scantar.go

package main

import (
	"archive/tar"
	"crypto/sha1"
	"encoding/hex"
	"fmt"
	"io"
	"os"
)

func main() {
	var src io.Reader

	if os.Args[1] == "-" {
		src = os.Stdin
	} else {
		s, err := os.Open(os.Args[1])
		if err != nil {
			panic(err)
		}
		src = s
	}
	r := tar.NewReader(src)
	for {
		hdr, err := r.Next()
		if err == io.EOF {
			fmt.Printf("done\n")
			break
		}
		if err != nil {
			panic(err)
		}
		fmt.Printf("%12d '%c' %s\n", hdr.Size, hdr.Typeflag, hdr.Name)
		hash := sha1.New()
		n, err := io.Copy(hash, r)
		if err != nil {
			panic(err)
		}
		digest := hex.EncodeToString(hash.Sum(nil))
		fmt.Printf("   ... copied %d bytes: %s\n", n, digest)
	}
}