forked from OctaForge/libostd
make sure process exec never leaks file descriptors
This commit is contained in:
parent
6079676ac9
commit
4022897195
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@ -175,6 +175,9 @@ private:
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std::string const &cmd, std::vector<std::string> const &args,
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bool use_path
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);
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void reset();
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int pid = -1, errno_fd = -1;
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};
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183
src/process.cc
183
src/process.cc
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@ -127,9 +127,59 @@ OSTD_EXPORT void split_args_impl(
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} /* namespace detail */
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static void stdstream_close(FILE *f) {
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std::fclose(f);
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}
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#ifndef OSTD_PLATFORM_WIN32
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struct pipe {
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int fd[2] = { -1, -1 };
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~pipe() {
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if (fd[0] >= 0) {
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::close(fd[0]);
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}
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if (fd[1] >= 0) {
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::close(fd[1]);
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}
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}
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void open(process_stream use) {
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if (use != process_stream::PIPE) {
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return;
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}
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if (::pipe(fd) < 0) {
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throw process_error{errno, std::generic_category()};
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}
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}
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int &operator[](std::size_t idx) {
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return fd[idx];
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}
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void fdopen(file_stream &s, bool write) {
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FILE *p = ::fdopen(fd[std::size_t(write)], write ? "w" : "r");
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if (!p) {
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throw process_error{errno, std::generic_category()};
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}
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s.open(p, [](FILE *f) {
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std::fclose(f);
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});
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}
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void close(bool write) {
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::close(std::exchange(fd[std::size_t(write)], -1));
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}
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bool dup2(int target, pipe &err, bool write) {
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if (::dup2(fd[std::size_t(write)], target) < 0) {
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err.write_errno();
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return false;
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}
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close(write);
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return true;
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}
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void write_errno() {
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write(fd[1], int(errno), sizeof(int));
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}
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};
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OSTD_EXPORT void process_info::open_impl(
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std::string const &cmd, std::vector<std::string> const &args,
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@ -139,128 +189,104 @@ OSTD_EXPORT void process_info::open_impl(
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throw process_error{EINVAL, std::generic_category()};
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}
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#ifndef OSTD_PLATFORM_WIN32
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auto argp = std::make_unique<char *[]>(args.size() + 1);
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for (std::size_t i = 0; i < args.size(); ++i) {
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argp[i] = const_cast<char *>(args[i].data());
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}
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argp[args.size()] = nullptr;
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int fd_errno[2]; /* used to detect if exec failed */
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int fd_stdin[2];
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int fd_stdout[2];
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int fd_stderr[2];
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/* fd_errno used to detect if exec failed */
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pipe fd_errno, fd_stdin, fd_stdout, fd_stderr;
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if (
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(pipe(fd_errno) < 0) ||
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((use_in == process_stream::PIPE) && (pipe(fd_stdin) < 0)) ||
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((use_out == process_stream::PIPE) && (pipe(fd_stdout) < 0)) ||
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((use_err == process_stream::PIPE) && (pipe(fd_stderr) < 0))
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) {
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throw process_error{errno, std::generic_category()};
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}
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fd_errno.open(process_stream::PIPE);
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fd_stdin.open(use_in);
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fd_stdout.open(use_out);
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fd_stderr.open(use_err);
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auto cpid = fork();
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if (cpid == -1) {
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throw process_error{errno, std::generic_category()};
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} else if (!cpid) {
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/* child process */
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::close(fd_errno[0]);
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fd_errno.close(false);
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/* fcntl fails, write the errno to be read from parent */
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if (fcntl(fd_errno[1], F_SETFD, FD_CLOEXEC) < 0) {
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write(fd_errno[1], int(errno), sizeof(int));
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fd_errno.write_errno();
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std::exit(1);
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}
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/* prepare standard streams */
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if (use_in == process_stream::PIPE) {
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/* close writing end */
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::close(fd_stdin[1]);
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if (dup2(fd_stdin[0], STDIN_FILENO) < 0) {
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write(fd_errno[1], int(errno), sizeof(int));
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fd_stdin.close(true);
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if (!fd_stdin.dup2(STDIN_FILENO, fd_errno, false)) {
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std::exit(1);
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}
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}
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if (use_out == process_stream::PIPE) {
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/* close reading end */
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::close(fd_stdout[0]);
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if (dup2(fd_stdout[1], STDOUT_FILENO) < 0) {
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write(fd_errno[1], int(errno), sizeof(int));
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fd_stdout.close(false);
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if (!fd_stdout.dup2(STDOUT_FILENO, fd_errno, true)) {
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std::exit(1);
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}
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}
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if (use_err == process_stream::PIPE) {
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/* close reading end */
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::close(fd_stderr[0]);
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if (dup2(fd_stderr[1], STDERR_FILENO) < 0) {
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write(fd_errno[1], int(errno), sizeof(int));
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fd_stderr.close(false);
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if (!fd_stderr.dup2(STDERR_FILENO, fd_errno, true)) {
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std::exit(1);
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}
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} else if (use_err == process_stream::STDOUT) {
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if (dup2(STDOUT_FILENO, STDERR_FILENO) < 0) {
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write(fd_errno[1], int(errno), sizeof(int));
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fd_errno.write_errno();
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std::exit(1);
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}
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}
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int ret = 0;
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if (use_path) {
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ret = execvp(cmd.data(), argp.get());
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execvp(cmd.data(), argp.get());
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} else {
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ret = execv(cmd.data(), argp.get());
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execv(cmd.data(), argp.get());
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}
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/* exec has returned, so error has occured */
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fd_errno.write_errno();
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std::exit(1);
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} else {
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/* parent process */
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::close(fd_errno[1]);
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fd_errno.close(true);
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if (use_in == process_stream::PIPE) {
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/* close reading end */
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::close(fd_stdin[0]);
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auto p = fdopen(fd_stdin[1], "w");
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if (!p) {
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throw process_error{errno, std::generic_category()};
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}
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in.open(p, stdstream_close);
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fd_stdin.close(false);
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fd_stdin.fdopen(in, true);
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}
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if (use_out == process_stream::PIPE) {
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/* close writing end */
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::close(fd_stdout[1]);
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auto p = fdopen(fd_stdout[0], "r");
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if (!p) {
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throw process_error{errno, std::generic_category()};
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}
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out.open(p, stdstream_close);
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fd_stdout.close(true);
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fd_stdout.fdopen(out, false);
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}
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if (use_err == process_stream::PIPE) {
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/* close writing end */
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::close(fd_stderr[1]);
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auto p = fdopen(fd_stderr[0], "r");
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if (!p) {
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throw process_error{errno, std::generic_category()};
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}
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err.open(p, stdstream_close);
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fd_stderr.close(true);
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fd_stderr.fdopen(out, false);
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}
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pid = int(cpid);
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errno_fd = fd_errno[1];
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errno_fd = std::exchange(fd_errno[1], -1);
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}
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}
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OSTD_EXPORT void process_info::reset() {
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pid = -1;
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if (errno_fd >= 0) {
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::close(std::exchange(errno_fd, -1));
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}
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#else
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/* stub for now */
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return;
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#endif
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}
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OSTD_EXPORT int process_info::close() {
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if (pid < 0) {
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reset();
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throw process_error{ECHILD, std::generic_category()};
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}
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#ifndef OSTD_PLATFORM_WIN32
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int retc = 0;
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if (pid_t wp; (wp = waitpid(pid, &retc, 0)) < 0) {
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reset();
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throw process_error{errno, std::generic_category()};
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}
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if (retc) {
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int eno;
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auto r = read(errno_fd, &eno, sizeof(int));
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::close(errno_fd);
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errno_fd = -1;
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reset();
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if (r < 0) {
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throw process_error{errno, std::generic_category()};
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} else if (r == sizeof(int)) {
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@ -268,22 +294,31 @@ OSTD_EXPORT int process_info::close() {
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}
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}
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return retc;
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#else
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throw process_error{ECHILD, std::generic_category()};
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#endif
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}
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OSTD_EXPORT process_info::~process_info() {
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try {
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close();
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} catch (process_error const &) {}
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#ifndef OSTD_PLATFORM_WIN32
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if (errno_fd > 0) {
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::close(errno_fd);
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}
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#else
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return;
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#endif
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reset();
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}
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#else /* OSTD_PLATFORM_WIN32 */
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OSTD_EXPORT void process_info::open_impl(
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std::string const &, std::vector<std::string> const &, bool
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) {
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return;
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}
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OSTD_EXPORT int process_info::close() {
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throw process_error{ECHILD, std::generic_category()};
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}
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OSTD_EXPORT process_info::~process_info() {
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return;
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}
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#endif
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} /* namespace ostd */
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