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zip.go
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zip.go
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package scytale
import (
"archive/zip"
"crypto/md5"
"errors"
"fmt"
"io"
"os"
"path"
"path/filepath"
"sync"
)
type ZipArchive struct {
sync.Mutex
password string
status Status
}
type Status int
const (
Running Status = iota
Idle
)
// WalkFunc is the type of the function called for each file added to the archive.
type WalkFunc func(path string, info os.FileInfo, current, total int) error
func NewZipArchive(password string) *ZipArchive {
return &ZipArchive{
password: password,
status: Idle,
}
}
func (a *ZipArchive) SetPassword(pwd string) {
a.password = pwd
}
func (a *ZipArchive) Status() Status {
a.Lock()
defer a.Unlock()
return a.status
}
// Cancel stops the current processing, if any.
func (a *ZipArchive) Cancel() {
a.Lock()
defer a.Unlock()
a.status = Idle
}
// Create creates a new ZIP output archive given a list of input files. fn() is
// called just after a file has been encrypted and added to the archive. Set random
// to true to rename file with their md5 checksum.
func (a *ZipArchive) Create(output string, files []string, fn WalkFunc, random bool) error {
a.Lock()
a.status = Running
a.Unlock()
defer func() {
a.Lock()
a.status = Idle
a.Unlock()
}()
out, err := os.Create(output)
if err != nil {
return err
}
tw := zip.NewWriter(out)
defer tw.Close()
aes, err := NewAES(a.password)
if err != nil {
return err
}
nb := len(files)
for u, file := range files {
f, err := os.Open(file)
if err != nil {
return err
}
info, err := f.Stat()
if err != nil {
f.Close()
return err
}
info.IsDir()
hdr, err := zip.FileInfoHeader(info)
if random {
m := md5.New()
io.WriteString(m, hdr.Name)
hdr.Name = fmt.Sprintf("%x%s", m.Sum(nil), filepath.Ext(hdr.Name))
}
fw, err := tw.CreateHeader(hdr)
if err != nil {
f.Close()
return err
}
if err := aes.EncryptFile(f, fw); err != nil {
f.Close()
return err
}
f.Close()
if err := fn(file, info, u+1, nb); err != nil {
return err
}
if a.status == Idle {
// Processing has been cancelled
break
}
}
return nil
}
// ExtractAll extracts all encrypted files from zip archive. The
// resulting files are decrypted using the provided password.
func (a *ZipArchive) ExtractAll(archive, outputDir string) error {
a.Lock()
a.status = Running
a.Unlock()
defer func() {
a.Lock()
a.status = Idle
a.Unlock()
}()
if _, err := os.Stat(outputDir); err != nil {
return err
}
tr, err := zip.OpenReader(archive)
if err != nil {
return err
}
defer tr.Close()
aes, err := NewAES(a.password)
if err != nil {
return err
}
for _, fi := range tr.File {
f, err := os.Create(path.Join(outputDir, fi.Name))
if err != nil {
f.Close()
return err
}
rc, err := fi.Open()
if err != nil {
return err
}
if err := aes.DecryptFile(rc, f); err != nil {
f.Close()
return err
}
f.Close()
rc.Close()
if a.status == Idle {
// Processing has been cancelled
break
}
}
return nil
}
// ExtractAt extracts a single file at position pos from zip archive. The
// resulting file is decrypted using the provided password.
func (a *ZipArchive) ExtractAt(pos int, archive, outputDir string) error {
a.Lock()
a.status = Running
a.Unlock()
defer func() {
a.Lock()
a.status = Idle
a.Unlock()
}()
if _, err := os.Stat(outputDir); err != nil {
return err
}
tr, err := zip.OpenReader(archive)
if err != nil {
return err
}
defer tr.Close()
if pos > len(tr.File)-1 || pos < 0 {
return errors.New(fmt.Sprintf("position %d out of bounds (%d files in archive)", pos, len(tr.File)))
}
aes, err := NewAES(a.password)
if err != nil {
return err
}
at := tr.File[pos]
f, err := os.Create(path.Join(outputDir, at.Name))
if err != nil {
f.Close()
return err
}
rc, err := at.Open()
if err != nil {
return err
}
if err := aes.DecryptFile(rc, f); err != nil {
f.Close()
return err
}
f.Close()
rc.Close()
return nil
}