A real FFI patch would let me dlopen any C library and call
functions within
it, such as openssl or zlib. Dave's patch is more like what Python
allows:
writing Emacs Lisp extensions in C that can be loaded as shared
libraries.
That sounds right, thank you.
Just for the record: Emacs's FFI should not be able to open just any
random shared library. Only the ones that come with the needed extra
"I'm compatible with the GPL" branding (as attested by the
presence of the "plugin_is_GPL_compatible" symbol, IIRC).
Hopefully, more and more libraries will come with such branding in
the future.