os.h revision b8f8f6ab38fe147fa7aed5cdd9f9ce0e5a3a2e2f
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#ifndef OS_H_ 18#define OS_H_ 19 20#include <time.h> 21 22#include <cstdint> 23#include <memory> 24#include <tuple> 25#include <utility> 26 27#include "android-base/macros.h" 28 29#include "wifilogd/raw_os.h" 30 31namespace android { 32namespace wifilogd { 33 34// Abstracts operating system calls. 35// 36// There are three reasons we want to abstract OS calls: 37// 1. Allow tests to run hermetically. 38// 2. Verify that the application logic invokes the OS calls as expected. 39// 3. Provide interfaces that as easier to use, than the underlying OS calls. 40class Os { 41 public: 42 using Errno = int; 43 44 struct Timestamp { 45 uint32_t secs; // Sufficient through 2100. 46 uint32_t nsecs; 47 }; 48 49 // Constructs an Os instance. 50 Os(); 51 52 // Constructs an Os instance, with the caller-provided RawOs. This method 53 // allows tests to provide a MockRawOs. 54 explicit Os(std::unique_ptr<RawOs> raw_os); 55 56 virtual ~Os(); 57 58 // Returns the current time, as reported by the clock with |clock_id|. 59 virtual Timestamp GetTimestamp(clockid_t clock_id) const; 60 61 // Writes |buflen| bytes from |buf| to |fd|. Returns the number of bytes 62 // written, and the result of the operation (0 for success, |errno| 63 // otherwise). 64 // 65 // Notes: 66 // - |buflen| may not exceed the maximal value for ssize_t. 67 // - The returned size_t will not exceed |buflen|. 68 virtual std::tuple<size_t, Errno> Write(int fd, const void* buf, 69 size_t buflen); 70 71 private: 72 const std::unique_ptr<RawOs> raw_os_; 73 74 DISALLOW_COPY_AND_ASSIGN(Os); 75}; 76 77} // namespace wifilogd 78} // namespace android 79 80#endif // OS_H_ 81