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/* $NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $ */
/*
* Copyright (c) 1988, 1993, 2006
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software written by Ken Arnold and
* published in UNIX Review, Vol. 6, No. 8.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
*/
/*
FUNCTION
<<popen>>, <<pclose>>---tie a stream to a command string
INDEX
popen
INDEX
pclose
ANSI_SYNOPSIS
#include <stdio.h>
FILE *popen(const char *<[s]>, const char *<[mode]>);
int pclose(FILE *<[f]>);
DESCRIPTION
Use <<popen>> to create a stream to a child process executing a
command string <<*<[s]>>> as processed by <</bin/sh>> on your system.
The argument <[mode]> must start with either `<<r>>', where the stream
reads from the child's <<stdout>>, or `<<w>>', where the stream writes
to the child's <<stdin>>. As an extension, <[mode]> may also contain
`<<e>>' to set the close-on-exec bit of the parent's file descriptor.
The stream created by <<popen>> must be closed by <<pclose>> to avoid
resource leaks.
Streams created by prior calls to <<popen>> are not visible in
subsequent <<popen>> children, regardless of the close-on-exec bit.
Use ``<<system(NULL)>>'' to test whether your system has <</bin/sh>>
available.
RETURNS
<<popen>> returns a file stream opened with the specified <[mode]>,
or <<NULL>> if a child process could not be created. <<pclose>>
returns -1 if the stream was not created by <<popen>> or if the
application used <<wait>> or similar to steal the status; otherwise
it returns the exit status of the child which can be interpreted
in the same manner as a status obtained by <<waitpid>>.
PORTABILITY
POSIX.2 requires <<popen>> and <<pclose>>, but only specifies a mode
of just <<r>> or <<w>>. Where <<sh>> is found is left unspecified.
Supporting OS subroutines required: <<_exit>>, <<_execve>>, <<_fork_r>>,
<<_wait_r>>, <<pipe>>, <<fcntl>>, <<sbrk>>.
*/
#ifndef _NO_POPEN
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)popen.c 8.1 (Berkeley) 6/4/93";
#else
static char rcsid[] = "$NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $";
#endif
#endif /* LIBC_SCCS and not lint */
#include <sys/param.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <paths.h>
#include <fcntl.h>
static struct pid {
struct pid *next;
FILE *fp;
pid_t pid;
} *pidlist;
FILE *
_DEFUN(popen, (program, type),
const char *program _AND
const char *type)
{
struct pid *cur, *last;
FILE *iop;
int pdes[2], pid;
if ((*type != 'r' && *type != 'w')
|| (type[1]
#ifdef HAVE_FCNTL
&& (type[2] || (type[1] != 'e'))
#endif
)) {
errno = EINVAL;
return (NULL);
}
if ((cur = malloc(sizeof(struct pid))) == NULL)
return (NULL);
if (pipe(pdes) < 0) {
free(cur);
return (NULL);
}
switch (pid = vfork()) {
case -1: /* Error. */
(void)close(pdes[0]);
(void)close(pdes[1]);
free(cur);
return (NULL);
/* NOTREACHED */
case 0: /* Child. */
if (*type == 'r') {
if (pdes[1] != STDOUT_FILENO) {
(void)dup2(pdes[1], STDOUT_FILENO);
(void)close(pdes[1]);
}
if (pdes[0] != STDOUT_FILENO) {
(void) close(pdes[0]);
}
} else {
if (pdes[0] != STDIN_FILENO) {
(void)dup2(pdes[0], STDIN_FILENO);
(void)close(pdes[0]);
}
(void)close(pdes[1]);
}
/* Close all fd's created by prior popen. */
for (last = NULL, cur = pidlist; cur;
last = cur, cur = cur->next)
(void)close (fileno (cur->fp));
execl(_PATH_BSHELL, "sh", "-c", program, NULL);
_exit(127);
/* NOTREACHED */
}
/* Parent; assume fdopen can't fail. */
if (*type == 'r') {
iop = fdopen(pdes[0], type);
(void)close(pdes[1]);
} else {
iop = fdopen(pdes[1], type);
(void)close(pdes[0]);
}
#ifdef HAVE_FCNTL
/* Mark pipe cloexec if requested. */
if (type[1] == 'e')
fcntl (fileno (iop), F_SETFD,
fcntl (fileno (iop), F_GETFD, 0) | FD_CLOEXEC);
#endif /* HAVE_FCNTL */
/* Link into list of file descriptors. */
cur->fp = iop;
cur->pid = pid;
cur->next = pidlist;
pidlist = cur;
return (iop);
}
/*
* pclose --
* Pclose returns -1 if stream is not associated with a `popened' command,
* if already `pclosed', or waitpid returns an error.
*/
int
_DEFUN(pclose, (iop),
FILE *iop)
{
register struct pid *cur, *last;
int pstat;
pid_t pid;
(void)fclose(iop);
/* Find the appropriate file pointer. */
for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
if (cur->fp == iop)
break;
if (cur == NULL)
return (-1);
do {
pid = waitpid(cur->pid, &pstat, 0);
} while (pid == -1 && errno == EINTR);
/* Remove the entry from the linked list. */
if (last == NULL)
pidlist = cur->next;
else
last->next = cur->next;
free(cur);
return (pid == -1 ? -1 : pstat);
}
#endif /* !_NO_POPEN */
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