[Bug dynamic-link/30007] rfe: dlopen to user buffer or to specified address

["stsp at users dot sourceforge.net" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=30007

--- Comment #2 from Stas Sergeev <stsp at users dot sourceforge.net> ---
(In reply to Adhemerval Zanella from comment #1)
> Any GNU extension requires a specific usercase that can't be easily
> accomplished with current API. What problem are trying to solve that you
> require to map a shared library to an specific pre-allocated address?

It needs to interact with legacy
32bit code that is running in VM.
The memory of the VM is mapped in
a 64bit space under a particular
address. I need to be able to load
solib within a 4Gb range from the
aforementioned address, in which
case the 32bit code will be able
to create the pointers to that
solib's objects.
Another way of solving that, is to
put the solib into a MAP_SHARED buffer.
In this case I will be able to create
the "mirror" of that solib under
any address I need, so the 32bit
pointers will likely work in that
case too (I will not execute functions
via pointers to that window). For
that, I'd probably need the following
API:
void *dladdr(void *handle, int *buffer_size_out);
So the ability to get the address
and length is probably already enough
for my needs, as that will allow me
to do the MAP_SHARED trick. And that
can probably be made an LD_AUDIT extension,
instead of a new global function.

Of course I still need to test either
way to make sure it really works. Which
may mean that eventually I'll have to
implement that extension myself. So for
now this is just a query to find out
if it is acceptable, and if so - in what
form.

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