Lepton EDA 1.9.14 announce and misc questions

[Vladimir Zhbanov]

Hi Guile users and devs,

I'm the current maintainer of Lepton EDA suite, an about five year
old fork of geda-gaf with accent to moving more functionality to
Scheme code.  I'm not sure if it is acceptable to advertise it
here, please let me know if not.  I just know several Guix
packagers are reading this mailing list and would like to announce
a new version of Lepton, 1.9.14 has been released on April, 7:

https://github.com/lepton-eda/lepton-eda/releases/tag/1.9.14-20210407

Lepton supports Guile 2.0, 2.2, and 3.0.  There are lots of C code
involved and one of our current goals is untangling it and moving
our Scheme functionality to FFI as much as possible.  Hence, the
issue I recently stumbled upon.

Having the following code:

(define-public (sys-data-dirs)
  "Returns a list of search directories for system data."
  (let ((pointer (eda_get_system_data_dirs)))
    (let loop ((num 0)
               (ls '()))
      (let ((string-pointer
             (dereference-pointer
              (make-pointer (+ (pointer-address pointer)
                               (* num (alignof '*)))))))
        (if (null-pointer? string-pointer)
            (reverse ls)
            (loop (1+ num)
                  (cons (pointer->string string-pointer)
                        ls)))))))

is it permissible to use 'alignof' (or 'sizeof') this way here, if
at all?  Or some pitfalls may exist?

The function gets the C array of strings and translates them into
a Scheme list.  I just don't want to write an additional C layer
to process the array, but I'm in doubt if it could shoot me in the
foot on some OS/arch combinations.

Thanks in advance,
  Vladimir