PHP streams and stat/stat_url function

with a PHP Stream, when are the stat functions called?? the php_stream_wrapper_ops structure's stat and stat_url members and php_stream_ops structure's stat member. Right now I have a php wrapper that wraps around the PhysFS libraru (http://www.icculus.org/physfs/) And I would like to be able to implement stat functions so in my PHP code I can check whether a file exists or if it's a directory.. This wrapper is registered as physfs:// AND overrides the php_plain_files wrapper so I can use regular paths and they will ALL be forced to access the physfs system.. (I un-static'ed the structure in main/streams.c so I could "illegally" override the members with my module. . It's for use in an embedded game scripting engine..soo.) right now I have enough implemented so opening files,directories, includes and requires all go through the physfs wrapper. Just is_dir, is_file, etc.. don't go through the wrapper and I would like to figure out how to make them... Also, what is the cast member of the stream_ops for?? Edward Rudd