Holy frick, no one here can give you an answer!
AS THE MANUAL STATES, it depends on the setup of your webserver and of PHP ( php.ini )
Find out if safe_mode is on or off and if its on, find out what settings are being used with it, then you can go read the manual and see how it will affect you / this function call.
Certain functions in PHP can be disabled completely with safe_mode, but theres no way for anyone on this board to tell you which ones are enabled / disabled on your webserver.
So the answer is, it depends. Go get some docs, talk to your sysadmin, and read the manual again.