_vboot_reference/firmware/lib/utility.c

/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 *
 * Utility functions that need to be built as part of the firmware.
 */

#include "sysincludes.h"

#include "utility.h"

int SafeMemcmp(const void *s1, const void *s2, size_t n) {
	const unsigned char *us1 = s1;
	const unsigned char *us2 = s2;
	int result = 0;

	if (0 == n)
		return 0;

	/*
	 * Code snippet without data-dependent branch due to Nate Lawson
	 * (nate@root.org) of Root Labs.
	 */
	while (n--)
		result |= *us1++ ^ *us2++;

	return result != 0;
}