Bringing DCOM remoting functionality to Windows CE and .NET CF2.0

////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2006 Werner Willemsens
//
////////////////////////////////////////////////////////////////////

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace ComError
{
    class ComError
    {
        [System.Runtime.InteropServices.DllImport("oleaut32.dll")]
        private static extern uint GetErrorInfo(uint dwReserved, /* IErrorInfo** */ref IntPtr ppErrorInfo);

        [System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
        public struct ErrorInfo
        {
//          public uint m_cRefs;
            public Guid m_guid;
            public string m_bstrSource;
            public string m_bstrDescription;
            public string m_bstrHelpFile;
            public uint m_dwHelpContext;
        };

        public static System.Runtime.InteropServices.COMException GetRichErrorInfo(System.Runtime.InteropServices.COMException error)
        {
            System.Runtime.InteropServices.COMException error2;
#if WindowsCE
            if ((error.ErrorCode & 0x0000FFFF) > 0x01FF)
            {
                uint HRESULT;
                ErrorInfo err = new ErrorInfo();
                IntPtr ptr = new IntPtr(0);

                HRESULT = GetErrorInfo(0, ref ptr);

                if (HRESULT == 0)
                {
                    // Guid
                    IntPtr pAddressGuid = new IntPtr((int)ptr.ToInt32() + 12);
                    byte[] bGuid = new byte[16];
                    Marshal.Copy(pAddressGuid, bGuid, 0, 16);

                    err.m_guid = new Guid(bGuid);

                    // HelpContext
                    IntPtr pAddressHelpContext = new IntPtr((int)ptr.ToInt32() + 40);
                    int[] iHelpContext = new int[1];
                    Marshal.Copy(pAddressHelpContext, iHelpContext, 0, 1);

                    err.m_dwHelpContext = (uint)iHelpContext[0];

                    // Description
                    IntPtr ppAddressDescription = new IntPtr((int)ptr.ToInt32() + 32);
                    int[] iAddressDescription = new int[1];
                    Marshal.Copy(ppAddressDescription, iAddressDescription, 0, 1);

                    if (iAddressDescription[0] != 0)
                    {
                        IntPtr pAddressDescriptionCount = new IntPtr((int)iAddressDescription[0] - 4);
                        int[] AddressDescriptionCount = new int[1];
                        Marshal.Copy(pAddressDescriptionCount, AddressDescriptionCount, 0, 1);

                        IntPtr pAddressDescription = new IntPtr((int)iAddressDescription[0]);
                        char[] aDescription = new char[AddressDescriptionCount[0]];
                        Marshal.Copy(pAddressDescription, aDescription, 0, AddressDescriptionCount[0] - 1);

                        err.m_bstrDescription = new string(aDescription);
                    }
                    else
                        err.m_bstrDescription = null;

                    // Source
                    IntPtr ppAddressSource = new IntPtr((int)ptr.ToInt32() + 28);
                    int[] iAddressSource = new int[1];
                    Marshal.Copy(ppAddressSource, iAddressSource, 0, 1);

                    if (iAddressSource[0] != 0)
                    {
                        IntPtr pAddressSourceCount = new IntPtr((int)iAddressSource[0] - 4);
                        int[] AddressSourceCount = new int[1];
                        Marshal.Copy(pAddressSourceCount, AddressSourceCount, 0, 1);

                        IntPtr pAddressSource = new IntPtr((int)iAddressSource[0]);
                        char[] aSource = new char[AddressSourceCount[0]];
                        Marshal.Copy(pAddressSource, aSource, 0, AddressSourceCount[0] - 1);

                        err.m_bstrSource = new string(aSource);
                    }
                    else
                        err.m_bstrSource = null;

                    // HelpFile
                    IntPtr ppAddressHelpFile = new IntPtr((int)ptr.ToInt32() + 36);
                    int[] iAddressHelpFile = new int[1];
                    Marshal.Copy(ppAddressHelpFile, iAddressHelpFile, 0, 1);

                    if (iAddressHelpFile[0] != 0)
                    {
                        IntPtr pAddressHelpFileCount = new IntPtr((int)iAddressHelpFile[0] - 4);
                        int[] AddressHelpFileCount = new int[1];
                        Marshal.Copy(pAddressHelpFileCount, AddressHelpFileCount, 0, 1);

                        IntPtr pAddressHelpFile = new IntPtr((int)iAddressHelpFile[0]);
                        char[] aHelpFile = new char[AddressHelpFileCount[0]];
                        Marshal.Copy(pAddressHelpFile, aHelpFile, 0, AddressHelpFileCount[0] - 1);

                        err.m_bstrHelpFile = new string(aHelpFile);
                    }
                    else
                        err.m_bstrHelpFile = null;
                }

                error2 = new System.Runtime.InteropServices.COMException(err.m_bstrDescription, error.ErrorCode);
            }
            else
#endif
            {
                error2 = error;
            }

            return error2;
        }
    }
}