222 lines
5.9 KiB
C
222 lines
5.9 KiB
C
/* Copyright (C) 1991, 1992, 1993, 1996, 1997 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <errno.h>
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#include <stddef.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <fcntl.h>
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#define SH_PATH "/bin/sh" /* Shell to run. */
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#define SH_NAME "sh" /* Name to give it. */
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/* Structure describing a popen child. */
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struct child
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{
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pid_t pid; /* PID of the child. */
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__ptr_t cookie; /* Original cookie from fdopen. */
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__io_functions funcs; /* Original functions from fdopen. */
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};
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/* io_functions for pipe streams.
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These all simply call the corresponding
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original function with the original cookie. */
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#define FUNC(type, name, proto, args) \
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static type __CONCAT(child_,name) proto \
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{ \
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struct child *c = (struct child *) cookie; \
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{ \
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__ptr_t cookie = c->cookie; \
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return (*c->funcs.__CONCAT(__,name)) args; \
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} \
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}
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FUNC (int, read, (void *cookie, char *buf, size_t n), (cookie, buf, n))
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FUNC (int, write, (void *cookie, const char *buf, size_t n), (cookie, buf, n))
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FUNC (int, seek, (void *cookie, fpos_t *pos, int whence),
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(cookie, pos, whence))
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FUNC (int, close, (void *cookie), (cookie))
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FUNC (int, fileno, (void *cookie), (cookie))
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static const __io_functions child_funcs
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= { child_read, child_write, child_seek, child_close, child_fileno };
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/* Open a new stream that is a one-way pipe to a
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child process running the given shell command. */
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FILE *
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popen (command, mode)
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const char *command;
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const char *mode;
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{
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pid_t pid;
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int pipedes[2];
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FILE *stream;
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struct child *child;
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if (command == NULL || mode == NULL || (*mode != 'r' && *mode != 'w'))
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{
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__set_errno (EINVAL);
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return NULL;
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}
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/* Create the pipe. */
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if (pipe (pipedes) < 0)
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return NULL;
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/* Fork off the child. */
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pid = __vfork ();
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if (pid == (pid_t) -1)
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{
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/* The fork failed. */
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(void) close (pipedes[0]);
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(void) close (pipedes[1]);
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return NULL;
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}
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else if (pid == (pid_t) 0)
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{
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/* We are the child side. Make the write side of
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the pipe be stdin or the read side be stdout. */
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const char *new_argv[4];
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if ((*mode == 'w' ? dup2(pipedes[STDIN_FILENO], STDIN_FILENO) :
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dup2 (pipedes[STDOUT_FILENO], STDOUT_FILENO)) < 0)
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_exit (127);
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/* Close the pipe descriptors. */
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(void) close (pipedes[STDIN_FILENO]);
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(void) close (pipedes[STDOUT_FILENO]);
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/* Exec the shell. */
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new_argv[0] = SH_NAME;
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new_argv[1] = "-c";
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new_argv[2] = command;
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new_argv[3] = NULL;
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(void) execve (SH_PATH, (char *const *) new_argv, environ);
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/* Die if it failed. */
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_exit (127);
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}
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/* We are the parent side. */
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/* Close the irrelevant side of the pipe and open the relevant side as a
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new stream. Mark our side of the pipe to close on exec, so new children
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won't see it. */
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if (*mode == 'r')
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{
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(void) close (pipedes[STDOUT_FILENO]);
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(void) fcntl (pipedes[STDIN_FILENO], F_SETFD, FD_CLOEXEC);
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stream = fdopen (pipedes[STDIN_FILENO], mode);
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}
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else
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{
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(void) close (pipedes[STDIN_FILENO]);
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(void) fcntl (pipedes[STDOUT_FILENO], F_SETFD, FD_CLOEXEC);
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stream = fdopen (pipedes[STDOUT_FILENO], mode);
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}
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if (stream == NULL)
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goto error;
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child = (struct child *) malloc (sizeof (struct child));
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if (child == NULL)
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goto error;
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{
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/* Make sure STREAM has its functions set before
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we try to squirrel them away in CHILD. */
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extern void __stdio_check_funcs __P ((FILE *));
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__stdio_check_funcs (stream);
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}
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child->pid = pid;
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child->cookie = stream->__cookie;
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child->funcs = stream->__io_funcs;
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stream->__cookie = (void *) child;
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stream->__io_funcs = child_funcs;
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stream->__ispipe = 1;
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return stream;
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error:
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{
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/* The stream couldn't be opened or the child structure couldn't be
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allocated. Kill the child and close the other side of the pipe. */
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int save = errno;
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(void) kill (pid, SIGKILL);
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if (stream == NULL)
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(void) close (pipedes[*mode == 'r' ? STDOUT_FILENO : STDIN_FILENO]);
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else
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(void) fclose (stream);
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#ifndef NO_WAITPID
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(void) waitpid (pid, (int *) NULL, 0);
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#else
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{
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pid_t dead;
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do
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dead = wait ((int *) NULL);
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while (dead > 0 && dead != pid);
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}
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#endif
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__set_errno (save);
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return NULL;
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}
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}
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/* Close a stream opened by popen and return its status.
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Returns -1 if the stream was not opened by popen. */
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int
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pclose (stream)
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register FILE *stream;
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{
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struct child *c;
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pid_t pid, dead;
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int status;
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if (!__validfp (stream) || !stream->__ispipe)
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{
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__set_errno (EINVAL);
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return -1;
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}
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c = (struct child *) stream->__cookie;
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pid = c->pid;
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stream->__cookie = c->cookie;
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stream->__io_funcs = c->funcs;
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free ((void *) c);
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stream->__ispipe = 0;
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if (fclose (stream))
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return -1;
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#ifndef NO_WAITPID
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dead = waitpid (pid, &status, 0);
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#else
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do
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dead = wait (&status);
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while (dead > 0 && dead != pid);
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#endif
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if (dead != pid)
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status = -1;
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return status;
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}
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