Re: UNIX Compressed Files From A PC

[Ted Dennison <dennison@telepath.com>]

In article <3995C90A.E72C055F@acm.org>,
  "Marin D. Condic" <mcondic-nospam@acm.org> wrote:
> I'm looking for a package that can access UNIX compressed files and
> unpack them for me. I'm in a situation where I've got to read these
> files from a WinNT PC and the files will be resident either on the PC
> or across the net on a Sun platform. I want to access them as any
> other byte stream file - Open/Read/Write/Seek/Close operations are
> what I need. Does anybody know of an Ada package that is generally
> available that can do this?

One issue that you should be aware of that I haven't seen mentioned: The
Sun Unix "compress" utility uses several *patented* LZW algorithms. That
is why you won't see any free utilities to perform LZW compression. If
you write such a routine yourself, *you* will be infringing on the
patents unless you or your customer makes some kind of arrangement with
the patent holders.

Apparently the patents do not prohibit uncompression, but I suspect
you'll have a hard time finding free solutions that just do
uncompression when there are better non-patented algorithms available
out there.

From what I've heard, it may be the case that you can write a utility to
just read the data from a compressed archive without violating the
patent. But If you will have a need to perform compression yourself, you
should make sure that your employers get permission to use the patented
algorithms before you write so much as a line of infringing code. If
they want to slide the issue under the rug, get their legal department
involved yourself. Once the true pain of using "compress" is made clear
to them, they ought to be much more amenable to alternative free
solutions.

For the FSF's take on this, see
http://www.gnu.org/bulletins/bull14.html#SEC13


--
T.E.D.

http://www.telepath.com/~dennison/Ted/TED.html


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