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 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 /* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
27 /* All Rights Reserved */
28
29 /*
30 * Portions of this source code were derived from Berkeley 4.3 BSD
31 * under license from the Regents of the University of California.
32 */
33
34 /*LINTLIBRARY*/
35
36 #include <sys/types.h>
37 #include <sys/file.h>
38 #include <sys/fcntl.h>
39 #include <errno.h>
40
41 int
flock(int fd,int operation)42 flock(int fd, int operation)
43 {
44 struct flock fl;
45 int cmd;
46 int ret;
47
48 /* initialize the flock struct to set lock on entire file */
49 fl.l_whence = 0;
50 fl.l_start = 0;
51 fl.l_len = 0;
52 fl.l_type = 0;
53
54 /* In non-blocking lock, use F_SETLK for cmd, F_SETLKW otherwise */
55 if (operation & LOCK_NB) {
56 cmd = F_SETLK;
57 operation &= ~LOCK_NB; /* turn off this bit */
58 } else
59 cmd = F_SETLKW;
60
61 switch (operation) {
62 case LOCK_UN:
63 fl.l_type |= F_UNLCK;
64 break;
65 case LOCK_SH:
66 fl.l_type |= F_RDLCK;
67 break;
68 case LOCK_EX:
69 fl.l_type |= F_WRLCK;
70 break;
71 default:
72 errno = EINVAL;
73 return (-1);
74 }
75
76 ret = fcntl(fd, cmd, &fl);
77
78 if (ret == -1 && errno == EACCES)
79 errno = EWOULDBLOCK;
80
81 return (ret);
82 }
83