Closed snowsky closed 3 years ago
hypfvieh
commented
3 years ago Sample code to demonstrate the issue will also be helpful. Without knowning what you are doing in your code it is hard to see if something is wrong.
3 messages are send, because every application which uses DBus must first register at DBus doing some sort of handshake (that's why you see the 'Hello' message). This server will answer to this message and then will do whatever it is supposed to do.
snowsky
commented
3 years ago @hypfvieh Thanks for the reply, my codes is quite simple which is to send a signal to logind interface as below:
try {
DBusConnection conn = DBusConnection.getConnection(DBusConnection.DBusBusType.SYSTEM);
DBusSignal signalToSend = new DBusSignal(null, "/", "org.freedesktop.login1.Manager", "Reboot", null, 1);
conn.sendMessage(signalToSend);
} catch (DBusException e) {
e.printStackTrace();
}"Reboot" signal got a boolean argument. I am not sure if I used it correctly. I also tried other signals like "CanReboot" which got no argument but it hangs at the same message, NameAcquired.
Thanks,
hypfvieh
commented
3 years ago 
This is not the way to do it.
The LoginManager does not expect signals for the operations you mentioned (see: documention of systemd-logind) or use d-feet to look through the possible methods/signals/properties of an exported DBus object.
Reboot and canReboot are methods in the Manager object (org.freedesktop.login1.Manager), so you first have to create the Java interface for this and then you can gather a instance of org.freedesktop.login1.Manager from DBus. On this object you can call canReboot and Reboot.
For creation of the interface you may try to use org.freedesktop.dbus.utils.generator.InterfaceCodeGeneratorwhich is part of dbus-java-utils.
The resulting code would look like this: ` try (DBusConnection sysConn = DBusConnection.getConnection(DBusBusType.SYSTEM)) { Manager mgr = sysConn.getRemoteObject("org.freedesktop.login1", "/org/freedesktop/login1", org.freedesktop.login1.Manager.class);
System.out.println("Reboot allowed: " + mgr.CanReboot());
System.out.println("PowerOff allowed: " + mgr.CanPowerOff());
}
}`The results should be 'yes' and 'yes' if it is allows to reboot/poweroff the device.
The result type of the CanXXX methods are String (not boolean), and will return 'yes' or 'no' (again see documention).
I also added sample code to my sandbox repository for this case, see here and here.
snowsky
commented
3 years ago Thanks @hypfvieh for the details, really appreciate that. Let me close the issue 👍
snowsky
commented
3 years ago @hypfvieh, I got some errors while using the version 3.2.4. I guess you may need to deploy a new version 3.3.0 to maven repo. :)
hypfvieh
commented
3 years ago If you want to use my generated sources, you have to use 3.3.0 of dbus-java because it contains some new types and annotations. If you create the interface files yourself using dbus-java-utils 3.2.4 it will also work with the older version.
snowsky
commented
3 years ago Thanks, what will be the release plan for version 3.3.0? I looked around in the repo but didn't find an example to use dbus-java-utils for the interface. I copied your java files and it worked. I believe there must be a simple way to define the interface lol
hypfvieh
commented
3 years ago easiest way to execute the generator is to checkout the sources of 3.2.4 and use maven to run the util. Building the commandline manually is pretty ugly due to the many dependencies... See also: https://hypfvieh.github.io/dbus-java/code-generation.html
Hi there, I'm trying to send a message to the system interface, for example, "org.freedesktop.login1.Manager.Reboot" to reboot the box. It is seen that there are 3 messages sent and it hangs at the message/signal
NameAcquired. I am trying to understand why there are 3 messages sent and how I can send thru the last message. Please let me know if this is a known issue. Thanks.