1 /* $NetBSD: popen.c,v 1.35 2015/02/02 22:07:05 christos 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 1.35 2015/02/02 22:07:05 christos 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
61 #ifdef __weak_alias
62 __weak_alias(popen,_popen)
63 __weak_alias(pclose,_pclose)
64 #endif
65
66 static struct pid {
67 struct pid *next;
68 FILE *fp;
69 #ifdef _REENTRANT
70 int fd;
71 #endif
72 pid_t pid;
73 } *pidlist;
74
75 #ifdef _REENTRANT
76 static rwlock_t pidlist_lock = RWLOCK_INITIALIZER;
77 #endif
78
79 static struct pid *
pdes_get(int * pdes,const char ** type)80 pdes_get(int *pdes, const char **type)
81 {
82 struct pid *cur;
83 int flags = strchr(*type, 'e') ? O_CLOEXEC : 0;
84 int serrno;
85
86 if (strchr(*type, '+')) {
87 int stype = flags ? (SOCK_STREAM | SOCK_CLOEXEC) : SOCK_STREAM;
88 *type = "r+";
89 if (socketpair(AF_LOCAL, stype, 0, pdes) < 0)
90 return NULL;
91 } else {
92 *type = strrchr(*type, 'r') ? "r" : "w";
93 if (pipe2(pdes, flags) == -1)
94 return NULL;
95 }
96
97 if ((cur = malloc(sizeof(*cur))) != NULL)
98 return cur;
99 serrno = errno;
100 (void)close(pdes[0]);
101 (void)close(pdes[1]);
102 errno = serrno;
103 return NULL;
104 }
105
106 static void
pdes_child(int * pdes,const char * type)107 pdes_child(int *pdes, const char *type)
108 {
109 struct pid *old;
110
111 /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams
112 from previous popen() calls that remain open in the
113 parent process are closed in the new child process. */
114 for (old = pidlist; old; old = old->next)
115 #ifdef _REENTRANT
116 (void)close(old->fd); /* don't allow a flush */
117 #else
118 (void)close(fileno(old->fp)); /* don't allow a flush */
119 #endif
120
121 if (type[0] == 'r') {
122 (void)close(pdes[0]);
123 if (pdes[1] != STDOUT_FILENO) {
124 (void)dup2(pdes[1], STDOUT_FILENO);
125 (void)close(pdes[1]);
126 }
127 if (type[1] == '+')
128 (void)dup2(STDOUT_FILENO, STDIN_FILENO);
129 } else {
130 (void)close(pdes[1]);
131 if (pdes[0] != STDIN_FILENO) {
132 (void)dup2(pdes[0], STDIN_FILENO);
133 (void)close(pdes[0]);
134 }
135 }
136 }
137
138 static void
pdes_parent(int * pdes,struct pid * cur,pid_t pid,const char * type)139 pdes_parent(int *pdes, struct pid *cur, pid_t pid, const char *type)
140 {
141 FILE *iop;
142
143 /* Parent; assume fdopen can't fail. */
144 if (*type == 'r') {
145 iop = fdopen(pdes[0], type);
146 #ifdef _REENTRANT
147 cur->fd = pdes[0];
148 #endif
149 (void)close(pdes[1]);
150 } else {
151 iop = fdopen(pdes[1], type);
152 #ifdef _REENTRANT
153 cur->fd = pdes[1];
154 #endif
155 (void)close(pdes[0]);
156 }
157
158 /* Link into list of file descriptors. */
159 cur->fp = iop;
160 cur->pid = pid;
161 cur->next = pidlist;
162 pidlist = cur;
163 }
164
165 static void
pdes_error(int * pdes,struct pid * cur)166 pdes_error(int *pdes, struct pid *cur)
167 {
168 free(cur);
169 (void)close(pdes[0]);
170 (void)close(pdes[1]);
171 }
172
173 FILE *
popen(const char * cmd,const char * type)174 popen(const char *cmd, const char *type)
175 {
176 struct pid *cur;
177 int pdes[2], serrno;
178 pid_t pid;
179
180 _DIAGASSERT(cmd != NULL);
181 _DIAGASSERT(type != NULL);
182
183 if ((cur = pdes_get(pdes, &type)) == NULL)
184 return NULL;
185
186 #ifdef _REENTRANT
187 (void)rwlock_rdlock(&pidlist_lock);
188 #endif
189 (void)__readlockenv();
190 switch (pid = vfork()) {
191 case -1: /* Error. */
192 serrno = errno;
193 (void)__unlockenv();
194 #ifdef _REENTRANT
195 (void)rwlock_unlock(&pidlist_lock);
196 #endif
197 pdes_error(pdes, cur);
198 errno = serrno;
199 return NULL;
200 /* NOTREACHED */
201 case 0: /* Child. */
202 pdes_child(pdes, type);
203 execl(_PATH_BSHELL, "sh", "-c", cmd, NULL);
204 _exit(127);
205 /* NOTREACHED */
206 }
207 (void)__unlockenv();
208
209 pdes_parent(pdes, cur, pid, type);
210
211 #ifdef _REENTRANT
212 (void)rwlock_unlock(&pidlist_lock);
213 #endif
214
215 return cur->fp;
216 }
217
218 FILE *
popenve(const char * cmd,char * const * argv,char * const * envp,const char * type)219 popenve(const char *cmd, char *const *argv, char *const *envp, const char *type)
220 {
221 struct pid *cur;
222 int pdes[2], serrno;
223 pid_t pid;
224
225 _DIAGASSERT(cmd != NULL);
226 _DIAGASSERT(type != NULL);
227
228 if ((cur = pdes_get(pdes, &type)) == NULL)
229 return NULL;
230
231 #ifdef _REENTRANT
232 (void)rwlock_rdlock(&pidlist_lock);
233 #endif
234 switch (pid = vfork()) {
235 case -1: /* Error. */
236 serrno = errno;
237 #ifdef _REENTRANT
238 (void)rwlock_unlock(&pidlist_lock);
239 #endif
240 pdes_error(pdes, cur);
241 errno = serrno;
242 return NULL;
243 /* NOTREACHED */
244 case 0: /* Child. */
245 pdes_child(pdes, type);
246 execve(cmd, argv, envp);
247 _exit(127);
248 /* NOTREACHED */
249 }
250
251 pdes_parent(pdes, cur, pid, type);
252
253 #ifdef _REENTRANT
254 (void)rwlock_unlock(&pidlist_lock);
255 #endif
256
257 return cur->fp;
258 }
259
260 /*
261 * pclose --
262 * Pclose returns -1 if stream is not associated with a `popened' command,
263 * if already `pclosed', or waitpid returns an error.
264 */
265 int
pclose(FILE * iop)266 pclose(FILE *iop)
267 {
268 struct pid *cur, *last;
269 int pstat;
270 pid_t pid;
271
272 _DIAGASSERT(iop != NULL);
273
274 #ifdef _REENTRANT
275 rwlock_wrlock(&pidlist_lock);
276 #endif
277
278 /* Find the appropriate file pointer. */
279 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
280 if (cur->fp == iop)
281 break;
282 if (cur == NULL) {
283 #ifdef _REENTRANT
284 (void)rwlock_unlock(&pidlist_lock);
285 #endif
286 errno = ESRCH;
287 return -1;
288 }
289
290 (void)fclose(iop);
291
292 /* Remove the entry from the linked list. */
293 if (last == NULL)
294 pidlist = cur->next;
295 else
296 last->next = cur->next;
297
298 #ifdef _REENTRANT
299 (void)rwlock_unlock(&pidlist_lock);
300 #endif
301
302 do {
303 pid = waitpid(cur->pid, &pstat, 0);
304 } while (pid == -1 && errno == EINTR);
305
306 free(cur);
307
308 return pid == -1 ? -1 : pstat;
309 }
310