> I am not sure to understand. Do you mean the whole PATH environment
> variable? I doubt that it is passed to _getfullpathname.
> Or do you have very long paths for one directory? the TEMP environment
> variable, for example? I'd be curious to see its value.

I don't have it offhand, but it was the whole PATH environment variable, complete with semicolons. That's probably the *real* bug. Whatever was passing that into abspath didn't seem to mind getting back an empty string (although that may have been further processed in the function, I didn't follow past the call to _getfullpathname).

> And one decision problem... What should we do when too long str is
> passed to ntpath._getfullpathname? Report overflow error? Or convert to
> unicode and retry with GetFullPathNameW? Hmm....

abspath should be able to be called with str or unicode of arbitrary lengths. Consumers of it shouldn't have to be concerned with the platform implementation when it can be smoothed over by the module. Whether this is done in abspath or _getfullpathname probably isn't too important, since end-users generally shouldn't be calling _getfullpathname, directly.