Method: (TEMPLATE-TRUENAME FILE-SYSTEM-GENERATOR PATHNAME)

Source

(defmethod template-truename ((generator file-system-generator) (name pathname))
  (dolist (root (root-directories generator))
    (when-bind truename (probe-file (merge-pathnames name root))
       (return-from template-truename truename)))
  (return-from template-truename nil))