Adds basic group policy support. Resubmitting r33093 with a new unit test....

chrome/browser/group_policy.h

+// Copyright (c) 2009 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.
+//
+// A central repository for definitions relating to Group Policy.
+
+#ifndef CHROME_BROWSER_GROUP_POLICY_H_
+#define CHROME_BROWSER_GROUP_POLICY_H_
+
+#include <windows.h>
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "base/values.h"
+#include "build/build_config.h"
+
+// Each policy:
+//   - has a name; this is used to refer to the policy for testing in code.
+//   - has a type; the type of a policy decides what sort of value a policy
+//         lookup returns as well as how the policy handles it when it is
+//         defined both in user and machine policy.
+//         Policy types include:
+//           # Flag; a boolean flag, if either machine or user instance
+//               of the flag is nonzero, then the flag is set. Otherwise,
+//               whether both or either are nonexistent or zero, the flag
+//               is unset.
+//           # Number; a DWORD number.
+//           # String; a character string.
+//           # String List; an unordered list of strings.
+//   - belongs to class; Each policy is either a machine or a user policy
+//          or both.
+//         Policies that belong to the user class are stored under HKCU, while
+//         those of machine class are stored under HKLM. Policies of class both
+//         belong in both places. For such policies, the meaning of
+//         conflicting settings is determined by the type of the policy.
+//   - has a registry key; This is a path from the toplevel key or keys that
+//         the policy class implies.
+//   - has a value name; Depending on the type of the policy, this is the name
+//         of the value or the subkey that contains the policy flag or value.
+//   - has a display name; this is the name displayed to the administrator in
+//         the group policy editor.
+//   - has a help string; this is the help string displayed to the administrator
+//         in the group policy editor.
+
+namespace group_policy {
+
+// Get the root registry location of group policy settings.
+bool GetPolicySettingsRootKey(std::wstring* policy_key);
+
+// Check if the machine has any group policy settings.
+bool HasGroupPolicySettings();
+
+// True if the machine has group policy settings in HKCU.
+bool HasHkcuSettings();
+
+// True if the machine has group policy settings in HKLM.
+bool HasHklmSettings();
+
+// This specifies how to combine the user and machine keys for the
+// policy setting; some are only applicable to certain data types
+// and/or certain storage types.  Add more as needed.
+enum PolicyCombine {
+  POLICYCOMBINE_PREFERMACHINE,    // HKLM policy takes priority.
+  POLICYCOMBINE_PREFERUSER,       // HKCU policy takes priority.
+  POLICYCOMBINE_CONCATENATE,      // Concatenate both policies.
+  POLICYCOMBINE_LOGICALOR,        // Logical OR of both keys.
+};
+
+// This specifies how the policy setting is stored in the registry.
+// Add more as needed.
+enum PolicyStorage {
+  POLICYSTORAGE_SINGLEVALUE,    // Policy is a single registry value.
+  POLICYSTORAGE_CONCATSUBKEYS,  // Policy is set of subkeys of specified key.
+};
+
+// Class that represents a group policy setting.  Encapsulates the lookup
+// from both policy sections of the registry, as well as the method for
+// combining values in the two policy sections.
+class SettingBase {
+ public:
+  SettingBase(const wchar_t* regkey,
+              const wchar_t* regvalue,
+              PolicyStorage storage,
+              PolicyCombine combine) : regkey_(regkey),
+                  regvalue_(regvalue), storage_(storage),
+                  combine_(combine) {
+    // Both parameters are required.  Either can be empty (but not both.)
+    DCHECK(regkey != NULL);
+    DCHECK(regvalue != NULL);
+    DCHECK(regkey[0] != L'\0' || regvalue[0] != L'\0');
+
+    // If storage is POLICYSTORAGE_CONCATSUBKEYS, regvalue should be empty.
+    DCHECK((storage != POLICYSTORAGE_CONCATSUBKEYS) ||
+           regvalue[0] == L'\0');
+  }
+
+  // Returns whether this setting is controlled by group policy;
+  // indicates whether this value is set somewhere in the registry.
+  bool IsPolicyControlled() const;
+
+ protected:
+  // These accessors are protected and then individually exposed in a
+  // templated base class.  That lets the compiler enforce that the code
+  // using a policy is using the appropriate data type.
+  HRESULT GetSetting(std::wstring* value, bool* found) const;
+  HRESULT GetSetting(ListValue* list, bool* found) const;
+  HRESULT GetSetting(DWORD* value, bool* found) const;
+  HRESULT GetSetting(bool* value, bool* found) const;
+  const wchar_t* regkey_;
+  const wchar_t* regvalue_;
+
+ private:
+  // Private helper accessors for pulling individual registry keys
+  HRESULT GetSettingFromTree(HKEY tree, std::wstring* value, bool* found) const;
+  HRESULT GetSettingFromTree(HKEY tree, ListValue* value, bool* found) const;
+  HRESULT GetSettingFromTree(HKEY tree, DWORD* value, bool* found) const;
+  HRESULT GetSettingFromTree(HKEY tree, bool* value, bool* found) const;
+
+  PolicyStorage storage_;
+  PolicyCombine combine_;
+};
+
+// Templated class to provide type-safe access to policy setting.
+template <typename T>
+class Setting : public SettingBase {
+ public:
+  Setting(const wchar_t* regkey,
+          const wchar_t* regvalue,
+          PolicyStorage storage,
+          PolicyCombine combine) :
+      SettingBase(regkey, regvalue, storage, combine) {
+  }
+
+  HRESULT GetSetting(T* value, bool* found) const {
+    DCHECK(found);
+    DCHECK(value);
+    DCHECK(regvalue_ != NULL && regkey_ != NULL) <<
+        "Setting not initialized - don't call at static init time!";
+
+    *found = false;
+
+    if (!HasGroupPolicySettings())
+      return S_OK;
+
+    return SettingBase::GetSetting(value, found);
+  }
+};
+
+// Is option set, default is 'no'.
+bool IsBoolOptionSet(const Setting<bool>& setting);
+
+// Helper function for appending all of one ListValue to another.
+void AppendAll(ListValue* target, ListValue* source);
+
+}  // namespace
+
+#endif  // CHROME_BROWSER_GROUP_POLICY_H_
+