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/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
/*! \file */
#include <config.h>
#include <isc/safe.h>
#include <string.h>
#include <isc/util.h>
#ifdef _MSC_VER
#pragma optimize("", off)
#endif
isc_boolean_t
isc_safe_memequal(const void *s1, const void *s2, size_t n) {
uint8_t acc = 0;
if (n != 0U) {
const uint8_t *p1 = s1, *p2 = s2;
do {
acc |= *p1++ ^ *p2++;
} while (--n != 0U);
}
return (ISC_TF(acc == 0));
}
int
isc_safe_memcompare(const void *b1, const void *b2, size_t len) {
const unsigned char *p1 = b1, *p2 = b2;
size_t i;
int res = 0, done = 0;
for (i = 0; i < len; i++) {
/* lt is -1 if p1[i] < p2[i]; else 0. */
int lt = (p1[i] - p2[i]) >> CHAR_BIT;
/* gt is -1 if p1[i] > p2[i]; else 0. */
int gt = (p2[i] - p1[i]) >> CHAR_BIT;
/* cmp is 1 if p1[i] > p2[i]; -1 if p1[i] < p2[i]; else 0. */
int cmp = lt - gt;
/* set res = cmp if !done. */
res |= cmp & ~done;
/* set done if p1[i] != p2[i]. */
done |= lt | gt;
}
return (res);
}
void
isc_safe_memwipe(void *ptr, size_t len) {
if (ISC_UNLIKELY(ptr == NULL || len == 0))
return;
#if HAVE_EXPLICIT_BZERO
explicit_bzero(ptr, len);
#else
memset(ptr, 0, len);
#endif
}
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