path: root/builder/modules.d/dnbd3-rootfs/hooks/prepare-root-partition.sh

#!/usr/bin/env bash
type emergency_shell > /dev/null 2>&1 || source /lib/dracut-lib.sh
source /etc/openslx

export PATH="/usr/local/bin:$PATH"
export LD_LIBRARY_PATH="/usr/local/lib"


# hardcode dnbd device path
declare -rg _dnbd3_dev="/dev/dnbd0"

# all outputs are redirected to stderr, since this functions should
# only echo the path to the unpacked container to stdout.
container_unpack_xmount() {
    local in_device="$1"
    local out_path="/mnt/xmount"
    mkdir -p "$out_path"
    # check tools first
    if ! hash xmount systemd-preserve-process-marker; then
        warn "Missing xmount deps, will try raw..." 1>&2
    elif ! systemd-preserve-process-marker xmount \
            --in qemu "$in_device" \
            --out raw "$out_path" &>/dev/null; then
        warn "xmount call failed, assuming raw image." 1>&2
    else
        in_device="${out_path}/${_dnbd3_dev##*/}.dd"
    fi
    local out_device="$(losetup -f)"
    if ! losetup "$out_device" "$in_device" --partscan; then
        warn "Failed to attach '$in_device' to '$out_device'."
        return 1
    fi
    udevadm settle
    echo "$out_device"
}

container_unpack_losetup() {
    local in_device="$1"
    local out_device="$(losetup -f)"
    if ! losetup -r -t QCOW "$out_device" "$in_device" --partscan; then
        warn "Failed to attach '$in_device' to '$out_device'."
        return
    fi
    udevadm settle
    echo "$out_device"
}
# endregion

(
IFS=", "
for host in ${SLX_DNBD3_SERVERS} FAIL; do
    if [ "$host" = "FAIL" ]; then
        emergency_shell "Failed to connect '${SLX_DNBD3_IMAGE}' "\
            "${SLX_DNBD3_RID:+(revision: $SLX_DNBD3_RID)} "
            "from one of '$SLX_DNBD3_SERVERS' to '$_dnbd3_dev'."
    fi
    info "Trying host \"$host\"."
    if systemd-preserve-process-marker dnbd3-client \
        --host "$host" \
        --image "${SLX_DNBD3_IMAGE}" \
        --device "$_dnbd3_dev" \
        ${SLX_DNBD3_RID:+--rid "$SLX_DNBD3_RID"}; then
        break
    fi
done
)
# endregion
# region unpack dnbd3 image
[ -z "$SLX_QCOW_HANDLER" ] && SLX_QCOW_HANDLER="xmount"
if [ "$SLX_QCOW_HANDLER" = "xmount" ]; then
    read_only_device="$(container_unpack_xmount "$_dnbd3_dev")"
elif [ "$SLX_QCOW_HANDLER" = "kernel" ]; then
    read_only_device="$(container_unpack_losetup "$_dnbd3_dev")"
else
    warn "Unsupported QCOW handler: $SLX_QCOW_HANDLER"
fi

# Fail fast if unpacking dnbd3 image failed.
[ -z "$read_only_device" ] && exit 1

# endregion
# region find system partition within dnbd3 image
if [ -z "$SLX_SYSTEM_PARTITION_PREPARATION_SCRIPT" ]; then
    if [ -z "$SLX_SYSTEM_PARTITION_IDENTIFIER" ]; then
        # if empty use whole device
        read_only_partition="$read_only_device"
        true
    else
        read_only_partition="$(slx-tools dev_find_partitions \
            "$read_only_device" "$SLX_SYSTEM_PARTITION_IDENTIFIER")"
    fi
else
    eval "$SLX_SYSTEM_PARTITION_PREPARATION_SCRIPT"
fi
if [[ ! $? || -z "$read_only_partition" ]]; then
    warn "Failed to find unique device with identifier" \
        "\"${SLX_SYSTEM_PARTITION_IDENTIFIER}\"; matched devices:" \
        "\"${read_only_partition}\""
    exit 1
fi
info "Using read-only partition: $read_only_partition"
# endregion

# region add rw layer to dnbd3 image
# don't be fooled to think we are done, the next part is crucial
dmsetup-slx-device "$read_only_partition"
# endregion