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 FILE *
popen(const char * program,const char * type)52 popen(const char *program, const char *type)
53 {
54 struct pid * volatile cur;
55 FILE *iop;
56 int pdes[2];
57 pid_t pid;
58
59 if ((*type != 'r' && *type != 'w') || type[1] != '\0') {
60 errno = EINVAL;
61 return (NULL);
62 }
63
64 if ((cur = malloc(sizeof(struct pid))) == NULL)
65 return (NULL);
66
67 if (pipe(pdes) < 0) {
68 free(cur);
69 return (NULL);
70 }
71
72 switch (pid = vfork()) {
73 case -1: /* Error. */
74 (void)close(pdes[0]);
75 (void)close(pdes[1]);
76 free(cur);
77 return (NULL);
78 /* NOTREACHED */
79 case 0: /* Child. */
80 {
81 struct pid *pcur;
82 /*
83 * because vfork() instead of fork(), must leak FILE *,
84 * but luckily we are terminally headed for an execl()
85 */
86 for (pcur = pidlist; pcur; pcur = pcur->next)
87 close(fileno(pcur->fp));
88
89 if (*type == 'r') {
90 int tpdes1 = pdes[1];
91
92 (void) close(pdes[0]);
93 /*
94 * We must NOT modify pdes, due to the
95 * semantics of vfork.
96 */
97 if (tpdes1 != STDOUT_FILENO) {
98 (void)dup2(tpdes1, STDOUT_FILENO);
99 (void)close(tpdes1);
100 tpdes1 = STDOUT_FILENO;
101 }
102 } else {
103 (void)close(pdes[1]);
104 if (pdes[0] != STDIN_FILENO) {
105 (void)dup2(pdes[0], STDIN_FILENO);
106 (void)close(pdes[0]);
107 }
108 }
109 execl(_PATH_BSHELL, "sh", "-c", program, (char *)NULL);
110 _exit(127);
111 /* NOTREACHED */
112 }
113 }
114
115 /* Parent; assume fdopen can't fail. */
116 if (*type == 'r') {
117 iop = fdopen(pdes[0], type);
118 (void)close(pdes[1]);
119 } else {
120 iop = fdopen(pdes[1], type);
121 (void)close(pdes[0]);
122 }
123
124 /* Link into list of file descriptors. */
125 cur->fp = iop;
126 cur->pid = pid;
127 cur->next = pidlist;
128 pidlist = cur;
129
130 return (iop);
131 }
132
133 /*
134 * pclose --
135 * Pclose returns -1 if stream is not associated with a `popened' command,
136 * if already `pclosed', or waitpid returns an error.
137 */
138 int
pclose(FILE * iop)139 pclose(FILE *iop)
140 {
141 struct pid *cur, *last;
142 int pstat;
143 pid_t pid;
144
145 /* Find the appropriate file pointer. */
146 for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
147 if (cur->fp == iop)
148 break;
149
150 if (cur == NULL)
151 return (-1);
152
153 (void)fclose(iop);
154
155 do {
156 pid = waitpid(cur->pid, &pstat, 0);
157 } while (pid == -1 && errno == EINTR);
158
159 /* Remove the entry from the linked list. */
160 if (last == NULL)
161 pidlist = cur->next;
162 else
163 last->next = cur->next;
164 free(cur);
165
166 return (pid == -1 ? -1 : pstat);
167 }
168