xref: /illumos-gate/usr/src/cmd/mailx/lock.c (revision 71269a2275bf5a143dad6461eee2710a344e7261)
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, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
23 /*	  All Rights Reserved  	*/
24 
25 
26 /*
27  * University Copyright- Copyright (c) 1982, 1986, 1988
28  * The Regents of the University of California
29  * All Rights Reserved
30  *
31  * University Acknowledgment- Portions of this document are derived from
32  * software developed by the University of California, Berkeley, and its
33  * contributors.
34  */
35 
36 #pragma ident	"%Z%%M%	%I%	%E% SMI"
37 
38 /*
39  * lock a file pointer
40  */
41 
42 #include <stdio.h>
43 #include <string.h>
44 #include <fcntl.h>
45 
46 int
47 lock(FILE *fp, char *mode, int blk)
48 {
49 	struct flock	l;
50 
51 	l.l_type = !strcmp(mode, "r") ? F_RDLCK : F_WRLCK;
52 	l.l_whence = 0;
53 	l.l_start = l.l_len = 0L;
54 	return fcntl(fileno(fp), blk ? F_SETLKW : F_SETLK, &l);
55 }
56