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/poll.h>
20 #include <sys/types.h>
21 #include <unistd.h>
22
23 #include <chrono>
24 #include <optional>
25
26 #include <android-base/unique_fd.h>
27
28 using android::base::borrowed_fd;
29 using android::base::Result;
30 using android::base::unique_fd;
31 using std::chrono_literals::operator""ms;
32
33 namespace android {
34 namespace lshal {
create(std::ostream & os,const NullableOStream<std::ostream> & err,const std::string & fqName)35 Result<std::unique_ptr<PipeRelay>> PipeRelay::create(std::ostream& os,
36 const NullableOStream<std::ostream>& err,
37 const std::string& fqName) {
38 auto pipeRelay = std::unique_ptr<PipeRelay>(new PipeRelay());
39 unique_fd rfd;
40 if (!android::base::Pipe(&rfd, &pipeRelay->mWrite)) {
41 return android::base::ErrnoError() << "pipe()";
42 }
43 // Workaround for b/111997867: need a separate FD trigger because rfd can't receive POLLHUP
44 // when the write end is closed after the write end was sent through hwbinder.
45 unique_fd rfdTrigger;
46 if (!android::base::Pipe(&rfdTrigger, &pipeRelay->mWriteTrigger)) {
47 return android::base::ErrnoError() << "pipe() for trigger";
48 }
49 pipeRelay->mThread =
50 std::make_unique<std::thread>(&PipeRelay::thread, std::move(rfd), std::move(rfdTrigger),
51 &os, &err, fqName);
52 return pipeRelay;
53 }
54
thread(unique_fd rfd,unique_fd rfdTrigger,std::ostream * out,const NullableOStream<std::ostream> * err,std::string fqName)55 void PipeRelay::thread(unique_fd rfd, unique_fd rfdTrigger, std::ostream* out,
56 const NullableOStream<std::ostream>* err, std::string fqName) {
57 while (true) {
58 pollfd pfd[2];
59 pfd[0] = {.fd = rfd.get(), .events = POLLIN};
60 pfd[1] = {.fd = rfdTrigger.get(), .events = 0};
61
62 int pollRes = poll(pfd, arraysize(pfd), -1 /* infinite timeout */);
63 if (pollRes < 0) {
64 int savedErrno = errno;
65 (*err) << "debug " << fqName << ": poll() failed: " << strerror(savedErrno)
66 << std::endl;
67 break;
68 }
69
70 if (pfd[0].revents & POLLIN) {
71 char buffer[1024];
72 ssize_t n = TEMP_FAILURE_RETRY(read(rfd.get(), buffer, sizeof(buffer)));
73 if (n < 0) {
74 int savedErrno = errno;
75 (*err) << "debug " << fqName << ": read() failed: " << strerror(savedErrno)
76 << std::endl;
77 break;
78 }
79 if (n == 0) {
80 (*err) << "Warning: debug " << fqName << ": poll() indicates POLLIN but no data"
81 << std::endl;
82 continue;
83 }
84 out->write(buffer, n);
85 continue;
86 }
87 if (pfd[0].revents & POLLHUP) {
88 break;
89 }
90 if (pfd[1].revents & POLLHUP) {
91 // ~PipeRelay is called on the main thread. |mWrite| has been flushed and closed.
92 // Ensure that our read end of the pipe doesn't have pending data, then exit.
93 if ((pfd[0].revents & POLLIN) == 0) {
94 break;
95 }
96 }
97 }
98 }
99
~PipeRelay()100 PipeRelay::~PipeRelay() {
101 mWrite.reset();
102 mWriteTrigger.reset();
103 if (mThread != nullptr && mThread->joinable()) {
104 mThread->join();
105 }
106 }
107
108 } // namespace lshal
109 } // namespace android
110