#!/bin/bash
###############################################################################
# GLOBALS
#

# flag file containing pids of running instances for concurrency checks
declare -rg OPENSLX_DISK_FLAG="/tmp/openslx.disk"
# file that will contain the name of the device used for the /tmp partition
# - label 'OPENSLX_TMP' in GPT / type '0x44' in MBR
declare -rg OPENSLX_TMP_MARKER="/tmp/openslx.disk.tmp"
# file that will contain the name of the device used for storing qcow2
# - label 'OPENSLX_SYS' in GPT / type '0x46' in MBR
declare -rg OPENSLX_SYS_MARKER="/tmp/openslx.disk.sys"
# mount point for system partition
declare -rg OPENSLX_SYS_MOUNT="/opt/openslx/system"

#
# END GLOBALS
###############################################################################

###############################################################################
# FUNCTION DEFINITIONS
#
# helper to mount the OPENSLX_SYS partition to /opt/openslx/system
# Usage: mount_sys_part <path_to_sys_partition>
mount_sys_part() {
	if [ ! -b "$1" ]; then
		warn "($$) Refusing to mount '$1' as its not a block device!"
		return 1
	fi

	local OPENSLX_SYS_DEVICE="$1"
	mkdir -p ${OPENSLX_SYS_MOUNT}
	if ! mount -t auto "${OPENSLX_SYS_DEVICE}" "${OPENSLX_SYS_MOUNT}"; then
		warn "($$) Mounting '${OPENSLX_SYS_DEVICE}' to '${OPENSLX_SYS_MOUNT}' failed."
		return 1
	fi
	return 0

}
#
# generic helper to format the given partition with the given filesystem or
# from the prefdefined list of xfs, ext4, ...
# Usage: format_disk <dev> <fs>
#  e.g.  format_disk /dev/sda1 xfs
format_disk () {
	local TARGET_DEVICE="$1"
	local fslist="xfs ext4"
	# if we have a second arguments, its the filesystem of choice
	local fs
	[ $# -ge 2 ] && fslist="$2"
	for fs in $fslist ; do
		unset found
		local MKFS="$(busybox which mkfs.$fs)"
		if [ -n $MKFS ]; then
			found=yes
			case "mkfs.$fs" in
				mkfs.xfs)   fopt="-fq"  ;;
				mkfs.ext4)  fopt="-Fq"  ;;
			esac
			info "($$) Formatting $TARGET_DEVICE as $fs"
			return $(${MKFS} ${fopt} "${TARGET_DEVICE}")
		fi
		[ -n "$found" ] && break
	done
	# still here? then we didn't find a proper formatter...
	warn "($$) Could not format $PART_DEV as $fs."
	return 1
}

#
# END FUNCTION DEFINITIONS
###############################################################################

###############################################################################
# MAIN CODE
#

command -v warn >/dev/null || . /lib/dracut-lib.sh

# let check the arguments
if [ "$#" -ne 2 ]; then
	warn "($$) '$0' need 2 arguments: '$0 [OPENSLX_SYS|OPENSLX_TMP] <dev_path>'"
	exit 1
fi
# $1 sane?
if [ "x$1" != "xOPENSLX_SYS" ] && [ "x$1" != "xOPENSLX_TMP" ]; then
	warn "($$) First arg needs to be either 'OPENSLX_SYS' or 'OPENSLX_TMP', given: $1"
	exit 1
fi
# $2 sane?
if [ ! -b "/dev/$2" ]; then
	warn "($$) Second arg appears not to be a block device!"
	exit 1
fi

# ok all seems well, set the arguments
PART_TYPE="$1"
PART_DEV="/dev/$2"

unset OPENSLX_TMP_DEVICE
unset OPENSLX_SYS_DEVICE

# lets check if we are already running
INSTANCES="$(grep "$PART_TYPE" "$OPENSLX_DISK_FLAG" | busybox wc -l)"
if [ "$INSTANCES" -ge 1 ]; then
	# uhoh we are not alone! Need to check
	# if the other instance actually did its job
	warn "($$) '$0' already running for $PART_TYPE on $PART_DEV... checking state."
	# here two/three cases depending on which PART_TYPE we are
	# currently processing.
	for timeout in 1 1 2; do
		# always give the other instance time to finish
		# but only check 3 times overall
		sleep $timeout
		case "$PART_TYPE" in
			OPENSLX_TMP)
				# was the tmp partition marker created with a device?
				if [ ! -f "${OPENSLX_TMP_MARKER}" ]; then
					info "($$) Invalid state: no marker for $PART_TYPE"
					continue
				fi
				# it was, is it a valid block device?
				OPENSLX_TMP_DEVICE="$(cat ${OPENSLX_TMP_MARKER})"
				if [ -z $OPENSLX_TMP_DEVICE -o ! -b $OPENSLX_TMP_DEVICE ]; then
					info "($$) Invalid state: no for device $OPENSLX_TMP_DEVICE"
					continue
				fi
				# its detected, its a block device and as mounting is
				# done later, we can not check for more at this point
				info "($$) Valid state for $OPENSLX_TMP_DEVICE as $PART_TYPE"
				exit 0
				;;
			OPENSLX_SYS)
				# was the system partition marker created with a device?
				if [ ! -f "${OPENSLX_SYS_MARKER}" ]; then
					info "($$) Invalid state: no marker for $PART_TYPE"
					continue
				fi
				# it was, is it a valid block device?
				OPENSLX_SYS_DEVICE="$(cat ${OPENSLX_SYS_MARKER})"
				if [ -z $OPENSLX_SYS_DEVICE -o ! -b $OPENSLX_SYS_DEVICE ]; then
					info "($$) Invalid state: no for device $OPENSLX_SYS_DEVICE"
					continue
				fi
				# its detected, its a block device, is it mounted?
				if mount | grep -qE "^$OPENSLX_SYS_DEVICE\ on $OPENSLX_SYS_MOUNT"; then
					info "($$) Valid state for $OPENSLX_SYS_DEVICE as $PART_TYPE"
					exit 0
				fi
				# if its not mounted, we want to keep on, so no exit!
				;;
			*)
				# weird case which should never happen
				warn "($$) If you see this, then $0 was called with a bad PART_TYPE: $@"
				continue
				;;
		esac
	done
	warn "($$) Timeout reached!"
	warn "($$) '$PART_TYPE' was found but not device was associated to it!"
fi

# We write our pid to $OPENSLX_DISK_FLAG in order to make sure
# we are the only instance of this script running.
info "($$) Processing: $PART_TYPE -> $PART_DEV ($$)"
echo "$PART_TYPE.$$" >> "$OPENSLX_DISK_FLAG"

# if we are still here, then we can go on and process the partition
if [ "$PART_TYPE" = "OPENSLX_TMP" ]; then
	# always format /tmp partition
	if ! format_disk "${PART_DEV}" xfs; then
		# error while formatting, cleanup
		warn "($$) Error formatting $PART_DEV ... removing $$"
		sed -i "/^${PART_TYPE}\.$$/d" "${OPENSLX_DISK_FLAG}"
		exit 1
	fi
	info "($$) Using '$PART_DEV' as '$PART_TYPE'"
	# mark it for later: in pre-pivot we will check this file
	# and mount it as $NEWROOT/tmp
	echo "$PART_DEV" > "$OPENSLX_TMP_MARKER"
	# remove our pid from OPENSLX_DISK_FLAG
	sed -i "/^${PART_TYPE}\.$$/d" "${OPENSLX_DISK_FLAG}"
	exit 0
fi
if [ "$PART_TYPE" = "OPENSLX_SYS" ]; then
	# TODO make the formatting of the system partition configurable
	if ! format_disk "${PART_DEV}" xfs; then
		# error while formatting, cleanup
		warn "($$) Error formatting $PART_DEV ... removing $$"
		sed -i "/^${PART_TYPE}\.$$/d" "${OPENSLX_DISK_FLAG}"
		exit 1
	fi
	# mark it
	# mount it now, since qemu-nbd needs it asap!
	if mount_sys_part "$PART_DEV"; then
		# mount worked, mark it as done
		info "($$) Using '$PART_DEV' as '$PART_TYPE'"
		echo "$PART_DEV" > "$OPENSLX_SYS_MARKER"
		sed -i "/^${PART_TYPE}\.$$/d" "${OPENSLX_DISK_FLAG}"
		exit 0
	else
		warn "($$) 'mount_sys_part' failed in $0"
		sed -i "/^${PART_TYPE}\.$$/d" "${OPENSLX_DISK_FLAG}"
		exit 1
	fi
fi

#
# END MAIN CODE
###############################################################################