func applyLayer() {
var (
root = "/"
tmpDir = ""
err error
)
runtime.LockOSThread()
flag.Parse()
if runtime.GOOS != "windows" {
if err := chroot(flag.Arg(0)); err != nil {
fatal(err)
}
// We need to be able to set any perms
oldmask, err := system.Umask(0)
defer system.Umask(oldmask)
if err != nil {
fatal(err)
}
} else {
// As Windows does not support chroot or umask, we use the directory
// passed in which will be <pathto>\docker-buildnnnnnnnn instead of
// the 'chroot-root', "/"
root = flag.Arg(0)
}
if tmpDir, err = ioutil.TempDir(root, "temp-docker-extract"); err != nil {
fatal(err)
}
os.Setenv("TMPDIR", tmpDir)
size, err := archive.UnpackLayer(root, os.Stdin)
os.RemoveAll(tmpDir)
if err != nil {
fatal(err)
}
encoder := json.NewEncoder(os.Stdout)
if err := encoder.Encode(applyLayerResponse{size}); err != nil {
fatal(fmt.Errorf("unable to encode layerSize JSON: %s", err))
}
flush(os.Stdout)
flush(os.Stdin)
os.Exit(0)
}
// ApplyLayer 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 ApplyLayer(dest string, layer ArchiveReader) (int64, error) {
dest = filepath.Clean(dest)
// We need to be able to set any perms
oldmask, err := system.Umask(0)
if err != nil {
return 0, err
}
defer system.Umask(oldmask) // ignore err, ErrNotSupportedPlatform
layer, err = DecompressStream(layer)
if err != nil {
return 0, err
}
return UnpackLayer(dest, layer)
}