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Re: GPL "+" question

On 29/05/15 16:30, Ole Streicher wrote:
> Miriam Ruiz <miriam@debian.org> writes:
>> So in my opinion, if you modify a code which was released under GPL2+
>> and you license your modifications as GPL3+, the resulting work has to
>> also be GPL, and the terms or conditions that apply are those of the
>> version 3 of the lincense, or later, but you're not effectively
>> relicensing the code that is not yours, so that part would be still
>> licensed as GPL2+ by the author and copyright holder.
> I may give to others the permission to use the modified/redistributed
> file under GPL-3+. This permission is what is usually called "License".
> In that sense, the license is changed.

I think you're mixing up the license of a work, and the effective
license of a combined work.

A work is an abstract legal thing, dating back to when the most advanced
computer available was a monk with an abacus.

A file is a computing concept. The law says nothing about files. If
various people have contributed bits of a file, my understanding is that
the file is a combined work consisting of individual works by those people.

To distribute a file that contains one or more works in a way that
copyright would not normally allow without the result being illegal, you
must get permission from all the copyright holders. A copyright license
is just pre-emptive permission from a copyright holder - "if you follow
these conditions, the answer is yes" - so the most common way to get
permission from all the copyright holders is to comply with all the
conditions imposed by all the copyright holders, simultaneously. For
instance, if the file combines a GPL-2+ work with a GPL-3+ work, you
must simultaneously comply with both

     GPL-2 or GPL-3 or some future version


     GPL-3 or some future version

In this simple case, the second condition implies the first, so you
might use a shorthand: "this is effectively the same as the whole thing
being GPL-3+". However, this is just a shorthand, and the real status is
somewhat more complicated.

However, the general case is not this simple:

> http://www.opensource.apple.com/source/xnu/xnu-1456.1.26/bsd/sys/msg.h
> This is a file that is initially copyrighted by Daniel Boulet (and
> licensed under BSD-2-Clause). However, without any other change, it also
> has the header
> | Copyright (c) 2000-2007 Apple Inc. All rights reserved.
> | [...]
> | This file contains Original Code and/or Modifications of Original Code
> | as defined in and that are subject to the Apple Public Source License
> | Version 2.0 (the 'License'). You may not use this file except [...]

So what you have here is (claimed to be) a file containing a combination
of a work by Daniel Boulet, licensed under BSD-2-Clause, and a work by
Apple, licensed under APSL-2.0.

To distribute that file, assuming that the claim is true, you must
simultaneously comply with the conditions of the BSD-2-Clause license
(because if you don't, you are infringing Daniel Boulet's copyright),
and with the conditions of the APSL-2.0 (because if you don't, you are
infringing Apple's copyright).

If Apple have not, in fact, modified the file (except to add their
license boilerplate, which might not be sufficiently creative to be
considered to be a copyrightable work), then their assertion that they
hold copyright on the file might not actually be true. If that is the
case, then it might be possible (at your own legal risk) to disregard
that part, then defend yourself on that basis if they sue you. I
wouldn't want to try it myself, because Apple's lawyers are more
expensive than I can afford; and there's no real point anyway, because
you can presumably just get Daniel Boulet's original version of the file
from FreeBSD (?) and avoid the whole issue.

If the two licenses are contradictory (one says you must do something
and the other says you must not, e.g. GPL-2 and GPL-3, or GPL and
OpenSSL) then the combined work is non-distributable. I suspect these
two licenses are not contradictory, though - the BSD-2-clause license
doesn't require much.

> Would you accept such a file in Debian? It is clearly not BSD-licensed,
> even if an unchanged BSD-licensed version exists.

If we can exercise the rights demanded by the DFSG while simultaneously
complying with both the applicable licenses, then the work is Free.

I don't know the precise status of the APSL-2.0 (neither do I
particularly want to), but if the two licenses were a pair that I know
to be Free and non-contradictory (e.g. BSD-2-clause and GPL), then the
ftpmasters would (and frequently do) accept files like that in Debian.


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