ReadString 读取 EOF 时如何打破循环？

问：

我正在为服务器和客户端编写简单的代码，这是服务器部分。我想一次从套接字中读取一行消息并将其写入 newfile。但是，如果代码读取 EOF，则代码将停止运行。我想知道如何打破循环并继续运行下面的代码。 谢谢！

package main

import "fmt"
import "bufio"
import "net"
import "os"
import "log"
//import "strings" 


func check(e error) {
   if e != nil {
   panic(e) 
   }
}

func main() {
   fmt.Println("Launching server...")
   ln, _ := net.Listen("tcp", ":12003") 
   conn, _ := ln.Accept()
   defer ln.Close()
   defer conn.Close()

   //read file size(string)
   reader1 := bufio.NewReader(conn) 
   m_size, err1 := reader1.ReadString('\n')  
   check(err1)

   //print file size
   fmt.Printf("Upload file size: %s", m_size)

   //create new file
   out_file := "whatever.txt"
   newfile, err2 := os.Create(out_file) 
   check(err2)
   defer newfile.Close()


   //read and write line to new file
   writer1 := bufio.NewWriter(newfile)
   var i = 1
   line, err3 := reader1.ReadString('\n')
   check(err3)
   for err3 == nil {
       writer1.WriteString(fmt.Sprintf("%d %s", i, line)) 
       line, err3 = reader1.ReadString('\n')
       if err3 != nil { 
         break
       }
       i += 1
   }
   writer1.Flush()
   
   // get the new file's size and print
   stats, errr := os.Stat(out_file)
   if errr != nil {
      log.Fatal(errr)
   }
   fmt.Printf("Output file size: %d\n", stats.Size())

   // send message back to client
   writer2 := bufio.NewWriter(conn)
   m_size = strings.Replace(m_size, "\n", "", -1)
   newline := fmt.Sprintf("%s bytes received, %d bytes file generated",m_size,stats.Size()) 
   _, errw := writer2.WriteString(newline)
   check(errw)
   writer2.Flush()
}