Home | History | Annotate | Line # | Download | only in gen
popen.c revision 1.10 
      1 /*	$NetBSD: popen.c,v 1.10 1995/02/25 08:51:31 cgd Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1988, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software written by Ken Arnold and
      8  * published in UNIX Review, Vol. 6, No. 8.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #if defined(LIBC_SCCS) && !defined(lint)
     40 #if 0
     41 static char sccsid[] = "@(#)popen.c	8.1 (Berkeley) 6/4/93";
     42 #else
     43 static char rcsid[] = "$NetBSD: popen.c,v 1.10 1995/02/25 08:51:31 cgd Exp $";
     44 #endif
     45 #endif /* LIBC_SCCS and not lint */
     46 
     47 #include <sys/param.h>
     48 #include <sys/wait.h>
     49 
     50 #include <signal.h>
     51 #include <errno.h>
     52 #include <unistd.h>
     53 #include <stdio.h>
     54 #include <stdlib.h>
     55 #include <string.h>
     56 #include <paths.h>
     57 
     58 static struct pid {
     59 	struct pid *next;
     60 	FILE *fp;
     61 	pid_t pid;
     62 } *pidlist;
     63 
     64 FILE *
     65 popen(program, type)
     66 	const char *program;
     67 	const char *type;
     68 {
     69 	struct pid *cur;
     70 	FILE *iop;
     71 	int pdes[2], pid;
     72 
     73 	if (*type != 'r' && *type != 'w' || type[1]) {
     74 		errno = EINVAL;
     75 		return (NULL);
     76 	}
     77 
     78 	if ((cur = malloc(sizeof(struct pid))) == NULL)
     79 		return (NULL);
     80 
     81 	if (pipe(pdes) < 0) {
     82 		(void)free(cur);
     83 		return (NULL);
     84 	}
     85 
     86 	switch (pid = vfork()) {
     87 	case -1:			/* Error. */
     88 		(void)close(pdes[0]);
     89 		(void)close(pdes[1]);
     90 		(void)free(cur);
     91 		return (NULL);
     92 		/* NOTREACHED */
     93 	case 0:				/* Child. */
     94 		if (*type == 'r') {
     95 			if (pdes[1] != STDOUT_FILENO) {
     96 				(void)dup2(pdes[1], STDOUT_FILENO);
     97 				(void)close(pdes[1]);
     98 			}
     99 			(void) close(pdes[0]);
    100 		} else {
    101 			if (pdes[0] != STDIN_FILENO) {
    102 				(void)dup2(pdes[0], STDIN_FILENO);
    103 				(void)close(pdes[0]);
    104 			}
    105 			(void)close(pdes[1]);
    106 		}
    107 		execl(_PATH_BSHELL, "sh", "-c", program, NULL);
    108 		_exit(127);
    109 		/* NOTREACHED */
    110 	}
    111 
    112 	/* Parent; assume fdopen can't fail. */
    113 	if (*type == 'r') {
    114 		iop = fdopen(pdes[0], type);
    115 		(void)close(pdes[1]);
    116 	} else {
    117 		iop = fdopen(pdes[1], type);
    118 		(void)close(pdes[0]);
    119 	}
    120 
    121 	/* Link into list of file descriptors. */
    122 	cur->fp = iop;
    123 	cur->pid =  pid;
    124 	cur->next = pidlist;
    125 	pidlist = cur;
    126 
    127 	return (iop);
    128 }
    129 
    130 /*
    131  * pclose --
    132  *	Pclose returns -1 if stream is not associated with a `popened' command,
    133  *	if already `pclosed', or waitpid returns an error.
    134  */
    135 int
    136 pclose(iop)
    137 	FILE *iop;
    138 {
    139 	register struct pid *cur, *last;
    140 	int pstat;
    141 	pid_t pid;
    142 
    143 	(void)fclose(iop);
    144 
    145 	/* Find the appropriate file pointer. */
    146 	for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
    147 		if (cur->fp == iop)
    148 			break;
    149 	if (cur == NULL)
    150 		return (-1);
    151 
    152 	do {
    153 		pid = waitpid(cur->pid, &pstat, 0);
    154 	} while (pid == -1 && errno == EINTR);
    155 
    156 	/* Remove the entry from the linked list. */
    157 	if (last == NULL)
    158 		pidlist = cur->next;
    159 	else
    160 		last->next = cur->next;
    161 	free(cur);
    162 
    163 	return (pid == -1 ? -1 : pstat);
    164 }
    165