components/user_prefs/tracked/pref_hash_store_impl.h

   1 // Copyright 2013 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 COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_STORE_IMPL_H_
   6 #define COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_STORE_IMPL_H_
   7
   8 #include <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "base/macros.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "components/user_prefs/tracked/pref_hash_calculator.h"
  14 #include "components/user_prefs/tracked/pref_hash_store.h"
  15
  16 class HashStoreContents;
  17 class PrefHashStoreTransaction;
  18
  19 // Implements PrefHashStoreImpl by storing preference hashes in a
  20 // HashStoreContents.
  21 class PrefHashStoreImpl : public PrefHashStore {
  22  public:
  23   enum StoreVersion {
  24     // No hashes have been stored in this PrefHashStore yet.
  25     VERSION_UNINITIALIZED = 0,
  26     // The hashes in this PrefHashStore were stored before the introduction
  27     // of a version number and should be re-initialized.
  28     VERSION_PRE_MIGRATION = 1,
  29     // The hashes in this PrefHashStore were stored using the latest algorithm.
  30     VERSION_LATEST = 2,
  31   };
  32
  33   // Constructs a PrefHashStoreImpl that calculates hashes using
  34   // |seed| and |device_id| and stores them in |contents|.
  35   //
  36   // The same |seed| and |device_id| must be used to load and validate
  37   // previously stored hashes in |contents|.
  38   PrefHashStoreImpl(const std::string& seed,
  39                     const std::string& device_id,
  40                     bool use_super_mac);
  41
  42   ~PrefHashStoreImpl() override;
  43
  44   // Provides an external HashStoreContents implementation to be used.
  45   // BeginTransaction() will ignore |storage| if this is provided.
  46   void set_legacy_hash_store_contents(
  47       scoped_ptr<HashStoreContents> legacy_hash_store_contents);
  48
  49   // Clears the contents of this PrefHashStore. |IsInitialized()| will return
  50   // false after this call.
  51   void Reset();
  52
  53   // PrefHashStore implementation.
  54   scoped_ptr<PrefHashStoreTransaction> BeginTransaction(
  55       scoped_ptr<HashStoreContents> storage) override;
  56
  57  private:
  58   class PrefHashStoreTransactionImpl;
  59
  60   const PrefHashCalculator pref_hash_calculator_;
  61   scoped_ptr<HashStoreContents> legacy_hash_store_contents_;
  62   bool use_super_mac_;
  63
  64   DISALLOW_COPY_AND_ASSIGN(PrefHashStoreImpl);
  65 };
  66
  67 #endif  // COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_STORE_IMPL_H_