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 <string>
25#include <tuple>
26#include <utility>
27
28#include "android-base/macros.h"
29
30#include "wifilogd/local_utils.h"
31#include "wifilogd/raw_os.h"
32
33namespace android {
34namespace wifilogd {
35
36// Abstracts operating system calls.
37//
38// There are three reasons we want to abstract OS calls:
39// 1. Allow tests to run hermetically.
40// 2. Verify that the application logic invokes the OS calls as expected.
41// 3. Provide interfaces that as easier to use, than the underlying OS calls.
42class Os {
43 public:
44  using Errno = int;
45
46  struct Timestamp {
47    uint32_t secs;  // Sufficient through 2100.
48    uint32_t nsecs;
49  };
50
51  static constexpr int kInvalidFd = -1;
52  static constexpr auto kMaxNanos = 999'999'999;
53
54  // Constructs an Os instance.
55  Os();
56
57  // Constructs an Os instance, with the caller-provided RawOs. This method
58  // allows tests to provide a MockRawOs.
59  explicit Os(std::unique_ptr<RawOs> raw_os);
60
61  virtual ~Os();
62
63  // Returns the Android control socket with name |socket_name|. If no such
64  // socket exists, or the init daemon has not provided this process with
65  // access to said socket, returns {kInvalidFd, errno}.
66  virtual std::tuple<int, Errno> GetControlSocket(
67      const std::string& socket_name);
68
69  // Returns the current time, as reported by the clock with |clock_id|.
70  virtual Timestamp GetTimestamp(clockid_t clock_id) const;
71
72  // Suspends execution of this process, for |sleep_time_nsec|. The passed
73  // value must not exceed kMaxNanos.
74  virtual void Nanosleep(uint32_t sleep_time_nsec);
75
76  // Receives a datagram of up to |buflen| from |fd|, writing the data to |buf|.
77  // Returns the size of the datagram, and the result of the operation (0 for
78  // success, |errno| otherwise).
79  //
80  // Notes:
81  // - |buflen| may not exceed the maximal value for ssize_t.
82  // - The call blocks until a datagram is available.
83  // - If the datagram is larger than |buflen|, only |buflen| bytes will
84  //   be received. The returned size_t will, however, reflect the full
85  //   length of the datagram.
86  virtual std::tuple<size_t, Errno> ReceiveDatagram(int fd, NONNULL void* buf,
87                                                    size_t buflen);
88
89  // Writes |buflen| bytes from |buf| to |fd|. Returns the number of bytes
90  // written, and the result of the operation (0 for success, |errno|
91  // otherwise).
92  //
93  // Notes:
94  // - |buflen| may not exceed the maximal value for ssize_t.
95  // - The returned size_t will not exceed |buflen|.
96  virtual std::tuple<size_t, Errno> Write(int fd, NONNULL const void* buf,
97                                          size_t buflen);
98
99 private:
100  const std::unique_ptr<RawOs> raw_os_;
101
102  DISALLOW_COPY_AND_ASSIGN(Os);
103};
104
105}  // namespace wifilogd
106}  // namespace android
107
108#endif  // OS_H_
109