docker/fs: initial support for filesystem layers (adapted from image/layers.go)

Upstream-commit: 6372a1a0d0b6506f25db7ba3dbba1e65fd6deb2d
Component: engine

components/engine/image/layers.go

@@ -1,145 +0,0 @@
-package image
-
-import (
-	"errors"
-	"path"
-	"path/filepath"
-	"io"
-	"io/ioutil"
-	"os"
-	"os/exec"
-	"github.com/dotcloud/docker/future"
-)
-
-type LayerStore struct {
-	Root	string
-}
-
-func NewLayerStore(root string) (*LayerStore, error) {
-	abspath, err := filepath.Abs(root)
-	if err != nil {
-		return nil, err
-	}
-	return &LayerStore{
-		Root: abspath,
-	}, nil
-}
-
-func (store *LayerStore) List() []string {
-	files, err := ioutil.ReadDir(store.Root)
-	if err != nil {
-		return []string{}
-	}
-	var layers []string
-	for _, st := range files {
-		if st.IsDir() {
-			layers = append(layers, path.Join(store.Root, st.Name()))
-		}
-	}
-	return layers
-}
-
-func (store *LayerStore) Get(id string) string {
-	if !store.Exists(id) {
-		return ""
-	}
-	return store.layerPath(id)
-}
-
-func (store *LayerStore) rootExists() (bool, error) {
-	if stat, err := os.Stat(store.Root); err != nil {
-		if os.IsNotExist(err) {
-			return false, nil
-		}
-		return false, err
-	} else if !stat.IsDir() {
-		return false, errors.New("Not a directory: " + store.Root)
-	}
-	return true, nil
-}
-
-func (store *LayerStore) Init() error {
-	if exists, err := store.rootExists(); err != nil {
-		return err
-	} else if exists {
-		return nil
-	}
-	return os.Mkdir(store.Root, 0700)
-}
-
-
-func (store *LayerStore) Mktemp() (string, error) {
-	tmpName := future.RandomId()
-	tmpPath := path.Join(store.Root, "tmp-" + tmpName)
-	if err := os.Mkdir(tmpPath, 0700); err != nil {
-		return "", err
-	}
-	return tmpPath, nil
-}
-
-func (store *LayerStore) layerPath(id string) string {
-	return path.Join(store.Root, id)
-}
-
-
-func (store *LayerStore) AddLayer(archive io.Reader, stderr io.Writer, compression Compression) (string, error) {
-	tmp, err := store.Mktemp()
-	defer os.RemoveAll(tmp)
-	if err != nil {
-		return "", err
-	}
-	extractFlags := "-x"
-	if compression == Bzip2 {
-		extractFlags += "j"
-	} else if compression == Gzip {
-		extractFlags += "z"
-	}
-	untarCmd := exec.Command("tar", "-C", tmp, extractFlags)
-	untarW, err := untarCmd.StdinPipe()
-	if err != nil {
-		return "", err
-	}
-	untarStderr, err := untarCmd.StderrPipe()
-	if err != nil {
-		return "", err
-	}
-	go io.Copy(stderr, untarStderr)
-	untarStdout, err := untarCmd.StdoutPipe()
-	if err != nil {
-		return "", err
-	}
-	go io.Copy(stderr, untarStdout)
-	untarCmd.Start()
-	hashR, hashW := io.Pipe()
-	job_copy := future.Go(func() error {
-		_, err := io.Copy(io.MultiWriter(hashW, untarW), archive)
-		hashW.Close()
-		untarW.Close()
-		return err
-	})
-	id, err := future.ComputeId(hashR)
-	if err != nil {
-		return "", err
-	}
-	if err := untarCmd.Wait(); err != nil {
-		return "", err
-	}
-	if err := <-job_copy; err != nil {
-		return "", err
-	}
-	layer := store.layerPath(id)
-	if !store.Exists(id) {
-		if err := os.Rename(tmp, layer); err != nil {
-			return "", err
-		}
-	}
-	return layer, nil
-}
-
-func (store *LayerStore) Exists(id string) bool {
-	st, err := os.Stat(store.layerPath(id))
-	if err != nil {
-		return false
-	}
-	return st.IsDir()
-}