#!/bin/sh
#    Copyright (C) 2011 Canonical Ltd.
#    Copyright (C) 2013 Hewlett-Packard Development Company, L.P.
#
#    Authors: Scott Moser <smoser@canonical.com>
#             Juerg Haefliger <juerg.haefliger@hp.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, version 3 of the License.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

# the fudge factor. if within this many bytes dont bother
FUDGE=${GROWPART_FUDGE:-$((1024*1024))}
TEMP_D=""
RESTORE_FUNC=""
RESTORE_HUMAN=""
VERBOSITY=0
DISK=""
PART=""
PT_UPDATE=false
DRY_RUN=0

SFDISK_VERSION=""
SFDISK_2_26="22600"
SFDISK_V_WORKING_GPT="22603"
MBR_BACKUP=""
GPT_BACKUP=""
_capture=""

error() {
	echo "$@" 1>&2
}

fail() {
	[ $# -eq 0 ] || echo "FAILED:" "$@"
	exit 2
}

nochange() {
	echo "NOCHANGE:" "$@"
	exit 1
}

changed() {
	echo "CHANGED:" "$@"
	exit 0
}

change() {
	echo "CHANGE:" "$@"
	exit 0
}

cleanup() {
	if [ -n "${RESTORE_FUNC}" ]; then
		error "***** WARNING: Resize failed, attempting to revert ******"
		if ${RESTORE_FUNC} ; then
			error "***** Restore appears to have gone OK ****"
		else
			error "***** Restore FAILED! ******"
			if [ -n "${RESTORE_HUMAN}" -a -f "${RESTORE_HUMAN}" ]; then
				error "**** original table looked like: ****"
				cat "${RESTORE_HUMAN}" 1>&2
			else
				error "We seem to have not saved the partition table!"
			fi
		fi
	fi
	[ -z "${TEMP_D}" -o ! -d "${TEMP_D}" ] || rm -Rf "${TEMP_D}"
}

debug() {
	local level=${1}
	shift
	[ "${level}" -gt "${VERBOSITY}" ] && return
	if [ "${DEBUG_LOG}" ]; then
		echo "$@" >>"${DEBUG_LOG}"
	else
		error "$@"
	fi
}

debugcat() {
	local level="$1"
	shift;
	[ "${level}" -gt "$VERBOSITY" ] && return
	if [ "${DEBUG_LOG}" ]; then
		cat "$@" >>"${DEBUG_LOG}"
	else
		cat "$@" 1>&2
	fi
}

mktemp_d() {
	# just a mktemp -d that doens't need mktemp if its not there.
	_RET=$(mktemp -d "${TMPDIR:-/tmp}/${0##*/}.XXXXXX" 2>/dev/null) &&
		return
	_RET=$(umask 077 && t="${TMPDIR:-/tmp}/${0##*/}.$$" &&
		mkdir "${t}" &&	echo "${t}")
	return
}

Usage() {
	cat <<EOF
${0##*/} disk partition
   rewrite partition table so that partition takes up all the space it can
   options:
    -h | --help       print Usage and exit
         --fudge F    if part could be resized, but change would be
                      less than 'F' bytes, do not resize (default: ${FUDGE})
    -N | --dry-run    only report what would be done, show new 'sfdisk -d'
    -v | --verbose    increase verbosity / debug
    -u | --update  R  update the the kernel partition table info after growing
                      this requires kernel support and 'partx --update'
                      R is one of:
                       - 'auto'  : [default] update partition if possible
                       - 'force' : try despite sanity checks (fail on failure)
                       - 'off'   : do not attempt
                       - 'on'    : fail if sanity checks indicate no support

   Example:
    - ${0##*/} /dev/sda 1
      Resize partition 1 on /dev/sda
EOF
}

bad_Usage() {
	Usage 1>&2
	error "$@"
	exit 2
}

sfdisk_restore_legacy() {
	sfdisk --no-reread "${DISK}" -I "${MBR_BACKUP}"
}

sfdisk_restore() {
	# files are named: sfdisk-<device>-<offset>.bak
	local f="" offset="" fails=0
	for f in "${MBR_BACKUP}"*.bak; do
		[ -f "$f" ] || continue
		offset=${f##*-}
		offset=${offset%.bak}
		[ "$offset" = "$f" ] && {
			error "WARN: confused by file $f";
			continue;
		}
		dd "if=$f" "of=${DISK}" seek=$(($offset)) bs=1 conv=notrunc ||
			{ error "WARN: failed restore from $f"; fails=$(($fails+1)); }
	done
	return $fails
}

sfdisk_worked_but_blkrrpart_failed() {
	local ret="$1" output="$2"
	# exit code found was just 1, but dont insist on that
	#[ $ret -eq 1 ] || return 1
	# Successfully wrote the new partition table
	if grep -qi "Success.* wrote.* new.* partition" "$output"; then
		grep -qi "BLKRRPART: Device or resource busy" "$output"
		return
	# The partition table has been altered.
	elif grep -qi "The.* part.* table.* has.* been.* altered" "$output"; then
		# Re-reading the partition table failed
		grep -qi "Re-reading.* partition.* table.* failed" "$output"
		return
	fi
	return $ret
}

get_sfdisk_version() {
	# set SFDISK_VERSION to MAJOR*10000+MINOR*100+MICRO
	local out oifs="$IFS" ver=""
	[ -n "$SFDISK_VERSION" ] && return 0
	# expected output: sfdisk from util-linux 2.25.2
	out=$(sfdisk --version) ||
		{ error "failed to get sfdisk version"; return 1; }
	set -- $out
	ver=$4
	case "$ver" in
		[0-9]*.[0-9]*.[0-9]|[0-9].[0-9]*)
			IFS="."; set -- $ver; IFS="$oifs"
			SFDISK_VERSION=$(($1*10000+$2*100+${3:-0}))
			return 0;;
		*) error "unexpected output in sfdisk --version [$out]"
			return 1;;
	esac
}

resize_sfdisk() {
	local humanpt="${TEMP_D}/recovery"
	local mbr_backup="${TEMP_D}/orig.save"
	local restore_func=""
	local format="$1"

	local change_out=${TEMP_D}/change.out
	local dump_out=${TEMP_D}/dump.out
	local new_out=${TEMP_D}/new.out
	local dump_mod=${TEMP_D}/dump.mod
	local tmp="${TEMP_D}/tmp.out"
	local err="${TEMP_D}/err.out"
	local mbr_max_512="4294967296"

	local pt_start pt_size pt_end max_end new_size change_info dpart
	local sector_num sector_size disk_size tot out

	rqe sfd_list sfdisk --list --unit=S "$DISK" >"$tmp" ||
		fail "failed: sfdisk --list $DISK"
	if [ "${SFDISK_VERSION}" -lt ${SFDISK_2_26} ]; then
		# exected output contains: Units: sectors of 512 bytes, ...
		out=$(awk '$1 == "Units:" && $5 ~ /bytes/ { print $4 }' "$tmp") ||
			fail "failed to read sfdisk output"
		if [ -z "$out" ]; then
			error "WARN: sector size not found in sfdisk output, assuming 512"
			sector_size=512
		else
			sector_size="$out"
		fi
		local _w _cyl _w1 _heads _w2 sectors _w3 t s
		# show-size is in units of 1024 bytes (same as /proc/partitions)
		t=$(sfdisk --show-size "${DISK}") ||
			fail "failed: sfdisk --show-size $DISK"
		disk_size=$((t*1024))
		sector_num=$(($disk_size/$sector_size))
		msg="disk size '$disk_size' not evenly div by sector size '$sector_size'"
		[ "$((${disk_size}%${sector_size}))" -eq 0 ] ||
			error "WARN: $msg"
		restore_func=sfdisk_restore_legacy
	else
		# --list first line output:
		# Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
		local _x
		read _x _x _x _x disk_size _x sector_num _x  < "$tmp"
		sector_size=$((disk_size/$sector_num))
		restore_func=sfdisk_restore
	fi

	debug 1 "$sector_num sectors of $sector_size. total size=${disk_size} bytes"

	rqe sfd_dump sfdisk --unit=S --dump "${DISK}" >"${dump_out}" ||
		fail "failed to dump sfdisk info for ${DISK}"
	RESTORE_HUMAN="$dump_out"

	{
		echo "## sfdisk --unit=S --dump ${DISK}"
		cat "${dump_out}"
	}  >"$humanpt"

	[ $? -eq 0 ] || fail "failed to save sfdisk -d output"
	RESTORE_HUMAN="$humanpt"

	debugcat 1 "$humanpt"

	sed -e 's/,//g; s/start=/start /; s/size=/size /' "${dump_out}" \
		>"${dump_mod}" ||
		fail "sed failed on dump output"

	dpart="${DISK}${PART}" # disk and partition number
	if [ -b "$DISK" ]; then
		if [ -b "${DISK}p${PART}" -a "${DISK%[0-9]}" != "${DISK}" ]; then
			# for block devices that end in a number (/dev/nbd0)
			# the partition is "<name>p<partition_number>" (/dev/nbd0p1)
			dpart="${DISK}p${PART}"
		elif [ "${DISK#/dev/loop[0-9]}" != "${DISK}" ]; then
			# for /dev/loop devices, sfdisk output will be <name>p<number>
			# format also, even though there is not a device there.
			dpart="${DISK}p${PART}"
		fi
	else
		case "$DISK" in
			# sfdisk for files ending in digit to <disk>p<num>.
			*[0-9]) dpart="${DISK}p${PART}";;
		esac
	fi

	pt_start=$(awk '$1 == pt { print $4 }' "pt=${dpart}" <"${dump_mod}") &&
		pt_size=$(awk '$1 == pt { print $6 }' "pt=${dpart}" <"${dump_mod}") &&
		[ -n "${pt_start}" -a -n "${pt_size}" ] &&
		pt_end=$((${pt_size}+${pt_start})) ||
		fail "failed to get start and end for ${dpart} in ${DISK}"

	# find the minimal starting location that is >= pt_end
	max_end=$(awk '$3 == "start" { if($4 >= pt_end && $4 < min)
		{ min = $4 } } END { printf("%s\n",min); }' \
		min=${sector_num} pt_end=${pt_end} "${dump_mod}") &&
		[ -n "${max_end}" ] ||
		fail "failed to get max_end for partition ${PART}"

	if [ "$format" = "gpt" ]; then
		# sfdisk respects 'last-lba' in input, and complains about
		# partitions that go past that.  without it, it does the right thing.
		sed -i '/^last-lba:/d' "$dump_out" ||
			fail "failed to remove last-lba from output"
	fi
	if [ "$format" = "dos" ]; then
		mbr_max_sectors=$((mbr_max_512*$((sector_size/512))))
		if [ "$max_end" -gt "$mbr_max_sectors" ]; then
			max_end=$mbr_max_sectors
		fi
		[ $(($disk_size/512)) -gt $mbr_max_512 ] &&
			debug 0 "WARNING: MBR/dos partitioned disk is larger than 2TB." \
				"Additional space will go unused."
	fi

	local gpt_second_size="33"
	if [ "${max_end}" -gt "$((${sector_num}-${gpt_second_size}))" ]; then
		# if mbr allow subsequent conversion to gpt without shrinking the
		# partition.  safety net at cost of 33 sectors, seems reasonable.
		# if gpt, we can't write there anyway.
		debug 1 "padding ${gpt_second_size} sectors for gpt secondary header"
		max_end=$((${sector_num}-${gpt_second_size}))
	fi

	debug 1 "max_end=${max_end} tot=${sector_num} pt_end=${pt_end}" \
		"pt_start=${pt_start} pt_size=${pt_size}"
	[ $((${pt_end})) -eq ${max_end} ] &&
		nochange "partition ${PART} is size ${pt_size}. it cannot be grown"
	[ $((${pt_end}+(${FUDGE}/$sector_size))) -gt ${max_end} ] &&
		nochange "partition ${PART} could only be grown by" \
		"$((${max_end}-${pt_end})) [fudge=$((${FUDGE}/$sector_size))]"

	# now, change the size for this partition in ${dump_out} to be the
	# new size
	new_size=$((${max_end}-${pt_start}))
	sed "\|^\s*${dpart} |s/\(.*\)${pt_size},/\1${new_size},/" "${dump_out}" \
		>"${new_out}" ||
		fail "failed to change size in output"

	change_info="partition=${PART} start=${pt_start}"
	change_info="${change_info} old: size=${pt_size} end=${pt_end}"
	change_info="${change_info} new: size=${new_size} end=${max_end}"
	if [ ${DRY_RUN} -ne 0 ]; then
		echo "CHANGE: ${change_info}"
		{
			echo "# === old sfdisk -d ==="
			cat "${dump_out}"
			echo "# === new sfdisk -d ==="
			cat "${new_out}"
		} 1>&2
		exit 0
	fi

	MBR_BACKUP="${mbr_backup}"
	LANG=C sfdisk --no-reread "${DISK}" --force \
		-O "${mbr_backup}" <"${new_out}" >"${change_out}" 2>&1
	ret=$?
	[ $ret -eq 0 ] || RESTORE_FUNC="${restore_func}"

	if [ $ret -eq 0 ]; then
		debug 1 "resize of ${DISK} returned 0."
		if [ $VERBOSITY -gt 2 ]; then
			sed 's,^,| ,' "${change_out}" 1>&2
		fi
	elif $PT_UPDATE &&
		sfdisk_worked_but_blkrrpart_failed "$ret" "${change_out}"; then
		# if the command failed, but it looks like only because
		# the device was busy and we have pt_update, then go on
		debug 1 "sfdisk failed, but likely only because of blkrrpart"
	else
		error "attempt to resize ${DISK} failed. sfdisk output below:"
		sed 's,^,| ,' "${change_out}" 1>&2
		fail "failed to resize"
	fi

	rq pt_update pt_update "$DISK" "$PART" ||
		fail "pt_resize failed"

	RESTORE_FUNC=""

	changed "${change_info}"

	# dump_out looks something like:
	## partition table of /tmp/out.img
	#unit: sectors
	#
	#/tmp/out.img1 : start=        1, size=    48194, Id=83
	#/tmp/out.img2 : start=    48195, size=   963900, Id=83
	#/tmp/out.img3 : start=  1012095, size=   305235, Id=82
	#/tmp/out.img4 : start=  1317330, size=   771120, Id= 5
	#/tmp/out.img5 : start=  1317331, size=   642599, Id=83
	#/tmp/out.img6 : start=  1959931, size=    48194, Id=83
	#/tmp/out.img7 : start=  2008126, size=    80324, Id=83
}

gpt_restore() {
	sgdisk -l "${GPT_BACKUP}" "${DISK}"
}

resize_sgdisk() {
	GPT_BACKUP="${TEMP_D}/pt.backup"

	local pt_info="${TEMP_D}/pt.info"
	local pt_pretend="${TEMP_D}/pt.pretend"
	local pt_data="${TEMP_D}/pt.data"
	local out="${TEMP_D}/out"

	local dev="disk=${DISK} partition=${PART}"

	local pt_start pt_end pt_size last pt_max code guid name new_size
	local old new change_info sector_size

	# Dump the original partition information and details to disk. This is
	# used in case something goes wrong and human interaction is required
	# to revert any changes.
	rqe sgd_info sgdisk "--info=${PART}" --print "${DISK}" >"${pt_info}" ||
		fail "${dev}: failed to dump original sgdisk info"
	RESTORE_HUMAN="${pt_info}"

	sector_size=$(awk '$0 ~ /^Logical sector size:.*bytes/ { print $4 }' \
		"$pt_info") && [ -n "$sector_size" ] || {
		sector_size=512
		error "WARN: did not find sector size, assuming 512"
	}

	debug 1 "$dev: original sgdisk info:"
	debugcat 1 "${pt_info}"

	# Pretend to move the backup GPT header to the end of the disk and dump
	# the resulting partition information. We use this info to determine if
	# we have to resize the partition.
	rqe sgd_pretend sgdisk --pretend --move-second-header \
		--print "${DISK}" >"${pt_pretend}" ||
		fail "${dev}: failed to dump pretend sgdisk info"

	debug 1 "$dev: pretend sgdisk info"
	debugcat 1 "${pt_pretend}"

	# Extract the partition data from the pretend dump
	awk 'found { print } ; $1 == "Number" { found = 1 }' \
		"${pt_pretend}" >"${pt_data}" ||
		fail "${dev}: failed to parse pretend sgdisk info"

	# Get the start and end sectors of the partition to be grown
	pt_start=$(awk '$1 == '"${PART}"' { print $2 }' "${pt_data}") &&
		[ -n "${pt_start}" ] ||
		fail "${dev}: failed to get start sector"
	pt_end=$(awk '$1 == '"${PART}"' { print $3 }' "${pt_data}") &&
		[ -n "${pt_end}" ] ||
		fail "${dev}: failed to get end sector"
	# sgdisk start and end are inclusive.  start 2048 length 10 ends at 2057.
	pt_end=$((pt_end+1))
	pt_size="$((${pt_end} - ${pt_start}))"

	# Get the last usable sector
	last=$(awk '/last usable sector is/ { print $NF }' \
		"${pt_pretend}") && [ -n "${last}" ] ||
		fail "${dev}: failed to get last usable sector"

	# Find the minimal start sector that is >= pt_end
	pt_max=$(awk '{ if ($2 >= pt_end && $2 < min) { min = $2 } } END \
		{ print min }' min="${last}" pt_end="${pt_end}" \
		"${pt_data}") && [ -n "${pt_max}" ] ||
		fail "${dev}: failed to find max end sector"

	debug 1 "${dev}: pt_start=${pt_start} pt_end=${pt_end}" \
		"pt_size=${pt_size} pt_max=${pt_max} last=${last}"

	# Check if the partition can be grown
	[ "${pt_end}" -eq "${pt_max}" ] &&
		nochange "${dev}: size=${pt_size}, it cannot be grown"
	[ "$((${pt_end} + ${FUDGE}/${sector_size}))" -gt "${pt_max}" ] &&
		nochange "${dev}: could only be grown by" \
		"$((${pt_max} - ${pt_end})) [fudge=$((${FUDGE}/$sector_size))]"

	# The partition can be grown if we made it here. Get some more info
	# about it so we can do it properly.
	# FIXME: Do we care about the attribute flags?
	code=$(awk '/^Partition GUID code:/ { print $4 }' "${pt_info}")
	guid=$(awk '/^Partition unique GUID:/ { print $4 }' "${pt_info}")
	name=$(awk '/^Partition name:/ { gsub(/'"'"'/, "") ; \
		if (NF >= 3) print substr($0, index($0, $3)) }' "${pt_info}")
	[ -n "${code}" -a -n "${guid}" ] ||
		fail "${dev}: failed to parse sgdisk details"

	debug 1 "${dev}: code=${code} guid=${guid} name='${name}'"
	local wouldrun=""
	[ "$DRY_RUN" -ne 0 ] && wouldrun="would-run"

	# Calculate the new size of the partition
	new_size=$((${pt_max} - ${pt_start}))
	change_info="partition=${PART} start=${pt_start}"
	change_info="${change_info} old: size=${pt_size} end=${pt_end}"
	change_info="${change_info} new: size=${new_size} end=${pt_max}"

	# Backup the current partition table, we're about to modify it
	rq sgd_backup $wouldrun sgdisk "--backup=${GPT_BACKUP}" "${DISK}" ||
		fail "${dev}: failed to backup the partition table"

	# Modify the partition table. We do it all in one go (the order is
	# important!):
	#  - move the GPT backup header to the end of the disk
	#  - delete the partition
	#  - recreate the partition with the new size
	#  - set the partition code
	#  - set the partition GUID
	#  - set the partition name
	rq sgdisk_mod $wouldrun sgdisk --move-second-header "--delete=${PART}" \
		"--new=${PART}:${pt_start}:$((pt_max-1))" \
		"--typecode=${PART}:${code}" \
		"--partition-guid=${PART}:${guid}" \
		"--change-name=${PART}:${name}" "${DISK}" &&
		rq pt_update $wouldrun pt_update "$DISK" "$PART" || {
		RESTORE_FUNC=gpt_restore
		fail "${dev}: failed to repartition"
	}

	# Dry run
	[ "${DRY_RUN}" -ne 0 ] && change "${change_info}"

	changed "${change_info}"
}

kver_to_num() {
	local kver="$1" maj="" min="" mic="0"
	kver=${kver%%-*}
	maj=${kver%%.*}
	min=${kver#${maj}.}
	min=${min%%.*}
	mic=${kver#${maj}.${min}.}
	[ "$kver" = "$mic" ] && mic=0
	_RET=$(($maj*1000*1000+$min*1000+$mic))
}

kver_cmp() {
	local op="$2" n1="" n2=""
	kver_to_num "$1"
	n1="$_RET"
	kver_to_num "$3"
	n2="$_RET"
	[ $n1 $op $n2 ]
}

rq() {
	# runquieterror(label, command)
	# gobble stderr of a command unless it errors
	local label="$1" ret="" efile=""
	efile="$TEMP_D/$label.err"
	shift;

	local rlabel="running"
	[ "$1" = "would-run" ] && rlabel="would-run" && shift

	local cmd="" x=""
	for x in "$@"; do
		[ "${x#* }" != "$x" -o "${x#* \"}" != "$x" ] && x="'$x'"
		cmd="$cmd $x"
	done
	cmd=${cmd# }

	debug 2 "$rlabel[$label][$_capture]" "$cmd"
	[ "$rlabel" = "would-run" ] && return 0

	if [ "${_capture}" = "erronly" ]; then
		"$@" 2>"$TEMP_D/$label.err"
		ret=$?
	else
		"$@" >"$TEMP_D/$label.err" 2>&1
		ret=$?
	fi
	if [ $ret -ne 0 ]; then
		error "failed [$label:$ret]" "$@"
 		cat "$efile" 1>&2
	fi
	return $ret
}

rqe() {
	local _capture="erronly"
	rq "$@"
}

verify_ptupdate() {
	local input="$1" found="" reason="" kver=""

	# we can always satisfy 'off'
	if [ "$input" = "off" ]; then
 		_RET="false";
		return 0;
	fi

	if command -v partx >/dev/null 2>&1; then
		local out="" ret=0
		out=$(partx --help 2>&1)
		ret=$?
		if [ $ret -eq 0 ]; then
			echo "$out" | grep -q -- --update || {
				reason="partx has no '--update' flag in usage."
				found="off"
			}
		else
			reason="'partx --help' returned $ret. assuming it is old."
			found="off"
		fi
	else
		reason="no 'partx' command"
		found="off"
	fi

	if [ -z "$found" ]; then
		if [ "$(uname)" != "Linux" ]; then
			reason="Kernel is not Linux per uname."
			found="off"
		fi
	fi

	if [ -z "$found" ]; then
		kver=$(uname -r) || debug 1 "uname -r failed!"

		if ! kver_cmp "${kver-0.0.0}" -ge 3.8.0; then
			reason="Kernel '$kver' < 3.8.0."
			found="off"
		fi
	fi

	if [ -z "$found" ]; then
		_RET="true"
		return 0
	fi

	case "$input" in
		on) error "$reason"; return 1;;
		auto)
			_RET="false";
			debug 1 "partition update disabled: $reason"
			return 0;;
		force)
			_RET="true"
			error "WARNING: ptupdate forced on even though: $reason"
			return 0;;
	esac
	error "unknown input '$input'";
	return 1;
}

pt_update() {
	local dev="$1" part="$2" update="${3:-$PT_UPDATE}"
	if ! $update; then
		return 0
	fi
	# partx only works on block devices (do not run on file)
	[ -b "$dev" ] || return 0
	partx --update --nr "$part" "$dev"
}

has_cmd() {
	command -v "${1}" >/dev/null 2>&1
}

resize_sgdisk_gpt() {
	resize_sgdisk gpt
}

resize_sgdisk_dos() {
	fail "unable to resize dos label with sgdisk"
}

resize_sfdisk_gpt() {
	resize_sfdisk gpt
}

resize_sfdisk_dos() {
	resize_sfdisk dos
}

get_table_format() {
	local out="" disk="$1"
	if has_cmd blkid && out=$(blkid -o value -s PTTYPE "$disk") &&
		[ "$out" = "dos" -o "$out" = "gpt" ]; then
		_RET="$out"
		return
	fi
	_RET="dos"
	if [ ${SFDISK_VERSION} -lt ${SFDISK_2_26} ] &&
		out=$(sfdisk --id --force "$disk" 1 2>/dev/null); then
		if [ "$out" = "ee" ]; then
			_RET="gpt"
		else
			_RET="dos"
		fi
		return
	elif out=$(LANG=C sfdisk --list "$disk"); then
		out=$(echo "$out" | sed -e '/Disklabel type/!d' -e 's/.*: //')
		case "$out" in
			gpt|dos) _RET="$out";;
			*) error "WARN: unknown label $out";;
		esac
	fi
}

get_resizer() {
	local format="$1" user=${2:-"auto"}

	case "$user" in
		sgdisk) _RET="resize_sgdisk_$format"; return;;
		sfdisk) _RET="resize_sfdisk_$format"; return;;
		auto) :;;
		*) error "unexpected input: '$user'";;
	esac

	if [ "$format" = "dos" ]; then
		_RET="resize_sfdisk_dos"
		return 0
	fi

	if [ "${SFDISK_VERSION}" -ge ${SFDISK_V_WORKING_GPT} ]; then
		# sfdisk 2.26.2 works for resize but loses type (LP: #1474090)
		_RET="resize_sfdisk_gpt"
	elif has_cmd sgdisk; then
		_RET="resize_sgdisk_$format"
	else
		error "no tools available to resize disk with '$format'"
		return 1
	fi
	return 0
}

pt_update="auto"
resizer=${GROWPART_RESIZER:-"auto"}
while [ $# -ne 0 ]; do
	cur=${1}
	next=${2}
	case "$cur" in
		-h|--help)
			Usage
			exit 0
			;;
		--fudge)
			FUDGE=${next}
			shift
			;;
		-N|--dry-run)
			DRY_RUN=1
			;;
		-u|--update|--update=*)
			if [ "${cur#--update=}" != "$cur" ]; then
				next="${cur#--update=}"
			else
				shift
			fi
			case "$next" in
				off|auto|force|on) pt_update=$next;;
				*) fail "unknown --update option: $next";;
			esac
			;;
		-v|--verbose)
			VERBOSITY=$(($VERBOSITY+1))
			;;
		--)
			shift
			break
			;;
		-*)
			fail "unknown option ${cur}"
			;;
		*)
			if [ -z "${DISK}" ]; then
				DISK=${cur}
			else
				[ -z "${PART}" ] || fail "confused by arg ${cur}"
				PART=${cur}
			fi
			;;
	esac
	shift
done

[ -n "${DISK}" ] || bad_Usage "must supply disk and partition-number"
[ -n "${PART}" ] || bad_Usage "must supply partition-number"

has_cmd "sfdisk" || fail "sfdisk not found"
get_sfdisk_version || fail

[ -e "${DISK}" ] || fail "${DISK}: does not exist"

# If $DISK is a symlink, resolve it.
# This avoids problems due to varying partition device name formats
# (e.g. "1" for /dev/sda vs "-part1" for /dev/disk/by-id/name)
if [ -L "${DISK}" ]; then
	has_cmd readlink ||
		fail "${DISK} is a symlink, but 'readlink' command not available."
	real_disk=$(readlink -f "${DISK}") || fail "unable to resolve ${DISK}"
	debug 1 "${DISK} resolved to ${real_disk}"
	DISK=${real_disk}
fi

[ "${PART#*[!0-9]}" = "${PART}" ] || fail "partition-number must be a number"

verify_ptupdate "$pt_update" || fail
PT_UPDATE=$_RET

debug 1 "update-partition set to $PT_UPDATE"

mktemp_d && TEMP_D="${_RET}" || fail "failed to make temp dir"
trap cleanup 0 # EXIT - some shells may not like 'EXIT' but are ok with 0

# get the ID of the first partition to determine if it's MBR or GPT
get_table_format "$DISK" || fail
format=$_RET
get_resizer "$format" "$resizer" ||
	fail "failed to get a resizer for id '$id'"
resizer=$_RET

debug 1 "resizing $PART on $DISK using $resizer"
"$resizer"

# vi: ts=4 noexpandtab