linux-kernel - Re: tty: ctrl-c not always echoed, especially under load

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 7 Aug 2008 20:37:16 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Joe Peterson <joe@...rush.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: tty: ctrl-c not always echoed, especially under load

On Wed, 06 Aug 2008 14:17:29 -0600
Joe Peterson <joe@...rush.com> wrote:

> Alan Cox wrote:
> > If the output buffer is full then echoed characters/^C etc will vanish the
> > way n_tty implements its buffering internally. It's always worked that
> > way.
> 
> One more observation:
> 
> In Linux, try this:
> 
> # cat > foo
> hi^Sthere^Q
> ^D
> 
> (in other words, during the cat into "foo", type "hi", hit ^S, then type
> "there", then hit ^Q, then, on the next line, ^D to end the file)
> 
> Note that the "there" does not appear after hitting ^Q, but it does
> appear in the file.  So the characters were accepted, but they were not
> echoed (not even saved for echo when the terminal is restarted).
> 
> This behavior differs from that of FreeBSD (just tried it for fun -
> haven't tried other Unix's yet).  I have noticed other times that the
> echo seems to get lost while the tty is stopped.  Not sure if all this
> is related, but something seems amiss.  Thoughts?

It should certainly occur if the output buffer is full but that shouldn't
be the case for a few bytes. Agreed the current behaviour is unexpected
and less than desirable so hack away.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/