#!/bin/bash
# Bash required because /usr/share/debconf/confmodule uses "local" (#252094)

set -e

. /usr/share/debconf/confmodule

MYNAME=resolvconf.postinst
report() { echo "${MYNAME}: $*" ; }
report_err() { report "Error: $*" >&2 ; }
report_info() { report "Info: $*" >&2 ; }

### Create /etc/resolvconf/run ###
case "$1" in
configure|reconfigure)
	# Unfortunately we can't keep state files in /var/run/ because 
	# resolvconf, as it must, initializes before networking does and
	# /var/ can be on the network.
	#
	# Only use an existing symlink if it is canonicalizable
	if [ -L /etc/resolvconf/run ] ; then
		RUN_CANONICALPATH="$(readlink -f /etc/resolvconf/run || :)"
		if [ -z "$RUN_CANONICALPATH" ] ; then
			report_err "Deleting /etc/resolvconf/run symlink whose canonical path could not be determined"
			rm -f /etc/resolvconf/run
		elif \
			[ "$RUN_CANONICALPATH" = "/dev/shm/resolvconf" ] \
			&& [ -d /lib/init/rw ] \
			&& [ -w /lib/init/rw ] \
			&& [ -r /proc/mounts ] \
			&& grep -qs "^tmpfs[[:space:]]\+/lib/init/rw[[:space:]]\+tmpfs[[:space:]]\+\([^[:space:]]\+,\)\?rw" /proc/mounts \
			&& { [ -d /lib/init/rw/resolvconf ] || mkdir -v /lib/init/rw/resolvconf ; } \
			&& { [ -d /lib/init/rw/resolvconf/interface ] || mkdir -v /lib/init/rw/resolvconf/interface ; }
		then
			report_info "Migrating /dev/shm/resolvconf to /lib/init/rw/resolvconf"
			F="$(echo /dev/shm/resolvconf/*)"
			[ "$F" ] && [ "$F" != '/dev/shm/resolvconf/*' ] && cp -a /dev/shm/resolvconf/* /lib/init/rw/resolvconf
			ln -sf /lib/init/rw/resolvconf /etc/resolvconf/run
		fi
	fi
	# Delete it if it isn't a directory or a link to one
	if [ -e /etc/resolvconf/run ] && [ ! -d /etc/resolvconf/run ] ; then
		report_err "Deleting /etc/resolvconf/run which isn't a directory"
		rm -f /etc/resolvconf/run
	fi
	# Now /etc/resolvconf/run is either
	# * a directory, or
	# * a symlink to a directory, or
	# * a nonexistent (if you'll pardon the expression), or
	# * a dangling but canonicalizable symlink
	if [ -d /etc/resolvconf/run ] ; then
		# It's a directory or a symlink to one
		[ -d /etc/resolvconf/run/interface ] || mkdir -v /etc/resolvconf/run/interface
	elif [ -L /etc/resolvconf/run ] ; then
		# It's a dangling but canonicalizable symlink
		mkdir -v "$RUN_CANONICALPATH"
		mkdir -v "${RUN_CANONICALPATH}/interface"
	else
		# It's a nonexistent
		# Use /lib/init/rw if possible
		if \
			[ -d /lib/init/rw ] \
			&& [ -w /lib/init/rw ] \
			&& [ -r /proc/mounts ] \
			&& grep -qs "^tmpfs[[:space:]]\+/lib/init/rw[[:space:]]\+tmpfs[[:space:]]\+\([^[:space:]]\+,\)\?rw" /proc/mounts \
			&& { [ -d /lib/init/rw/resolvconf ] || mkdir -v /lib/init/rw/resolvconf ; } \
			&& { [ -d /lib/init/rw/resolvconf/interface ] || mkdir -v /lib/init/rw/resolvconf/interface ; }
		then
			ln -s /lib/init/rw/resolvconf /etc/resolvconf/run
		else
			mkdir -v /etc/resolvconf/run
			mkdir -v /etc/resolvconf/run/interface
		fi
	fi
	;;
# *)
	# In other modes we don't need to do anything
	# because we didn't take any action in the prerm
esac


case "$1" in
configure|reconfigure)
	# Deleting the old runlevel config is unavoidable
	# because there is currently no way in Debian
	# to update the config iff it is still the factory default
	update-rc.d -f resolvconf remove > /dev/null 2>&1
	;;
esac

# We use dh_installinit with --no-start
#DEBHELPER#

### Link tail to original if appropriate ###
TIME_TO_CHANGE_TAIL_LINK=no
case "$1" in
configure|reconfigure)
	TIME_TO_CHANGE_TAIL_LINK=yes
	;;
# *)
	# In other modes we don't need to do anything
	# because we didn't take any action in the prerm
esac

if [ "$TIME_TO_CHANGE_TAIL_LINK" = yes ] ; then
	if [ ! -e /etc/resolvconf/resolv.conf.d/tail ] ; then
		db_get resolvconf/link-tail-to-original
		if [ "$RET" = "true" ] ; then
			ln -nsf original /etc/resolvconf/resolv.conf.d/tail
		else
			: > /etc/resolvconf/resolv.conf.d/tail
		fi
	fi
fi

### Linkify /etc/resolv.conf if appropriate ###
TIME_TO_CHANGE_LINKIFICATION=no
case "$1" in
configure|reconfigure)
	TIME_TO_CHANGE_LINKIFICATION=yes
	;;
# *)
	# In other modes we don't need to do anything
	# because we didn't take any action in the prerm
esac

if [ "$TIME_TO_CHANGE_LINKIFICATION" = yes ] ; then
	db_get resolvconf/linkify-resolvconf
	if [ "$RET" = "true" ] ; then
		# Back up
		if \
			[ -f /etc/resolv.conf ] \
			&& { \
				[ ! -L /etc/resolv.conf ] \
				|| [ ! "$(readlink /etc/resolv.conf)" = "/etc/resolvconf/run/resolv.conf" ] ; \
			}
		then
			if [ ! -e /etc/resolvconf/resolv.conf.d/original ] ; then
				cp -a /etc/resolv.conf /etc/resolvconf/resolv.conf.d/original
			else
				cp -a /etc/resolv.conf /etc/resolv.conf.dpkg-old
			fi
			# Before creating the link, make sure that the original file is
			# at the target of the link.  /sbin/resolvconf will overwrite
			# this when it runs, of course.
			if [ ! -e /etc/resolvconf/run/resolv.conf ] ; then
				cp -a /etc/resolv.conf /etc/resolvconf/run/resolv.conf
			fi
		fi

		# Create the link
		ln -nsf /etc/resolvconf/run/resolv.conf /etc/resolv.conf

	fi
fi
								
db_stop

### Enable updates ###
if [ -x "/etc/init.d/resolvconf" ] ; then
	if which invoke-rc.d >/dev/null 2>&1 ; then
		invoke-rc.d resolvconf enable-updates || :
	else
		/etc/init.d/resolvconf enable-updates
	fi
fi