Description:
------------
//x.php located in /
$is=file_exists("y.php"/*located in / too*/);
//y.php located in /dir/
echo $is;

it shows 0 . all file addresses should be ralated to their first parent . so the file_exists even if called in y.php in /dir/ should see that it`s included from / and search it there .

and another problem listed in code section .

Reproduce code:
---------------
<?
$x="xxxxxxxxxx";
function y()
{
 echo $x;
}

y();

//shows nothing
?>

Expected result:
----------------
xxxxxxxxxx