我的C#app如何测试用户是否具有对网络共享的"读取"访问权限？

using System;
using System.IO;
using System.Security.Principal;

class Program
{
    static void Main(string[] args)
    {
        string path = @"\\server\share\file.txt";

        if (File.Exists(path))
        {
            Console.WriteLine("File exists.");
        }
        else
        {
            Console.WriteLine("File does not exist.");
            return;
        }

        WindowsIdentity currentIdentity = WindowsIdentity.GetCurrent();
        WindowsPrincipal principal = new WindowsPrincipal(currentIdentity);

        if (principal.IsInRole(WindowsBuiltInRole.Administrator))
        {
            Console.WriteLine("User has read access.");
        }
        else
        {
            Console.WriteLine("User does not have read access.");
        }
    }
}