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
41int
42flock(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