1 /*
2 * Copyright (C) 2022 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 #include "interprocess_fifo.h"
18
19 #include <android-base/logging.h>
20
21 #include <unistd.h>
22
23 using ::android::base::ErrnoError;
24 using ::android::base::Error;
25 using ::android::base::Result;
26
27 namespace android {
28 namespace init {
29
InterprocessFifo()30 InterprocessFifo::InterprocessFifo() noexcept : fds_({-1, -1}) {}
31
InterprocessFifo(InterprocessFifo && orig)32 InterprocessFifo::InterprocessFifo(InterprocessFifo&& orig) noexcept : fds_({-1, -1}) {
33 std::swap(fds_, orig.fds_);
34 }
35
~InterprocessFifo()36 InterprocessFifo::~InterprocessFifo() noexcept {
37 Close();
38 }
39
CloseFd(int & fd)40 void InterprocessFifo::CloseFd(int& fd) noexcept {
41 if (fd >= 0) {
42 close(fd);
43 fd = -1;
44 }
45 }
46
CloseReadFd()47 void InterprocessFifo::CloseReadFd() noexcept {
48 CloseFd(fds_[0]);
49 }
50
CloseWriteFd()51 void InterprocessFifo::CloseWriteFd() noexcept {
52 CloseFd(fds_[1]);
53 }
54
Close()55 void InterprocessFifo::Close() noexcept {
56 CloseReadFd();
57 CloseWriteFd();
58 }
59
Initialize()60 Result<void> InterprocessFifo::Initialize() noexcept {
61 if (fds_[0] >= 0) {
62 return Error() << "already initialized";
63 }
64 if (pipe(fds_.data()) < 0) { // NOLINT(android-cloexec-pipe)
65 return ErrnoError() << "pipe()";
66 }
67 return {};
68 }
69
Read()70 Result<uint8_t> InterprocessFifo::Read() noexcept {
71 uint8_t byte;
72 ssize_t count = read(fds_[0], &byte, 1);
73 if (count < 0) {
74 return ErrnoError() << "read()";
75 }
76 if (count == 0) {
77 return Error() << "read() EOF";
78 }
79 DCHECK_EQ(count, 1);
80 return byte;
81 }
82
Write(uint8_t byte)83 Result<void> InterprocessFifo::Write(uint8_t byte) noexcept {
84 ssize_t written = write(fds_[1], &byte, 1);
85 if (written < 0) {
86 return ErrnoError() << "write()";
87 }
88 if (written == 0) {
89 return Error() << "write() EOF";
90 }
91 DCHECK_EQ(written, 1);
92 return {};
93 }
94
95 } // namespace init
96 } // namespace android
97