#!/bin/sh

MOUNT=""
LODEV=""
CHS=""
TEMP_D=""
MP=""

cleanup() {
        [ -n "$MOUNT" ] && umount $MOUNT
        rm -Rf "$TEMP_D"
}
getchs() {
	sfdisk "${rootdisk}" --show-pt-geometry > "${TEMP_D}/chs" 2>${TEMP_D}/chs.err &&
		read _devc cyl _word1 heads _word2 sectors _word3 < "${TEMP_D}/chs" &&
		_RET="-C $cyl -H $heads -S $sectors" ||
		fail "failed to get CHS from ${rootdisk}"
}
debug() {
	echo "==== start: ${1} ===="
	grep " ${rootdisk##*/}" /proc/partitions
	getchs && echo "CHS: $_RET"
	echo "==== end: ${1} ===="
}
fail() { [ $# -eq 0 ] || error "$@"; debug "fail"; exit 1; }
error() { echo "$@" 1>&2; }

rootdisk=${1}

[ -n "$rootdisk" -a -b "$rootdisk" ] ||
	{ error "Please give block device (ie /dev/vdb).  WARNING! this is destructive!"; exit 1; } 

TEMP_D=$(mktemp -d "${TMPDIR:-/tmp/${0##*/}.XXXXXX}")
trap cleanup EXIT

MP="${TEMP_D}/mp"
mkdir "$MP"


## set up the disk to have some partition table with space at end

tmp="${TEMP_D}/show-part.out"
err="$TEMP_D/err"

getchs && _RET=$CHS || 
	fail "failed to get CHS from ${rootdisk}"

end=$((($cyl*$heads*$sectors)/2))
error "sfdisk'ing to 1 partition, half size. 2048,$end,L"
echo "2048,$((($cyl*$heads*$sectors)/2)),L" |
	sfdisk --force $CHS -uS "$rootdisk" >"${err}" 2>&1||
	fail "failed to create sfdisk.\n$(cat ${err})"

udevadm settle --timeout 30
#sleep 3
debug "sfdisk'd"

partnum=1
part="${rootdisk}${partnum}"

error "creating fs on $part"
mkfs -q -t ext4 "$part" ||
	fail "failed mkfs $part"

udevadm settle --timeout 30

error "mounting $part at $MP"
mount -o ro "$part" "$MP" && MOUNT=${part} || fail "failed to mount ${part}"

debug "mounted"

out=$(growpart --dry-run "${rootdisk}" "${partnum}" 2>"$err") ||
	fail "failed to growpart dry-run: ${out}...\n$(cat ${err})"

error "growpart says: ${out}"
case "${out}" in
	CHANGE:*) :;;
	*) fail "Huh? no resize needed?: ${out}";
esac

error "umounting ${part}"
out=$(umount "$part" 2>&1) && MOUNT="" ||
	fail "failed to umount $part: ${out}"

error "growing part ${rootdisk} 1"
##out=$(growpart "${rootdisk}" "${partnum}" 2>&1) ||
#out=$(growpart --dry-run "${rootdisk}" "${partnum}" 2>"$err") ||
#	fail "failed to growpart dry-run: ${out}"

if out=$(growpart "${rootdisk}" "${partnum}" 2>"${err}"); then
	case "$out" in
		CHANGED:*) echo "GROWROOT: $out";;
		NOCHANGE:*) fail "GROWROOT: WARNING: expected to grow partition, but did not: ${out}\n$(cat ${err})";;
		*) fail "GROWROOT: unexpected output: ${out}\n$(cat ${err})"
	esac
else
	#fail "GROWROOT: WARNING: resize failed: $out\n$(cat ${err})"
	fail "GROWROOT: WARNING: resize failed: $out"
fi

## now, it would 
# udevadm settle --timeout ${ROOTDELAY:-30}
# wait-for-root "${ROOT}" ${ROOTDELAY:-30}
# mount ${roflag} ${FSTYPE:+-t ${FSTYPE} }${ROOTFLAGS} ${ROOT} ${rootmnt}