common/prefs.h

//
// Copyright (C) 2012 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#ifndef UPDATE_ENGINE_COMMON_PREFS_H_
#define UPDATE_ENGINE_COMMON_PREFS_H_

#include <map>
#include <string>
#include <vector>

#include <base/files/file_path.h>

#include "gtest/gtest_prod.h"  // for FRIEND_TEST
#include "update_engine/common/prefs_interface.h"

namespace chromeos_update_engine {

// Implements a preference store by storing the value associated with
// a key in a separate file named after the key under a preference
// store directory.

class Prefs : public PrefsInterface {
 public:
  Prefs() = default;

  // Initializes the store by associating this object with |prefs_dir|
  // as the preference store directory. Returns true on success, false
  // otherwise.
  bool Init(const base::FilePath& prefs_dir);

  // PrefsInterface methods.
  bool GetString(const std::string& key, std::string* value) const override;
  bool SetString(const std::string& key, const std::string& value) override;
  bool GetInt64(const std::string& key, int64_t* value) const override;
  bool SetInt64(const std::string& key, const int64_t value) override;
  bool GetBoolean(const std::string& key, bool* value) const override;
  bool SetBoolean(const std::string& key, const bool value) override;

  bool Exists(const std::string& key) const override;
  bool Delete(const std::string& key) override;

  void AddObserver(const std::string& key,
                   ObserverInterface* observer) override;
  void RemoveObserver(const std::string& key,
                      ObserverInterface* observer) override;

 private:
  FRIEND_TEST(PrefsTest, GetFileNameForKey);
  FRIEND_TEST(PrefsTest, GetFileNameForKeyBadCharacter);
  FRIEND_TEST(PrefsTest, GetFileNameForKeyEmpty);

  // Sets |filename| to the full path to the file containing the data
  // associated with |key|. Returns true on success, false otherwise.
  bool GetFileNameForKey(const std::string& key,
                         base::FilePath* filename) const;

  // Preference store directory.
  base::FilePath prefs_dir_;

  // The registered observers watching for changes.
  std::map<std::string, std::vector<ObserverInterface*>> observers_;

  DISALLOW_COPY_AND_ASSIGN(Prefs);
};

}  // namespace chromeos_update_engine

#endif  // UPDATE_ENGINE_COMMON_PREFS_H_