xref: /freebsd/contrib/unbound/compat/memmove.c (revision 98e0ffaefb0f241cda3a72395d3be04192ae0d47)

/*
 *	memmove.c: memmove compat implementation.
 *
 *	Copyright (c) 2001-2006, NLnet Labs. All rights reserved.
 *
 * See LICENSE for the license.
*/

#include <config.h>
#include <stdlib.h>

void *memmove(void *dest, const void *src, size_t n);

void *memmove(void *dest, const void *src, size_t n)
{
	uint8_t* from = (uint8_t*) src;
	uint8_t* to = (uint8_t*) dest;

	if (from == to || n == 0)
		return dest;
	if (to > from && to-from < (int)n) {
		/* to overlaps with from */
		/*  <from......>         */
		/*         <to........>  */
		/* copy in reverse, to avoid overwriting from */
		int i;
		for(i=n-1; i>=0; i--)
			to[i] = from[i];
		return dest;
	}
	if (from > to && from-to < (int)n) {
		/* to overlaps with from */
		/*        <from......>   */
		/*  <to........>         */
		/* copy forwards, to avoid overwriting from */
		size_t i;
		for(i=0; i<n; i++)
			to[i] = from[i];
		return dest;
	}
	memcpy(dest, src, n);
	return dest;
}