Bug 528414 (swtWaylandLauncher) Part 1 SWT GDBus implementation.

General purpose GDBus interface for converting GDBus calls to SWT
events.

Adding SWT.OpenDocument event handler.

To verify:
1) Open child eclipse.
2) Create files:  /tmp/hi and /tmp/hithere
3) Run command:
gdbus call --session --dest org.eclipse.swt --object-path
/org/eclipse/swt --method org.eclipse.swt.FileOpen
"['/tmp/hi','/tmp/there']"

The two files 'hi' and 'hithere' open in the child eclipse.

- If you open two (or more) Eclipse instances, the most recently
  opened Eclipse will receive gdbus call.
- If you close the 2nd eclipse, the previous (first) eclipse receives
  gdbus calls again.

Future improvement:
  The most-recently *focused* eclipse should receive gdbus call.

Bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=528414
Change-Id: Ib1fbbb09b74de4025611f68813ca53e6c62250b7
Signed-off-by: Leo Ufimtsev <lufimtse@redhat.com>

4 files changed, 409 insertions, 5 deletions

diff --git a/bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk/OS.java b/bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk/OS.java
index 09c5a4a856..3ee5f4dc0b 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk/OS.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk/OS.java
@@ -108,12 +108,14 @@ public class OS extends C {
 
 	// Bug 519124
 	static {
-		String swt_lib_versions = getEnvironmentalVariable ("SWT_LIB_VERSIONS"); // Note, this is read in multiple places.
+		String swt_lib_versions = getEnvironmentalVariable (OS.SWT_LIB_VERSIONS); // Note, this is read in multiple places.
 		if (swt_lib_versions != null && swt_lib_versions.equals("1")) {
 			System.out.println("SWT_LIB_Gtk:"+gtk_major_version()+"."+gtk_minor_version()+"."+gtk_micro_version());
 		}
 	}
 
+	public static final String SWT_LIB_VERSIONS = "SWT_LIB_VERSIONS";
+
 	public static String getEnvironmentalVariable (String envVarName) {
 		String envVarValue = null;
 		long /*int*/ ptr = C.getenv(ascii(envVarName));
@@ -573,13 +575,18 @@ public class OS extends C {
 	/**
 	 * DBus Data types as defined by:
 	 * https://dbus.freedesktop.org/doc/dbus-specification.html#idm423
+	 * If using these, make sure they're properly handled in all GDBus code. Only some of these are supported by some GDBus classes.
 	 * @category gdbus */
 	public static final String DBUS_TYPE_BYTE = "y"; // 8 bit, unsigned int.
 	/** @category gdbus */
 	public static final String DBUS_TYPE_BOOLEAN = "b";
 	/** @category gdbus */
+	public static final String DBUS_TYPE_ARRAY = "a";
+	/** @category gdbus */
 	public static final String DBUS_TYPE_STRING = "s";
 	/** @category gdbus */
+	public static final String DBUS_TYPE_STRING_ARRAY = "as";
+	/** @category gdbus */
 	public static final String DBUS_TYPE_DOUBLE = "d";
 	/** @category gdbus */
 	public static final String DBUS_TYPE_STRUCT = "r"; // Not used by Dbus, but implemented by GDBus.
@@ -597,6 +604,8 @@ public class OS extends C {
 	/** @category gdbus */
 	public static final byte[] G_VARIANT_TYPE_BOOLEAN = ascii(DBUS_TYPE_BOOLEAN);
 	/** @category gdbus */
+	public static final byte[] G_VARIANT_TYPE_STRING_ARRAY = ascii(DBUS_TYPE_STRING_ARRAY);
+	/** @category gdbus */
 	public static final byte[] G_VARIANT_TYPE_STRING = ascii(DBUS_TYPE_STRING);
 	/** @category gdbus */
 	public static final byte[] G_VARIANT_TYPE_DOUBLE = ascii(DBUS_TYPE_DOUBLE);
diff --git a/bundles/org.eclipse.swt/Eclipse SWT WebKit/gtk/org/eclipse/swt/internal/webkit/WebKitGTK.java b/bundles/org.eclipse.swt/Eclipse SWT WebKit/gtk/org/eclipse/swt/internal/webkit/WebKitGTK.java
index 7f3e23dbfe..d8a8912168 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT WebKit/gtk/org/eclipse/swt/internal/webkit/WebKitGTK.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT WebKit/gtk/org/eclipse/swt/internal/webkit/WebKitGTK.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2017 IBM Corporation and others. All rights reserved.
+ * Copyright (c) 2000, 2018 IBM Corporation and others. All rights reserved.
  * The contents of this file are made available under the terms
  * of the GNU Lesser General Public License (LGPL) Version 2.1 that
  * accompanies this distribution (lgpl-v21.txt).  The LGPL is also
@@ -29,7 +29,7 @@ public class WebKitGTK extends C {
 	 * Internal version of "Webkit glue code", used mainly during webkit2 port.
 	 * Used to make it easier to support users on bugzilla. Updated by hand.
 	 */
-	public static final String swtWebkitGlueCodeVersion = " SWT Glue code version: 53.0";
+	public static final String swtWebkitGlueCodeVersion = " SWT Glue code version: 54.0";
 	public static final String swtWebkitGlueCodeVersionInfo = " info: +BrowserFunction/GDBus, +WebkitExtension Folder versioning, +WebKitExtension OSGI support, +setUrl(..postData..), -setCookie(), -getCookie +mouseDown/Focus";
 
 
@@ -55,7 +55,7 @@ public class WebKitGTK extends C {
 			WEBKIT1 = !WEBKIT2;
 		}
 
-		String swt_lib_versions = OS.getEnvironmentalVariable ("SWT_LIB_VERSIONS"); // Note, this is read in multiple places.
+		String swt_lib_versions = OS.getEnvironmentalVariable (OS.SWT_LIB_VERSIONS); // Note, this is read in multiple places.
 		if (swt_lib_versions != null && swt_lib_versions.equals("1")) {
 			if (WEBKIT1) {
 				System.out.println("SWT_LIB  Webkit1   Webkitgtk:"+ webkit_major_version() +"."+ webkit_minor_version() + "." + webkit_micro_version() + "  (webkitgtk < 2.5 is Webkit1)");
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/internal/GDBus.java b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/internal/GDBus.java
new file mode 100644
index 0000000000..21bbf2f99c
--- /dev/null
+++ b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/internal/GDBus.java
@@ -0,0 +1,366 @@
+/*******************************************************************************
+ * Copyright (c) 2018 Red Hat and others. All rights reserved.
+ * The contents of this file are made available under the terms
+ * of the GNU Lesser General Public License (LGPL) Version 2.1 that
+ * accompanies this distribution (lgpl-v21.txt).  The LGPL is also
+ * available at http://www.gnu.org/licenses/lgpl.html.  If the version
+ * of the LGPL at http://www.gnu.org is different to the version of
+ * the LGPL accompanying this distribution and there is any conflict
+ * between the two license versions, the terms of the LGPL accompanying
+ * this distribution shall govern.
+ *
+ * Contributors:
+ *     Red Hat - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.swt.internal;
+
+import java.util.*;
+import java.util.function.*;
+
+import org.eclipse.swt.*;
+import org.eclipse.swt.internal.gtk.*;
+
+/**
+ * General purpose DBus interface for SWT to interact with the operating system and vice versa.
+ * (See also WebkitGDBus for the webkit specific gdbus interface).
+ *
+ * This implementation uses GDBus (Gnome DBus) to implement the DBus interface.
+ *
+ * It can be reached via:
+ * 		gdbus call --session --dest org.eclipse.swt --object-path /org/eclipse/swt --method org.eclipse.swt.YOUR_METHOD YOUR_ARGS
+ * where YOUR_ARGS can be something like  "MyString"  or  "['/tmp/myFile', '/tmp/myFile2']" etc..
+
+ * For hygiene purposes, GVariant/GDBus native types/values should *never* leave this class. Convert on the way in/out.
+ *
+ * Technical notes:
+ *  - Concurrent gdbus names can co-exist. (i.e, multiple session names in single proc).
+ *    Meaning if you don't like org.eclipse.swt, you can add more session names.
+ *  - This implementation is only a small subset of GDBus.
+ *    E.g not all types are translated and not functionality implemented. Add them as you need them.
+ *
+ * @category gdbus
+ */
+public class GDBus {
+
+	public static class GDBusMethod {
+		final private String name;
+		final private Function<Object[], Object[]> userFunction;
+		final private String methodArgsXmlSignature;
+
+		/**
+		 * Create a method that GDBus will listen to.
+		 *
+		 * @param name of the method. It will be part of 'org.eclipse.swt.NAME'
+		 * @param inputArgs   2D array pair of Strings :  (DBUS_TYPE_*, argument_name). Where argument_name is only so that it's seen by command line by user.
+		 * @param outputArgs  Same as inputArgs, but for returning values.
+		 * @param userFunction  A Function<Object[],Object[]>, that you would like to run when the user calls the method over gdbus.
+		 */
+		public GDBusMethod(String name, String [][] inputArgs, String [][] outputArgs, Function<Object[], Object[]> userFunction) {
+			this.name = name;
+			this.userFunction = userFunction;
+			StringBuilder gdbBusArgsXml = new StringBuilder();
+			for (String [] dataType : inputArgs) {
+				gdbBusArgsXml.append("     <arg type='" + dataType[0] + "' name='" + dataType[1] + "' direction='in'/>\n");
+			}
+			for (String [] dataType : outputArgs) { // I haven't tested output args, but should work if types get converted properly.
+				gdbBusArgsXml.append("     <arg type='" + dataType[0] + "' name='" + dataType[1] + "' direction='out'/>\n");
+			}
+			methodArgsXmlSignature = gdbBusArgsXml.toString();
+		}
+
+		private String getName() {
+			return name;
+		}
+
+		private Function<Object[], Object[]> getUserFunction() {
+			return userFunction;
+		}
+
+		private String getMethodArgsXmlSignature() {
+			return methodArgsXmlSignature;
+		}
+	}
+
+	public static void init (GDBusMethod[] methods) {
+		if (!initialized)
+			initialized = true;
+		else
+			return;
+
+		if (methods == null || methods.length == 0) {
+			System.err.println("SWT Error, no gdbus methods to initialize.");
+			return;
+		}
+
+		gdbusMethods = Arrays.asList(methods);
+
+		int owner_id = OS.g_bus_own_name(OS.G_BUS_TYPE_SESSION,
+				Converter.javaStringToCString(DBUS_SERVICE_NAME),
+				OS.G_BUS_NAME_OWNER_FLAGS_REPLACE | OS.G_BUS_NAME_OWNER_FLAGS_ALLOW_REPLACEMENT, // Allow name to be used by other eclipse instances.
+				onBusAcquired.getAddress(),
+				onNameAcquired.getAddress(), // name_acquired_handler
+				onNameLost.getAddress(), // name_lost_handler
+				0, // user_data
+				0); // user_data_free_func
+
+		if (owner_id == 0) {
+			System.err.println("SWT GDBus: Failed to aquire bus name: " + DBUS_SERVICE_NAME);
+		}
+	}
+
+	private static boolean initialized;
+	private static List<GDBusMethod> gdbusMethods;
+
+	private static final String DBUS_SERVICE_NAME = "org.eclipse.swt";
+	private static final String DBUS_OBJECT_NAME  = "/org/eclipse/swt";
+	private static final String INTERFACE_NAME    = "org.eclipse.swt";
+
+	private static Callback onBusAcquired;
+	private static Callback onNameAcquired;
+	private static Callback onNameLost;
+	private static Callback handleMethod;
+
+	static {
+		onBusAcquired = new Callback (GDBus.class, "onBusAcquired", 3); //$NON-NLS-1$
+		if (onBusAcquired.getAddress () == 0) SWT.error (SWT.ERROR_NO_MORE_CALLBACKS);
+
+		onNameAcquired = new Callback (GDBus.class, "onNameAcquired", 3); //$NON-NLS-1$
+		if (onNameAcquired.getAddress () == 0) SWT.error (SWT.ERROR_NO_MORE_CALLBACKS);
+
+		onNameLost = new Callback (GDBus.class, "onNameLost", 3); //$NON-NLS-1$
+		if (onNameLost.getAddress () == 0) SWT.error (SWT.ERROR_NO_MORE_CALLBACKS);
+
+		handleMethod = new Callback (GDBus.class, "handleMethod", 8); //$NON-NLS-1$
+		if (handleMethod.getAddress () == 0) SWT.error (SWT.ERROR_NO_MORE_CALLBACKS);
+
+		String swt_lib_versions = OS.getEnvironmentalVariable (OS.SWT_LIB_VERSIONS); // Note, this is read in multiple places. //leotask move string to a constant in OS.java
+		if (swt_lib_versions != null && swt_lib_versions.equals("1")) {
+			System.out.println("SWT_LIB GDbus implementation v1.");
+		}
+	}
+
+	static void teardown_gdbus() {
+		// Currently GDBus is persistent.
+		// If ever needed, gdbus can be disposed via:
+		// g_bus_unown_name (owner_id);					// owner_id would need to be made global
+		// g_dbus_node_info_unref (gdBusNodeInfo); // introspection_data Would need to be made global
+	}
+
+	/**
+	 * @return void. (No return value actually returned to OS. Just SWT mechanism dicates 'long' is returned.
+	 */
+	@SuppressWarnings("unused") // Callback only called directly by JNI.
+	private static long /*int*/ onBusAcquired (long /*int*/ gDBusConnection, long /*int*/ const_gchar_name, long /*int*/ user_data) {
+		long /*int*/ gdBusNodeInfo;
+
+		{ // Generate and parse DBus XML interface.
+			StringBuilder dbus_introspection_xml = new StringBuilder();
+			dbus_introspection_xml.append("<node><interface name='" + INTERFACE_NAME + "'>\n");
+			for (GDBusMethod method : gdbusMethods) {
+
+				dbus_introspection_xml.append("  <method name='" + method.name + "'>\n");
+				dbus_introspection_xml.append("   " + method.getMethodArgsXmlSignature() + "\n");
+				dbus_introspection_xml.append("  </method>\n");
+			}
+			dbus_introspection_xml.append("</interface></node>");
+
+			long /*int*/ [] error = new long /*int*/ [1];
+			gdBusNodeInfo = OS.g_dbus_node_info_new_for_xml(Converter.javaStringToCString(dbus_introspection_xml.toString()), error);
+			if (gdBusNodeInfo == 0 || error[0] != 0) {
+				System.err.println("SWT GDBus: Failed to get introspection data");
+			}
+			assert gdBusNodeInfo != 0 : "SWT GDBus: introspection data should not be 0";
+		}
+
+		{ // Register object
+			long /*int*/ [] error = new long /*int*/ [1];
+			long /*int*/ interface_info = OS.g_dbus_node_info_lookup_interface(gdBusNodeInfo, Converter.javaStringToCString(INTERFACE_NAME));
+			long /*int*/ vtable [] = { handleMethod.getAddress(), 0, 0 };
+			OS.g_dbus_connection_register_object(
+					gDBusConnection,
+					Converter.javaStringToCString(DBUS_OBJECT_NAME),
+					interface_info,
+					vtable,
+					0, // user_data
+					0, // user_data_free_func
+					error);
+			if (error[0] != 0) {
+				System.err.println("SWT GDBus: Failed to register object: " + DBUS_OBJECT_NAME);
+				return 0;
+			}
+		}
+
+		// Developer note:
+		// To verify that a gdbus interface is regisetered on the gdbus, you can use the 'gdbus' utility.
+		// e.g:
+		// gdbus introspect --session --dest org.eclipse  <Press TAB KEY>    // it should expand to something like:  (uniqueID might be appended at the end).
+		// gdbus introspect --session --dest org.eclipse.swt     			 // you can then get object info like:
+		// gdbus introspect --session --dest org.eclipse.swt --object-path /org/eclipse/swt ... etc
+
+		return 0; // Actual callback is void.
+	}
+
+
+	@SuppressWarnings("unused") // Callback Only called directly by JNI.
+	private static long /*int*/ onNameAcquired (long /*int*/ connection, long /*int*/ name, long /*int*/ user_data) {
+		// Currently not used, but can be used if acquring the gdbus name should trigger something to load.
+		return 0;
+	}
+
+	@SuppressWarnings("unused") // Callback Only called directly by JNI.
+	private static long /*int*/ onNameLost (long /*int*/ connection, long /*int*/ name, long /*int*/ user_data) {
+		System.err.println("SWT GDBus.java: Lost GDBus name. Maybe stolen?");
+		return 0;
+	}
+
+
+	/**
+	 * This is called when a client calls one of the GDBus methods.
+	 *
+	 * Developer note:
+	 * This method can be reached directly from GDBus cmd utility:
+	 * 	gdbus call --session --dest org.eclipse.swt --object-path /org/eclipse/swt --method org.eclipse.swt.<your method>
+	 * Tip: Use tab-completion.
+	 *
+	 * @param connection 	GDBusConnection
+	 * @param sender 		const gchar
+	 * @param object_path	const gchar
+	 * @param interface_name const gchar
+	 * @param method_name    const gchar
+	 * @param gvar_parameters	 GVariant
+	 * @param invocation     GDBusMethodInvocation
+	 * @param user_data      gpointer
+	 * @return
+	 */
+	@SuppressWarnings("unused") // Callback only called directly by JNI.
+	private static long /*int*/ handleMethod (
+			long /*int*/ connection, long /*int*/ sender,
+			long /*int*/ object_path, long /*int*/ interface_name,
+			long /*int*/ method_name, long /*int*/ gvar_parameters,
+			long /*int*/ invocation, long /*int*/ user_data) {
+
+		long /*int*/ resultGVariant = 0;
+		try {
+			String java_method_name = Converter.cCharPtrToJavaString(method_name, false);
+
+			for (GDBusMethod gdbusMethod : gdbusMethods) {
+				if (gdbusMethod.getName().equals(java_method_name)) {
+					Object [] args = convertGVariantToJava(gvar_parameters);
+					Object [] returnVal = gdbusMethod.getUserFunction().apply(args); // Return value currently not used. Can be added/implemented if required.
+					resultGVariant = convertJavaToGVariant(returnVal);
+					break;
+				}
+			}
+		} catch (Exception e) {
+			System.err.println("SWT GDBUS ERROR: Error in handling method.");
+		} finally {
+			// - GDBus method should always return to prevent caller from hanging.
+			// - Note, result must be a tuple. (or null..).
+
+			OS.g_dbus_method_invocation_return_value(invocation, resultGVariant);
+		}
+		return 0; // void return value.
+	}
+
+	/**
+	 * Converts the given GVariant(s) to Java Object(s).
+	 * If GVariant is not an array, this returns an Object[] array with one element.
+	 *
+	 * Only subset of types is currently supported, add type(s) as/when you need them.
+	 * For inspiration, see WebkitGDBus.java:convert..()
+	 *
+	 * @param gVariant a pointer to the native GVariant
+	 */
+	private static Object[] convertGVariantToJava(long /*int*/ gVariant) {
+		Object retVal = convertGVariantToJavaHelper(gVariant);
+		if (retVal instanceof Object[]) {
+			return (Object[]) retVal;
+		} else {
+			System.err.println("SWT GDBus Error converting arguments : Expecting object array, received Object.");
+			return null;
+		}
+	}
+
+	private static Object convertGVariantToJavaHelper(long /*int*/ gVariant){
+		// - Developer note:
+		//   When instantiating GDBus dynamically (as we do),
+		//   GDBus's 'Parameters' is _always_ a tuple of stuff.
+		//   E.g If you pass it only a single argument, then you will have a tuple with one object (s).
+		//   As such, '1) convert specific types' is only reached, at the earliest
+		//   on the 2nd invocation of this recursive function.
+		// - Note, tuples '()' are not the same as arrays 'a'. They're treated in different ways.
+
+		// 1) Convert specific types. (non-array).
+		if (OS.g_variant_is_of_type(gVariant, OS.G_VARIANT_TYPE_STRING)){
+			return Converter.cCharPtrToJavaString(OS.g_variant_get_string(gVariant, null), false);
+		}
+
+		// <add your primitive types>
+
+		//2) Handle struct of defined types. (Sort of like arrays, but note, tuples!=array).
+		if (OS.g_variant_is_of_type(gVariant, OS.G_VARIANT_TYPE_TUPLE)) {
+			int length = (int)OS.g_variant_n_children (gVariant);
+			Object[] result = new Object[length];
+			for (int i = 0; i < length; i++) {
+				result[i] = convertGVariantToJavaHelper (OS.g_variant_get_child_value(gVariant, i));
+			}
+			return result;
+		}
+
+		// 2 b) Handle an array of Strings. Same as above, except type is String.
+		if (OS.g_variant_is_of_type(gVariant, OS.G_VARIANT_TYPE_STRING_ARRAY)) {
+			int length = (int)OS.g_variant_n_children (gVariant);
+			String[] result = new String[length];
+			for (int i = 0; i < length; i++) {
+				result[i] = (String) convertGVariantToJavaHelper (OS.g_variant_get_child_value(gVariant, i));
+			}
+			return result;
+		}
+
+		String typeString = Converter.cCharPtrToJavaString(OS.g_variant_get_type_string(gVariant), false);
+		SWT.error (SWT.ERROR_INVALID_ARGUMENT, new Throwable("SWT GDBus: Unhandled variant type " + typeString ));
+		return null;
+	}
+
+	/**
+	 * Converts the given Java Object to a GVariant * representation.
+	 * (Only subset of types is currently supported).
+	 *
+	 * We assume that input Object may contain invalid types.
+	 *
+	 * @return pointer GVariant *
+	 */
+	private static long /*int*/ convertJavaToGVariant(Object javaObject) throws SWTException {
+		if (javaObject == null) {
+			return 0;
+		}
+
+		if (javaObject instanceof String) {
+			return OS.g_variant_new_string (Converter.javaStringToCString((String) javaObject));
+		}
+
+		// Add your types here.
+
+		// Dangers:
+		// Null values and empty arrays can cause problems.
+		//   - DBus doesn't have notion of 'null'.
+		//   - DBus doesn't support empty arrays.
+		// If needed, see workaround implemented in WebkitGDBus.java
+
+		if (javaObject instanceof Object[]) {
+			Object[] arrayValue = (Object[]) javaObject;
+			int length = arrayValue.length;
+
+			long /*int*/ variants[] = new long /*int*/[length];
+			for (int i = 0; i < length; i++) {
+				variants[i] = convertJavaToGVariant(arrayValue[i]);
+			}
+			return OS.g_variant_new_tuple(variants, length);
+		}
+
+		System.err.println("SWT GDbus: Invalid object being returned to caller: " + javaObject.toString());
+		throw new SWTException(SWT.ERROR_INVALID_ARGUMENT, "Given object is not valid: " + javaObject.toString());
+	}
+
+
+}
\ No newline at end of file
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Display.java b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Display.java
index dd79d22315..4a1c936285 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Display.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Display.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2017 IBM Corporation and others.
+ * Copyright (c) 2000, 2018 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -20,6 +20,7 @@ import java.util.regex.Pattern;
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.internal.*;
+import org.eclipse.swt.internal.GDBus.*;
 import org.eclipse.swt.internal.cairo.*;
 import org.eclipse.swt.internal.gtk.*;
 
@@ -1103,6 +1104,31 @@ void createDisplay (DeviceData data) {
 	keysChangedProc = keysChangedCallback.getAddress ();
 	if (keysChangedProc == 0) error (SWT.ERROR_NO_MORE_CALLBACKS);
 	OS.g_signal_connect (OS.gdk_keymap_get_default (), OS.keys_changed, keysChangedProc, 0);
+
+
+	{ // GDBus
+
+		// Handle files passed  to Eclipse via GDBus. (e.g from Equinox launcher).
+		// For example, this call can be reached via:
+		// gdbus call --session --dest org.eclipse.swt --object-path /org/eclipse/swt --method org.eclipse.swt.FileOpen "['/tmp/hi','/tmp/there']"
+		// In a child eclipse, this will open the files in a new editor.
+		// This is reached by equinox launcher from eclipseGtk.c. Look for "g_dbus_proxy_call_sync"
+		GDBusMethod fileOpenMethod = new GDBusMethod(
+				"FileOpen",
+				new String [][] {{OS.DBUS_TYPE_STRING_ARRAY,"FileNameArray"}},
+				new String [0][0],
+				(args) -> {
+					String[] fileNames = (String[]) args[0]; // Arg 1 is an arraay of strings.
+					for (int i = 0; i < fileNames.length; i++) {
+						Event event = new Event ();
+						event.text = fileNames[i];
+						sendEvent (SWT.OpenDocument, event);
+					}
+					return null;
+				});
+		GDBusMethod[] methods = {fileOpenMethod};
+		GDBus.init(methods);
+	}
 }
 
 /**
@@ -5686,6 +5712,9 @@ long /*int*/ signalProc (long /*int*/ gobject, long /*int*/ arg1, long /*int*/ u
 			settingsChanged = true;
 			break;
 		case PROPERTY_NOTIFY:
+
+			// Bug 528414 This whole mechanism is to be removed.
+			// Files passed by changing a window property. Uses X, which doesn't work on wayland.
 			GdkEventProperty gdkEvent = new GdkEventProperty ();
 			OS.memmove (gdkEvent, arg1);
 			if (gdkEvent.type == OS.GDK_PROPERTY_NOTIFY) {