> > I am not a lawyer (far from that), not even a GNU lawyer. However, I used
> > to think that LGPL precisely does not apply to shareable libraries (.so),
> > but only to object libraries (.a).
> >
> > When you distribute a commercial software on Linux (for instance), you do
> > NOT redistribute any .so file, you use the one that is on the end-user's
> > system. On the other hand, you redistribute part of the content of the
> > .a files. This is why, in my opinion, LGPL applies to .a files, while
> > GPL is fine for .so files.
> 
> The FSF doesn't agree; in their opinion, a lot of the technical
> arguments are moot, as what will rule the day in court is the legal
> arguments. And in their opinion, linking is linking, and will be
> treated the same in court.

OK, let's be specific.

Consider a GPL executable file (say the GNU "ls") and a GPL shared
library (say "libfoo.so").

1) You say that referencing the symbol "foo" from libfoo.so and linking
   against libfoo.so makes your application fall under GPL. Right?

2) If you write (C code, sorry):

     system ("ls");

   your application does not fall under GPL because you don't *link*
   against the executable file "ls". Right?

3) Now let's assume that you don't reference the symbol "foo" any more
   and you replace your procedure call by:

     handle = dlopen ("libfoo.so", ...);
     foo_p = dlsym (handle, "foo");
     (*foo_p) (....);

   You no longer *link* against libfoo.so. There is no stronger interaction
   between your application and libfoo.so than you have with "ls" when you
   use system().

   However, the result is technically identical to point 1.

   So, do you fall under GPL in this case?

The word "link" no longer have a specific meaning these days...

-Thierry
____________________________________________________________________________

Thierry Lelegard, "The Jazzing Troll", Email: thierry.lelegard@canal-plus.fr
CANAL+ Technologies, 34 place Raoul Dautry, 75906 Paris Cedex 15, France
Tel: +33 1 71 71 54 30   Fax: +33 1 71 71 52 08   Mobile: +33 6 03 00 65 75
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