/*

 * 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 <https://www.gnu.org/licenses/>

 *

 */

#include "gnutls_int.h"

#include <string.h>

/**

 * 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.

 *

 * Since: 3.4.0

 **/

void gnutls_memset(void *data, int c, size_t size)

{

	volatile unsigned volatile_zero;

	volatile char *vdata = (volatile char*)data;

#ifdef HAVE_EXPLICIT_BZERO

	if (c == 0) {

		explicit_bzero(data, size);

		return;

	}

#endif

	volatile_zero = 0;

	/* 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

		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