GP-6399 Ensure we are not in headless mode for GUI launch. Headless apps should use headless config.

Ghidra/Debug/Debugger-isf/src/main/java/ghidra/dbg/isf/IsfServer.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -27,7 +27,7 @@ import ghidra.GhidraApplicationLayout;
 import ghidra.GhidraTestApplicationLayout;
 import ghidra.base.project.GhidraProject;
 import ghidra.framework.Application;
-import ghidra.framework.GhidraApplicationConfiguration;
+import ghidra.framework.HeadlessGhidraApplicationConfiguration;
 import ghidra.framework.data.OpenMode;
 import ghidra.framework.model.DomainFile;
 import ghidra.framework.model.ProjectData;
@@ -163,8 +163,8 @@ public class IsfServer extends Thread {
 	public static void main(String[] args) throws FileNotFoundException, IOException {
 		GhidraApplicationLayout layout =
 			new GhidraTestApplicationLayout(new File(AbstractGTest.getTestDirectoryPath()));
-		GhidraApplicationConfiguration config = new GhidraApplicationConfiguration();
-		config.setShowSplashScreen(false);
+		HeadlessGhidraApplicationConfiguration config =
+			new HeadlessGhidraApplicationConfiguration();
 		Application.initializeApplication(layout, config);
 
 		IsfServer server = new IsfServer(null, 54321);

Ghidra/Features/Base/src/main/java/ghidra/framework/GhidraApplicationConfiguration.java

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -15,6 +15,8 @@
  */
 package ghidra.framework;
 
+import java.awt.GraphicsEnvironment;
+
 import docking.DockingErrorDisplay;
 import docking.DockingWindowManager;
 import docking.framework.ApplicationInformationDisplayFactory;
@@ -37,6 +39,16 @@ public class GhidraApplicationConfiguration extends HeadlessGhidraApplicationCon
 	private static final String USER_AGREEMENT_PROPERTY_NAME = "USER_AGREEMENT";
 	private boolean showSplashScreen = true;
 
+	public GhidraApplicationConfiguration() {
+		if (GraphicsEnvironment.isHeadless()) {
+			System.err.println(
+				"ERROR: Unable to launch Ghidra GUI application in headless environment.");
+			System.err.println(
+				"If launching from a remote SSH shell, you must have an X11 compatible client with X11 forwarding enabled.");
+			System.exit(1);
+		}
+	}
+
 	@Override
 	public boolean isHeadless() {
 		return false;