"It is better to change the file permissions with chmod() after creating the file."
If you take that advice seriously, consider setting your umask so that files are created private to your user, then use chmod to open them up.
<?php
umask(0077);
chmod('/path/to/file', 0644);
?>
Whenever reasonable, default to shut and open as needed (like above) instead of default to open and shut as needed. The above still has a race condition, but the race condition will deny appropriate access instead of granting inappropriate access.
