在C＃中使用Delphi DLL [英] Using Delphi DLL in C#

问题描述

我有一个用Delphi（未知版本）编写的第三方神秘dll，这是delphi中的工作示例（过去2009），迫切需要在我的C＃代码中使用所说的dll，并且几乎没有相关的知识来做到这一点。

I have a third party "mystery dll" written with Delphi(unknown version), working example in delphi (past 2009), dire need to use said dll in my C# code, and almost no relevant knowledge on how to do it.

下面是使用此dll的Delpi示例：

Here is Delpi example in using this dll:

type
TD_Query = function(host: WideString; port : Word;pud,query : WideString):WideString; stdcall;
procedure TForm11.Button6Click(Sender: TObject);
var
   Handle         : LongWord;
   D_Query        : TD_Query;
   sss            : WideString;
begin

 Handle := LoadLibrary('kobrasdk.dll');
 sss:='';
 if Handle <> 0 then
 begin
  @D_Query := GetProcAddress(Handle, 'D_Query');
  sss:=D_Query('host',8201,'pud','query');
  FreeLibrary(Handle);
 end;
end;

这是我在C＃中解释它的尝试：

And here is my attempts to interpret it in C#:

class Program
{
    [DllImport("C:\\Games\\kobrasdk.dll", CallingConvention = CallingConvention.StdCall,
        CharSet = CharSet.Ansi)]
    [return: MarshalAs(UnmanagedType.LPStr)]
    public static extern string D_Query(string host, ushort port, string pud, string query);


    static void Main(string[] args)
    {
        D_Query("test", 8201, "test", "test");
    }
}

不幸的是，我有一个错误：试图读取或写入受保护的内存。通常这表明其他内存已损坏。

Unfortunately, what I have is an error: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

根据我白天的读物，我可能对返回类型或参数类型有所怀疑。

From what I read during the day, I probably fudged up with return type, or parameter types. Help?

推荐答案

Delphi ABI在某些类型上不同于Microsoft ABI。 Delphi WideString 是托管类型（在Delphi术语中），而返回类型使用与Microsoft工具不兼容的ABI。

The Delphi ABI differs from the Microsoft ABI for certain types. A Delphi WideString is a managed type (in Delphi terminology) and as return types use an ABI that is incompatible with Microsoft tools.

Delphi ABI将托管返回类型转换为隐藏的 var 参数。因此编译器将转换为：

The Delphi ABI translates a managed return type into a hidden var parameter. So the compiler transforms:

function(host: WideString; port: Word; pud, query: WideString): WideString; stdcall;

进入

procedure(var result: WideString; host: WideString; port: Word; pud, query: WideString); 
  stdcall;

因此，您可以通过以转换后的形式导入C＃来访问原始的Delphi函数。

You can therefore access your original Delphi function from C# by importing the function in its transformed guise.

[DllImport(@"...", CallingConvention = CallingConvention.StdCall)]
public static extern void My_D_Query(
    [MarshalAs(UnmanagedType.BStr)]
    out string result,
    [MarshalAs(UnmanagedType.BStr)]
    string host,
    ushort port,
    [MarshalAs(UnmanagedType.BStr)]
    string pud,
    [MarshalAs(UnmanagedType.BStr)]
    string query
);

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