p7zip-plugins and rar extraction.

Chris Adams cmadams at hiwaay.net
Tue Apr 16 20:47:34 UTC 2013


Once upon a time, Kevin Martin <ktmdms at gmail.com> said:
> What is the reason that rar archive extraction support is not included in the 7z.so in the p7zip-plugins rpm?

In the p7zip SRPM SPEC file:

   # RAR sources removed since their license is incompatible with the LGPL

In a package review attempt for "unrar":

https://bugzilla.redhat.com/show_bug.cgi?id=319831#c25
************************************************************************
I spoke via email to Eugene Roshal about this issue. He was unaware that clamav
had used derived code from their implementation in clamav, under the GPL
license, and stated that he did not grant them permission to do so.

He said that the only way he was willing for such code to be used was with a
clause like the following:

"The unRAR sources cannot be used to re-create the RAR compression algorithm, 
 which is proprietary. Distribution of modified unRAR sources in separate form 
 or as a part of other software is permitted, provided that it is clearly
 stated in the documentation and source comments that the code may
 not be used to develop a RAR (WinRAR) compatible archiver."

Unfortunately, such a restriction conflicts directly with the GPL, and is a
showstopper.

This code cannot go into Fedora as is. All RAR v3.x support would need to be
stripped out, before it could be considered. Given that most RAR files are RAR
v3, that severely limits the usefulness of this application.
************************************************************************

Basically, the only documentation of the file format is in the unrar
source code, and it is under a non-free license.  I don't think anyone
has tried to reverse engineer it to make a clean-room implementation.
-- 
Chris Adams <cmadams at hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.


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