burrow-pi-img/scripts/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"
    kpartx -a $NBD_DEV
    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
,250MiB,b
,,83;
EOF
		sync
                kpartx -a $NBD_DEV
                mkdosfs -n boot -F 32 -v $MAP_BOOT_DEV
                mkfs.ext4 -L rootfs -O "^huge_file,^metadata_csum,^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 -a $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=$((800*1024*1024))
    PARTED_OUT=`parted -s -m "$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
    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

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

    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"
    umount "${MOUNTROOT}/boot" || exit 1
    umount "${MOUNTROOT}" || exit 1

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