当尝试调用c#回调时，AccessViolationException

AccessViolationException when trying to call c# callback

本文关键字：AccessViolationException 回调 调用      更新时间：2023-10-16

我有这个简单的代码:

typedef void (__stdcall * OrdersCallback)(ordersTest*);
__declspec(dllexport) void InitializeCallbacks(long ordersCallbackAddress_) {
    OrdersCallback ordersCallbackFunction;
    std::cout << "current ordersCallbackFunction = " << ordersCallbackFunction << " address = " << &ordersCallbackFunction << std::endl;
    std::cout << "set ordersCallbackAddress_ = " << ordersCallbackAddress_ << std::endl;
    ordersCallbackFunction = (OrdersCallback) ordersCallbackAddress_;
    std::cout << "new ordersCallbackFunction = " << ordersCallbackFunction << " address = " << &ordersCallbackFunction << std::endl;
    ordersTest test;
    test.replID = 123;
    std::cout << "use ordersCallbackFunction = " << ordersCallbackFunction << " address = " << &ordersCallbackFunction << std::endl;
    ordersCallbackFunction(&test);
}

当回调调用时，引发AccessViolationException:

current ordersCallbackFunction = 000007F92BC354E0 address = 0000009785D1EC68
set ordersCallbackAddress_ = -2043003524
new ordersCallbackFunction = FFFFFFFF863A3D7C address = 0000009785D1EC68
use ordersCallbackFunction = FFFFFFFF863A3D7C address = 0000009785D1EC68
Unhandled Exception: System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

我不明白是什么错了，在另一个项目非常相似的代码工作。谢谢!

upd，更多代码:

    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
    public delegate void OrdersCallback(ref OrdersTest value);
    [DllImport("CGateNativeAdapter.dll"), SuppressUnmanagedCodeSecurity]
    public static extern void InitializeCallbacks(
        [MarshalAs(UnmanagedType.FunctionPtr)] OrdersCallback ordersSnapshotCallbackPointer);
        OrdersCallback ordersCallback =
            delegate(ref OrdersTest value)
            {
                Console.WriteLine("C# Orders call received = " +
                    " replID = " + value.replID);
            };
        InitializeCallbacks(ordersCallback);

您所显示的最明显的缺陷是您试图将64位指针传递为32位值，这显然无法工作。ordersCallbackAddress_参数声明为long，其宽度为32位。但你显然有一个64位的进程。这几乎可以肯定地解释您正在经历的错误。

请记住，在Windows上的c++中，long是32位宽。在c#中是64位宽。在任何情况下都不应该使用整型传递指针。如果你有一个指针，把你的函数设计成对指针进行操作。

您需要确保将ordersCallbackAddress_声明为指针大小。我不明白为什么不声明为OrdersCallback。

可能还有其他问题，但您没有显示太多代码。您没有在接口的托管端显示结构声明或任何内容。

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