package tgz
import (
"archive/tar"
"compress/gzip"
"fmt"
"io"
"io/ioutil"
"os"
)
const (
useDefaultTempDir = ""
tmpPrefix = "tmp-tgz-"
)
// Extract decompress a gziped tarball into a new temporal directory
// created just for this purpose.
//
// On success, the path of the newly created directory and a nil error
// is returned.
//
// A non-nil error is returned if the method fails to complete. The
// returned path will be an empty string if no information was extracted
// before the error and the temporal directory has not been created.
// Otherwise, a non-empty string with the temporal directory holding
// whatever information was extracted before the error is returned.
func Extract(tgz string) (d string, err error) {
f, err := os.Open(tgz)
if err != nil {
return "", err
}
defer func() {
errClose := f.Close()
if err == nil {
err = errClose
}
}()
d, err = ioutil.TempDir(useDefaultTempDir, tmpPrefix)
if err != nil {
return "", err
}
tar, err := zipTarReader(f)
if err != nil {
return d, err
}
if err = unTar(tar, d); err != nil {
return d, err
}
return d, nil
}
func zipTarReader(r io.Reader) (*tar.Reader, error) {
zip, err := gzip.NewReader(r)
if err != nil {
return nil, err
}
return tar.NewReader(zip), nil
}
func unTar(src *tar.Reader, dstPath string) error {
for {
header, err := src.Next()
if err != nil {
if err == io.EOF {
break
}
return err
}
dst := dstPath + "/" + header.Name
mode := os.FileMode(header.Mode)
switch header.Typeflag {
case tar.TypeDir:
err := os.MkdirAll(dst, mode)
if err != nil {
return err
}
case tar.TypeReg:
err := makeFile(dst, mode, src)
if err != nil {
return err
}
default:
return fmt.Errorf("Unable to untar type : %c in file %s",
header.Typeflag, header.Name)
}
}
return nil
}
func makeFile(path string, mode os.FileMode, contents io.Reader) (err error) {
w, err := os.Create(path)
if err != nil {
return err
}
defer func() {
errClose := w.Close()
if err == nil {
err = errClose
}
}()
_, err = io.Copy(w, contents)
if err != nil {
return err
}
if err = os.Chmod(path, mode); err != nil {
return err
}
return nil
}