RE: [PATCH 1/3] elf: Allow dlopen of filter object to work [BZ #16272]

[David Kilroy <David dot Kilroy at arm dot com>]

> Florian Weimer
> 
> * David Kilroy:
> 
> >> Is there an expectation that libinternal interposes symbols in libA
> >> etc., perhaps with more efficient implementations?  And if not, a
> >> fallback implementation in libA etc. is used?  This is clearly not
> >> supported by the Solaris filter feature (as documented).
> >
> > I'm not sure what you mean here. Libinternal.so is expected to supply
> > the implementations for the symbols in libA.so. Ideally we wouldn't
> > pick up other symbols from libinternal, but this is not an issue for
> us.
> > If libinternal.so were to use IFUNC relocations for libA's symbols, I
> > would hope it works, but I don't think that's being done.
> 
> I mean something like this.  libA defines f1, f2, f3.  libinternal
> replaces f1 and f3 with optimized implementations, but not f2.
> Applications which call f2 are expected to get the unoptimized
> implementation in f2.

Ah, no we don't do that. Our filter libraries would only contains stubs.
The real implementation for all functions would live in libinternal.so.


Thanks,

Dave.