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
38 static 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
67 static 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
77 static rwlock_t pidlist_lock = RWLOCK_INITIALIZER;
78 #endif
79
80 FILE *
popen(const char * command,const char * type)81 popen(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 */
190 int
pclose(FILE * iop)191 pclose(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