#!/bin/bash

####################################################################################
### INSTRUCTIONS AT https://github.com/lesderid/digitalocean-debian-to-arch/     ###
####################################################################################

run_from_file() {
	local f t
	for f in /dev/fd/*; do
		[ -h $f ] || continue
		[ $f -ef "$0" ] && return
	done
	t=$(mktemp)
	cat > $t
	if [ "$(head -n 1 $t)" = '#!/bin/bash' ]; then
		chmod +x $t
		exec /bin/bash $t "$@" </dev/fd/2
	else
		rm -f $t
		echo "Direct execution not supported with this shell ($_)." >&2
		echo "Please try bash instead." >&2
		exit 1
	fi
}

# do not modify the two lines below
[ -h /dev/fd/0 ] && run_from_file
#!/bin/bash

########################################
### DEFAULT CONFIGURATION            ###
########################################

# mirror from which to download archlinux packages
archlinux_mirror="http://mirrors.kernel.org/archlinux"

# package to use as kernel (linux or linux-lts)
kernel_package=linux

# migrated machine architecture (x86_64/i686)
target_architecture="$(uname -m)"

# new disklabel type (gpt/dos)
target_disklabel="gpt"

# new filesystem type (ext4/btrfs)
target_filesystem="btrfs"

# running on another VPS service (experimental)
no_digitalocean=0

# NOT EXPOSED NORMALLY: don't prompt
continue_without_prompting=0

# NOT EXPOSED NORMALLY: path to metadata service
meta_base=http://169.254.169.254/metadata/v1/

########################################
### END OF CONFIGURATION             ###
########################################

if [ -n "${POSIXLY_CORRECT}" ] || [ -z "${DEBIAN_TO_ARCH_ENV_CLEARED}" ]; then
	exec /usr/bin/env -i \
		TERM="$TERM" \
		PATH=/usr/sbin:/sbin:/usr/bin:/bin \
		DEBIAN_TO_ARCH_ENV_CLEARED=1 \
		/bin/bash "$0" "$@"
fi

set -eu
set -o pipefail
shopt -s nullglob
shopt -s dotglob
umask 022

sector_size=512

flag_variables=(
	archlinux_mirror
	kernel_package
	target_architecture
	target_disklabel
	target_filesystem
)

host_packages=(
	haveged
	parted
)

arch_packages=(
	grub
	openssh
	sudo
	vim
	git
)

gpt1_size_MiB=1
doroot_size_MiB=6
biosboot_size_MiB=1
archroot_size_MiB=
gpt2_size_MiB=1

doroot_offset_MiB=$((gpt1_size_MiB))
biosboot_offset_MiB=$((doroot_offset_MiB + doroot_size_MiB))
archroot_offset_MiB=$((biosboot_offset_MiB + biosboot_size_MiB))

log() {
	echo "[$(date)]" "$@" >&2
}

fatal() {
	log "$@"
	log "Exiting."
	exit 1
}

extract_embedded_file() {
	awk -v n="$1" '$0=="!!!!"{p=0};p;$0=="!!!!"n{p=1}' "$0"
}

parse_flags() {
	local c conf_key conf_val
	while [ $# -gt 0 ]; do
		conf_key=
		conf_val=
		for c in ${flag_variables[@]}; do
			case "$1" in
				--$c)
					shift
					[ $# -gt 0 ] || fatal "Option $c requires a value."
					conf_key="$c"
					conf_val="$1"
					shift
					break
					;;
				--$c=*)
					conf_key="$c"
					conf_val="${1#*=}"
					shift
					break
					;;
				--i_understand_that_this_droplet_will_be_completely_wiped)
					continue_without_prompting=1
					conf_key=option_acknowledged
					shift
					break
					;;
				--no_digitalocean)
					no_digitalocean=1
					conf_key=option_acknowledged
					shift
					break
					;;
				--help)
					print_help_and_exit
					;;
			esac
		done
		[ "${conf_key}" = option_acknowledged ] && continue
		[ -n "${conf_key}" ] || fatal "Unknown option: $1"
		[ -n "${conf_val}" ] || fatal "Empty value for option ${conf_key}."
		local -n conf_ref=${conf_key}
		conf_ref="${conf_val}"
	done
	log "Configuration:"
	for conf_key in ${flag_variables[@]}; do
		local -n conf_ref=${conf_key}
		log "- ${conf_key} = ${conf_ref}"
	done
}

print_help_and_exit() {
	local conf_key
	echo "Available options: (see script for details)" >&2
	for conf_key in ${flag_variables[@]}; do
		local -n conf_ref=${conf_key}
		echo "  --${conf_key}=[${conf_ref}]" >&2
	done
	exit 1
}

validate_flags_and_augment_globals() {
	arch_packages+=(${kernel_package})
	case "${target_disklabel}" in
		gpt)
			;;
		dos)
			;;
		*)
			fatal "Unknown disklabel type: ${target_disklabel}"
			;;
	esac
	case "${target_filesystem}" in
		ext4)
			;;
		btrfs)
			host_packages+=(btrfs-tools)
			arch_packages+=(btrfs-progs)
			;;
		*)
			fatal "Unknown filesystem type: ${target_filesystem}"
			;;
	esac
	local disk_MiB=$(($(cat /sys/block/vda/size) >> 11))
	archroot_size_MiB=$((disk_MiB - gpt2_size_MiB - archroot_offset_MiB))
}

read_flags() {
	local filename=$1
	source ${filename}
}

write_flags() {
	local filename=$1
	{
		local conf_key
		for conf_key in ${flag_variables[@]}; do
			local -n conf_ref=${conf_key}
			printf "%s=%q\n" "${conf_key}" "${conf_ref}"
		done
	} > ${filename}
}

sanity_checks() {
	[ ${EUID} -eq 0 ] || fatal "Script must be run as root."
	[ ${UID} -eq 0 ] || fatal "Script must be run as root."
	[ -e /dev/vda ] || fatal "Script must be run on a KVM machine."
	[[ "$(cat /etc/debian_version)" == 8.? ]] || \
		fatal "This script only supports Debian 8.x."
}

prompt_for_destruction() {
	(( continue_without_prompting )) && return 0
	log "*** ALL DATA ON THIS DROPLET WILL BE WIPED. ***"
	log "Please backup all important data on this droplet before continuing."
	log 'Type "wipe this droplet" to continue or anything else to cancel.'
	local response
	read -p ' > ' response
	if [ "${response}" = "wipe this droplet" ]; then
		return 0
	else
		log "Cancelled."
		exit 0
	fi
}

download_and_verify() {
	local file_url="$1"
	local local_path="$2"
	local expected_sha1="$3"
	for try in {0..3}; do
		if [ ${try} -eq 0 ]; then
			[ -e "${local_path}" ] || continue
		else
			wget -O "${local_path}" "${file_url}"
		fi
		set -- $(sha1sum "${local_path}")
		if [ $1 = "${expected_sha1}" ]; then
			return 0
		else
			rm -f "${local_path}"
		fi
	done
	return 1
}

build_parted_cmdline() {
	local cmdline=
	local biosboot_name=BIOSBoot
	local doroot_name=DORoot
	local archroot_name=ArchRoot
	if [ ${target_disklabel} = dos ]; then
		cmdline="mklabel msdos"
		biosboot_name=primary
		doroot_name=primary
		archroot_name=primary
	else
		cmdline="mklabel ${target_disklabel}"
	fi
	local archroot_end_MiB=$((archroot_offset_MiB + archroot_size_MiB))
	cmdline+=" mkpart ${doroot_name} ${doroot_offset_MiB}MiB ${biosboot_offset_MiB}MiB"
	cmdline+=" mkpart ${biosboot_name} ${biosboot_offset_MiB}MiB ${archroot_offset_MiB}MiB"
	cmdline+=" mkpart ${archroot_name} ${archroot_offset_MiB}MiB ${archroot_end_MiB}MiB"
	if [ ${target_disklabel} = gpt ]; then
		cmdline+=" set 2 bios_grub on"
	fi
	echo "${cmdline}"
}

setup_loop_device() {
	modprobe loop
	
	local offset_MiB=$1
	local size_MiB=$2
	losetup --find --show --offset ${offset_MiB}MiB --size ${size_MiB}MiB /d2a/work/image
}

package_digitalocean_synchronize() {
	local destination=$1
	local pkgroot=/d2a/work/dosync
	local sysdir=${pkgroot}/usr/lib/systemd/system
	local netdir=${pkgroot}/usr/lib/systemd/network

	mkdir -p ${pkgroot}
	extract_embedded_file digitalocean-synchronize.PKGINFO > ${pkgroot}/.PKGINFO
	mkdir -p ${pkgroot}/usr/bin
	extract_embedded_file digitalocean-synchronize > ${pkgroot}/usr/bin/digitalocean-synchronize
	mkdir -p ${sysdir}
	extract_embedded_file digitalocean-synchronize.service > ${sysdir}/digitalocean-synchronize.service
	mkdir -p ${sysdir}/multi-user.target.wants
	ln -s ../digitalocean-synchronize.service ${sysdir}/multi-user.target.wants
	mkdir -p ${netdir}
	extract_embedded_file 90-virtio-no-rename.link > ${netdir}/90-virtio-no-rename.link

	chmod 0755 ${pkgroot}/usr/bin/digitalocean-synchronize

	( cd ${pkgroot} && tar -cf ${destination} * )
	rm -rf ${pkgroot}
}

kill_processes_in_mountpoint() {
	if mountpoint -q $1; then
		fuser -kms $1 || true
		find /proc -maxdepth 2 -name root -lname $1 | \
			grep -o '[0-9]*' | xargs -r kill || true
	fi
}

quietly_umount() {
	if mountpoint -q $1; then
		umount -d $1
	fi
}

cleanup_work_directory() {
	kill_processes_in_mountpoint /d2a/work/doroot
	kill_processes_in_mountpoint /d2a/work/archroot
	quietly_umount /d2a/work/doroot
	quietly_umount /d2a/work/archroot/var/cache/pacman/pkg
	quietly_umount /d2a/work/archroot/dev/pts
	quietly_umount /d2a/work/archroot/dev
	quietly_umount /d2a/work/archroot/sys
	quietly_umount /d2a/work/archroot/proc
	quietly_umount /d2a/work/archroot
	rm -rf --one-file-system /d2a/work
}

stage1_install_exit() {
	set +e
	cleanup_work_directory
}

stage1_install() {
	trap stage1_install_exit EXIT
	cleanup_work_directory
	mkdir -p /d2a/work

	log "Installing required packages ..."
	DEBIAN_FRONTEND=noninteractive apt-get install -y ${host_packages[@]}

	log "Partitioning image ..."
	local disk_sectors=$(cat /sys/block/vda/size)
	rm -f /d2a/work/image
	truncate -s $((disk_sectors * sector_size)) /d2a/work/image
	parted /d2a/work/image $(build_parted_cmdline)

	log "Formatting image ..."
	local doroot_loop=$(setup_loop_device ${doroot_offset_MiB} ${doroot_size_MiB})
	local archroot_loop=$(setup_loop_device ${archroot_offset_MiB} ${archroot_size_MiB})
	[[ $no_digitalocean -eq 1 ]] || mkfs.ext4 -L DOROOT ${doroot_loop}
	mkfs.${target_filesystem} -L ArchRoot ${archroot_loop}

	log "Mounting image ..."
	mkdir -p /d2a/work/{doroot,archroot}
	mount ${archroot_loop} /d2a/work/archroot

	if [[ $no_digitalocean -eq 0 ]]; then
		mount ${doroot_loop} /d2a/work/doroot

		log "Setting up DOROOT ..."
		mkdir -p /d2a/work/doroot/etc/network
		touch /d2a/work/doroot/etc/network/interfaces
		cat > /d2a/work/doroot/README <<-EOF
			DO NOT TOUCH FILES ON THIS PARTITION.

			The DOROOT partition is where DigitalOcean writes passwords and other data
			when a droplet is rebuilt from an image or restored from a snapshot.
			If certain files are missing, restores/rebuilds will not work and you will
			end up with an unusable image.

			The digitalocean-synchronize script also watches this partition.
			If this partition (particularly etc/shadow) is written to, the script will
			reset the root password to the one provided by DigitalOcean and wipe all
			SSH host keys for security.
		EOF
		chmod 0444 /d2a/work/doroot/README
	fi

	log "Downloading bootstrap tarball ..."
	set -- $(wget -qO- ${archlinux_mirror}/iso/latest/sha1sums.txt |
		grep "archlinux-bootstrap-[^-]*-${target_architecture}.tar.gz")
	local expected_sha1=$1
	local bootstrap_filename=$2
	download_and_verify \
		${archlinux_mirror}/iso/latest/${bootstrap_filename} \
		/d2a/bootstrap.tar.gz \
		${expected_sha1}

	log "Extracting bootstrap tarball ..."
	tar -xzf /d2a/bootstrap.tar.gz \
		--directory=/d2a/work/archroot \
		--strip-components=1

	log "Mounting virtual filesystems ..."
	mount -t proc proc /d2a/work/archroot/proc
	mount -t sysfs sys /d2a/work/archroot/sys
	mount -t devtmpfs dev /d2a/work/archroot/dev
	mkdir -p /d2a/work/archroot/dev/pts
	mount -t devpts pts /d2a/work/archroot/dev/pts

	log "Binding packages directory ..."
	mkdir -p /d2a/packages
	mount --bind /d2a/packages /d2a/work/archroot/var/cache/pacman/pkg

	log "Preparing bootstrap filesystem ..."
	echo "Server = ${archlinux_mirror}/\$repo/os/\$arch" > /d2a/work/archroot/etc/pacman.d/mirrorlist
	
	cat > /d2a/work/archroot/etc/resolv.conf <<-EOF
		# Google IPv6 nameservers
		nameserver 2001:4860:4860::8888
		nameserver 2001:4860:4860::8844
		
		# Google IPv4 nameservers
		nameserver 8.8.8.8
		nameserver 8.8.4.4
	EOF

	log "Installing base system ..."
	chroot /d2a/work/archroot pacman-key --init
	chroot /d2a/work/archroot pacman-key --populate archlinux
	local chroot_pacman="chroot /d2a/work/archroot pacman --arch ${target_architecture}"
	${chroot_pacman} -Sy
	${chroot_pacman} -Su --noconfirm --needed \
		$(${chroot_pacman} -Sgq base | grep -v '^linux$') \
		${arch_packages[@]}

	log "Configuring base system ..."
	hostname > /d2a/work/archroot/etc/hostname
	cp /etc/ssh/ssh_host_* /d2a/work/archroot/etc/ssh/
	local encrypted_password=$(awk -F: '$1 == "root" { print $2 }' /etc/shadow)
	chroot /d2a/work/archroot usermod -p "${encrypted_password}" root
	chroot /d2a/work/archroot systemctl enable systemd-networkd.service
	chroot /d2a/work/archroot systemctl enable sshd.service

	if [[ $no_digitalocean -eq 0 ]]; then
		package_digitalocean_synchronize /d2a/work/archroot/dosync.pkg.tar
		${chroot_pacman} -U --noconfirm /dosync.pkg.tar
		rm /d2a/work/archroot/dosync.pkg.tar
	fi

	local authkeys
	if authkeys="$(wget -qO- -T5 -t1 ${meta_base}public-keys)" && test -z "${authkeys}"; then
		log "*** WARNING ***"
		log "SSH public keys are not configured for this droplet."
		log "PermitRootLogin will be enabled in sshd_config to permit root logins over SSH."
		log "This is a security risk, as passwords are not as secure as public keys."
		log "To set up public keys, visit the following URL: https://goo.gl/iEgFRs"
		log "Remember to remove the PermitRootLogin option from sshd_config after doing so."
		cat >> /d2a/work/archroot/etc/ssh/sshd_config <<-EOF

			# This enables password logins to root over SSH.
			# This is insecure; see https://goo.gl/iEgFRs to set up public keys.
			PermitRootLogin yes

		EOF
	fi

	log "Finishing up image generation ..."
	ln -f /d2a/work/image /d2a/image
	cleanup_work_directory
	trap - EXIT
}

bisect_left_on_allocation() {
	local alloc_start_sector=$1
	local alloc_end_sector=$2
	local -n bisection_output=$3
	local -n allocation_map=$4
	local lo=0 hi=${#allocation_map[@]}
	while (( lo < hi )); do
		local mid=$(((lo+hi)/2))
		set -- ${allocation_map[$mid]}
		if (( $# == 0 )) || (( $1 < alloc_start_sector )); then
			lo=$((mid+1))
		else
			hi=$((mid))
		fi
	done
	bisection_output=$lo
}

check_for_allocation_overlap() {
	local check_start_sector=$1
	local check_end_sector=$2
	local -n overlap_start_sector=$3
	local -n overlap_end_sector=$4
	shift 4
	local allocation_maps="$*"

	# overlap_end_sector = 0 if no overlap
	overlap_start_sector=0
	overlap_end_sector=0

	local map_name
	for map_name in ${allocation_maps}; do
		local -n allocation_map=${map_name}
		local map_length=${#allocation_map[@]}
		(( ${map_length} )) || continue
		local bisection_index
		bisect_left_on_allocation ${check_start_sector} ${check_end_sector} \
			bisection_index ${map_name}
		local check_index
		for check_index in $((bisection_index - 1)) $((bisection_index)); do
			(( check_index < 0 || check_index >= map_length )) && continue
			set -- ${allocation_map[${check_index}]}
			(( $# == 0 )) && continue
			local alloc_start_sector=$1
			local alloc_end_sector=$2
			(( check_start_sector >= alloc_end_sector || alloc_start_sector >= check_end_sector )) && continue
			# overlap detected
			overlap_start_sector=$((alloc_start_sector > check_start_sector ?
				alloc_start_sector : check_start_sector))
			overlap_end_sector=$((alloc_end_sector < check_end_sector ?
				alloc_end_sector : check_end_sector))
			return
		done
	done
}

insert_into_allocation_map() {
	local -n allocation_map=$1
	shift
	local alloc_start_sector=$1
	local alloc_end_sector=$2
	if (( ${#allocation_map[@]} == 0 )); then
		allocation_map=("$*")
	else
		local bisection_index
		bisect_left_on_allocation ${alloc_start_sector} ${alloc_end_sector} \
			bisection_index ${!allocation_map}
		allocation_map=(
			"${allocation_map[@]:0:${bisection_index}}"
			"$*"
			"${allocation_map[@]:${bisection_index}}")
	fi
}

stage2_arrange() {
	local disk_sectors=$(cat /sys/block/vda/size)
	local root_device=$(awk '$2 == "/" { root = $1 } END { print root }' /proc/mounts)
	local root_offset_sectors=0
	if [[ $root_device != "/dev/vda" ]]; then
		root_offset_sectors=$(cat /sys/block/vda/${root_device#/dev/}/start)
	fi
	local srcdst_map=()     # original source to target map
	local unalloc_map=()    # extents not used by either source or target (for tmpdst_map)
	local tmpdst_map=()     # extents on temporary redirection (allocated from unalloc_map)
	local source_start_sector source_end_sector target_start_sector target_end_sector

	log "Creating block rearrangement plan ..."

	# get and sort extents
	filefrag -e -s -v -b${sector_size} /d2a/image | \
		sed '/^ *[0-9]*:/!d;s/[:.]/ /g' | \
		sort -nk4 > /d2a/imagemap
	while read line; do
		set -- ${line}
		source_start_sector=$(($4 + root_offset_sectors))
		source_end_sector=$((source_start_sector + $6))
		target_start_sector=$2
		target_end_sector=$((target_start_sector + $6))
		echo ${source_start_sector} ${source_end_sector}
		echo ${target_start_sector} ${target_end_sector}
		srcdst_map+=("${source_start_sector} ${source_end_sector} ${target_start_sector}")
	done < /d2a/imagemap > /d2a/unsortedallocs
	sort -n < /d2a/unsortedallocs > /d2a/sortedallocs

	# build map of unallocated sectors
	local unalloc_start_sector=0 unalloc_end_sector=${disk_sectors}
	while read source_start_sector source_end_sector; do
		if (( source_end_sector <= unalloc_start_sector )); then
			# does not overlap unallocated part
			continue
		elif (( source_start_sector > unalloc_start_sector )); then
			# full overlap with unallocated part
			unalloc_map+=("${unalloc_start_sector} ${source_start_sector}")
			unalloc_start_sector=${source_end_sector}
		else
			# partial overlap
			unalloc_start_sector=${source_end_sector}
		fi
	done < /d2a/sortedallocs
	if (( unalloc_start_sector != unalloc_end_sector )); then
		unalloc_map+=("${unalloc_start_sector} ${unalloc_end_sector}")
	fi

	# open blockplan
	exec {blockplan_fd}>/d2a/blockplan

	# arrange sectors
	while (( ${#srcdst_map[@]} )); do
		set -- ${srcdst_map[-1]}
		source_start_sector=$1
		source_end_sector=$2
		target_start_sector=$3
		target_end_sector=$((target_start_sector + (source_end_sector - source_start_sector)))
		if (( source_start_sector == target_start_sector )); then
			unset 'srcdst_map[-1]'
			continue
		elif (( target_start_sector >= source_end_sector ||
				source_start_sector >= target_end_sector )); then
			unset 'srcdst_map[-1]'
		else
			local new_extent_sectors=$((target_start_sector - source_start_sector))
			new_extent_sectors=${new_extent_sectors#-}  # absolute value
			set -- \
				$((source_start_sector + new_extent_sectors)) \
				$((source_end_sector)) \
				$((target_start_sector + new_extent_sectors))
			srcdst_map[-1]="$*"
			source_end_sector=$((source_start_sector + new_extent_sectors))
		fi
		local overlap_start_sector overlap_end_sector
		check_for_allocation_overlap \
			${target_start_sector} ${target_end_sector} \
			overlap_start_sector overlap_end_sector \
			srcdst_map
		if (( overlap_end_sector )); then
			# insert non-overlapping parts back into srcdst_map
			if (( target_start_sector < overlap_start_sector )); then
				local nonoverlap_length_sectors=$((overlap_start_sector - target_start_sector))
				insert_into_allocation_map srcdst_map \
					${source_start_sector} \
					$((source_start_sector + nonoverlap_length_sectors)) \
					${target_start_sector}
			fi
			if (( target_end_sector > overlap_end_sector )); then
				local nonoverlap_length_sectors=$((target_end_sector - overlap_end_sector))
				insert_into_allocation_map srcdst_map \
					$((source_end_sector - nonoverlap_length_sectors)) \
					${source_end_sector} \
					${overlap_end_sector}
			fi
			# copy overlapping portion into tmpdst_map
			while (( overlap_start_sector < overlap_end_sector )); do
				set -- ${unalloc_map[-1]}
				unset 'unalloc_map[-1]'  # or nullglob will eat it up
				local unalloc_start_sector=$1
				local unalloc_end_sector=$2
				local unalloc_length_sectors=$((unalloc_end_sector - unalloc_start_sector))
				local overlap_length_sectors=$((overlap_end_sector - overlap_start_sector))
				if (( overlap_length_sectors < unalloc_length_sectors )); then
					# return unused portion to unalloc_map
					unalloc_map+=("${unalloc_start_sector} $((unalloc_end_sector - overlap_length_sectors))")
					unalloc_start_sector=$((unalloc_end_sector - overlap_length_sectors))
					unalloc_length_sectors=${overlap_length_sectors}
				fi
				echo >&${blockplan_fd} \
					$((source_start_sector + (overlap_start_sector - target_start_sector))) \
					${unalloc_start_sector} \
					${unalloc_length_sectors}
				insert_into_allocation_map tmpdst_map \
					${unalloc_start_sector} \
					${unalloc_end_sector} \
					${overlap_start_sector}
				(( overlap_start_sector += unalloc_length_sectors ))
			done
		else
			echo >&${blockplan_fd} \
				${source_start_sector} \
				${target_start_sector} \
				$((source_end_sector - source_start_sector))
		fi
	done

	# restore overlapped sectors
	while (( ${#tmpdst_map[@]} )); do
		set -- ${tmpdst_map[-1]}
		unset 'tmpdst_map[-1]'
		source_start_sector=$1
		source_end_sector=$2
		target_start_sector=$3
		echo >&${blockplan_fd} \
			${source_start_sector} \
			${target_start_sector} \
			$((source_end_sector - source_start_sector))
	done

	# close blockplan
	exec {blockplan_fd}>&-
}

cleanup_mid_directory() {
	quietly_umount /d2a/mid
	rm -rf --one-file-system /d2a/mid
}

add_binary_to_mid() {
	mkdir -p $(dirname /d2a/mid/$1)
	cp $1 /d2a/mid/$1
	ldd $1 | grep -o '/[^ ]* (0x[0-9a-f]*)' | \
			while read libpath ignored; do
		[ -e /d2a/mid/${libpath} ] && continue
		mkdir -p $(dirname /d2a/mid/${libpath})
		cp ${libpath} /d2a/mid/${libpath}
	done
}

stage3_prepare_exit() {
	set +e
	cleanup_mid_directory
}

stage3_prepare() {
	trap stage3_prepare_exit EXIT
	cleanup_mid_directory
	mkdir -p /d2a/mid

	# mount tmpfs
	mount -t tmpfs mid /d2a/mid

	# make sure busybox is installed
	apt-get -yqq install busybox

	# add binaries
	add_binary_to_mid /bin/busybox
	add_binary_to_mid /bin/bash

	# create symlinks
	local dir
	for dir in bin sbin usr/bin usr/sbin; do mkdir -p /d2a/mid/${dir}; done
	ln -s bash /d2a/mid/bin/sh
	chroot /d2a/mid /bin/busybox --install

	# create directories (will be filled by systemd)
	mkdir /d2a/mid/{proc,sys,dev}

	# copy in the blockplan
	cp /d2a/blockplan /d2a/mid/blockplan

	# write out flags
	write_flags /d2a/mid/flags

	# copy myself
	cat "$0" > /d2a/mid/init
	chmod 0755 /d2a/mid/init

	# detach all loop devices
	losetup -D || true

	# reboot!
	log "The machine will now reboot."
	log "Check the console for errors if the machine is still unaccessible after a few minutes."
	sleep 1
	trap - EXIT
	systemctl switch-root /d2a/mid /init
}

stage4_convert_exit() {
	log "Error occurred. You're on your own!"
	exec /bin/bash </dev/console >/dev/console 2>&1
}

stage4_convert() {
	trap stage4_convert_exit EXIT

	# unmount old root
	local retry
	for retry in 1 2 3 4 5; do
		if umount /mnt; then
			retry=0
			break
		else
			sleep 1
		fi
	done
	if (( retry )); then
		umount -rl /mnt
	fi

	# get total number of sectors
	local processed_length=0
	local total_length=$(awk '{x+=$3}END{print+x}' /blockplan)
	local prev_percentage=-1
	local next_percentage=-1

	# execute the block plan
	local source_sector target_sector extent_length
	while read source_sector target_sector extent_length; do
		# increment processed length before extent length gets optimized
		(( processed_length += extent_length )) || true
		# optimize extent length
		local transfer_size=${sector_size}
		until (( (source_sector & 1) || (target_sector & 1) ||
				(extent_length & 1) || (transfer_size >= 0x100000) )); do
			(( source_sector >>= 1 , target_sector >>= 1 , extent_length >>= 1,
				transfer_size <<= 1 )) || true
		done
		# do the actual transfer
		dd if=/dev/vda of=/dev/vda bs=${transfer_size} \
			skip=${source_sector} seek=${target_sector} \
			count=${extent_length} 2>/dev/null
		# print out the percentage
		next_percentage=$((100 * processed_length / total_length))
		if (( next_percentage != prev_percentage )); then
			printf "\rTransferring blocks ... %s%%" ${next_percentage}
			prev_percentage=${next_percentage}
		fi
	done < /blockplan
	echo

	# reread partition table
	blockdev --rereadpt /dev/vda

	# install bootloader
	mkdir /archroot
	mount /dev/vda3 /archroot
	mount -t proc proc /archroot/proc
	mount -t sysfs sys /archroot/sys
	mount -t devtmpfs dev /archroot/dev
	chroot /archroot grub-mkconfig -o /boot/grub/grub.cfg
	chroot /archroot grub-install /dev/vda
	umount /archroot/dev
	umount /archroot/sys
	umount /archroot/proc
	umount /archroot

	# we're done!
	sync
	reboot -f
}

reinstall_digitalocean_synchronize() {
	local package_file=$(mktemp --suffix=.pkg.tar)
	package_digitalocean_synchronize ${package_file}
	pacman -U --noconfirm ${package_file}
	rm ${package_file}
}

if [ -e /var/lib/pacman ]; then
	if [ $# -eq 0 ]; then
		reinstall_digitalocean_synchronize
	else
		log "Run this script to install/update the digitalocean-synchronize package."
	fi
	exit 0
fi

if [ $$ -ne 1 ]; then
	parse_flags "$@"
	sanity_checks
	validate_flags_and_augment_globals
	prompt_for_destruction
	stage1_install
	stage2_arrange
	stage3_prepare
else
	read_flags /flags
	validate_flags_and_augment_globals
	stage4_convert
fi
exit 0

cat <<'EMBEDDED'

!!!!digitalocean-synchronize
#!/bin/bash

meta_base=http://169.254.169.254/metadata/v1/

set -eu
set -o pipefail
shopt -s nullglob
shopt -s dotglob
umask 022

log() {
	logger -t digitalocean-synchronize "$@" || \
		echo "[$(date)]" "$@" >&2
}

netmask_to_prefix() {
	local pfx=0 cmp msk
	for cmp in ${1//./ } 0; do
		for msk in 128 64 32 16 8 4 2 1; do
			if (( cmp & msk )); then
				(( pfx += 1 ))
			else
				echo ${pfx}
				return
			fi
		done
	done
}

update_shadow_if_changed() {
	local etcdir=$1/etc
	mkdir -p ${etcdir} || return 0
	if [ -e ${etcdir}/shadow ]; then
		# change password if file was touched
		local encrypted_password=$(awk -F: '$1 == "root" { print $2 }' ${etcdir}/shadow)
		if [ "${encrypted_password}" != "z" ]; then
			log "Snapshot restore detected."
			usermod -p "${encrypted_password}" root
			if [ ${#encrypted_password} -gt 1 ]; then
				chage -d 0 root
			fi
			log "Password has been reset."
			rm -f /etc/ssh/ssh_host_key /etc/ssh/ssh_host_*_key
			log "SSH host keys will be regenerated."
		fi
	fi
	cat > ${etcdir}/shadow <<-EOF
		root:z:1::::::
		nobody:z:1::::::
	EOF
	chmod 0600 ${etcdir}/shadow
}

process_interface() {
	local url=$1
	local attrs=$2
	local mac=$(curl -Ssf ${url}mac)
	local type=$(curl -Ssf ${url}type)
	local interface=
	local cand path
	for cand in $(ls /sys/class/net); do
		path=/sys/class/net/${cand}/address
		if [ -e ${path} ] && [ "$(<${path})" = "${mac}" ]; then
			interface=${cand}
			break
		fi
	done
	[ -n "${interface}" ] || return 0
	mkdir -p /run/systemd/network
	{
		cat <<-EOF
			# Generated by digitalocean-synchronize
			[Match]
			Name=${interface}
			[Network]
		EOF
		if [[ " ${attrs} " =~ " ipv4/ " ]]; then
			local address=$(curl -sf ${url}ipv4/address)
			local prefix=$(netmask_to_prefix $(curl -sf ${url}ipv4/netmask))
			echo "Address=${address}/${prefix}"
			if [ "${type}" != "private" ]; then
				echo "Gateway=$(curl -sf ${url}ipv4/gateway)"
			fi
			log "Added IPv4 address ${address}/${prefix} on ${interface}."
		fi
		if [[ " ${attrs} " =~ " ipv6/ " ]]; then
			local address=$(curl -sf ${url}ipv6/address)
			local prefix=$(curl -sf ${url}ipv6/cidr)
			echo "Address=${address}/${prefix}"
			if [ "${type}" != "private" ]; then
				echo "Gateway=$(curl -sf ${url}ipv6/gateway)"
			fi
			log "Added IPv6 address ${address}/${prefix} on ${interface}."
		fi
		local network_tail=/etc/systemd/network/template/dosync-${interface}.network.tail
		if [[ -r "${network_tail}" ]]; then
			cat ${network_tail}
			log "Appended user specified config for ${interface}."
		fi
	} > /run/systemd/network/dosync-${interface}.network
}

traverse_interfaces() {
	local url=$1
	set -- $(curl -Ssf ${url})
	if [[ " $* " =~ " mac " ]]; then
		process_interface ${url} "$*"
	else
		local dir
		for dir in $*; do
			# only want dirs with slash suffix
			[ "${dir}" = "${dir%/}" ] && continue
			traverse_interfaces ${url}${dir}
		done
	fi
}

setup_from_metadata_service() {
	local sshkeys
	if sshkeys=$(curl -Ssf ${meta_base}public-keys) && test -n "${sshkeys}"; then
		[ -d /root/.ssh ] || mkdir -m 0700 /root/.ssh
		[ -e /root/.ssh/authorized_keys ] || touch /root/.ssh/authorized_keys
		if ! grep -q "${sshkeys}" /root/.ssh/authorized_keys; then
			printf '\n%s\n' "${sshkeys}" >> /root/.ssh/authorized_keys
			log "Added SSH public keys from metadata service."
		fi
	fi
	local hostname
	if ! test -e /etc/hostname && hostname=$(curl -Ssf ${meta_base}hostname); then
		echo "${hostname}" > /etc/hostname
		hostname "${hostname}"
		log "Hostname set to ${hostname} from metadata service."
	fi
	traverse_interfaces ${meta_base}interfaces/
}

digitalocean_synchronize() {
	if test -e /dev/disk/by-label/DOROOT && mkdir -p /mnt/doroot; then
		mount /dev/disk/by-label/DOROOT /mnt/doroot
		update_shadow_if_changed /mnt/doroot
		umount /mnt/doroot
	else
		log "Unable to check DOROOT for snapshot check!"
	fi

	ip link set dev eth0 up
	ip addr add dev eth0 169.254.169.252/30 2>/dev/null || true
	local retry
	for retry in {1..20}; do
		log "Attempting to connect to metadata service ..."
		if curl -Ssf -m 1 ${meta_base} >/dev/null; then
			setup_from_metadata_service
			break
		else
			log "Unable to connect to metadata service!"
			sleep 1
		fi
	done
	ip addr del dev eth0 169.254.169.252/30 2>/dev/null || true
}

digitalocean_synchronize
!!!!

!!!!digitalocean-synchronize.service
[Unit]
Description=DigitalOcean Synchronization
DefaultDependencies=no
Before=systemd-networkd.service
After=systemd-udevd.service

[Service]
Type=oneshot
ExecStart=/usr/sbin/digitalocean-synchronize
!!!!

!!!!digitalocean-synchronize.PKGINFO
pkgname = digitalocean-synchronize
pkgver = 2.4-2
pkgdesc = DigitalOcean Synchronization (passwords, keys, networks)
url = https://github.com/lesderid/digitalocean-debian-to-arch
arch = any
license = GPL
!!!!

!!!!90-virtio-no-rename.link
# Prevent virtio network devices from being renamed.
[Match]
Driver=virtio_net
[Link]
NamePolicy=kernel
!!!!

EMBEDDED