Variable: buffer-file-read-only
buffer-file-read-only is a buffer-local variable defined in
files.el.gz.
Documentation
Non-nil if visited file was read-only when visited.
Source Code
;; Defined in /usr/src/emacs/lisp/files.el.gz
(defvar-local buffer-file-read-only nil
"Non-nil if visited file was read-only when visited.")