root/chrome/installer/mini_installer/mini_installer.cc

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DEFINITIONS

This source file includes following definitions.
  1. is_valid
  2. Open
  3. ReadValue
  4. WriteValue
  5. Close
  6. ReadValueFromRegistry
  7. OpenClientStateKey
  8. SetInstallerFlags
  9. GetSetupExePathForGuidFromRegistry
  10. GetSetupExePathFromRegistry
  11. RunProcessAndWait
  12. AppendCommandLineFlags
  13. OnResourceFound
  14. UnpackBinaryResources
  15. RunSetup
  16. DeleteExtractedFiles
  17. CreateWorkDir
  18. GetWorkDir
  19. IsCurrentOrParentDirectory
  20. RecursivelyDeleteDirectory
  21. DeleteDirectoriesWithPrefix
  22. DeleteOldChromeTempDirectories
  23. ProcessNonInstallOperations
  24. ShouldDeleteExtractedFiles
  25. WMain
  26. MainEntryPoint
  27. memset

// 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.

// mini_installer.exe is the first exe that is run when chrome is being
// installed or upgraded. It is designed to be extremely small (~5KB with no
// extra resources linked) and it has two main jobs:
//   1) unpack the resources (possibly decompressing some)
//   2) run the real installer (setup.exe) with appropriate flags.
//
// In order to be really small the app doesn't link against the CRT and
// defines the following compiler/linker flags:
//   EnableIntrinsicFunctions="true" compiler: /Oi
//   BasicRuntimeChecks="0"
//   BufferSecurityCheck="false" compiler: /GS-
//   EntryPointSymbol="MainEntryPoint" linker: /ENTRY
//   IgnoreAllDefaultLibraries="true" linker: /NODEFAULTLIB
//   OptimizeForWindows98="1"  liker: /OPT:NOWIN98
//   linker: /SAFESEH:NO

// have the linker merge the sections, saving us ~500 bytes.
#pragma comment(linker, "/MERGE:.rdata=.text")

#include <windows.h>
#include <shellapi.h>

#include "chrome/installer/mini_installer/appid.h"
#include "chrome/installer/mini_installer/configuration.h"
#include "chrome/installer/mini_installer/decompress.h"
#include "chrome/installer/mini_installer/mini_installer.h"
#include "chrome/installer/mini_installer/mini_string.h"
#include "chrome/installer/mini_installer/pe_resource.h"

namespace mini_installer {

typedef StackString<MAX_PATH> PathString;
typedef StackString<MAX_PATH * 4> CommandString;

// This structure passes data back and forth for the processing
// of resource callbacks.
struct Context {
  // Input to the call back method. Specifies the dir to save resources.
  const wchar_t* base_path;
  // First output from call back method. Full path of Chrome archive.
  PathString* chrome_resource_path;
  // Second output from call back method. Full path of Setup archive/exe.
  PathString* setup_resource_path;
};

// A helper class used to manipulate the Windows registry.  Typically, members
// return Windows last-error codes a la the Win32 registry API.
class RegKey {
 public:
  RegKey() : key_(NULL) { }
  ~RegKey() { Close(); }

  // Opens the key named |sub_key| with given |access| rights.  Returns
  // ERROR_SUCCESS or some other error.
  LONG Open(HKEY key, const wchar_t* sub_key, REGSAM access);

  // Returns true if a key is open.
  bool is_valid() const { return key_ != NULL; }

  // Read a REG_SZ value from the registry into the memory indicated by |value|
  // (of |value_size| wchar_t units).  Returns ERROR_SUCCESS,
  // ERROR_FILE_NOT_FOUND, ERROR_MORE_DATA, or some other error.  |value| is
  // guaranteed to be null-terminated on success.
  LONG ReadValue(const wchar_t* value_name,
                 wchar_t* value,
                 size_t value_size) const;

  // Write a REG_SZ value to the registry.  |value| must be null-terminated.
  // Returns ERROR_SUCCESS or an error code.
  LONG WriteValue(const wchar_t* value_name, const wchar_t* value);

  // Closes the key if it was open.
  void Close();

 private:
  RegKey(const RegKey&);
  RegKey& operator=(const RegKey&);

  HKEY key_;
};  // class RegKey

LONG RegKey::Open(HKEY key, const wchar_t* sub_key, REGSAM access) {
  Close();
  return ::RegOpenKeyEx(key, sub_key, NULL, access, &key_);
}

LONG RegKey::ReadValue(const wchar_t* value_name,
                       wchar_t* value,
                       size_t value_size) const {
  DWORD type;
  DWORD byte_length = static_cast<DWORD>(value_size * sizeof(wchar_t));
  LONG result = ::RegQueryValueEx(key_, value_name, NULL, &type,
                                  reinterpret_cast<BYTE*>(value),
                                  &byte_length);
  if (result == ERROR_SUCCESS) {
    if (type != REG_SZ) {
      result = ERROR_NOT_SUPPORTED;
    } else if (byte_length == 0) {
      *value = L'\0';
    } else if (value[byte_length/sizeof(wchar_t) - 1] != L'\0') {
      if ((byte_length / sizeof(wchar_t)) < value_size)
        value[byte_length / sizeof(wchar_t)] = L'\0';
      else
        result = ERROR_MORE_DATA;
    }
  }
  return result;
}

LONG RegKey::WriteValue(const wchar_t* value_name, const wchar_t* value) {
  return ::RegSetValueEx(key_, value_name, 0, REG_SZ,
                         reinterpret_cast<const BYTE*>(value),
                         (lstrlen(value) + 1) * sizeof(wchar_t));
}

void RegKey::Close() {
  if (key_ != NULL) {
    ::RegCloseKey(key_);
    key_ = NULL;
  }
}

// Helper function to read a value from registry. Returns true if value
// is read successfully and stored in parameter value. Returns false otherwise.
// |size| is measured in wchar_t units.
bool ReadValueFromRegistry(HKEY root_key, const wchar_t *sub_key,
                           const wchar_t *value_name, wchar_t *value,
                           size_t size) {
  RegKey key;

  if (key.Open(root_key, sub_key, KEY_QUERY_VALUE) == ERROR_SUCCESS &&
      key.ReadValue(value_name, value, size) == ERROR_SUCCESS) {
    return true;
  }
  return false;
}

// Opens the Google Update ClientState key for a product.
bool OpenClientStateKey(HKEY root_key, const wchar_t* app_guid, REGSAM access,
                        RegKey* key) {
  PathString client_state_key;
  return client_state_key.assign(kApRegistryKeyBase) &&
         client_state_key.append(app_guid) &&
         (key->Open(root_key, client_state_key.get(), access) == ERROR_SUCCESS);
}

// This function sets the flag in registry to indicate that Google Update
// should try full installer next time. If the current installer works, this
// flag is cleared by setup.exe at the end of install. The flag will by default
// be written to HKCU, but if --system-level is included in the command line,
// it will be written to HKLM instead.
// TODO(grt): Write a unit test for this that uses registry virtualization.
void SetInstallerFlags(const Configuration& configuration) {
  RegKey key;
  const REGSAM key_access = KEY_QUERY_VALUE | KEY_SET_VALUE;
  const HKEY root_key =
      configuration.is_system_level() ? HKEY_LOCAL_MACHINE : HKEY_CURRENT_USER;
  // This is ignored if multi-install is true.
  const wchar_t* app_guid =
      configuration.has_chrome_frame() ?
          google_update::kChromeFrameAppGuid :
          configuration.chrome_app_guid();
  StackString<128> value;
  LONG ret;

  // When multi_install is true, we are potentially:
  // 1. Performing a multi-install of some product(s) on a clean machine.
  //    Neither the product(s) nor the multi-installer will have a ClientState
  //    key in the registry, so there is nothing to be done.
  // 2. Upgrading an existing multi-install.  The multi-installer will have a
  //    ClientState key in the registry.  Only it need be modified.
  // 3. Migrating a single-install into a multi-install.  The product will have
  //    a ClientState key in the registry.  Only it need be modified.
  // To handle all cases, we inspect the product's ClientState to see if it
  // exists and its "ap" value does not contain "-multi".  This is case 3, so we
  // modify the product's ClientState.  Otherwise, we check the
  // multi-installer's ClientState and modify it if it exists.
  if (configuration.is_multi_install()) {
    if (OpenClientStateKey(root_key, app_guid, key_access, &key)) {
      // The product has a client state key.  See if it's a single-install.
      ret = key.ReadValue(kApRegistryValueName, value.get(), value.capacity());
      if (ret != ERROR_FILE_NOT_FOUND &&
          (ret != ERROR_SUCCESS ||
           FindTagInStr(value.get(), kMultiInstallTag, NULL))) {
        // Error or case 2: modify the multi-installer's value.
        key.Close();
        app_guid = google_update::kMultiInstallAppGuid;
      }  // else case 3: modify this value.
    } else {
      // case 1 or 2: modify the multi-installer's value.
      key.Close();
      app_guid = google_update::kMultiInstallAppGuid;
    }
  }

  if (!key.is_valid()) {
    if (!OpenClientStateKey(root_key, app_guid, key_access, &key))
      return;

    value.clear();
    ret = key.ReadValue(kApRegistryValueName, value.get(), value.capacity());
  }

  // The conditions below are handling two cases:
  // 1. When ap value is present, we want to add the required tag only if it is
  //    not present.
  // 2. When ap value is missing, we are going to create it with the required
  //    tag.
  if ((ret == ERROR_SUCCESS) || (ret == ERROR_FILE_NOT_FOUND)) {
    if (ret == ERROR_FILE_NOT_FOUND)
      value.clear();

    if (!StrEndsWith(value.get(), kFullInstallerSuffix) &&
        value.append(kFullInstallerSuffix)) {
      key.WriteValue(kApRegistryValueName, value.get());
    }
  }
}

// Gets the setup.exe path from Registry by looking the value of Uninstall
// string.  |size| is measured in wchar_t units.
bool GetSetupExePathForGuidFromRegistry(bool system_level,
                                        const wchar_t* app_guid,
                                        wchar_t* path,
                                        size_t size) {
  const HKEY root_key = system_level ? HKEY_LOCAL_MACHINE : HKEY_CURRENT_USER;
  RegKey key;
  return OpenClientStateKey(root_key, app_guid, KEY_QUERY_VALUE, &key) &&
      (key.ReadValue(kUninstallRegistryValueName, path, size) == ERROR_SUCCESS);
}

// Gets the setup.exe path from Registry by looking the value of Uninstall
// string.  |size| is measured in wchar_t units.
bool GetSetupExePathFromRegistry(const Configuration& configuration,
                                 wchar_t* path,
                                 size_t size) {
  bool system_level = configuration.is_system_level();

  // If this is a multi install, first try looking in the binaries for the path.
  if (configuration.is_multi_install() && GetSetupExePathForGuidFromRegistry(
          system_level, google_update::kMultiInstallAppGuid, path, size)) {
    return true;
  }

  // Failing that, look in Chrome Frame's client state key if --chrome-frame was
  // specified.
  if (configuration.has_chrome_frame() && GetSetupExePathForGuidFromRegistry(
          system_level, google_update::kChromeFrameAppGuid, path, size)) {
    return true;
  }

  // Make a last-ditch effort to look in the Chrome and App Host client state
  // keys.
  if (GetSetupExePathForGuidFromRegistry(
          system_level, configuration.chrome_app_guid(), path, size)) {
    return true;
  }
  if (configuration.has_app_host() && GetSetupExePathForGuidFromRegistry(
          system_level, google_update::kChromeAppHostAppGuid, path, size)) {
    return true;
  }

  return false;
}

// Calls CreateProcess with good default parameters and waits for the process
// to terminate returning the process exit code.
bool RunProcessAndWait(const wchar_t* exe_path, wchar_t* cmdline,
                       int* exit_code) {
  STARTUPINFOW si = {sizeof(si)};
  PROCESS_INFORMATION pi = {0};
  if (!::CreateProcess(exe_path, cmdline, NULL, NULL, FALSE, CREATE_NO_WINDOW,
                       NULL, NULL, &si, &pi)) {
    return false;
  }

  ::CloseHandle(pi.hThread);

  bool ret = true;
  DWORD wr = ::WaitForSingleObject(pi.hProcess, INFINITE);
  if (WAIT_OBJECT_0 != wr) {
    ret = false;
  } else if (exit_code) {
    if (!::GetExitCodeProcess(pi.hProcess,
                              reinterpret_cast<DWORD*>(exit_code))) {
      ret = false;
    }
  }

  ::CloseHandle(pi.hProcess);

  return ret;
}

// Append any command line params passed to mini_installer to the given buffer
// so that they can be passed on to setup.exe. We do not return any error from
// this method and simply skip making any changes in case of error.
void AppendCommandLineFlags(const Configuration& configuration,
                            CommandString* buffer) {
  PathString full_exe_path;
  size_t len = ::GetModuleFileName(NULL, full_exe_path.get(),
                                   full_exe_path.capacity());
  if (!len || len >= full_exe_path.capacity())
    return;

  const wchar_t* exe_name = GetNameFromPathExt(full_exe_path.get(), len);
  if (exe_name == NULL)
    return;

  const wchar_t* cmd_to_append = L"";
  if (!StrEndsWith(configuration.program(), exe_name)) {
    // Current executable name not in the command line so just append
    // the whole command line.
    cmd_to_append = configuration.command_line();
  } else if (configuration.argument_count() > 1) {
    const wchar_t* tmp = SearchStringI(configuration.command_line(), exe_name);
    tmp = SearchStringI(tmp, L" ");
    cmd_to_append = tmp;
  }

  buffer->append(cmd_to_append);
}


// Windows defined callback used in the EnumResourceNames call. For each
// matching resource found, the callback is invoked and at this point we write
// it to disk. We expect resource names to start with 'chrome' or 'setup'. Any
// other name is treated as an error.
BOOL CALLBACK OnResourceFound(HMODULE module, const wchar_t* type,
                              wchar_t* name, LONG_PTR context) {
  if (NULL == context)
    return FALSE;

  Context* ctx = reinterpret_cast<Context*>(context);

  PEResource resource(name, type, module);
  if ((!resource.IsValid()) ||
      (resource.Size() < 1) ||
      (resource.Size() > kMaxResourceSize)) {
    return FALSE;
  }

  PathString full_path;
  if (!full_path.assign(ctx->base_path) ||
      !full_path.append(name) ||
      !resource.WriteToDisk(full_path.get()))
    return FALSE;

  if (StrStartsWith(name, kChromePrefix)) {
    if (!ctx->chrome_resource_path->assign(full_path.get()))
      return FALSE;
  } else if (StrStartsWith(name, kSetupPrefix)) {
    if (!ctx->setup_resource_path->assign(full_path.get()))
      return FALSE;
  } else {
    // Resources should either start with 'chrome' or 'setup'. We don't handle
    // anything else.
    return FALSE;
  }

  return TRUE;
}

// Finds and writes to disk resources of various types. Returns false
// if there is a problem in writing any resource to disk. setup.exe resource
// can come in one of three possible forms:
// - Resource type 'B7', compressed using LZMA (*.7z)
// - Resource type 'BL', compressed using LZ (*.ex_)
// - Resource type 'BN', uncompressed (*.exe)
// If setup.exe is present in more than one form, the precedence order is
// BN < BL < B7
// For more details see chrome/tools/build/win/create_installer_archive.py.
bool UnpackBinaryResources(const Configuration& configuration, HMODULE module,
                           const wchar_t* base_path, PathString* archive_path,
                           PathString* setup_path) {
  // Generate the setup.exe path where we patch/uncompress setup resource.
  PathString setup_dest_path;
  if (!setup_dest_path.assign(base_path) ||
      !setup_dest_path.append(kSetupName))
    return false;

  // Prepare the input to OnResourceFound method that needs a location where
  // it will write all the resources.
  Context context = {
    base_path,
    archive_path,
    setup_path,
  };

  // Get the resources of type 'B7' (7zip archive).
  // We need a chrome archive to do the installation. So if there
  // is a problem in fetching B7 resource, just return an error.
  if (!::EnumResourceNames(module, kLZMAResourceType, OnResourceFound,
                           reinterpret_cast<LONG_PTR>(&context)) ||
      archive_path->length() == 0)
    return false;

  // If we found setup 'B7' resource, handle it.
  if (setup_path->length() > 0) {
    CommandString cmd_line;
    // Get the path to setup.exe first.
    bool success = true;
    if (!GetSetupExePathFromRegistry(configuration, cmd_line.get(),
                                     cmd_line.capacity()) ||
        !cmd_line.append(kCmdUpdateSetupExe) ||
        !cmd_line.append(L"=\"") ||
        !cmd_line.append(setup_path->get()) ||
        !cmd_line.append(L"\"") ||
        !cmd_line.append(kCmdNewSetupExe) ||
        !cmd_line.append(L"=\"") ||
        !cmd_line.append(setup_dest_path.get()) ||
        !cmd_line.append(L"\"")) {
      success = false;
    }

    // Get any command line option specified for mini_installer and pass them
    // on to setup.exe.  This is important since switches such as
    // --multi-install and --chrome-frame affect where setup.exe will write
    // installer results for consumption by Google Update.
    AppendCommandLineFlags(configuration, &cmd_line);

    int exit_code = 0;
    if (success &&
        (!RunProcessAndWait(NULL, cmd_line.get(), &exit_code) ||
         exit_code != ERROR_SUCCESS)) {
      success = false;
    }

    if (!success)
      DeleteFile(setup_path->get());

    return success && setup_path->assign(setup_dest_path.get());
  }

  // setup.exe wasn't sent as 'B7', lets see if it was sent as 'BL'
  // (compressed setup).
  if (!::EnumResourceNames(module, kLZCResourceType, OnResourceFound,
                           reinterpret_cast<LONG_PTR>(&context)) &&
      ::GetLastError() != ERROR_RESOURCE_TYPE_NOT_FOUND)
    return false;

  if (setup_path->length() > 0) {
    // Uncompress LZ compressed resource. Setup is packed with 'MSCF'
    // as opposed to old DOS way of 'SZDD'. Hence we don't use LZCopy.
    bool success = mini_installer::Expand(setup_path->get(),
                                          setup_dest_path.get());
    ::DeleteFile(setup_path->get());
    if (success) {
      if (!setup_path->assign(setup_dest_path.get())) {
        ::DeleteFile(setup_dest_path.get());
        success = false;
      }
    }

    return success;
  }

  // setup.exe still not found. So finally check if it was sent as 'BN'
  // (uncompressed setup).
  // TODO(tommi): We don't need BN anymore so let's remove it (and remove
  // it from create_installer_archive.py).
  if (!::EnumResourceNames(module, kBinResourceType, OnResourceFound,
                           reinterpret_cast<LONG_PTR>(&context)) &&
      ::GetLastError() != ERROR_RESOURCE_TYPE_NOT_FOUND)
    return false;

  if (setup_path->length() > 0) {
    if (setup_path->comparei(setup_dest_path.get()) != 0) {
      if (!::MoveFileEx(setup_path->get(), setup_dest_path.get(),
                        MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING)) {
        ::DeleteFile(setup_path->get());
        setup_path->clear();
      } else if (!setup_path->assign(setup_dest_path.get())) {
        ::DeleteFile(setup_dest_path.get());
      }
    }
  }

  return setup_path->length() > 0;
}

// Executes setup.exe, waits for it to finish and returns the exit code.
bool RunSetup(const Configuration& configuration, const wchar_t* archive_path,
              const wchar_t* setup_path, int* exit_code) {
  // There could be three full paths in the command line for setup.exe (path
  // to exe itself, path to archive and path to log file), so we declare
  // total size as three + one additional to hold command line options.
  CommandString cmd_line;

  // Get the path to setup.exe first.
  if (::lstrlen(setup_path) > 0) {
    if (!cmd_line.assign(L"\"") ||
        !cmd_line.append(setup_path) ||
        !cmd_line.append(L"\""))
      return false;
  } else if (!GetSetupExePathFromRegistry(configuration, cmd_line.get(),
                                          cmd_line.capacity())) {
    return false;
  }

  // Append the command line param for chrome archive file
  if (!cmd_line.append(kCmdInstallArchive) ||
      !cmd_line.append(L"=\"") ||
      !cmd_line.append(archive_path) ||
      !cmd_line.append(L"\""))
    return false;

  // Get any command line option specified for mini_installer and pass them
  // on to setup.exe
  AppendCommandLineFlags(configuration, &cmd_line);

  return RunProcessAndWait(NULL, cmd_line.get(), exit_code);
}

// Deletes given files and working dir.
void DeleteExtractedFiles(const wchar_t* base_path,
                          const wchar_t* archive_path,
                          const wchar_t* setup_path) {
  ::DeleteFile(archive_path);
  ::DeleteFile(setup_path);
  // Delete the temp dir (if it is empty, otherwise fail).
  ::RemoveDirectory(base_path);
}

// Creates a temporary directory under |base_path| and returns the full path
// of created directory in |work_dir|. If successful return true, otherwise
// false.  When successful, the returned |work_dir| will always have a trailing
// backslash and this function requires that |base_path| always includes a
// trailing backslash as well.
// We do not use GetTempFileName here to avoid running into AV software that
// might hold on to the temp file as soon as we create it and then we can't
// delete it and create a directory in its place.  So, we use our own mechanism
// for creating a directory with a hopefully-unique name.  In the case of a
// collision, we retry a few times with a new name before failing.
bool CreateWorkDir(const wchar_t* base_path, PathString* work_dir) {
  if (!work_dir->assign(base_path) || !work_dir->append(kTempPrefix))
    return false;

  // Store the location where we'll append the id.
  size_t end = work_dir->length();

  // Check if we'll have enough buffer space to continue.
  // The name of the directory will use up 11 chars and then we need to append
  // the trailing backslash and a terminator.  We've already added the prefix
  // to the buffer, so let's just make sure we've got enough space for the rest.
  if ((work_dir->capacity() - end) < (arraysize("fffff.tmp") + 1))
    return false;

  // Generate a unique id.  We only use the lowest 20 bits, so take the top
  // 12 bits and xor them with the lower bits.
  DWORD id = ::GetTickCount();
  id ^= (id >> 12);

  int max_attempts = 10;
  while (max_attempts--) {
    // This converts 'id' to a string in the format "78563412" on windows
    // because of little endianness, but we don't care since it's just
    // a name.
    if (!HexEncode(&id, sizeof(id), work_dir->get() + end,
                   work_dir->capacity() - end)) {
      return false;
    }

    // We only want the first 5 digits to remain within the 8.3 file name
    // format (compliant with previous implementation).
    work_dir->truncate_at(end + 5);

    // for consistency with the previous implementation which relied on
    // GetTempFileName, we append the .tmp extension.
    work_dir->append(L".tmp");
    if (::CreateDirectory(work_dir->get(), NULL)) {
      // Yay!  Now let's just append the backslash and we're done.
      return work_dir->append(L"\\");
    }
    ++id;  // Try a different name.
  }

  return false;
}

// Creates and returns a temporary directory that can be used to extract
// mini_installer payload.
bool GetWorkDir(HMODULE module, PathString* work_dir) {
  PathString base_path;
  DWORD len = ::GetTempPath(base_path.capacity(), base_path.get());
  if (!len || len >= base_path.capacity() ||
      !CreateWorkDir(base_path.get(), work_dir)) {
    // Problem creating the work dir under TEMP path, so try using the
    // current directory as the base path.
    len = ::GetModuleFileName(module, base_path.get(), base_path.capacity());
    if (len >= base_path.capacity() || !len)
      return false;  // Can't even get current directory? Return an error.

    wchar_t* name = GetNameFromPathExt(base_path.get(), len);
    if (!name)
      return false;

    *name = L'\0';

    return CreateWorkDir(base_path.get(), work_dir);
  }
  return true;
}

// Returns true for ".." and "." directories.
bool IsCurrentOrParentDirectory(const wchar_t* dir) {
  return dir &&
         dir[0] == L'.' &&
         (dir[1] == L'\0' || (dir[1] == L'.' && dir[2] == L'\0'));
}

// Best effort directory tree deletion including the directory specified
// by |path|, which must not end in a separator.
// The |path| argument is writable so that each recursion can use the same
// buffer as was originally allocated for the path.  The path will be unchanged
// upon return.
void RecursivelyDeleteDirectory(PathString* path) {
  // |path| will never have a trailing backslash.
  size_t end = path->length();
  if (!path->append(L"\\*.*"))
    return;

  WIN32_FIND_DATA find_data = {0};
  HANDLE find = ::FindFirstFile(path->get(), &find_data);
  if (find != INVALID_HANDLE_VALUE) {
    do {
      // Use the short name if available to make the most of our buffer.
      const wchar_t* name = find_data.cAlternateFileName[0] ?
          find_data.cAlternateFileName : find_data.cFileName;
      if (IsCurrentOrParentDirectory(name))
        continue;

      path->truncate_at(end + 1);  // Keep the trailing backslash.
      if (!path->append(name))
        continue;  // Continue in spite of too long names.

      if (find_data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
        RecursivelyDeleteDirectory(path);
      } else {
        ::DeleteFile(path->get());
      }
    } while (::FindNextFile(find, &find_data));
    ::FindClose(find);
  }

  // Restore the path and delete the directory before we return.
  path->truncate_at(end);
  ::RemoveDirectory(path->get());
}

// Enumerates subdirectories of |parent_dir| and deletes all subdirectories
// that match with a given |prefix|.  |parent_dir| must have a trailing
// backslash.
// The process is done on a best effort basis, so conceivably there might
// still be matches left when the function returns.
void DeleteDirectoriesWithPrefix(const wchar_t* parent_dir,
                                 const wchar_t* prefix) {
  // |parent_dir| is guaranteed to always have a trailing backslash.
  PathString spec;
  if (!spec.assign(parent_dir) || !spec.append(prefix) || !spec.append(L"*.*"))
    return;

  WIN32_FIND_DATA find_data = {0};
  HANDLE find = ::FindFirstFileEx(spec.get(), FindExInfoStandard, &find_data,
                                  FindExSearchLimitToDirectories, NULL, 0);
  if (find == INVALID_HANDLE_VALUE)
    return;

  PathString path;
  do {
    if (find_data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
      // Use the short name if available to make the most of our buffer.
      const wchar_t* name = find_data.cAlternateFileName[0] ?
          find_data.cAlternateFileName : find_data.cFileName;
      if (IsCurrentOrParentDirectory(name))
        continue;
      if (path.assign(parent_dir) && path.append(name))
        RecursivelyDeleteDirectory(&path);
    }
  } while (::FindNextFile(find, &find_data));
  ::FindClose(find);
}

// Attempts to free up space by deleting temp directories that previous
// installer runs have failed to clean up.
void DeleteOldChromeTempDirectories() {
  static const wchar_t* const kDirectoryPrefixes[] = {
    kTempPrefix,
    L"chrome_"  // Previous installers created directories with this prefix
                // and there are still some lying around.
  };

  PathString temp;
  // GetTempPath always returns a path with a trailing backslash.
  DWORD len = ::GetTempPath(temp.capacity(), temp.get());
  // GetTempPath returns 0 or number of chars copied, not including the
  // terminating '\0'.
  if (!len || len >= temp.capacity())
    return;

  for (int i = 0; i < arraysize(kDirectoryPrefixes); ++i) {
    DeleteDirectoriesWithPrefix(temp.get(), kDirectoryPrefixes[i]);
  }
}

// Checks the command line for specific mini installer flags.
// If the function returns true, the command line has been processed and all
// required actions taken.  The installer must exit and return the returned
// |exit_code|.
bool ProcessNonInstallOperations(const Configuration& configuration,
                                 int* exit_code) {
  bool ret = false;

  switch (configuration.operation()) {
    case Configuration::CLEANUP:
      // Cleanup has already taken place in DeleteOldChromeTempDirectories at
      // this point, so just tell our caller to exit early.
      *exit_code = 0;
      ret = true;
      break;

    default: break;
  }

  return ret;
}

// Returns true if we should delete the temp files we create (default).
// Returns false iff the user has manually created a ChromeInstallerCleanup
// string value in the registry under HKCU\\Software\\[Google|Chromium]
// and set its value to "0".  That explicitly forbids the mini installer from
// deleting these files.
// Support for this has been publicly mentioned in troubleshooting tips so
// we continue to support it.
bool ShouldDeleteExtractedFiles() {
  wchar_t value[2] = {0};
  if (ReadValueFromRegistry(HKEY_CURRENT_USER, kCleanupRegistryKey,
                            kCleanupRegistryValueName, value,
                            arraysize(value)) &&
      value[0] == L'0') {
    return false;
  }

  return true;
}

// Main function. First gets a working dir, unpacks the resources and finally
// executes setup.exe to do the install/upgrade.
int WMain(HMODULE module) {
#if defined(COMPONENT_BUILD)
  static const wchar_t kComponentBuildIncompatibleMessage[] =
      L"mini_installer.exe is incompatible with the component build, please run"
      L" setup.exe with the same command line instead. See"
      L" http://crbug.com/127233#c17 for details.";
  ::MessageBox(NULL, kComponentBuildIncompatibleMessage, NULL, MB_ICONERROR);
  return 1;
#endif

  // Always start with deleting potential leftovers from previous installations.
  // This can make the difference between success and failure.  We've seen
  // many installations out in the field fail due to out of disk space problems
  // so this could buy us some space.
  DeleteOldChromeTempDirectories();

  // TODO(grt): Make the exit codes more granular so we know where the popular
  // errors truly are.
  int exit_code = 101;

  // Parse the command line.
  Configuration configuration;
  if (!configuration.Initialize())
    return exit_code;

  // If the --cleanup switch was specified on the command line, then that means
  // we should only do the cleanup and then exit.
  if (ProcessNonInstallOperations(configuration, &exit_code))
    return exit_code;

  // First get a path where we can extract payload
  PathString base_path;
  if (!GetWorkDir(module, &base_path))
    return 101;

#if defined(GOOGLE_CHROME_BUILD)
  // Set the magic suffix in registry to try full installer next time. We ignore
  // any errors here and we try to set the suffix for user level unless
  // --system-level is on the command line in which case we set it for system
  // level instead. This only applies to the Google Chrome distribution.
  SetInstallerFlags(configuration);
#endif

  PathString archive_path;
  PathString setup_path;
  if (!UnpackBinaryResources(configuration, module, base_path.get(),
                             &archive_path, &setup_path)) {
    exit_code = 102;
  } else {
    // While unpacking the binaries, we paged in a whole bunch of memory that
    // we don't need anymore.  Let's give it back to the pool before running
    // setup.
    ::SetProcessWorkingSetSize(::GetCurrentProcess(), -1, -1);
    if (!RunSetup(configuration, archive_path.get(), setup_path.get(),
                  &exit_code)) {
      exit_code = 103;
    }
  }

  if (ShouldDeleteExtractedFiles())
    DeleteExtractedFiles(base_path.get(), archive_path.get(), setup_path.get());

  return exit_code;
}

}  // namespace mini_installer

int MainEntryPoint() {
  int result = mini_installer::WMain(::GetModuleHandle(NULL));
  ::ExitProcess(result);
}

// VC Express editions don't come with the memset CRT obj file and linking to
// the obj files between versions becomes a bit problematic. Therefore,
// simply implement memset.
//
// This also avoids having to explicitly set the __sse2_available hack when
// linking with both the x64 and x86 obj files which is required when not
// linking with the std C lib in certain instances (including Chromium) with
// MSVC.  __sse2_available determines whether to use SSE2 intructions with
// std C lib routines, and is set by MSVC's std C lib implementation normally.
extern "C" {
#pragma function(memset)
void* memset(void* dest, int c, size_t count) {
  // Simplistic 32-bit memset C implementation which assumes properly aligned
  // memory; performance hit on memory that isn't properly aligned, but still
  // better overall then a 8-bit implementation.
  size_t adjcount = count >> 2;
  UINT32 fill = (c << 24 | c << 16 | c << 8 | c);
  UINT32* dest32 = reinterpret_cast<UINT32*>(dest);
  UINT8* dest8 = reinterpret_cast<UINT8*>(dest);

  // Take care of the ending 0-3 bytes (binary 11 = 3).  The lack of breaks is
  // deliberate; it falls through for each byte. Think of it a simplified for
  // loop.
  switch (count - (adjcount << 2)) {
    case 3:
      dest8[count - 3] = c;
    case 2:
      dest8[count - 2] = c;
    case 1:
      dest8[count - 1] = c;
  }

  while (adjcount-- > 0)  // Copy the rest, 4 bytes/32 bits at a time
    *(dest32++) = fill;

  return dest;
}
}  // extern "C"

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