1 files changed, 401 insertions, 0 deletions
diff --git a/runtime/graphdriver/aufs/aufs.go b/runtime/graphdriver/aufs/aufs.go
new file mode 100644
index 0000000000..401bbd8c86
--- /dev/null
+++ b/runtime/graphdriver/aufs/aufs.go
@@ -0,0 +1,401 @@
+/*
+
+aufs driver directory structure
+
+.
+├── layers // Metadata of layers
+│   ├── 1
+│   ├── 2
+│   └── 3
+├── diffs  // Content of the layer
+│   ├── 1  // Contains layers that need to be mounted for the id
+│   ├── 2
+│   └── 3
+└── mnt    // Mount points for the rw layers to be mounted
+    ├── 1
+    ├── 2
+    └── 3
+
+*/
+
+package aufs
+
+import (
+	"bufio"
+	"fmt"
+	"github.com/dotcloud/docker/archive"
+	mountpk "github.com/dotcloud/docker/pkg/mount"
+	"github.com/dotcloud/docker/runtime/graphdriver"
+	"github.com/dotcloud/docker/utils"
+	"os"
+	"os/exec"
+	"path"
+	"strings"
+	"sync"
+)
+
+var (
+	ErrAufsNotSupported = fmt.Errorf("AUFS was not found in /proc/filesystems")
+)
+
+func init() {
+	graphdriver.Register("aufs", Init)
+}
+
+type Driver struct {
+	root       string
+	sync.Mutex // Protects concurrent modification to active
+	active     map[string]int
+}
+
+// New returns a new AUFS driver.
+// An error is returned if AUFS is not supported.
+func Init(root string) (graphdriver.Driver, error) {
+	// Try to load the aufs kernel module
+	if err := supportsAufs(); err != nil {
+		return nil, err
+	}
+	paths := []string{
+		"mnt",
+		"diff",
+		"layers",
+	}
+
+	a := &Driver{
+		root:   root,
+		active: make(map[string]int),
+	}
+
+	// Create the root aufs driver dir and return
+	// if it already exists
+	// If not populate the dir structure
+	if err := os.MkdirAll(root, 0755); err != nil {
+		if os.IsExist(err) {
+			return a, nil
+		}
+		return nil, err
+	}
+
+	for _, p := range paths {
+		if err := os.MkdirAll(path.Join(root, p), 0755); err != nil {
+			return nil, err
+		}
+	}
+	return a, nil
+}
+
+// Return a nil error if the kernel supports aufs
+// We cannot modprobe because inside dind modprobe fails
+// to run
+func supportsAufs() error {
+	// We can try to modprobe aufs first before looking at
+	// proc/filesystems for when aufs is supported
+	exec.Command("modprobe", "aufs").Run()
+
+	f, err := os.Open("/proc/filesystems")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	s := bufio.NewScanner(f)
+	for s.Scan() {
+		if strings.Contains(s.Text(), "aufs") {
+			return nil
+		}
+	}
+	return ErrAufsNotSupported
+}
+
+func (a Driver) rootPath() string {
+	return a.root
+}
+
+func (Driver) String() string {
+	return "aufs"
+}
+
+func (a Driver) Status() [][2]string {
+	ids, _ := loadIds(path.Join(a.rootPath(), "layers"))
+	return [][2]string{
+		{"Root Dir", a.rootPath()},
+		{"Dirs", fmt.Sprintf("%d", len(ids))},
+	}
+}
+
+// Exists returns true if the given id is registered with
+// this driver
+func (a Driver) Exists(id string) bool {
+	if _, err := os.Lstat(path.Join(a.rootPath(), "layers", id)); err != nil {
+		return false
+	}
+	return true
+}
+
+// Three folders are created for each id
+// mnt, layers, and diff
+func (a *Driver) Create(id, parent string, mountLabel string) error {
+	if err := a.createDirsFor(id); err != nil {
+		return err
+	}
+	// Write the layers metadata
+	f, err := os.Create(path.Join(a.rootPath(), "layers", id))
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	if parent != "" {
+		ids, err := getParentIds(a.rootPath(), parent)
+		if err != nil {
+			return err
+		}
+
+		if _, err := fmt.Fprintln(f, parent); err != nil {
+			return err
+		}
+		for _, i := range ids {
+			if _, err := fmt.Fprintln(f, i); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func (a *Driver) createDirsFor(id string) error {
+	paths := []string{
+		"mnt",
+		"diff",
+	}
+
+	for _, p := range paths {
+		if err := os.MkdirAll(path.Join(a.rootPath(), p, id), 0755); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Unmount and remove the dir information
+func (a *Driver) Remove(id string) error {
+	// Protect the a.active from concurrent access
+	a.Lock()
+	defer a.Unlock()
+
+	if a.active[id] != 0 {
+		utils.Errorf("Warning: removing active id %s\n", id)
+	}
+
+	// Make sure the dir is umounted first
+	if err := a.unmount(id); err != nil {
+		return err
+	}
+	tmpDirs := []string{
+		"mnt",
+		"diff",
+	}
+
+	// Atomically remove each directory in turn by first moving it out of the
+	// way (so that docker doesn't find it anymore) before doing removal of
+	// the whole tree.
+	for _, p := range tmpDirs {
+
+		realPath := path.Join(a.rootPath(), p, id)
+		tmpPath := path.Join(a.rootPath(), p, fmt.Sprintf("%s-removing", id))
+		if err := os.Rename(realPath, tmpPath); err != nil && !os.IsNotExist(err) {
+			return err
+		}
+		defer os.RemoveAll(tmpPath)
+	}
+
+	// Remove the layers file for the id
+	if err := os.Remove(path.Join(a.rootPath(), "layers", id)); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	return nil
+}
+
+// Return the rootfs path for the id
+// This will mount the dir at it's given path
+func (a *Driver) Get(id string) (string, error) {
+	ids, err := getParentIds(a.rootPath(), id)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return "", err
+		}
+		ids = []string{}
+	}
+
+	// Protect the a.active from concurrent access
+	a.Lock()
+	defer a.Unlock()
+
+	count := a.active[id]
+
+	// If a dir does not have a parent ( no layers )do not try to mount
+	// just return the diff path to the data
+	out := path.Join(a.rootPath(), "diff", id)
+	if len(ids) > 0 {
+		out = path.Join(a.rootPath(), "mnt", id)
+
+		if count == 0 {
+			if err := a.mount(id); err != nil {
+				return "", err
+			}
+		}
+	}
+
+	a.active[id] = count + 1
+
+	return out, nil
+}
+
+func (a *Driver) Put(id string) {
+	// Protect the a.active from concurrent access
+	a.Lock()
+	defer a.Unlock()
+
+	if count := a.active[id]; count > 1 {
+		a.active[id] = count - 1
+	} else {
+		ids, _ := getParentIds(a.rootPath(), id)
+		// We only mounted if there are any parents
+		if ids != nil && len(ids) > 0 {
+			a.unmount(id)
+		}
+		delete(a.active, id)
+	}
+}
+
+// Returns an archive of the contents for the id
+func (a *Driver) Diff(id string) (archive.Archive, error) {
+	return archive.TarFilter(path.Join(a.rootPath(), "diff", id), &archive.TarOptions{
+		Compression: archive.Uncompressed,
+	})
+}
+
+func (a *Driver) ApplyDiff(id string, diff archive.ArchiveReader) error {
+	return archive.Untar(diff, path.Join(a.rootPath(), "diff", id), nil)
+}
+
+// Returns the size of the contents for the id
+func (a *Driver) DiffSize(id string) (int64, error) {
+	return utils.TreeSize(path.Join(a.rootPath(), "diff", id))
+}
+
+func (a *Driver) Changes(id string) ([]archive.Change, error) {
+	layers, err := a.getParentLayerPaths(id)
+	if err != nil {
+		return nil, err
+	}
+	return archive.Changes(layers, path.Join(a.rootPath(), "diff", id))
+}
+
+func (a *Driver) getParentLayerPaths(id string) ([]string, error) {
+	parentIds, err := getParentIds(a.rootPath(), id)
+	if err != nil {
+		return nil, err
+	}
+	if len(parentIds) == 0 {
+		return nil, fmt.Errorf("Dir %s does not have any parent layers", id)
+	}
+	layers := make([]string, len(parentIds))
+
+	// Get the diff paths for all the parent ids
+	for i, p := range parentIds {
+		layers[i] = path.Join(a.rootPath(), "diff", p)
+	}
+	return layers, nil
+}
+
+func (a *Driver) mount(id string) error {
+	// If the id is mounted or we get an error return
+	if mounted, err := a.mounted(id); err != nil || mounted {
+		return err
+	}
+
+	var (
+		target = path.Join(a.rootPath(), "mnt", id)
+		rw     = path.Join(a.rootPath(), "diff", id)
+	)
+
+	layers, err := a.getParentLayerPaths(id)
+	if err != nil {
+		return err
+	}
+
+	if err := a.aufsMount(layers, rw, target); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (a *Driver) unmount(id string) error {
+	if mounted, err := a.mounted(id); err != nil || !mounted {
+		return err
+	}
+	target := path.Join(a.rootPath(), "mnt", id)
+	return Unmount(target)
+}
+
+func (a *Driver) mounted(id string) (bool, error) {
+	target := path.Join(a.rootPath(), "mnt", id)
+	return mountpk.Mounted(target)
+}
+
+// During cleanup aufs needs to unmount all mountpoints
+func (a *Driver) Cleanup() error {
+	ids, err := loadIds(path.Join(a.rootPath(), "layers"))
+	if err != nil {
+		return err
+	}
+	for _, id := range ids {
+		if err := a.unmount(id); err != nil {
+			utils.Errorf("Unmounting %s: %s", utils.TruncateID(id), err)
+		}
+	}
+	return nil
+}
+
+func (a *Driver) aufsMount(ro []string, rw, target string) (err error) {
+	defer func() {
+		if err != nil {
+			Unmount(target)
+		}
+	}()
+
+	if err = a.tryMount(ro, rw, target); err != nil {
+		if err = a.mountRw(rw, target); err != nil {
+			return
+		}
+
+		for _, layer := range ro {
+			branch := fmt.Sprintf("append:%s=ro+wh", layer)
+			if err = mount("none", target, "aufs", MsRemount, branch); err != nil {
+				return
+			}
+		}
+	}
+	return
+}
+
+// Try to mount using the aufs fast path, if this fails then
+// append ro layers.
+func (a *Driver) tryMount(ro []string, rw, target string) (err error) {
+	var (
+		rwBranch   = fmt.Sprintf("%s=rw", rw)
+		roBranches = fmt.Sprintf("%s=ro+wh:", strings.Join(ro, "=ro+wh:"))
+	)
+	return mount("none", target, "aufs", 0, fmt.Sprintf("br:%v:%v,xino=/dev/shm/aufs.xino", rwBranch, roBranches))
+}
+
+func (a *Driver) mountRw(rw, target string) error {
+	return mount("none", target, "aufs", 0, fmt.Sprintf("br:%s,xino=/dev/shm/aufs.xino", rw))
+}
+
+func rollbackMount(target string, err error) {
+	if err != nil {
+		Unmount(target)
+	}
+}