[Zlib-devel] Re: deflate 64

[Greg Roelofs]

> And if zLib itself don't support deflate64, the only option is switch to
> unzip 5.5 source, which is bigger than zLib and, in my opinion less easy to
> use. A final user (and me) have not knowledge to modify the core inflate
> engine.

zlib doesn't support shrinking or imploding, either.  Both are required for
full zipfile support.

> - and, do you remember the PKWare problem with ARC 15 year ago ?
> PKWare made a ARC compatible software (PKARC). ARC was not open format. The
> ARC maker company win a trial againt PKWare. So PKWare made a new format,
> Zip, and decided publish full specification in a public file appnotes.txt.
> After Infozip started working with this appnotes.txt

That touches on many of the facts but leaves out almost as many.  The
fact that ARC wasn't open was not the issue in the trial; the problem
was that "ARC" was a trademark, and "PKARC" violated it.  Katz released
PKPAK after losing the case--it was identical to PKARC except in name
and the use of a .PAK extension instead of .ARC.  And between PKWARE's
new format and Info-ZIP was Samuel H. Smith, who wrote the first open-
source decoder, I believe.  UnZip was originally based on that, and
Info-ZIP formed around it.  Then came Zip.

Anyway, the fact that there were and are closed formats was not relevant
to the legalities of anything that happened so far, only to the ease or
difficulty of implementation.

> Unfortunatelly, Phil Katz had died. And the quality of new specification in
> appnotes is not good. I've read the new encryption documentation is not
> complete...

The quality was never good.  Mark and Jean-loup found and fixed numerous
errors in the original deflate description, too.

Greg