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POP/Invoke Interop Assistant: Is this actually correct?
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copied!<p>I've got the following structs in C++: (Using pragma pack 1)</p> <pre><code>typedef struct _wfs_cdm_physicalcu { LPSTR lpPhysicalPositionName; CHAR cUnitID[5]; ULONG ulInitialCount; ULONG ulCount; ULONG ulRejectCount; ULONG ulMaximum; USHORT usPStatus; BOOL bHardwareSensor; } WFSCDMPHCU, * LPWFSCDMPHCU; typedef struct _wfs_cdm_cashunit { USHORT usNumber; USHORT usType; LPSTR lpszCashUnitName; CHAR cUnitID[5]; CHAR cCurrencyID[3]; ULONG ulValues; ULONG ulInitialCount; ULONG ulCount; ULONG ulRejectCount; ULONG ulMinimum; ULONG ulMaximum; BOOL bAppLock; USHORT usStatus; USHORT usNumPhysicalCUs; LPWFSCDMPHCU *lppPhysical; } WFSCDMCASHUNIT, * LPWFSCDMCASHUNIT; typedef struct _wfs_cdm_cu_info { USHORT usTellerID; USHORT usCount; LPWFSCDMCASHUNIT *lppList; } WFSCDMCUINFO, * LPWFSCDMCUINFO; </code></pre> <p>P/Invoke Interop Assistant gives me the following output:</p> <pre><code>[System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential, CharSet=System.Runtime.InteropServices.CharSet.Ansi, Pack = 1)] public struct WFSCDMPHCU { /// LPSTR->CHAR* [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPStr)] public string lpPhysicalPositionName; /// CHAR[5] [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=5)] public string cUnitID; /// ULONG->unsigned int public uint ulInitialCount; /// ULONG->unsigned int public uint ulCount; /// ULONG->unsigned int public uint ulRejectCount; /// ULONG->unsigned int public uint ulMaximum; /// USHORT->unsigned short public ushort usPStatus; /// BOOL->int public int bHardwareSensor; } [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential, CharSet=System.Runtime.InteropServices.CharSet.Ansi, Pack = 1)] public struct WFSCDMCASHUNIT { /// USHORT->unsigned short public ushort usNumber; /// USHORT->unsigned short public ushort usType; /// LPSTR->CHAR* [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPStr)] public string lpszCashUnitName; /// CHAR[5] [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=5)] public string cUnitID; /// CHAR[3] [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=3)] public string cCurrencyID; /// ULONG->unsigned int public uint ulValues; /// ULONG->unsigned int public uint ulInitialCount; /// ULONG->unsigned int public uint ulCount; /// ULONG->unsigned int public uint ulRejectCount; /// ULONG->unsigned int public uint ulMinimum; /// ULONG->unsigned int public uint ulMaximum; /// BOOL->int public int bAppLock; /// USHORT->unsigned short public ushort usStatus; /// USHORT->unsigned short public ushort usNumPhysicalCUs; /// LPWFSCDMPHCU* public System.IntPtr lppPhysical; } [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential, Pack = 1)] public struct WFSCDMCUINFO { /// USHORT->unsigned short public ushort usTellerID; /// USHORT->unsigned short public ushort usCount; /// LPWFSCDMCASHUNIT* public System.IntPtr lppList; } </code></pre> <p>However, when using Marshal.PtrToStruct (say, on WFSCDMCUINFO.lppList) I get garbage; when viewing memory using Visual Studio, I see the actual contents in another memory entry (not lppList per se).</p> <p>Are these conversions correct? Is my trust in P/Invoke Interop Assistant misplaced?</p> <p>EDIT:</p> <p>This is the code I use to Marshal to/from IntPtr. I know the Thread idea sucks, but I'll get to that later...</p> <pre><code> public static IntPtr GetIntPtr(this object obj) { try { var handle = GCHandle.Alloc(obj, GCHandleType.Pinned); var thread = new Thread(() => { Thread.Sleep(20000); handle.Free(); }); thread.Start(); return handle.AddrOfPinnedObject(); } catch (ArgumentException) { var ptr = Marshal.AllocHGlobal(Marshal.SizeOf(obj)); Marshal.StructureToPtr(obj, ptr, false); return ptr; } } public static T FromIntPtr<T>(this IntPtr ptr) { if (ptr == IntPtr.Zero) return default(T); return (T) Marshal.PtrToStructure(ptr, typeof (T)); } </code></pre>

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