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Attached is a patch against udev-008 to send out a D-BUS message when a
device node is added or removed.
Using D-BUS lingo, udev acquires the org.kernel.udev service and sends
out a NodeCreated or NodeDeleted signal on the
org.kernel.udev.NodeMonitor interface. Each signal carries two
parameters: the node in question and the corresponding sysfs path.
[Note: the D-BUS concepts of service, interface, object can be a bit
confusing at first glance]
An example program listening for these messages looks like this
#!/usr/bin/python
import dbus
import gtk
def udev_signal_received(dbus_iface, member, service, object_path, message):
[filename, sysfs_path] = message.get_args_list()
if member=='NodeCreated':
print 'Node %s created for %s'%(filename, sysfs_path)
elif member=='NodeDeleted':
print 'Node %s deleted for %s'%(filename, sysfs_path)
def main():
bus = dbus.Bus(dbus.Bus.TYPE_SYSTEM)
bus.add_signal_receiver(udev_signal_received,
'org.kernel.udev.NodeMonitor', # interface
'org.kernel.udev', # service
'/org/kernel/udev/NodeMonitor') # object
gtk.mainloop()
if __name__ == '__main__':
main()
and this is the output when hot-plugging some usb-storage.
[david@laptop udev-008]$ ~/node_monitor.py
Node /udev/sda created for /block/sda
Node /udev/sda1 created for /block/sda/sda1
Node /udev/sda1 deleted for /block/sda/sda1
Node /udev/sda deleted for /block/sda
The patch requires D-BUS 0.20 or later while the python example program
requires D-BUS from CVS as I only recently applied a patch against the
python bindings.
24 lines
791 B
Plaintext
24 lines
791 B
Plaintext
<!DOCTYPE busconfig PUBLIC
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"-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
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"http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
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<busconfig>
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<!-- This configuration file specifies the required security policies
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for udev to work. -->
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<!-- Only root can own the udev service and only root can use the
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org.kernel.udev.NodeMonitor interface to send signals -->
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<policy user="root">
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<allow own="org.kernel.udev"/>
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<allow send_interface="org.kernel.udev.NodeMonitor"/>
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</policy>
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<!-- Allow anyone to listen to the org.kernel.udev.NodeMonitor interface
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for messages send from the owner of the org.kernel.udev service -->
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<policy context="default">
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<allow receive_interface="org.kernel.udev.NodeMonitor"/>
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</policy>
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</busconfig>
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