Re: [PATCH v6 15/20] elf: Run constructors if executable has a soname of a dependency

[Florian Weimer <fweimer@redhat.com>]

* Adhemerval Zanella:

> The DSO constructor should not be ignored if the main executable
> has the SONAME set to a dependency.  It fixes the case where
> (using the scripts/dso-ordering-test.py definition):
>
>   {}->a->b->c;soname({})=c
>
> Where the constructors should return
>
>   c>b>a>{}<a<b<c

I'm a bit unclear what is this trying to fix.

It reminds me of this change:

commit 9ffa50b26b0cb5d3043adf6d3d0b1ea735acc147
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Dec 11 17:30:03 2020 +0100

    elf: Include libc.so.6 as main program in dependency sort (bug 20972)
    
    _dl_map_object_deps always sorts the initially loaded object first
    during dependency sorting.  This means it is relocated last in
    dl_open_worker.  This results in crashes in IFUNC resolvers without
    lazy bindings if libraries are preloaded that refer to IFUNCs in
    libc.so.6: the resolvers are called when libc.so.6 has not been
    relocated yet, so references to _rtld_global_ro etc. crash.
    
    The fix is to check against the libc.so.6 link map recorded by the
    __libc_early_init framework, and let it participate in the dependency
    sort.
    
    This fixes bug 20972.
    
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>

Is it a more general/correct version of this commit?

But if the main program has a soname, wouldn't we stop loading it as a
dependency, too?  So that the expected ouptut turns into:

  b>a>{}<a<b

because the separate c is not actually loaded.

Thanks,
Florian