USB devices UDev and D-BUS

Question

I am trying to get a list of currently plugged in USB devices in Ubuntu 10.10 and monitor changes that happen, like devices being plugged in or out using UDev and D-BUS. I'm fairly new to programming using D-BUS. I saw one example: Linux : How to detect is usb keyboard is plugged and unplugged only that one uses HAL and I know that HAL is deprecated. I found some working code, modified it a bit, only it doesn't work for any device only storage devices such as usb sticks, media players or cd-rom devices. I want the whole thing mice, keyboards, usb cameras chargers anything that is plugged in to the USB I want my program to know about it. This is basically what I have ( http://moserei.de/2010/01/08/accessing-devicekit-with-dbus-and-python.html ):

import dbus
import gobject
from dbus.mainloop.glib import DBusGMainLoop

def device_added_callback(device):
    print 'Device %s was added' % (device)

def device_changed_callback(device):
    print 'Device %s was changed' % (device)

#must be done before connecting to DBus
DBusGMainLoop(set_as_default=True)

bus = dbus.SystemBus()

proxy = bus.get_object("org.freedesktop.UDisks", 
                       "/org/freedesktop/UDisks")
iface = dbus.Interface(proxy, "org.freedesktop.UDisks.Device")

devices = iface.get_dbus_method('EnumerateDevices')()

print '%s' % (devices)

#addes two signal listeners
iface.connect_to_signal('DeviceAdded', device_added_callback)
iface.connect_to_signal('DeviceChanged', device_changed_callback)

#start the main loop
mainloop = gobject.MainLoop()
mainloop.run()

Any help would be apreciated. Thank you in advance, Calota Romeo

Maynord

For the future reference (I was looking for exactly this code, not a generic usb handler), you need to change: iface = dbus.Interface(proxy, "org.freedesktop.UDisks.Device") to iface = dbus.Interface(proxy, "org.freedesktop.UDisks") at least when udisks 1.0.4 is used. – Disfavor

Answer 1

The udisks D-Bus service, obviously, only reports disks.

Just monitor udev directly (through libudev, through pyudev).

import pyudev
context = pyudev.Context()
monitor = pyudev.Monitor.from_netlink(context)
observer = pyudev.pygtk.GUDevMonitorObserver(monitor)
observer.connect('device-added', device_added_callback)
observer.connect('device-changed', device_changed_callback)
monitor.enable_receiving()
mainloop = gobject.MainLoop()
mainloop.run()

Photocomposition

Thanks for the help I managed to get something working based on your answer. – Maynord

How would callback function actually look like? I don't find information on the parameters the device-added and device-changed signals pass to the callback. I want to see if a device with a specific idVendor and idProduct is connected and could use some help. Thanks in advance. – Bugbee

@Bugbee As listed on pyudev.glib, those two signals will invoke their callbacks with two arguments, the second of which is a device with attributes in device.attributes. – Photocomposition

I get AttributeError: 'module' object has no attribute 'pygtk'. Can you elaborate on this answer a little bit? Is it possible to get the drive UUID from this, so you can perform an action only when a specific drive is added? – Spruce

@Spruce pyudev.readthedocs.org/en/latest/api/… – Remus

Answer 2

This is what I use to list already plugged flash sticks. You can modify script to your needs

import dbus  
bus = dbus.SystemBus()

proxy = bus.get_object("org.freedesktop.Hal", "/org/freedesktop/Hal/Manager")
iface = dbus.Interface(proxy, "org.freedesktop.Hal.Manager")

devices = iface.GetAllDevices ()

for device in devices:
  try:
      proxy1 = bus.get_object("org.freedesktop.Hal", device)
      iface1 = dbus.Interface(proxy1, "org.freedesktop.Hal.Device")
      props = iface1.GetAllProperties()

      removable = iface1.GetProperty("storage.removable")
      usb = iface1.GetProperty("storage.bus")
      if usb== "usb":
        print "\n".join(("%s: %s" % (k, props[k]) for k in props)) # shows available properties
  except:
    pass

And this is what I use to see if any usb plugged :

#!/usr/bin/python
import dbus
import gobject

class DeviceAddedListener:
                def __init__(self):
                                self.bus = dbus.SystemBus()
                                self.hal_manager_obj = self.bus.get_object("org.freedesktop.Hal", "/org/freedesktop/Hal/Manager")
                                self.hal_manager = dbus.Interface(self.hal_manager_obj,"org.freedesktop.Hal.Manager")

                                self.hal_manager.connect_to_signal("DeviceAdded", self._filter) 

                def _filter(self, udi):
                                device_obj = self.bus.get_object ("org.freedesktop.Hal", udi)
                                device = dbus.Interface(device_obj, "org.freedesktop.Hal.Device")
                                self.do_something(device)

                def do_something(self, device):
                                try:

                                                usb = device.GetProperty("storage.bus")
                                                info = device.GetProperty("info.product")
                                                removable = device.GetProperty("storage.removable")
                                                print info
                                except:
                                                pass#blah blah


if __name__ == '__main__':
                from dbus.mainloop.glib import DBusGMainLoop
                DBusGMainLoop(set_as_default=True)
                loop = gobject.MainLoop()
                DeviceAddedListener()
                loop.run()

Here is the example of UDisks : python udisks - enumerating device information

Soubrette

Relies on HAL, which is deprecated and no longer present in the newest Linux distributions. – Photocomposition

@Photocomposition yes you are right. But I think using "UDisks" cannot be so different.@Calota I hope this works for you – Soubrette