As an aside, another thing that you have to really watch-out for is that many operating systems do not handle having many directory searches going on at the same time.   I remember first encountering this years ago in Windows, and encountering it over and over since then.   You just can’t have too many nested, or simultaneous directory walk-thrus going on at the same time, and (Windows’) behavior in that context is sometimes not to throw an error-message ... it just does the wrong thing.   Caveat coder.   The workaround is to stash the file-and-directory names and to do a series of lookups one after the other.