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+// Copyright 2022 Google LLC
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Google LLC nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef COMMON_LINUX_SCOPED_PIPE_H_
+#define COMMON_LINUX_SCOPED_PIPE_H_
+
+#include <stdint.h>
+#include <string>
+
+namespace google_breakpad {
+
+// Small RAII wrapper for a pipe pair.
+//
+// Example (both ends of pipe in same process):
+// ScopedPipe tmp;
+// std::string line;
+// if (tmp.Init() && tmp.Write(bytes, bytes_len)) {
+// tmp.CloseWriteFd();
+// while (tmp.ReadLine(&line)) {
+// std::cerr << line << std::endl;
+// }
+// }
+//
+// Example (reading output from a child process):
+// ScopedPipe tmp;
+// if (fork()) {
+// // Parent process, read from the read end of the pipe.
+// std::string line;
+// while (tmp.ReadLine(line)) {
+// // Process output...
+// }
+// // Close read pipe once done processing the output that we wanted, this
+// // should ensure that the child process exits even if we didn't read all
+// // of the output.
+// tmp.CloseReadFd();
+// // Parent process should handle waiting for child to exit here...
+// } else {
+// // Child process, close the read fd and dup the write fd before exec'ing.
+// tmp.CloseReadFd();
+// tmp.Dup2WriteFd(STDOUT_FILENO);
+// tmp.Dup2WriteFd(STDERR_FILENO);
+// execl("some-command", "some-arguments");
+// }
+class ScopedPipe {
+ public:
+ ScopedPipe();
+ ~ScopedPipe();
+
+ // Creates the pipe pair - returns false on error.
+ bool Init();
+
+ // Close the read pipe. This only needs to be used when the read pipe needs to
+ // be closed earlier.
+ void CloseReadFd();
+
+ // Close the write pipe. This only needs to be used when the write pipe needs
+ // to be closed earlier.
+ void CloseWriteFd();
+
+ // Reads characters until newline or end of pipe. On read failure this will
+ // close the read pipe, but continue to return true and read buffered lines
+ // until the internal buffering is exhausted. This will block if there is no
+ // data available on the read pipe.
+ bool ReadLine(std::string& line);
+
+ // Writes bytes to the write end of the pipe, returns false and closes write
+ // pipe on failure.
+ bool WriteForTesting(const void* bytes, size_t bytes_len);
+
+ // Calls the dup2 system call to replace any existing open file descriptor
+ // with number new_fd with a copy of the current write end file descriptor
+ // for the pipe.
+ int Dup2WriteFd(int new_fd) const;
+
+ private:
+ int GetReadFd() const {
+ return fds_[0];
+ }
+
+ int GetWriteFd() const {
+ return fds_[1];
+ }
+
+ int fds_[2];
+ std::string read_buffer_;
+};
+
+} // namespace google_breakpad
+
+#endif // COMMON_LINUX_SCOPED_PIPE_H_