xref: /aosp_15_r20/external/google-breakpad/src/common/linux/scoped_pipe.cc (revision 9712c20fc9bbfbac4935993a2ca0b3958c5adad2)
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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