Here's a code snippet I've used in my patch to sb-bsd-sockets, that implements something similar to your "Shareable Byte Vectors" for SBCL. Tested with recvfrom and sendto.

[ François-René ÐVB Rideau | Reflection&Cybernethics | http://fare.tunes.org ] The ultimate result of shielding men from the effects of folly is to fill the world with fools. -- Herbert Spencer

;;; This little protocol could and should be used in a whole lot of I/O functions. ;;; It silently assumes that buffers are big enough to fit the length required, ;;; and are either subtypes of characters or integer, and that data will fit. (deftype iobuffer () "buffer for direct I/O" '(simple-array (unsigned-byte 8) (*))) (defun iobufferp (x) "check if X is a proper iobuffer" (typep x '(iobuffer))) (defun iobuffer-to-data (buffer data &optional (length (length buffer))) "copy contents of iobuffer to data array" (if (subtypep (array-element-type data) 'integer) (replace data buffer :end1 length) (loop for i from 0 below length do (setf (char data i) (code-char (aref buffer i)))))) (defun data-to-iobuffer (data buffer &optional (length (length data))) "copy contents of data array to iobuffer" (if (subtypep (array-element-type data) 'integer) (replace buffer data :end1 length) (loop for i from 0 below length do (setf (aref buffer i) (char-code (char data i)))))) (defun ensure-iobuffer-from-data (data &optional (length (length data))) "if data is not an iobuffer already, create a new one with similar contents" (if (iobufferp data) data (let ((buffer (make-array (list length) :element-type '(unsigned-byte 8)))) (data-to-iobuffer data buffer length) buffer))) (defun prepare-iobuffer-for-data (data &optional length) "if data is not an iobuffer already, create a new one with same length" (if (iobufferp data) data (make-array (list length) :element-type '(unsigned-byte 8)))) (defun commit-iobuffer-to-data (buffer data &optional length) "if data is not an iobuffer already, replace its contents with those of given buffer" (unless (eq buffer data) (iobuffer-to-data buffer data length))) (defmacro with-iobuffer-sap ((buffer data &key (direction :input) length) &body body) "bind buffer with an iobuffer suitable for I/O of given direction, to be committed to/from the contents of data array data" (let ((data-tn (gensym)) (length-tn (gensym))) `(let* ((,data-tn ,data) (,length-tn ,length) (,buffer (ecase ,direction (:input (prepare-iobuffer-for-data ,data-tn ,length-tn)) ((:output :io) (ensure-iobuffer-from-data ,data-tn ,length-tn))))) (prog1 (sb-sys:with-pinned-objects (,buffer) (let ((,buffer (sb-sys:vector-sap ,buffer))) ,@body)) (case ,direction ((:input :io) (commit-iobuffer-to-data ,buffer ,data-tn ,length-tn))))))) ;;; Should I add a :start argument for the data? ;;; Have :start and :end instead of :start and :length?