1/*	$NetBSD: lockf.c,v 1.3 2008/04/28 20:22:59 martin Exp $	*/
2/*-
3 * SPDX-License-Identifier: BSD-2-Clause
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 "namespace.h"
34#include <errno.h>
35#include <fcntl.h>
36#include <unistd.h>
37#include "un-namespace.h"
38#include "libc_private.h"
39
40int
41lockf(int filedes, int function, off_t size)
42{
43	struct flock fl;
44	int cmd;
45
46	fl.l_start = 0;
47	fl.l_len = size;
48	fl.l_whence = SEEK_CUR;
49
50	switch (function) {
51	case F_ULOCK:
52		cmd = F_SETLK;
53		fl.l_type = F_UNLCK;
54		break;
55	case F_LOCK:
56		cmd = F_SETLKW;
57		fl.l_type = F_WRLCK;
58		break;
59	case F_TLOCK:
60		cmd = F_SETLK;
61		fl.l_type = F_WRLCK;
62		break;
63	case F_TEST:
64		fl.l_type = F_WRLCK;
65		if (((int (*)(int, int, ...))
66		    *(__libc_interposing_slot(INTERPOS_fcntl)))
67		    (filedes, F_GETLK, &fl) == -1)
68			return (-1);
69		if (fl.l_type == F_UNLCK || (fl.l_sysid == 0 &&
70		    fl.l_pid == getpid()))
71			return (0);
72		errno = EAGAIN;
73		return (-1);
74		/* NOTREACHED */
75	default:
76		errno = EINVAL;
77		return (-1);
78		/* NOTREACHED */
79	}
80
81	return (INTERPOS_SYS(fcntl, filedes, cmd, (intptr_t)&fl));
82}
83