growpart

#!/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 its within this many 512 byte sectors, dont bother
FUDGE=${GROWPART_FUDGE:-$((20*1024))}
TEMP_D=""
RESTORE_FUNC=""
RESTORE_HUMAN=""
VERBOSITY=0
DISK=""
PART=""
PT_UPDATE=false
DRY_RUN=0

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 ${RESTORE_FUNC} ; then
			error "***** Appears to have gone OK ****"
		else
			error "***** FAILED! or original partition table" \
				"looked like: ****"
			cat "${RESTORE_HUMAN}" 1>&2
		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', 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
}

mbr_restore() {
	sfdisk --no-reread "${DISK}" < "${MBR_BACKUP}"
}

sfdisk_worked_but_blkrrpart_failed() {
	local ret="$1" output="$2"
	# exit code found was just 1, but dont insist on that
	#[ $ret -eq 1 ] || return 1
	# Successfully wrote the new partition table
	grep -qi "Success.* wrote.* new.* partition" "$output" &&
		grep -qi "BLKRRPART: Device or resource busy" "$output"
	return
}

mbr_resize() {
	RESTORE_HUMAN="${TEMP_D}/recovery"
	MBR_BACKUP="${TEMP_D}/orig.save"

	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"
	# this file stores the first 446 bytes (avoid sfdisk bug from util-linux 2.26.1)
	local dd446=${TEMP_D}/dd_446.out

	local tot dpart
	local pt_start pt_size pt_end max_end new_size change_info

	tot=$(sfdisk -l ${DISK} | head -1 | awk '{print $7}')

	debug 1 "total size=${tot} sectors"
	rqe sfd_dump sfdisk --dump "${DISK}" \
		>"${dump_out}" ||
		fail "failed to dump sfdisk info for ${DISK}"

	{
		echo "## sfdisk --dump ${DISK}"
		cat "${dump_out}"
	}  >"${RESTORE_HUMAN}"
	[ $? -eq 0 ] || fail "failed to save sfdisk -d output"

	debugcat 1 "${RESTORE_HUMAN}"

	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 "${DISK}p${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

	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 = $4 } } END { printf("%s\n",min); }' \
		min=${tot} pt_end=${pt_end} "${dump_mod}") &&
		[ -n "${max_end}" ] ||
		fail "failed to get max_end for partition ${PART}"

	debug 1 "max_end=${max_end} tot=${tot} 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})) -gt ${max_end} ] &&
		nochange "partition ${PART} could only be grown by" \
		"$((${max_end}-${pt_end})) [fudge=${FUDGE}]"

	# 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},/${new_size},/" "${dump_out}" \
		>"${new_out}" ||
		fail "failed to change size in output"

	change_info="partition=${PART} start=${pt_start} old: size=${pt_size} end=${pt_end} 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

	# save the bootstrap code area to avoid sfdisk bug from util-linux 2.26.1 
	# https://bugzilla.redhat.com/show_bug.cgi?id=1211405
	dd if="${DISK}" of="${dd446}" bs=446 count=1
	LANG=C sfdisk --no-reread "${DISK}" --force \
		-O "${MBR_BACKUP}" <"${new_out}" >"${change_out}" 2>&1
	ret=$?
	# restore the bootstrap code area
	[ $ret -eq 0 ] && dd if="${dd446}" of="${DISK}" || RESTORE_FUNC="mbr_restore"

	if [ $ret -eq 0 ]; then
		:
	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}"
}

gpt_resize() {
	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
	
	# 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}" >"${pt_info}" ||
	RESTORE_HUMAN="${pt_info}"

	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"
	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} + ${FUDGE}))" -gt "${pt_max}" ] &&
		nochange "${dev}: could only be grown by" \
		"$((${pt_max} - ${pt_end})) [fudge=${FUDGE}]"

	# 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}'"

	# Calculate the new size of the partition
	new_size=$((${pt_max} - ${pt_start}))
	old="old: size=${pt_size},end=${pt_end}"
	new="new: size=${new_size},end=${pt_max}"
	change_info="${dev}: start=${pt_start} ${old} ${new}"
	
	# Dry run
	[ "${DRY_RUN}" -ne 0 ] && change "${change_info}"

	# Backup the current partition table, we're about to modify it
	rq sgd_backup 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 sgdisk --move-second-header "--delete=${PART}" \
		"--new=${PART}:${pt_start}:${pt_max}" \
		"--typecode=${PART}:${code}" \
		"--partition-guid=${PART}:${guid}" \
		"--change-name=${PART}:${name}" "${DISK}" &&
		rq pt_update pt_update "$DISK" "$PART" || {
		RESTORE_FUNC=gpt_restore
		fail "${dev}: failed to repartition"
	}

	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/$label.err"
	shift;
	debug 2 "running[$label][$_capture]" "$@"
	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
		partx --help | grep -q -- --update || {
			reason="partx has no '--update' flag in usage."
			found="off"
		}
	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 ! $update; then
		return 0
	fi
	partx --update "$part" "$dev"
}

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

pt_update="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"

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

[ "${PART#*[!0-9]}" = "${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 EXIT

# get the ID of the first partition to determine if it's MBR or GPT
id=$(sfdisk --id --force "${DISK}" 1 2>/dev/null) ||
	fail "unable to determine partition type"

if [ "${id}" = "ee" ] ; then
	has_cmd "sgdisk" || fail "GPT partition found but no sgdisk"
	debug 1 "found GPT partition table (id = ${id})"
	gpt_resize
else
	debug 1 "found MBR partition table (id = ${id})"
	mbr_resize
fi

# vi: ts=4 noexpandtab