[vlc-devel] reenabling java bindings

[Olivier Aubert]

On Fri, 2008-12-12 at 14:33 +0100, Rémi Denis-Courmont wrote:
> > There's surely something I'm missing in the way java loads libraries,
> > since checking the java source code I've seen it uses dlopen (are there
> > any other means to load a library?).
> Link at build time, and let the run-time linker do the job.
> That's how VLC loads libvlc, and how libvlc loads libvlccore.
libvlc does not dlopen(libvlccore) explicitly. libtool does its job, and
libvlc is simply compiled against -lvlccore, which the loader resolves
at runtime.
With your approach, all other mentionned systems (java bindings, python
bindings, mozilla plugin) should have to explicitly load libvlcore with
something like

if (!dlopen ("libvlccore.so", RTLD_NOW | RTLD_GLOBAL))
  printf ("\n%s\n", dlerror());
(with an additional #define to use .dll instead of .so for windows, etc).

so that libvlccore symbols are available for subsequently loaded vlc modules.
It is not undoable, but looks hackish to me: since plugins use symbols
from libvlccore, we should simply link them with libvlccore, not rely on
user code to do that.

> > So I ask to make that plugin linking against libvlccore configurable
> > with a specific switch from configure and disabled by default, until
> > loading from java is sorted out (I locally reverted the changes on that
> > commit, and the java bindings work again as expected). I will proceed
> > with this modification after a general agreement on this change.
> I disagree. The way plugins link back into libvlccore makes this approach
> fundamentally unsafe: a plugin must link against the libvlccore image that
> loaded the plugin. We have had multiple reports of obnoxious crashes due to
> that, and that's not counting those people who ran away without bothering
> to report the problem.
I would be curious to have explicit references to such "multiple reports
of obnoxious crashes due to that". Not that I question your affirmation,
but I would like to investigate the issue to better understand its
whereabouts.

Olivier