chrome/installer/util/delete_tree_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 #include "chrome/installer/util/delete_tree_work_item.h"
   6
   7 #include <algorithm>
   8 #include <limits>
   9
  10 #include "base/files/file_util.h"
  11 #include "base/logging.h"
  12
  13 namespace {
  14
  15 // Casts a value of an unsigned type to a signed type of the same size provided
  16 // that there is no overflow.
  17 template<typename L, typename R>
  18 bool SafeCast(L left, R* right) {
  19   DCHECK(right);
  20   COMPILE_ASSERT(sizeof(left) == sizeof(right),
  21                  must_add_support_for_crazy_data_types);
  22   if (left > static_cast<L>(std::numeric_limits<R>::max()))
  23     return false;
  24   *right = static_cast<L>(left);
  25   return true;
  26 }
  27
  28 }  // namespace
  29
  30 DeleteTreeWorkItem::DeleteTreeWorkItem(
  31     const base::FilePath& root_path,
  32     const base::FilePath& temp_path,
  33     const std::vector<base::FilePath>& key_paths)
  34     : root_path_(root_path),
  35       temp_path_(temp_path),
  36       copied_to_backup_(false) {
  37   if (!SafeCast(key_paths.size(), &num_key_files_)) {
  38     NOTREACHED() << "Impossibly large key_paths collection";
  39   } else if (num_key_files_ != 0) {
  40     key_paths_.reset(new base::FilePath[num_key_files_]);
  41     key_backup_paths_.reset(new base::ScopedTempDir[num_key_files_]);
  42     std::copy(key_paths.begin(), key_paths.end(), &key_paths_[0]);
  43   }
  44 }
  45
  46 DeleteTreeWorkItem::~DeleteTreeWorkItem() {
  47 }
  48
  49 // We first try to move key_path_ to backup_path. If it succeeds, we go ahead
  50 // and move the rest.
  51 bool DeleteTreeWorkItem::Do() {
  52   // Go through all the key files and see if we can open them exclusively
  53   // with only the FILE_SHARE_DELETE flag.  Once we know we have all of them,
  54   // we can delete them.
  55   std::vector<HANDLE> opened_key_files;
  56   opened_key_files.reserve(num_key_files_);
  57   bool abort = false;
  58   for (ptrdiff_t i = 0; !abort && i != num_key_files_; ++i) {
  59     base::FilePath& key_file = key_paths_[i];
  60     base::ScopedTempDir& backup = key_backup_paths_[i];
  61     if (!ignore_failure_) {
  62       if (!backup.CreateUniqueTempDirUnderPath(temp_path_)) {
  63         PLOG(ERROR) << "Could not create temp dir in " << temp_path_.value();
  64         abort = true;
  65       } else if (!base::CopyFile(key_file,
  66                      backup.path().Append(key_file.BaseName()))) {
  67         PLOG(ERROR) << "Could not back up " << key_file.value()
  68                     << " to directory " << backup.path().value();
  69         abort = true;
  70         backup.Delete();
  71       }
  72     }
  73     if (!abort) {
  74       HANDLE file = ::CreateFile(key_file.value().c_str(), FILE_ALL_ACCESS,
  75                                  FILE_SHARE_DELETE, NULL, OPEN_EXISTING, 0,
  76                                  NULL);
  77       if (file != INVALID_HANDLE_VALUE) {
  78         VLOG(1) << "Acquired exclusive lock for key file: " << key_file.value();
  79         opened_key_files.push_back(file);
  80       } else {
  81         if (::GetLastError() != ERROR_FILE_NOT_FOUND)
  82           abort = true;
  83         PLOG(INFO) << "Failed to open " << key_file.value();
  84       }
  85     }
  86   }
  87
  88   if (!abort) {
  89     // We now hold exclusive locks with "share delete" permissions for each
  90     // of the key files and also have created backups of those files.
  91     // We can safely delete the key files now.
  92     for (ptrdiff_t i = 0; !abort && i != num_key_files_; ++i) {
  93       base::FilePath& key_file = key_paths_[i];
  94       if (!base::DeleteFile(key_file, true)) {
  95         // This should not really be possible because of the above.
  96         PLOG(DFATAL) << "Unexpectedly could not delete " << key_file.value();
  97         abort = true;
  98       }
  99     }
 100   }
 101
 102   std::for_each(opened_key_files.begin(), opened_key_files.end(), CloseHandle);
 103   opened_key_files.clear();
 104
 105   if (abort) {
 106     LOG(ERROR) << "Could not exclusively hold all key files.";
 107     return ignore_failure_;
 108   }
 109
 110   // Now that we've taken care of the key files, take care of the rest.
 111   if (!root_path_.empty() && base::PathExists(root_path_)) {
 112     if (!ignore_failure_) {
 113       if (!backup_path_.CreateUniqueTempDirUnderPath(temp_path_)) {
 114         PLOG(ERROR) << "Failed to get backup path in folder "
 115                     << temp_path_.value();
 116         return false;
 117       } else {
 118         base::FilePath backup =
 119             backup_path_.path().Append(root_path_.BaseName());
 120         if (!base::CopyDirectory(root_path_, backup, true)) {
 121           LOG(ERROR) << "can not copy " << root_path_.value()
 122                      << " to backup path " << backup.value();
 123           return false;
 124         } else {
 125           copied_to_backup_ = true;
 126         }
 127       }
 128     }
 129     if (!base::DeleteFile(root_path_, true)) {
 130       LOG(ERROR) << "can not delete " << root_path_.value();
 131       return ignore_failure_;
 132     }
 133   }
 134
 135   return true;
 136 }
 137
 138 // If there are files in backup paths move them back.
 139 void DeleteTreeWorkItem::Rollback() {
 140   if (ignore_failure_)
 141     return;
 142
 143   if (copied_to_backup_) {
 144     DCHECK(!backup_path_.path().empty());
 145     base::FilePath backup = backup_path_.path().Append(root_path_.BaseName());
 146     if (base::PathExists(backup))
 147       base::Move(backup, root_path_);
 148   }
 149
 150   for (ptrdiff_t i = 0; i != num_key_files_; ++i) {
 151     base::ScopedTempDir& backup_dir = key_backup_paths_[i];
 152     if (!backup_dir.path().empty()) {
 153       base::FilePath& key_file = key_paths_[i];
 154       base::FilePath backup_file =
 155           backup_dir.path().Append(key_file.BaseName());
 156       if (base::PathExists(backup_file) &&
 157           !base::Move(backup_file, key_file)) {
 158         // This could happen if we could not delete the key file to begin with.
 159         PLOG(WARNING) << "Rollback: Failed to move backup file back in place: "
 160                       << backup_file.value() << " to " << key_file.value();
 161       }
 162     }
 163   }
 164 }