Problem with atexit and _dl_fini

[Florian Weimer]

* Nat!:

> So my problem is, that I observe that my atexit calls are not executed 
> in the correct order.
>
> i.e. atexit( a); atexit( b);  should result in b(), a() being called in 
> that order. To quote the man page,
>
> "the registered functions are invoked in reverse order".
>
>
> When I register with `atexit` I can see my functions being added 
> properly within `__internal_atexit` in the
>
> correct order. Finally after my functions, the elf-loader ? also adds 
> itself there. So it is being called first by
>
> `__run_exit_handlers`.
>
>
> Then comes the part where it goes wrong. I registered my two function 
> with `__internal_atexit`, but for some reason
>
> `_dl_fini` is calling `__cxa_finalize` and that is calling the wrong 
> function first.

When atexit is called from a DSO, glibc calls the registered function
before the DSO is unloaded.  This choice was made because after
unloading, the function pointer becomes invalid.

I haven't checked, but I suspect atexit still works this way even if
it doesn't have to (because the DSO is never unloaded).