rem: b = (void *)b_elems + (a_elems - (char *)a);
add: b = (void *)b_elems + ((char *)a-a_elems);
context: match_different(const struct ipt_entry_match *a,		const char *a_elems,		const char *b_elems){	const struct ipt_entry_match *b;	/* Offset of b is the same as a. */	b = (void *)b_elems + (a_elems - (char *)a);	if (a->match_size != b->match_size)		return 1;	if (strcmp(a->u.name, b->u.name) != 0)		return 1;	/* FIXME: If kernel modifies these (eg. RATE), then we'll           never match --RR */	if (memcmp(a->data, b->data, a->match_size - sizeof(*a)) != 0)		return 1;	return 0;}