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//
// 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 <string_view>
#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 given storage passed during construction.
class PrefsBase : public PrefsInterface {
public:
// Storage interface used to set and retrieve keys.
class StorageInterface {
public:
StorageInterface() = default;
virtual ~StorageInterface() = default;
// Get the key named |key| and store its value in the referenced |value|.
// Returns whether the operation succeeded.
virtual bool GetKey(const std::string& key, std::string* value) const = 0;
// Get the keys stored within the namespace. If there are no keys in the
// namespace, |keys| will be empty. Returns whether the operation succeeded.
virtual bool GetSubKeys(const std::string& ns,
std::vector<std::string>* keys) const = 0;
// Set the value of the key named |key| to |value| regardless of the
// previous value. Returns whether the operation succeeded.
virtual bool SetKey(const std::string& key, std::string_view value) = 0;
// Returns whether the key named |key| exists.
virtual bool KeyExists(const std::string& key) const = 0;
// Deletes the value associated with the key name |key|. Returns whether the
// key was deleted.
virtual bool DeleteKey(const std::string& key) = 0;
private:
DISALLOW_COPY_AND_ASSIGN(StorageInterface);
};
explicit PrefsBase(StorageInterface* storage) : storage_(storage) {}
// PrefsInterface methods.
bool GetString(const std::string& key, std::string* value) const override;
bool SetString(const std::string& key, std::string_view 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;
bool Delete(const std::string& pref_key,
const std::vector<std::string>& nss) override;
bool GetSubKeys(const std::string& ns,
std::vector<std::string>* keys) const override;
void AddObserver(const std::string& key,
ObserverInterface* observer) override;
void RemoveObserver(const std::string& key,
ObserverInterface* observer) override;
private:
// The registered observers watching for changes.
std::map<std::string, std::vector<ObserverInterface*>> observers_;
// The concrete implementation of the storage used for the keys.
StorageInterface* storage_;
DISALLOW_COPY_AND_ASSIGN(PrefsBase);
};
// 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 PrefsBase {
public:
Prefs() : PrefsBase(&file_storage_) {}
// 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);
private:
FRIEND_TEST(PrefsTest, GetFileNameForKey);
FRIEND_TEST(PrefsTest, GetFileNameForKeyBadCharacter);
FRIEND_TEST(PrefsTest, GetFileNameForKeyEmpty);
class FileStorage : public PrefsBase::StorageInterface {
public:
FileStorage() = default;
bool Init(const base::FilePath& prefs_dir);
// PrefsBase::StorageInterface overrides.
bool GetKey(const std::string& key, std::string* value) const override;
bool GetSubKeys(const std::string& ns,
std::vector<std::string>* keys) const override;
bool SetKey(const std::string& key, std::string_view value) override;
bool KeyExists(const std::string& key) const override;
bool DeleteKey(const std::string& key) 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 concrete file storage implementation.
FileStorage file_storage_;
DISALLOW_COPY_AND_ASSIGN(Prefs);
};
// Implements a preference store in memory. The stored values are lost when the
// object is destroyed.
class MemoryPrefs : public PrefsBase {
public:
MemoryPrefs() : PrefsBase(&mem_storage_) {}
private:
class MemoryStorage : public PrefsBase::StorageInterface {
public:
MemoryStorage() = default;
// PrefsBase::StorageInterface overrides.
bool GetKey(const std::string& key, std::string* value) const override;
bool GetSubKeys(const std::string& ns,
std::vector<std::string>* keys) const override;
bool SetKey(const std::string& key, std::string_view value) override;
bool KeyExists(const std::string& key) const override;
bool DeleteKey(const std::string& key) override;
private:
// The std::map holding the values in memory.
std::map<std::string, std::string> values_;
};
// The concrete memory storage implementation.
MemoryStorage mem_storage_;
DISALLOW_COPY_AND_ASSIGN(MemoryPrefs);
};
} // namespace chromeos_update_engine
#endif // UPDATE_ENGINE_COMMON_PREFS_H_