package main

import (
    "archive/tar"
    "bytes"
    "compress/gzip"
    "fmt"
    "io"
    "io/ioutil"
    "os"
    "path/filepath"
)

func main() {
    modemBinDir := "bin"
    f, err := os.Create("test-file-handle.tar.gz")
    if err != nil {
        panic(err)
    }
    buff := new(bytes.Buffer)
    mw := io.MultiWriter(buff, f)
    // gzw := gzip.NewWriter(buff)
    gzw := gzip.NewWriter(mw)
    defer gzw.Close()

    tw := tar.NewWriter(gzw)
    defer tw.Close()
    if err := filepath.Walk(modemBinDir, func(path string, info os.FileInfo, err error) error {
        if err != nil {
            return err
        }

        header, err := tar.FileInfoHeader(info, path)
        if err != nil {
            return err
        }

        header.Name = path
        fmt.Println("Header name:", header.Name)
        if err := tw.WriteHeader(header); err != nil {
            return err
        }

        //Can't write folders, only their paths
        if !info.Mode().IsRegular() {
            return nil
        }

        f, err := os.Open(path)
        if err != nil {
            return err
        }

        if n, err := io.Copy(tw, f); err != nil {
            return err
        } else {
            fmt.Println("Wrote", n, "bytes to tar archive")
        }

        f.Close()
        return nil
    }); err != nil {
        panic(err)
    }
    ioutil.WriteFile("test-buffer.tar.gz", buff.Bytes(), 0644)
}