configuration_policy_provider_win.h revision 513209b27ff55e2841eac0e4120199c23acce758 
1// Copyright (c) 2010 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#ifndef CHROME_BROWSER_POLICY_CONFIGURATION_POLICY_PROVIDER_WIN_H_
6#define CHROME_BROWSER_POLICY_CONFIGURATION_POLICY_PROVIDER_WIN_H_
7#pragma once
8
9#include "base/object_watcher.h"
10#include "base/ref_counted.h"
11#include "base/scoped_ptr.h"
12#include "base/waitable_event.h"
13#include "base/weak_ptr.h"
14#include "chrome/browser/policy/configuration_policy_store_interface.h"
15#include "chrome/browser/policy/configuration_policy_provider.h"
16
17namespace base {
18namespace win {
19class RegKey;
20}  // namespace win
21}  // namespace base
22
23namespace policy {
24
25// An implementation of |ConfigurationPolicyProvider| using the
26// mechanism provided by Windows Groups Policy. Policy decisions are
27// stored as values in a special section of the Windows Registry.
28// On a managed machine in a domain, this portion of the registry is
29// periodically updated by the Windows Group Policy machinery to contain
30// the latest version of the policy set by administrators.
31class ConfigurationPolicyProviderWin
32    : public ConfigurationPolicyProvider,
33      public base::SupportsWeakPtr<ConfigurationPolicyProviderWin> {
34 public:
35  // Keeps watch on Windows Group Policy notification event to trigger a policy
36  // reload when Group Policy changes. This class is reference counted to
37  // facilitate timer-based reloads through the message loop. It is not safe to
38  // access GroupPolicyChangeWatcher concurrently from multiple threads.
39  class GroupPolicyChangeWatcher
40      : public base::ObjectWatcher::Delegate,
41        public MessageLoop::DestructionObserver,
42        public base::RefCountedThreadSafe<GroupPolicyChangeWatcher> {
43   public:
44    GroupPolicyChangeWatcher(
45        base::WeakPtr<ConfigurationPolicyProviderWin> provider,
46        int reload_interval_minutes);
47    virtual ~GroupPolicyChangeWatcher();
48
49    // Start watching.
50    void Start();
51
52    // Stop any pending watch activity in order to allow for timely shutdown.
53    void Stop();
54
55   private:
56    // Updates the watchers and schedules the reload task if appropriate.
57    void SetupWatches();
58
59    // Post a reload notification and update the watch machinery.
60    void Reload();
61
62    // Called for timer-based refresh from the message loop.
63    void ReloadFromTask();
64
65    // ObjectWatcher::Delegate implementation:
66    virtual void OnObjectSignaled(HANDLE object);
67
68    // MessageLoop::DestructionObserver implementation:
69    virtual void WillDestroyCurrentMessageLoop();
70
71    base::WeakPtr<ConfigurationPolicyProviderWin> provider_;
72    base::WaitableEvent user_policy_changed_event_;
73    base::WaitableEvent machine_policy_changed_event_;
74    base::ObjectWatcher user_policy_watcher_;
75    base::ObjectWatcher machine_policy_watcher_;
76    bool user_policy_watcher_failed_;
77    bool machine_policy_watcher_failed_;
78
79    // Period to schedule the reload task at.
80    int reload_interval_minutes_;
81
82    // A reference to a delayed task for timer-based reloading.
83    CancelableTask* reload_task_;
84  };
85
86  explicit ConfigurationPolicyProviderWin(
87      const PolicyDefinitionList* policy_list);
88  virtual ~ConfigurationPolicyProviderWin();
89
90  // ConfigurationPolicyProvider method overrides:
91  virtual bool Provide(ConfigurationPolicyStoreInterface* store);
92
93 protected:
94  // The sub key path for Chromium's Group Policy information in the
95  // Windows registry.
96  static const wchar_t kPolicyRegistrySubKey[];
97
98 private:
99  scoped_refptr<GroupPolicyChangeWatcher> watcher_;
100
101  // Methods to perform type-specific policy lookups in the registry.
102  // HKLM is checked first, then HKCU.
103
104  // Reads a string registry value |name| at the specified |key| and puts the
105  // resulting string in |result|.
106  bool GetRegistryPolicyString(const string16& name, string16* result) const;
107  // Gets a list value contained under |key| one level below the policy root.
108  bool GetRegistryPolicyStringList(const string16& key,
109                                   ListValue* result) const;
110  bool GetRegistryPolicyBoolean(const string16& value_name,
111                                bool* result) const;
112  bool GetRegistryPolicyInteger(const string16& value_name,
113                                uint32* result) const;
114};
115
116}  // namespace policy
117
118#endif  // CHROME_BROWSER_POLICY_CONFIGURATION_POLICY_PROVIDER_WIN_H_
119