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