1 // Copyright 2022 Google LLC
2 //
3 // Redistribution and use in source and binary forms, with or without
4 // modification, are permitted provided that the following conditions are
5 // met:
6 //
7 // * Redistributions of source code must retain the above copyright
8 // notice, this list of conditions and the following disclaimer.
9 // * Redistributions in binary form must reproduce the above
10 // copyright notice, this list of conditions and the following disclaimer
11 // in the documentation and/or other materials provided with the
12 // distribution.
13 // * Neither the name of Google LLC nor the names of its
14 // contributors may be used to endorse or promote products derived from
15 // this software without specific prior written permission.
16 //
17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
29 #ifdef HAVE_CONFIG_H
30 #include <config.h> // Must come first
31 #endif
32
33 #include "common/linux/scoped_pipe.h"
34
35 #include <unistd.h>
36
37 #include "common/linux/eintr_wrapper.h"
38
39 namespace google_breakpad {
40
ScopedPipe()41 ScopedPipe::ScopedPipe() {
42 fds_[0] = -1;
43 fds_[1] = -1;
44 }
45
~ScopedPipe()46 ScopedPipe::~ScopedPipe() {
47 CloseReadFd();
48 CloseWriteFd();
49 }
50
Init()51 bool ScopedPipe::Init() {
52 return pipe(fds_) == 0;
53 }
54
CloseReadFd()55 void ScopedPipe::CloseReadFd() {
56 if (fds_[0] != -1) {
57 close(fds_[0]);
58 fds_[0] = -1;
59 }
60 }
61
CloseWriteFd()62 void ScopedPipe::CloseWriteFd() {
63 if (fds_[1] != -1) {
64 close(fds_[1]);
65 fds_[1] = -1;
66 }
67 }
68
ReadLine(std::string & line)69 bool ScopedPipe::ReadLine(std::string& line) {
70 // Simple buffered file read. `read_buffer_` stores previously read bytes, and
71 // we either return a line from this buffer, or we append blocks of read bytes
72 // to the buffer until we have a complete line.
73 size_t eol_index = read_buffer_.find('\n');
74
75 // While we don't have a full line, and read pipe is valid.
76 while (eol_index == std::string::npos && GetReadFd() != -1) {
77 // Read a block of 128 bytes from the read pipe.
78 char read_buf[128];
79 ssize_t read_len = HANDLE_EINTR(
80 read(GetReadFd(), read_buf, sizeof(read_buf)));
81 if (read_len <= 0) {
82 // Pipe error, or pipe has been closed.
83 CloseReadFd();
84 break;
85 }
86
87 // Append the block, and check if we have a full line now.
88 read_buffer_.append(read_buf, read_len);
89 eol_index = read_buffer_.find('\n');
90 }
91
92 if (eol_index != std::string::npos) {
93 // We have a full line to output.
94 line = read_buffer_.substr(0, eol_index);
95 if (eol_index < read_buffer_.size()) {
96 read_buffer_ = read_buffer_.substr(eol_index + 1);
97 } else {
98 read_buffer_ = "";
99 }
100
101 return true;
102 }
103
104 if (read_buffer_.size()) {
105 // We don't have a full line to output, but we can only reach here if the
106 // pipe has closed and there are some bytes left at the end, so we should
107 // return those bytes.
108 line = std::move(read_buffer_);
109 read_buffer_ = "";
110
111 return true;
112 }
113
114 // We don't have any buffered data left, and the pipe has closed.
115 return false;
116 }
117
Dup2WriteFd(int new_fd) const118 int ScopedPipe::Dup2WriteFd(int new_fd) const {
119 return dup2(fds_[1], new_fd);
120 }
121
WriteForTesting(const void * bytes,size_t bytes_len)122 bool ScopedPipe::WriteForTesting(const void* bytes, size_t bytes_len) {
123 ssize_t r = HANDLE_EINTR(write(GetWriteFd(), bytes, bytes_len));
124 if (r != static_cast<ssize_t>(bytes_len)) {
125 CloseWriteFd();
126 return false;
127 }
128
129 return true;
130 }
131
132 } // namespace google_breakpad
133