[Mono-devel-list] ByteFX development

Jonathan Pryor jonpryor at vt.edu
Wed Sep 22 07:24:00 EDT 2004

On Tue, 2004-09-21 at 22:00, Joshua Tauberer wrote:
> Jonathan Pryor wrote:
> > So, to simplify (is that safe?), your program must be GPL'd if it
> > directly or indirectly relies upon GPL'd facilities, *unless* it's "just
> > data" for those facilities.
> This can't be the end of the story, though.  If you start the sentence 
> "Your program must be GPLed if...", the end of the sentence has to have 
> something to do with making copies of someone else's copyrighted work.

Which is why the GPL needs some *serious* clarification in the context
of dynamic linking.

> What I'm getting at is this: There has to be a reason, based in law, for 
> why the GPL license would be binding on me as a developer.  Normally, 
> people can't tell me how I have to license my work.  Why can the GPL 
> force me to do something?

"Normally," the GPL can force you to do something because you're
creating a derivative work (based on copyright law), and/or because
you're copying/distributing the GPL'd code.  The GPL states that it only
covers copying, distribution, and modification.

Consequently, the GPL can force you to do something if: (1) you modify
the GPL'd work (in which you're *definitely* creating a derivative work
as far as copyright is concerned), and (2) you copy/distribute the GPL'd
work along with your own.  Static linking is the conventional example. 
This has some interesting consequences if you *don't* copy/distribute
the GPL'd work, which I touch upon below.

> It's *not* because I agreed to the GPL when I downloaded GPL software, 
> or when I used a GPL program.  The GPL isn't an EULA or click-through 
> "license" -- the GPL is not a contract.  (I read a good explanation 
> about this somewhere, but it was long ago so I don't have a reference 
> off hand.)

You probably read it at groklaw.net. :-)

> There are circumstances, however, when I'm legally not allowed to make 
> copies of my own work (oversimplification alert).  If my code is a 
> derivative of or contains someone else's code, copyright law says I 
> cannot distribute my code without the permission of the owner of the 
> other code.


> Now the GPL comes into the picture.  When code is released under the 
> GPL, it's a blanket statement giving anyone permission to distribute 
> derivatives or combinations of the GPLed code.  Except, it only gives 
> permission to you if you agree to a few things, one of which is that you 
> have to GPL your code too.
> So the moral of the story is that you're only bound by the GPL if you 
> are attempting to make copies of something that 1) you don't hold the 
> copyright on, 2) you don't have specific permission from the copyright 
> holder to make copies of, and 3) the code has been released under the GPL.
> "Relying on" and "making copies of" are two different things, and only 
> the latter is illegal without a license.  When copyright law is not 
> involved, neither is the GPL.

The implication of this is as follows: You can create a proprietary
program, link against a GPL'd library (readline, for example), and be in
the clear *if* you never actually copy/distribute the library.  You
could instead require that the user download/install readline

This is the joy of dynamic linking, and by that thought process would
completely destroy the intent of the GPL -- a proprietary app could link
against a GPL'd library without any problems (aside from slightly more
complicated installation instructions for the user).

The logic to this is as follows: the GPL clause 0 defines a "work based
on the program" as "either the Program or any derivative work under
copyright law...a work containing the program or a portion of it, either
verbatim or with modifications..."  With dynamic linking, and especially
with packaging solutions like RPM and PKG, the proprietary app would
never contain a GPL'd work or a portion of it (aside, perhaps, from
function names used by the dynamic linker, and function names should be
"fair use" since I could re-implement readline, using the same function
names for compatibility).

Obviously this interpretation would be frowned upon by rms and company. 
Alas, this thought process isn't covered on the GPL faq, so I have no
idea what reason rms would have for preventing dynamic linking, but I'm
sure there is one.  I hope.

Things get more confusing with GPL section 3.  Readline is included with
most Linux distributions, so is it part of the OS?  If it is, then
proprietary apps can link against it at will and not follow the GPL.



> So who decides whether referencing a GPLed assembly ends up with a 
> derivative work?  Not the GPL, and not the owner of the GPL code.  Only 
> courts can decide, because only courts can decide whether something is 
> copyright infringement.  Since a court hasn't taken up this topic yet 
> (unless there's somehow applicable precedent), it's entirely undefined.

Let's hear it for the courts, and a system of laws so complex we need a
lawyer around to even *contemplate* doing anything complicated!
Hip hip, hooray!

Of course, simple laws would be more easily broken, so I'm not sure what
the solution to this problem is either, but it's easier to complain than
to fix the system... :-(

 - Jon

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