xref: /illumos-gate/usr/src/ucblib/libucb/port/sys/flock.c (revision 7a5aac98)
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  * Copyright 2015 Joyent, Inc.
25  */
26 
27 /*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
28 /*	  All Rights Reserved  	*/
29 
30 /*
31  * Portions of this source code were derived from Berkeley 4.3 BSD
32  * under license from the Regents of the University of California.
33  */
34 
35 /*LINTLIBRARY*/
36 
37 #include <sys/types.h>
38 #include <sys/file.h>
39 #include <sys/fcntl.h>
40 #include <errno.h>
41 
42 int
flock(int fd,int operation)43 flock(int fd, int operation)
44 {
45 	struct flock	fl;
46 	int	cmd;
47 	int	ret;
48 
49 	/* initialize the flock struct to set lock on entire file */
50 	fl.l_whence = 0;
51 	fl.l_start = 0;
52 	fl.l_len = 0;
53 	fl.l_type = 0;
54 
55 	if (operation & LOCK_NB) {
56 		cmd = F_FLOCK;
57 		operation &= ~LOCK_NB;	/* turn off this bit */
58 	} else
59 		cmd = F_FLOCKW;
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