1 /*
2 * Copyright (C) 2017 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 "PipeRelay.h"
18
19 #include <sys/select.h>
20 #include <sys/time.h>
21 #include <sys/types.h>
22 #include <unistd.h>
23
24 #include <atomic>
25
26 #include <android-base/logging.h>
27 #include <utils/Thread.h>
28
29 namespace android {
30 namespace lshal {
31
32 static constexpr struct timeval READ_TIMEOUT { .tv_sec = 1, .tv_usec = 0 };
33
34 struct PipeRelay::RelayThread : public Thread {
35 explicit RelayThread(int fd, std::ostream &os);
36
37 bool threadLoop() override;
38 void setFinished();
39
40 private:
41 int mFd;
42 std::ostream &mOutStream;
43
44 // If we were to use requestExit() and exitPending() instead, threadLoop()
45 // may not run at all by the time ~PipeRelay is called (i.e. debug() has
46 // returned from HAL). By using our own flag, we ensure that select() and
47 // read() are executed until data are drained.
48 std::atomic_bool mFinished;
49
50 DISALLOW_COPY_AND_ASSIGN(RelayThread);
51 };
52
53 ////////////////////////////////////////////////////////////////////////////////
54
RelayThread(int fd,std::ostream & os)55 PipeRelay::RelayThread::RelayThread(int fd, std::ostream &os)
56 : mFd(fd), mOutStream(os), mFinished(false) {}
57
threadLoop()58 bool PipeRelay::RelayThread::threadLoop() {
59 char buffer[1024];
60
61 fd_set set;
62 FD_ZERO(&set);
63 FD_SET(mFd, &set);
64
65 struct timeval timeout = READ_TIMEOUT;
66
67 int res = TEMP_FAILURE_RETRY(select(mFd + 1, &set, nullptr, nullptr, &timeout));
68 if (res < 0) {
69 PLOG(INFO) << "select() failed";
70 return false;
71 }
72
73 if (res == 0 || !FD_ISSET(mFd, &set)) {
74 if (mFinished) {
75 LOG(WARNING) << "debug: timeout reading from pipe, output may be truncated.";
76 return false;
77 }
78 // timeout, but debug() has not returned, so wait for HAL to finish.
79 return true;
80 }
81
82 // FD_ISSET(mFd, &set) == true. Data available, start reading
83 ssize_t n = TEMP_FAILURE_RETRY(read(mFd, buffer, sizeof(buffer)));
84
85 if (n < 0) {
86 PLOG(ERROR) << "read() failed";
87 }
88
89 if (n <= 0) {
90 return false;
91 }
92
93 mOutStream.write(buffer, n);
94
95 return true;
96 }
97
setFinished()98 void PipeRelay::RelayThread::setFinished() {
99 mFinished = true;
100 }
101
102 ////////////////////////////////////////////////////////////////////////////////
103
PipeRelay(std::ostream & os)104 PipeRelay::PipeRelay(std::ostream &os)
105 : mInitCheck(NO_INIT) {
106 int res = pipe(mFds);
107
108 if (res < 0) {
109 mInitCheck = -errno;
110 return;
111 }
112
113 mThread = new RelayThread(mFds[0], os);
114 mInitCheck = mThread->run("RelayThread");
115 }
116
CloseFd(int * fd)117 void PipeRelay::CloseFd(int *fd) {
118 if (*fd >= 0) {
119 close(*fd);
120 *fd = -1;
121 }
122 }
123
~PipeRelay()124 PipeRelay::~PipeRelay() {
125 CloseFd(&mFds[1]);
126
127 if (mThread != nullptr) {
128 mThread->setFinished();
129 mThread->join();
130 mThread.clear();
131 }
132
133 CloseFd(&mFds[0]);
134 }
135
initCheck() const136 status_t PipeRelay::initCheck() const {
137 return mInitCheck;
138 }
139
fd() const140 int PipeRelay::fd() const {
141 return mFds[1];
142 }
143
144 } // namespace lshal
145 } // namespace android
146