lockf.c revision 331722 
1/*	$NetBSD: lockf.c,v 1.3 2008/04/28 20:22:59 martin Exp $	*/
2/*-
3 * Copyright (c) 1997 The NetBSD Foundation, Inc.
4 * All rights reserved.
5 *
6 * This code is derived from software contributed to The NetBSD Foundation
7 * by Klaus Klein.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
20 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
22 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD: stable/11/lib/libc/gen/lockf.c 331722 2018-03-29 02:50:57Z eadler $");
33
34#include "namespace.h"
35#include <errno.h>
36#include <fcntl.h>
37#include <unistd.h>
38#include "un-namespace.h"
39#include "libc_private.h"
40
41int
42lockf(int filedes, int function, off_t size)
43{
44	struct flock fl;
45	int cmd;
46
47	fl.l_start = 0;
48	fl.l_len = size;
49	fl.l_whence = SEEK_CUR;
50
51	switch (function) {
52	case F_ULOCK:
53		cmd = F_SETLK;
54		fl.l_type = F_UNLCK;
55		break;
56	case F_LOCK:
57		cmd = F_SETLKW;
58		fl.l_type = F_WRLCK;
59		break;
60	case F_TLOCK:
61		cmd = F_SETLK;
62		fl.l_type = F_WRLCK;
63		break;
64	case F_TEST:
65		fl.l_type = F_WRLCK;
66		if (((int (*)(int, int, ...))
67		    __libc_interposing[INTERPOS_fcntl])(filedes, F_GETLK, &fl)
68		    == -1)
69			return (-1);
70		if (fl.l_type == F_UNLCK || (fl.l_sysid == 0 &&
71		    fl.l_pid == getpid()))
72			return (0);
73		errno = EAGAIN;
74		return (-1);
75		/* NOTREACHED */
76	default:
77		errno = EINVAL;
78		return (-1);
79		/* NOTREACHED */
80	}
81
82	return (((int (*)(int, int, ...))
83	    __libc_interposing[INTERPOS_fcntl])(filedes, cmd, &fl));
84}
85