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Initial version.
This commit is contained in:
Paul Eggert
196
lib/subpipe.c
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196
lib/subpipe.c
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/* Subprocesses with pipes.
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Copyright (C) 2002 Free Software Foundation, Inc.
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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 2, or (at your option)
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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, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/* Written by Paul Eggert <eggert@twinsun.com>
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and Florian Krohm <florian@edamail.fishkill.ibm.com>. */
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#if HAVE_SYS_TYPES_H
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# include <sys/types.h>
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#endif
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#include <errno.h>
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#ifndef errno
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extern int errno;
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#endif
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#include <signal.h>
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#if ! defined SIGCHLD && defined SIGCLD
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# define SIGCHLD SIGCLD
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#endif
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#if HAVE_STDLIB_H
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# include <stdlib.h>
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#endif
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/* The following test is to work around the gross typo in
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systems like Sony NEWS-OS Release 4.0C, whereby EXIT_FAILURE
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is defined to 0, not 1. */
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#if ! EXIT_FAILURE
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# undef EXIT_FAILURE
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# define EXIT_FAILURE 1
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#endif
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#ifndef STDIN_FILENO
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# define STDIN_FILENO 0
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#endif
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#ifndef STDOUT_FILENO
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# define STDOUT_FILENO 1
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#endif
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#if ! HAVE_DUP2 && ! defined dup2
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# if HAVE_FCNTL_H
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# include <fcntl.h>
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# endif
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# define dup2(f, t) (close (t), fcntl (f, F_DUPFD, t))
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#endif
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#if HAVE_SYS_WAIT_H
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# include <sys/wait.h>
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#endif
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#ifndef WEXITSTATUS
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# define WEXITSTATUS(stat_val) ((unsigned int) (stat_val) >> 8)
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#endif
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#ifndef WIFEXITED
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# define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
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#endif
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#if HAVE_VFORK_H
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# include <vfork.h>
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#endif
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#if ! HAVE_WORKING_VFORK
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# define vfork fork
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#endif
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#include "error.h"
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#include "gettext.h"
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#define _(Msgid) gettext (Msgid)
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#include "subpipe.h"
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/* Initialize this module. */
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void
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init_subpipe (void)
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{
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#ifdef SIGCHLD
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/* System V fork+wait does not work if SIGCHLD is ignored. */
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signal (SIGCHLD, SIG_DFL);
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#endif
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}
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/* Create a subprocess that is run as a filter. ARGV is the
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NULL-terminated argument vector for the subprocess. Store read and
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write file descriptors for communication with the subprocess into
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FD[0] and FD[1]: input meant for the process can be written into
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FD[0], and output from the process can be read from FD[1]. Return
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the subprocess id.
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To avoid deadlock, the invoker must not let incoming data pile up
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in FD[1] while writing data to FD[0]. */
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pid_t
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create_subpipe (char const * const *argv, int fd[2])
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{
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int pipe_fd[2];
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int from_in_fd;
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int from_out_fd;
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int to_in_fd;
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int to_out_fd;
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pid_t pid;
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if (pipe (pipe_fd) != 0)
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error (EXIT_FAILURE, errno, "pipe");
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to_in_fd = pipe_fd[0];
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to_out_fd = pipe_fd[1];
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if (pipe (pipe_fd) != 0)
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error (EXIT_FAILURE, errno, "pipe");
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from_in_fd = pipe_fd[0];
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from_out_fd = pipe_fd[1];
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pid = vfork ();
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if (pid < 0)
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error (EXIT_FAILURE, errno, "fork");
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if (! pid)
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{
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/* Child. */
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close (to_out_fd);
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close (from_in_fd);
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if (to_in_fd != STDIN_FILENO)
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{
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dup2 (to_in_fd, STDIN_FILENO);
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close (to_in_fd);
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}
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if (from_out_fd != STDOUT_FILENO)
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{
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dup2 (from_out_fd, STDOUT_FILENO);
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close (from_out_fd);
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}
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/* The cast to (char **) rather than (char * const *) is needed
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for portability to older hosts with a nonstandard prototype
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for execvp. */
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execvp (argv[0], (char **) argv);
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_exit (errno == ENOENT ? 127 : 126);
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}
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/* Parent. */
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close (to_in_fd);
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close (from_out_fd);
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fd[0] = to_out_fd;
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fd[1] = from_in_fd;
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return pid;
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}
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/* Wait for the subprocess to exit. */
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void
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reap_subpipe (pid_t pid, char const *program)
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{
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#if HAVE_WAITPID || defined waitpid
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int wstatus;
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if (waitpid (pid, &wstatus, 0) < 0)
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error (EXIT_FAILURE, errno, "waitpid");
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else
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{
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int status = WIFEXITED (wstatus) ? WEXITSTATUS (wstatus) : -1;
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if (status)
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error (EXIT_FAILURE, 0,
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_(status == 126
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? "subsidiary program `%s' could not be invoked"
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: status == 127
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? "subsidiary program `%s' not found"
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: status < 0
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? "subsidiary program `%s' failed"
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: "subsidiary program `%s' failed (exit status %d)"),
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program, status);
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}
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#endif
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}
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