Copied Offers

[Ben Tilly]

On 9/26/06, Matthew Flaschen <matthew.flaschen at gatech.edu> wrote:
> I found another FAQ Entry
> (http://www.gnu.org/licenses/gpl-faq.html#RedistributedBinariesGetSource)
> that says:
>
> "My friend got a GPL-covered binary with an offer to supply source, and
> made a copy for me. Can I use the offer myself to obtain the source?
>      Yes, you can. The offer must be open to everyone who has a copy of
> the binary that it accompanies. This is why the GPL says your friend
> must give you a copy of the offer along with a copy of the binary---so
> you can take advantage of it."
>
> According to this interpretation, any copy of the offer is valid with
> any copy of the binary.
>
> This answer supports my argument, except for its claim that the offer is
> only valid for those who have a binary.  I don't see how this
> requirement is stated in the GPL.

It is not.  However logically, the fact that it is available for those
with a binary doesn't imply that it can't also be open for those
without a binary. :-)

As for quoting that FAQ as an authoritative reference, I wouldn't.  It
represents reality as RMS and the FSF want it to be.  This is
informative, but well-educated people don't always think they are
right.  The classic eample is
http://www.gnu.org/licenses/gpl-faq.html#LinkingWithGPL.  RMS and the
FSF want you to believe that linking automatically causes a copyright
issue that causes the GPL to apply.  However it really isn't that
simple.

The act of linking proprietary and GPLed code does create an aggregate
that has both copyrights applied to it.  You certainly can't
distribute the result.  However virtually nobody would want to.  (If
you're using virtualization software, like Xen or vmware, you might
become an exception to that rule.)  The question then is whether or
not programming the interface with software that you're going to link
to is derivative enough that your code is a derivative under copyright
law of the code you're linking to.  This is a very difficult question
and it does *not* have a simple answer.

It is instructive in this regard to look at Linus Torvalds' changing
answers over time on loadable binary kernal modules.  One thing
remains constant - whether or not the GPL applies is a question of
whether the module is derivative under copyright law.  Two things
change.  The first is that the interface that is exposed grows richer
over time (so you're more likely to be derivative), and the second is
that Linus grows more annoyed over time with some of the more
egregious attempts to avoid the GPL.

You can read a collection of his answers at
http://linuxmafia.com/faq/Kernel/proprietary-kernel-modules.html.  And
you'll see his arguments for why linked code might or might not be
impacted by the GPL.  (Note that most of the time he thinks it is.  He
agrees with the FSF answer most of the time.)

IANAL, this is not legal advice, etc.

Cheers,
Ben