1 files changed, 98 insertions, 0 deletions
diff --git a/src/debug/inc/readonlydatatargetfacade.h b/src/debug/inc/readonlydatatargetfacade.h
new file mode 100644
index 0000000000..5ba4ac39ca
--- /dev/null
+++ b/src/debug/inc/readonlydatatargetfacade.h
@@ -0,0 +1,98 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+//*****************************************************************************
+// ReadOnlyDataTargetFacade.h
+// 
+
+// 
+//*****************************************************************************
+
+#ifndef READONLYDATATARGETFACADE_H_
+#define READONLYDATATARGETFACADE_H_
+
+#include <cordebug.h>
+
+//---------------------------------------------------------------------------------------
+//  ReadOnlyDataTargetFacade
+//  
+//  This class is designed to be used as an ICorDebugMutableDataTarget when none is 
+//  supplied.  All of the write APIs will fail with CORDBG_E_TARGET_READONLY as required
+//  by the data target spec when a write operation is invoked on a read-only data target.
+//  The desire here is to merge the error code paths for the case when a write fails,
+//  and the case when a write is requested but the data target supplied doesn't
+//  implement ICorDebugMutableDataTarget.  
+//  
+//  Note that this is intended to be used only for the additional APIs defined by
+//  ICorDebugMutableDataTarget.  Calling any of the base ICorDebugDataTarget APIs
+//  will ASSERT and fail.  An alternative design would be to make this class a wrapper
+//  class (similar to DataTargetAdapter) over an existing ICorDebugDataTarget interface.
+//  In general, we'd like callers of the data target to differentiate between when they're
+//  using read-only APIs and mutation APIs since they need to be aware that the latter often
+//  won't be supported by the data target.  Also, that design would have the draw-back 
+//  of incuring an extra virtual dispatch on every read API call (makaing debugging more 
+//  complex and possibly having a performance impact).
+// 
+class ReadOnlyDataTargetFacade : public ICorDebugMutableDataTarget
+{
+public:
+    ReadOnlyDataTargetFacade();
+
+    //
+    // IUnknown.
+    //        
+    virtual HRESULT STDMETHODCALLTYPE QueryInterface(
+        REFIID InterfaceId,
+        PVOID* Interface);
+
+    virtual ULONG STDMETHODCALLTYPE AddRef();
+
+    virtual ULONG STDMETHODCALLTYPE Release();
+
+    //
+    // ICorDebugDataTarget.
+    //
+    
+    virtual HRESULT STDMETHODCALLTYPE GetPlatform( 
+        CorDebugPlatform *pPlatform);
+
+    virtual HRESULT STDMETHODCALLTYPE ReadVirtual( 
+        CORDB_ADDRESS address,
+        BYTE * pBuffer,
+        ULONG32 request,
+        ULONG32 * pcbRead);
+
+    virtual HRESULT STDMETHODCALLTYPE GetThreadContext(
+        DWORD dwThreadID,
+        ULONG32 contextFlags,
+        ULONG32 contextSize,
+        BYTE * context);
+
+    //
+    // ICorDebugMutableDataTarget.
+    // 
+
+    virtual HRESULT STDMETHODCALLTYPE WriteVirtual( 
+        CORDB_ADDRESS address,
+        const BYTE * pBuffer,
+        ULONG32 request);
+
+    virtual HRESULT STDMETHODCALLTYPE SetThreadContext(
+        DWORD dwThreadID,
+        ULONG32 contextSize,
+        const BYTE * context);
+
+    virtual HRESULT STDMETHODCALLTYPE ContinueStatusChanged(
+        DWORD dwThreadId,
+        CORDB_CONTINUE_STATUS dwContinueStatus);
+
+private:
+    // Reference count.
+    LONG m_ref;
+};
+
+#include "readonlydatatargetfacade.inl"
+
+#endif //  READONLYDATATARGETFACADE_H_
+