+(defclass buffer-stream (sb-gray:fundamental-binary-input-stream sb-gray:fundamental-binary-output-stream)
+ ((buffer :initform (make-array 128
+ :element-type '(unsigned-byte 8)
+ :adjustable t
+ :fill-pointer 0))
+ (mark :initform 0)))
+
+(defmethod stream-element-type ((stream buffer-stream))
+ '(unsigned-byte 8))
+
+(defmethod sb-gray:stream-read-sequence ((stream buffer-stream) seq &optional (start 0) end)
+ (let* ((buffer (slot-value stream 'buffer))
+ (end (or end (length seq)))
+ (mark (slot-value stream 'mark))
+ (fill-pointer (fill-pointer buffer))
+ (new-mark (+ mark (min fill-pointer (- end start)))))
+ (setf (slot-value stream 'mark) new-mark)
+ (replace seq buffer
+ :start1 start :end1 end
+ :start2 mark :end2 fill-pointer)
+ (min end (+ start (- fill-pointer mark)))))
+
+(defmethod sb-gray:stream-write-sequence ((stream buffer-stream) seq &optional (start 0) end)
+ (let* ((buffer (slot-value stream 'buffer))
+ (end (or end (length seq)))
+ (fill-pointer (fill-pointer buffer))
+ (new-fill (min (array-total-size buffer) (+ fill-pointer (- end start)))))
+ (setf (fill-pointer buffer) new-fill)
+ (replace buffer seq
+ :start1 fill-pointer
+ :start2 start :end2 end)
+ seq))
+
+(with-test (:name :run-program-cat-3)
+ ;; User-defined binary input and output streams.
+ (let ((in (make-instance 'buffer-stream))
+ (out (make-instance 'buffer-stream))
+ (data #(0 1 2 3 4 5 6 7 8 9 10 11 12)))
+ (write-sequence data in)
+ (let ((process (sb-ext:run-program "/bin/cat" '() :wait t :output out :input in))
+ (buf (make-array (length data))))
+ (assert (= 13 (read-sequence buf out)))
+ (assert (= 0 (read-sequence (make-array 8) out)))
+ (assert (equalp buf data)))))
+