Bug 567422 - [Win32][DND] Drag and Drop can crash if target keep
reference to COM object
The aggressive release of all COM objects after the drag/drop
operation is done can be problematic if the drop target keeps a
reference to one of the COM objects for later use. When the target later
tries to release (or access) the already disposed COM object a crash
from invalid memory access is likely.
Instead if should trust that the target will eventually release the
references it still holds.
For the case that the target will request the data again after DND is
finished the last requested data is cached. Note: sending a DragSetData
event before DragStart or after DragEnd is considered a bug.
Change-Id: I48e88a58e46111a3879e071d56abb79ac75114a9
Signed-off-by: Paul Pazderski <paul-eclipse@ppazderski.de>
diff --git a/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DragSource.java b/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DragSource.java
index 6ea7154..611a7a3 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DragSource.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/DragSource.java
@@ -1,5 +1,5 @@
/*******************************************************************************
- * Copyright (c) 2000, 2019 IBM Corporation and others.
+ * Copyright (c) 2000, 2020 IBM Corporation and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
@@ -11,6 +11,7 @@
* Contributors:
* IBM Corporation - initial API and implementation
* Lars Vogel <Lars.Vogel@vogella.com> - Bug 497807
+ * Paul Pazderski - Improved implementation of IDataObject for bug 549643, 549661 and 567422
*******************************************************************************/
package org.eclipse.swt.dnd;
@@ -114,9 +115,8 @@
long hwndDrag;
// ole interfaces
- COMObject iDropSource;
- COMObject iDataObject;
- int refCount;
+ COMIDropSource iDropSource;
+ COMIDataObject iDataObject;
//workaround - track the operation performed by the drop target for DragEnd event
int dataEffect = DND.DROP_NONE;
@@ -125,6 +125,213 @@
static final int CFSTR_PERFORMEDDROPEFFECT = Transfer.registerType("Performed DropEffect"); //$NON-NLS-1$
static final TCHAR WindowClass = new TCHAR (0, "#32770", true);
+ private class COMIDropSource extends COMObject {
+
+ private long refCount = 0;
+
+ /**
+ * Create a new IDropSource COM object. Object is created with one active
+ * reference. (see {@link #Release()})
+ */
+ public COMIDropSource() {
+ super(new int[]{2, 0, 0, 2, 1});
+ AddRef();
+ }
+
+ @Override
+ public long method0(long[] args) {return QueryInterface(this, args[0], args[1]);}
+ @Override
+ public long method1(long[] args) {return AddRef();}
+ @Override
+ public long method2(long[] args) {return Release();}
+ @Override
+ public long method3(long[] args) {return QueryContinueDrag((int)args[0], (int)args[1]);}
+ @Override
+ public long method4(long[] args) {return GiveFeedback((int)args[0]);}
+
+ public long AddRef() {
+ refCount++;
+ return refCount;
+ }
+
+ public long Release() {
+ refCount--;
+ if (refCount == 0) {
+ if (DragSource.this.iDropSource == this) {
+ DragSource.this.iDropSource = null;
+ }
+ this.dispose();
+ if (COM.FreeUnusedLibraries) {
+ COM.CoFreeUnusedLibraries();
+ }
+ }
+ return refCount;
+ }
+ }
+
+ private class COMIDataObject extends COMObject {
+ /*
+ * A SWT application is used to provide the data to drag in an event callback
+ * which is called while the DND operation is performed. However Windows expects
+ * the data to passed around in an object whose lifetime is managed through
+ * reference counting. The drop target can keep a reference on the IDataObject
+ * and even try to query the data long after the DND operation is finished. One
+ * such case is Windows Explorer when showing a Portal Device (see bug 549661).
+ * SWT does two things to support this case:
+ * 1. Implement reference counting as intended. I.e. do not force release the
+ * object after DND is finished but trust that all involved applications are
+ * able to count correctly and will release the object at some point.
+ * 2. Cache the data which was last transfered/generated from the DragSource
+ * to be able to send it again after the DND operation is finished.
+ */
+
+ private long refCount = 0;
+
+ private final Transfer[] transferAgents;
+
+ /**
+ * The most recent data send in a GetData request (or GetDataHere if
+ * implemented). Or from another perspective the data the application returned
+ * in the most recent {@link DND#DragSetData} event.
+ */
+ private Object lastData = null;
+
+ /**
+ * Create a new IDataObject COM object. Objects are created with one active
+ * reference. (see {@link #Release()})
+ *
+ * @param transferAgents should be the transfer agents which are set on
+ * DragSource at the time this object is created.
+ */
+ public COMIDataObject(Transfer[] transferAgents) {
+ super(new int[]{2, 0, 0, 2, 2, 1, 2, 3, 2, 4, 1, 1});
+ AddRef();
+ this.transferAgents = transferAgents;
+ }
+
+ @Override
+ public long method0(long[] args) {return QueryInterface(this, args[0], args[1]);}
+ @Override
+ public long method1(long[] args) {return AddRef();}
+ @Override
+ public long method2(long[] args) {return Release();}
+ @Override
+ public long method3(long[] args) {return GetData(args[0], args[1]);}
+ // method4 GetDataHere - not implemented
+ @Override
+ public long method5(long[] args) {return QueryGetData(transferAgents, args[0]);}
+ // method6 GetCanonicalFormatEtc - not implemented
+ @Override
+ public long method7(long[] args) {return SetData(args[0], args[1], (int)args[2]);}
+ @Override
+ public long method8(long[] args) {return EnumFormatEtc(transferAgents, (int)args[0], args[1]);}
+ // method9 DAdvise - not implemented
+ // method10 DUnadvise - not implemented
+ // method11 EnumDAdvise - not implemented
+
+ public long AddRef() {
+ refCount++;
+ return refCount;
+ }
+
+ public long Release() {
+ refCount--;
+ if (refCount == 0) {
+ if (DragSource.this.iDataObject == this) {
+ DragSource.this.iDataObject = null;
+ }
+ this.dispose();
+ if (COM.FreeUnusedLibraries) {
+ COM.CoFreeUnusedLibraries();
+ }
+ }
+ return refCount;
+ }
+
+ /**
+ * Check if this IDataObject is currently used in a DND operation.
+ *
+ * @return <code>true</true> if this object currently used for DND
+ */
+ private boolean isActive() {
+ return DragSource.this.iDataObject == this;
+ }
+
+ private int GetData(long pFormatetc, long pmedium) {
+ /* Called by a data consumer to obtain data from a source data object.
+ The GetData method renders the data described in the specified FORMATETC
+ structure and transfers it through the specified STGMEDIUM structure.
+ The caller then assumes responsibility for releasing the STGMEDIUM structure.
+ */
+ if (pFormatetc == 0 || pmedium == 0) return COM.E_INVALIDARG;
+
+ if (QueryGetData(transferAgents, pFormatetc) != COM.S_OK) return COM.DV_E_FORMATETC;
+
+ TransferData transferData = new TransferData();
+ transferData.formatetc = new FORMATETC();
+ COM.MoveMemory(transferData.formatetc, pFormatetc, FORMATETC.sizeof);
+ transferData.type = transferData.formatetc.cfFormat;
+ transferData.stgmedium = new STGMEDIUM();
+ transferData.result = COM.E_FAIL;
+
+ final Object data;
+ if (isActive()) {
+ DNDEvent event = new DNDEvent();
+ event.widget = DragSource.this;
+ event.time = OS.GetMessageTime();
+ event.dataType = transferData;
+ notifyListeners(DND.DragSetData,event);
+
+ if (!event.doit) return COM.E_FAIL;
+
+ lastData = event.data;
+ data = event.data;
+ } else {
+ if (lastData == null) {
+ return COM.E_FAIL;
+ }
+ data = lastData;
+ }
+
+ // get matching transfer agent to perform conversion
+ Transfer transfer = null;
+ for (Transfer transferAgent : transferAgents) {
+ if (transferAgent != null && transferAgent.isSupportedType(transferData)){
+ transfer = transferAgent;
+ break;
+ }
+ }
+
+ if (transfer == null) return COM.DV_E_FORMATETC;
+ transfer.javaToNative(data, transferData);
+ if (transferData.result != COM.S_OK) return transferData.result;
+ COM.MoveMemory(pmedium, transferData.stgmedium, STGMEDIUM.sizeof);
+ return transferData.result;
+ }
+
+ private int SetData(long pFormatetc, long pmedium, int fRelease) {
+ if (pFormatetc == 0 || pmedium == 0) return COM.E_INVALIDARG;
+ FORMATETC formatetc = new FORMATETC();
+ COM.MoveMemory(formatetc, pFormatetc, FORMATETC.sizeof);
+ if (formatetc.cfFormat == CFSTR_PERFORMEDDROPEFFECT && formatetc.tymed == COM.TYMED_HGLOBAL) {
+ STGMEDIUM stgmedium = new STGMEDIUM();
+ COM.MoveMemory(stgmedium, pmedium,STGMEDIUM.sizeof);
+ //TODO - this should be GlobalLock()
+ long[] ptrEffect = new long[1];
+ OS.MoveMemory(ptrEffect, stgmedium.unionField, C.PTR_SIZEOF);
+ int[] effect = new int[1];
+ OS.MoveMemory(effect, ptrEffect[0], 4);
+ if (isActive()) {
+ dataEffect = osToOp(effect[0]);
+ }
+ }
+ if (fRelease == 1) {
+ COM.ReleaseStgMedium(pmedium);
+ }
+ return COM.S_OK;
+ }
+ }
+
/**
* Creates a new <code>DragSource</code> to handle dragging from the specified <code>Control</code>.
* Creating an instance of a DragSource may cause system resources to be allocated depending on the platform.
@@ -233,49 +440,10 @@
addListener(DND.DragEnd, typedListener);
}
-private int AddRef() {
- refCount++;
- return refCount;
-}
-
private void createCOMInterfaces() {
- disposeCOMInterfaces();
- // register each of the interfaces that this object implements
- iDropSource = new COMObject(new int[]{2, 0, 0, 2, 1}){
- @Override
- public long method0(long[] args) {return QueryInterface(args[0], args[1]);}
- @Override
- public long method1(long[] args) {return AddRef();}
- @Override
- public long method2(long[] args) {return Release();}
- @Override
- public long method3(long[] args) {return QueryContinueDrag((int)args[0], (int)args[1]);}
- @Override
- public long method4(long[] args) {return GiveFeedback((int)args[0]);}
- };
-
- iDataObject = new COMObject(new int[]{2, 0, 0, 2, 2, 1, 2, 3, 2, 4, 1, 1}){
- @Override
- public long method0(long[] args) {return QueryInterface(args[0], args[1]);}
- @Override
- public long method1(long[] args) {return AddRef();}
- @Override
- public long method2(long[] args) {return Release();}
- @Override
- public long method3(long[] args) {return GetData(args[0], args[1]);}
- // method4 GetDataHere - not implemented
- @Override
- public long method5(long[] args) {return QueryGetData(args[0]);}
- // method6 GetCanonicalFormatEtc - not implemented
- @Override
- public long method7(long[] args) {return SetData(args[0], args[1], (int)args[2]);}
- @Override
- public long method8(long[] args) {return EnumFormatEtc((int)args[0], args[1]);}
- // method9 DAdvise - not implemented
- // method10 DUnadvise - not implemented
- // method11 EnumDAdvise - not implemented
- };
- refCount = 1;
+ releaseCOMInterfaces();
+ iDropSource = new COMIDropSource();
+ iDataObject = new COMIDataObject(transferAgents);
}
@Override
@@ -287,13 +455,13 @@
}
}
-private void disposeCOMInterfaces() {
+private void releaseCOMInterfaces() {
if (iDropSource != null)
- iDropSource.dispose();
+ iDropSource.Release();
iDropSource = null;
if (iDataObject != null)
- iDataObject.dispose();
+ iDataObject.Release();
iDataObject = null;
}
@@ -307,7 +475,6 @@
notifyListeners(DND.DragStart,event);
if (!event.doit || transferAgents == null || transferAgents.length == 0 ) return;
- createCOMInterfaces();
int[] pdwEffect = new int[1];
int operations = opToOs(getStyle());
Display display = control.getDisplay();
@@ -369,6 +536,7 @@
String externalLoopKey = "org.eclipse.swt.internal.win32.externalEventLoop";
int result = COM.DRAGDROP_S_CANCEL;
try {
+ createCOMInterfaces();
display.setData(externalLoopKey, Boolean.TRUE);
result = COM.DoDragDrop(iDataObject.getAddress(), iDropSource.getAddress(), operations, pdwEffect);
} finally {
@@ -383,7 +551,7 @@
topControl = null;
}
display.setData(key, oldValue);
- Release();
+ releaseCOMInterfaces();
}
int operation = osToOp(pdwEffect[0]);
if (dataEffect == DND.DROP_MOVE) {
@@ -394,33 +562,6 @@
}
}
- /*
- * Bug 549643: a proper drag&drop operation is finished when the DoDragDrop loop/function returns.
- * Unfortunately the Windows Explorer is ignoring this fact while showing a Portable Device
- * (e.g. Smartphone attached through MTP). I.e. dropping a file on Windows Explorer in this
- * situation will query the iDataObject at least once for its data _after_ DoDragDrop finished.
- * Revoking this getData request will fail the drop.
- *
- * This behavior can succeeds because most applications store the actual data to transfer in
- * the IDataObject and since its lifetime is managed through ref counting it can return the data
- * even after the drag&drop finished. In SWT the data to transfer is not stored in the IDataObject
- * but instead obtained on demand through a DND.DragSetData event. Additional some clients release
- * the data to drag in the DragEnd event and therefore do not like to get such events after DragEnd.
- *
- * That's why the next few lines exist. In case the DropTarget has not yet released the IDataObject
- * (which is the case for the faulty Windows Explorer described above) we delay the DragEnd event in
- * case an additional DragSetData is triggered. Since the DropTarget can be any (faulty or malicious)
- * application maybe never releasing the object wait is combined with a tight timeout.
- */
- final long start = System.currentTimeMillis();
- while (refCount > 0 && System.currentTimeMillis() - start < 1000) {
- if (!display.readAndDispatch()) {
- try { Thread.sleep(10); }
- catch (InterruptedException e) { break; }
- }
- }
- disposeCOMInterfaces();
-
event = new DNDEvent();
event.widget = this;
event.time = OS.GetMessageTime();
@@ -434,7 +575,7 @@
* Ownership of ppenumFormatetc transfers from callee to caller so reference count on ppenumFormatetc
* must be incremented before returning. Caller is responsible for releasing ppenumFormatetc.
*/
-private int EnumFormatEtc(int dwDirection, long ppenumFormatetc) {
+private static int EnumFormatEtc(Transfer[] transferAgents, int dwDirection, long ppenumFormatetc) {
// only allow getting of data - SetData is not currently supported
if (dwDirection == COM.DATADIR_SET) return COM.E_NOTIMPL;
@@ -472,47 +613,6 @@
return control;
}
-private int GetData(long pFormatetc, long pmedium) {
- /* Called by a data consumer to obtain data from a source data object.
- The GetData method renders the data described in the specified FORMATETC
- structure and transfers it through the specified STGMEDIUM structure.
- The caller then assumes responsibility for releasing the STGMEDIUM structure.
- */
- if (pFormatetc == 0 || pmedium == 0) return COM.E_INVALIDARG;
-
- if (QueryGetData(pFormatetc) != COM.S_OK) return COM.DV_E_FORMATETC;
-
- TransferData transferData = new TransferData();
- transferData.formatetc = new FORMATETC();
- COM.MoveMemory(transferData.formatetc, pFormatetc, FORMATETC.sizeof);
- transferData.type = transferData.formatetc.cfFormat;
- transferData.stgmedium = new STGMEDIUM();
- transferData.result = COM.E_FAIL;
-
- DNDEvent event = new DNDEvent();
- event.widget = this;
- event.time = OS.GetMessageTime();
- event.dataType = transferData;
- notifyListeners(DND.DragSetData,event);
-
- if (!event.doit) return COM.E_FAIL;
-
- // get matching transfer agent to perform conversion
- Transfer transfer = null;
- for (Transfer transferAgent : transferAgents) {
- if (transferAgent != null && transferAgent.isSupportedType(transferData)){
- transfer = transferAgent;
- break;
- }
- }
-
- if (transfer == null) return COM.DV_E_FORMATETC;
- transfer.javaToNative(event.data, transferData);
- if (transferData.result != COM.S_OK) return transferData.result;
- COM.MoveMemory(pmedium, transferData.stgmedium, STGMEDIUM.sizeof);
- return transferData.result;
-}
-
/**
* Returns an array of listeners who will be notified when a drag and drop
* operation is in progress, by sending it one of the messages defined in
@@ -607,7 +707,7 @@
private void onDispose() {
if (control == null) return;
- this.Release();
+ releaseCOMInterfaces();
if (controlListener != null){
control.removeListener(SWT.Dispose, controlListener);
control.removeListener(SWT.DragDetect, controlListener);
@@ -646,7 +746,7 @@
return operation;
}
-private int QueryGetData(long pFormatetc) {
+private static int QueryGetData(Transfer[] transferAgents, long pFormatetc) {
if (transferAgents == null) return COM.E_FAIL;
TransferData transferData = new TransferData();
transferData.formatetc = new FORMATETC();
@@ -666,21 +766,17 @@
* Ownership of ppvObject transfers from callee to caller so reference count on ppvObject
* must be incremented before returning. Caller is responsible for releasing ppvObject.
*/
-private int QueryInterface(long riid, long ppvObject) {
+private static int QueryInterface(COMObject comObject, long riid, long ppvObject) {
if (riid == 0 || ppvObject == 0)
return COM.E_INVALIDARG;
GUID guid = new GUID();
COM.MoveMemory(guid, riid, GUID.sizeof);
- if (COM.IsEqualGUID(guid, COM.IIDIUnknown) || COM.IsEqualGUID(guid, COM.IIDIDropSource)) {
- OS.MoveMemory(ppvObject, new long[] {iDropSource.getAddress()}, C.PTR_SIZEOF);
- AddRef();
- return COM.S_OK;
- }
-
- if (COM.IsEqualGUID(guid, COM.IIDIDataObject) ) {
- OS.MoveMemory(ppvObject, new long[] {iDataObject.getAddress()}, C.PTR_SIZEOF);
- AddRef();
+ if (comObject != null && COM.IsEqualGUID(guid, COM.IIDIUnknown)
+ || (COM.IsEqualGUID(guid, COM.IIDIDropSource) && (comObject instanceof COMIDropSource))
+ || (COM.IsEqualGUID(guid, COM.IIDIDataObject) && (comObject instanceof COMIDataObject))) {
+ OS.MoveMemory(ppvObject, new long[] {comObject.getAddress()}, C.PTR_SIZEOF);
+ comObject.method1(null); // AddRef
return COM.S_OK;
}
@@ -688,17 +784,6 @@
return COM.E_NOINTERFACE;
}
-private int Release() {
- refCount--;
- if (refCount == 0) {
- disposeCOMInterfaces();
- if (COM.FreeUnusedLibraries) {
- COM.CoFreeUnusedLibraries();
- }
- }
- return refCount;
-}
-
/**
* Removes the listener from the collection of listeners who will
* be notified when a drag and drop operation is in progress.
@@ -724,26 +809,6 @@
removeListener(DND.DragEnd, listener);
}
-private int SetData(long pFormatetc, long pmedium, int fRelease) {
- if (pFormatetc == 0 || pmedium == 0) return COM.E_INVALIDARG;
- FORMATETC formatetc = new FORMATETC();
- COM.MoveMemory(formatetc, pFormatetc, FORMATETC.sizeof);
- if (formatetc.cfFormat == CFSTR_PERFORMEDDROPEFFECT && formatetc.tymed == COM.TYMED_HGLOBAL) {
- STGMEDIUM stgmedium = new STGMEDIUM();
- COM.MoveMemory(stgmedium, pmedium,STGMEDIUM.sizeof);
- //TODO - this should be GlobalLock()
- long[] ptrEffect = new long[1];
- OS.MoveMemory(ptrEffect, stgmedium.unionField, C.PTR_SIZEOF);
- int[] effect = new int[1];
- OS.MoveMemory(effect, ptrEffect[0], 4);
- dataEffect = osToOp(effect[0]);
- }
- if (fRelease == 1) {
- COM.ReleaseStgMedium(pmedium);
- }
- return COM.S_OK;
-}
-
/**
* Specifies the drag effect for this DragSource. This drag effect will be
* used during a drag and drop operation.
diff --git a/tests/org.eclipse.swt.tests.win32/ManualTests/org/eclipse/swt/tests/win32/snippets/Bug567422_DNDCrash.java b/tests/org.eclipse.swt.tests.win32/ManualTests/org/eclipse/swt/tests/win32/snippets/Bug567422_DNDCrash.java
new file mode 100644
index 0000000..137c8ab
--- /dev/null
+++ b/tests/org.eclipse.swt.tests.win32/ManualTests/org/eclipse/swt/tests/win32/snippets/Bug567422_DNDCrash.java
@@ -0,0 +1,233 @@
+/*******************************************************************************
+ * Copyright (c) 2020 Paul Pazderski and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ * Paul Pazderski - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.swt.tests.win32.snippets;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.dnd.DND;
+import org.eclipse.swt.dnd.DragSource;
+import org.eclipse.swt.dnd.DropTarget;
+import org.eclipse.swt.dnd.DropTargetEvent;
+import org.eclipse.swt.dnd.DropTargetListener;
+import org.eclipse.swt.dnd.TextTransfer;
+import org.eclipse.swt.dnd.Transfer;
+import org.eclipse.swt.graphics.Point;
+import org.eclipse.swt.internal.ole.win32.IDataObject;
+import org.eclipse.swt.layout.RowLayout;
+import org.eclipse.swt.tests.win32.SwtWin32TestUtil;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Event;
+import org.eclipse.swt.widgets.Shell;
+import org.junit.FixMethodOrder;
+import org.junit.Test;
+import org.junit.runners.MethodSorters;
+
+/**
+ * This one is primary a manual test because it is platform dependent, kind of
+ * slow, a bit unreliable (can succeed even if bug exist; see dragDropCount) and
+ * grabs the mouse while testing. Apart from that the test runs automatically.
+ * Just start and see if the JVM crashes.
+ */
+@FixMethodOrder(MethodSorters.NAME_ASCENDING)
+public class Bug567422_DNDCrash {
+
+ enum TestMode {
+ EXPECTED,
+ UNCOMMON,
+ EVIL,
+ }
+
+ public static void main(String[] args) throws InterruptedException {
+ for (TestMode mode : TestMode.values()) {
+ new Bug567422_DNDCrash().testBug567422(mode);
+ }
+ }
+
+ /**
+ * Simulate drag and drop on a target with expected behaviour which is that the
+ * target release all references on the COM objects it acquires but not more and
+ * therefore is actually finished once the drop is performed.
+ */
+ @Test
+ public void testBug567422_1_expectedDropTarget() throws InterruptedException {
+ testBug567422(TestMode.EXPECTED);
+ }
+
+ /**
+ * Simulate drag and drop on a target with uncommon behaviour which is that the
+ * target does not release all references on the COM objects once the drop is
+ * performed. Holding a reference to the IDataObject after the drop is done or
+ * canceled is not wrong but uncommon.
+ */
+ @Test
+ public void testBug567422_2_uncommonDropTarget() throws InterruptedException {
+ testBug567422(TestMode.UNCOMMON);
+ }
+
+ /**
+ * Simulate drag and drop on a target with evil or faulty behaviour which is that the
+ * target releases more references on the COM objects as it has acquired previously.
+ */
+ @Test
+ public void testBug567422_3_evilDropTarget() throws InterruptedException {
+ testBug567422(TestMode.EVIL);
+ }
+
+ public void testBug567422(TestMode mode) throws InterruptedException {
+ // More DND operations increase the test time but also the chance to trigger a
+ // crash.
+ int dragDropCount = 5;
+ // Decrease to potential speed up test or increase for a little higher chance to
+ // trigger crash if bug exist.
+ // Must be at least 2. This number of DND operations are performed before there
+ // is a chance to find a crash.
+ int testBatchSize = 5;
+ String data = "Test data";
+
+ Shell shell = new Shell();
+ shell.setLayout(new RowLayout());
+ shell.setSize(300, 300);
+ shell.open();
+ try {
+ try {
+ SwtWin32TestUtil.processEvents(shell.getDisplay(), 1000, shell::isVisible);
+ } catch (InterruptedException e) {
+ fail("Initialization interrupted");
+ }
+ assertTrue("Shell not visible.", shell.isVisible());
+
+ Transfer transfer = TextTransfer.getInstance();
+ AtomicBoolean dropped = new AtomicBoolean(false);
+ AtomicReference<String> droppedData = new AtomicReference<>(null);
+ List<IDataObject> dataObjects = new ArrayList<>();
+
+ DragSource source = new DragSource(shell, DND.DROP_LINK | DND.DROP_COPY | DND.DROP_MOVE);
+ source.setTransfer(transfer);
+ source.addListener(DND.DragSetData, event -> event.data = data);
+
+ DropTarget target = new DropTarget(shell, DND.DROP_DEFAULT | DND.DROP_COPY | DND.DROP_LINK | DND.DROP_MOVE);
+ target.setTransfer(transfer);
+ target.addDropListener(new DropTargetListener() {
+ @Override
+ public void drop(DropTargetEvent event) {
+ try {
+ String o = (String) event.data;
+ droppedData.set(o);
+ } catch (ClassCastException ex) {
+ }
+ dropped.set(true);
+
+ if (mode == TestMode.UNCOMMON) {
+ // keep reference on data object and release it eventually later
+ IDataObject dataObject = new IDataObject(event.currentDataType.pIDataObject);
+ dataObject.AddRef();
+ dataObjects.add(dataObject);
+ }
+ if (mode == TestMode.EVIL) {
+ // release more references on data object as acquired
+ IDataObject dataObject = new IDataObject(event.currentDataType.pIDataObject);
+ for (int i = 0; i < 3; i++) {
+ dataObject.Release();
+ }
+ }
+ }
+
+ @Override
+ public void dropAccept(DropTargetEvent event) {
+ }
+
+ @Override
+ public void dragOver(DropTargetEvent event) {
+ }
+
+ @Override
+ public void dragOperationChanged(DropTargetEvent event) {
+ }
+
+ @Override
+ public void dragLeave(DropTargetEvent event) {
+ }
+
+ @Override
+ public void dragEnter(DropTargetEvent event) {
+ }
+ });
+
+ for (int i = 0; i < dragDropCount; i++) {
+ dropped.set(false);
+ droppedData.set(null);
+ int dragDropTries = 3;
+ do {
+ shell.setText(i + "/" + dragDropCount);
+ postDragAndDropEvents(shell);
+ SwtWin32TestUtil.processEvents(shell.getDisplay(), 1000, dropped::get);
+ } while (!dropped.get() && --dragDropTries > 0);
+ assertTrue("No drop received.", dropped.get());
+ assertNotNull("No data was dropped.", droppedData.get());
+
+ if (mode == TestMode.UNCOMMON && (i % testBatchSize) == 0) {
+ for (IDataObject dataObject : dataObjects) {
+ dataObject.Release();
+ }
+ dataObjects.clear();
+ }
+ }
+ if (mode == TestMode.UNCOMMON) {
+ for (IDataObject dataObject : dataObjects) {
+ dataObject.Release();
+ }
+ }
+ } finally {
+ Display display = shell.getDisplay();
+ display.dispose();
+ assertTrue(display.isDisposed());
+ }
+ }
+
+ /**
+ * Posts the events required to do a drag and drop. (i.e. click and hold mouse
+ * button and move mouse)
+ * <p>
+ * The caller is responsible to ensure the generated events are processed by the
+ * event loop.
+ * </p>
+ */
+ private static void postDragAndDropEvents(Shell shell) {
+ shell.forceActive();
+ assertTrue("Test shell requires input focus.", shell.forceFocus());
+ Event event = new Event();
+ Point pt = shell.toDisplay(50, 50);
+ event.x = pt.x;
+ event.y = pt.y;
+ event.type = SWT.MouseMove;
+ shell.getDisplay().post(event);
+ event.button = 1;
+ event.count = 1;
+ event.type = SWT.MouseDown;
+ shell.getDisplay().post(event);
+ event.x += 30;
+ event.type = SWT.MouseMove;
+ shell.getDisplay().post(event);
+ event.type = SWT.MouseUp;
+ shell.getDisplay().post(event);
+ }
+}
