package main

import "fmt"
import "crypto/sha256"
import "io"
import "log"
import "os"
import "path/filepath"

func walk(path string, info os.FileInfo, err error) error {
	if err != nil {
		log.Fatalln(err)
		return err
	}

	if info.IsDir() {
		return nil
	} else {
		h, err := sha256File(path)
		if err != nil {
			return err
		}
		fmt.Printf("SHA256 (%s) =  %x\n", info.Name(), h)
	}
	return nil
}

func sha256File(path string) ([]byte, error) {
	f, err := os.Open(path)
	if err != nil {
		log.Fatalln(err)
		return nil, err
	}
	defer f.Close()
	h := sha256.New()
	io.Copy(h, f)
	return h.Sum(nil), nil
}

func main() {
	if len(os.Args) < 2 {
		log.Fatalln("Usage shadir file")
	}
	if err := filepath.Walk(os.Args[1], walk); err != nil {
		panic(err)
	}

}