232 lines
6.2 KiB
C
232 lines
6.2 KiB
C
/* $NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $ */
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/*
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* Copyright (c) 1988, 1993, 2006
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software written by Ken Arnold and
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* published in UNIX Review, Vol. 6, No. 8.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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FUNCTION
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<<popen>>, <<pclose>>---tie a stream to a command string
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INDEX
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popen
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INDEX
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pclose
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ANSI_SYNOPSIS
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#include <stdio.h>
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FILE *popen(char *<[s]>, char *<[mode]>);
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int pclose(FILE *<[f]>);
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DESCRIPTION
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Use <<popen>> to create a stream to a child process executing a
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command string <<*<[s]>>> as processed by <</bin/sh>> on your system.
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The argument <[mode]> must start with either `<<r>>', where the stream
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reads from the child's <<stdout>>, or `<<w>>', where the stream writes
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to the child's <<stdin>>. As an extension, <[mode]> may also contain
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`<<e>>' to set the close-on-exec bit of the parent's file descriptor.
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The stream created by <<popen>> must be closed by <<pclose>> to avoid
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resource leaks.
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Streams created by prior calls to <<popen>> are not visible in
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subsequent <<popen>> children, regardless of the close-on-exec bit.
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Use ``<<system(NULL)>>'' to test whether your system has <</bin/sh>>
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available.
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RETURNS
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<<popen>> returns a file stream opened with the specified <[mode]>,
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or <<NULL>> if a child process could not be created. <<pclose>>
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returns -1 if the stream was not created by <<popen>> or if the
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application used <<wait>> or similar to steal the status; otherwise
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it returns the exit status of the child which can be interpreted
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in the same manner as a status obtained by <<waitpid>>.
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PORTABILITY
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POSIX.2 requires <<popen>> and <<pclose>>, but only specifies a mode
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of just <<r>> or <<w>>. Where <<sh>> is found is left unspecified.
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Supporting OS subroutines required: <<_exit>>, <<_execve>>, <<_fork_r>>,
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<<_wait_r>>, <<pipe>>, <<fcntl>>, <<sbrk>>.
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*/
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#ifndef _NO_POPEN
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)popen.c 8.1 (Berkeley) 6/4/93";
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#else
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static char rcsid[] = "$NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $";
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#endif
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#endif /* LIBC_SCCS and not lint */
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#include <sys/param.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <signal.h>
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#include <errno.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <paths.h>
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#include <fcntl.h>
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static struct pid {
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struct pid *next;
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FILE *fp;
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pid_t pid;
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} *pidlist;
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FILE *
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_DEFUN(popen, (program, type),
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const char *program _AND
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const char *type)
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{
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struct pid *cur, *last;
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FILE *iop;
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int pdes[2], pid;
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if ((*type != 'r' && *type != 'w')
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|| (type[1]
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#ifdef HAVE_FCNTL
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&& (type[2] || (type[1] != 'e'))
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#endif
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)) {
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errno = EINVAL;
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return (NULL);
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}
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if ((cur = malloc(sizeof(struct pid))) == NULL)
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return (NULL);
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if (pipe(pdes) < 0) {
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free(cur);
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return (NULL);
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}
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switch (pid = vfork()) {
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case -1: /* Error. */
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(void)close(pdes[0]);
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(void)close(pdes[1]);
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free(cur);
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return (NULL);
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/* NOTREACHED */
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case 0: /* Child. */
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if (*type == 'r') {
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if (pdes[1] != STDOUT_FILENO) {
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(void)dup2(pdes[1], STDOUT_FILENO);
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(void)close(pdes[1]);
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}
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if (pdes[0] != STDOUT_FILENO) {
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(void) close(pdes[0]);
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}
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} else {
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if (pdes[0] != STDIN_FILENO) {
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(void)dup2(pdes[0], STDIN_FILENO);
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(void)close(pdes[0]);
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}
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(void)close(pdes[1]);
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}
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/* Close all fd's created by prior popen. */
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for (last = NULL, cur = pidlist; cur;
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last = cur, cur = cur->next)
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(void)close (fileno (cur->fp));
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execl(_PATH_BSHELL, "sh", "-c", program, NULL);
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_exit(127);
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/* NOTREACHED */
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}
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/* Parent; assume fdopen can't fail. */
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if (*type == 'r') {
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iop = fdopen(pdes[0], type);
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(void)close(pdes[1]);
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} else {
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iop = fdopen(pdes[1], type);
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(void)close(pdes[0]);
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}
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#ifdef HAVE_FCNTL
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/* Mark pipe cloexec if requested. */
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if (type[1] == 'e')
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fcntl (fileno (iop), F_SETFD,
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fcntl (fileno (iop), F_GETFD, 0) | FD_CLOEXEC);
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#endif /* HAVE_FCNTL */
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/* Link into list of file descriptors. */
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cur->fp = iop;
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cur->pid = pid;
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cur->next = pidlist;
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pidlist = cur;
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return (iop);
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}
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/*
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* pclose --
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* Pclose returns -1 if stream is not associated with a `popened' command,
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* if already `pclosed', or waitpid returns an error.
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*/
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int
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_DEFUN(pclose, (iop),
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FILE *iop)
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{
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register struct pid *cur, *last;
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int pstat;
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pid_t pid;
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(void)fclose(iop);
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/* Find the appropriate file pointer. */
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for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
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if (cur->fp == iop)
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break;
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if (cur == NULL)
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return (-1);
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do {
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pid = waitpid(cur->pid, &pstat, 0);
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} while (pid == -1 && errno == EINTR);
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/* Remove the entry from the linked list. */
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if (last == NULL)
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pidlist = cur->next;
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else
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last->next = cur->next;
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free(cur);
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return (pid == -1 ? -1 : pstat);
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}
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#endif /* !_NO_POPEN */
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