从C＃中的C-DLL调用带有struct参数的函数时出现访问冲突错误

Question

我对基于c的DLL中的函数进行了以下定义（没有可用的源代码）：

uint MakeReference(MemBlock* ipReferenceMemBlock);

MemBlock定义为：

typedef struct {
    HANDLE_TAG dTag;
    long dLength;
    BYTE* dpReference;
} MemBlock;

HANDLE_TAG定义为：

typedef char HANDLE_TAG[10 + 1];

我在C＃Wrapper类中对此的看法是：

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct MemBlock
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 11)]
    public string dTag;
    public uint dLength;
    [MarshalAs(UnmanagedType.LPStr)]
    public string dpReference;
}



[DllImport("lib.dll", CharSet = CharSet.Ansi, EntryPoint = "MakeReference@24", CallingConvention = CallingConvention.StdCall)]
public static extern uint MakeReference(ref IntPtr pDDipMemBlock);

public static uint FAPIMakeReference(ref MemBlock ipMemBlock)
    {
        uint error = 0;
        IntPtr pDDipMemBlock = Marshal.AllocHGlobal(Marshal.SizeOf(ipMemBlock));
        try
        {
            Marshal.StructureToPtr(ipMemBlock, pDDipMemBlock, false);
            error = MakeReferenceEx(ref pDDipMemBlock);
            ipMemBlock = (MemBlock)Marshal.PtrToStructure(pDDipMemBlock, typeof(MemBlock));
        }
        finally
        {
            Marshal.FreeHGlobal(pDDipMemBlock);

        }
        return error;
    }

用以下方式调用：

MemBlock refMemBlock = new MemBlock();
uint error = MakeReferenceEx(ref refMemBlock);

导致访问冲突期望