live-build/scripts/build/chroot_resolv

#!/bin/sh

## live-build(7) - System Build Scripts
## Copyright (C) 2016-2020 The Debian Live team
## Copyright (C) 2006-2015 Daniel Baumann <mail@daniel-baumann.ch>
##
## This program comes with ABSOLUTELY NO WARRANTY; for details see COPYING.
## This is free software, and you are welcome to redistribute it
## under certain conditions; see COPYING for details.


set -e

# Including common functions
[ -e "${LIVE_BUILD}/scripts/build.sh" ] && . "${LIVE_BUILD}/scripts/build.sh" || . /usr/lib/live/build.sh

# Setting static variables
DESCRIPTION="Manage /etc/resolv.conf"
USAGE="${PROGRAM} {install|remove} [--force]"

# Processing arguments and configuration files
Init_config_data "${@}"

# Requiring stage file
Require_stagefile config bootstrap

case "${1}" in
	install)
		Echo_message "Configuring file /etc/resolv.conf"

		# Checking stage file
		Check_stagefile

		# Acquire lock file
		Acquire_lockfile

		if [ -e chroot/etc/resolv.conf ]
		then
			# Save resolv file or symlink
			mv chroot/etc/resolv.conf chroot/etc/resolv.conf.orig

			# Also truncate it, otherwise we'll end up with the one
			# created by debootstrap in the final image.
			#
			# If you want to have a custom resolv.conf, please
			# overwrite it with normal local_includes mechanism.
			Truncate chroot/etc/resolv.conf.orig
		elif [ -L chroot/etc/resolv.conf ]
		then
			# Move resolv.conf aside if it's a symlink (likely resolvconf)
			mv chroot/etc/resolv.conf chroot/etc/resolv.conf.orig
		fi

		if [ -f /etc/resolv.conf ]
		then
			# Copy resolv file
			cp /etc/resolv.conf chroot/etc/resolv.conf
		fi

		# Creating stage file
		Create_stagefile
		;;

	remove)
		Echo_message "Deconfiguring file /etc/resolv.conf"

		# Acquire lock file
		Acquire_lockfile

		if [ -e config/includes.chroot/etc/resolv.conf ]
		then
			# Copying local resolv.conf
			cp -a config/includes.chroot/etc/resolv.conf chroot/etc/resolv.conf
			rm -f chroot/etc/resolv.conf.orig
		elif [ -e chroot/etc/resolv.conf.orig ] || [ -L chroot/etc/resolv.conf.orig ]
		then
			# Restoring resolv file or symlink
			mv chroot/etc/resolv.conf.orig chroot/etc/resolv.conf
		else
			# Truncating resolv file
			Truncate chroot/etc/resolv.conf
		fi

		# Clean up resolvconf's pollution
		if [ -e chroot/etc/resolvconf/resolv.conf.d ]
		then
			rm -f chroot/etc/resolvconf/resolv.conf.d/original
			rm -f chroot/etc/resolvconf/resolv.conf.d/tail
		fi

		# Removing stage file
		Remove_stagefile
		;;

	*)
		Usage
		;;
esac