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POUnmanaged callback causing stack to overflow
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copied!<p>I am working with an unmanaged resource with C#. The resource exposes a callback that can be setup for certain events that could happen within the hardware. To gain access to the unmanaged functions I do the following:</p> <pre><code>[DllImportAttribute("testDLL.dll", EntryPoint = "InstallCallback")] public static extern short InstallCallback(uint handle, byte x, byte y, IntFuncPtr ptr); [UnmanagedFunctionPointer(CallingConvention.StdCall)] public delegate void IntFuncPtr(uint handle, byte x, byte y, LogEntry info); </code></pre> <p>I first install the callback with a reference to a method that follows the IntFuncPtr delegate. I then let the hardware go do its thing. After roughly 4700 calls of the callback the application crashes. The callback works fine if I write the code in c/c++ however I can replicate it by removing the __stdcall from my callback function. From C# I cannot catch the error which indicates the application is dying in the unmanaged resource. With the c/c++ application I can see that the stack overflows without __stdcall.</p> <p>I thought that the delegate might not work with the calling convention stdcall so I tried the following:</p> <pre><code>[DllImportAttribute("testDLL.dll", EntryPoint = "InstallCallback")] public static extern short InstallCallback(uint handle, byte x, byte y, IntPtr ptr); public delegate void IntFuncPtr(uint handle, byte x, byte y, LogEntry info); var callBackDelegate = new IntFuncPtr(Callback); var callBackPtr = Marshal.GetFunctionPointerForDelegate(callBackDelegate); InstallCallback(handle, 1, 1, callBackPtr); </code></pre> <p>This also did not work.</p> <p>To summarize, I have an unmanaged callback that requires a function pointer to a function defined as a __stdcall. If the function pointer is to a non __stdcall function then the stack grows and overflows. I am attempting to use the callback in C# using DllImport and an UnmanagedFunctionPointer delegate with stdcall calling convention. When I do this the C# application acts like a c/c++ application that uses a non __stdcall function.</p> <p>How can I get this to work entirely in C#?</p> <p>Edit 1:</p> <p>Here is the native method definition & structure information including the C# structure information.</p> <pre><code>extern "C" __declspec( dllexport ) short __stdcall InstallCallback(unsigned int handle, unsigned char x, unsigned char y, LOG_ENTRY info ); typedef union { unsigned int ul_All; struct { unsigned int ul_Info:24; unsigned int uc_IntType:8; }t; struct { unsigned int ul_Info:24; unsigned int uc_Biu1:1; unsigned int uc_Biu2:1; unsigned int uc_Dma:1; unsigned int uc_Target:1; unsigned int uc_Cmd:1; unsigned int uc_Biu3:1; unsigned int uc_Biu4:1; unsigned int res:1; }b; } LOG_ENTRY_C; typedef union { unsigned int All; struct { AiUInt32 Index:16; AiUInt32 Res:8; AiUInt32 IntSrc:8; }t; } LOG_ENTRY_D; typedef struct log_entry { unsigned int a; unsigned int b; LOG_ENTRY_C c; LOG_ENTRY_D d; } LOG_ENTRY; [StructLayoutAttribute(LayoutKind.Sequential)] public struct LogEntry { public uint Lla; public uint Llb; public LogEntryC Llc; public LogEntryD Lld; } [StructLayoutAttribute(LayoutKind.Explicit)] public struct LogEntryC { [FieldOffsetAttribute(0)] public uint All; [FieldOffsetAttribute(0)] public LogEntryCT t; [FieldOffsetAttribute(0)] public LogEntryCB b; } [StructLayoutAttribute(LayoutKind.Explicit)] public struct LogEntryD { [FieldOffsetAttribute(0)] public uint All; [FieldOffsetAttribute(0)] public LogEntryDT t; } [StructLayoutAttribute(LayoutKind.Sequential)] public struct LogEntryCT { public uint bitvector1; public uint IntType { get { return ((uint)((this.bitvector1 & 255u))); } set { this.bitvector1 = ((uint)((value | this.bitvector1))); } } public uint Info { get { return ((uint)(((this.bitvector1 & 4294967040u) / 256))); } set { this.bitvector1 = ((uint)(((value * 256) | this.bitvector1))); } } } [StructLayoutAttribute(LayoutKind.Sequential)] public struct LogEntryCB { public uint bitvector1; public uint res { get { return ((uint)((this.bitvector1 & 1u))); } set { this.bitvector1 = ((uint)((value | this.bitvector1))); } } public uint Biu4 { get { return ((uint)(((this.bitvector1 & 2u) / 2))); } set { this.bitvector1 = ((uint)(((value * 2) | this.bitvector1))); } } public uint Biu3 { get { return ((uint)(((this.bitvector1 & 4u) / 4))); } set { this.bitvector1 = ((uint)(((value * 4) | this.bitvector1))); } } public uint Cmd { get { return ((uint)(((this.bitvector1 & 8u) / 8))); } set { this.bitvector1 = ((uint)(((value * 8) | this.bitvector1))); } } public uint Target { get { return ((uint)(((this.bitvector1 & 16u) / 16))); } set { this.bitvector1 = ((uint)(((value * 16) | this.bitvector1))); } } public uint Dma { get { return ((uint)(((this.bitvector1 & 32u) / 32))); } set { this.bitvector1 = ((uint)(((value * 32) | this.bitvector1))); } } public uint Biu2 { get { return ((uint)(((this.bitvector1 & 64u) / 64))); } set { this.bitvector1 = ((uint)(((value * 64) | this.bitvector1))); } } public uint Biu1 { get { return ((uint)(((this.bitvector1 & 128u) / 128))); } set { this.bitvector1 = ((uint)(((value * 128) | this.bitvector1))); } } public uint Info { get { return ((uint)(((this.bitvector1 & 4294967040u) / 256))); } set { this.bitvector1 = ((uint)(((value * 256) | this.bitvector1))); } } } [StructLayoutAttribute(LayoutKind.Sequential)] public struct LogEntryDT { public uint bitvector1; public uint IntSrc { get { return ((uint)((this.bitvector1 & 255u))); } set { this.bitvector1 = ((uint)((value | this.bitvector1))); } } public uint Res { get { return ((uint)(((this.bitvector1 & 65280u) / 256))); } set { this.bitvector1 = ((uint)(((value * 256) | this.bitvector1))); } } public uint Index { get { return ((uint)(((this.bitvector1 & 4294901760u) / 65536))); } set { this.bitvector1 = ((uint)(((value * 65536) | this.bitvector1))); } } } </code></pre>

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