From: Pavel Machek <pavel@denx.de>
To: Arseny Maslennikov <ar@cs.msu.ru>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
"Vladimir D . Seleznev" <vseleznv@altlinux.org>
Subject: Re: [PATCH 0/7] TTY Keyboard Status Request
Date: Sun, 9 Jun 2019 21:51:32 +0200 [thread overview]
Message-ID: <20190609195132.GA1430@amd> (raw)
In-Reply-To: <20190609194013.GA3736@cello>
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Hi!
> > > This patch series introduces TTY keyboard status request, a feature of
> > > the n_tty line discipline that reserves a character in struct termios
> > > (^T by default) and reacts to it by printing a short informational line
> > > to the terminal and sending a Unix signal to the tty's foreground
> > > process group. The processes may, in response to the signal, output a
> > > textual description of what they're doing.
> > >
> > > The feature has been present in a similar form at least in
> > > Free/Open/NetBSD; it would be nice to have something like this in Linux
> > > as well. There is an LKML thread[1] where users have previously
> > > expressed the rationale for this.
> > >
> > > The current implementation does not break existing kernel API in any
> > > way, since, fortunately, all the architectures supported by the kernel
> > > happen to have at least 1 free byte in the termios control character
> > > array.
> >
> > I like the idea... I was often wondering "how long will this dd take". (And in
> > case of dd, SIGUSR1 does the job).
> >
> > I assume this will off by default, so that applications using ^T today will not
> > get surprise signals?
>
> If any of isig, icanon and iexten is disabled on the tty, the signal is
> not sent.
As expected.
> Any application that wants to handle raw terminal input events itself,
> e.g. vim, mutt, libreadline, anything ncurses-based, etc., has to turn
> off the tty's cooked mode, i.e. at least icanon. This means those
> applications are unaffected.
Agreed, those are unaffected.
But if I have an application doing read() from console (without
manipulating tty), am I going to get surprise signal when user types
^T?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2019-06-09 19:51 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-05 8:18 [PATCH 0/7] TTY Keyboard Status Request Arseny Maslennikov
2019-06-05 8:19 ` [PATCH 1/7] signal.h: Define SIGINFO on all architectures Arseny Maslennikov
2019-06-10 21:10 ` Rob Landley
2019-06-11 20:36 ` Eric W. Biederman
2019-06-11 22:38 ` Arseny Maslennikov
2019-06-05 8:19 ` [PATCH 2/7] tty: termios: Reserve space for VSTATUS in .c_cc Arseny Maslennikov
2019-06-05 8:19 ` [PATCH 3/7] n_tty: Send SIGINFO to fg pgrp on status request character Arseny Maslennikov
2019-06-05 8:19 ` [PATCH 4/7] linux/signal.h: Ignore SIGINFO by default in new tasks Arseny Maslennikov
2019-06-05 8:19 ` [PATCH 5/7] tty: Add NOKERNINFO lflag to termios Arseny Maslennikov
2019-06-05 8:19 ` [PATCH 6/7] n_tty: ->ops->write: Cut core logic out to a separate function Arseny Maslennikov
2019-06-05 8:19 ` [PATCH 7/7] n_tty: Provide an informational line on VSTATUS receipt Arseny Maslennikov
2019-06-09 17:41 ` [PATCH 0/7] TTY Keyboard Status Request Pavel Machek
2019-06-09 19:40 ` Arseny Maslennikov
2019-06-09 19:51 ` Pavel Machek [this message]
2019-06-09 20:56 ` Arseny Maslennikov
2019-06-10 21:18 ` Rob Landley
2019-06-12 9:41 ` Pavel Machek
2019-06-10 21:06 ` Rob Landley
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