popen.c revision 23668 
1/*
2 * Copyright (c) 1988, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software written by Ken Arnold and
6 * published in UNIX Review, Vol. 6, No. 8.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#if defined(LIBC_SCCS) && !defined(lint)
38static char sccsid[] = "@(#)popen.c	8.3 (Berkeley) 5/3/95";
39#endif /* LIBC_SCCS and not lint */
40
41#include <sys/param.h>
42#include <sys/wait.h>
43#include <sys/socket.h>
44
45#include <signal.h>
46#include <errno.h>
47#include <unistd.h>
48#include <stdio.h>
49#include <stdlib.h>
50#include <string.h>
51#include <paths.h>
52
53static struct pid {
54	struct pid *next;
55	FILE *fp;
56	pid_t pid;
57} *pidlist;
58
59FILE *
60popen(command, type)
61	const char *command, *type;
62{
63	struct pid *cur;
64	FILE *iop;
65	int pdes[2], pid, twoway;
66
67	/*
68	 * Lite2 introduced two-way popen() pipes using socketpair().
69	 * FreeBSD's pipe() is bidirectional, so we use that.
70	 */
71	if (strchr(type, '+')) {
72		twoway = 1;
73		type = "r+";
74	} else  {
75		twoway = 0;
76		if (*type != 'r' && *type != 'w' || type[1])
77			return (NULL);
78	}
79	if (pipe(pdes) < 0)
80		return (NULL);
81
82	if ((cur = malloc(sizeof(struct pid))) == NULL)
83		return (NULL);
84
85	switch (pid = vfork()) {
86	case -1:			/* Error. */
87		(void)close(pdes[0]);
88		(void)close(pdes[1]);
89		free(cur);
90		return (NULL);
91		/* NOTREACHED */
92	case 0:				/* Child. */
93		if (*type == 'r') {
94			if (pdes[1] != STDOUT_FILENO) {
95				(void)dup2(pdes[1], STDOUT_FILENO);
96				(void)close(pdes[1]);
97				pdes[1] = STDOUT_FILENO;
98			}
99			(void) close(pdes[0]);
100			if (twoway && (pdes[1] != STDIN_FILENO))
101				(void)dup2(pdes[1], STDIN_FILENO);
102		} else {
103			if (pdes[0] != STDIN_FILENO) {
104				(void)dup2(pdes[0], STDIN_FILENO);
105				(void)close(pdes[0]);
106			}
107			(void)close(pdes[1]);
108		}
109		execl(_PATH_BSHELL, "sh", "-c", command, NULL);
110		_exit(127);
111		/* NOTREACHED */
112	}
113
114	/* Parent; assume fdopen can't fail. */
115	if (*type == 'r') {
116		iop = fdopen(pdes[0], type);
117		(void)close(pdes[1]);
118	} else {
119		iop = fdopen(pdes[1], type);
120		(void)close(pdes[0]);
121	}
122
123	/* Link into list of file descriptors. */
124	cur->fp = iop;
125	cur->pid =  pid;
126	cur->next = pidlist;
127	pidlist = cur;
128
129	return (iop);
130}
131
132/*
133 * pclose --
134 *	Pclose returns -1 if stream is not associated with a `popened' command,
135 *	if already `pclosed', or waitpid returns an error.
136 */
137int
138pclose(iop)
139	FILE *iop;
140{
141	register struct pid *cur, *last;
142	int omask;
143	int pstat;
144	pid_t pid;
145
146	/* Find the appropriate file pointer. */
147	for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
148		if (cur->fp == iop)
149			break;
150	if (cur == NULL)
151		return (-1);
152
153	(void)fclose(iop);
154
155	do {
156		pid = waitpid(cur->pid, &pstat, 0);
157	} while (pid == -1 && errno == EINTR);
158
159	/* Remove the entry from the linked list. */
160	if (last == NULL)
161		pidlist = cur->next;
162	else
163		last->next = cur->next;
164	free(cur);
165
166	return (pid == -1 ? -1 : pstat);
167}
168