Replaced a NullReferedeException that was lost in the interop layer w… (

#12528) Replaced a NullReferenceException that was lost in the interop layer with an HRESULT error code recommended in the docs - https://learn.microsoft.com/en-us/windows/win32/api/objidl/nf-objidl-idataobject-getdatahere#return-value. The HRESULT is not bubbled up through OleFlushClipboard either, this API returns S_OK even when the data wasn't set. In this case we end up with format being set successfully, but data is actually missing.
dotnet · Nov 22, 2024 · 441fb2a · 441fb2a
1 parent 200451f
commit 441fb2a
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Showing 3 changed files with 23 additions and 14 deletions.
diff --git a/src/System.Windows.Forms.Design/src/System/Windows/Forms/Design/ButtonBaseDesigner.cs b/src/System.Windows.Forms.Design/src/System/Windows/Forms/Design/ButtonBaseDesigner.cs
@@ -15,8 +15,6 @@ namespace System.Windows.Forms.Design;
 /// </summary>
 internal class ButtonBaseDesigner : ControlDesigner
 {
-    // private DesignerActionListCollection _actionlists;
-
     public ButtonBaseDesigner()
     {
         AutoResizeHandles = true;
@@ -31,7 +29,6 @@ public override void InitializeNewComponent(IDictionary? defaultValues)
         {
             // Dev10 Bug 685319: We should set the UseVisualStyleBackColor to trun only
             // when this property has not been set/changed by user
-            //
             if (!prop.ShouldSerializeValue(Component))
             {
                 prop.SetValue(Component, true);

diff --git a/...dows.Forms/src/System/Windows/Forms/OLE/DataObject.Composition.WinFormsToNativeAdapter.cs b/...dows.Forms/src/System/Windows/Forms/OLE/DataObject.Composition.WinFormsToNativeAdapter.cs
@@ -116,13 +116,16 @@ HRESULT Com.IDataObject.Interface.GetDataHere(FORMATETC* pformatetc, STGMEDIUM*
                     return HRESULT.DV_E_FORMATETC;
                 }
 
-                object? data = _dataObject.GetData(format);
+                if (_dataObject.GetData(format) is not object data)
+                {
+                    return HRESULT.E_UNEXPECTED;
+                }
 
                 if (((TYMED)pformatetc->tymed).HasFlag(TYMED.TYMED_HGLOBAL))
                 {
                     try
                     {
-                        return SaveDataToHGLOBAL(data!, format, ref *pmedium);
+                        return SaveDataToHGLOBAL(data, format, ref *pmedium);
                     }
                     catch (NotSupportedException ex)
                     {
@@ -314,7 +317,7 @@ DataFormats.DibConstant when data is Image
                 _ when format == DataFormats.SerializableConstant || data is ISerializable || data.GetType().IsSerializable
 #pragma warning restore
                     => SaveObjectToHGLOBAL(ref medium.hGlobal, data, RestrictDeserializationToSafeTypes(format)),
-                _ => HRESULT.E_FAIL
+                _ => HRESULT.E_UNEXPECTED
             };
 
             private static HRESULT SaveObjectToHGLOBAL(ref HGLOBAL hglobal, object data, bool restrictSerialization)

diff --git a/src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/ClipboardTests.cs b/src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/ClipboardTests.cs
@@ -232,15 +232,26 @@ public void Clipboard_SetData_Invoke_GetReturnsExpected(string format, object? d
     [InlineData(null)]
     public void Clipboard_SetData_EmptyOrWhitespaceFormat_ThrowsArgumentException(string? format)
     {
-        Action action = () => Clipboard.SetData(format!, data: null!);
+        Action action = () => Clipboard.SetData(format!, "data");
         action.Should().Throw<ArgumentException>().WithParameterName("format");
     }
 
     [WinFormsFact]
-    public void Clipboard_SetData_null_Success()
+    public void Clipboard_SetData_null_NotThrow()
     {
-        Action action = () => Clipboard.SetData("MyData", data: null!);
-        action.Should().NotThrow();
+        try
+        {
+            Action action = () => Clipboard.SetData("MyData", data: null!);
+            action.Should().NotThrow();
+            // Clipboard flushes format only, content is not stored.
+            // GetData will hit "Data on clipboard is invalid (0x800401D3 (CLIPBRD_E_BAD_DATA))"
+            Clipboard.ContainsData("MyData").Should().BeTrue();
+            Clipboard.GetData("MyData").Should().BeNull();
+        }
+        finally
+        {
+            Clipboard.Clear();
+        }
     }
 
     [WinFormsTheory]
@@ -264,8 +275,7 @@ public void Clipboard_SetDataObject_InvokeObjectIComDataObject_GetReturnsExpecte
         DataObject dataObject = new(data);
         Clipboard.SetDataObject(dataObject);
 
-        var actual = Clipboard.GetDataObject();
-        Assert.NotNull(actual);
+        DataObject actual = Clipboard.GetDataObject().Should().BeOfType<DataObject>().Subject;
         actual.GetData(data.GetType()).Should().Be(data);
         Clipboard.ContainsData(data.GetType().FullName).Should().BeTrue();
     }
@@ -279,8 +289,7 @@ public void Clipboard_SetDataObject_InvokeObjectBoolNotIComDataObject_GetReturns
     {
         Clipboard.SetDataObject(data, copy);
 
-        var dataObject = Clipboard.GetDataObject();
-        Assert.NotNull(dataObject);
+        DataObject dataObject = Clipboard.GetDataObject().Should().BeOfType<DataObject>().Subject;
         dataObject.GetData(data.GetType()).Should().Be(data);
         Clipboard.ContainsData(data.GetType().FullName).Should().BeTrue();
     }