MyBB Community Forums

At first time, I hook my function at index_start (in this function I call get_unviewable_forums()), it works fine (get_unviewable_forums() return a list of unviewable forums' id), but if I call it at index_end, it return null instead of list of unviewable forums' id.

The get_unviewable_forums() function fails at the end of index.php because of this line:

$permissioncache['-1'] = "1";

You could call it at the beginning of index.php, which will force the permission cache to be built, then call the function at the end of index.php to your liking.