[net.bugs.usg] Bug in no-delay read in System III

guy@rlgvax.UUCP (07/10/83)

To quote from something sent out with (Warren Montgomery's?) EMACS:

	EMACS has been changed to take advantage of no-delay tty/io...
	IN UNIX 3.0 and UNIX 3.0.1 (System III is 3.0.1 - gh) as released,
	the NDELAY option on I/O does not work (read always returns 0).
	...On our system, we fixed this bug by changing lines 488-500 of
	/usr/src/uts/pdp11/io/tty.c

	FROM
		if (tq->c_cc == 0)
			if (u.u_fmode&FNDELAY)
				return;

	TO

		if (tq->t_cc == 0)
			if (u.u_fmode&FNDELAY && tp->t_rawq.c_cc == 0)
				return;

	Guy Harris
	Computer Consoles, Inc.
	Office Systems Group
	{seismo,mcnc,we13,brl-bmd,allegra}!rlgvax!guy