lockf.c revision 81586 
1/*	$NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink 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 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *        This product includes software developed by the NetBSD
21 *        Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 *    contributors may be used to endorse or promote products derived
24 *    from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39#if defined(LIBC_SCCS) && !defined(lint)
40static const char rcsid[]=
41  "$FreeBSD: head/lib/libc/gen/lockf.c 81586 2001-08-13 14:06:34Z ru $";
42#endif
43
44#include "namespace.h"
45#include <errno.h>
46#include <fcntl.h>
47#include <unistd.h>
48#include "un-namespace.h"
49
50int
51lockf(filedes, function, size)
52	int filedes;
53	int function;
54	off_t size;
55{
56	struct flock fl;
57	int cmd;
58
59	fl.l_start = 0;
60	fl.l_len = size;
61	fl.l_whence = SEEK_CUR;
62
63	switch (function) {
64	case F_ULOCK:
65		cmd = F_SETLK;
66		fl.l_type = F_UNLCK;
67		break;
68	case F_LOCK:
69		cmd = F_SETLKW;
70		fl.l_type = F_WRLCK;
71		break;
72	case F_TLOCK:
73		cmd = F_SETLK;
74		fl.l_type = F_WRLCK;
75		break;
76	case F_TEST:
77		fl.l_type = F_WRLCK;
78		if (_fcntl(filedes, F_GETLK, &fl) == -1)
79			return (-1);
80		if (fl.l_type == F_UNLCK || fl.l_pid == getpid())
81			return (0);
82		errno = EAGAIN;
83		return (-1);
84		/* NOTREACHED */
85	default:
86		errno = EINVAL;
87		return (-1);
88		/* NOTREACHED */
89	}
90
91	return (_fcntl(filedes, cmd, &fl));
92}
93