lib/libc/uuid/uuid_compare.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: src/lib/libc/uuid/uuid_compare.c,v 1.6 2007/04/05 02:07:33 delphij Exp $
  28  * $DragonFly: src/lib/libc/uuid/uuid_compare.c,v 1.1 2007/06/16 19:57:14 dillon Exp $
  29  */
  30
  31 #include <string.h>
  32 #include <uuid.h>
  33
  34 /* A macro used to improve the readability of uuid_compare(). */
  35 #define DIFF_RETURN(a, b, field)        do {                    \
  36         if ((a)->field != (b)->field)                           \
  37                 return (((a)->field < (b)->field) ? -1 : 1);    \
  38 } while (0)
  39
  40 /*
  41  * uuid_compare() - compare two UUIDs.
  42  * See also:
  43  *      http://www.opengroup.org/onlinepubs/009629399/uuid_compare.htm
  44  *
  45  * NOTE: Either UUID can be NULL, meaning a nil UUID. nil UUIDs are smaller
  46  *       than any non-nil UUID.
  47  */
  48 int32_t
  49 uuid_compare(const uuid_t *a, const uuid_t *b, uint32_t *status)
  50 {
  51         int     res;
  52
  53         if (status != NULL)
  54                 *status = uuid_s_ok;
  55
  56         /* Deal with NULL or equal pointers. */
  57         if (a == b)
  58                 return (0);
  59         if (a == NULL)
  60                 return ((uuid_is_nil(b, NULL)) ? 0 : -1);
  61         if (b == NULL)
  62                 return ((uuid_is_nil(a, NULL)) ? 0 : 1);
  63
  64         /* We have to compare the hard way. */
  65         DIFF_RETURN(a, b, time_low);
  66         DIFF_RETURN(a, b, time_mid);
  67         DIFF_RETURN(a, b, time_hi_and_version);
  68         DIFF_RETURN(a, b, clock_seq_hi_and_reserved);
  69         DIFF_RETURN(a, b, clock_seq_low);
  70
  71         res = memcmp(a->node, b->node, sizeof(a->node));
  72         if (res)
  73                 return ((res < 0) ? -1 : 1);
  74         return (0);
  75 }
  76
  77 #undef DIFF_RETURN