Writing PolicyKit applications in Python without D-Bus

I'm always happy when more libraries get Python bindings, and today I've been especially excited by the fact that GObject introspection support for PolicyKit has finally appeared in Natty repositories. Basically it means, that PolicyKit is now accessible from Python through a native API without direct D-Bus communication. I've tried to port the querying example from PolicyKit manual and it did work!

The Python example below is an almost line-by-line port of the original, but it should give you a basic idea on how to use the API for your own scripts.

#! /usr/bin/env python

import sys, os
from gi.repository import GObject, Gio, Polkit

def on_tensec_timeout(loop):
  print("Ten seconds have passed. Now exiting.")
  loop.quit()
  return False

def check_authorization_cb(authority, res, loop):
    try:
        result = authority.check_authorization_finish(res)
        if result.get_is_authorized():
            print("Authorized")
        elif result.get_is_challenge():
            print("Challenge")
        else:
            print("Not authorized")
    except GObject.GError as error:
         print("Error checking authorization: %s" % error.message)
        
    print("Authorization check has been cancelled "
          "and the dialog should now be hidden.\n"
          "This process will exit in ten seconds.")
    GObject.timeout_add(10000, on_tensec_timeout, loop)

def do_cancel(cancellable):
    print("Timer has expired; cancelling authorization check")
    cancellable.cancel()
    return False

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("usage: %s <action_id>" % sys.argv[0])
        sys.exit(1)
    action_id = sys.argv[1]

    mainloop = GObject.MainLoop()
    authority = Polkit.Authority.get()
    subject = Polkit.UnixProcess.new(os.getppid())

    cancellable = Gio.Cancellable()
    GObject.timeout_add(10 * 1000, do_cancel, cancellable)

    authority.check_authorization(subject,
        action_id, #"org.freedesktop.policykit.exec",
        None,
        Polkit.CheckAuthorizationFlags.ALLOW_USER_INTERACTION,
        cancellable,
        check_authorization_cb,
        mainloop)

    mainloop.run()

In order to run this example, make sure you have the gir1.2-polkit-1.0 package installed and provide an action in the command line, for example:

./polkit-test org.freedesktop.policykit.exec

I suppose, the API is still a little rough on the edges, but it's already usable and I'm going to try it for an upcoming D-Bus service in indicator-cpufreq. Looks like it's perfect time to start moving things to GObject introspection already.

Hello Planet Ubuntu!

Greetings to all the Planet readers! I've become an Ubuntu member today (or was it yesterday in Americas?), and this is my first post on Planet Ubuntu.

My name's Artem Popov and I am an active member of the Russian Ubuntu Translators team. Sometimes, I also help with packaging / bugs and I intend to become a MOTU in the future.

Ubuntu is my favourite distribution for a long time now, because I believe it has many things done right from the very start. Contributing to Ubuntu is a great opportunity to gain new experience and it's always a pleasure to work with such a rocking community.

For now, I am going to continue my work on translations and packages with the MOTU team, but maybe I shall try some other ways of helping out. Fortunately, there are plenty of them!