// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// http://code.google.com/p/protobuf/
//
// 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 Inc. 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.
// Author: kenton@google.com (Kenton Varda)
#include <google/protobuf/compiler/subprocess.h>
#include <algorithm>
#include <errno.h>
#include <sys/wait.h>
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/message.h>
#include <google/protobuf/stubs/substitute.h>
namespace google {
namespace protobuf {
namespace compiler {
Subprocess::Subprocess()
: child_pid_(-1), child_stdin_(-1), child_stdout_(-1) {}
Subprocess::~Subprocess() {
if (child_stdin_ != -1) {
close(child_stdin_);
}
if (child_stdout_ != -1) {
close(child_stdout_);
}
}
void Subprocess::Start(const string& program, SearchMode search_mode) {
// Note that we assume that there are no other threads, thus we don't have to
// do crazy stuff like using socket pairs or avoiding libc locks.
// [0] is read end, [1] is write end.
int stdin_pipe[2];
int stdout_pipe[2];
pipe(stdin_pipe);
pipe(stdout_pipe);
char* argv[2] = { strdup(program.c_str()), NULL };
child_pid_ = fork();
if (child_pid_ == -1) {
GOOGLE_LOG(FATAL) << "fork: " << strerror(errno);
} else if (child_pid_ == 0) {
// We are the child.
dup2(stdin_pipe[0], STDIN_FILENO);
dup2(stdout_pipe[1], STDOUT_FILENO);
close(stdin_pipe[0]);
close(stdin_pipe[1]);
close(stdout_pipe[0]);
close(stdout_pipe[1]);
switch (search_mode) {
case SEARCH_PATH:
execvp(argv[0], argv);
break;
case EXACT_NAME:
execv(argv[0], argv);
break;
}
// Write directly to STDERR_FILENO to avoid stdio code paths that may do
// stuff that is unsafe here.
write(STDERR_FILENO, argv[0], strlen(argv[0]));
const char* message = ": program not found or is not executable\n";
write(STDERR_FILENO, message, strlen(message));
// Must use _exit() rather than exit() to avoid flushing output buffers
// that will also be flushed by the parent.
_exit(1);
} else {
free(argv[0]);
close(stdin_pipe[0]);
close(stdout_pipe[1]);
child_stdin_ = stdin_pipe[1];
child_stdout_ = stdout_pipe[0];
}
}
bool Subprocess::Communicate(const Message& input, Message* output,
string* error) {
GOOGLE_CHECK_NE(child_stdin_, -1) << "Must call Start() first.";
// The "sighandler_t" typedef is GNU-specific, so define our own.
typedef void SignalHandler(int);
// Make sure SIGPIPE is disabled so that if the child dies it doesn't kill us.
SignalHandler* old_pipe_handler = signal(SIGPIPE, SIG_IGN);
string input_data = input.SerializeAsString();
string output_data;
int input_pos = 0;
int max_fd = max(child_stdin_, child_stdout_);
while (child_stdout_ != -1) {
fd_set read_fds;
fd_set write_fds;
FD_ZERO(&read_fds);
FD_ZERO(&write_fds);
if (child_stdout_ != -1) {
FD_SET(child_stdout_, &read_fds);
}
if (child_stdin_ != -1) {
FD_SET(child_stdin_, &write_fds);
}
if (select(max_fd + 1, &read_fds, &write_fds, NULL, NULL) < 0) {
if (errno == EINTR) {
// Interrupted by signal. Try again.
continue;
} else {
GOOGLE_LOG(FATAL) << "select: " << strerror(errno);
}
}
if (child_stdin_ != -1 && FD_ISSET(child_stdin_, &write_fds)) {
int n = write(child_stdin_, input_data.data() + input_pos,
input_data.size() - input_pos);
if (n < 0) {
// Child closed pipe. Presumably it will report an error later.
// Pretend we're done for now.
input_pos = input_data.size();
} else {
input_pos += n;
}
if (input_pos == input_data.size()) {
// We're done writing. Close.
close(child_stdin_);
child_stdin_ = -1;
}
}
if (child_stdout_ != -1 && FD_ISSET(child_stdout_, &read_fds)) {
char buffer[4096];
int n = read(child_stdout_, buffer, sizeof(buffer));
if (n > 0) {
output_data.append(buffer, n);
} else {
// We're done reading. Close.
close(child_stdout_);
child_stdout_ = -1;
}
}
}
if (child_stdin_ != -1) {
// Child did not finish reading input before it closed the output.
// Presumably it exited with an error.
close(child_stdin_);
child_stdin_ = -1;
}
int status;
while (waitpid(child_pid_, &status, 0) == -1) {
if (errno != EINTR) {
GOOGLE_LOG(FATAL) << "waitpid: " << strerror(errno);
}
}
// Restore SIGPIPE handling.
signal(SIGPIPE, old_pipe_handler);
if (WIFEXITED(status)) {
if (WEXITSTATUS(status) != 0) {
int error_code = WEXITSTATUS(status);
*error = strings::Substitute(
"Plugin failed with status code $0.", error_code);
return false;
}
} else if (WIFSIGNALED(status)) {
int signal = WTERMSIG(status);
*error = strings::Substitute(
"Plugin killed by signal $0.", signal);
return false;
} else {
*error = "Neither WEXITSTATUS nor WTERMSIG is true?";
return false;
}
if (!output->ParseFromString(output_data)) {
*error = "Plugin output is unparseable.";
return false;
}
return true;
}
} // namespace compiler
} // namespace protobuf
} // namespace google
