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/*
* Copyright (C) 2014 Red Hat
*
* This file is part of GnuTLS.
*
* The GnuTLS is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
*/
#ifdef TEST_SAFE_MEMSET
# include <string.h>
#else
# include <gnutls_int.h>
#endif
/**
* gnutls_memset:
* @data: the memory to set
* @c: the constant byte to fill the memory with
* @size: the size of memory
*
* This function will operate similarly to memset(), but will
* not be optimized out by the compiler.
*
* Returns: void.
*
* Since: 3.4.0
**/
void gnutls_memset(void *data, int c, size_t size)
{
volatile unsigned volatile_zero = 0;
volatile char *vdata = (volatile char*)data;
/* This is based on a nice trick for safe memset,
* sent by David Jacobson in the openssl-dev mailing list.
*/
if (size > 0) {
do {
memset(data, c, size);
} while(vdata[volatile_zero] != c);
}
}
/**
* gnutls_memcmp:
* @s1: the first address to compare
* @s2: the second address to compare
* @n: the size of memory to compare
*
* This function will operate similarly to memcmp(), but will operate
* on time that depends only on the size of the string. That is will
* not return early if the strings don't match on the first byte.
*
* Returns: non zero on difference and zero if the buffers are identical.
*
* Since: 3.4.0
**/
int gnutls_memcmp(const void *s1, const void *s2, size_t n)
{
unsigned i;
unsigned status = 0;
const uint8_t *_s1 = s1;
const uint8_t *_s2 = s2;
for (i=0;i<n;i++) {
status |= (_s1[i] ^ _s2[i]);
}
return status;
}
#ifdef TEST_SAFE_MEMSET
int main()
{
char x[64];
gnutls_memset(x, 0, sizeof(x));
return 0;
}
#endif
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