delete_reg_value_work_item.cc revision 5821806d5e7f356e8fa4b058a389a808ea183019 
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 "chrome/installer/util/delete_reg_value_work_item.h"
6
7#include "base/logging.h"
8#include "base/string_util.h"
9#include "base/win/registry.h"
10#include "chrome/installer/util/logging_installer.h"
11
12using base::win::RegKey;
13
14DeleteRegValueWorkItem::DeleteRegValueWorkItem(HKEY predefined_root,
15                                               const std::wstring& key_path,
16                                               const std::wstring& value_name)
17    : predefined_root_(predefined_root),
18      key_path_(key_path),
19      value_name_(value_name),
20      previous_type_(0),
21      status_(DELETE_VALUE) {
22}
23
24DeleteRegValueWorkItem::~DeleteRegValueWorkItem() {
25}
26
27bool DeleteRegValueWorkItem::Do() {
28  if (status_ != DELETE_VALUE) {
29    // we already did something.
30    LOG(ERROR) << "multiple calls to Do()";
31    return false;
32  }
33
34  status_ = VALUE_UNCHANGED;
35
36  RegKey key;
37  DWORD type = 0;
38  DWORD size = 0;
39  LONG result = key.Open(predefined_root_, key_path_.c_str(),
40                         KEY_READ | KEY_WRITE);
41  if (result == ERROR_SUCCESS)
42    result = key.ReadValue(value_name_.c_str(), NULL, &size, &type);
43
44  if (result == ERROR_FILE_NOT_FOUND) {
45    LOG(INFO) << "(delete value) Key: " << key_path_ << " or Value: "
46              << value_name_ << " does not exist.";
47    status_ = VALUE_NOT_FOUND;
48    return true;
49  }
50
51  if (result == ERROR_SUCCESS) {
52    if (!size) {
53      previous_type_ = type;
54    } else {
55      previous_value_.resize(size);
56      result = key.ReadValue(value_name_.c_str(), &previous_value_[0], &size,
57                             &previous_type_);
58      if (result != ERROR_SUCCESS) {
59        previous_value_.erase();
60        VLOG(1) << "Failed to save original value. Error: " << result;
61      }
62    }
63  }
64
65  result = key.DeleteValue(value_name_.c_str());
66  if (result != ERROR_SUCCESS) {
67    VLOG(1) << "Failed to delete value " << value_name_ << " error: " << result;
68    return false;
69  }
70
71  status_ = VALUE_DELETED;
72  return true;
73}
74
75void DeleteRegValueWorkItem::Rollback() {
76  if (status_ == DELETE_VALUE || status_ == VALUE_ROLLED_BACK)
77    return;
78  if (status_ == VALUE_UNCHANGED || status_ == VALUE_NOT_FOUND) {
79    status_ = VALUE_ROLLED_BACK;
80    VLOG(1) << "rollback: setting unchanged, nothing to do";
81    return;
82  }
83
84  // At this point only possible state is VALUE_DELETED.
85  RegKey key;
86  LONG result = key.Open(predefined_root_, key_path_.c_str(),
87                         KEY_READ | KEY_WRITE);
88  if (result == ERROR_SUCCESS) {
89    // try to restore the previous value
90    DWORD previous_size = static_cast<DWORD>(previous_value_.size());
91    const char* previous_value =
92        previous_size ? &previous_value_[0] : NULL;
93    result = key.WriteValue(value_name_.c_str(), previous_value,
94                            previous_size, previous_type_);
95    VLOG_IF(1, result != ERROR_SUCCESS) << "rollback: restoring "
96                                        << value_name_ << " error: " << result;
97  } else {
98    VLOG(1) << "can not open " << key_path_ << " error: " << result;
99  }
100}
101