(use-modules (rnrs bytevectors)
             (ice-9 binary-ports))

(define MAX_SIGNED_INT 2147483647)
(define BYTES_TO_READ 10)

(define (traverse port)
  (let* ((file-sz (stat:size (stat port)))
         (ua (make-bytevector BYTES_TO_READ 0))
         (cur-offset 0))
    (let lp ((cur-offset (seek port (- MAX_SIGNED_INT 1000) SEEK_CUR)))
      (when (< cur-offset (- file-sz BYTES_TO_READ))
        (lp (seek port BYTES_TO_READ SEEK_CUR))))
    (close-port port))) 

(define port (mkstemp! (string-copy "/tmp/big-file-XXXXXX")))
(truncate-file port #e2.5e9)
(traverse port)