Clément Lassieur <clement@lassieur.org> writes:

>>> Like you say, the authors have taken GPL code from another project
>>> and incorporated
>>> it into unrar - that is only possible if the the resultant work is
>>> GPL compatible.
>>
>> Or if the resultant work is illegal?
>
> Actually, unrarlib is dual-licensed, so it is possible to use it within
> a proprietary program (see http://www.unrarlib.org/license.html).
>
> But I'll trust you that COPYING is enough :)  Sorry for bothering you
> then.
>
> Clément

I think Debian considered it to be non-free, see the package page[0] and
the copyright page[1].

However, 'unar'[2] can also extract rar files and is free
software[3]. It is on my TODO list. (But I am busy studying right now
and the program uses gnustep which is something I am not familiar with.)
John, if you like you can look into it.

[0]: https://packages.debian.org/sid/unrar
[1]: http://metadata.ftp-master.debian.org/changelogs/non-free/u/unrar-nonfree/unrar-nonfree_5.4.5-1_copyright
[2]: https://packages.debian.org/sid/unar
[3]: http://metadata.ftp-master.debian.org/changelogs/main/u/unar/unar_1.10.1-1_copyright