Question

我正在使用3. party SDK，它由.dll，.lib和.h文件组成。我正在使用.dll来对付PInvoke。和.h文件一起查看函数名称和参数。（所以我没有使用.lib文件）。

SDK相当复杂，因此制作PInvoke包装器已被证明是一项挑战。所有函数/结构/枚举都在.h文件中定义。

我正在解析非托管C代码的结构，并且该结构包含2个委托，非托管C代码调用它们。

我在C＃中创建结构，并且两个委托都在C＃中设置。

当我调用它时，我得到一个'System.AccessViolationException'。

使用

//C#
private CallBackInterface callBack;

public void MyMethod()
{
    callBack = new CallBackInterface ();
    callBack.event1 = new CallBackInterface.event1_delegate(event1_Handler);
    callBack.event2 = new CallBackInterface.event2_delegate(event2_Handler);
    CallBackFunction(ref callBack); //Throws a 'System.AccessViolationException' 

}  

public int event1_Handler(IntPtr Inst, uint type, uint timeMs)
{
    Console.WriteLine("Got a callback on event 1!");
    return 0;
}

public int event2_Handler(IntPtr Inst, out LH_BOOL Continue)
{
    Console.WriteLine("Got a callback on event 2!");
    Continue = LH_BOOL.TRUE;
    return 0;
}

功能：CallBackFunction

//C 
ERROR CallBackFunction(CallBackInterface  * callBack);

//C#
[DllImport("myDll.dll", EntryPoint = "CallBackFunction", CallingConvention = CallingConvention.Cdecl)]
public static extern ERROR CallBackFunction(ref CallBackInterface callBack);

结构：CallBackInterface

//C 
typedef unsigned long LH_TIME;
typedef struct CallBackInterface_S{
    int (*event1) (void* inst, unsigned long type, LH_TIME timeMs);
    int (*event2) (void* inst, LH_BOOL* Continue); //continue should be set to tell the unmanaged c code if it should continue or stop.
} CallBackInterface;

//C#
[StructLayout(LayoutKind.Sequential)]
public struct CallBackInterface
{
    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    public delegate int event1_delegate(IntPtr inst, uint type, uint timeMs);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    public delegate int event2_delegate(IntPtr inst, out LH_BOOL Continue);

    public event1_delegate event1;
    public event2_delegate event2;
}

枚举：LH_BOOL

//C Enum: LH_BOOL
typedef enum LH_BOOL_E {
    FALSE= 0, 
    TRUE = 1, 
 } LH_BOOL;

 //C# Enum: LH_BOOL
 public enum LH_BOOL
 {
   FALSE= 0, 
   TRUE = 1, 
 }

枚举：错误

//C Enum: ERROR 
typedef enum ERROR_E {
    OK = 0, //Everything is ok
    E_ARG = 1, //Error in the Arguments 
    E_DATA = 2 //Data error
    //And more...
 } ERROR;

 //C# Enum: ERROR
 public enum ERROR
 {
    OK = 0, //Everything is ok
    E_ARG = 1, //Error in the Arguments 
    E_DATA = 2 //Data error
    //And more...
 }

Answer 1

回调可能是cdecl，但我对此更加怀疑：

[DllImport("myDll.dll", EntryPoint = "CallBackFunction", CallingConvention = CallingConvention.Cdecl)]
public static extern ERROR CallBackFunction(ref CallBackInterface callBack);

你有没有这样尝试过（如果你没有尝试在C ++中使用与C＃不同的名称，那么EntryPoint是多余的，而stdcall是DllImport的默认调用约定，通常用于DLL导出）： / p>

[DllImport("myDll.dll")]
public static extern ERROR CallBackFunction(ref CallBackInterface callBack);

Answer 2

anwser是，我的CallBackInterface出了问题，我有：

public delegate int event2_delegate(IntPtr inst, out LH_BOOL Continue);

这应该是

public delegate int event2_delegate(IntPtr inst, ref LH_BOOL Continue);

原因是3. party在内存中分配LH_BOOL Continue，然后我必须为其设置正确的值。但是使用＆＃34; out＆＃34;表示C＃将分配该值，当3.方尝试设置它时，它会尝试设置一个它无权访问的值。＆＃34; REF＆＃34;通过允许将现有值作为参数传递来解决此问题。

所以最终的代码如下：

使用

//C# private CallBackInterface callBack; public void MyMethod() { callBack = new CallBackInterface (); callBack.event1 = new CallBackInterface.event1_delegate(event1_Handler); callBack.event2 = new CallBackInterface.event2_delegate(event2_Handler); CallBackFunction(ref callBack); } public int event1_Handler(IntPtr Inst, uint type, uint timeMs) { Console.WriteLine("Got a callback on event 1!"); return 0; } public int event2_Handler(IntPtr Inst, out LH_BOOL Continue) { Console.WriteLine("Got a callback on event 2!"); Continue = LH_BOOL.TRUE; return 0; }

功能：CallBackFunction

//C ERROR CallBackFunction(CallBackInterface * callBack); //C# [DllImport("myDll.dll", EntryPoint = "CallBackFunction", CallingConvention = CallingConvention.Cdecl)] public static extern ERROR CallBackFunction(ref CallBackInterface callBack);

结构：CallBackInterface

//C typedef unsigned long LH_TIME; typedef struct CallBackInterface_S{ int (*event1) (void* inst, unsigned long type, LH_TIME timeMs); int (*event2) (void* inst, LH_BOOL* Continue); //continue should be set to tell the unmanaged c code if it should continue or stop. } CallBackInterface; //C# [StructLayout(LayoutKind.Sequential)] public struct CallBackInterface { [UnmanagedFunctionPointer(CallingConvention.Cdecl)] public delegate int event1_delegate(IntPtr inst, uint type, uint timeMs); [UnmanagedFunctionPointer(CallingConvention.Cdecl)] public delegate int event2_delegate(IntPtr inst, ref LH_BOOL Continue); public event1_delegate event1; public event2_delegate event2; }

枚举：LH_BOOL

//C Enum: LH_BOOL typedef enum LH_BOOL_E { FALSE= 0, TRUE = 1, } LH_BOOL; //C# Enum: LH_BOOL public enum LH_BOOL { FALSE= 0, TRUE = 1, }

枚举：错误

//C Enum: ERROR typedef enum ERROR_E { OK = 0, //Everything is ok E_ARG = 1, //Error in the Arguments E_DATA = 2 //Data error //And more... } ERROR; //C# Enum: ERROR public enum ERROR { OK = 0, //Everything is ok E_ARG = 1, //Error in the Arguments E_DATA = 2 //Data error //And more... }

在使用PInvoke时，我很高兴使用IntPtr作为函数的输入和输出。好处是C＃不会做出任何限制，挑战是要使其正确并且需要额外的工作。为了能够使它正确，它需要您调用的函数有详细记录，因此您确切地知道输入和输出在内存中应该是什么样子。

C＃如何在结构中进行Pinvoke回调

2 个答案: