1 /* $OpenBSD: lockf.c,v 1.5 2008/06/26 05:42:05 ray Exp $ */
2 /* $NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $ */
3
4 /*-
5 * Copyright (c) 1997 The NetBSD Foundation, Inc.
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to The NetBSD Foundation
9 * by Klaus Klein.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #include <errno.h>
34 #include <fcntl.h>
35 #include <unistd.h>
36
37 int
lockf(int filedes,int function,off_t size)38 lockf(int filedes, int function, off_t size)
39 {
40 struct flock fl;
41 int cmd;
42
43 fl.l_start = 0;
44 fl.l_len = size;
45 fl.l_whence = SEEK_CUR;
46
47 switch (function) {
48 case F_ULOCK:
49 cmd = F_SETLK;
50 fl.l_type = F_UNLCK;
51 break;
52 case F_LOCK:
53 cmd = F_SETLKW;
54 fl.l_type = F_WRLCK;
55 break;
56 case F_TLOCK:
57 cmd = F_SETLK;
58 fl.l_type = F_WRLCK;
59 break;
60 case F_TEST:
61 fl.l_type = F_WRLCK;
62 if (fcntl(filedes, F_GETLK, &fl) == -1)
63 return (-1);
64 if (fl.l_type == F_UNLCK || fl.l_pid == getpid())
65 return (0);
66 errno = EAGAIN;
67 return (-1);
68 /* NOTREACHED */
69 default:
70 errno = EINVAL;
71 return (-1);
72 /* NOTREACHED */
73 }
74
75 return (fcntl(filedes, cmd, &fl));
76 }
77