[DebianGIS-dev] Bug#422537: cfitsio3: GPL/PD but includes GPL compress.c from gzip

[Justin Pryzby]

Package: libcfitsio2, libcfitsio3, slang-cfitsio, libgdal1-1.3.2
# apt-cache rdepends output
# kst-plugins is gpl
# fv is written by the same guy as fitsio so..

It's unclear to me why/that/if it's allowed for cfitsio to include GPL
compress.c from gzip, when it is not itself GPL.  In particular, it
isn't clear why it's allowed for packages which depend on fitsio to be
distributed under a license other than GPL (modulo exceptions from the
zlib people).

The documented GNU interpretation is that dynamic linking to GPL
software is allowed only by GPL software.

Naturally, copyright holders of library packages can make an exception
to this ("As a special exception to the terms of the GPL, one is allowed
to link software distributed under any license to this library.").

Debian has taken the conservative stance that, unless otherwise noted,
authors of GPL libraries should be assumed to take the GNU
interpretation for distribution of their own project, and Debian should
either: Request such an exception to the GPL (not specific to Debian);
or, Avoid linking non-GPL packages to that GPL library.