GoHash/pkg/hash/hash.go

package hash

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"io"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strings"
	"time"
)

const FDHASHFILENAME = ".fdhashes3"

var dirHashes map[string]Fdhashes

// Fdhashes struct for holding all informations about one folder.
type Fdhashes struct {
	Path   string
	Hashes map[string]string
	Times  map[string]time.Time
	Dirty  bool
}

func init() {
	dirHashes = make(map[string]Fdhashes)
}

func LoadHashfile(fileStr string) (*Fdhashes, error) {
	fileInfo, err := os.Stat(fileStr)
	if err != nil {
		return nil, err
	}
	if fileInfo.IsDir() {
		fileStr = filepath.Join(fileStr, FDHASHFILENAME)
	}

	dir, name := filepath.Split(fileStr)
	if strings.ToLower(name) != FDHASHFILENAME {
		fileStr = filepath.Join(dir, FDHASHFILENAME)
	}
	dir = filepath.ToSlash(filepath.Clean(dir))
	var data Fdhashes
	file, err := ioutil.ReadFile(fileStr)
	if err != nil {
		return nil, err
	}
	err = json.Unmarshal([]byte(file), &data)
	if err != nil {
		return nil, err
	}
	if data.Path != dir {
		data.Path = dir
		data.Dirty = true
	}
	return &data, nil
}

func GetHash(path string, name string) (string, error) {
	fileInfo, err := os.Stat(path)
	if err != nil {
		return "", err
	}
	if !fileInfo.IsDir() {
		path, _ = filepath.Split(path)
	}
	path = filepath.Clean(path)
	fdHashes, ok := dirHashes[path]
	if !ok {
		fh, err := LoadHashfile(path)
		if err != nil {
			return "", err
		}
		dirHashes[path] = *fh
		fdHashes = *fh
	}

	hash := fdHashes.Hashes[name]
	return hash, nil
}

func GetFileHash(fileStr string) string {
	f, err := os.Open(fileStr)
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	h := sha256.New()
	if _, err := io.Copy(h, f); err != nil {
		log.Fatal(err)
	}
	return hex.EncodeToString(h.Sum(nil))
}