(in-package #:cffi-additions)

(defun foreign-function-exists-p (name)
  (when (cffi:foreign-symbol-pointer name)
    t))

(defun choose-foreign-function (&rest names)
  (loop
     for name in names
     when (foreign-function-exists-p name)
     do (return name)))

(defvar *libc-implementation-memoized*)
(defvar *libc-version-memoized*)

(defun libc-implementation ()
  (when (boundp '*libc-implementation-memoized*)
    (return-from libc-implementation *libc-implementation-memoized*))
  (setq *libc-implementation-memoized*
	(cond ((foreign-function-exists-p "gnu_get_libc_version")
	       :gnu))))

(defun libc-version ()
  (when (boundp '*libc-version-memoized*)
    (return-from libc-version *libc-version-memoized*))
  (setq *libc-version-memoized*
	(case (libc-implementation)
	  (:gnu
	   (foreign-funcall "gnu_get_libc_version" :string)))))