Re: ltdl support for versioned symbols

[Ralf Wildenhues]

* Ludovic Courtès wrote on Sun, Mar 13, 2011 at 05:31:17PM CET:
> Ralf Wildenhues writes:
> > * Ludovic Courtès wrote on Sat, Mar 12, 2011 at 02:35:11PM CET:
> >> I’m thinking about adding this to ltdl:
> >> 
> >>   void *lt_dlvsym (lt_dlhandle HANDLE, const char *NAME,
> >>                    const char *VERSION);
> >> 
> >> On GNU systems[*], this would call ‘dlvsym’; on other systems, it would
> >> call ‘lt_dlsym’.
> >
> > Hmmyes, maybe.
> >
> > You know about copyright assignment for nontrivial additions, HACKING,
> > and that we love to see testsuite coverage for new features, I suppose?
> > ;-)
> 
> I do :-), I just wanted to make sure there’s interest in it.

Well, it's a bit of a bummer that encoding of a symbol version can not
be done in a portable manner.  That makes this abstraction rather leaky.

> >> [*] Solaris ld supports symbol versioning but seems to lack ‘dlvsym’.
> >
> > However, it seems to have a bit weaker way of verifying the presence of
> > some version in a shared library by calling dlsym (handle, version):
> > http://www.shrubbery.net/solaris9ab/SUNWdev/LLM/p26.html#CHAPTER5-IX522
> 
> That doesn’t seem very useful to me because there’s nothing you can do
> if a given symbol is available under several versions, and it doesn’t
> allow you to know whether the symbol you’re interested in available in a
> specific version.

But at least it could tell you if such a version is not available at
all, no?

> > Maybe there is a way to exploit this reduced functionality as well.
> > Can you test on Solaris?
> 
> Yes.
> 
> I’ll see what I can do and report back.

Thanks!
Ralf