1 /* $NetBSD: lockf.c,v 1.4 2012/06/25 22:32:43 abs Exp $ */
2
3 /*-
4 * Copyright (c) 1997 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Klaus Klein.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 __RCSID("$NetBSD: lockf.c,v 1.4 2012/06/25 22:32:43 abs Exp $");
35 #endif
36
37 #include "namespace.h"
38 #include <errno.h>
39 #include <fcntl.h>
40 #include <unistd.h>
41
42 #ifdef __weak_alias
__weak_alias(lockf,_lockf)43 __weak_alias(lockf,_lockf)
44 #endif
45
46
47 int
48 lockf(int filedes, int function, off_t size)
49 {
50 struct flock fl;
51 int cmd;
52
53 fl.l_start = 0;
54 fl.l_len = size;
55 fl.l_whence = SEEK_CUR;
56
57 switch (function) {
58 case F_ULOCK:
59 cmd = F_SETLK;
60 fl.l_type = F_UNLCK;
61 break;
62 case F_LOCK:
63 cmd = F_SETLKW;
64 fl.l_type = F_WRLCK;
65 break;
66 case F_TLOCK:
67 cmd = F_SETLK;
68 fl.l_type = F_WRLCK;
69 break;
70 case F_TEST:
71 fl.l_type = F_WRLCK;
72 if (fcntl(filedes, F_GETLK, &fl) == -1)
73 return (-1);
74 if (fl.l_type == F_UNLCK || fl.l_pid == getpid())
75 return (0);
76 errno = EAGAIN;
77 return (-1);
78 /* NOTREACHED */
79 default:
80 errno = EINVAL;
81 return (-1);
82 /* NOTREACHED */
83 }
84
85 return (fcntl(filedes, cmd, &fl));
86 }
87