Get the MD5 hash of a directory's content (recursively)

md5recursive.go

// MIT License <https://opensource.org/licenses/MIT> - Copyright (c) 2019 Miguel Dorta
package main

import (
	"crypto/md5"
	"fmt"
	"io"
	"os"
	"path/filepath"
)

func main() {
	if len(os.Args) != 2 {
		fmt.Printf("Usage:    %s <path>\n", os.Args[0])
		os.Exit(1)
	}
	listDirRecursive(os.Args[1])
}

func listDir(path string) ([]os.FileInfo, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	return f.Readdir(-1)
}

func listDirRecursive(path string) {
	list, err := listDir(path)
	if err != nil {
		fmt.Fprintf(os.Stderr, "error reading %s: %s\n", path, err.Error())
		return
	}

	for _, element := range list {
		eMode := element.Mode()
		ePath := filepath.Join(path, element.Name())

		if eMode.IsDir() {
			listDirRecursive(ePath)
		} else if eMode.IsRegular() {
			h, err := hashFile(ePath)
			if err != nil {
				fmt.Fprintf(os.Stderr, "error reading %s: %s\n", ePath, err.Error())
				continue
			}
			fmt.Printf("%x %s\n", h, ePath)
		} else {
			fmt.Fprintf(os.Stderr, "error reading %s: type not supported\n", ePath)
			continue
		}
	}
}

func hashFile(path string) ([]byte, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	h := md5.New()

	if _, err := io.Copy(h, f); err != nil {
		return nil, err
	}

	return h.Sum(nil), nil
}