# Source code for bleak.backends.bluezdbus.utils

    import sys
    from typing import TYPE_CHECKING

    if TYPE_CHECKING:
        if sys.platform != "linux":
            assert False, "This backend is only available on Linux"

    import os
    from typing import Optional

    from dbus_fast.auth import AuthExternal
    from dbus_fast.constants import MessageType
    from dbus_fast.message import Message

    from bleak.exc import BleakDBusError, BleakError

    def assert_reply(reply: Message) -> None:
        """Checks that a D-Bus message is a valid reply.

        Raises:
            BleakDBusError: if the message type is ``MessageType.ERROR``
            AssertionError: if the message type is not ``MessageType.METHOD_RETURN``
        """
        if reply.message_type == MessageType.ERROR:
            assert reply.error_name
            raise BleakDBusError(reply.error_name, reply.body)
        assert reply.message_type == MessageType.METHOD_RETURN

    def extract_service_handle_from_path(path: str) -> int:
        try:
            return int(path[-4:], 16)
        except Exception as e:
            raise BleakError(f"Could not parse service handle from path: {path}") from e

    def device_path_from_characteristic_path(characteristic_path: str) -> str:
        """
        Scrape the device path from a D-Bus characteristic path.

        Args:
            characteristic_path: The D-Bus object path of the characteristic.

        Returns:
            A D-Bus object path of the device.
        """
        # /org/bluez/hci1/dev_FA_23_9D_AA_45_46/service000c/char000d
        return characteristic_path[:-21]

    def get_dbus_authenticator() -> Optional[AuthExternal]:
        uid = None
        try:
            uid = int(os.environ.get("BLEAK_DBUS_AUTH_UID", ""))
        except ValueError:
            pass

        auth = None
        if uid is not None:
            auth = AuthExternal(uid=uid)

        return auth