Function pop_stack_entry

freebsd/netinet/in_fib_algo.c:276–308

* * Example: * stack: 10.0.1.0/24,nh=3 array: 10.0.1.0/25,nh=4 -> ++10.0.1.128/24,nh=3 * * */

 *
 */
static bool
pop_stack_entry(struct bsearch4_array *dst_array, struct bsearch4_array *stack)
{
	uint32_t last_stack_addr, last_array_addr;

	struct bsearch4_record *br_prev = get_last_entry(dst_array);
	struct bsearch4_record *pstack = get_last_entry(stack);

	/* Regardless of the result, pop stack entry */
	stack->num_items--;

	/* Prefix last address for the last entry in lookup array */
	last_array_addr = (br_prev->addr4 | ~br_prev->mask4);
	/* Prefix last address for the stack record entry */
	last_stack_addr = (pstack->addr4 | ~pstack->mask4);

	if (last_stack_addr > last_array_addr) {
		/*
		 * Stack record covers > address space than
		 * the last entry in the lookup array.
		 * Add the remaining parts of a stack record to
		 * the lookup array.
		 */
		struct bsearch4_record br_new = {
			.addr4 = last_array_addr + 1,
			.mask4 = pstack->mask4,
			.nh = pstack->nh,
		};
		return (add_array_entry(dst_array, &br_new));
	}

	return (true);
}

/*
 * Updates resulting array @dst_array with a rib entry @rib_entry.