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Date:      Tue, 25 Mar 1997 17:38:48 -0700 (MST)
From:      Terry Lambert <terry@lambert.org>
To:        bde@zeta.org.au (Bruce Evans)
Cc:        bde@zeta.org.au, rb@gid.co.uk, freebsd-current@FreeBSD.ORG, joerg_wunsch@uriah.heep.sax.de, terry@lambert.org
Subject:   Re: 2.2R (src 2.2 211): <ctrl><alt><del> == dialing
Message-ID:  <199703260038.RAA26494@phaeton.artisoft.com>
In-Reply-To: <199703252333.KAA16629@godzilla.zeta.org.au> from "Bruce Evans" at Mar 26, 97 10:33:32 am

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> >>The slattach daemon has a controlling tty...
> >
> >Only until it calls daemon() immediately after cracking its args.
> 
> No.  It acquires a controlling tty a few lines after it becomes a
> daemon, at least in the redial case (I think the !redial case is
> still broken - it does a null redial instead of aborting like the
> documentation for the -l option says it does).

This means it should get a SIGHUP on on-to-off DCD transistion if
-CLOCAL is set.

Does it mean it should get SIGHUP when the tty is revoked? ...I don't
think so, actually.

There is a distingtion to be drawn between acquiring a controlling
tty, and becoming a process group leader.

Part of the problem here is how daemon(3) is supposed to work.  It
does not say that the process becomes a group or session leader,
actually (this may just be a deficit in the man page; if so, it
is arguable that the process should become a deamon by performing the
explicit acts to become a daemon instead of making the library call
with the process/session leadership side effects).

You *could* argue, on this basis, that slattach is doing the wrong thing,
and that's what's leaving it open to getting a SIGHUP when it should
not be getting on.

On the other hand, I believe other programs which call daemon(3) and
do not reacquire a controlling tty also get the SIGHUP on shutdown,
so no matter what, there is something rotten in Denmark...


					Regards,
					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.



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