lib/libc/compat/net/__cmsg_alignbytes.c

   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
  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 }