Bug#380119: [Resolvconf-devel] Bug#380119: resolvconf: patch to support dnscache instances managed by runit instead of by daemontools

[Daniel Kahn Gillmor]

On July 28, jdthood at yahoo.co.uk said:

 > Can you please send the new version of the script (rather than the diff)?

Sure thing.  It's attached below.

Thanks for the speedy reply,

	--dkg

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#!/bin/sh
#
# /etc/resolvconf/update.d/dnscache
#
# Script to update every forwarding djbdns dnscache instance running
# on the local machine
#
# this script sets up every FORWARDONLY dnscache managed by either
# daemontools or runit on this machine to use the dynamically-offered
# nameservers for the default '@'
# 
# Assumption: On entry, PWD contains the resolv.conf-type files
#
# If no nameservers are offered, we ask the dnscache instances to fall
# back to the root nameservers listed in /etc/dnsroots.global
#
# Licensed under the GNU GPL.  See /usr/share/doc/resolvconf/copyright.
#
# Written by Daniel Kahn Gillmor <dkg-debian.org at fifthhorseman.net>
# based on other scripts by Thomas Hood

set -e
PATH=/sbin:/bin:/usr/sbin:/usr/bin

[ -x /usr/bin/dnscache ] || exit 0
[ -x /lib/resolvconf/list-records ] || exit 1


ETC=/etc
ETCRESOLVCONF="${ETC}/resolvconf"
TMPFILE="${ETCRESOLVCONF}/run/dnscache_new.$$"
DEFAULTROOTS="${ETC}/dnsroots.global"


CACHES=""

# which directories do we scan?
# /var/lib/svscan: daemontools, built "the debian way" (LFS-compliant)
# /service: daemontools, built "the djb way"
# /var/service: runit

for SERVICEDIR in /var/lib/svscan /service /var/service; do
# We'll only manage caches actually managed by daemontools or runit.
    if [ -d $SERVICEDIR ] && [ -z "`ls $SERVICEDIR`" ]; then
	for SVC in $SERVICEDIR/* ; do
	    if  [ -d $SVC/ ] && [ -f $SVC/run ] && \
		(grep -q dnscache $SVC/run) && \
		[ -d $SVC/root ] && \
		[ -d $SVC/root/servers ] && \
		[ -d $SVC/root/ip ] && \
		[ -s $SVC/env/FORWARDONLY ] ; then
		CACHES="$SVC $CACHES"
	    fi
	done
    fi
done



# Stores arguments (minus duplicates) in RSLT, separated by spaces
# Doesn't work properly if an argument itself contain whitespace
uniquify()
{
	RSLT=""
	while [ "$1" ] ; do
		for E in $RSLT ; do
			[ "$1" = "$E" ] && { shift ; continue 2 ; }
		done
		RSLT="${RSLT:+$RSLT }$1"
		shift
	done
}

RSLVCNFFILES="$(/lib/resolvconf/list-records)"

### Compile list of nameservers ###
NMSRVRS=""
if [ "$RSLVCNFFILES" ] ; then
	uniquify $(sed -n 's/^[[:space:]]*nameserver[[:space:]]\+//p' $RSLVCNFFILES)
	NMSRVRS="$RSLT"
fi


# If no nameservers were present, use the default root nameservers
# provided by the djbdns package:
if [ -z "$NMSRVRS" ] && [ -e "$DEFAULTROOTS" ] ; then
	cp "$DEFAULTROOTS" "$TMPFILE"
else
	: > "$TMPFILE"
	for N in $NMSRVRS ; do
		echo "$N" >> "$TMPFILE"
	done
fi

# svc is the daemontools service controller
SVC_CMD="$(which svc)" || :
[ ! "$SVC_CMD" ] && [ -x /command/svc ] && SVC_CMD=/command/svc

# sv is the runit service controller
SV_CMD="$(which sv)" || :


for CACHE in $CACHES ; do
	cp "$TMPFILE" "$CACHE/root/servers/@"
	# Restart the cache if it's already running:
	if [ `dirname "$CACHE"`x == '/var/servicex' ]; then
	    # this is managed by runit
	    [ "SV_CMD" ] && "SV_CMD" t "$CACHE"
	else
	    # this is probably managed by daemontools
	    [ "$SVC_CMD" ] && $SVC_CMD -t "$CACHE"
	fi
done

rm -f "$TMPFILE"