The go language's method of splitting a file by a specified block size

This article demonstrates an example of how the go language splits files by a specified block size. Share with you for your reference. The details are as follows:

import (

 // "bufio"

 "flag"

 "fmt"

 "io"

 "os"

)

import "strconv"

var infile *string = flag.String("f", "Null", "please input a file name or dir.")

var size *string = flag.String("s", "0", "please input a dst file size.")

//func dataCopy(file *os.File, file *os.File)

func SplitFile(file *os.File, size int) {

 finfo, err := file.Stat()

 if err != nil {

  fmt.Println("get file info failed:", file, size)

 }

 fmt.Println(finfo, size)

 // Maximum copies at a time 1m

 bufsize := 1024 * 1024

 if size < bufsize {

  bufsize = size

 }

 buf := make([]byte, bufsize)

 num := (int(finfo.Size()) + size - 1) / size

 fmt.Println(num, len(buf))

 for i := 0; i < num; i++ {

  copylen := 0

  newfilename := finfo.Name() + strconv.Itoa(i)

  newfile, err1 := os.Create(newfilename)

  if err1 != nil {

   fmt.Println("failed to create file", newfilename)

  } else {

   fmt.Println("create file:", newfilename)

  }

  for copylen < size {

   n, err2 := file.Read(buf)

   if err2 != nil && err2 != io.EOF {

    fmt.Println(err2, "failed to read from:", file)

    break

   }

   if n <= 0 {

    break

   }

   //fmt.Println(n, len(buf))

   // Write files 

   w_buf := buf[:n]

   newfile.Write(w_buf)

   copylen += n

  }

 }

 return

}

func main() {

 flag.Parse()

 if *infile == "Null" {

  fmt.Println("no file to input")

  return

 }

 file, err := os.Open(*infile)

 if err != nil {

  fmt.Println("failed to open:", *infile)

 }

 defer file.Close()

 size, _ := strconv.Atoi(*size)

 SplitFile(file, size*1024)

}

I hope this article has been helpful to your programming of Go language.