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Date: Sat, 5 Jul 2014 12:34:16 +0200
From: Eivind Nicolay Evensen <eivinde@terraplane.org>
To: freebsd-stable@freebsd.org
Subject: Re: Support DISCARD (^O)
Message-ID: <20140705103415.GA55807@klump.hjerdalen.lokalnett>
References: <20131217211816.GA41797@klump.hjerdalen.lokalnett>
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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.
Here's a diff against FreeBSD 10. It seems to work fine there too.
diff -r 59ad9c4b7916 -r 6e500f4552b4 sys/kern/tty_ttydisc.c
--- a/sys/kern/tty_ttydisc.c Fri Jul 04 17:27:59 2014 +0200
+++ b/sys/kern/tty_ttydisc.c Fri Jul 04 17:29:29 2014 +0200
@@ -464,6 +464,9 @@
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
@@ -896,6 +899,14 @@
/* 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)) {