dotcloud/docker

package chrootarchive // import "github.com/docker/docker/pkg/chrootarchive"

import (
    "fmt"
    "io"
    "path/filepath"

    "github.com/docker/docker/pkg/archive"
)

// applyLayerHandler parses a diff in the standard layer format from `layer`, and
// applies it to the directory `dest`. Returns the size in bytes of the
// contents of the layer.
func applyLayerHandler(dest string, layer io.Reader, options *archive.TarOptions, decompress bool) (size int64, err error) {
    if decompress {
        decompressed, err := archive.DecompressStream(layer)
        if err != nil {
            return 0, err
        }
        defer decompressed.Close()

        layer = decompressed
    }

    // Ensure it is a Windows-style volume path
    dest = addLongPathPrefix(filepath.Clean(dest))
    s, err := archive.UnpackLayer(dest, layer, nil)
    if err != nil {
        return 0, fmt.Errorf("ApplyLayer %s failed UnpackLayer to %s: %s", layer, dest, err)
    }

    return s, nil
}