1*d874cce4Sray /* $OpenBSD: lockf.c,v 1.5 2008/06/26 05:42:05 ray Exp $ */
2246301a8Sderaadt /* $NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $ */
3246301a8Sderaadt
4246301a8Sderaadt /*-
5246301a8Sderaadt * Copyright (c) 1997 The NetBSD Foundation, Inc.
6246301a8Sderaadt * All rights reserved.
7246301a8Sderaadt *
8246301a8Sderaadt * This code is derived from software contributed to The NetBSD Foundation
9246301a8Sderaadt * by Klaus Klein.
10246301a8Sderaadt *
11246301a8Sderaadt * Redistribution and use in source and binary forms, with or without
12246301a8Sderaadt * modification, are permitted provided that the following conditions
13246301a8Sderaadt * are met:
14246301a8Sderaadt * 1. Redistributions of source code must retain the above copyright
15246301a8Sderaadt * notice, this list of conditions and the following disclaimer.
16246301a8Sderaadt * 2. Redistributions in binary form must reproduce the above copyright
17246301a8Sderaadt * notice, this list of conditions and the following disclaimer in the
18246301a8Sderaadt * documentation and/or other materials provided with the distribution.
19246301a8Sderaadt *
20246301a8Sderaadt * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21246301a8Sderaadt * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22246301a8Sderaadt * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23246301a8Sderaadt * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24246301a8Sderaadt * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25246301a8Sderaadt * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26246301a8Sderaadt * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27246301a8Sderaadt * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28246301a8Sderaadt * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29246301a8Sderaadt * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30246301a8Sderaadt * POSSIBILITY OF SUCH DAMAGE.
31246301a8Sderaadt */
32246301a8Sderaadt
33246301a8Sderaadt #include <errno.h>
34246301a8Sderaadt #include <fcntl.h>
35246301a8Sderaadt #include <unistd.h>
36246301a8Sderaadt
37246301a8Sderaadt int
lockf(int filedes,int function,off_t size)38f723aa39Sderaadt lockf(int filedes, int function, off_t size)
39246301a8Sderaadt {
40246301a8Sderaadt struct flock fl;
41246301a8Sderaadt int cmd;
42246301a8Sderaadt
43246301a8Sderaadt fl.l_start = 0;
44246301a8Sderaadt fl.l_len = size;
45246301a8Sderaadt fl.l_whence = SEEK_CUR;
46246301a8Sderaadt
47246301a8Sderaadt switch (function) {
48246301a8Sderaadt case F_ULOCK:
49246301a8Sderaadt cmd = F_SETLK;
50246301a8Sderaadt fl.l_type = F_UNLCK;
51246301a8Sderaadt break;
52246301a8Sderaadt case F_LOCK:
53246301a8Sderaadt cmd = F_SETLKW;
54246301a8Sderaadt fl.l_type = F_WRLCK;
55246301a8Sderaadt break;
56246301a8Sderaadt case F_TLOCK:
57246301a8Sderaadt cmd = F_SETLK;
58246301a8Sderaadt fl.l_type = F_WRLCK;
59246301a8Sderaadt break;
60246301a8Sderaadt case F_TEST:
61246301a8Sderaadt fl.l_type = F_WRLCK;
62246301a8Sderaadt if (fcntl(filedes, F_GETLK, &fl) == -1)
63246301a8Sderaadt return (-1);
64246301a8Sderaadt if (fl.l_type == F_UNLCK || fl.l_pid == getpid())
65246301a8Sderaadt return (0);
66246301a8Sderaadt errno = EAGAIN;
67246301a8Sderaadt return (-1);
68246301a8Sderaadt /* NOTREACHED */
69246301a8Sderaadt default:
70246301a8Sderaadt errno = EINVAL;
71246301a8Sderaadt return (-1);
72246301a8Sderaadt /* NOTREACHED */
73246301a8Sderaadt }
74246301a8Sderaadt
75246301a8Sderaadt return (fcntl(filedes, cmd, &fl));
76246301a8Sderaadt }
77