1 /*
2 * cc_cmp_safe.c
3 * corecrypto
4 *
5 * Created on 04/22/2014
6 *
7 * Copyright (c) 2014,2015 Apple Inc. All rights reserved.
8 *
9 *
10 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
11 *
12 * This file contains Original Code and/or Modifications of Original Code
13 * as defined in and that are subject to the Apple Public Source License
14 * Version 2.0 (the 'License'). You may not use this file except in
15 * compliance with the License. The rights granted to you under the License
16 * may not be used to create, or enable the creation or redistribution of,
17 * unlawful or unlicensed copies of an Apple operating system, or to
18 * circumvent, violate, or enable the circumvention or violation of, any
19 * terms of an Apple operating system software license agreement.
20 *
21 * Please obtain a copy of the License at
22 * http://www.opensource.apple.com/apsl/ and read it before using this file.
23 *
24 * The Original Code and all software distributed under the License are
25 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
26 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
27 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
28 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
29 * Please see the License for the specific language governing rights and
30 * limitations under the License.
31 *
32 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
33 */
34
35 #include <corecrypto/cc_priv.h>
36
37 int
cc_cmp_safe(size_t num,const void * ptr1,const void * ptr2)38 cc_cmp_safe(size_t num, const void * ptr1, const void * ptr2)
39 {
40 size_t i;
41 const uint8_t *s = (const uint8_t *)ptr1;
42 const uint8_t *t = (const uint8_t *)ptr2;
43 uint8_t flag = ((num <= 0)?1:0); // If 0 return an error
44 for (i = 0; i < num; i++) {
45 flag |= (s[i] ^ t[i]);
46 }
47 CC_HEAVISIDE_STEP(flag, flag); // flag=(flag==0)?0:1;
48 return flag; // 0 iff all bytes were equal, 1 if there is any difference
49 }
50