chrome/installer/util/copy_reg_key_work_item.cc

   1 // Copyright (c) 2011 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 // Implementation of a work item that replaces the contents of one registry key
   6 // with that of another (i.e., the destination is erased prior to the copy).
   7
   8 #include "chrome/installer/util/copy_reg_key_work_item.h"
   9
  10 #include <shlwapi.h>
  11
  12 #include "base/logging.h"
  13 #include "base/win/registry.h"
  14
  15 using base::win::RegKey;
  16
  17 CopyRegKeyWorkItem::~CopyRegKeyWorkItem() {
  18 }
  19
  20 CopyRegKeyWorkItem::CopyRegKeyWorkItem(HKEY predefined_root,
  21                                        const std::wstring& source_key_path,
  22                                        const std::wstring& dest_key_path,
  23                                        CopyOverWriteOption overwrite_option)
  24     : predefined_root_(predefined_root),
  25       source_key_path_(source_key_path),
  26       dest_key_path_(dest_key_path),
  27       overwrite_option_(overwrite_option),
  28       cleared_destination_(false) {
  29   DCHECK(predefined_root);
  30   // It's a safe bet that we don't want to copy or overwrite one of the root
  31   // trees.
  32   DCHECK(!source_key_path.empty());
  33   DCHECK(!dest_key_path.empty());
  34   DCHECK(overwrite_option == ALWAYS || overwrite_option == IF_NOT_PRESENT);
  35 }
  36
  37 bool CopyRegKeyWorkItem::Do() {
  38   if (source_key_path_.empty() || dest_key_path_.empty())
  39     return false;
  40
  41   // Leave immediately if we're not supposed to overwrite an existing key and
  42   // one is there.
  43   if (overwrite_option_ == IF_NOT_PRESENT &&
  44       RegKey(predefined_root_, dest_key_path_.c_str(),
  45              KEY_QUERY_VALUE).Valid()) {
  46     return true;
  47   }
  48
  49   RegistryKeyBackup backup;
  50   RegKey dest_key;
  51
  52   // Only try to make a backup if we're not configured to ignore failures.
  53   if (!ignore_failure_) {
  54     if (!backup.Initialize(predefined_root_, dest_key_path_.c_str())) {
  55       LOG(ERROR) << "Failed to backup destination for registry key copy.";
  56       return false;
  57     }
  58   }
  59
  60   // Delete the destination before attempting to copy.
  61   LONG result = SHDeleteKey(predefined_root_, dest_key_path_.c_str());
  62   if (result != ERROR_SUCCESS && result != ERROR_FILE_NOT_FOUND) {
  63     LOG(ERROR) << "Failed to delete key at " << dest_key_path_ << ", result: "
  64                << result;
  65   } else {
  66     cleared_destination_ = true;
  67     // We've just modified the registry, so remember any backup we may have
  68     // made so that Rollback can take us back where we started.
  69     backup_.swap(backup);
  70     // Make the copy.
  71     result = dest_key.Create(predefined_root_, dest_key_path_.c_str(),
  72                              KEY_WRITE);
  73     if (result != ERROR_SUCCESS) {
  74       LOG(ERROR) << "Failed to open destination key at " << dest_key_path_
  75                  << ", result: " << result;
  76     } else {
  77       result = SHCopyKey(predefined_root_, source_key_path_.c_str(),
  78                          dest_key.Handle(), 0);
  79       switch (result) {
  80         case ERROR_FILE_NOT_FOUND:
  81           // The source didn't exist, so neither should the destination.
  82           dest_key.Close();
  83           SHDeleteKey(predefined_root_, dest_key_path_.c_str());
  84           // Handle like a success.
  85           result = ERROR_SUCCESS;
  86           // -- Fall through to success case. --
  87         case ERROR_SUCCESS:
  88           break;
  89         default:
  90           LOG(ERROR) << "Failed to copy key from " << source_key_path_ << " to "
  91                      << dest_key_path_ << ", result: " << result;
  92           break;
  93       }
  94     }
  95   }
  96
  97   return ignore_failure_ ? true : (result == ERROR_SUCCESS);
  98 }
  99
 100 void CopyRegKeyWorkItem::Rollback() {
 101   if (ignore_failure_)
 102     return;
 103
 104   if (cleared_destination_) {
 105     // Delete anything in the key before restoring the backup in case new data
 106     // was written after Do().
 107     LONG result = SHDeleteKey(predefined_root_, dest_key_path_.c_str());
 108     if (result != ERROR_SUCCESS && result != ERROR_FILE_NOT_FOUND) {
 109       LOG(ERROR) << "Failed to delete key at " << dest_key_path_
 110                  << " in rollback, result: " << result;
 111     }
 112
 113     // Restore the old contents.  The restoration takes on its default security
 114     // attributes; any custom attributes are lost.
 115     if (!backup_.WriteTo(predefined_root_, dest_key_path_.c_str()))
 116       LOG(ERROR) << "Failed to restore key in rollback.";
 117   }
 118 }