I have an unusual situation where I need multiple users to be able to upload and execute PHP code on my Apache server, but I cannot allow one user to access another user's PHP source (if concrete examples make you feel better, imagine I'm hosting a PHP programming competition).
Here's what I have so far in the PHP.ini:
disable_functions = readfile, fpassthru, file, file_get_contents, system, fopen, symlink, rename, copy, exec, passthru, pcntl_exec, backtick_operator, shell_exec, popen, proc_open
What other functions would I need to add to this list, to prevent PHP code from accessing local files (and hence other PHP source?)?