two emacs lisp functions to lock buffers

lock-view.el

(defun lock-view ()
  "put all visible buffers in view mode"
  (interactive)
  (save-window-excursion
    (mapcar (lambda (win)
              (with-current-buffer (window-buffer win)
                (unless buffer-read-only
                  (view-buffer (current-buffer)))))
            (window-list))))

(defun lock-buffers-visiting-directory (dir)
  (interactive "DDirectory:")
  (save-window-excursion
    (dolist (buf (buffer-list))
      (when (and
             (buffer-file-name buf)
             (string-prefix-p dir (buffer-file-name buf)))
        (with-current-buffer buf
          (unless buffer-read-only
            (view-buffer buf)))))))