int opost (unsigned char c, struct tty_struct * tty);
Perform OPOST processing. Returns -1 when the output device is full and the character must be retried. Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't relevant in the world today. If you ever need them, add them here.
Called from both the receive and transmit sides and can be called re-entrantly. Relies on lock_kernel still.