1 /* 2 * Copyright (C) 2016 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 #pragma once 18 19 #include <sys/cdefs.h> 20 21 #include <chrono> 22 #include <limits> 23 #include <string> 24 25 namespace android { 26 namespace base { 27 28 // Returns the current value of the system property `key`, 29 // or `default_value` if the property is empty or doesn't exist. 30 std::string GetProperty(const std::string& key, const std::string& default_value); 31 32 // Returns true if the system property `key` has the value "1", "y", "yes", "on", or "true", 33 // false for "0", "n", "no", "off", or "false", or `default_value` otherwise. 34 bool GetBoolProperty(const std::string& key, bool default_value); 35 36 // Returns the signed integer corresponding to the system property `key`. 37 // If the property is empty, doesn't exist, doesn't have an integer value, or is outside 38 // the optional bounds, returns `default_value`. 39 template <typename T> T GetIntProperty(const std::string& key, 40 T default_value, 41 T min = std::numeric_limits<T>::min(), 42 T max = std::numeric_limits<T>::max()); 43 44 // Returns the unsigned integer corresponding to the system property `key`. 45 // If the property is empty, doesn't exist, doesn't have an integer value, or is outside 46 // the optional bound, returns `default_value`. 47 template <typename T> T GetUintProperty(const std::string& key, 48 T default_value, 49 T max = std::numeric_limits<T>::max()); 50 51 // Sets the system property `key` to `value`. 52 // Note that system property setting is inherently asynchronous so a return value of `true` 53 // isn't particularly meaningful, and immediately reading back the value won't necessarily 54 // tell you whether or not your call succeeded. A `false` return value definitely means failure. 55 bool SetProperty(const std::string& key, const std::string& value); 56 57 // Waits for the system property `key` to have the value `expected_value`. 58 // Times out after `relative_timeout`. 59 // Returns true on success, false on timeout. 60 #if defined(__BIONIC__) 61 bool WaitForProperty(const std::string& key, const std::string& expected_value, 62 std::chrono::milliseconds relative_timeout = std::chrono::milliseconds::max()); 63 #endif 64 65 // Waits for the system property `key` to be created. 66 // Times out after `relative_timeout`. 67 // Returns true on success, false on timeout. 68 #if defined(__BIONIC__) 69 bool WaitForPropertyCreation(const std::string& key, std::chrono::milliseconds relative_timeout = 70 std::chrono::milliseconds::max()); 71 #endif 72 73 } // namespace base 74 } // namespace android 75