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authordavid@fubar.dk <david@fubar.dk>2003-12-08 09:19:19 -0800
committerGreg KH <gregkh@suse.de>2005-04-26 21:13:06 -0700
commit5aebfbcb62614fc2bf2b1579d62e3fe272c6751a (patch)
treeafe2093652343ee02e95880d25cf3b3e48779c74 /udev.c
parent3d150dfb28efbaf0b25f154fb8955c47d606c3d5 (diff)
[PATCH] D-BUS patch for udev-008
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.
Diffstat (limited to 'udev.c')
-rw-r--r--udev.c64
1 files changed, 64 insertions, 0 deletions
diff --git a/udev.c b/udev.c
index bf18a568ea..67b86e5916 100644
--- a/udev.c
+++ b/udev.c
@@ -63,6 +63,60 @@ static inline char *get_seqnum(void)
return seqnum;
}
+#ifdef USE_DBUS
+
+/** Global variable for the connection the to system message bus or #NULL
+ * if we cannot connect or acquire the org.kernel.udev service
+ */
+DBusConnection* sysbus_connection;
+
+/** Disconnect from the system message bus */
+static void sysbus_disconnect()
+{
+ if (sysbus_connection == NULL)
+ return;
+
+ dbus_connection_disconnect(sysbus_connection);
+ sysbus_connection = NULL;
+}
+
+/** Connect to the system message bus */
+static void sysbus_connect()
+{
+ DBusError error;
+
+ /* Connect to a well-known bus instance, the system bus */
+ dbus_error_init(&error);
+ sysbus_connection = dbus_bus_get(DBUS_BUS_SYSTEM, &error);
+ if (sysbus_connection == NULL) {
+ dbg("cannot connect to system message bus, error %s: %s",
+ error.name, error.message);
+ dbus_error_free(&error);
+ return;
+ }
+
+ /* Acquire the org.kernel.udev service such that listeners
+ * know that the message is really from us and not from a
+ * random attacker. See the file udev_sysbus_policy.conf for
+ * details.
+ *
+ * Note that a service can have multiple owners (though there
+ * is a concept of a primary owner for reception of messages)
+ * so no race is introduced if two copies of udev is running
+ * at the same time.
+ */
+ dbus_bus_acquire_service(sysbus_connection, "org.kernel.udev", 0,
+ &error);
+ if (dbus_error_is_set(&error)) {
+ printf("cannot acquire org.kernel.udev service, error %s: %s'",
+ error.name, error.message);
+ sysbus_disconnect();
+ return;
+ }
+}
+
+#endif /* USE_DBUS */
+
int main(int argc, char **argv, char **envp)
{
char *action;
@@ -111,6 +165,11 @@ int main(int argc, char **argv, char **envp)
/* initialize our configuration */
udev_init_config();
+#ifdef USE_DBUS
+ /* connect to the system message bus */
+ sysbus_connect();
+#endif /* USE_DBUS */
+
/* initialize udev database */
retval = udevdb_init(UDEVDB_DEFAULT);
if (retval != 0) {
@@ -133,6 +192,11 @@ int main(int argc, char **argv, char **envp)
}
udevdb_exit();
+#ifdef USE_DBUS
+ /* disconnect from the system message bus */
+ sysbus_disconnect();
+#endif /* USE_DBUS */
+
exit:
return retval;
}