1 /* $NetBSD: flock.c,v 1.6 2008/04/28 20:24:12 martin Exp $ */
2
3 /*-
4 * Copyright (c) 2001 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Todd Vierling.
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 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 /*
33 * Emulate flock() with fcntl(), where available.
34 * Otherwise, don't do locking; just pretend success.
35 */
36
37 #include "nbtool_config.h"
38
39 #if !HAVE_FLOCK
40 #include <errno.h>
41 #include <fcntl.h>
42
flock(int fd,int op)43 int flock(int fd, int op) {
44 int rc = 0;
45
46 #if defined(F_SETLK) && defined(F_SETLKW)
47 struct flock fl = {0};
48
49 switch (op & (LOCK_EX|LOCK_SH|LOCK_UN)) {
50 case LOCK_EX:
51 fl.l_type = F_WRLCK;
52 break;
53
54 case LOCK_SH:
55 fl.l_type = F_RDLCK;
56 break;
57
58 case LOCK_UN:
59 fl.l_type = F_UNLCK;
60 break;
61
62 default:
63 errno = EINVAL;
64 return -1;
65 }
66
67 fl.l_whence = SEEK_SET;
68 rc = fcntl(fd, op & LOCK_NB ? F_SETLK : F_SETLKW, &fl);
69
70 if (rc && (errno == EAGAIN))
71 errno = EWOULDBLOCK;
72 #endif
73
74 return rc;
75 }
76 #endif
77