调用非托管回调后程序会爆炸 [英] Program blows up after unmanaged callback is called

问题描述

我有一个需要从我的c＃应用程序调用的c dll。

我让它与dll通信，但是我遇到了回调问题。



c看起来像这样。

I have an c dll that I need to call from my c# application.
I have it communicating with the dll, but I am having issues with callbacks.

The c looks like this.

typedef void (CDECLCALL_CONV *ConnectedCB) (DPHandle hdl);

typedef struct
{
unsigned int size;	// sizeof(DPcbs)
ConnectedCB connectedCB;
.. more callbacks
} DPcbs;

BPS_DP_API unsigned long CDECLCALL_CONV DPSetCallBacks(DPHandle hdl, DPcbs *DPcbs);

我是什么尝试过：



我创建了一个包装非托管代码的接口类。

它看起来像这样

What I have tried:

I have created a interface class that wraps the unmanaged code.
It looks like this

  [System.Runtime.InteropServices.UnmanagedFunctionPointerAttribute(System.Runtime.InteropServices.CallingConvention.Cdecl)]
  public delegate void ConnectedCB(ref DocProcHandle hdl);

  [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
public struct DPcbs
{
  public uint size;
  public ConnectedCB connectedCB;
... more callbacks
}
[System.Runtime.InteropServices.DllImportAttribute("DocProc.dll", EntryPoint = "DPSetCallBacks", CallingConvention = System.Runtime.InteropServices.CallingConvention.Cdecl)]
    public static extern uint DPSetCallBacks(ref DocProcHandle hdl, ref DPcbs DPcbs);

最后我的c＃调用代码

Finally My c# calling code

{
  ...
  // this code is in a static class in the constructor
  // it should not be garbage collected right?
  m_events = new DPcbs();
  m_events.connectedCB = connected;
  m_events.size = Convert.ToUInt32(Marshal.SizeOf<DPcbs>());

  wrapper.DPSetCallBacks(ref m_handle, ref m_events);
  ...
}
private void connected(ref DocProcHandle hdl)
{
  // do something here
}

应用程序停止工作 - 没有错误只是崩溃。

但它发生在调用连接方法之后，在任何事情之前否则。

如果我没有设置连接的回调，它不会崩溃。 （如果它试图调用我的任何回调，它似乎会崩溃）



我已经尝试了所有我能想到的方法以确保该方法不通过GC 。

这个类是静态的，我把方法设为静态。我有Alloc'ed方法和事件。



我有什么遗漏或做错了吗？

有关尝试什么的建议吗？

The application "stopped working" - no error just a crash.
But it happens AFTER the connected method is called, and before anything else.
If I do not set the connected callback it does not crash. (it seems to crash if it tries to call any of my callbacks)

I have tried everything i can think of to make sure the method does not go through the GC.
The class is static, I have made the method static. I have Alloc'ed both the method and the event.

Is there anything I am missing or doing wrong?
Any suggestions on what to try?

推荐答案

您无法以您尝试的方式将委托传递给非托管代码。如果你要将它作为函数指针传递给结构，你应该调用：

You can't pass the delegate to unmanaged code the way you are trying to do. If you are going to pass it as a function pointer inside a structure, you should call:

IntPtr NativeFunctionPointer = Marshal.GetFunctionPointerForDelegate(connected);

然后传递 NativeFunctionPointer 作为函数指针。



原因是托管委托不仅仅包含一个函数地址。它有许多其他.NET类的代码和数据，因此传递其地址与传递其函数入口点不同。

Then pass NativeFunctionPointer as the function pointer.

The reason is that a managed delegate consists of more than just a function address. It has code and data like many other .NET classes, so passing its address isn't the same as passing its function entry point.

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