1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #pragma ident "%Z%%M% %I% %E% SMI"
28
29 #include <fcntl.h>
30 #include <unistd.h>
31 #include <sys/syscall.h>
32 #include <errno.h>
33
34 #define OPEN_MAX 20 /* Taken from SVR4 limits.h */
35
36 int
dup2(int fildes,int fildes2)37 dup2(
38 int fildes, /* file descriptor to be duplicated */
39 int fildes2) /* desired file descriptor */
40 {
41 int tmperrno; /* local work area */
42 int open_max; /* max open files */
43 int ret; /* return value */
44 int fds; /* duplicate files descriptor */
45
46 if ((open_max = ulimit(4, 0)) < 0)
47 open_max = OPEN_MAX; /* take a guess */
48
49 /* Be sure fildes is valid and open */
50 if (fcntl(fildes, F_GETFL, 0) == -1) {
51 errno = EBADF;
52 return (-1);
53 }
54
55 /* Be sure fildes2 is in valid range */
56 if (fildes2 < 0 || fildes2 >= open_max) {
57 errno = EBADF;
58 return (-1);
59 }
60
61 /* Check if file descriptors are equal */
62 if (fildes == fildes2) {
63 /* open and equal so no dup necessary */
64 return (fildes2);
65 }
66 /* Close in case it was open for another file */
67 /* Must save and restore errno in case file was not open */
68 tmperrno = errno;
69 close(fildes2);
70 errno = tmperrno;
71
72 /* Do the dup */
73 if ((ret = fcntl(fildes, F_DUPFD, fildes2)) != -1) {
74 if ((fds = fd_get(fildes)) != -1)
75 fd_add(fildes2, fds);
76 }
77 return (ret);
78 }
79