directory refresh in shared network drive

I have written a program that checks the contents of a directory, does some
stuff with the files, sleeps three minutes, and does it again. The directory
is on a windows share.

By checking with opendir/readdir/closedir, I always get the same results,
even after the directory contents have changed.

I switched to using `dir /b` and now get a current listing. This works,
after chomping the results, but I don't think I should have to do that.

Please advise?