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Re: LGPL-library (tntdb) linked with GPL-library (mysql)

Am Freitag, 25. August 2006 14:15 schrieb Kari Pahula:
> (With apologies to Tommi if he's subscribed to -legal already.)
> On Fri, Aug 25, 2006 at 11:47:49AM +0200, Tommi Mäkitalo wrote:
> > Hi,
> >
> While there would be a problem if a program were to link to both
> OpenSSL library (via, say, postgresql) and mysql, I think that the
> situation might be subtly different in this case due to the way tntdb
> dlopens libraries.
> To state the obvious, just plain having a GPLed program dlopen a GPL
> incompatible library would not differ from the case where regular
> dynamic linking was used.
> Here's what files tntdb has in /usr/lib:
> /usr/lib/libtntdb.so.0.0.0
> /usr/lib/tntdb-mysql.so.0.0.0
> /usr/lib/tntdb-sqlite.so.0.0.0
> /usr/lib/tntdb-postgresql.so.0.0.0
> The first one is the library itself.  The remaining three are all
> libraries that libtntdb might open at run time.  I would expect that
> usually using tntdb would involve dlopening just one of the tntdb-$DB
> libraries.  While it would be possible to dlopen both tntdb-mysql and
> tntdb-postgresql, and thus prevent having the whole work being
> available under the terms of the GPL as required by mysql's license
> (regular GPL with no exceptions for OpenSSL), that would not be the
> usual way to use the library.
Thank you for your clearification.

This means, that it wouldn't be possible to create e.g. a program, which 
accesses a mysql- and a postgresql-database at the same time?

Are dlopened libraries similar to regulary linked libraries? I think there are 
other projects (curl?), which dlopens openssl-libraries to bypass the 
license-restrictions. What about closed source-applications linked with a 
LGPLed tntdb, which are configured to use mysql?

I also thought about LGPL-licsense for libtntdb and GPL for tntdb-mysql and 
GPL+openssl-clause for tntdb-postgresql. This way it will not be possible to 
publish improved drivers based on tntdb-drivers without source, which would 
be good. What about that combination?

As Don told, it looks like it will be ok to LGPL the whole thing. But when 
linking with mysql the LGPL-extension is invalid already, so it seems to make 
sense to leave the LGPL-part away from the mysql-driver.


(Kari: I'm subscribed to debian-leagal - thank you ;-) )

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