The need for clarifying the GPL exception (unfortunately)

[Etienne M. Gagnon]

Hi Norbert,

I am CC'ing my reply to the classpath-list, as I think it is of general 
interest.

Norbert Bollow wrote:

> ... There needs to be
> something that gives me the right to give grant such linking
> rights to the recipient, otherwise my attempts to grant such
> linking rights are legally null and void.


OK.  I have to agree that there will remain an ambiguity as long as an explicit 
permission to apply the exception to derivative works is added to the Classpath 
exception.

After I received your message, I used Google to search the gnu.org web site 
(including the mailing-list archives) for an explicit FSF statement on the 
subject.  To my dismay, I haven't found any official statements, only some 
contradictory quotes like: (a) the GPL+exc is like the LGPL minus the linking 
problem (b) the GPL+exc is looser than the LGPL on some respects and stricter on 
others (without saying how that is). [I do not remember the exact words, but 
that was the spirit of it.]  What seems clear is: the FSF's exact interpretation 
of the GPL+exc has not been made known officially and publically on their web site.

Now, there's a disturbing fact.  My search on the gnu.org web site lead me to 
re-read some other Licenses, such as the Guile license (wich is GPL + Guile 
exception):

 * As a special exception, the Free Software Foundation gives permission
 * for additional uses of the text contained in its release of GUILE.
 *
 * The exception is that, if you link the GUILE library with other files
 * to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the GUILE library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by the
 * Free Software Foundation under the name GUILE.  If you copy
 * code from other Free Software Foundation releases into a copy of
 * GUILE, as the General Public License permits, the exception does
 * not apply to the code that you add in this way.  To avoid misleading
 * anyone as to the status of such modified files, you must delete
 * this exception notice from them.
 *
 * If you write modifications of your own for GUILE, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.

As you see, it contains an explicit statement about applying the exception to 
derivative work.

Also, http://www.gnu.org/licenses/gpl-faq.html#WritingFSWithNFLibs proposes the 
following text:

 In addition, as a special exception, <name of copyright
 holder> gives permission to link the code of this program with
 the FOO library (or with modified versions of FOO that use the
 same license as FOO), and distribute linked combinations including
 the two.  You must obey the GNU General Public License in all
 respects for all of the code used other than FOO.  If you modify
 this file, you may extend this exception to your version of the
 file, but you are not obligated to do so.  If you do not wish to
 do so, delete this exception statement from your version.

Again, there's an explicit permission to include the apply the exception to 
derivative work.

Classpath's license is thus different from the Guile exception and similarly 
well understood exceptions.  So, in conclusion, you are right, we have probably 
no permission to apply the exception to derivative work.

I will write a message to Richard Stallman, explain to him the problem.

Meanwhile, I do encourage every other VM projects out there, including Kissme, 
Orp, Japhar, etc. (and any other non-FSF project depending on Classpath) to 
consult their lawyer, and be careful, if they have applied any patch to their 
custom version of Classpath.  This is because, under a possible interpretation 
of the Classpath license, a patched Classpath would be GPLed. As "linking" is a 
"modification", this means that running a GPL incompatible application, on top 
of a VM which uses a patched Classpath, links the application with a GPLed (no 
exception) Classpath, and thus possibly infringes on the FSF Copyright.

If this is not the case, it should be made explicit in the Classpath exception; 
this is what I will ask Richard Stallman to do.

Etienne

--
Etienne M. Gagnon                    http://www.info.uqam.ca/~egagnon/
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