xref: /freebsd/lib/libc/uuid/uuid_compare.c (revision f856af0466c076beef4ea9b15d088e1119a945b8)
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 <string.h>
31 #include <uuid.h>
32 
33 /*
34  * uuid_compare() - compare two UUIDs.
35  * See also:
36  *	http://www.opengroup.org/onlinepubs/009629399/uuid_compare.htm
37  *
38  * NOTE: Either UUID can be NULL, meaning a nil UUID. nil UUIDs are smaller
39  *	 than any non-nil UUID.
40  */
41 int32_t
42 uuid_compare(const uuid_t *a, const uuid_t *b, uint32_t *status)
43 {
44 	int	res;
45 	int64_t res64;
46 
47 	if (status != NULL)
48 		*status = uuid_s_ok;
49 
50 	/* Deal with NULL or equal pointers. */
51 	if (a == b)
52 		return (0);
53 	if (a == NULL)
54 		return ((uuid_is_nil(b, NULL)) ? 0 : -1);
55 	if (b == NULL)
56 		return ((uuid_is_nil(a, NULL)) ? 0 : 1);
57 
58 	/*
59 	 * We have to compare the hard way.
60 	 *
61 	 * Note that time_low is defined as unsigned 32-bit
62 	 * integer, therefore, with a significantly large
63 	 * a->time_low and a small b->time_low, we will end
64 	 * up with a value which is larger than 0x7fffffff
65 	 * which is negative if casted to signed 32-bit
66 	 * integer.
67 	 */
68 	res64 = (int64_t)a->time_low - (int64_t)b->time_low;
69 	if (res64)
70 		return ((res64 < 0) ? -1 : 1);
71 	res = (int)a->time_mid - (int)b->time_mid;
72 	if (res)
73 		return ((res < 0) ? -1 : 1);
74 	res = (int)a->time_hi_and_version - (int)b->time_hi_and_version;
75 	if (res)
76 		return ((res < 0) ? -1 : 1);
77 	res = (int)a->clock_seq_hi_and_reserved -
78 	    (int)b->clock_seq_hi_and_reserved;
79 	if (res)
80 		return ((res < 0) ? -1 : 1);
81 	res = (int)a->clock_seq_low - (int)b->clock_seq_low;
82 	if (res)
83 		return ((res < 0) ? -1 : 1);
84 	res = memcmp(a->node, b->node, sizeof(a->node));
85 	if (res)
86 		return ((res < 0) ? -1 : 1);
87 	return (0);
88 }
89