1 /* $OpenBSD: popen.c,v 1.22 2019/06/28 13:32:41 deraadt Exp $ */
2 /*
3 * Copyright (c) 1988, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software written by Ken Arnold and
7 * published in UNIX Review, Vol. 6, No. 8.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <sys/wait.h>
35
36 #include <signal.h>
37 #include <errno.h>
38 #include <fcntl.h>
39 #include <unistd.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <paths.h>
44 #include <wchar.h>
45 #include "thread_private.h"
46
47 static struct pid {
48 struct pid *next;
49 FILE *fp;
50 pid_t pid;
51 } *pidlist;
52
53 static void *pidlist_lock = NULL;
54
55 FILE *
popen(const char * program,const char * type)56 popen(const char *program, const char *type)
57 {
58 struct pid * volatile cur;
59 FILE *iop;
60 int pdes[2];
61 int target;
62 pid_t pid;
63
64 if ((*type != 'r' && *type != 'w') ||
65 (type[1] != '\0' && (type[1] != 'e' || type[2] != '\0'))) {
66 errno = EINVAL;
67 return (NULL);
68 }
69
70 if ((cur = malloc(sizeof(struct pid))) == NULL)
71 return (NULL);
72
73 if (pipe2(pdes, O_CLOEXEC) == -1) {
74 free(cur);
75 return (NULL);
76 }
77
78 _MUTEX_LOCK(&pidlist_lock);
79 switch (pid = vfork()) {
80 case -1: /* Error. */
81 _MUTEX_UNLOCK(&pidlist_lock);
82 (void)close(pdes[0]);
83 (void)close(pdes[1]);
84 free(cur);
85 return (NULL);
86 /* NOTREACHED */
87 case 0: /* Child. */
88 {
89 struct pid *pcur;
90
91 /*
92 * because vfork() instead of fork(), must leak FILE *,
93 * but luckily we are terminally headed for an execl()
94 */
95 for (pcur = pidlist; pcur; pcur = pcur->next)
96 close(fileno(pcur->fp));
97
98 target = *type == 'r';
99 if (pdes[target] != target) {
100 if (dup2(pdes[target], target) == -1)
101 _exit(127);
102 } else {
103 int flags = fcntl(pdes[target], F_GETFD);
104 if (flags == -1 || ((flags & FD_CLOEXEC) &&
105 fcntl(pdes[target], F_SETFD, flags & ~FD_CLOEXEC)
106 == -1))
107 _exit(127);
108 }
109
110 execl(_PATH_BSHELL, "sh", "-c", program, (char *)NULL);
111 _exit(127);
112 /* NOTREACHED */
113 }
114 }
115 _MUTEX_UNLOCK(&pidlist_lock);
116
117 /* Parent; assume fdopen can't fail. */
118 target = *type == 'w';
119 iop = fdopen(pdes[target], type);
120 fwide(iop, -1);
121 (void)close(pdes[!target]);
122
123 /* Link into list of file descriptors. */
124 cur->fp = iop;
125 cur->pid = pid;
126 _MUTEX_LOCK(&pidlist_lock);
127 cur->next = pidlist;
128 pidlist = cur;
129 _MUTEX_UNLOCK(&pidlist_lock);
130
131 /* now that it's in the list, clear FD_CLOEXEC if unwanted */
132 if (type[1] != 'e') {
133 int flags = fcntl(pdes[target], F_GETFD);
134 if (flags != -1)
135 fcntl(pdes[target], F_SETFD, flags & ~FD_CLOEXEC);
136 }
137
138 return (iop);
139 }
140 DEF_WEAK(popen);
141
142 /*
143 * pclose --
144 * Pclose returns -1 if stream is not associated with a `popened' command,
145 * if already `pclosed', or waitpid returns an error.
146 */
147 int
pclose(FILE * iop)148 pclose(FILE *iop)
149 {
150 struct pid *cur, *last;
151 int pstat;
152 pid_t pid;
153
154 /* Find the appropriate file pointer. */
155 _MUTEX_LOCK(&pidlist_lock);
156 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
157 if (cur->fp == iop)
158 break;
159
160 if (cur == NULL) {
161 _MUTEX_UNLOCK(&pidlist_lock);
162 return (-1);
163 }
164
165 /* Remove the entry from the linked list. */
166 if (last == NULL)
167 pidlist = cur->next;
168 else
169 last->next = cur->next;
170 _MUTEX_UNLOCK(&pidlist_lock);
171
172 (void)fclose(iop);
173
174 do {
175 pid = waitpid(cur->pid, &pstat, 0);
176 } while (pid == -1 && errno == EINTR);
177
178 free(cur);
179
180 return (pid == -1 ? -1 : pstat);
181 }
182 DEF_WEAK(pclose);
183