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From: brandon@tdi2.UUCP
Newsgroups: comp.sources.wanted,comp.unix.wizards,comp.unix.questions
Subject: Re: UUCP Port Turnaround
Message-ID: <135@tdi2.UUCP>
Date: Thu, 19-Feb-87 19:40:55 EST
Article-I.D.: tdi2.135
Posted: Thu Feb 19 19:40:55 1987
Date-Received: Sat, 21-Feb-87 04:38:48 EST
References: <171@ndmath.UUCP> <4090@nsc.nsc.com> <166@piaget.UUCP> <43099@beno.seismo.CSS.GOV> <2388@homxb.UUCP> <13355@sun.uucp>
Reply-To: brandon@tdi2.UUCP (Brandon Allbery)
Followup-To: comp.sources.wanted
Organization: Tridelta Industries, Inc., Mentor, OH
Lines: 101
Xref: utgpu comp.sources.wanted:594 comp.unix.wizards:1068 comp.unix.questions:1125

Quoted from <13355@sun.uucp> ["Re: UUCP Port Turnaround"], by guy%gorodish@Sun.COM (Guy Harris)...
+---------------
| >> You should try the kernel hack on a decent system before dismissing it.
| >
| >I guess it's just the Berkeley philosophy to do things in the kernel
| >whenever possible, even when it's not necessary.
| 
| Oh, good grief!
| 
| Putting it in the kernel (and it's *not* a lot of code, believe me -
| probably less than 1KB, and probably less than the code you have to
| add to the system if you don't do it in the kernel!)  means that, as
| Rick pointed out, you *don't* have to modify "getty" or "uucp" or
| anybody else that wants to dial out.
+---------------

I'm running System V.2 (yes, *that*).  The inittab and special init states
a, b, c make life a lot easier.

--------------
uugetty.sh
--------------
tty="`echo $1 | sed 's:/dev/::'`"
while test -f /usr/spool/uucp/uulk."$tty" -o -f /usr/spool/uucp/LCK.."$tty"; do
	sleep 300
done
exec /etc/getty "$@"

--------------
uulock.sh
--------------
:

usage="usage: $0 [-lu] tty"
job=lock
exec > /dev/syscon 2>&1
case "$1" in
-l)	job=lock
	shift
	;;
-u)	job=unlock
	shift
	;;
esac
case "$#$1" in
1*)	;;
*)	echo "$usage"
	exit 1
esac
who -a > /tmp/uul$$
case "$job" in
unlock)	grep "^uugetty    /dev/$1 " /tmp/uul$$ > /dev/null 2>&1 || {
		echo "$0: device /dev/$1 is unlocked or nonexistent"
		/bin/rm /tmp/uul$$
		exit 3
	}
	;;
*)	grep "^LOGIN      /dev/$1 " /tmp/uul$$ > /dev/null 2>&1 || {
		echo "$0: device /dev/$1 is busy or nonexistent"
		/bin/rm /tmp/uul$$
		exit 2
	}
esac
case "$job" in
unlock)	/usr/lib/uucp/hup $1
	rm -f /usr/spool/uucp/uulk.$1
	;;
*)	touch /usr/spool/uucp/uulk.1
	set -- `grep "^LOGIN      /dev/$1 " /tmp/uul$$`
	kill -9 $7
esac
rm -f /tmp/uul$$

-------------
NOTE:  /usr/lib/uucp/hup simply sends an ATZ to the modem to make it happy.
A smarter UUCP or getty or etc. could do this as well.

-------------
/etc/inittab (partial)
-------------
22:2:respawn:/etc/uugetty /dev/tty22 M1200 #Remote Dial-In
ul:b:wait:/etc/uulock -l tty22 # lock it
uu:c:wait:/etc/uulock -u tty22 # unlock it

The only oddness is in killing the existing getty; if there is none, the
program knows it's either locked already or in use.

This is probably adaptable to BSD, given that BSD has a ttys file that lets
you say what getty to run on a port.  The telinit b/c stuff from System V is
just handy; it's by no means necessary.  However, you'll have to change the
utmp-checking code in uulock.sh to check processes instead.

++Brandon
-- 
``for is he not of the Children of Luthien?  Never shall that line fail, though
the years may lengthen beyond count.''  --J. R. R. Tolkien

Brandon S. Allbery	           UUCP: cbatt!cwruecmp!ncoast!tdi2!brandon
Tridelta Industries, Inc.         CSNET: ncoast!allbery@Case
7350 Corporate Blvd.	       INTERNET: ncoast!allbery%Case.CSNET@relay.CS.NET
Mentor, Ohio 44060		  PHONE: +1 216 255 1080 (home) +1 216 974 9210