Re: question about old patch

[Jakub Jelinek <jakub at redhat dot com>]

On Wed, Mar 10, 2004 at 04:39:23PM -0700, Tom Tromey wrote:
> Jakub, I have a question about this patch:
> 
> 2004-01-20  Jakub Jelinek  <jakub@redhat.com>
> 
> 	* Makefile.am (lib_org_w3c_dom_la_LIBADD,
> 	lib_org_w3c_dom_la_LDFLAGS): New.
> 	(lib_org_xml_sax_la_LIBADD, lib_org_xml_sax_la_LDFLAGS): New.
> 	* Makefile.in: Rebuilt.
> 
> Original post is here:
> 
>     http://gcc.gnu.org/ml/gcc-patches/2004-01/msg02012.html
> 
> Yesterday I looked into a bug report where gij crashed in certain
> circumstances.  It turns out if gij tries to load lib-org-xml-sax.so,
> since this is linked against libgcj.so, we get duplicate registration
> of classes, causing a failure.

The class registration is done through library constructor?
If so, I'd like to know how you can get duplicate registration.
If a library is already loaded, dlopening it (or dlopening some library
which has it as dependency) will not run the constructors again.

> We can fix this by changing these libraries so that they don't depend
> on libgcj.so.  But before doing that I'd like to understand why you
> changed these libraries to link against libgcj.so.

Not linking a shared library against its dependencies is a serious bug
for multiple reasons (symbol versioning, dlopen-ability, prelinking, ...).

	Jakub