Re: A question about pure static linking with libdl

[Jon Chesterfield <jonathanchesterfield@gmail.com>]

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I think using dlopen in static binaries is an interesting (though niche)
use case. I'm subscribed to this list with a vague intention of
implementing it but haven't found the time.

The application of interest to me is a plugin architecture where the main
executable is static, mostly so it's easier to distribute, and the plugged
in components are independent of any libc. Essentially trying to use elf as
part of a jit loading mechanism.

No eta on this work though. Could be years :(

Cheers

On 16 May 2017 17:30, "Szabolcs Nagy" <nsz@port70.net> wrote:

* John Hu <heat0415@gmail.com> [2017-05-16 15:40:28 +0800]:
> Recently I have an experiment about whether full static-linked ld.gold
with
> plugin function enabled can use its --plugin option to dynamically load
> plugins such as LLVMgold.so. I use "./configure --enable --enable-plugins
> --disable-werror LDFLAGS="-static" "  to generate a full statically linked
> ld.gold which does not have any dynamic library dependency, then I exec
> "./ld.gold --plugin LLVMgold.so" but an error occurs that "could not load
> plugin library: Dynamic loading not supported". I doubt this is a bug
> because it is claimed that musl supports full static linking but I am not
> sure about that. BTW, my experiment environment is Alpine 3.5.

dlopen is not supported in static linked binaries yet, that is non-trivial
to support and in your use case it does not make sense: the loaded lib is
linked against the host libc (and many other libs) and is in a package that
is updated independently of the libc, there is no guarantee that the static
linked libc is compatible with the host libc (and if there is then you
don't really need static linking anyway, you could get the same effect
by using your custom libc to launch ld.gold as ./mylibc.so ld-gold ).

>
> Now I send this email again because I want this email to be replied
> according to "If you are not subscribed and want to receive a reply,
please
> mention in your email that you want to be Cc'd." in the website.

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