lockf.c revision 90039 
1/*-
2 * Copyright (c) 1997 The NetBSD Foundation, Inc.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to The NetBSD Foundation
6 * by Klaus Klein.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *        This product includes software developed by the NetBSD
19 *        Foundation, Inc. and its contributors.
20 * 4. Neither the name of The NetBSD Foundation nor the names of its
21 *    contributors may be used to endorse or promote products derived
22 *    from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
25 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
26 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
27 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
28 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
29 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
30 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
31 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
32 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
33 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
34 * POSSIBILITY OF SUCH DAMAGE.
35 */
36
37/*	$NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $	*/
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: head/lib/libc/gen/lockf.c 90039 2002-02-01 00:57:29Z obrien $");
40
41#include "namespace.h"
42#include <errno.h>
43#include <fcntl.h>
44#include <unistd.h>
45#include "un-namespace.h"
46
47int
48lockf(filedes, function, size)
49	int filedes;
50	int function;
51	off_t size;
52{
53	struct flock fl;
54	int cmd;
55
56	fl.l_start = 0;
57	fl.l_len = size;
58	fl.l_whence = SEEK_CUR;
59
60	switch (function) {
61	case F_ULOCK:
62		cmd = F_SETLK;
63		fl.l_type = F_UNLCK;
64		break;
65	case F_LOCK:
66		cmd = F_SETLKW;
67		fl.l_type = F_WRLCK;
68		break;
69	case F_TLOCK:
70		cmd = F_SETLK;
71		fl.l_type = F_WRLCK;
72		break;
73	case F_TEST:
74		fl.l_type = F_WRLCK;
75		if (_fcntl(filedes, F_GETLK, &fl) == -1)
76			return (-1);
77		if (fl.l_type == F_UNLCK || fl.l_pid == getpid())
78			return (0);
79		errno = EAGAIN;
80		return (-1);
81		/* NOTREACHED */
82	default:
83		errno = EINVAL;
84		return (-1);
85		/* NOTREACHED */
86	}
87
88	return (_fcntl(filedes, cmd, &fl));
89}
90