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/* Creation of subprocesses, communicating via pipes.
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Copyright (C) 2001-2004, 2006-2011 Free Software Foundation, Inc.
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Written by Bruno Haible <haible@clisp.cons.org>, 2001.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "spawn-pipe.h"
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#include "fatal-signal.h"
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#include "unistd-safer.h"
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#include "wait-process.h"
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#define _(str) gettext (str)
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#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
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/* Native Woe32 API. */
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# include "w32spawn.h"
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/* The results of open() in this file are not used with fchdir,
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therefore save some unnecessary work in fchdir.c. */
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/* EINTR handling for close().
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These functions can return -1/EINTR even though we don't have any
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signal handlers set up, namely when we get interrupted via SIGSTOP. */
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nonintr_close (int fd)
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while (retval < 0 && errno == EINTR);
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#define close nonintr_close
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nonintr_open (const char *pathname, int oflag, mode_t mode)
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retval = open (pathname, oflag, mode);
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while (retval < 0 && errno == EINTR);
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#undef open /* avoid warning on VMS */
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#define open nonintr_open
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/* Open a pipe connected to a child process.
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* parent -> fd[1] -> STDIN_FILENO -> child if pipe_stdin
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* parent <- fd[0] <- STDOUT_FILENO <- child if pipe_stdout
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* At least one of pipe_stdin, pipe_stdout must be true.
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* pipe_stdin and prog_stdin together determine the child's standard input.
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* pipe_stdout and prog_stdout together determine the child's standard output.
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* If pipe_stdin is true, prog_stdin is ignored.
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* If pipe_stdout is true, prog_stdout is ignored.
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create_pipe (const char *progname,
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const char *prog_path, char **prog_argv,
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bool pipe_stdin, bool pipe_stdout,
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const char *prog_stdin, const char *prog_stdout,
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bool slave_process, bool exit_on_error,
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#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
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This uses _pipe(), dup2(), and spawnv(). It could also be implemented
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using the low-level functions CreatePipe(), DuplicateHandle(),
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CreateProcess() and _open_osfhandle(); see the GNU make and GNU clisp
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and cvs source code. */
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/* FIXME: Need to free memory allocated by prepare_spawn. */
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prog_argv = prepare_spawn (prog_argv);
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if (pipe2_safer (ifd, O_BINARY | O_CLOEXEC) < 0)
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error (EXIT_FAILURE, errno, _("cannot create pipe"));
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if (pipe2_safer (ofd, O_BINARY | O_CLOEXEC) < 0)
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error (EXIT_FAILURE, errno, _("cannot create pipe"));
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/* Data flow diagram:
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* parent -> ofd[1] -> ofd[0] -> child if pipe_stdin
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* parent <- ifd[0] <- ifd[1] <- child if pipe_stdout
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/* Save standard file handles of parent process. */
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if (pipe_stdin || prog_stdin != NULL)
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orig_stdin = dup_safer_noinherit (STDIN_FILENO);
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if (pipe_stdout || prog_stdout != NULL)
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orig_stdout = dup_safer_noinherit (STDOUT_FILENO);
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orig_stderr = dup_safer_noinherit (STDERR_FILENO);
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/* Create standard file handles of child process. */
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if ((!pipe_stdin || dup2 (ofd[0], STDIN_FILENO) >= 0)
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&& (!pipe_stdout || dup2 (ifd[1], STDOUT_FILENO) >= 0)
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|| ((nulloutfd = open ("NUL", O_RDWR, 0)) >= 0
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&& (nulloutfd == STDERR_FILENO
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|| (dup2 (nulloutfd, STDERR_FILENO) >= 0
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&& close (nulloutfd) >= 0))))
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|| prog_stdin == NULL
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|| ((stdinfd = open (prog_stdin, O_RDONLY, 0)) >= 0
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&& (stdinfd == STDIN_FILENO
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|| (dup2 (stdinfd, STDIN_FILENO) >= 0
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&& close (stdinfd) >= 0))))
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|| prog_stdout == NULL
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|| ((stdoutfd = open (prog_stdout, O_WRONLY, 0)) >= 0
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&& (stdoutfd == STDOUT_FILENO
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|| (dup2 (stdoutfd, STDOUT_FILENO) >= 0
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&& close (stdoutfd) >= 0)))))
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/* The child process doesn't inherit ifd[0], ifd[1], ofd[0], ofd[1],
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but it inherits all open()ed or dup2()ed file handles (which is what
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we want in the case of STD*_FILENO). */
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/* Use spawnvpe and pass the environment explicitly. This is needed if
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the program has modified the environment using putenv() or [un]setenv().
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On Windows, programs have two environments, one in the "environment
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block" of the process and managed through SetEnvironmentVariable(), and
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one inside the process, in the location retrieved by the 'environ'
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macro. When using spawnvp() without 'e', the child process inherits a
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copy of the environment block - ignoring the effects of putenv() and
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child = spawnvpe (P_NOWAIT, prog_path, (const char **) prog_argv,
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(const char **) environ);
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if (child < 0 && errno == ENOEXEC)
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/* prog is not a native executable. Try to execute it as a
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shell script. Note that prepare_spawn() has already prepended
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a hidden element "sh.exe" to prog_argv. */
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child = spawnvpe (P_NOWAIT, prog_argv[0], (const char **) prog_argv,
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(const char **) environ);
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/* Restore standard file handles of parent process. */
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undup_safer_noinherit (orig_stderr, STDERR_FILENO);
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if (pipe_stdout || prog_stdout != NULL)
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undup_safer_noinherit (orig_stdout, STDOUT_FILENO);
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if (pipe_stdin || prog_stdin != NULL)
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undup_safer_noinherit (orig_stdin, STDIN_FILENO);
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if (exit_on_error || !null_stderr)
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error (exit_on_error ? EXIT_FAILURE : 0, saved_errno,
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_("%s subprocess failed"), progname);
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sigset_t blocked_signals;
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posix_spawn_file_actions_t actions;
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bool actions_allocated;
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posix_spawnattr_t attrs;
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bool attrs_allocated;
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if (pipe_safer (ifd) < 0)
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error (EXIT_FAILURE, errno, _("cannot create pipe"));
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if (pipe_safer (ofd) < 0)
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error (EXIT_FAILURE, errno, _("cannot create pipe"));
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/* Data flow diagram:
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* parent -> ofd[1] -> ofd[0] -> child if pipe_stdin
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* parent <- ifd[0] <- ifd[1] <- child if pipe_stdout
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sigprocmask (SIG_SETMASK, NULL, &blocked_signals);
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block_fatal_signals ();
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actions_allocated = false;
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attrs_allocated = false;
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if ((err = posix_spawn_file_actions_init (&actions)) != 0
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|| (actions_allocated = true,
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&& (err = posix_spawn_file_actions_adddup2 (&actions,
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ofd[0], STDIN_FILENO))
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&& (err = posix_spawn_file_actions_adddup2 (&actions,
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ifd[1], STDOUT_FILENO))
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&& (err = posix_spawn_file_actions_addclose (&actions, ofd[0]))
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&& (err = posix_spawn_file_actions_addclose (&actions, ifd[1]))
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&& (err = posix_spawn_file_actions_addclose (&actions, ofd[1]))
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&& (err = posix_spawn_file_actions_addclose (&actions, ifd[0]))
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&& (err = posix_spawn_file_actions_addopen (&actions,
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&& prog_stdin != NULL
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&& (err = posix_spawn_file_actions_addopen (&actions,
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prog_stdin, O_RDONLY,
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&& prog_stdout != NULL
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&& (err = posix_spawn_file_actions_addopen (&actions,
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prog_stdout, O_WRONLY,
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&& ((err = posix_spawnattr_init (&attrs)) != 0
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|| (attrs_allocated = true,
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(err = posix_spawnattr_setsigmask (&attrs,
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|| (err = posix_spawnattr_setflags (&attrs,
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POSIX_SPAWN_SETSIGMASK))
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|| (err = posix_spawnp (&child, prog_path, &actions,
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attrs_allocated ? &attrs : NULL, prog_argv,
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if (actions_allocated)
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posix_spawn_file_actions_destroy (&actions);
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posix_spawnattr_destroy (&attrs);
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unblock_fatal_signals ();
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if (exit_on_error || !null_stderr)
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error (exit_on_error ? EXIT_FAILURE : 0, err,
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_("%s subprocess failed"), progname);
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posix_spawn_file_actions_destroy (&actions);
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posix_spawnattr_destroy (&attrs);
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register_slave_subprocess (child);
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unblock_fatal_signals ();
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/* Open a bidirectional pipe.
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* parent -> fd[1] -> STDIN_FILENO -> child
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* parent <- fd[0] <- STDOUT_FILENO <- child
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create_pipe_bidi (const char *progname,
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const char *prog_path, char **prog_argv,
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bool slave_process, bool exit_on_error,
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pid_t result = create_pipe (progname, prog_path, prog_argv,
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true, true, NULL, NULL,
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null_stderr, slave_process, exit_on_error,
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/* Open a pipe for input from a child process.
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* The child's stdin comes from a file.
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* parent <- fd[0] <- STDOUT_FILENO <- child
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create_pipe_in (const char *progname,
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const char *prog_path, char **prog_argv,
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const char *prog_stdin, bool null_stderr,
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bool slave_process, bool exit_on_error,
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pid_t result = create_pipe (progname, prog_path, prog_argv,
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false, true, prog_stdin, NULL,
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null_stderr, slave_process, exit_on_error,
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/* Open a pipe for output to a child process.
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* The child's stdout goes to a file.
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* parent -> fd[0] -> STDIN_FILENO -> child
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create_pipe_out (const char *progname,
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const char *prog_path, char **prog_argv,
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const char *prog_stdout, bool null_stderr,
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bool slave_process, bool exit_on_error,
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pid_t result = create_pipe (progname, prog_path, prog_argv,
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true, false, NULL, prog_stdout,
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null_stderr, slave_process, exit_on_error,