<?php
$can_set = true;
if (!function_exists('set_time_limit'))
$can_set = false;
// Are we able to use the function
$current_time_limit = ini_get('max_execution_time');
@set_time_limit(123);
$new_time_limit = ini_get('max_execution_time');
@set_time_limit($current_time_limit);
if (empty($current_time_limit) || $current_time_limit === $new_time_limit)
$can_set = false;
echo $can_set;