Add direct unpack support for overlay and aufs

Signed-off-by: Lantao Liu <lantaol@google.com>

archive/tar.go

@@ -19,9 +19,7 @@ package archive
 import (
 	"archive/tar"
 	"context"
-	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -91,11 +89,6 @@ const (
 	// archives.
 	whiteoutMetaPrefix = whiteoutPrefix + whiteoutPrefix
 
-	// whiteoutLinkDir is a directory AUFS uses for storing hardlink links to other
-	// layers. Normally these should not go into exported archives and all changed
-	// hardlinks should be copied to the top layer.
-	whiteoutLinkDir = whiteoutMetaPrefix + "plnk"
-
 	// whiteoutOpaqueDir file means directory has been made opaque - meaning
 	// readdir calls to this directory do not follow to lower layers.
 	whiteoutOpaqueDir = whiteoutMetaPrefix + ".opq"
@@ -130,10 +123,6 @@ func applyNaive(ctx context.Context, root string, tr *tar.Reader, options ApplyO
 		// Used for handling opaque directory markers which
 		// may occur out of order
 		unpackedPaths = make(map[string]struct{})
-
-		// Used for aufs plink directory
-		aufsTempdir   = ""
-		aufsHardlinks = make(map[string]*tar.Header)
 	)
 
 	// Iterate through the files in the archive.
@@ -201,40 +190,15 @@ func applyNaive(ctx context.Context, root string, tr *tar.Reader, options ApplyO
 			}
 		}
 
-		// Skip AUFS metadata dirs
-		if strings.HasPrefix(hdr.Name, whiteoutMetaPrefix) {
-			// Regular files inside /.wh..wh.plnk can be used as hardlink targets
-			// We don't want this directory, but we need the files in them so that
-			// such hardlinks can be resolved.
-			if strings.HasPrefix(hdr.Name, whiteoutLinkDir) && hdr.Typeflag == tar.TypeReg {
-				basename := filepath.Base(hdr.Name)
-				aufsHardlinks[basename] = hdr
-				if aufsTempdir == "" {
-					if aufsTempdir, err = ioutil.TempDir(os.Getenv("XDG_RUNTIME_DIR"), "dockerplnk"); err != nil {
-						return 0, err
-					}
-					defer os.RemoveAll(aufsTempdir)
-				}
-				p, err := fs.RootPath(aufsTempdir, basename)
-				if err != nil {
-					return 0, err
-				}
-				if err := createTarFile(ctx, p, root, hdr, tr); err != nil {
-					return 0, err
-				}
-			}
-
-			if hdr.Name != whiteoutOpaqueDir {
-				continue
-			}
-		}
-
-		if strings.HasPrefix(base, whiteoutPrefix) {
+		// Naive whiteout convert function which handles whiteout files by
+		// removing the target files.
+		convertWhiteout := func(hdr *tar.Header, path string) (bool, error) {
+			base := filepath.Base(path)
 			dir := filepath.Dir(path)
 			if base == whiteoutOpaqueDir {
 				_, err := os.Lstat(dir)
 				if err != nil {
-					return 0, err
+					return false, err
 				}
 				err = filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
 					if err != nil {
@@ -252,26 +216,29 @@ func applyNaive(ctx context.Context, root string, tr *tar.Reader, options ApplyO
 					}
 					return nil
 				})
-				if err != nil {
-					return 0, err
-				}
-				continue
+				return false, err
 			}
 
+			if strings.HasPrefix(base, whiteoutPrefix) {
 				originalBase := base[len(whiteoutPrefix):]
 				originalPath := filepath.Join(dir, originalBase)
 
-			// Ensure originalPath is under dir
-			if dir[len(dir)-1] != filepath.Separator {
-				dir += string(filepath.Separator)
-			}
-			if !strings.HasPrefix(originalPath, dir) {
-				return 0, errors.Wrapf(errInvalidArchive, "invalid whiteout name: %v", base)
+				return false, os.RemoveAll(originalPath)
 			}
 
-			if err := os.RemoveAll(originalPath); err != nil {
+			return true, nil
+		}
+		if options.ConvertWhiteout != nil {
+			convertWhiteout = options.ConvertWhiteout
+		}
+		if err := validateWhiteout(path); err != nil {
 			return 0, err
 		}
+		writeFile, err := convertWhiteout(hdr, path)
+		if err != nil {
+			return 0, errors.Wrapf(err, "failed to convert whiteout file %q", hdr.Name)
+		}
+		if !writeFile {
 			continue
 		}
 		// If path exits we almost always just want to remove and replace it.
@@ -289,26 +256,6 @@ func applyNaive(ctx context.Context, root string, tr *tar.Reader, options ApplyO
 		srcData := io.Reader(tr)
 		srcHdr := hdr
 
-		// Hard links into /.wh..wh.plnk don't work, as we don't extract that directory, so
-		// we manually retarget these into the temporary files we extracted them into
-		if hdr.Typeflag == tar.TypeLink && strings.HasPrefix(filepath.Clean(hdr.Linkname), whiteoutLinkDir) {
-			linkBasename := filepath.Base(hdr.Linkname)
-			srcHdr = aufsHardlinks[linkBasename]
-			if srcHdr == nil {
-				return 0, fmt.Errorf("invalid aufs hardlink")
-			}
-			p, err := fs.RootPath(aufsTempdir, linkBasename)
-			if err != nil {
-				return 0, err
-			}
-			tmpFile, err := os.Open(p)
-			if err != nil {
-				return 0, err
-			}
-			defer tmpFile.Close()
-			srcData = tmpFile
-		}
-
 		if err := createTarFile(ctx, path, root, srcHdr, srcData); err != nil {
 			return 0, err
 		}
@@ -684,3 +631,26 @@ func hardlinkRootPath(root, linkname string) (string, error) {
 	}
 	return targetPath, nil
 }
+
+func validateWhiteout(path string) error {
+	base := filepath.Base(path)
+	dir := filepath.Dir(path)
+
+	if base == whiteoutOpaqueDir {
+		return nil
+	}
+
+	if strings.HasPrefix(base, whiteoutPrefix) {
+		originalBase := base[len(whiteoutPrefix):]
+		originalPath := filepath.Join(dir, originalBase)
+
+		// Ensure originalPath is under dir
+		if dir[len(dir)-1] != filepath.Separator {
+			dir += string(filepath.Separator)
+		}
+		if !strings.HasPrefix(originalPath, dir) {
+			return errors.Wrapf(errInvalidArchive, "invalid whiteout name: %v", base)
+		}
+	}
+	return nil
+}

archive/tar_opts.go

@@ -24,6 +24,9 @@ type ApplyOpt func(options *ApplyOptions) error
 // Filter specific files from the archive
 type Filter func(*tar.Header) (bool, error)
 
+// ConvertWhiteout converts whiteout files from the archive
+type ConvertWhiteout func(*tar.Header, string) (bool, error)
+
 // all allows all files
 func all(_ *tar.Header) (bool, error) {
 	return true, nil
@@ -36,3 +39,11 @@ func WithFilter(f Filter) ApplyOpt {
 		return nil
 	}
 }
+
+// WithConvertWhiteout uses the convert function to convert the whiteout files.
+func WithConvertWhiteout(c ConvertWhiteout) ApplyOpt {
+	return func(options *ApplyOptions) error {
+		options.ConvertWhiteout = c
+		return nil
+	}
+}

archive/tar_opts_linux.go

@@ -0,0 +1,65 @@
+// +build linux
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package archive
+
+import (
+	"archive/tar"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/sys/unix"
+)
+
+// ApplyOptions provides additional options for an Apply operation
+type ApplyOptions struct {
+	Filter          Filter          // Filter tar headers
+	ConvertWhiteout ConvertWhiteout // Convert whiteout files
+}
+
+// AufsConvertWhiteout converts whiteout files for aufs.
+func AufsConvertWhiteout(_ *tar.Header, _ string) (bool, error) {
+	return true, nil
+}
+
+// OverlayConvertWhiteout converts whiteout files for overlay.
+func OverlayConvertWhiteout(hdr *tar.Header, path string) (bool, error) {
+	base := filepath.Base(path)
+	dir := filepath.Dir(path)
+
+	// if a directory is marked as opaque, we need to translate that to overlay
+	if base == whiteoutOpaqueDir {
+		// don't write the file itself
+		return false, unix.Setxattr(dir, "trusted.overlay.opaque", []byte{'y'}, 0)
+	}
+
+	// if a file was deleted and we are using overlay, we need to create a character device
+	if strings.HasPrefix(base, whiteoutPrefix) {
+		originalBase := base[len(whiteoutPrefix):]
+		originalPath := filepath.Join(dir, originalBase)
+
+		if err := unix.Mknod(originalPath, unix.S_IFCHR, 0); err != nil {
+			return false, err
+		}
+		// don't write the file itself
+		return false, os.Chown(originalPath, hdr.Uid, hdr.Gid)
+	}
+
+	return true, nil
+}

archive/tar_opts_other.go

@@ -1,4 +1,4 @@
-// +build !windows
+// +build !linux,!windows
 
 /*
    Copyright The containerd Authors.
@@ -21,4 +21,5 @@ package archive
 // ApplyOptions provides additional options for an Apply operation
 type ApplyOptions struct {
 	Filter          Filter          // Filter tar headers
+	ConvertWhiteout ConvertWhiteout // Convert whiteout files
 }

archive/tar_opts_windows.go

@@ -23,6 +23,7 @@ type ApplyOptions struct {
 	ParentLayerPaths        []string        // Parent layer paths used for Windows layer apply
 	IsWindowsContainerLayer bool            // True if the tar stream to be applied is a Windows Container Layer
 	Filter                  Filter          // Filter tar headers
+	ConvertWhiteout         ConvertWhiteout // Convert whiteout files
 }
 
 // WithParentLayers adds parent layers to the apply process this is required

diff/apply/apply.go

@@ -19,10 +19,8 @@ package apply
 import (
 	"context"
 	"io"
-	"io/ioutil"
 	"time"
 
-	"github.com/containerd/containerd/archive"
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/diff"
 	"github.com/containerd/containerd/log"
@@ -94,15 +92,8 @@ func (s *fsApplier) Apply(ctx context.Context, desc ocispec.Descriptor, mounts [
 	rc := &readCounter{
 		r: io.TeeReader(processor, digester.Hash()),
 	}
-	if err := mount.WithTempMount(ctx, mounts, func(root string) error {
-		if _, err := archive.Apply(ctx, root, rc); err != nil {
-			return err
-		}
 
-		// Read any trailing data
-		_, err := io.Copy(ioutil.Discard, rc)
-		return err
-	}); err != nil {
+	if err := apply(ctx, mounts, rc); err != nil {
 		return emptyDesc, err
 	}
 

diff/apply/apply_linux.go

@@ -0,0 +1,90 @@
+// +build linux
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package apply
+
+import (
+	"context"
+	"io"
+	"strings"
+
+	"github.com/containerd/containerd/archive"
+	"github.com/containerd/containerd/mount"
+	"github.com/pkg/errors"
+)
+
+func apply(ctx context.Context, mounts []mount.Mount, r io.Reader) error {
+	switch {
+	case len(mounts) == 1 && mounts[0].Type == "overlay":
+		path, err := getOverlayPath(mounts[0].Options)
+		if err != nil {
+			return err
+		}
+		_, err = archive.Apply(ctx, path, r,
+			archive.WithConvertWhiteout(archive.OverlayConvertWhiteout))
+		return err
+	case len(mounts) == 1 && mounts[0].Type == "aufs":
+		path, err := getAufsPath(mounts[0].Options)
+		if err != nil {
+			return err
+		}
+		_, err = archive.Apply(ctx, path, r,
+			archive.WithConvertWhiteout(archive.AufsConvertWhiteout))
+		return err
+	default:
+		return mount.WithTempMount(ctx, mounts, func(root string) error {
+			_, err := archive.Apply(ctx, root, r)
+			return err
+		})
+	}
+}
+
+func getOverlayPath(options []string) (string, error) {
+	const upperdirPrefix = "upperdir="
+	for _, o := range options {
+		if strings.HasPrefix(o, upperdirPrefix) {
+			return strings.TrimPrefix(o, upperdirPrefix), nil
+		}
+	}
+	return "", errors.New("upperdir not found")
+}
+
+func getAufsPath(options []string) (string, error) {
+	const (
+		sep       = ":"
+		brPrefix1 = "br:"
+		brPrefix2 = "br="
+		rwSuffix  = "=rw"
+	)
+	for _, o := range options {
+		if strings.HasPrefix(o, brPrefix1) {
+			o = strings.TrimPrefix(o, brPrefix1)
+		} else if strings.HasPrefix(o, brPrefix2) {
+			o = strings.TrimPrefix(o, brPrefix2)
+		} else {
+			continue
+		}
+		for _, b := range strings.Split(o, sep) {
+			if strings.HasSuffix(b, rwSuffix) {
+				return strings.TrimSuffix(b, rwSuffix), nil
+			}
+		}
+		break
+	}
+	return "", errors.New("rw branch not found")
+}

diff/apply/apply_linux_test.go

@@ -0,0 +1,79 @@
+// +build linux
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package apply
+
+import (
+	"testing"
+)
+
+func TestGetOverlayPath(t *testing.T) {
+	good := []string{"upperdir=/test/upper", "lowerdir=/test/lower", "workdir=/test/work"}
+	path, err := getOverlayPath(good)
+	if err != nil {
+		t.Fatalf("Get overlay path failed: %v", err)
+	}
+	if path != "/test/upper" {
+		t.Fatalf("Unexpected upperdir: %q", path)
+	}
+
+	bad := []string{"lowerdir=/test/lower"}
+	_, err = getOverlayPath(bad)
+	if err == nil {
+		t.Fatalf("An error is expected")
+	}
+}
+
+func TestGetAufsPath(t *testing.T) {
+	rwDir := "/test/rw"
+	for _, test := range []struct {
+		options   []string
+		expectErr bool
+	}{
+		{
+			options:   []string{"random:option", "br:" + rwDir + "=rw:/test/ro=ro+wh"},
+			expectErr: false,
+		},
+		{
+			options:   []string{"random:option", "br=" + rwDir + "=rw:/test/ro=ro+wh"},
+			expectErr: false,
+		},
+		{
+			options:   []string{"random:option"},
+			expectErr: true,
+		},
+		{
+			options:   []string{"br:/test/ro=ro+wh"},
+			expectErr: true,
+		},
+	} {
+		path, err := getAufsPath(test.options)
+		if test.expectErr {
+			if err == nil {
+				t.Fatalf("An error is expected")
+			}
+			continue
+		}
+		if err != nil {
+			t.Fatalf("Get aufs path failed: %v", err)
+		}
+		if path != rwDir {
+			t.Fatalf("Unexpected rw dir: %q", path)
+		}
+	}
+}

diff/apply/apply_other.go

@@ -0,0 +1,34 @@
+// +build !linux
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package apply
+
+import (
+	"context"
+	"io"
+
+	"github.com/containerd/containerd/archive"
+	"github.com/containerd/containerd/mount"
+)
+
+func apply(ctx context.Context, mounts []mount.Mount, r io.Reader) error {
+	return mount.WithTempMount(ctx, mounts, func(root string) error {
+		_, err := archive.Apply(ctx, root, r)
+		return err
+	})
+}