using System;
using System.IO;
using System.Net;
using System.Net.Sockets;

namespace nulldd
{
    class nulldd
    {
        static void Main(string[] args)
        {
            int size;
            if ((args.Length != 2) || !int.TryParse(args[1], out size))
            {
                Console.Error.WriteLine("usage: nulldd <file> <size in MiB>");
                return;
            }

            byte[] zeros = new byte[1024 * 1024];
            Array.Clear(zeros, 0, zeros.Length);

            Socket servsock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            servsock.Bind(new IPEndPoint(IPAddress.Any, 6666));
            servsock.Listen(512);
            servsock.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);

            for (int round = 1; ; round++)
            {
                Socket client = servsock.Accept();
                FileStream file = new FileStream(args[0], FileMode.OpenOrCreate, FileAccess.Write,
                    FileShare.None, zeros.Length, FileOptions.WriteThrough);
                for (int i = 0; i < size; i++)
                    file.Write(zeros, 0, zeros.Length);
                file.Flush();
                file.Close();
                Console.WriteLine("#" + round);
                client.Close();
            }
        }
    }
}