1/*	$NetBSD: popen.c,v 1.32 2012/06/25 22:32:43 abs 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. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#if defined(LIBC_SCCS) && !defined(lint)
37#if 0
38static char sccsid[] = "@(#)popen.c	8.3 (Berkeley) 5/3/95";
39#else
40__RCSID("$NetBSD: popen.c,v 1.32 2012/06/25 22:32:43 abs Exp $");
41#endif
42#endif /* LIBC_SCCS and not lint */
43
44#include "namespace.h"
45#include <sys/param.h>
46#include <sys/wait.h>
47#include <sys/socket.h>
48
49#include <assert.h>
50#include <errno.h>
51#include <paths.h>
52#include <signal.h>
53#include <stdio.h>
54#include <stdlib.h>
55#include <string.h>
56#include <unistd.h>
57#include <fcntl.h>
58
59#include "env.h"
60#include "reentrant.h"
61
62#ifdef __weak_alias
63__weak_alias(popen,_popen)
64__weak_alias(pclose,_pclose)
65#endif
66
67static struct pid {
68	struct pid *next;
69	FILE *fp;
70#ifdef _REENTRANT
71	int fd;
72#endif
73	pid_t pid;
74} *pidlist;
75
76#ifdef _REENTRANT
77static rwlock_t pidlist_lock = RWLOCK_INITIALIZER;
78#endif
79
80FILE *
81popen(const char *command, const char *type)
82{
83	struct pid *cur, *old;
84	FILE *iop;
85	const char * volatile xtype = type;
86	int pdes[2], pid, serrno;
87	volatile int twoway;
88	int flags;
89
90	_DIAGASSERT(command != NULL);
91	_DIAGASSERT(xtype != NULL);
92
93	flags = strchr(xtype, 'e') ? O_CLOEXEC : 0;
94	if (strchr(xtype, '+')) {
95		int stype = flags ? (SOCK_STREAM | SOCK_CLOEXEC) : SOCK_STREAM;
96		twoway = 1;
97		xtype = "r+";
98		if (socketpair(AF_LOCAL, stype, 0, pdes) < 0)
99			return NULL;
100	} else  {
101		twoway = 0;
102		xtype = strrchr(xtype, 'r') ? "r" : "w";
103		if (pipe2(pdes, flags) == -1)
104			return NULL;
105	}
106
107	if ((cur = malloc(sizeof(struct pid))) == NULL) {
108		(void)close(pdes[0]);
109		(void)close(pdes[1]);
110		errno = ENOMEM;
111		return (NULL);
112	}
113
114	(void)rwlock_rdlock(&pidlist_lock);
115	(void)__readlockenv();
116	switch (pid = vfork()) {
117	case -1:			/* Error. */
118		serrno = errno;
119		(void)__unlockenv();
120		(void)rwlock_unlock(&pidlist_lock);
121		free(cur);
122		(void)close(pdes[0]);
123		(void)close(pdes[1]);
124		errno = serrno;
125		return (NULL);
126		/* NOTREACHED */
127	case 0:				/* Child. */
128		/* POSIX.2 B.3.2.2 "popen() shall ensure that any streams
129		   from previous popen() calls that remain open in the
130		   parent process are closed in the new child process. */
131		for (old = pidlist; old; old = old->next)
132#ifdef _REENTRANT
133			close(old->fd); /* don't allow a flush */
134#else
135			close(fileno(old->fp)); /* don't allow a flush */
136#endif
137
138		if (*xtype == 'r') {
139			(void)close(pdes[0]);
140			if (pdes[1] != STDOUT_FILENO) {
141				(void)dup2(pdes[1], STDOUT_FILENO);
142				(void)close(pdes[1]);
143			}
144			if (twoway)
145				(void)dup2(STDOUT_FILENO, STDIN_FILENO);
146		} else {
147			(void)close(pdes[1]);
148			if (pdes[0] != STDIN_FILENO) {
149				(void)dup2(pdes[0], STDIN_FILENO);
150				(void)close(pdes[0]);
151			}
152		}
153
154		execl(_PATH_BSHELL, "sh", "-c", command, NULL);
155		_exit(127);
156		/* NOTREACHED */
157	}
158	(void)__unlockenv();
159
160	/* Parent; assume fdopen can't fail. */
161	if (*xtype == 'r') {
162		iop = fdopen(pdes[0], xtype);
163#ifdef _REENTRANT
164		cur->fd = pdes[0];
165#endif
166		(void)close(pdes[1]);
167	} else {
168		iop = fdopen(pdes[1], xtype);
169#ifdef _REENTRANT
170		cur->fd = pdes[1];
171#endif
172		(void)close(pdes[0]);
173	}
174
175	/* Link into list of file descriptors. */
176	cur->fp = iop;
177	cur->pid =  pid;
178	cur->next = pidlist;
179	pidlist = cur;
180	(void)rwlock_unlock(&pidlist_lock);
181
182	return (iop);
183}
184
185/*
186 * pclose --
187 *	Pclose returns -1 if stream is not associated with a `popened' command,
188 *	if already `pclosed', or waitpid returns an error.
189 */
190int
191pclose(FILE *iop)
192{
193	struct pid *cur, *last;
194	int pstat;
195	pid_t pid;
196
197	_DIAGASSERT(iop != NULL);
198
199	rwlock_wrlock(&pidlist_lock);
200
201	/* Find the appropriate file pointer. */
202	for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
203		if (cur->fp == iop)
204			break;
205	if (cur == NULL) {
206		(void)rwlock_unlock(&pidlist_lock);
207		return (-1);
208	}
209
210	(void)fclose(iop);
211
212	/* Remove the entry from the linked list. */
213	if (last == NULL)
214		pidlist = cur->next;
215	else
216		last->next = cur->next;
217
218	(void)rwlock_unlock(&pidlist_lock);
219
220	do {
221		pid = waitpid(cur->pid, &pstat, 0);
222	} while (pid == -1 && errno == EINTR);
223
224	free(cur);
225
226	return (pid == -1 ? -1 : pstat);
227}
228