Check for occupied beacon

app/src/main/java/io/xpipe/app/launcher/LauncherCommand.java

@@ -132,6 +132,14 @@ public class LauncherCommand implements Callable<Integer> {
                             + " is already locked. Is another instance running?");
             OperationMode.halt(1);
         }
+
+        // If an instance is running as another user, we cannot connect to it as the xpipe_auth file is inaccessible
+        // Therefore the beacon client is not present.
+        // We still should check whether it is somehow occupied, otherwise beacon server startup will fail
+        if (BeaconClient.isOccupied(port)) {
+            TrackEvent.info("Another instance is already running on this port as another user. Quitting ...");
+            OperationMode.halt(1);
+        }
     }
 
     private XPipeDaemonMode getEffectiveMode() {

beacon/src/main/java/io/xpipe/beacon/BeaconClient.java

@@ -24,6 +24,15 @@ public class BeaconClient {
         this.port = port;
     }
 
+    public static boolean isOccupied(int port) {
+        var file = XPipeInstallation.getLocalBeaconAuthFile();
+        var reachable = BeaconServer.isReachable(port);
+        if (!Files.exists(file) && !reachable) {
+            return false;
+        }
+        return reachable;
+    }
+
     public static BeaconClient establishConnection(int port, BeaconClientInformation information) throws Exception {
         var client = new BeaconClient(port);
         var auth = Files.readString(XPipeInstallation.getLocalBeaconAuthFile());