burrow-pi-img/export-image/prerun.sh

#!/bin/bash -e

IMG_FILE="${STAGE_WORK_DIR}/${IMG_FILENAME}${IMG_SUFFIX}.img"

unmount_image "${IMG_FILE}"

rm -f "${IMG_FILE}"

rm -rf "${ROOTFS_DIR}"
mkdir -p "${ROOTFS_DIR}"

BOOT_SIZE=$(du --apparent-size -s "${EXPORT_ROOTFS_DIR}/boot" --block-size=1 | cut -f 1)
TOTAL_SIZE=$(du --apparent-size -s "${EXPORT_ROOTFS_DIR}" --exclude var/cache/apt/archives --block-size=1 | cut -f 1)

ROUND_SIZE="$((4 * 1024 * 1024))"
ROUNDED_ROOT_SECTOR=$(((2 * BOOT_SIZE + ROUND_SIZE) / ROUND_SIZE * ROUND_SIZE / 512 + 8192))
IMG_SIZE=$(((BOOT_SIZE + TOTAL_SIZE + (800 * 1024 * 1024) + ROUND_SIZE - 1) / ROUND_SIZE * ROUND_SIZE))

truncate -s "${IMG_SIZE}" "${IMG_FILE}"
fdisk -H 255 -S 63 "${IMG_FILE}" <<EOF
o
n


8192
+$((BOOT_SIZE * 2 /512))
p
t
c
n


${ROUNDED_ROOT_SECTOR}


p
w
EOF

PARTED_OUT=$(parted -sm "${IMG_FILE}" unit b print)
BOOT_OFFSET=$(echo "$PARTED_OUT" | grep -e '^1:' | cut -d':' -f 2 | tr -d B)
BOOT_LENGTH=$(echo "$PARTED_OUT" | grep -e '^1:' | cut -d':' -f 4 | tr -d B)

ROOT_OFFSET=$(echo "$PARTED_OUT" | grep -e '^2:' | cut -d':' -f 2 | tr -d B)
ROOT_LENGTH=$(echo "$PARTED_OUT" | grep -e '^2:' | cut -d':' -f 4 | tr -d B)

BOOT_DEV=$(losetup --show -f -o "${BOOT_OFFSET}" --sizelimit "${BOOT_LENGTH}" "${IMG_FILE}")
ROOT_DEV=$(losetup --show -f -o "${ROOT_OFFSET}" --sizelimit "${ROOT_LENGTH}" "${IMG_FILE}")
echo "/boot: offset $BOOT_OFFSET, length $BOOT_LENGTH"
echo "/:     offset $ROOT_OFFSET, length $ROOT_LENGTH"

ROOT_FEATURES="^huge_file"
for FEATURE in metadata_csum 64bit; do
	if grep -q "$FEATURE" /etc/mke2fs.conf; then
	    ROOT_FEATURES="^$FEATURE,$ROOT_FEATURES"
	fi
done
mkdosfs -n boot -F 32 -v "$BOOT_DEV" > /dev/null
mkfs.ext4 -L rootfs -O "$ROOT_FEATURES" "$ROOT_DEV" > /dev/null

mount -v "$ROOT_DEV" "${ROOTFS_DIR}" -t ext4
mkdir -p "${ROOTFS_DIR}/boot"
mount -v "$BOOT_DEV" "${ROOTFS_DIR}/boot" -t vfat

rsync -aHAXx --exclude /var/cache/apt/archives --exclude /boot "${EXPORT_ROOTFS_DIR}/" "${ROOTFS_DIR}/"
rsync -rtx "${EXPORT_ROOTFS_DIR}/boot/" "${ROOTFS_DIR}/boot/"