From: Karel Zak <kzak@redhat.com>
To: Stef Walter <stefw@redhat.com>
Cc: util-linux@vger.kernel.org
Subject: Re: [PATCH] agetty: Reprompt and reprint /etc/issue if we receive SIGUSR1
Date: Tue, 15 Jul 2014 09:51:40 +0200 [thread overview]
Message-ID: <20140715075140.GO30288@x2.net.home> (raw)
In-Reply-To: <53C4D9DB.10703@redhat.com>
On Tue, Jul 15, 2014 at 09:35:55AM +0200, Stef Walter wrote:
> On 14.07.2014 15:37, Karel Zak wrote:
> > On Mon, Jul 07, 2014 at 09:31:24AM +0200, Stef Walter wrote:
> >> Several of the /etc/issue escape codes such as \4 and \S depend on
> >> variable data which can change after the agetty prompt is displayed.
> >> This can cause stale data to be displayed when a user looks at a VT,
> >> especially in cases of DHCP racing with system start up.
> >>
> >> This commit allows agetty to react a SIGUSR1 signal by reprinting
> >> its prompt including the reprocessing of /etc/issue.
> >>
> >> We never want this to occur once the user has started typing a
> >> user name. So we detect when the user starts typing, after which
> >> no further reprompting occurs even if SIGUSR1 is received.
> >
> > Good idea, interesting implementation, but it's too late for v2.25.
> > I'm going to apply the patch to the git tree after v2.25 release.
>
> Nice. Thanks.
I have never seen the idea with VMIN and TIOCSTI ioctl, that's
interesting thing.
> Lennart discovered an issue with this ...
>
> That the exec'ing the login process might race with the SIGUSR1 signal.
> The fix here would be to signal(SIGUSR1, SIG_IGN) before exec'ing, does
> that sound appropriate? I can post a new patch.
>
> By the way, more information about this use case here:
> https://bugzilla.redhat.com/show_bug.cgi?id=1110763
Yes, I read it yesterday evening. Lennart is right about the race.
Karel
--
Karel Zak <kzak@redhat.com>
http://karelzak.blogspot.com
next prev parent reply other threads:[~2014-07-15 7:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-07 7:31 [PATCH] agetty: Reprompt and reprint /etc/issue if we receive SIGUSR1 Stef Walter
2014-07-14 13:37 ` Karel Zak
2014-07-15 7:35 ` Stef Walter
2014-07-15 7:51 ` Karel Zak [this message]
2014-07-15 7:47 ` Karel Zak
2014-07-15 7:57 ` Stef Walter
2014-07-15 9:19 ` Karel Zak
2014-07-15 12:40 ` Stef Walter
2014-07-15 16:12 ` Stef Walter
2014-07-16 10:02 ` Karel Zak
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