qcow2_handling

#!/bin/bash

# QCOW2 Routines

export CURRENT_IMAGE
export CURRENT_MOUNTPOINT

export NBD_DEV
export MAP_BOOT_DEV
export MAP_ROOT_DEV

# set in build.sh
# should be fairly enough for the beginning
# overwrite here by uncommenting following lines
# BASE_QCOW2_SIZE=12G

# find and initialize free block device nodes
init_nbd() {
	modprobe nbd max_part=16
	if [ -z "${NBD_DEV}" ]; then
	for x in /sys/class/block/nbd* ; do
		S=`cat $x/size`
		if [ "$S" == "0" ] ; then
			NBD_DEV=/dev/$(basename $x)
			MAP_BOOT_DEV=/dev/mapper/$(basename $x)p1
			MAP_ROOT_DEV=/dev/mapper/$(basename $x)p2
			break
		fi
	done
	fi
}
export -f init_nbd

# connect image to block device
connect_blkdev() {
	init_nbd
	qemu-nbd --discard=unmap -c $NBD_DEV "$1"
	sync
	kpartx -as $NBD_DEV
	sync
	CURRENT_IMAGE="$1"
}
export -f connect_blkdev

# disconnect image from block device
disconnect_blkdev() {
	kpartx -d $NBD_DEV
	qemu-nbd -d $NBD_DEV
	NBD_DEV=
	MAP_BOOT_DEV=
	MAP_ROOT_DEV=
	CURRENT_IMAGE=
}
export -f disconnect_blkdev

# mount qcow2 image: mount_image <image file> <mountpoint>
mount_qimage() {
	connect_blkdev "$1"
	mount -v -t ext4 $MAP_ROOT_DEV "$2"
	mkdir -p "${ROOTFS_DIR}/boot"
	mount -v -t vfat $MAP_BOOT_DEV "$2/boot"
	CURRENT_MOUNTPOINT="$2"
}
export -f mount_qimage

# umount qcow2 image: umount_image <current mountpoint>
umount_qimage() {
	sync
	#umount "$1/boot"
	while mount | grep -q "$1"; do
		local LOCS
		LOCS=$(mount | grep "$1" | cut -f 3 -d ' ' | sort -r)
		for loc in $LOCS; do
			echo "$loc"
			while mountpoint -q "$loc" && ! umount "$loc"; do
				sleep 0.1
			done
		done
	done
	CURRENT_MOUNTPOINT=
	disconnect_blkdev
}
export -f umount_qimage

# create base image / backing image / mount image
load_qimage() {
	if [ -z "${CURRENT_MOUNTPOINT}" ]; then
		if [ ! -d "${ROOTFS_DIR}" ]; then
			mkdir -p "${ROOTFS_DIR}";
		fi

		if [ "${CLEAN}" = "1" ] && [ -f "${WORK_DIR}/image-${STAGE}.qcow2" ]; then
			rm -f "${WORK_DIR}/image-${STAGE}.qcow2";
		fi

		if [ ! -f "${WORK_DIR}/image-${STAGE}.qcow2" ]; then
			pushd ${WORK_DIR} > /dev/null
			init_nbd
			if [ -z "${PREV_STAGE}" ]; then
				echo "Creating base image: image-${STAGE}.qcow2"
				#  -o preallocation=falloc
				qemu-img create -f qcow2 image-${STAGE}.qcow2 $BASE_QCOW2_SIZE
				sync
				qemu-nbd --discard=unmap -c $NBD_DEV image-${STAGE}.qcow2
				sync
				sfdisk $NBD_DEV << EOF
4MiB,250MiB,c,*
254MiB,,83;
EOF
				sync
				kpartx -as $NBD_DEV
				mkdosfs -n boot -F 32 -s 4 -v $MAP_BOOT_DEV
				mkfs.ext4 -L rootfs -O "^huge_file,^64bit" $MAP_ROOT_DEV
				sync
			else
				if [ ! -f "${WORK_DIR}/image-${PREV_STAGE}.qcow2" ]; then
					exit 1;
				fi
				echo "Creating backing image: image-${STAGE}.qcow2 <- ${WORK_DIR}/image-${PREV_STAGE}.qcow2"
				qemu-img create -f qcow2 \
					-o backing_file=${WORK_DIR}/image-${PREV_STAGE}.qcow2 \
					${WORK_DIR}/image-${STAGE}.qcow2
				sync
				qemu-nbd --discard=unmap -c $NBD_DEV image-${STAGE}.qcow2
				sync
				kpartx -as $NBD_DEV
			fi

			mount -v -t ext4 $MAP_ROOT_DEV "${ROOTFS_DIR}"
			mkdir -p "${ROOTFS_DIR}/boot"
			mount -v -t vfat $MAP_BOOT_DEV "${ROOTFS_DIR}/boot"
			CURRENT_IMAGE=${WORK_DIR}/image-${STAGE}.qcow2
			CURRENT_MOUNTPOINT=${ROOTFS_DIR}
			popd > /dev/null
		else
			mount_qimage "${WORK_DIR}/image-${STAGE}.qcow2" "${ROOTFS_DIR}"
		fi
		echo "Current image in use: ${CURRENT_IMAGE} (MP: ${CURRENT_MOUNTPOINT})"
	fi
}
export -f load_qimage

# umount current image and refresh mount point env var
unload_qimage() {
	if [ ! -z "${CURRENT_MOUNTPOINT}" ]; then
		fstrim -v "${CURRENT_MOUNTPOINT}" || true
		umount_qimage "${CURRENT_MOUNTPOINT}"
	fi
}
export -f unload_qimage

# based on: https://github.com/SirLagz/RaspberryPi-ImgAutoSizer
# helper function for make_bootable_image, do not call directly
function resize_qcow2() {
	if [ -z "$CALL_FROM_MBI" ]; then
		echo "resize_qcow2: cannot be called directly, use make_bootable_image instead"
		return 1
	fi

	# ROOT_MARGIN=$((800*1024*1024))
	ROOT_MARGIN=$((1*1024*1024))
	PARTED_OUT=`parted -s -m "$NBD_DEV" unit B print`
	PART_NO=`echo "$PARTED_OUT" | grep ext4 | awk -F: ' { print $1 } '`
	PART_START=`echo "$PARTED_OUT" | grep ext4 | awk -F: ' { print substr($2,1,length($2)-1) } '`

	e2fsck -y -f $MAP_ROOT_DEV || true

	DATA_SIZE=`resize2fs -P $MAP_ROOT_DEV | awk -F': ' ' { print $2 } '`
	BLOCK_SIZE=$(dumpe2fs -h $MAP_ROOT_DEV | grep 'Block size' | awk -F': ' ' { print $2 }')
	BLOCK_SIZE=${BLOCK_SIZE// /}

	let DATA_SIZE=$DATA_SIZE+$ROOT_MARGIN/$BLOCK_SIZE
	resize2fs -p $MAP_ROOT_DEV $DATA_SIZE
	sleep 1

	let PART_NEW_SIZE=$DATA_SIZE*$BLOCK_SIZE
	let PART_NEW_END=$PART_START+$PART_NEW_SIZE
	ACT1=`parted -s "$NBD_DEV" rm 2`
	ACT2=`parted -s "$NBD_DEV" unit B mkpart primary $PART_START $PART_NEW_END`
	NEW_IMG_SIZE=`parted -s -m "$NBD_DEV" unit B print free | tail -1 | awk -F: ' { print substr($2,1,length($2)-1) } '`
}
export -f resize_qcow2

# create raw img from qcow2: make_bootable_image <in.qcow2> <out.img>
function make_bootable_image() {
    
	EXPORT_QCOW2="$1"
	EXPORT_IMAGE="$2"

	echo "Connect block device to source qcow2"
	connect_blkdev "${EXPORT_QCOW2}"

	echo "Resize fs and partition"
	CALL_FROM_MBI=1
	resize_qcow2
	sync
	CALL_FROM_MBI=

	echo "Disconnect block device"
	disconnect_blkdev

	if [ -z "$NEW_IMG_SIZE" ]; then
		echo "NEW_IMG_SIZE could not be calculated, cannot process image. Exit."
		exit 1
	fi

	echo "Shrinking qcow2 image"
	qemu-img resize --shrink "${EXPORT_QCOW2}" $NEW_IMG_SIZE
	sync

	echo "Convert qcow2 to raw image"
	qemu-img convert -f qcow2 -O raw "${EXPORT_QCOW2}" "${EXPORT_IMAGE}"
	sync

	echo "Get PARTUUIDs from image"
	IMGID="$(blkid -o value -s PTUUID "${EXPORT_IMAGE}")"

	BOOT_PARTUUID="${IMGID}-01"
	echo "Boot: $BOOT_PARTUUID"
	ROOT_PARTUUID="${IMGID}-02"
	echo "Root: $ROOT_PARTUUID"

	echo "Mount image"
	MOUNTROOT=${WORK_DIR}/tmpimage
	mkdir -p $MOUNTROOT

	MOUNTPT=$MOUNTROOT
	PARTITION=2
	mount "${EXPORT_IMAGE}" "$MOUNTPT" -o loop,offset=$[ `/sbin/sfdisk -d "${EXPORT_IMAGE}" | grep "start=" | head -n $PARTITION | tail -n1 | sed 's/.*start=[ ]*//' | sed 's/,.*//'` * 512 ],sizelimit=$[ `/sbin/sfdisk -d "${EXPORT_IMAGE}" | grep "start=" | head -n $PARTITION | tail -n1 | sed 's/.*size=[ ]*//' | sed 's/,.*//'` * 512 ] || exit 1

	MOUNTPT=$MOUNTROOT/boot
	PARTITION=1
	mount "${EXPORT_IMAGE}" "$MOUNTPT" -o loop,offset=$[ `/sbin/sfdisk -d "${EXPORT_IMAGE}" | grep "start=" | head -n $PARTITION | tail -n1 | sed 's/.*start=[ ]*//' | sed 's/,.*//'` * 512 ],sizelimit=$[ `/sbin/sfdisk -d "${EXPORT_IMAGE}" | grep "start=" | head -n $PARTITION | tail -n1 | sed 's/.*size=[ ]*//' | sed 's/,.*//'` * 512 ] || exit 1

	if [ ! -d "${MOUNTROOT}/root" ]; then
		echo "Image damaged or not mounted. Exit."
		exit 1
	fi

	echo "Setup PARTUUIDs"
	if [ ! -z "$BOOT_PARTUUID" ] && [ ! -z "$ROOT_PARTUUID" ]; then
		echo "Set UUIDs to make it bootable"
		sed -i "s/BOOTDEV/PARTUUID=${BOOT_PARTUUID}/" "${MOUNTROOT}/etc/fstab"
		sed -i "s/ROOTDEV/PARTUUID=${ROOT_PARTUUID}/" "${MOUNTROOT}/etc/fstab"
		sed -i "s/ROOTDEV/PARTUUID=${ROOT_PARTUUID}/" "${MOUNTROOT}/boot/cmdline.txt"
	fi

	echo "Umount image"
	sync
	umount "${MOUNTROOT}/boot" || exit 1
	umount "${MOUNTROOT}" || exit 1

	echo "Remove qcow2 export image"
	rm -f "${EXPORT_QCOW2}"
}
export -f make_bootable_image