Feature request: dlopen(NULL, ...

[Michael Fox]

I was wondering if I could get some feeback on an ECL feature request that I posted here: https://gitlab.com/embeddable-common-lisp/ecl/issues/336 <https://gitlab.com/embeddable-common-lisp/ecl/issues/336>

Here is the text:

I would like to be able to call functions using dynamic FFI in the program into which ECL has been embedded.

In Linux, you can do this by calling `dlopen` with `NULL` for the filename.

> If filename is NULL, then the returned handle is for the main
       program.

http://man7.org/linux/man-pages/man3/dlopen.3.html

Looking at ECL source code, it does not seem to be supported. `dlopen` is called in `c/ffi/libraries.d` like this:

      char *filename_string = (char*)filename->base_string.self;
    #ifdef HAVE_DLFCN_H
      block->cblock.handle = dlopen(filename_string, RTLD_NOW|RTLD_GLOBAL);

So, I guess there's no way to set `filename_string = NULL`.

One way to do it would be to say if you call

    (ffi:load-foreign-library "")

Then it will skip the checks to see if the file exists and just call `dlopen(NULL, ...`

Another way would be to make a new function `ffi:load-main-program`.  I don't have any suggestions as to which would be better as I am very new to Lisp.

Thank you for your attention.


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