Re: Trouble with portable linking

[Ryan Burn <rnickb731@gmail.com>]

On Thu, Dec 17, 2020 at 12:55 PM Florian Weimer <fw@deneb.enyo.de> wrote:

> > If I understand correctly, newer versions of glibc will resolve a
> > versioned symbol even if the embedded soname doesn't match. Is there a
> > way to explicitly define the soname so that I can specify it to
> > libpthread?
>
> The link editor copies the soname of the shared object that contains a
> versioned symbol definition when it generates the versioned symbol
> reference.  That's why I think you need that stub DSO.  It's the only
> way I know of that actually works.

What if I link a minimal static library libstub.a like this

// stub.c
__asm__(".symver pthread_getattr_np,pthread_getattr_np@GLIBC_2.2.5");

int __wrap_pthread_getattr_np(pthread_t thread, pthread_attr_t* attr) {
  return pthread_getattr_np(thread, attr);
}

On an older machine where libpthread contains the symbol and then add
libstub.a when I link my DSO in the newer build environment? Would
that work or is the embedded soname determined at the final linking
stage?

Is there any way to view embedded sonames using objdump or readelf?