From: Eberhard Beilharz <eb1@sil.org>
Date: Thu, 13 Mar 2014 17:55:39 +0000 (+0100)
Subject: Set ErrorInfo in Marshal.GetHRForException
X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=commitdiff_plain;h=2d420bfb7a394884b7f8f52368907db186b855d9;p=mono.git

Set ErrorInfo in Marshal.GetHRForException

Marshal.GetHRForException had a MonoTODO because it needs to set
the errorinfo object so that exceptions get properly passed to
unmanaged code. Since not all managed exceptions have a corresponding
HR value but we might need to get to the original thrown exception
we implement a ManagedErrorInfo helper class that implements the
IErrorInfo interface but also stores the exception.

In GetExceptionForHR we check if the errorinfo we get is a
ManagedErrorInfo. If it is we return the exception stored in there
(if it converts to the same error code), otherwise we construct a new
exception.
---

diff --git a/mcs/class/corlib/System.Runtime.InteropServices/ManagedErrorInfo.cs b/mcs/class/corlib/System.Runtime.InteropServices/ManagedErrorInfo.cs
new file mode 100644
index 00000000000..c77857c9db4
--- /dev/null
+++ b/mcs/class/corlib/System.Runtime.InteropServices/ManagedErrorInfo.cs
@@ -0,0 +1,63 @@
+// ManagedErrorInfo class
+//
+// Eberhard Beilharz (eb1@sil.org)
+//
+// Copyright (C) 2012 SIL International
+using System;
+using System.Runtime.CompilerServices;
+using System.Security;
+
+namespace System.Runtime.InteropServices
+{
+	/// <summary>
+	/// Helper class that allows to pass an exception as an IErrorInfo object. This is useful
+	/// when we get an exception in managed code that is called from unmanaged code that is called
+	/// from managed code and we want to get to the exception in the outer managed code.
+	/// </summary>
+	internal class ManagedErrorInfo: IErrorInfo
+	{
+		private Exception m_Exception;
+		public ManagedErrorInfo (Exception e)
+		{
+			m_Exception = e;
+		}
+
+		public Exception Exception {
+			get { return m_Exception; }
+		}
+
+		#region IErrorInfo
+		public int GetGUID (out Guid guid)
+		{
+			// not supported
+			guid = Guid.Empty;
+			return 0;
+		}
+
+		public int GetSource (out string source)
+		{
+			source = m_Exception.Source;
+			return 0;
+		}
+
+		public int GetDescription (out string description)
+		{
+			description = m_Exception.Message;
+			return 0;
+		}
+
+		public int GetHelpFile (out string helpFile)
+		{
+			helpFile = m_Exception.HelpLink;
+			return 0;
+		}
+
+		public int GetHelpContext(out uint helpContext)
+		{
+			// not supported
+			helpContext = 0;
+			return 0;
+		}
+		#endregion
+	}
+}
diff --git a/mcs/class/corlib/System.Runtime.InteropServices/Marshal.cs b/mcs/class/corlib/System.Runtime.InteropServices/Marshal.cs
index bddd71f12b5..95df86a7c8f 100644
--- a/mcs/class/corlib/System.Runtime.InteropServices/Marshal.cs
+++ b/mcs/class/corlib/System.Runtime.InteropServices/Marshal.cs
@@ -414,9 +414,11 @@ namespace System.Runtime.InteropServices
 #endif // !FULL_AOT_RUNTIME
 
 #if !FULL_AOT_RUNTIME
-		[MonoTODO ("SetErrorInfo")]
 		public static int GetHRForException (Exception e)
 		{
+			var errorInfo = new ManagedErrorInfo(e);
+			SetErrorInfo (0, errorInfo);
+
 			return e.hresult;
 		}
 
@@ -1520,12 +1522,36 @@ namespace System.Runtime.InteropServices
 			return null;
 		}
 
+		[DllImport ("oleaut32.dll", CharSet=CharSet.Unicode, EntryPoint = "SetErrorInfo")]
+		static extern int _SetErrorInfo (int dwReserved,
+			[MarshalAs(UnmanagedType.Interface)] IErrorInfo pIErrorInfo);
+
 		[DllImport ("oleaut32.dll", CharSet=CharSet.Unicode, EntryPoint = "GetErrorInfo")]
 		static extern int _GetErrorInfo (int dwReserved,
 			[MarshalAs(UnmanagedType.Interface)] out IErrorInfo ppIErrorInfo);
 
+		static bool SetErrorInfoNotAvailable;
 		static bool GetErrorInfoNotAvailable;
 
+		internal static int SetErrorInfo (int dwReserved, IErrorInfo errorInfo)
+		{
+			int retVal = 0;
+			errorInfo = null;
+
+			if (SetErrorInfoNotAvailable)
+				return -1;
+
+			try {
+				retVal = _SetErrorInfo (dwReserved, errorInfo);
+			}
+			catch (Exception) {
+				// ignore any exception - probably there's no suitable SetErrorInfo
+				// method available.
+				SetErrorInfoNotAvailable = true;
+			}
+			return retVal;
+		}
+
 		internal static int GetErrorInfo (int dwReserved, out IErrorInfo errorInfo)
 		{
 			int retVal = 0;
@@ -1552,10 +1578,8 @@ namespace System.Runtime.InteropServices
 
 		public static Exception GetExceptionForHR (int errorCode, IntPtr errorInfoPtr)
 		{
-			Exception e = ConvertHrToException (errorCode);
-
-			if (errorInfoPtr != (IntPtr)(-1) && e != null) {
-				IErrorInfo errorInfo = null;
+			IErrorInfo errorInfo = null;
+			if (errorInfoPtr != (IntPtr)(-1)) {
 				if (errorInfoPtr == IntPtr.Zero) {
 					if (GetErrorInfo (0, out errorInfo) != 0) {
 						errorInfo = null;
@@ -1563,22 +1587,27 @@ namespace System.Runtime.InteropServices
 				} else {
 					errorInfo = Marshal.GetObjectForIUnknown (errorInfoPtr) as IErrorInfo;
 				}
+			}
 
-				if (errorInfo != null) {
-					uint helpContext;
-					errorInfo.GetHelpContext (out helpContext);
-					string str;
-					errorInfo.GetSource (out str);
-					e.Source = str;
-					errorInfo.GetDescription (out str);
-					e.SetMessage (str);
-					errorInfo.GetHelpFile (out str);
-
-					if (helpContext == 0) {
-						e.HelpLink = str;
-					} else {
-						e.HelpLink = string.Format ("{0}#{1}", str, helpContext);
-					}
+			if (errorInfo is ManagedErrorInfo && ((ManagedErrorInfo)errorInfo).Exception.hresult == errorCode) {
+				return ((ManagedErrorInfo)errorInfo).Exception;
+			}
+
+			Exception e = ConvertHrToException (errorCode);
+			if (errorInfo != null && e != null) {
+				uint helpContext;
+				errorInfo.GetHelpContext (out helpContext);
+				string str;
+				errorInfo.GetSource (out str);
+				e.Source = str;
+				errorInfo.GetDescription (out str);
+				e.SetMessage (str);
+				errorInfo.GetHelpFile (out str);
+
+				if (helpContext == 0) {
+					e.HelpLink = str;
+				} else {
+					e.HelpLink = string.Format ("{0}#{1}", str, helpContext);
 				}
 			}
 			return e;
diff --git a/mcs/class/corlib/corlib.dll.sources b/mcs/class/corlib/corlib.dll.sources
index 1a874b863d1..0bf28c2287d 100644
--- a/mcs/class/corlib/corlib.dll.sources
+++ b/mcs/class/corlib/corlib.dll.sources
@@ -818,6 +818,7 @@ System.Runtime.InteropServices/InvalidOleVariantTypeException.cs
 System.Runtime.InteropServices/LCIDConversionAttribute.cs
 System.Runtime.InteropServices/LIBFLAGS.cs
 System.Runtime.InteropServices/LayoutKind.cs
+System.Runtime.InteropServices/ManagedErrorInfo.cs
 System.Runtime.InteropServices/Marshal.cs
 System.Runtime.InteropServices/MarshalAsAttribute.cs
 System.Runtime.InteropServices/MarshalDirectiveException.cs