Re: two instances of global from shared lib linked with -Bsymbolic

[Alan Modra]

On Tue, Apr 06, 2004 at 03:41:52PM -0400, Ian Lance Taylor wrote:
> Rafal Dabrowa <address@hidden> writes:
> >     void fun1() { ... }
> >     void fun2() { fun1(); ... }
> > 
> > Function fun2 invokes fun1. I want up to fun2 would always invoke fun1 from 
> > my 
> > library. It is surprising for me, that if I create fun1 in main program, 
> > then 
> > fun2 invokes fun1 from main program instead of library. From this reason I 
> > have added -Bsymbolic option.
> 
> If you want to guarantee that fun2 calls fun1, and you also want to
> make it possible for programs linked against the shared library to
> call fun1 in the shared library, then there is no simple way to do
> this.

If fun1 is made protected, then the library will behave as Rafal
desires.  See gcc's info on function attributes.

void __attribute__ ((visibility ("protected")))
fun1 () { ... }

I've thought before that a useful extension to our ld version scripts
would be to have a "protected" keyword in addition to "global" and
"local".

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre