# Copyright (C) 2015 Canonical Ltd. # # Author: Ryan Harper <ryan.harper@canonical.com> # # This file is part of cloud-init. See LICENSE file for license information. def compose_udev_equality(key, value): """Return a udev comparison clause, like `ACTION=="add"`.""" assert key == key.upper() return '%s=="%s"' % (key, value) def compose_udev_attr_equality(attribute, value): """Return a udev attribute comparison clause, like `ATTR{type}=="1"`.""" assert attribute == attribute.lower() return 'ATTR{%s}=="%s"' % (attribute, value) def compose_udev_setting(key, value): """Return a udev assignment clause, like `NAME="eth0"`.""" assert key == key.upper() return '%s="%s"' % (key, value) def generate_udev_rule(interface, mac, driver=None): """Return a udev rule to set the name of network interface with `mac`. The rule ends up as a single line looking something like: SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}="ff:ee:dd:cc:bb:aa", NAME="eth0" """ if not driver: driver = "?*" rule = ", ".join( [ compose_udev_equality("SUBSYSTEM", "net"), compose_udev_equality("ACTION", "add"), compose_udev_equality("DRIVERS", driver), compose_udev_attr_equality("address", mac), compose_udev_setting("NAME", interface), ] ) return "%s\n" % rule