[H-GEN] GPL question

Paul Gearon pag at pisoftware.com
Mon Jan 5 21:55:54 EST 2004



Anthony Towns wrote:
> You have a shared library licensed under the GPL, called libgpl. You have
> a program, foo, that you don't want to license under the GPL. Distributing
> the library requires you to obey the GPL, and especially if you distribute
> libgpl and foo together, it's hard to claim that the entire work is
> "mere aggregation" rather than a derived work of libgpl, and thus must
> be licensed under the GPL in its entirety.

If you were concerned about that, then the simple solution is to simply 
say "this software requires that libgpl be installed on your system" and 
then not bother distributing libgpl at all.

> If you're not distributing libgpl though -- maybe "libgpl" is actually
> Qt, and is already installed everywhere

Ahhh!  Thank you.  I'd forgotten that QT falls into this category.  My 
question was actually hypothetical in an attempt to better understand 
the licence.  My question also stems from the countless arguments I've 
heard (from non-lawyers) about how you can't link non-GPL code with GPL 
code.  While trying to work it all out I thought I'd garner the opinions 
of the HUMBUG membership on the issue.

> -- the only ways you could
> be misbehaving is by your program nevertheless being a derived work
> of libgpl -- and that's not unreasonable, considering you probably had
> libgpl around when developing and compiling foo, you said -lgpl on the gcc
> command line eg -- or if you're encouraging people to act infringingly,
> and can get done for contributory infringement.

Now derivation is an interesting point.  The GPL *does* mention deriving 
your work from GPLed code (section 2 refers to this).  However, wouldn't 
section 0 be the first consideration here?  Again, it says: "Activities 
other than copying, distribution and modification are not covered by 
this License; they are outside its scope."  So isn't it true that if the 
"derivation" does not involve copying, distribution, or modification, 
then the GPL will not apply?

> The analogy that's usually drawn is that if static linking is illegal,
> then dynamic linking will leave you just as liable, since you're just
> using it as a technical measure to try to avoid culpability. I'm not sure
> that sort of reasoning holds up, though [0].

I'm not sure I agree with this analogy.  After all, in static linking 
you are actually including a GPLed object (the object code in a static 
library is covered by the GPL as per the phrase: "the output from the 
Program is covered only if its contents constitute a work based on the 
Program").  The included parts of the static library are first copied 
into your binary, and then distributed by you.  This clearly falls into 
the domain of what the GPL licenses.

In contrast, dynamic linking does not require copying, modification, nor 
distribution.

> I think it's pretty questionable too, personally, but I'm not a lawyer.

Nor I, but I'm willing to learn.  :-)

-- 
Regards,
Paul Gearon

Software Engineer                Telephone:   +61 7 3876 2188
Plugged In Software              Fax:         +61 7 3876 4899
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immane mittam.
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