从 C# 传递结构作为参数调用非托管 DLL

Question

我有一个 DLL 文件，但没有类型库和文档。我所拥有的是使用它的 Delphi (Pascal) 代码。我正在尝试使用 .Net 5 C# 调用此 DLL。

我得到的错误是

System.AccessViolationException: 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'

这是我的尝试：

    [StructLayout(LayoutKind.Sequential)]
    public struct MyDLLQuery
    {
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
        public string Frame;

        public int Width { get; set; }

        public double Cost { get; set; }
        ...
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct MyDLLResult
    {
        public int NumTubes { get; set; }
        public double Spacing { get; set; }

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
        public string Material;
        ...
    }

    internal static class MyDLLWrapper
    {
        const string DLL = @"bin\MyDLL.dll";
        private static CallbackDelegate delegateInstance;

        [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
        public delegate void CallbackDelegate();
    
        [DllImport(DLL, CallingConvention = CallingConvention.StdCall)]
        private static extern void CalculateData(MyDLLQuery indata, out MyDLLResult outdata, CallbackDelegate f);

        internal static void Query()
        {
            MyDLLQuery indata = new MyDLLQuery();
            indata.Frame = "G";
            indata.Width = 1300; 
            indata.Cost = 50.0; 
            ...

            MyDLLResult outdata = new MyDLLResult();
    
            delegateInstance = MyFunc;
    
            CalculateData(indata, out outdata, delegateInstance);
        }

        public static void MyFunc()
        {
            
        }
    }

这里是 Delphi 调用相同 DLL 的代码（确实有效）：

    TInParams = record
        Frame: array [0..15] of Char;
        Width: Integer;
        Cost: Double;
        ...

    TOutParams = record
        NumTubes: Integer;
        Spacing: Double;
        Material: array [0..15] of Char;
        ...


    TInfoCallBackProcedure = procedure() cdecl;

    const LIBNAME = 'MyDLL.dll';

    procedure CalculateData(InData: TInParams; var OutData: TOutParams; Callback: TInfoCallbackProcedure); stdcall external LIBNAME;


    var
        InParams: TInParams;
        OutParams: TOutParams;


    SetInData(sourceData, InParams); // assigns a value to all fields in InParams
    FillChar(OutParams, SizeOf(OutParams), 0);

    CalculateData(InParams, OutParams, Callback); // No callback = nil

我已确保结构中的所有字段的顺序与 Delphi 代码中的顺序相同。

Answer 1

终于解决了这个问题。我之前曾尝试在 DLL 调用中使用 Charset unicode，但我错过了在结构上设置它：

[DllImport(DLL, CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Unicode)]
private static extern void CalculateData(MyDLLQuery indata, out MyDLLResult outdata, CallbackDelegate f);

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct MyDLLQuery
...

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct MyDLLResult
...

Answer 2

    StructLayout(LayoutKind.Sequential, Pack = 1, CharSet = CharSet.Unicode)]
    public struct Result
    {
        //SizeCount bezieht sich anscheinden auf Char (hier 2 Byte) und
        // nicht auf die Bytegröße des Felds
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 12)] public string BIC; //Delphi: array[0..10] of char
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 35)] public string IBAN; //Delphi: array[0..33] of char
        [MarshalAs(UnmanagedType.I4)] public BACIbanKonverterStatus Status;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 201)] public string StatusMessage;
        //Delphi: array[0..199] of char

        [MarshalAs(UnmanagedType.Bool)] //Delphi: Longbool
        public bool Success;
    }

已在 Delphi 中实现如下：

 TRecIban=packed record
public
  Bic          : array[0..10] of char;
  Filler_1     : Char;
  Iban         : array[0..33] of char;
  Filler_2     : Char;
  Status       : integer;
  StatusMessage: array[0..199] of char;
  Filler_3     : Char;
  Success      : Longbool;
end

C#中字符串的结尾映射到Delphi中的Filler_X。今天我将在 C# 中编组 [MarshalAs (UnmanagedType.LPWStr)]。在 Delphi 中，我会使用 PChar。那么填充物就不用了

从 C# 传递结构作为参数调用非托管 DLL

Calling an unmanaged DLL from C# passing structs as parameters

c#

delphi

dll

unmanaged