1 /* $NetBSD: __cmsg_alignbytes.c,v 1.1 2012/01/20 14:08:05 joerg Exp $ */
2
3 /*-
4 * Copyright (c) 2000 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jun-ichiro Hagino.
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 #include <sys/cdefs.h>
33 __RCSID("$NetBSD: __cmsg_alignbytes.c,v 1.1 2012/01/20 14:08:05 joerg Exp $");
34
35 #include "namespace.h"
36 #include <sys/types.h>
37 #include <sys/param.h>
38 #include <sys/sysctl.h>
39 #include <sys/socket.h>
40
41 int __cmsg_alignbytes(void);
42
43 int
__cmsg_alignbytes(void)44 __cmsg_alignbytes(void)
45 {
46 static int alignbytes = -1;
47 #ifdef HW_ALIGNBYTES
48 int mib[2];
49 size_t len;
50 int ret;
51 #endif
52
53 if (alignbytes > 0)
54 return alignbytes;
55
56 #ifdef HW_ALIGNBYTES
57 mib[0] = CTL_HW;
58 mib[1] = HW_ALIGNBYTES;
59 len = sizeof(alignbytes);
60 ret = sysctl(mib, (u_int) (sizeof(mib) / sizeof(mib[0])),
61 (void *)&alignbytes, &len, NULL, (size_t)0);
62 if (ret >= 0 && alignbytes >= 0)
63 return alignbytes;
64 #endif
65 /* last resort */
66 alignbytes = ALIGNBYTES;
67 return alignbytes;
68 }
69