/*--------
Date: Wed, 14 Jan 87 16:14:00 pst
From: sd%chem@sdcsvax.ucsd.edu (Steve Dempsey)
Message-Id: <8701150014.AA22673@sdchemf.chem.ucsd.arpa>
To: info-iris@sumex-aim.stanford.edu
Subject: tty input bugs in the 3.5 kernel

I've found a couple of bugs with tty input in the 3.5 kernel.
We are running the standard TCP/IP kernel on a 2400 Turbo (ser. #547).
I've included a couple of simple test programs which demonstrate the
problems.  These programs run correctly on a VAX 750 (4.3BSD) and
a Celerity 1260D (4.2BSD).  I've reported these problems to the HOTLINE.
The console, a direct connect terminal, and remote network terminals
all exhibit the same behavior.
--------*/

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/*
* This test monitors the count returned by the FIONREAD ioctl.
* Note that the count changes as you enter or delete characters.
* This seems to indicate that the count is for the RAW input queue.
*
* Previous SGI systems (and all other UNIX based machines we have)
* return the count for the CANONICAL input queue ****!
*
* The problem this creates occurs whe you are polling for tty input
* and the user enters a line containing only a newline character.
* The count for the raw queue goes to 1, but since the newline is the
* end-of-line character it is moved almost immediately from the raw queue
* to the canonical queue, so the count for the raw queue goes back to zero.
* If the ioctl does not occur during the very short period while the newline
* is still in the raw queue you will never know the newline was entered.
*/

#include <stdio.h>
#include <sgtty.h>
main()
	{
	int	lastcnt, ccnt;
	int	readline();

	lastcnt = 1000000;
	while(1)
	    {
	    ioctl(0, FIONREAD, &ccnt);
	    if(ccnt != lastcnt)
		{
		printf("ioctl reports %d chars in input.\n", ccnt);
		lastcnt = ccnt;
		}
	    sleep(1);
	    }
	}
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/*
* This test shows the incorrect behavior of a read of tty input.
* While the program is sleeping enter multiple lines of text.
* When the read is executed all lines are read, not just the first one.
*/
#include <stdio.h>
main()
	{
	int	nc;
	char	lbuf[100];

	sleep(10);
	nc = read(0, lbuf, sizeof lbuf);
	lbuf[nc] = 0;
	printf("nc=%d, read=%s", nc, lbuf);
	}
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