sum.go

package main

import (
	"crypto/sha256"
	"encoding/hex"
	"io/ioutil"
	"os"
	"sync"

	"github.com/fatih/color"
)

var wg sync.WaitGroup

// HashResult represents the result of a single file checksum
type HashResult struct {
	Result string
	Error  error
}

// PrintFileHash get the checksum of the fileName file
// and show it's result or the related error
func PrintFileHash(fileName string, c chan HashResult) HashResult {
	defer wg.Done()
	green := color.New(color.FgGreen)
	red := color.New(color.FgRed)
	hasher := sha256.New()
	fileContent, err := ioutil.ReadFile(fileName)
	result := HashResult{}
	if err != nil {
		result = HashResult{Result: "", Error: err}
		c <- result
	} else {
		hasher.Write(fileContent)
		result = HashResult{Result: hex.EncodeToString(hasher.Sum(nil)), Error: nil}
	}
	if result.Error != nil {
		red.Println("KO > " + fileName + " - " + result.Error.Error())
	} else {
		green.Println("OK > " + fileName + " - " + result.Result)
	}
	c <- result
	return result
}

// HashAll analyze a directory and start a checksum of all the files resursively (if resursive is true)
// When the basePath is a file, only the file hash is computed
func HashAll(basePath string, recursive bool) {
	basePathInfo, _ := os.Stat(basePath)
	if basePathInfo.IsDir() {
		files, _ := ioutil.ReadDir(basePath)
		for _, file := range files {
			fullPath := basePath + "/" + file.Name()
			if !file.IsDir() && recursive {
				c := make(chan HashResult, 1)
				wg.Add(1)
				go PrintFileHash(fullPath, c)
			} else {
				HashAll(fullPath, false)
			}
		}
	} else {
		c := make(chan HashResult, 1)
		wg.Add(1)
		go PrintFileHash(basePath, c)
	}
}

func main() {
	HashAll(os.Args[1], true)
	wg.Wait()
}