The zzip library was originally developed by Tomi Ollila as a
set of zip decoder routines. Guido Draheim did pick it up and
wrapped them under a call synopsis matching their posix
api calls. Therefore zzip_open() has the same
synopsis as open(2) but it can open zipped files.
Later the distinction was made between magic wrappers and apis
for direct access to zip archives and the files contained
in the archive.
These (three) functional apis have little helper functions alongside including those to get the posix filehandle out of a zzip handle and to get some attributes about the data handle represented by a zzip handle. Plus checking for error codes that may have been generated from internal checks.