Fwd: GPL question about distribution of interface between GPL'ed code and GPL-incompatible software

[Michael Goffioul]

Hi,

Following the thread about octave license and oct files about 2 weeks ago,
I contacted FSF lab for clarification. You can find the answer below (Note
the IANAL disclaimer notice). Basically, you cannot distribute in any form
oct file (or any code that is linked with octave) that is intended to be linked
with GPL-incompatible software: this means any proprietary software, but
also any free software with a GPLv3-incompatible license.

Bye,
Michael.

---------- Forwarded message ----------
From: Brett Smith via RT <address@hidden>
Date: Jan 2, 2008 4:09 AM
Subject: Re: [gnu.org #350033] GPL question about distribution of
interface between GPL'ed code and GPL-incompatible software
To: address@hidden


On Thu, 2007-12-20 at 15:45 -0500, Michael Goffioul via RT wrote:
> Let's take the real-world example that started the discussion on the
> mailing list. National Instrument's LabView is the most used instrumentation
> software used in engineering. This software produces data files in a
> proprietary format. National Instrument provides on their website DLL's
> that allows other programs to read those data files using C++ code,
> but these DLL's are of course closed source. Using these DLL's, it is
> possible to write an Octave module (that would be free software, released
> for instance under GPL) that would read the data and transfer them to
> Octave. Once compiled, this Octave module would be linked against
> the National Instrument's DLL's and against the Octave libraries.
>
> The question is then whether this is allowed. I know that a binary 
> distribution
> of such module is not possible according to GPL. However, the crucial
> point is whether it is allowed to distribute such module under GPL, in
> source form only and separated from the main Octave distribution. So
> it would be up to the user to download the module source code, download
> the NI DLL's, compile and link everything and use it only locally.

Michael,

Distribution of such a plugin in any form is not allowed.  It's only
useful when combined with GNU Octave, so it's a derivative work, even
when distributed independently.  That means that it, and all the code it
relies upon down to the System Libraries, need to be available under a
GPL-compatible license.

If you have further questions, please let me know.

Best regards,

--
Brett Smith
Licensing Compliance Engineer, Free Software Foundation

Please note that I am not a lawyer.  This is not legal advice.