Annotation of src/lib/libc/gen/popen.c, Revision 1.9
1.1 cgd 1: /*
1.7 jtc 2: * Copyright (c) 1988, 1993
3: * The Regents of the University of California. All rights reserved.
1.1 cgd 4: *
5: * This code is derived from software written by Ken Arnold and
6: * published in UNIX Review, Vol. 6, No. 8.
7: *
8: * Redistribution and use in source and binary forms, with or without
9: * modification, are permitted provided that the following conditions
10: * are met:
11: * 1. Redistributions of source code must retain the above copyright
12: * notice, this list of conditions and the following disclaimer.
13: * 2. Redistributions in binary form must reproduce the above copyright
14: * notice, this list of conditions and the following disclaimer in the
15: * documentation and/or other materials provided with the distribution.
16: * 3. All advertising materials mentioning features or use of this software
17: * must display the following acknowledgement:
18: * This product includes software developed by the University of
19: * California, Berkeley and its contributors.
20: * 4. Neither the name of the University nor the names of its contributors
21: * may be used to endorse or promote products derived from this software
22: * without specific prior written permission.
23: *
24: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34: * SUCH DAMAGE.
35: */
36:
37: #if defined(LIBC_SCCS) && !defined(lint)
1.9 ! jtc 38: /* static char sccsid[] = "@(#)popen.c 8.1 (Berkeley) 6/4/93"; */
! 39: static char *rcsid = "$Id: $";
1.1 cgd 40: #endif /* LIBC_SCCS and not lint */
41:
42: #include <sys/param.h>
43: #include <sys/wait.h>
1.7 jtc 44:
45: #include <signal.h>
1.1 cgd 46: #include <errno.h>
1.7 jtc 47: #include <unistd.h>
1.1 cgd 48: #include <stdio.h>
49: #include <stdlib.h>
50: #include <string.h>
51: #include <paths.h>
52:
1.7 jtc 53: static struct pid {
54: struct pid *next;
55: FILE *fp;
56: pid_t pid;
57: } *pidlist;
58:
1.1 cgd 59: FILE *
1.8 cgd 60: popen(program, type)
61: const char *program;
1.1 cgd 62: const char *type;
63: {
1.7 jtc 64: struct pid *cur;
1.1 cgd 65: FILE *iop;
1.7 jtc 66: int pdes[2], pid;
1.1 cgd 67:
1.9 ! jtc 68: if (*type != 'r' && *type != 'w' || type[1]) {
! 69: errno = EINVAL;
1.1 cgd 70: return (NULL);
1.9 ! jtc 71: }
1.1 cgd 72:
1.7 jtc 73: if ((cur = malloc(sizeof(struct pid))) == NULL)
74: return (NULL);
75:
76: if (pipe(pdes) < 0) {
77: (void)free(cur);
78: return (NULL);
1.1 cgd 79: }
1.7 jtc 80:
1.1 cgd 81: switch (pid = vfork()) {
1.7 jtc 82: case -1: /* Error. */
83: (void)close(pdes[0]);
84: (void)close(pdes[1]);
85: (void)free(cur);
1.1 cgd 86: return (NULL);
87: /* NOTREACHED */
1.7 jtc 88: case 0: /* Child. */
1.1 cgd 89: if (*type == 'r') {
90: if (pdes[1] != STDOUT_FILENO) {
1.7 jtc 91: (void)dup2(pdes[1], STDOUT_FILENO);
92: (void)close(pdes[1]);
1.1 cgd 93: }
94: (void) close(pdes[0]);
95: } else {
96: if (pdes[0] != STDIN_FILENO) {
1.7 jtc 97: (void)dup2(pdes[0], STDIN_FILENO);
98: (void)close(pdes[0]);
1.1 cgd 99: }
1.7 jtc 100: (void)close(pdes[1]);
1.1 cgd 101: }
1.9 ! jtc 102: execl(_PATH_BSHELL, "sh", "-c", program, (char *) 0);
1.1 cgd 103: _exit(127);
104: /* NOTREACHED */
105: }
1.7 jtc 106:
107: /* Parent; assume fdopen can't fail. */
1.1 cgd 108: if (*type == 'r') {
109: iop = fdopen(pdes[0], type);
1.7 jtc 110: (void)close(pdes[1]);
1.1 cgd 111: } else {
112: iop = fdopen(pdes[1], type);
1.7 jtc 113: (void)close(pdes[0]);
1.1 cgd 114: }
1.7 jtc 115:
116: /* Link into list of file descriptors. */
117: cur->fp = iop;
118: cur->pid = pid;
119: cur->next = pidlist;
120: pidlist = cur;
121:
1.1 cgd 122: return (iop);
123: }
124:
1.7 jtc 125: /*
126: * pclose --
127: * Pclose returns -1 if stream is not associated with a `popened' command,
128: * if already `pclosed', or waitpid returns an error.
129: */
1.1 cgd 130: int
131: pclose(iop)
132: FILE *iop;
133: {
1.7 jtc 134: register struct pid *cur, *last;
1.9 ! jtc 135: int pstat;
1.1 cgd 136: pid_t pid;
137:
1.8 cgd 138: (void)fclose(iop);
139:
1.7 jtc 140: /* Find the appropriate file pointer. */
141: for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next)
142: if (cur->fp == iop)
143: break;
144: if (cur == NULL)
1.1 cgd 145: return (-1);
1.7 jtc 146:
1.1 cgd 147: do {
1.9 ! jtc 148: pid = waitpid(cur->pid, &pstat, 0);
1.1 cgd 149: } while (pid == -1 && errno == EINTR);
1.7 jtc 150:
151: /* Remove the entry from the linked list. */
152: if (last == NULL)
153: pidlist = cur->next;
154: else
155: last->next = cur->next;
156: free(cur);
157:
1.9 ! jtc 158: return (pid == -1 ? -1 : pstat);
1.1 cgd 159: }
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