anchor.diff:              ((or (= (typeflag entry) +tar-regular-file+)
                    (= (typeflag entry) +tar-directory-file+))
                entry)
  -            ((= (typeflag entry) +posix-extended-header+)
  -             (error "Don't understand POSIX extended header entry"))
               ((= (typeflag entry) +posix-global-header+)
                ;; FIXME: We should make the information from this
                ;; available to the user.  At the moment, however, most
  
positive.code:              (format stream "Invalid tar header checksum ~D (wanted ~D)"
                       (provided condition) (computed condition))))
    (:documentation "Signaled when the checksum in a tar header is invalid."))
  
  ;;; Groveling through tar headers
  
negative.code:              (let ((global-header (read-data-block archive (size entry)
                                                     #'round-up-to-tar-block)))
                 (read-entry-from-archive archive)))
              (t
               (error 'unhandled-read-header-error
                      :typeflag (typeflag entry))))))))
              
  ;;; FIXME: must add permissions handling, mtime, etc.  maybe those should
  ;;; be specified by flags or somesuch?
  