Codefolge in Schutz gegen Parameter-Tricks

[jesus]

Hallo.

In der common.php von phpbb 2.0.22
ist ein Schutz gegen Parameter-Tricks

if (@ini_get('register_globals') == '1' || strtolower(@ini_get('register_globals')) == 'on')
{
	// PHP4+ path
	$not_unset = array('HTTP_GET_VARS', 'HTTP_POST_VARS', 'HTTP_COOKIE_VARS', 'HTTP_SERVER_VARS', 'HTTP_SESSION_VARS', 'HTTP_ENV_VARS', 'HTTP_POST_FILES', 'phpEx', 'phpbb_root_path');

	// Not only will array_merge give a warning if a parameter
	// is not an array, it will actually fail. So we check if
	// HTTP_SESSION_VARS has been initialised.
	if (!isset($HTTP_SESSION_VARS) || !is_array($HTTP_SESSION_VARS))
	{
		$HTTP_SESSION_VARS = array();
	}

	// Merge all into one extremely huge array; unset
	// this later
	$input = array_merge($HTTP_GET_VARS, $HTTP_POST_VARS, $HTTP_COOKIE_VARS, $HTTP_SERVER_VARS, $HTTP_SESSION_VARS, $HTTP_ENV_VARS, $HTTP_POST_FILES);

	unset($input['input']);
	unset($input['not_unset']);

	while (list($var,) = @each($input))
	{
		if (in_array($var, $not_unset))
		{
			die('Hacking attempt!');
		}
		unset($$var);
	}

	unset($input);
}

Was ich mich frage ist, wozu ein $input['input'] und $input['not_unset']
entfernt wird und welche überhaupt?