+ (let ((length (loop for offset of-type fixnum upfrom 0
+ until (zerop (sap-ref-8 sap offset))
+ finally (return offset))))
+ (let ((result (make-string length :element-type 'base-char)))
+ (sb!kernel:copy-from-system-area sap 0
+ result (* sb!vm:vector-data-offset
+ sb!vm:n-word-bits)
+ (* length sb!vm:n-byte-bits))
+ result))))