anchor.diff:              (disk (file-host-mount-device host))
               (dirty-bit nil)
               (abort-action nil)
  +            (buffer nil)
               (buffer-position)
  +            (block-n -1)
               (file-length 0)
               (file-position 0))
           (cond ((null file-offset)
  
positive.code:                               :if-exists if-exists
                                :block-size (bytes-per-cluster ffs)
                                :dirty-bit dirty-bit
                                :buffer-position buffer-position
                                :position file-position
                                :length file-length
  
negative.code:                  (:create
                    (multiple-value-setq (buffer-position dir-array file-offset)
                      (create-file host dir-array dir-cluster (pathname-name pathname) (pathname-type pathname) nil (ash 1 +attribute-archive+)))
                    (setf buffer (make-array `(,(bytes-per-cluster ffs)) :element-type '(unsigned-byte 8))
                          block-n 0
                          dirty-bit t
                          abort-action :delete))
                   ((nil)
                    (return-from open-using-host nil))))
  