Re: Dynamic libraries linking problem with Libtool

[Ralf Wildenhues]

Hello Roberto,

* Roberto Rigamonti wrote on Thu, Mar 06, 2008 at 04:23:31PM CET:
> Hi, I've already posted a related question on
> http://www.linuxquestions.org/ today, but it seems that nobody there is
> Libtool-expert so I've decided to crosspost here.
> I've put a detailed explanation of my problem here:
> http://www.linuxquestions.org/questions/programming-9/c-dynamically-loaded-libraries-and-automake-invalid-elf-library-error-626105/
> By the way, the situation is the following: using Autotools and Libtool
> I created a source tree for a project composed of a main program and a
> set of libraries that must be loaded at runtime by the program
> (plugins). Before starting real coding, I decided to write down a test
> program, because I'm not accustomed with Autotools and I had always used
> the traditional hand-compiling and linking against .so libraries.
> Now, as explained thoroughly in the page linked above, I'm faced with a
> .la library that seems to be requested by my main program, but when I
> provide it, the program refuses it because it is a Libtool archive and
> not a ELF file.

If you use dlopen directly, then you should continue to load .so modules
directly.  Loading of libtool modules (.la files created with -module)
works when you use libltdl and its lt_dlopen function.  libltdl is
documented here:
<http://www.gnu.org/software/libtool/manual/html_node/Using-libltdl.html>

If you want to see a small example package that uses libltdl, besides
what's in the manual, look in the source tree of Libtool in the
tests/mdemo directory (Libtool version 2.2) resp. the mdemo directory
(version 1.5.x).  Note that its Makefile.am file is much more
complicated than it would need to be just for a demo, because mdemo is
also used for some tests.

> I'm close to getting insane, it's about 10 hours I'm
> trying to get out of this, and I read a huge number of docs/tutorials on
> the web without result.

Don't get insane by working 10 hours without progress.  Ask after a
couple of hours.  ;-)

> I've put the whole source tree on the web
> http://digilander.libero.it/optikstorm/3DVisor-0.0.1.tar.bz2 (~250Kb),
> hoping that this helps.

If the above advice does not help you get further, please ask more
specific questions; I might look into the package then.

Cheers,
Ralf