Date: Mon, 2 Dec 1996 15:02:24 +1100 From: davidn@sdev.usn.blaze.net.au (David Nugent) To: freebsd-hackers@FreeBSD.ORG Subject: Logging ttys off Message-ID: <Mutt.19961202150224.davidn@sdev>
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I'm looking for a "foolproof" way of logging out lines that
are in use. The only real information available at the time I
need to do this is the user's utmp entry.
The problems I'm having are:
- I don't have the process id of the process group leader
(unlike SYSV, unforuntately BSD's utmp doesn't provide this)
- the serial port may not be accessible, even by root, if
the port is in ppp/slip mode.
- even if the serial port can be opened, setting the input/
output speeds to B0 does not reliably kill the line
(is this an error? should it?). It seems to work on
serial lines without clocal set, but not otherwise - I
would have expected a hangup on the port regardless (seems
to work reliably in other UNIXes I've worked with in the
past).
So, I'm back to looking for the pid of the process group
leader so I can kill it with SIGTERM/SIGKILL.
One option that occurs to me is to look at /proc (is the proc
filesystem more or less mandatory now?), and attempting to
find processes owned by the user, and building a tree of
processes to find out which ones were initiated from a
particular login (with the advantage of being able to
optionally sweep out background processes that would not
otherwise die with the process leader). Since I haven't yet
looked at this in depth, I'm not even sure if this is a viable
solution. I haven't even considered digging this info out of
/dev/kmem yet, and since that style of solution seems to be
depreciated in any case, that's one path I'd definitely prefer
to avoid, especially if this is likely to lead to kernel
version dependancies (like ps).
Since I'm sure to be reinventing the wheel in doing this, has
anyone else ever needed to do something similar? And *please*
don't suggest spawning ps and examining its output. :-) Any
other suggestions welcome. I did look at source for a couple
of idle logout daemons, but both of them used the "set port
speed to 0" method, but as I said, this doesn't work reliably
enough, nor can I restrict what I'm working on to use with
dialup lines only.
Regards,
David Nugent, Unique Computing Pty Ltd - Melbourne, Australia
Voice +61-3-9791-9547 Data/BBS +61-3-9792-3507 3:632/348@fidonet
davidn@blaze.net.au http://www.blaze.net.au/~davidn
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