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From: Pavel Machek <pavel@denx.de>
To: Arseny Maslennikov <ar@cs.msu.ru>
Cc: Pavel Machek <pavel@denx.de>,
	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: Wed, 12 Jun 2019 11:41:08 +0200	[thread overview]
Message-ID: <20190612094108.GA11439@amd> (raw)
In-Reply-To: <20190609205610.GB3736@cello>

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Hi!

> > > 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
> 
> As of now, that application will indeed receive a signal that is
> guaranteed to be ignored by default.
> 
> This is similar to SIGWINCH, which is default-ignored as well: if the
> terminal width/height changes (like when a terminal emulator window is
> resized), its foreground pgrp gets a surprise signal as well, and the
> processes that don't care about WINCH (and thus have default
> disposition) do not get confused.
> E.g. 'strace cat' demonstrates this quite clearly.

Ok, so this should be safe as long as noone listens for SIGPWR. So
... I guess we are ok :-).
								Pavel


-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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  parent reply	other threads:[~2019-06-12  9:41 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
2019-06-09 20:56       ` Arseny Maslennikov
2019-06-10 21:18         ` Rob Landley
2019-06-12  9:41         ` Pavel Machek [this message]
2019-06-10 21:06 ` Rob Landley

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