[cups-devel] CUPS License Change Coming

[Didier 'OdyX' Raboud]

Le jeudi, 30 novembre 2017, 13.42:41 h CET Zdenek Dohnal a écrit :
> So as you wrote several emails before, software under GPLv2 only can
> dynamically link CUPS library, because CUPS library can be marked as
> OS-supplied library - which makes software+licenses compatible, if
> upstream holder of SW, which wants to dynamically link CUPS, see it as
> compatible as well.

Considering libraries as OS-supplied is not necessarily something the library 
consumers can decide on their end. In the case of Debian, for instance, we 
have long refused (and still refuse) to consider the OpenSSL library an "OS-
supplied" library. This has pushed tons of GPLv2 software authors to adopt the 
"GPLv2(+) with OpenSSL Exception" which contains the following:

> In addition, as a special exception, the author of this
> program gives permission to link the code of its
> release with the OpenSSL project's "OpenSSL" library (or
> with modified versions of it that use the same license as
> the "OpenSSL" library), and distribute the linked
> executables. You must obey the GNU General Public
> License in all respects for all of the code used other
> than "OpenSSL".  (…)

> Can we agree on exact sentence, which should be added to
> copyright/license file of software under GPLv2 only license and wants to
> link against CUPS library? Something like:
> 
> "This software is permitted to link against CUPS library, because CUPS
> is considered as OS-supplied library and therefore it falls under Apache
> Software License 2.0 exception."

I'm not a Debian FTP Master, but I very much doubt such a formulation would be 
deemed acceptable for Debian. "CUPS is considered as OS-supplied library" is 
clearly over-reaching. Debian doesn't consider (and will not consider) CUPS as 
OS-supplied library.

The problem is still that such a license change for CUPS forces GPL2-only 
upstream authors (such as gutenprint) who used to link against CUPS to 
relicence to a compatible license (GPL-2+ or GPL-2 with a CUPS-specific 
exception). And that's far from easy: it's de facto only possible iff all 
present and past copyright holder unanimously agree, or have waived their 
rights to an organisation registered as sole copyright holder (or such).

tl:dr; For Debian, CUPS' license change will imply that no GPL-2-only software 
will be allowed to dynamically link against it.

Cheers,
    OdyX