Support DISCARD (^O)

Slawa Olhovchenkov
2013-12-26T14:09:46Z

On Tue, Dec 17, 2013 at 10:18:16PM +0100, Eivind Evensen wrote:

> Hello.
>
> I don't know if there is any particular reason that support for
DISCARD/^O
> was not included in the tty rewrite that happened from FreeBSD 7 to 8,
> but in case anybody else wants it, here's a diff functioning mostly
> like in 7, except output isn't switched back on automatically on input.
>
> Diff is against FreeBSD 8, however, last time I checked I didn't see
> much difference in the newer versions.
>
> Regards, Eivind

Nice! Very nice feature, need to commit in the tree.

> diff -r 91820d9948e0 -r 13f40d577646 sys/kern/tty_ttydisc.c
> --- a/sys/kern/tty_ttydisc.c	Fri Feb 22 09:45:32 2013 +0100
> +++ b/sys/kern/tty_ttydisc.c	Tue Dec 17 23:03:17 2013 +0100
> @@ -448,6 +448,9 @@
>  	if (tp->t_flags & TF_ZOMBIE)
>  		return (EIO);
>
> +	if (tp->t_termios.c_lflag & FLUSHO)
> +		return (0);
> +
>  	/*
>  	 * We don't need to check whether the process is the foreground
>  	 * process group or if we have a carrier. This is already done
> @@ -881,6 +884,14 @@
>
>  	/* Special control characters that are implementation dependent. */
>  	if (CMP_FLAG(l, IEXTEN)) {
> +		/* Discard (^O) */
> +		if (CMP_CC(VDISCARD, c)) {
> +			if (!(tp->t_termios.c_lflag & FLUSHO))
> +				ttyoutq_write_nofrag(&tp->t_outq, "^O", 2);
> +			tp->t_termios.c_lflag ^= FLUSHO;
> +			return(0);
> +		}
> +
>  		/* Accept the next character as literal. */
>  		if (CMP_CC(VLNEXT, c)) {
>  			if (CMP_FLAG(l, ECHO)) {
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