1 /* $OpenBSD: popen.c,v 1.17 2005/08/08 08:05:34 espie 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/param.h>
35 #include <sys/wait.h>
36
37 #include <signal.h>
38 #include <errno.h>
39 #include <unistd.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <paths.h>
44
45 static struct pid {
46 struct pid *next;
47 FILE *fp;
48 pid_t pid;
49 } *pidlist;
50
51 extern char **environ;
52
53 FILE *
popen(const char * program,const char * type)54 popen(const char *program, const char *type)
55 {
56 struct pid * volatile cur;
57 FILE *iop;
58 int pdes[2];
59 pid_t pid;
60 char *argp[] = {"sh", "-c", NULL, NULL};
61
62 if ((*type != 'r' && *type != 'w') || type[1] != '\0') {
63 errno = EINVAL;
64 return (NULL);
65 }
66
67 if ((cur = malloc(sizeof(struct pid))) == NULL)
68 return (NULL);
69
70 if (pipe(pdes) < 0) {
71 free(cur);
72 return (NULL);
73 }
74
75 switch (pid = fork()) {
76 case -1: /* Error. */
77 (void)close(pdes[0]);
78 (void)close(pdes[1]);
79 free(cur);
80 return (NULL);
81 /* NOTREACHED */
82 case 0: /* Child. */
83 {
84 struct pid *pcur;
85 /*
86 * We fork()'d, we got our own copy of the list, no
87 * contention.
88 */
89 for (pcur = pidlist; pcur; pcur = pcur->next)
90 close(fileno(pcur->fp));
91
92 if (*type == 'r') {
93 (void) close(pdes[0]);
94 if (pdes[1] != STDOUT_FILENO) {
95 (void)dup2(pdes[1], STDOUT_FILENO);
96 (void)close(pdes[1]);
97 }
98 } else {
99 (void)close(pdes[1]);
100 if (pdes[0] != STDIN_FILENO) {
101 (void)dup2(pdes[0], STDIN_FILENO);
102 (void)close(pdes[0]);
103 }
104 }
105 argp[2] = (char *)program;
106 execve(_PATH_BSHELL, argp, environ);
107 _exit(127);
108 /* NOTREACHED */
109 }
110 }
111
112 /* Parent; assume fdopen can't fail. */
113 if (*type == 'r') {
114 iop = fdopen(pdes[0], type);
115 (void)close(pdes[1]);
116 } else {
117 iop = fdopen(pdes[1], type);
118 (void)close(pdes[0]);
119 }
120
121 /* Link into list of file descriptors. */
122 cur->fp = iop;
123 cur->pid = pid;
124 cur->next = pidlist;
125 pidlist = cur;
126
127 return (iop);
128 }
129
130 /*
131 * pclose --
132 * Pclose returns -1 if stream is not associated with a `popened' command,
133 * if already `pclosed', or waitpid returns an error.
134 */
135 int
pclose(FILE * iop)136 pclose(FILE *iop)
137 {
138 struct pid *cur, *last;
139 int pstat;
140 pid_t pid;
141
142 /* Find the appropriate file pointer. */
143 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
144 if (cur->fp == iop)
145 break;
146
147 if (cur == NULL)
148 return (-1);
149
150 (void)fclose(iop);
151
152 do {
153 pid = waitpid(cur->pid, &pstat, 0);
154 } while (pid == -1 && errno == EINTR);
155
156 /* Remove the entry from the linked list. */
157 if (last == NULL)
158 pidlist = cur->next;
159 else
160 last->next = cur->next;
161 free(cur);
162
163 return (pid == -1 ? -1 : pstat);
164 }
165