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Date: Tue, 10 Oct 1995 08:56:12 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199510092256.IAA27162@godzilla.zeta.org.au>
To: bde@zeta.org.au, pst@cisco.com, stu@cisco.com
Subject: Re: FleeBSD and XNTPD
Cc: hackers@freebsd.org
Sender: owner-hackers@freebsd.org
Precedence: bulk

>>FSETOWN has never worked "right" for ttys in FreeBSD releases.  It only
>>works for controlling terminals that are associated with the session of
>>the calling process.  Using it may interfere with normal controlling

>Agreed but doesn't this apply to terminal devices to which there is already
>attached a controlling terminal ?  In this instance there is nothing
>hanging on the terminal device at all - ie no login shell or similar.
>Shouldn't the
>rejection of the attempt be made iff there is already a process marked as the
>controlling process ?

There must be a controlling process for tcsetpgrp() to work.  F_SETOWN
shouldn't interfere with tcsetpgrp().  (I'd like F_SETOWN to be completely
independent of the controlling terminal and its process[group].  Since
F_SETOWN applies to file descriptors, I would expect the process[group]
to be per-fd.  Is that too general?)

>See above - how would a process get itself marked as the recipient of the
>signal without being able to use F_SETMODE or TICGSPGP (both of which
>should map to the same thing) ?

It can't be done that way.  Under FreeBSD, the following all seems to be
necessary:

	setsid();
	ioctl(fd, TIOCSCTTY);
	fcntl(fd, F_SETOWN, getpid());
	fl = fcntl(fd, F_GETFL);
	fcntl(fd, F_SETFL, fl | O_ASYNC);

Plus error checking and setting up the signal handler of course.

Bruce