将字符串从 Fortran dll 传递到 C#

Question

我正在尝试动态加载 Fortran dll 并将字符串从 fortran 传回 C#。在 fortran 代码中一切看起来都很好，但是当返回到 C# 时，字符串的值会丢失。相反，在 C# 中设置的初始值又回来了。我尝试使用“ref”关键字来获取要通过引用传递的字符串，但随后出现如下错误。我做错了什么？

运行时遇到致命错误。错误地址位于线程 0x2ac4 上的 0x709ce248。错误代码为 0xc0000005。此错误可能是 CLR 或用户代码的不安全或不可验证部分中的错误。此错误的常见来源包括 COM-interop 或 PInvoke 的用户封送错误，这可能会损坏堆栈。

Fortran 代码：

module FortLibInterface
implicit none

integer, parameter :: STR_LENGTH = 256

contains

subroutine GetString(Str)
    !DIR$ ATTRIBUTES DLLEXPORT::GetString
    !DIR$ ATTRIBUTES ALIAS: 'GetString' :: GetString
    !DIR$ ATTRIBUTES REFERENCE:: Str

    character(len=STR_LENGTH), intent(inout) :: Str

    Str = 'bcdef...'

end subroutine

end module

C#代码：

using System;
using System.Runtime.InteropServices;

namespace FortranCSTest
{
    class Program
    {
        static void Main(string[] args)
        {
            string dllPath = "C:\\Temp\\FortLib.dll";

            FortLibTest lib = new FortLibTest(dllPath);

            lib.MakeTestCall();
        }
    }

    public class FortLibTest
    {
        public const int STR_LENGTH = 256;

        public const string FortranFuncName = "GetString";

        private string pathToDll = null;

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern IntPtr LoadLibrary(String DllName);

        [DllImport("kernel32.dll")]
        private static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName);

        [DllImport("kernel32.dll")]
        private static extern bool FreeLibrary(IntPtr hModule);

        public FortLibTest(string FullPathToDll)
        {
            pathToDll = FullPathToDll;
        }

        [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
        private delegate void TypeGetStrInfo(char[] str);

        void GetStrInfo(char[] str)
        {
            IntPtr pDll = LoadLibrary(pathToDll);
            if (pDll != IntPtr.Zero)
            {
                IntPtr pFunc = GetProcAddress(pDll, FortranFuncName);
                if (pFunc != IntPtr.Zero)
                {
                    TypeGetStrInfo func = (TypeGetStrInfo)Marshal.GetDelegateForFunctionPointer(pFunc, typeof(TypeGetStrInfo));

                    func(str);
                }
                else
                {
                    //Something
                }

                FreeLibrary(pDll);
            }
            else
            {
                //Something
            }
        }

        public void MakeTestCall()
        {
            char[] str = new char[STR_LENGTH];

            str[0] = 'a'; 

            GetStrInfo(str);
        }
    }
}

Answer 1

供日后参考。我添加了 [In, Out] 并且一切正常。

 [DllImport(_dllName, CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
 public static extern void GetString([In, Out] char[] str);