Dynamic loading progress

[Aurélien Aptel]

Hi,

I've tried to test Dave Love's patch [1] but it's now bitrotten, I was
not able to make it work.

So I've started my own thing (drawn from Dave's initial work):

* Use of libtool (ltdl)
  - add configure option for ltdl
  - update dependency in configure.ac / Makefile.in
  - add HAVE_LTDL test macro
* New Lisp function `load-module' which takes a compiled module file
path and loads it
  - check for plugin_is_GPL_compatible symbol
  - check presence of `init' symbol
  - run it as a void (*) () call (no return value/arg).

At first I was calling the libtool init function (lt_dlinit) in
syms_of_lread() but it made every subsequent call to lt_dlopen
segfault. I think the problem was coming from calling it before
dumping because as soon as I moved it to the body of `load-module' it
started working.

It works for very simple stuff so far. If I put a printf in the module
init function it is called successfully. But as soon as I try to use
DEFUN, gcc complains:

In file included from fmod.c:17:0:
fmod.c:30:16: error: ‘Ffmod’ undeclared here (not in a function)
 DEFUN ("fmod", Ffmod, Sfmod, 2, 2, 0,
                ^
emacs-master/src/lisp.h:2688:26: note: in definition of macro ‘DEFUN’
        { .a ## maxargs = fnname },     \
                          ^

So I'm stuck here for now... Any help/feedback welcome :)

I've attached a patch and an example module (compilation/loading
instructions in comments). ltdl is enabled by default in the configure
script, you just need libtool in order to try it. I know it is not as
polished as Dave's patch, I'm just trying to get it to work before
making it clean.

1: http://www.loveshack.ukfsn.org/emacs/dynamic-loading/

dynamic-loading.diff
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fmod.c
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