, string16* out_file) {
    229   const CommandLine& cmd_line = *CommandLine::ForCurrentProcess();
    230   const string16 dir(GetExecutablePath());
    231   *out_file = dir;
    232   HMODULE dll = LoadChromeWithDirectory(out_file);
    233   if (!dll) {
    234     // Loading from same directory (for developers) failed.
    235     string16 version_string;
    236     if (cmd_line.HasSwitch(switches::kChromeVersion)) {
    237       // This is used to support Chrome Frame, see http://crbug.com/88589.
    238       version_string = cmd_line.GetSwitchValueNative(switches::kChromeVersion);
    239 
    240       if (!Version(WideToASCII(version_string)).IsValid()) {
    241         // If a bogus command line flag was given, then abort.
    242         LOG(ERROR) << "Invalid command line version: " << version_string;
    243         return NULL;
    244       }
    245     }
    246 
    247     // If no version on the command line, then look at the version resource in
    248     // the current module and try loading that.
    249     if (version_string.empty())
    250       version_string = GetCurrentModuleVersion();
    251 
    252     if (version_string.empty()) {
    253       LOG(ERROR) << "No valid Chrome version found";
    254       return NULL;
    255     }
    256 
    257     *out_file = dir;
    258     *out_version = version_string;
    259     out_file->append(*out_version).append(1, L'\\');
    260     dll = LoadChromeWithDirectory(out_file);
    261     if (!dll) {
    262       PLOG(ERROR) << "Failed to load Chrome DLL from " << *out_file;
    263       return NULL;
    264     }
    265   }
    266 
    267   DCHECK(dll);
    268 
    269   return dll;
    270 }
    271 
    272 // Launching is a matter of loading the right dll, setting the CHROME_VERSION
    273 // environment variable and just calling the entry point. Derived classes can
    274 // add custom code in the OnBeforeLaunch callback.
    275 int MainDllLoader::Launch(HINSTANCE instance,
    276                           sandbox::SandboxInterfaceInfo* sbox_info) {
    277   string16 version;
    278   string16 file;
    279   dll_ = Load(&version, &file);
    280   if (!dll_)
    281     return chrome::RESULT_CODE_MISSING_DATA;
    282 
    283   scoped_ptr<base::Environment> env(base::Environment::Create());
    284   env->SetVar(chrome::kChromeVersionEnvVar, WideToUTF8(version));
    285   // TODO(erikwright): Remove this when http://crbug.com/174953 is fixed and
    286   // widely deployed.
    287   env->UnSetVar(env_vars::kGoogleUpdateIsMachineEnvVar);
    288 
    289   const CommandLine& cmd_line = *CommandLine::ForCurrentProcess();
    290   std::string process_type =
    291       cmd_line.GetSwitchValueASCII(switches::kProcessType);
    292   breakpad::InitCrashReporter(process_type);
    293   OnBeforeLaunch(file);
    294 
    295   DLL_MAIN entry_point =
    296       reinterpret_cast<DLL_MAIN>(::GetProcAddress(dll_, "ChromeMain"));
    297   if (!entry_point)
    298     return chrome::RESULT_CODE_BAD_PROCESS_TYPE;
    299 
    300   int rc = entry_point(instance, sbox_info);
    301   return OnBeforeExit(rc, file);
    302 }
    303 
    304 void MainDllLoader::RelaunchChromeBrowserWithNewCommandLineIfNeeded() {
    305   RelaunchChromeBrowserWithNewCommandLineIfNeededFunc relaunch_function =
    306       reinterpret_cast<RelaunchChromeBrowserWithNewCommandLineIfNeededFunc>(
    307           ::GetProcAddress(dll_,
    308                            "RelaunchChromeBrowserWithNewCommandLineIfNeeded"));
    309   if (!relaunch_function) {
    310     LOG(ERROR) << "Could not find exported function "
    311                << "RelaunchChromeBrowserWithNewCommandLineIfNeeded";
    312   } else {
    313     relaunch_function();
    314   }
    315 }
    316 
    317 //=============================================================================
    318 
    319 class ChromeDllLoader : public MainDllLoader {
    320  public:
    321   virtual string16 GetRegistryPath() {
    322     string16 key(google_update::kRegPathClients);
    323     BrowserDistribution* dist = BrowserDistribution::GetDistribution();
    324     key.append(L"\\").append(dist->GetAppGuid());
    325     return key;
    326   }
    327 
    328   virtual void OnBeforeLaunch(const string16& dll_path) {
    329     RecordDidRun(dll_path);
    330   }
    331 
    332   virtual int OnBeforeExit(int return_code, const string16& dll_path) {
    333     // NORMAL_EXIT_CANCEL is used for experiments when the user cancels
    334     // so we need to reset the did_run signal so omaha does not count
    335     // this run as active usage.
    336     if (chrome::RESULT_CODE_NORMAL_EXIT_CANCEL == return_code) {
    337       ClearDidRun(dll_path);
    338     }
    339     return return_code;
    340   }
    341 };
    342 
    343 //=============================================================================
    344 
    345 class ChromiumDllLoader : public MainDllLoader {
    346  public:
    347   virtual string16 GetRegistryPath() {
    348     BrowserDistribution* dist = BrowserDistribution::GetDistribution();
    349     return dist->GetVersionKey();
    350   }
    351 };
    352 
    353 MainDllLoader* MakeMainDllLoader() {
    354 #if defined(GOOGLE_CHROME_BUILD)
    355   return new ChromeDllLoader();
    356 #else
    357   return new ChromiumDllLoader();
    358 #endif
    359 }
    360