Example #1
0
func writeTarFromLayer(r hcsshim.LayerReader, w io.Writer) error {
	t := tar.NewWriter(w)
	for {
		name, size, fileInfo, err := r.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}
		if fileInfo == nil {
			// Write a whiteout file.
			hdr := &tar.Header{
				Name: filepath.ToSlash(filepath.Join(filepath.Dir(name), archive.WhiteoutPrefix+filepath.Base(name))),
			}
			err := t.WriteHeader(hdr)
			if err != nil {
				return err
			}
		} else {
			err = backuptar.WriteTarFileFromBackupStream(t, r, name, size, fileInfo)
			if err != nil {
				return err
			}
		}
	}
	return t.Close()
}
Example #2
0
// exportLayer generates an archive from a layer based on the given ID.
func (d *Driver) exportLayer(id string, parentLayerPaths []string) (archive.Archive, error) {
	if hcsshim.IsTP4() {
		// Export in TP4 format to maintain compatibility with existing images and
		// because ExportLayer is somewhat broken on TP4 and can't work with the new
		// scheme.
		tempFolder, err := ioutil.TempDir("", "hcs")
		if err != nil {
			return nil, err
		}
		defer func() {
			if err != nil {
				os.RemoveAll(tempFolder)
			}
		}()

		if err = hcsshim.ExportLayer(d.info, id, tempFolder, parentLayerPaths); err != nil {
			return nil, err
		}
		archive, err := archive.Tar(tempFolder, archive.Uncompressed)
		if err != nil {
			return nil, err
		}
		return ioutils.NewReadCloserWrapper(archive, func() error {
			err := archive.Close()
			os.RemoveAll(tempFolder)
			return err
		}), nil
	}

	var r hcsshim.LayerReader
	r, err := hcsshim.NewLayerReader(d.info, id, parentLayerPaths)
	if err != nil {
		return nil, err
	}

	archive, w := io.Pipe()
	go func() {
		err := writeTarFromLayer(r, w)
		cerr := r.Close()
		if err == nil {
			err = cerr
		}
		w.CloseWithError(err)
	}()

	return archive, nil
}
Example #3
0
// exportLayer generates an archive from a layer based on the given ID.
func (d *Driver) exportLayer(id string, parentLayerPaths []string) (archive.Archive, error) {
	var r hcsshim.LayerReader
	r, err := hcsshim.NewLayerReader(d.info, id, parentLayerPaths)
	if err != nil {
		return nil, err
	}

	archive, w := io.Pipe()
	go func() {
		err := writeTarFromLayer(r, w)
		cerr := r.Close()
		if err == nil {
			err = cerr
		}
		w.CloseWithError(err)
	}()

	return archive, nil
}