(with-dyn-lib "./query.so"
  (deffi query "query" void (closure)))

(deffi-cb query-cb int ((carray char) (ptr (array 1 size-t))))

(query (query-cb (lambda (buf sizeptr)
                   (symacrolet ((size [sizeptr 0]))
                     (let* ((s "Here am I")
                            (l (length s)))
                       (cond
                         ((> l size) 0)
                         (t (carray-set-length buf size)
                            (carray-put buf s)
                            (set size l))))))))