1 // 2 // Copyright (C) 2012 The Android Open Source Project 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // http://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 17 #ifndef UPDATE_ENGINE_COMMON_PREFS_H_ 18 #define UPDATE_ENGINE_COMMON_PREFS_H_ 19 20 #include <map> 21 #include <string> 22 #include <vector> 23 24 #include <base/files/file_path.h> 25 26 #include "gtest/gtest_prod.h" // for FRIEND_TEST 27 #include "update_engine/common/prefs_interface.h" 28 29 namespace chromeos_update_engine { 30 31 // Implements a preference store by storing the value associated with a key 32 // in a given storage passed during construction. 33 class PrefsBase : public PrefsInterface { 34 public: 35 // Storage interface used to set and retrieve keys. 36 class StorageInterface { 37 public: 38 StorageInterface() = default; 39 virtual ~StorageInterface() = default; 40 41 // Get the key named |key| and store its value in the referenced |value|. 42 // Returns whether the operation succeeded. 43 virtual bool GetKey(const std::string& key, std::string* value) const = 0; 44 45 // Set the value of the key named |key| to |value| regardless of the 46 // previous value. Returns whether the operation succeeded. 47 virtual bool SetKey(const std::string& key, const std::string& value) = 0; 48 49 // Returns whether the key named |key| exists. 50 virtual bool KeyExists(const std::string& key) const = 0; 51 52 // Deletes the value associated with the key name |key|. Returns whether the 53 // key was deleted. 54 virtual bool DeleteKey(const std::string& key) = 0; 55 56 private: 57 DISALLOW_COPY_AND_ASSIGN(StorageInterface); 58 }; 59 60 explicit PrefsBase(StorageInterface* storage) : storage_(storage) {} 61 62 // PrefsInterface methods. 63 bool GetString(const std::string& key, std::string* value) const override; 64 bool SetString(const std::string& key, const std::string& value) override; 65 bool GetInt64(const std::string& key, int64_t* value) const override; 66 bool SetInt64(const std::string& key, const int64_t value) override; 67 bool GetBoolean(const std::string& key, bool* value) const override; 68 bool SetBoolean(const std::string& key, const bool value) override; 69 70 bool Exists(const std::string& key) const override; 71 bool Delete(const std::string& key) override; 72 73 void AddObserver(const std::string& key, 74 ObserverInterface* observer) override; 75 void RemoveObserver(const std::string& key, 76 ObserverInterface* observer) override; 77 78 private: 79 // The registered observers watching for changes. 80 std::map<std::string, std::vector<ObserverInterface*>> observers_; 81 82 // The concrete implementation of the storage used for the keys. 83 StorageInterface* storage_; 84 85 DISALLOW_COPY_AND_ASSIGN(PrefsBase); 86 }; 87 88 // Implements a preference store by storing the value associated with 89 // a key in a separate file named after the key under a preference 90 // store directory. 91 92 class Prefs : public PrefsBase { 93 public: 94 Prefs() : PrefsBase(&file_storage_) {} 95 96 // Initializes the store by associating this object with |prefs_dir| 97 // as the preference store directory. Returns true on success, false 98 // otherwise. 99 bool Init(const base::FilePath& prefs_dir); 100 101 private: 102 FRIEND_TEST(PrefsTest, GetFileNameForKey); 103 FRIEND_TEST(PrefsTest, GetFileNameForKeyBadCharacter); 104 FRIEND_TEST(PrefsTest, GetFileNameForKeyEmpty); 105 106 class FileStorage : public PrefsBase::StorageInterface { 107 public: 108 FileStorage() = default; 109 110 bool Init(const base::FilePath& prefs_dir); 111 112 // PrefsBase::StorageInterface overrides. 113 bool GetKey(const std::string& key, std::string* value) const override; 114 bool SetKey(const std::string& key, const std::string& value) override; 115 bool KeyExists(const std::string& key) const override; 116 bool DeleteKey(const std::string& key) override; 117 118 private: 119 FRIEND_TEST(PrefsTest, GetFileNameForKey); 120 FRIEND_TEST(PrefsTest, GetFileNameForKeyBadCharacter); 121 FRIEND_TEST(PrefsTest, GetFileNameForKeyEmpty); 122 123 // Sets |filename| to the full path to the file containing the data 124 // associated with |key|. Returns true on success, false otherwise. 125 bool GetFileNameForKey(const std::string& key, 126 base::FilePath* filename) const; 127 128 // Preference store directory. 129 base::FilePath prefs_dir_; 130 }; 131 132 // The concrete file storage implementation. 133 FileStorage file_storage_; 134 135 DISALLOW_COPY_AND_ASSIGN(Prefs); 136 }; 137 138 // Implements a preference store in memory. The stored values are lost when the 139 // object is destroyed. 140 141 class MemoryPrefs : public PrefsBase { 142 public: 143 MemoryPrefs() : PrefsBase(&mem_storage_) {} 144 145 private: 146 class MemoryStorage : public PrefsBase::StorageInterface { 147 public: 148 MemoryStorage() = default; 149 150 // PrefsBase::StorageInterface overrides. 151 bool GetKey(const std::string& key, std::string* value) const override; 152 bool SetKey(const std::string& key, const std::string& value) override; 153 bool KeyExists(const std::string& key) const override; 154 bool DeleteKey(const std::string& key) override; 155 156 private: 157 // The std::map holding the values in memory. 158 std::map<std::string, std::string> values_; 159 }; 160 161 // The concrete memory storage implementation. 162 MemoryStorage mem_storage_; 163 164 DISALLOW_COPY_AND_ASSIGN(MemoryPrefs); 165 }; 166 } // namespace chromeos_update_engine 167 168 #endif // UPDATE_ENGINE_COMMON_PREFS_H_ 169
