- /* Clear write mode */
- f->wpos = f->wstop = f->wend = 0;
-
- /* Put the file in read mode */
- if (!f->rpos) f->rpos = f->rend = f->buf;
-
- /* If unget buffer is nonempty, fail. */
- if (f->rpos < f->buf) {
- FUNLOCK(f);
- return WEOF;
- }
-
- /* Put character back into the buffer */