If the DSO is currently loaded, this returns the filename that it was loaded
under, otherwise it returns null. So it is also useful as a test as to
whether the DSO is currently loaded. NB: This will not necessarily return
the same value as DSO_convert_filename(dso, dso.filename), because the
DSO_METHOD's load function may have tried a variety of filenames (with
and/or without the aid of the converters) before settling on the one it
actually loaded.
If the DSO is currently loaded, this returns the filename that it was loaded under, otherwise it returns null. So it is also useful as a test as to whether the DSO is currently loaded. NB: This will not necessarily return the same value as DSO_convert_filename(dso, dso.filename), because the DSO_METHOD's load function may have tried a variety of filenames (with and/or without the aid of the converters) before settling on the one it actually loaded.