usr/src/boot/lib/libc/uuid/uuid_is_nil.c

   1 /*-
   2  * Copyright (c) 2002,2005 Marcel Moolenaar
   3  * Copyright (c) 2002 Hiten Mahesh Pandya
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  *
  27  * $FreeBSD$
  28  */
  29
  30 #include <uuid.h>
  31
  32 /*
  33  * uuid_is_nil() - return whether the UUID is a nil UUID.
  34  * See also:
  35  *      http://www.opengroup.org/onlinepubs/009629399/uuid_is_nil.htm
  36  */
  37 int32_t
  38 uuid_is_nil(const uuid_t *u, uint32_t *status)
  39 {
  40         const uint32_t *p;
  41
  42         if (status)
  43                 *status = uuid_s_ok;
  44
  45         if (!u)
  46                 return (1);
  47
  48         /*
  49          * Pick the largest type that has equivalent alignment constraints
  50          * as an UUID and use it to test if the UUID consists of all zeroes.
  51          */
  52         p = (const uint32_t*)u;
  53         return ((p[0] == 0 && p[1] == 0 && p[2] == 0 && p[3] == 0) ? 1 : 0);
  54 }