(setq c-basic-offset 4)
(if (not (word-search-forward "Mode: C" nil t))
    (insert-string "/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 4 -*- */\n\n"))
(mark-whole-buffer)
(indent-region (region-beginning) (region-end) nil)