2 * Copyright (c) 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software written by Ken Arnold and
6 * published in UNIX Review, Vol. 6, No. 8.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * @(#)popen.c 8.3 (Berkeley) 5/3/95
33 * $FreeBSD: src/lib/libc/gen/popen.c,v 1.20 2008/07/29 16:29:59 ed Exp $
34 * $DragonFly: src/lib/libc/gen/popen.3,v 1.4 2006/04/08 08:17:06 swildner Exp $
37 #include "namespace.h"
38 #include <sys/param.h>
39 #include <sys/queue.h>
51 #include "un-namespace.h"
52 #include "libc_private.h"
54 extern char **environ;
57 SLIST_ENTRY(pid) next;
61 static SLIST_HEAD(, pid) pidlist = SLIST_HEAD_INITIALIZER(pidlist);
62 static pthread_mutex_t pidlist_mutex = PTHREAD_MUTEX_INITIALIZER;
64 #define THREAD_LOCK() if (__isthreaded) _pthread_mutex_lock(&pidlist_mutex)
65 #define THREAD_UNLOCK() if (__isthreaded) _pthread_mutex_unlock(&pidlist_mutex)
68 popen(const char *command, const char *type)
72 int pdes[2], pid, twoway, cloexec;
76 cloexec = (strchr(type, 'e') != NULL);
79 * Lite2 introduced two-way popen() pipes using _socketpair().
80 * FreeBSD's pipe() is bidirectional, so we use that.
82 if (strchr(type, '+')) {
87 if ((*type != 'r' && *type != 'w') ||
88 (type[1] && (type[1] != 'e' || type[2])))
91 if (pipe2(pdes, O_CLOEXEC) < 0)
94 if ((cur = malloc(sizeof(struct pid))) == NULL) {
106 switch (pid = vfork()) {
107 case -1: /* Error. */
117 * The _dup2() to STDIN_FILENO is repeated to avoid
118 * writing to pdes[1], which might corrupt the
119 * parent's copy. This isn't good enough in
120 * general, since the _exit() is no return, so
121 * the compiler is free to corrupt all the local
125 _fcntl(pdes[1], F_SETFD, 0);
126 if (pdes[1] != STDOUT_FILENO) {
127 _dup2(pdes[1], STDOUT_FILENO);
130 _dup2(STDOUT_FILENO, STDIN_FILENO);
131 } else if (twoway && (pdes[1] != STDIN_FILENO))
132 _dup2(pdes[1], STDIN_FILENO);
134 _fcntl(pdes[0], F_SETFD, 0);
135 if (pdes[0] != STDIN_FILENO) {
136 _dup2(pdes[0], STDIN_FILENO);
141 SLIST_FOREACH(p, &pidlist, next)
142 _close(__sfileno(p->fp));
143 _execve(_PATH_BSHELL, __DECONST(char * const *, argv), environ);
149 /* Parent; assume fdopen can't fail. */
151 iop = fdopen(pdes[0], type);
154 iop = fdopen(pdes[1], type);
158 /* Link into list of file descriptors. */
162 SLIST_INSERT_HEAD(&pidlist, cur, next);
166 int fd = (*type == 'r') ? pdes[0] : pdes[1];
167 _fcntl(fd, F_SETFD, 0);
175 * Pclose returns -1 if stream is not associated with a `popened' command,
176 * if already `pclosed', or waitpid returns an error.
181 struct pid *cur, *last = NULL;
186 * Find the appropriate file pointer and remove it from the list.
189 SLIST_FOREACH(cur, &pidlist, next) {
199 SLIST_REMOVE_HEAD(&pidlist, next);
201 SLIST_REMOVE_AFTER(last, next);
203 /* re-apply close-on-exec for unlock/fclose race */
204 _fcntl(__sfileno(iop), F_SETFD, FD_CLOEXEC);
211 pid = _wait4(cur->pid, &pstat, 0, NULL);
212 } while (pid == -1 && errno == EINTR);
216 return (pid == -1 ? -1 : pstat);