Merge pull request #483 from dmcgowan/snapshot-diff

Add fs package

fs/copy.go

@@ -0,0 +1,120 @@
+package fs
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	bufferPool = &sync.Pool{
+		New: func() interface{} {
+			return make([]byte, 32*1024)
+		},
+	}
+)
+
+// CopyDir copies the directory from src to dst.
+// Most efficient copy of files is attempted.
+func CopyDir(dst, src string) error {
+	inodes := map[uint64]string{}
+	return copyDirectory(dst, src, inodes)
+}
+
+func copyDirectory(dst, src string, inodes map[uint64]string) error {
+	stat, err := os.Stat(src)
+	if err != nil {
+		return errors.Wrapf(err, "failed to stat %s", src)
+	}
+	if !stat.IsDir() {
+		return errors.Errorf("source is not directory")
+	}
+
+	if st, err := os.Stat(dst); err != nil {
+		if err := os.Mkdir(dst, stat.Mode()); err != nil {
+			return errors.Wrapf(err, "failed to mkdir %s", dst)
+		}
+	} else if !st.IsDir() {
+		return errors.Errorf("cannot copy to non-directory: %s", dst)
+	} else {
+		if err := os.Chmod(dst, stat.Mode()); err != nil {
+			return errors.Wrapf(err, "failed to chmod on %s", dst)
+		}
+	}
+
+	fis, err := ioutil.ReadDir(src)
+	if err != nil {
+		return errors.Wrapf(err, "failed to read %s", src)
+	}
+
+	if err := copyFileInfo(stat, dst); err != nil {
+		return errors.Wrapf(err, "failed to copy file info for %s", dst)
+	}
+
+	for _, fi := range fis {
+		source := filepath.Join(src, fi.Name())
+		target := filepath.Join(dst, fi.Name())
+
+		switch {
+		case fi.IsDir():
+			if err := copyDirectory(target, source, inodes); err != nil {
+				return err
+			}
+			continue
+		case (fi.Mode() & os.ModeType) == 0:
+			link, err := GetLinkSource(target, fi, inodes)
+			if err != nil {
+				return errors.Wrap(err, "failed to get hardlink")
+			}
+			if link != "" {
+				if err := os.Link(link, target); err != nil {
+					return errors.Wrap(err, "failed to create hard link")
+				}
+			} else if err := copyFile(source, target); err != nil {
+				return errors.Wrap(err, "failed to copy files")
+			}
+		case (fi.Mode() & os.ModeSymlink) == os.ModeSymlink:
+			link, err := os.Readlink(source)
+			if err != nil {
+				return errors.Wrapf(err, "failed to read link: %s", source)
+			}
+			if err := os.Symlink(link, target); err != nil {
+				return errors.Wrapf(err, "failed to create symlink: %s", target)
+			}
+		case (fi.Mode() & os.ModeDevice) == os.ModeDevice:
+			if err := copyDevice(target, fi); err != nil {
+				return errors.Wrapf(err, "failed to create device")
+			}
+		default:
+			// TODO: Support pipes and sockets
+			return errors.Wrapf(err, "unsupported mode %s", fi.Mode())
+		}
+		if err := copyFileInfo(fi, target); err != nil {
+			return errors.Wrap(err, "failed to copy file info")
+		}
+
+		if err := copyXAttrs(target, source); err != nil {
+			return errors.Wrap(err, "failed to copy xattrs")
+		}
+	}
+
+	return nil
+}
+
+func copyFile(source, target string) error {
+	src, err := os.Open(source)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open source %s", err)
+	}
+	defer src.Close()
+	tgt, err := os.Create(target)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open target %s", err)
+	}
+	defer tgt.Close()
+
+	return copyFileContent(tgt, src)
+}

fs/copy_linux.go

@@ -0,0 +1,80 @@
+package fs
+
+import (
+	"io"
+	"os"
+	"syscall"
+
+	"github.com/pkg/errors"
+	"github.com/stevvooe/continuity/sysx"
+)
+
+func copyFileInfo(fi os.FileInfo, name string) error {
+	st := fi.Sys().(*syscall.Stat_t)
+	if err := os.Lchown(name, int(st.Uid), int(st.Gid)); err != nil {
+		return errors.Wrapf(err, "failed to chown %s", name)
+	}
+
+	if (fi.Mode() & os.ModeSymlink) != os.ModeSymlink {
+		if err := os.Chmod(name, fi.Mode()); err != nil {
+			return errors.Wrapf(err, "failed to chmod %s", name)
+		}
+	}
+
+	if err := syscall.UtimesNano(name, []syscall.Timespec{st.Atim, st.Mtim}); err != nil {
+		return errors.Wrapf(err, "failed to utime %s", name)
+	}
+
+	return nil
+}
+
+func copyFileContent(dst, src *os.File) error {
+	st, err := src.Stat()
+	if err != nil {
+		return errors.Wrap(err, "unable to stat source")
+	}
+
+	n, err := sysx.CopyFileRange(src.Fd(), nil, dst.Fd(), nil, int(st.Size()), 0)
+	if err != nil {
+		if err != syscall.ENOSYS && err != syscall.EXDEV {
+			return errors.Wrap(err, "copy file range failed")
+		}
+
+		buf := bufferPool.Get().([]byte)
+		_, err = io.CopyBuffer(dst, src, buf)
+		bufferPool.Put(buf)
+		return err
+	}
+
+	if int64(n) != st.Size() {
+		return errors.Wrapf(err, "short copy: %d of %d", int64(n), st.Size())
+	}
+
+	return nil
+}
+
+func copyXAttrs(dst, src string) error {
+	xattrKeys, err := sysx.LListxattr(src)
+	if err != nil {
+		return errors.Wrapf(err, "failed to list xattrs on %s", src)
+	}
+	for _, xattr := range xattrKeys {
+		data, err := sysx.LGetxattr(src, xattr)
+		if err != nil {
+			return errors.Wrapf(err, "failed to get xattr %q on %s", xattr, src)
+		}
+		if err := sysx.LSetxattr(dst, xattr, data, 0); err != nil {
+			return errors.Wrapf(err, "failed to set xattr %q on %s", xattr, dst)
+		}
+	}
+
+	return nil
+}
+
+func copyDevice(dst string, fi os.FileInfo) error {
+	st, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return errors.New("unsupported stat type")
+	}
+	return syscall.Mknod(dst, uint32(fi.Mode()), int(st.Rdev))
+}

fs/copy_test.go

@@ -0,0 +1,53 @@
+package fs
+
+import (
+	"io/ioutil"
+	"testing"
+
+	_ "crypto/sha256"
+
+	"github.com/docker/containerd/fs/fstest"
+	"github.com/pkg/errors"
+)
+
+// TODO: Create copy directory which requires privilege
+//  chown
+//  mknod
+//  setxattr fstest.SetXAttr("/home", "trusted.overlay.opaque", "y"),
+
+func TestCopyDirectory(t *testing.T) {
+	apply := fstest.Apply(
+		fstest.CreateDir("/etc/", 0755),
+		fstest.CreateFile("/etc/hosts", []byte("localhost 127.0.0.1"), 0644),
+		fstest.Link("/etc/hosts", "/etc/hosts.allow"),
+		fstest.CreateDir("/usr/local/lib", 0755),
+		fstest.CreateFile("/usr/local/lib/libnothing.so", []byte{0x00, 0x00}, 0755),
+		fstest.Symlink("libnothing.so", "/usr/local/lib/libnothing.so.2"),
+		fstest.CreateDir("/home", 0755),
+	)
+
+	if err := testCopy(apply); err != nil {
+		t.Fatalf("Copy test failed: %+v", err)
+	}
+}
+
+func testCopy(apply fstest.Applier) error {
+	t1, err := ioutil.TempDir("", "test-copy-src-")
+	if err != nil {
+		return errors.Wrap(err, "failed to create temporary directory")
+	}
+	t2, err := ioutil.TempDir("", "test-copy-dst-")
+	if err != nil {
+		return errors.Wrap(err, "failed to create temporary directory")
+	}
+
+	if err := apply.Apply(t1); err != nil {
+		return errors.Wrap(err, "failed to apply changes")
+	}
+
+	if err := CopyDir(t2, t1); err != nil {
+		return errors.Wrap(err, "failed to copy")
+	}
+
+	return fstest.CheckDirectoryEqual(t1, t2)
+}

fs/copy_windows.go

@@ -0,0 +1,33 @@
+package fs
+
+import (
+	"io"
+	"os"
+
+	"github.com/pkg/errors"
+)
+
+func copyFileInfo(fi os.FileInfo, name string) error {
+	if err := os.Chmod(name, fi.Mode()); err != nil {
+		return errors.Wrapf(err, "failed to chmod %s", name)
+	}
+
+	// TODO: copy windows specific metadata
+
+	return nil
+}
+
+func copyFileContent(dst, src *os.File) error {
+	buf := bufferPool.Get().([]byte)
+	_, err := io.CopyBuffer(dst, src, buf)
+	bufferPool.Put(buf)
+	return err
+}
+
+func copyXAttrs(dst, src string) error {
+	return nil
+}
+
+func copyDevice(dst string, fi os.FileInfo) error {
+	return errors.New("device copy not supported")
+}

fs/diff.go

@@ -0,0 +1,301 @@
+package fs
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/sync/errgroup"
+
+	"github.com/Sirupsen/logrus"
+)
+
+// ChangeKind is the type of modification that
+// a change is making.
+type ChangeKind int
+
+const (
+	// ChangeKindAdd represents an addition of
+	// a file
+	ChangeKindAdd = iota
+
+	// ChangeKindModify represents a change to
+	// an existing file
+	ChangeKindModify
+
+	// ChangeKindDelete represents a delete of
+	// a file
+	ChangeKindDelete
+)
+
+func (k ChangeKind) String() string {
+	switch k {
+	case ChangeKindAdd:
+		return "add"
+	case ChangeKindModify:
+		return "modify"
+	case ChangeKindDelete:
+		return "delete"
+	default:
+		return ""
+	}
+}
+
+// Change represents single change between a diff and its parent.
+type Change struct {
+	Kind ChangeKind
+	Path string
+}
+
+// ChangeFunc is the type of function called for each change
+// computed during a directory changes calculation.
+type ChangeFunc func(ChangeKind, string, os.FileInfo, error) error
+
+// Changes computes changes between two directories calling the
+// given change function for each computed change. The first
+// directory is intended to the base directory and second
+// directory the changed directory.
+//
+// The change callback is called by the order of path names and
+// should be appliable in that order.
+//  Due to this apply ordering, the following is true
+//  - Removed directory trees only create a single change for the root
+//    directory removed. Remaining changes are implied.
+//  - A directory which is modified to become a file will not have
+//    delete entries for sub-path items, their removal is implied
+//    by the removal of the parent directory.
+//
+// Opaque directories will not be treated specially and each file
+// removed from the base directory will show up as a removal.
+//
+// File content comparisons will be done on files which have timestamps
+// which may have been truncated. If either of the files being compared
+// has a zero value nanosecond value, each byte will be compared for
+// differences. If 2 files have the same seconds value but different
+// nanosecond values where one of those values is zero, the files will
+// be considered unchanged if the content is the same. This behavior
+// is to account for timestamp truncation during archiving.
+func Changes(ctx context.Context, a, b string, changeFn ChangeFunc) error {
+	if a == "" {
+		logrus.Debugf("Using single walk diff for %s", b)
+		return addDirChanges(ctx, changeFn, b)
+	} else if diffOptions := detectDirDiff(b, a); diffOptions != nil {
+		logrus.Debugf("Using single walk diff for %s from %s", diffOptions.diffDir, a)
+		return diffDirChanges(ctx, changeFn, a, diffOptions)
+	}
+
+	logrus.Debugf("Using double walk diff for %s from %s", b, a)
+	return doubleWalkDiff(ctx, changeFn, a, b)
+}
+
+func addDirChanges(ctx context.Context, changeFn ChangeFunc, root string) error {
+	return filepath.Walk(root, func(path string, f os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		// Rebase path
+		path, err = filepath.Rel(root, path)
+		if err != nil {
+			return err
+		}
+
+		path = filepath.Join(string(os.PathSeparator), path)
+
+		// Skip root
+		if path == string(os.PathSeparator) {
+			return nil
+		}
+
+		return changeFn(ChangeKindAdd, path, f, nil)
+	})
+}
+
+// diffDirOptions is used when the diff can be directly calculated from
+// a diff directory to its base, without walking both trees.
+type diffDirOptions struct {
+	diffDir      string
+	skipChange   func(string) (bool, error)
+	deleteChange func(string, string, os.FileInfo) (string, error)
+}
+
+// diffDirChanges walks the diff directory and compares changes against the base.
+func diffDirChanges(ctx context.Context, changeFn ChangeFunc, base string, o *diffDirOptions) error {
+	changedDirs := make(map[string]struct{})
+	return filepath.Walk(o.diffDir, func(path string, f os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		// Rebase path
+		path, err = filepath.Rel(o.diffDir, path)
+		if err != nil {
+			return err
+		}
+
+		path = filepath.Join(string(os.PathSeparator), path)
+
+		// Skip root
+		if path == string(os.PathSeparator) {
+			return nil
+		}
+
+		// TODO: handle opaqueness, start new double walker at this
+		// location to get deletes, and skip tree in single walker
+
+		if o.skipChange != nil {
+			if skip, err := o.skipChange(path); skip {
+				return err
+			}
+		}
+
+		var kind ChangeKind
+
+		deletedFile, err := o.deleteChange(o.diffDir, path, f)
+		if err != nil {
+			return err
+		}
+
+		// Find out what kind of modification happened
+		if deletedFile != "" {
+			path = deletedFile
+			kind = ChangeKindDelete
+			f = nil
+		} else {
+			// Otherwise, the file was added
+			kind = ChangeKindAdd
+
+			// ...Unless it already existed in a base, in which case, it's a modification
+			stat, err := os.Stat(filepath.Join(base, path))
+			if err != nil && !os.IsNotExist(err) {
+				return err
+			}
+			if err == nil {
+				// The file existed in the base, so that's a modification
+
+				// However, if it's a directory, maybe it wasn't actually modified.
+				// If you modify /foo/bar/baz, then /foo will be part of the changed files only because it's the parent of bar
+				if stat.IsDir() && f.IsDir() {
+					if f.Size() == stat.Size() && f.Mode() == stat.Mode() && sameFsTime(f.ModTime(), stat.ModTime()) {
+						// Both directories are the same, don't record the change
+						return nil
+					}
+				}
+				kind = ChangeKindModify
+			}
+		}
+
+		// If /foo/bar/file.txt is modified, then /foo/bar must be part of the changed files.
+		// This block is here to ensure the change is recorded even if the
+		// modify time, mode and size of the parent directory in the rw and ro layers are all equal.
+		// Check https://github.com/docker/docker/pull/13590 for details.
+		if f.IsDir() {
+			changedDirs[path] = struct{}{}
+		}
+		if kind == ChangeKindAdd || kind == ChangeKindDelete {
+			parent := filepath.Dir(path)
+			if _, ok := changedDirs[parent]; !ok && parent != "/" {
+				pi, err := os.Stat(filepath.Join(o.diffDir, parent))
+				if err := changeFn(ChangeKindModify, parent, pi, err); err != nil {
+					return err
+				}
+				changedDirs[parent] = struct{}{}
+			}
+		}
+
+		return changeFn(kind, path, f, nil)
+	})
+}
+
+// doubleWalkDiff walks both directories to create a diff
+func doubleWalkDiff(ctx context.Context, changeFn ChangeFunc, a, b string) (err error) {
+	g, ctx := errgroup.WithContext(ctx)
+
+	var (
+		c1 = make(chan *currentPath)
+		c2 = make(chan *currentPath)
+
+		f1, f2 *currentPath
+		rmdir  string
+	)
+	g.Go(func() error {
+		defer close(c1)
+		return pathWalk(ctx, a, c1)
+	})
+	g.Go(func() error {
+		defer close(c2)
+		return pathWalk(ctx, b, c2)
+	})
+	g.Go(func() error {
+		for c1 != nil || c2 != nil {
+			if f1 == nil && c1 != nil {
+				f1, err = nextPath(ctx, c1)
+				if err != nil {
+					return err
+				}
+				if f1 == nil {
+					c1 = nil
+				}
+			}
+
+			if f2 == nil && c2 != nil {
+				f2, err = nextPath(ctx, c2)
+				if err != nil {
+					return err
+				}
+				if f2 == nil {
+					c2 = nil
+				}
+			}
+			if f1 == nil && f2 == nil {
+				continue
+			}
+
+			var f os.FileInfo
+			k, p := pathChange(f1, f2)
+			switch k {
+			case ChangeKindAdd:
+				if rmdir != "" {
+					rmdir = ""
+				}
+				f = f2.f
+				f2 = nil
+			case ChangeKindDelete:
+				// Check if this file is already removed by being
+				// under of a removed directory
+				if rmdir != "" && strings.HasPrefix(f1.path, rmdir) {
+					f1 = nil
+					continue
+				} else if rmdir == "" && f1.f.IsDir() {
+					rmdir = f1.path + string(os.PathSeparator)
+				} else if rmdir != "" {
+					rmdir = ""
+				}
+				f1 = nil
+			case ChangeKindModify:
+				same, err := sameFile(f1, f2)
+				if err != nil {
+					return err
+				}
+				if f1.f.IsDir() && !f2.f.IsDir() {
+					rmdir = f1.path + string(os.PathSeparator)
+				} else if rmdir != "" {
+					rmdir = ""
+				}
+				f = f2.f
+				f1 = nil
+				f2 = nil
+				if same {
+					continue
+				}
+			}
+			if err := changeFn(k, p, f, nil); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+
+	return g.Wait()
+}

fs/diff_linux.go

@@ -0,0 +1,92 @@
+package fs
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/pkg/errors"
+	"github.com/stevvooe/continuity/sysx"
+)
+
+// whiteouts are files with a special meaning for the layered filesystem.
+// Docker uses AUFS whiteout files inside exported archives. In other
+// filesystems these files are generated/handled on tar creation/extraction.
+
+// whiteoutPrefix prefix means file is a whiteout. If this is followed by a
+// filename this means that file has been removed from the base layer.
+const whiteoutPrefix = ".wh."
+
+// whiteoutMetaPrefix prefix means whiteout has a special meaning and is not
+// for removing an actual file. Normally these files are excluded from exported
+// archives.
+const 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.
+const whiteoutLinkDir = whiteoutMetaPrefix + "plnk"
+
+// whiteoutOpaqueDir file means directory has been made opaque - meaning
+// readdir calls to this directory do not follow to lower layers.
+const whiteoutOpaqueDir = whiteoutMetaPrefix + ".opq"
+
+// detectDirDiff returns diff dir options if a directory could
+// be found in the mount info for upper which is the direct
+// diff with the provided lower directory
+func detectDirDiff(upper, lower string) *diffDirOptions {
+	// TODO: get mount options for upper
+	// TODO: detect AUFS
+	// TODO: detect overlay
+	return nil
+}
+
+func aufsMetadataSkip(path string) (skip bool, err error) {
+	skip, err = filepath.Match(string(os.PathSeparator)+whiteoutMetaPrefix+"*", path)
+	if err != nil {
+		skip = true
+	}
+	return
+}
+
+func aufsDeletedFile(root, path string, fi os.FileInfo) (string, error) {
+	f := filepath.Base(path)
+
+	// If there is a whiteout, then the file was removed
+	if strings.HasPrefix(f, whiteoutPrefix) {
+		originalFile := f[len(whiteoutPrefix):]
+		return filepath.Join(filepath.Dir(path), originalFile), nil
+	}
+
+	return "", nil
+}
+
+// compareSysStat returns whether the stats are equivalent,
+// whether the files are considered the same file, and
+// an error
+func compareSysStat(s1, s2 interface{}) (bool, error) {
+	ls1, ok := s1.(*syscall.Stat_t)
+	if !ok {
+		return false, nil
+	}
+	ls2, ok := s2.(*syscall.Stat_t)
+	if !ok {
+		return false, nil
+	}
+
+	return ls1.Mode == ls2.Mode && ls1.Uid == ls2.Uid && ls1.Gid == ls2.Gid && ls1.Rdev == ls2.Rdev, nil
+}
+
+func compareCapabilities(p1, p2 string) (bool, error) {
+	c1, err := sysx.LGetxattr(p1, "security.capability")
+	if err != nil && err != syscall.ENODATA {
+		return false, errors.Wrapf(err, "failed to get xattr for %s", p1)
+	}
+	c2, err := sysx.LGetxattr(p2, "security.capability")
+	if err != nil && err != syscall.ENODATA {
+		return false, errors.Wrapf(err, "failed to get xattr for %s", p2)
+	}
+	return bytes.Equal(c1, c2), nil
+}

fs/diff_test.go

@@ -0,0 +1,316 @@
+package fs
+
+import (
+	"context"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/docker/containerd/fs/fstest"
+	"github.com/pkg/errors"
+)
+
+// TODO: Additional tests
+// - capability test (requires privilege)
+// - chown test (requires privilege)
+// - symlink test
+// - hardlink test
+
+func TestSimpleDiff(t *testing.T) {
+	l1 := fstest.Apply(
+		fstest.CreateDir("/etc", 0755),
+		fstest.CreateFile("/etc/hosts", []byte("mydomain 10.0.0.1"), 0644),
+		fstest.CreateFile("/etc/profile", []byte("PATH=/usr/bin"), 0644),
+		fstest.CreateFile("/etc/unchanged", []byte("PATH=/usr/bin"), 0644),
+		fstest.CreateFile("/etc/unexpected", []byte("#!/bin/sh"), 0644),
+	)
+	l2 := fstest.Apply(
+		fstest.CreateFile("/etc/hosts", []byte("mydomain 10.0.0.120"), 0644),
+		fstest.CreateFile("/etc/profile", []byte("PATH=/usr/bin"), 0666),
+		fstest.CreateDir("/root", 0700),
+		fstest.CreateFile("/root/.bashrc", []byte("PATH=/usr/sbin:/usr/bin"), 0644),
+		fstest.RemoveFile("/etc/unexpected"),
+	)
+	diff := []testChange{
+		Modify("/etc/hosts"),
+		Modify("/etc/profile"),
+		Delete("/etc/unexpected"),
+		Add("/root"),
+		Add("/root/.bashrc"),
+	}
+
+	if err := testDiffWithBase(l1, l2, diff); err != nil {
+		t.Fatalf("Failed diff with base: %+v", err)
+	}
+}
+
+func TestDirectoryReplace(t *testing.T) {
+	l1 := fstest.Apply(
+		fstest.CreateDir("/dir1", 0755),
+		fstest.CreateFile("/dir1/f1", []byte("#####"), 0644),
+		fstest.CreateDir("/dir1/f2", 0755),
+		fstest.CreateFile("/dir1/f2/f3", []byte("#!/bin/sh"), 0644),
+	)
+	l2 := fstest.Apply(
+		fstest.CreateFile("/dir1/f11", []byte("#New file here"), 0644),
+		fstest.RemoveFile("/dir1/f2"),
+		fstest.CreateFile("/dir1/f2", []byte("Now file"), 0666),
+	)
+	diff := []testChange{
+		Add("/dir1/f11"),
+		Modify("/dir1/f2"),
+	}
+
+	if err := testDiffWithBase(l1, l2, diff); err != nil {
+		t.Fatalf("Failed diff with base: %+v", err)
+	}
+}
+
+func TestRemoveDirectoryTree(t *testing.T) {
+	l1 := fstest.Apply(
+		fstest.CreateDir("/dir1/dir2/dir3", 0755),
+		fstest.CreateFile("/dir1/f1", []byte("f1"), 0644),
+		fstest.CreateFile("/dir1/dir2/f2", []byte("f2"), 0644),
+	)
+	l2 := fstest.Apply(
+		fstest.RemoveFile("/dir1"),
+	)
+	diff := []testChange{
+		Delete("/dir1"),
+	}
+
+	if err := testDiffWithBase(l1, l2, diff); err != nil {
+		t.Fatalf("Failed diff with base: %+v", err)
+	}
+}
+
+func TestFileReplace(t *testing.T) {
+	l1 := fstest.Apply(
+		fstest.CreateFile("/dir1", []byte("a file, not a directory"), 0644),
+	)
+	l2 := fstest.Apply(
+		fstest.RemoveFile("/dir1"),
+		fstest.CreateDir("/dir1/dir2", 0755),
+		fstest.CreateFile("/dir1/dir2/f1", []byte("also a file"), 0644),
+	)
+	diff := []testChange{
+		Modify("/dir1"),
+		Add("/dir1/dir2"),
+		Add("/dir1/dir2/f1"),
+	}
+
+	if err := testDiffWithBase(l1, l2, diff); err != nil {
+		t.Fatalf("Failed diff with base: %+v", err)
+	}
+}
+
+func TestUpdateWithSameTime(t *testing.T) {
+	tt := time.Now().Truncate(time.Second)
+	t1 := tt.Add(5 * time.Nanosecond)
+	t2 := tt.Add(6 * time.Nanosecond)
+	l1 := fstest.Apply(
+		fstest.CreateFile("/file-modified-time", []byte("1"), 0644),
+		fstest.Chtime("/file-modified-time", t1),
+		fstest.CreateFile("/file-no-change", []byte("1"), 0644),
+		fstest.Chtime("/file-no-change", t1),
+		fstest.CreateFile("/file-same-time", []byte("1"), 0644),
+		fstest.Chtime("/file-same-time", t1),
+		fstest.CreateFile("/file-truncated-time-1", []byte("1"), 0644),
+		fstest.Chtime("/file-truncated-time-1", t1),
+		fstest.CreateFile("/file-truncated-time-2", []byte("1"), 0644),
+		fstest.Chtime("/file-truncated-time-2", tt),
+	)
+	l2 := fstest.Apply(
+		fstest.CreateFile("/file-modified-time", []byte("2"), 0644),
+		fstest.Chtime("/file-modified-time", t2),
+		fstest.CreateFile("/file-no-change", []byte("1"), 0644),
+		fstest.Chtime("/file-no-change", tt), // use truncated time, should be regarded as no change
+		fstest.CreateFile("/file-same-time", []byte("2"), 0644),
+		fstest.Chtime("/file-same-time", t1),
+		fstest.CreateFile("/file-truncated-time-1", []byte("2"), 0644),
+		fstest.Chtime("/file-truncated-time-1", tt),
+		fstest.CreateFile("/file-truncated-time-2", []byte("2"), 0644),
+		fstest.Chtime("/file-truncated-time-2", tt),
+	)
+	diff := []testChange{
+		// "/file-same-time" excluded because matching non-zero nanosecond values
+		Modify("/file-modified-time"),
+		Modify("/file-truncated-time-1"),
+		Modify("/file-truncated-time-2"),
+	}
+
+	if err := testDiffWithBase(l1, l2, diff); err != nil {
+		t.Fatalf("Failed diff with base: %+v", err)
+	}
+}
+
+func testDiffWithBase(base, diff fstest.Applier, expected []testChange) error {
+	t1, err := ioutil.TempDir("", "diff-with-base-lower-")
+	if err != nil {
+		return errors.Wrap(err, "failed to create temp dir")
+	}
+	defer os.RemoveAll(t1)
+	t2, err := ioutil.TempDir("", "diff-with-base-upper-")
+	if err != nil {
+		return errors.Wrap(err, "failed to create temp dir")
+	}
+	defer os.RemoveAll(t2)
+
+	if err := base.Apply(t1); err != nil {
+		return errors.Wrap(err, "failed to apply base filesytem")
+	}
+
+	if err := CopyDir(t2, t1); err != nil {
+		return errors.Wrap(err, "failed to copy base directory")
+	}
+
+	if err := diff.Apply(t2); err != nil {
+		return errors.Wrap(err, "failed to apply diff filesystem")
+	}
+
+	changes, err := collectChanges(t1, t2)
+	if err != nil {
+		return errors.Wrap(err, "failed to collect changes")
+	}
+
+	return checkChanges(t2, changes, expected)
+}
+
+func TestBaseDirectoryChanges(t *testing.T) {
+	apply := fstest.Apply(
+		fstest.CreateDir("/etc", 0755),
+		fstest.CreateFile("/etc/hosts", []byte("mydomain 10.0.0.1"), 0644),
+		fstest.CreateFile("/etc/profile", []byte("PATH=/usr/bin"), 0644),
+		fstest.CreateDir("/root", 0700),
+		fstest.CreateFile("/root/.bashrc", []byte("PATH=/usr/sbin:/usr/bin"), 0644),
+	)
+	changes := []testChange{
+		Add("/etc"),
+		Add("/etc/hosts"),
+		Add("/etc/profile"),
+		Add("/root"),
+		Add("/root/.bashrc"),
+	}
+
+	if err := testDiffWithoutBase(apply, changes); err != nil {
+		t.Fatalf("Failed diff without base: %+v", err)
+	}
+}
+
+func testDiffWithoutBase(apply fstest.Applier, expected []testChange) error {
+	tmp, err := ioutil.TempDir("", "diff-without-base-")
+	if err != nil {
+		return errors.Wrap(err, "failed to create temp dir")
+	}
+	defer os.RemoveAll(tmp)
+
+	if err := apply.Apply(tmp); err != nil {
+		return errors.Wrap(err, "failed to apply filesytem changes")
+	}
+
+	changes, err := collectChanges("", tmp)
+	if err != nil {
+		return errors.Wrap(err, "failed to collect changes")
+	}
+
+	return checkChanges(tmp, changes, expected)
+}
+
+func checkChanges(root string, changes, expected []testChange) error {
+	if len(changes) != len(expected) {
+		return errors.Errorf("Unexpected number of changes:\n%s", diffString(changes, expected))
+	}
+	for i := range changes {
+		if changes[i].Path != expected[i].Path || changes[i].Kind != expected[i].Kind {
+			return errors.Errorf("Unexpected change at %d:\n%s", i, diffString(changes, expected))
+		}
+		if changes[i].Kind != ChangeKindDelete {
+			filename := filepath.Join(root, changes[i].Path)
+			efi, err := os.Stat(filename)
+			if err != nil {
+				return errors.Wrapf(err, "failed to stat %q", filename)
+			}
+			afi := changes[i].FileInfo
+			if afi.Size() != efi.Size() {
+				return errors.Errorf("Unexpected change size %d, %q has size %d", afi.Size(), filename, efi.Size())
+			}
+			if afi.Mode() != efi.Mode() {
+				return errors.Errorf("Unexpected change mode %s, %q has mode %s", afi.Mode(), filename, efi.Mode())
+			}
+			if afi.ModTime() != efi.ModTime() {
+				return errors.Errorf("Unexpected change modtime %s, %q has modtime %s", afi.ModTime(), filename, efi.ModTime())
+			}
+			if expected := filepath.Join(root, changes[i].Path); changes[i].Source != expected {
+				return errors.Errorf("Unexpected source path %s, expected %s", changes[i].Source, expected)
+			}
+		}
+	}
+
+	return nil
+}
+
+type testChange struct {
+	Kind     ChangeKind
+	Path     string
+	FileInfo os.FileInfo
+	Source   string
+}
+
+func collectChanges(a, b string) ([]testChange, error) {
+	changes := []testChange{}
+	err := Changes(context.Background(), a, b, func(k ChangeKind, p string, f os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		changes = append(changes, testChange{
+			Kind:     k,
+			Path:     p,
+			FileInfo: f,
+			Source:   filepath.Join(b, p),
+		})
+		return nil
+	})
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to compute changes")
+	}
+
+	return changes, nil
+}
+
+func diffString(c1, c2 []testChange) string {
+	return fmt.Sprintf("got(%d):\n%s\nexpected(%d):\n%s", len(c1), changesString(c1), len(c2), changesString(c2))
+
+}
+
+func changesString(c []testChange) string {
+	strs := make([]string, len(c))
+	for i := range c {
+		strs[i] = fmt.Sprintf("\t%s\t%s", c[i].Kind, c[i].Path)
+	}
+	return strings.Join(strs, "\n")
+}
+
+func Add(p string) testChange {
+	return testChange{
+		Kind: ChangeKindAdd,
+		Path: p,
+	}
+}
+
+func Delete(p string) testChange {
+	return testChange{
+		Kind: ChangeKindDelete,
+		Path: p,
+	}
+}
+
+func Modify(p string) testChange {
+	return testChange{
+		Kind: ChangeKindModify,
+		Path: p,
+	}
+}

fs/diff_windows.go

@@ -0,0 +1,15 @@
+package fs
+
+func detectDirDiff(upper, lower string) *diffDirOptions {
+	return nil
+}
+
+func compareSysStat(s1, s2 interface{}) (bool, error) {
+	// TODO: Use windows specific sys type
+	return false, nil
+}
+
+func compareCapabilities(p1, p2 string) (bool, error) {
+	// TODO: Use windows equivalent
+	return true, nil
+}

fs/fstest/compare.go

@@ -0,0 +1,37 @@
+package fstest
+
+import (
+	"github.com/pkg/errors"
+	"github.com/stevvooe/continuity"
+)
+
+// CheckDirectoryEqual compares two directory paths to make sure that
+// the content of the directories is the same.
+func CheckDirectoryEqual(d1, d2 string) error {
+	c1, err := continuity.NewContext(d1)
+	if err != nil {
+		return errors.Wrap(err, "failed to build context")
+	}
+
+	c2, err := continuity.NewContext(d2)
+	if err != nil {
+		return errors.Wrap(err, "failed to build context")
+	}
+
+	m1, err := continuity.BuildManifest(c1)
+	if err != nil {
+		return errors.Wrap(err, "failed to build manifest")
+	}
+
+	m2, err := continuity.BuildManifest(c2)
+	if err != nil {
+		return errors.Wrap(err, "failed to build manifest")
+	}
+
+	diff := diffResourceList(m1.Resources, m2.Resources)
+	if diff.HasDiff() {
+		return errors.Errorf("directory diff between %s and %s\n%s", d1, d2, diff.String())
+	}
+
+	return nil
+}

fs/fstest/continuity_util.go

@@ -0,0 +1,189 @@
+package fstest
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/stevvooe/continuity"
+)
+
+type resourceUpdate struct {
+	Original continuity.Resource
+	Updated  continuity.Resource
+}
+
+func (u resourceUpdate) String() string {
+	return fmt.Sprintf("%s(mode: %o, uid: %s, gid: %s) -> %s(mode: %o, uid: %s, gid: %s)",
+		u.Original.Path(), u.Original.Mode(), u.Original.UID(), u.Original.GID(),
+		u.Updated.Path(), u.Updated.Mode(), u.Updated.UID(), u.Updated.GID(),
+	)
+}
+
+type resourceListDifference struct {
+	Additions []continuity.Resource
+	Deletions []continuity.Resource
+	Updates   []resourceUpdate
+}
+
+func (l resourceListDifference) HasDiff() bool {
+	return len(l.Additions) > 0 || len(l.Deletions) > 0 || len(l.Updates) > 0
+}
+
+func (l resourceListDifference) String() string {
+	buf := bytes.NewBuffer(nil)
+	for _, add := range l.Additions {
+		fmt.Fprintf(buf, "+ %s\n", add.Path())
+	}
+	for _, del := range l.Deletions {
+		fmt.Fprintf(buf, "- %s\n", del.Path())
+	}
+	for _, upt := range l.Updates {
+		fmt.Fprintf(buf, "~ %s\n", upt.String())
+	}
+	return string(buf.Bytes())
+}
+
+// diffManifest compares two resource lists and returns the list
+// of adds updates and deletes, resource lists are not reordered
+// before doing difference.
+func diffResourceList(r1, r2 []continuity.Resource) resourceListDifference {
+	i1 := 0
+	i2 := 0
+	var d resourceListDifference
+
+	for i1 < len(r1) && i2 < len(r2) {
+		p1 := r1[i1].Path()
+		p2 := r2[i2].Path()
+		switch {
+		case p1 < p2:
+			d.Deletions = append(d.Deletions, r1[i1])
+			i1++
+		case p1 == p2:
+			if !compareResource(r1[i1], r2[i2]) {
+				d.Updates = append(d.Updates, resourceUpdate{
+					Original: r1[i1],
+					Updated:  r2[i2],
+				})
+			}
+			i1++
+			i2++
+		case p1 > p2:
+			d.Additions = append(d.Additions, r2[i2])
+			i2++
+		}
+	}
+
+	for i1 < len(r1) {
+		d.Deletions = append(d.Deletions, r1[i1])
+		i1++
+
+	}
+	for i2 < len(r2) {
+		d.Additions = append(d.Additions, r2[i2])
+		i2++
+	}
+
+	return d
+}
+
+func compareResource(r1, r2 continuity.Resource) bool {
+	if r1.Path() != r2.Path() {
+		return false
+	}
+	if r1.Mode() != r2.Mode() {
+		return false
+	}
+	if r1.UID() != r2.UID() {
+		return false
+	}
+	if r1.GID() != r2.GID() {
+		return false
+	}
+
+	// TODO(dmcgowan): Check if is XAttrer
+
+	return compareResourceTypes(r1, r2)
+
+}
+
+func compareResourceTypes(r1, r2 continuity.Resource) bool {
+	switch t1 := r1.(type) {
+	case continuity.RegularFile:
+		t2, ok := r2.(continuity.RegularFile)
+		if !ok {
+			return false
+		}
+		return compareRegularFile(t1, t2)
+	case continuity.Directory:
+		t2, ok := r2.(continuity.Directory)
+		if !ok {
+			return false
+		}
+		return compareDirectory(t1, t2)
+	case continuity.SymLink:
+		t2, ok := r2.(continuity.SymLink)
+		if !ok {
+			return false
+		}
+		return compareSymLink(t1, t2)
+	case continuity.NamedPipe:
+		t2, ok := r2.(continuity.NamedPipe)
+		if !ok {
+			return false
+		}
+		return compareNamedPipe(t1, t2)
+	case continuity.Device:
+		t2, ok := r2.(continuity.Device)
+		if !ok {
+			return false
+		}
+		return compareDevice(t1, t2)
+	default:
+		// TODO(dmcgowan): Should this panic?
+		return r1 == r2
+	}
+}
+
+func compareRegularFile(r1, r2 continuity.RegularFile) bool {
+	if r1.Size() != r2.Size() {
+		return false
+	}
+	p1 := r1.Paths()
+	p2 := r2.Paths()
+	if len(p1) != len(p2) {
+		return false
+	}
+	for i := range p1 {
+		if p1[i] != p2[i] {
+			return false
+		}
+	}
+	d1 := r1.Digests()
+	d2 := r2.Digests()
+	if len(d1) != len(d2) {
+		return false
+	}
+	for i := range d1 {
+		if d1[i] != d2[i] {
+			return false
+		}
+	}
+
+	return true
+}
+
+func compareSymLink(r1, r2 continuity.SymLink) bool {
+	return r1.Target() == r2.Target()
+}
+
+func compareDirectory(r1, r2 continuity.Directory) bool {
+	return true
+}
+
+func compareNamedPipe(r1, r2 continuity.NamedPipe) bool {
+	return true
+}
+
+func compareDevice(r1, r2 continuity.Device) bool {
+	return r1.Major() == r2.Major() && r1.Minor() == r2.Minor()
+}

fs/fstest/file.go

@@ -0,0 +1,117 @@
+package fstest
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/stevvooe/continuity/sysx"
+)
+
+// Applier applies single file changes
+type Applier interface {
+	Apply(root string) error
+}
+
+type applyFn func(root string) error
+
+func (a applyFn) Apply(root string) error {
+	return a(root)
+}
+
+// CreateFile returns a file applier which creates a file as the
+// provided name with the given content and permission.
+func CreateFile(name string, content []byte, perm os.FileMode) Applier {
+	return applyFn(func(root string) error {
+		fullPath := filepath.Join(root, name)
+		if err := ioutil.WriteFile(fullPath, content, perm); err != nil {
+			return err
+		}
+
+		if err := os.Chmod(fullPath, perm); err != nil {
+			return err
+		}
+
+		return nil
+	})
+}
+
+// RemoveFile returns a file applier which removes the provided file name
+func RemoveFile(name string) Applier {
+	return applyFn(func(root string) error {
+		return os.RemoveAll(filepath.Join(root, name))
+	})
+}
+
+// CreateDir returns a file applier to create the directory with
+// the provided name and permission
+func CreateDir(name string, perm os.FileMode) Applier {
+	return applyFn(func(root string) error {
+		fullPath := filepath.Join(root, name)
+		if err := os.MkdirAll(fullPath, perm); err != nil {
+			return err
+		}
+		return nil
+	})
+}
+
+// Rename returns a file applier which renames a file
+func Rename(old, new string) Applier {
+	return applyFn(func(root string) error {
+		return os.Rename(filepath.Join(root, old), filepath.Join(root, new))
+	})
+}
+
+// Chown returns a file applier which changes the ownership of a file
+func Chown(name string, uid, gid int) Applier {
+	return applyFn(func(root string) error {
+		return os.Chown(filepath.Join(root, name), uid, gid)
+	})
+}
+
+// Chtime changes access and mod time of file
+func Chtime(name string, t time.Time) Applier {
+	return applyFn(func(root string) error {
+		return os.Chtimes(filepath.Join(root, name), t, t)
+	})
+}
+
+// Symlink returns a file applier which creates a symbolic link
+func Symlink(oldname, newname string) Applier {
+	return applyFn(func(root string) error {
+		return os.Symlink(oldname, filepath.Join(root, newname))
+	})
+}
+
+// Link returns a file applier which creates a hard link
+func Link(oldname, newname string) Applier {
+	return applyFn(func(root string) error {
+		return os.Link(filepath.Join(root, oldname), filepath.Join(root, newname))
+	})
+}
+
+func SetXAttr(name, key, value string) Applier {
+	return applyFn(func(root string) error {
+		return sysx.LSetxattr(name, key, []byte(value), 0)
+	})
+}
+
+// TODO: Make platform specific, windows applier is always no-op
+//func Mknod(name string, mode int32, dev int) Applier {
+//	return func(root string) error {
+//		return return syscall.Mknod(path, mode, dev)
+//	}
+//}
+
+// Apply returns a new applier from the given appliers
+func Apply(appliers ...Applier) Applier {
+	return applyFn(func(root string) error {
+		for _, a := range appliers {
+			if err := a.Apply(root); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+}

fs/hardlink.go

@@ -0,0 +1,12 @@
+package fs
+
+import "os"
+
+// GetLinkSource returns a path for the given name and
+// file info to its link source in the provided inode
+// map. If the given file name is not in the map and
+// has other links, it is added to the inode map
+// to be a source for other link locations.
+func GetLinkSource(name string, fi os.FileInfo, inodes map[uint64]string) (string, error) {
+	return getHardLink(name, fi, inodes)
+}

fs/hardlink_unix.go

@@ -0,0 +1,33 @@
+// +build !windows
+
+package fs
+
+import (
+	"errors"
+	"os"
+	"syscall"
+)
+
+func getHardLink(name string, fi os.FileInfo, inodes map[uint64]string) (string, error) {
+	if fi.IsDir() {
+		return "", nil
+	}
+
+	s, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return "", errors.New("unsupported stat type")
+	}
+
+	// If inode is not hardlinked, no reason to lookup or save inode
+	if s.Nlink == 1 {
+		return "", nil
+	}
+
+	inode := uint64(s.Ino)
+
+	path, ok := inodes[inode]
+	if !ok {
+		inodes[inode] = name
+	}
+	return path, nil
+}

fs/hardlink_windows.go

@@ -0,0 +1,7 @@
+package fs
+
+import "os"
+
+func getHardLink(string, os.FileInfo, map[uint64]string) (string, error) {
+	return "", nil
+}

fs/path.go

@@ -0,0 +1,162 @@
+package fs
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+type currentPath struct {
+	path     string
+	f        os.FileInfo
+	fullPath string
+}
+
+func pathChange(lower, upper *currentPath) (ChangeKind, string) {
+	if lower == nil {
+		if upper == nil {
+			panic("cannot compare nil paths")
+		}
+		return ChangeKindAdd, upper.path
+	}
+	if upper == nil {
+		return ChangeKindDelete, lower.path
+	}
+	// TODO: compare by directory
+
+	switch i := strings.Compare(lower.path, upper.path); {
+	case i < 0:
+		// File in lower that is not in upper
+		return ChangeKindDelete, lower.path
+	case i > 0:
+		// File in upper that is not in lower
+		return ChangeKindAdd, upper.path
+	default:
+		return ChangeKindModify, upper.path
+	}
+}
+
+func sameFile(f1, f2 *currentPath) (bool, error) {
+	if os.SameFile(f1.f, f2.f) {
+		return true, nil
+	}
+
+	equalStat, err := compareSysStat(f1.f.Sys(), f2.f.Sys())
+	if err != nil || !equalStat {
+		return equalStat, err
+	}
+
+	if eq, err := compareCapabilities(f1.fullPath, f2.fullPath); err != nil || !eq {
+		return eq, err
+	}
+
+	// If not a directory also check size, modtime, and content
+	if !f1.f.IsDir() {
+		if f1.f.Size() != f2.f.Size() {
+			return false, nil
+		}
+		t1 := f1.f.ModTime()
+		t2 := f2.f.ModTime()
+
+		if t1.Unix() != t2.Unix() {
+			return false, nil
+		}
+
+		// If the timestamp may have been truncated in one of the
+		// files, check content of file to determine difference
+		if t1.Nanosecond() == 0 || t2.Nanosecond() == 0 {
+			if f1.f.Size() > 0 {
+				eq, err := compareFileContent(f1.fullPath, f2.fullPath)
+				if err != nil || !eq {
+					return eq, err
+				}
+			}
+		} else if t1.Nanosecond() != t2.Nanosecond() {
+			return false, nil
+		}
+	}
+
+	return true, nil
+}
+
+const compareChuckSize = 32 * 1024
+
+// compareFileContent compares the content of 2 same sized files
+// by comparing each byte.
+func compareFileContent(p1, p2 string) (bool, error) {
+	f1, err := os.Open(p1)
+	if err != nil {
+		return false, err
+	}
+	defer f1.Close()
+	f2, err := os.Open(p2)
+	if err != nil {
+		return false, err
+	}
+	defer f2.Close()
+
+	b1 := make([]byte, compareChuckSize)
+	b2 := make([]byte, compareChuckSize)
+	for {
+		n1, err1 := f1.Read(b1)
+		if err1 != nil && err1 != io.EOF {
+			return false, err1
+		}
+		n2, err2 := f2.Read(b2)
+		if err2 != nil && err2 != io.EOF {
+			return false, err2
+		}
+		if n1 != n2 || !bytes.Equal(b1[:n1], b2[:n2]) {
+			return false, nil
+		}
+		if err1 == io.EOF && err2 == io.EOF {
+			return true, nil
+		}
+	}
+}
+
+func pathWalk(ctx context.Context, root string, pathC chan<- *currentPath) error {
+	return filepath.Walk(root, func(path string, f os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		// Rebase path
+		path, err = filepath.Rel(root, path)
+		if err != nil {
+			return err
+		}
+
+		path = filepath.Join(string(os.PathSeparator), path)
+
+		// Skip root
+		if path == string(os.PathSeparator) {
+			return nil
+		}
+
+		p := &currentPath{
+			path:     path,
+			f:        f,
+			fullPath: filepath.Join(root, path),
+		}
+
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case pathC <- p:
+			return nil
+		}
+	})
+}
+
+func nextPath(ctx context.Context, pathC <-chan *currentPath) (*currentPath, error) {
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	case p := <-pathC:
+		return p, nil
+	}
+}

fs/time.go

@@ -0,0 +1,13 @@
+package fs
+
+import "time"
+
+// Gnu tar and the go tar writer don't have sub-second mtime
+// precision, which is problematic when we apply changes via tar
+// files, we handle this by comparing for exact times, *or* same
+// second count and either a or b having exactly 0 nanoseconds
+func sameFsTime(a, b time.Time) bool {
+	return a == b ||
+		(a.Unix() == b.Unix() &&
+			(a.Nanosecond() == 0 || b.Nanosecond() == 0))
+}

snapshot/naive/naive.go

@@ -7,7 +7,7 @@ import (
 	"path/filepath"
 
 	"github.com/docker/containerd"
-	"github.com/docker/docker/pkg/archive"
+	"github.com/docker/containerd/fs"
 	"github.com/pkg/errors"
 )
 
@@ -66,7 +66,7 @@ func (n *Naive) Prepare(dst, parent string) ([]containerd.Mount, error) {
 		}
 
 		// Now, we copy the parent filesystem, just a directory, into dst.
-		if err := archive.CopyWithTar(filepath.Join(parent, "data"), dst); err != nil { // note: src, dst args, ick!
+		if err := fs.CopyDir(dst, filepath.Join(parent, "data")); err != nil {
 			return nil, errors.Wrap(err, "copying of parent failed")
 		}
 	}
@@ -88,7 +88,7 @@ func (n *Naive) Commit(diff, dst string) error {
 
 	// Move the data into our metadata directory, we could probably save disk
 	// space if we just saved the diff, but let's get something working.
-	if err := archive.CopyWithTar(dst, filepath.Join(active.metadata, "data")); err != nil { // note: src, dst args, ick!
+	if err := fs.CopyDir(filepath.Join(active.metadata, "data"), dst); err != nil {
 		return errors.Wrap(err, "copying of parent failed")
 	}
 

vendor.conf

@@ -68,3 +68,7 @@ github.com/opencontainers/go-digest 21dfd564fd89c944783d00d069f33e3e7123c448
 golang.org/x/sys/unix d75a52659825e75fff6158388dddc6a5b04f9ba5
 # image-spec master as of 1/17/2017
 github.com/opencontainers/image-spec 0ff14aabcda3b2ee62621174f1b29fc157bdf335
+# continuity master as of 2/1/2017
+github.com/stevvooe/continuity 1530f13d23b34e2ccaf33881fefecc7e28e3577b
+# sync master as of 12/5/2016
+golang.org/x/sync 450f422ab23cf9881c94e2db30cac0eb1b7cf80c

vendor/github.com/stevvooe/continuity/LICENSE

@@ -0,0 +1,202 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
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+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
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+      designated in writing by the copyright owner as "Not a Contribution."
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+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
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+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
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+   3. Grant of Patent License. Subject to the terms and conditions of
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+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
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+      or a Contribution incorporated within the Work constitutes direct
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+
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+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
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+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
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+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
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+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
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+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "{}"
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+
+   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.
+

vendor/github.com/stevvooe/continuity/context.go

@@ -0,0 +1,640 @@
+package continuity
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/opencontainers/go-digest"
+)
+
+var (
+	ErrNotFound     = fmt.Errorf("not found")
+	ErrNotSupported = fmt.Errorf("not supported")
+)
+
+// Context represents a file system context for accessing resources. The
+// responsibility of the context is to convert system specific resources to
+// generic Resource objects. Most of this is safe path manipulation, as well
+// as extraction of resource details.
+type Context interface {
+	Apply(Resource) error
+	Verify(Resource) error
+	Resource(string, os.FileInfo) (Resource, error)
+	Walk(filepath.WalkFunc) error
+}
+
+// SymlinkPath is intended to give the symlink target value
+// in a root context. Target and linkname are absolute paths
+// not under the given root.
+type SymlinkPath func(root, linkname, target string) (string, error)
+
+type ContextOptions struct {
+	Digester Digester
+	Driver   Driver
+	Provider ContentProvider
+}
+
+// context represents a file system context for accessing resources.
+// Generally, all path qualified access and system considerations should land
+// here.
+type context struct {
+	driver   Driver
+	root     string
+	digester Digester
+	provider ContentProvider
+}
+
+// NewContext returns a Context associated with root. The default driver will
+// be used, as returned by NewDriver.
+func NewContext(root string) (Context, error) {
+	return NewContextWithOptions(root, ContextOptions{})
+}
+
+// NewContextWithOptions returns a Context associate with the root.
+func NewContextWithOptions(root string, options ContextOptions) (Context, error) {
+	// normalize to absolute path
+	root, err := filepath.Abs(filepath.Clean(root))
+	if err != nil {
+		return nil, err
+	}
+
+	driver := options.Driver
+	if driver == nil {
+		driver, err = NewSystemDriver()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	digester := options.Digester
+	if digester == nil {
+		digester = simpleDigester{digest.Canonical}
+	}
+
+	// Check the root directory. Need to be a little careful here. We are
+	// allowing a link for now, but this may have odd behavior when
+	// canonicalizing paths. As long as all files are opened through the link
+	// path, this should be okay.
+	fi, err := driver.Stat(root)
+	if err != nil {
+		return nil, err
+	}
+
+	if !fi.IsDir() {
+		return nil, &os.PathError{Op: "NewContext", Path: root, Err: os.ErrInvalid}
+	}
+
+	return &context{
+		root:     root,
+		driver:   driver,
+		digester: digester,
+		provider: options.Provider,
+	}, nil
+}
+
+// Resource returns the resource as path p, populating the entry with info
+// from fi. The path p should be the path of the resource in the context,
+// typically obtained through Walk or from the value of Resource.Path(). If fi
+// is nil, it will be resolved.
+func (c *context) Resource(p string, fi os.FileInfo) (Resource, error) {
+	fp, err := c.fullpath(p)
+	if err != nil {
+		return nil, err
+	}
+
+	if fi == nil {
+		fi, err = c.driver.Lstat(fp)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// TODO(stevvooe): This need to be resolved for the container's root,
+	// where here we are really getting the host OS's value. We need to allow
+	// this be passed in and fixed up to make these uid/gid mappings portable.
+	// Either this can be part of the driver or we can achieve it through some
+	// other mechanism.
+	sys, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		// TODO(stevvooe): This may not be a hard error for all platforms. We
+		// may want to move this to the driver.
+		return nil, fmt.Errorf("unable to resolve syscall.Stat_t from (os.FileInfo).Sys(): %#v", fi)
+	}
+
+	base, err := newBaseResource(p, fi.Mode(), fmt.Sprint(sys.Uid), fmt.Sprint(sys.Gid))
+	if err != nil {
+		return nil, err
+	}
+
+	base.xattrs, err = c.resolveXAttrs(fp, fi, base)
+	if err == ErrNotSupported {
+		log.Printf("resolving xattrs on %s not supported", fp)
+	} else if err != nil {
+		return nil, err
+	}
+
+	// TODO(stevvooe): Handle windows alternate data streams.
+
+	if fi.Mode().IsRegular() {
+		dgst, err := c.digest(p)
+		if err != nil {
+			return nil, err
+		}
+
+		return newRegularFile(*base, base.paths, fi.Size(), dgst)
+	}
+
+	if fi.Mode().IsDir() {
+		return newDirectory(*base)
+	}
+
+	if fi.Mode()&os.ModeSymlink != 0 {
+		// We handle relative links vs absolute links by including a
+		// beginning slash for absolute links. Effectively, the bundle's
+		// root is treated as the absolute link anchor.
+		target, err := c.driver.Readlink(fp)
+		if err != nil {
+			return nil, err
+		}
+
+		return newSymLink(*base, target)
+	}
+
+	if fi.Mode()&os.ModeNamedPipe != 0 {
+		return newNamedPipe(*base, base.paths)
+	}
+
+	if fi.Mode()&os.ModeDevice != 0 {
+		deviceDriver, ok := c.driver.(DeviceInfoDriver)
+		if !ok {
+			log.Printf("device extraction not supported %s", fp)
+			return nil, ErrNotSupported
+		}
+
+		// character and block devices merely need to recover the
+		// major/minor device number.
+		major, minor, err := deviceDriver.DeviceInfo(fi)
+		if err != nil {
+			return nil, err
+		}
+
+		return newDevice(*base, base.paths, major, minor)
+	}
+
+	log.Printf("%q (%v) is not supported", fp, fi.Mode())
+	return nil, ErrNotFound
+}
+
+func (c *context) verifyMetadata(resource, target Resource) error {
+	if target.Mode() != resource.Mode() {
+		return fmt.Errorf("resource %q has incorrect mode: %v != %v", target.Path(), target.Mode(), resource.Mode())
+	}
+
+	if target.UID() != resource.UID() {
+		return fmt.Errorf("unexpected uid for %q: %v != %v", target.Path(), target.UID(), resource.GID())
+	}
+
+	if target.GID() != resource.GID() {
+		return fmt.Errorf("unexpected gid for %q: %v != %v", target.Path(), target.GID(), target.GID())
+	}
+
+	if xattrer, ok := resource.(XAttrer); ok {
+		txattrer, tok := target.(XAttrer)
+		if !tok {
+			return fmt.Errorf("resource %q has xattrs but target does not support them", resource.Path())
+		}
+
+		// For xattrs, only ensure that we have those defined in the resource
+		// and their values match. We can ignore other xattrs. In other words,
+		// we only verify that target has the subset defined by resource.
+		txattrs := txattrer.XAttrs()
+		for attr, value := range xattrer.XAttrs() {
+			tvalue, ok := txattrs[attr]
+			if !ok {
+				return fmt.Errorf("resource %q target missing xattr %q", resource.Path(), attr)
+			}
+
+			if !bytes.Equal(value, tvalue) {
+				return fmt.Errorf("xattr %q value differs for resource %q", attr, resource.Path())
+			}
+		}
+	}
+
+	switch r := resource.(type) {
+	case RegularFile:
+		// TODO(stevvooe): Another reason to use a record-based approach. We
+		// have to do another type switch to get this to work. This could be
+		// fixed with an Equal function, but let's study this a little more to
+		// be sure.
+		t, ok := target.(RegularFile)
+		if !ok {
+			return fmt.Errorf("resource %q target not a regular file", r.Path())
+		}
+
+		if t.Size() != r.Size() {
+			return fmt.Errorf("resource %q target has incorrect size: %v != %v", t.Path(), t.Size(), r.Size())
+		}
+	case Directory:
+		t, ok := target.(Directory)
+		if !ok {
+			return fmt.Errorf("resource %q target not a directory", t.Path())
+		}
+	case SymLink:
+		t, ok := target.(SymLink)
+		if !ok {
+			return fmt.Errorf("resource %q target not a symlink", t.Path())
+		}
+
+		if t.Target() != r.Target() {
+			return fmt.Errorf("resource %q target has mismatched target: %q != %q", t.Path(), t.Target(), r.Target())
+		}
+	case Device:
+		t, ok := target.(Device)
+		if !ok {
+			return fmt.Errorf("resource %q is not a device", t.Path())
+		}
+
+		if t.Major() != r.Major() || t.Minor() != r.Minor() {
+			return fmt.Errorf("resource %q has mismatched major/minor numbers: %d,%d != %d,%d", t.Path(), t.Major(), t.Minor(), r.Major(), r.Minor())
+		}
+	case NamedPipe:
+		t, ok := target.(NamedPipe)
+		if !ok {
+			return fmt.Errorf("resource %q is not a named pipe", t.Path())
+		}
+	default:
+		return fmt.Errorf("cannot verify resource: %v", resource)
+	}
+
+	return nil
+}
+
+// Verify the resource in the context. An error will be returned a discrepancy
+// is found.
+func (c *context) Verify(resource Resource) error {
+	fp, err := c.fullpath(resource.Path())
+	if err != nil {
+		return err
+	}
+
+	fi, err := c.driver.Lstat(fp)
+	if err != nil {
+		return err
+	}
+
+	target, err := c.Resource(resource.Path(), fi)
+	if err != nil {
+		return err
+	}
+
+	if target.Path() != resource.Path() {
+		return fmt.Errorf("resource paths do not match: %q != %q", target.Path(), resource.Path())
+	}
+
+	if err := c.verifyMetadata(resource, target); err != nil {
+		return err
+	}
+
+	if h, isHardlinkable := resource.(Hardlinkable); isHardlinkable {
+		hardlinkKey, err := newHardlinkKey(fi)
+		if err == errNotAHardLink {
+			if len(h.Paths()) > 1 {
+				return fmt.Errorf("%q is not a hardlink to %q", h.Paths()[1], resource.Path())
+			}
+		} else if err != nil {
+			return err
+		}
+
+		for _, path := range h.Paths()[1:] {
+			fpLink, err := c.fullpath(path)
+			if err != nil {
+				return err
+			}
+
+			fiLink, err := c.driver.Lstat(fpLink)
+			if err != nil {
+				return err
+			}
+
+			targetLink, err := c.Resource(path, fiLink)
+			if err != nil {
+				return err
+			}
+
+			hardlinkKeyLink, err := newHardlinkKey(fiLink)
+			if err != nil {
+				return err
+			}
+
+			if hardlinkKeyLink != hardlinkKey {
+				return fmt.Errorf("%q is not a hardlink to %q", path, resource.Path())
+			}
+
+			if err := c.verifyMetadata(resource, targetLink); err != nil {
+				return err
+			}
+		}
+	}
+
+	switch r := resource.(type) {
+	case RegularFile:
+		t, ok := target.(RegularFile)
+		if !ok {
+			return fmt.Errorf("resource %q target not a regular file", r.Path())
+		}
+
+		// TODO(stevvooe): This may need to get a little more sophisticated
+		// for digest comparison. We may want to actually calculate the
+		// provided digests, rather than the implementations having an
+		// overlap.
+		if !digestsMatch(t.Digests(), r.Digests()) {
+			return fmt.Errorf("digests for resource %q do not match: %v != %v", t.Path(), t.Digests(), r.Digests())
+		}
+	}
+
+	return nil
+}
+
+func (c *context) checkoutFile(fp string, rf RegularFile) error {
+	if c.provider == nil {
+		return fmt.Errorf("no file provider")
+	}
+	var (
+		r   io.ReadCloser
+		err error
+	)
+	for _, dgst := range rf.Digests() {
+		r, err = c.provider.Reader(dgst)
+		if err == nil {
+			break
+		}
+	}
+	if err != nil {
+		return fmt.Errorf("file content could not be provided: %v", err)
+	}
+	defer r.Close()
+
+	return atomicWriteFile(fp, r, rf)
+}
+
+// Apply the resource to the contexts. An error will be returned if the
+// operation fails. Depending on the resource type, the resource may be
+// created. For resource that cannot be resolved, an error will be returned.
+func (c *context) Apply(resource Resource) error {
+	fp, err := c.fullpath(resource.Path())
+	if err != nil {
+		return err
+	}
+
+	if !strings.HasPrefix(fp, c.root) {
+		return fmt.Errorf("resource %v escapes root", resource)
+	}
+
+	var chmod = true
+	fi, err := c.driver.Lstat(fp)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return err
+		}
+	}
+
+	switch r := resource.(type) {
+	case RegularFile:
+		if fi == nil {
+			if err := c.checkoutFile(fp, r); err != nil {
+				return fmt.Errorf("error checking out file %q: %v", resource.Path(), err)
+			}
+			chmod = false
+		} else {
+			if !fi.Mode().IsRegular() {
+				return fmt.Errorf("file %q should be a regular file, but is not", resource.Path())
+			}
+			if fi.Size() != r.Size() {
+				if err := c.checkoutFile(fp, r); err != nil {
+					return fmt.Errorf("error checking out file %q: %v", resource.Path(), err)
+				}
+			} else {
+				for _, dgst := range r.Digests() {
+					f, err := os.Open(fp)
+					if err != nil {
+						return fmt.Errorf("failure opening file for read %q: %v", resource.Path(), err)
+					}
+					compared, err := dgst.Algorithm().FromReader(f)
+					if err == nil && dgst != compared {
+						if err := c.checkoutFile(fp, r); err != nil {
+							return fmt.Errorf("error checking out file %q: %v", resource.Path(), err)
+						}
+						break
+					}
+					if err1 := f.Close(); err == nil {
+						err = err1
+					}
+					if err != nil {
+						return fmt.Errorf("error checking digest for %q: %v", resource.Path(), err)
+					}
+				}
+			}
+		}
+	case Directory:
+		if fi == nil {
+			if err := c.driver.Mkdir(fp, resource.Mode()); err != nil {
+				return err
+			}
+		} else if !fi.Mode().IsDir() {
+			return fmt.Errorf("%q should be a directory, but is not", resource.Path())
+		}
+
+	case SymLink:
+		var target string // only possibly set if target resource is a symlink
+
+		if fi != nil {
+			if fi.Mode()&os.ModeSymlink != 0 {
+				target, err = c.driver.Readlink(fp)
+				if err != nil {
+					return err
+				}
+			}
+		}
+
+		if target != r.Target() {
+			if err := c.driver.Remove(fp); err != nil { // RemoveAll?
+				return err
+			}
+
+			if err := c.driver.Symlink(r.Target(), fp); err != nil {
+				return err
+			}
+		}
+
+		// NOTE(stevvooe): Chmod on symlink is not supported on linux. We
+		// may want to maintain support for other platforms that have it.
+		chmod = false
+
+	case Device:
+		if fi == nil {
+			if err := c.driver.Mknod(fp, resource.Mode(), int(r.Major()), int(r.Minor())); err != nil {
+				return err
+			}
+		} else if (fi.Mode() & os.ModeDevice) == 0 {
+			return fmt.Errorf("%q should be a device, but is not", resource.Path())
+		} else {
+			major, minor, err := deviceInfo(fi)
+			if err != nil {
+				return err
+			}
+			if major != r.Major() || minor != r.Minor() {
+				if err := c.driver.Remove(fp); err != nil {
+					return err
+				}
+
+				if err := c.driver.Mknod(fp, resource.Mode(), int(r.Major()), int(r.Minor())); err != nil {
+					return err
+				}
+			}
+		}
+
+	case NamedPipe:
+		if fi == nil {
+			if err := c.driver.Mkfifo(fp, resource.Mode()); err != nil {
+				return err
+			}
+		} else if (fi.Mode() & os.ModeNamedPipe) == 0 {
+			return fmt.Errorf("%q should be a named pipe, but is not", resource.Path())
+		}
+	}
+
+	if h, isHardlinkable := resource.(Hardlinkable); isHardlinkable {
+		for _, path := range h.Paths() {
+			if path == resource.Path() {
+				continue
+			}
+
+			lp, err := c.fullpath(path)
+			if err != nil {
+				return err
+			}
+
+			if _, fi := c.driver.Lstat(lp); fi == nil {
+				c.driver.Remove(lp)
+			}
+			if err := c.driver.Link(fp, lp); err != nil {
+				return err
+			}
+		}
+	}
+
+	// Update filemode if file was not created
+	if chmod {
+		if err := c.driver.Lchmod(fp, resource.Mode()); err != nil {
+			return err
+		}
+	}
+
+	if err := c.driver.Lchown(fp, resource.UID(), resource.GID()); err != nil {
+		return err
+	}
+
+	if xattrer, ok := resource.(XAttrer); ok {
+		// For xattrs, only ensure that we have those defined in the resource
+		// and their values are set. We can ignore other xattrs. In other words,
+		// we only set xattres defined by resource but never remove.
+
+		if _, ok := resource.(SymLink); ok {
+			lxattrDriver, ok := c.driver.(LXAttrDriver)
+			if !ok {
+				return fmt.Errorf("unsupported symlink xattr for resource %q", resource.Path())
+			}
+			if err := lxattrDriver.LSetxattr(fp, xattrer.XAttrs()); err != nil {
+				return err
+			}
+		} else {
+			xattrDriver, ok := c.driver.(XAttrDriver)
+			if !ok {
+				return fmt.Errorf("unsupported xattr for resource %q", resource.Path())
+			}
+			if err := xattrDriver.Setxattr(fp, xattrer.XAttrs()); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// Walk provides a convenience function to call filepath.Walk correctly for
+// the context. Otherwise identical to filepath.Walk, the path argument is
+// corrected to be contained within the context.
+func (c *context) Walk(fn filepath.WalkFunc) error {
+	return filepath.Walk(c.root, func(p string, fi os.FileInfo, err error) error {
+		contained, err := c.contain(p)
+		return fn(contained, fi, err)
+	})
+}
+
+// fullpath returns the system path for the resource, joined with the context
+// root. The path p must be a part of the context.
+func (c *context) fullpath(p string) (string, error) {
+	p = filepath.Join(c.root, p)
+	if !strings.HasPrefix(p, c.root) {
+		return "", fmt.Errorf("invalid context path")
+	}
+
+	return p, nil
+}
+
+// contain cleans and santizes the filesystem path p to be an absolute path,
+// effectively relative to the context root.
+func (c *context) contain(p string) (string, error) {
+	sanitized, err := filepath.Rel(c.root, p)
+	if err != nil {
+		return "", err
+	}
+
+	// ZOMBIES(stevvooe): In certain cases, we may want to remap these to a
+	// "containment error", so the caller can decide what to do.
+	return filepath.Join("/", filepath.Clean(sanitized)), nil
+}
+
+// digest returns the digest of the file at path p, relative to the root.
+func (c *context) digest(p string) (digest.Digest, error) {
+	f, err := c.driver.Open(filepath.Join(c.root, p))
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	return c.digester.Digest(f)
+}
+
+// resolveXAttrs attempts to resolve the extended attributes for the resource
+// at the path fp, which is the full path to the resource. If the resource
+// cannot have xattrs, nil will be returned.
+func (c *context) resolveXAttrs(fp string, fi os.FileInfo, base *resource) (map[string][]byte, error) {
+	if fi.Mode().IsRegular() || fi.Mode().IsDir() {
+		xattrDriver, ok := c.driver.(XAttrDriver)
+		if !ok {
+			log.Println("xattr extraction not supported")
+			return nil, ErrNotSupported
+		}
+
+		return xattrDriver.Getxattr(fp)
+	}
+
+	if fi.Mode()&os.ModeSymlink != 0 {
+		lxattrDriver, ok := c.driver.(LXAttrDriver)
+		if !ok {
+			log.Println("xattr extraction for symlinks not supported")
+			return nil, ErrNotSupported
+		}
+
+		return lxattrDriver.LGetxattr(fp)
+	}
+
+	return nil, nil
+}

vendor/github.com/stevvooe/continuity/devices_darwin.go

@@ -0,0 +1,15 @@
+package continuity
+
+// from /usr/include/sys/types.h
+
+func getmajor(dev int32) uint64 {
+	return (uint64(dev) >> 24) & 0xff
+}
+
+func getminor(dev int32) uint64 {
+	return uint64(dev) & 0xffffff
+}
+
+func makedev(major int, minor int) int {
+	return ((major << 24) | minor)
+}

vendor/github.com/stevvooe/continuity/devices_linux.go

@@ -0,0 +1,15 @@
+package continuity
+
+// from /usr/include/linux/kdev_t.h
+
+func getmajor(dev uint64) uint64 {
+	return dev >> 8
+}
+
+func getminor(dev uint64) uint64 {
+	return dev & 0xff
+}
+
+func makedev(major int, minor int) int {
+	return ((major << 8) | minor)
+}

vendor/github.com/stevvooe/continuity/devices_unix.go

@@ -0,0 +1,55 @@
+// +build linux darwin
+
+package continuity
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+)
+
+func deviceInfo(fi os.FileInfo) (uint64, uint64, error) {
+	sys, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return 0, 0, fmt.Errorf("cannot extract device from os.FileInfo")
+	}
+
+	return getmajor(sys.Rdev), getminor(sys.Rdev), nil
+}
+
+// mknod provides a shortcut for syscall.Mknod
+func mknod(p string, mode os.FileMode, maj, min int) error {
+	var (
+		m   = syscallMode(mode.Perm())
+		dev int
+	)
+
+	if mode&os.ModeDevice != 0 {
+		dev = makedev(maj, min)
+
+		if mode&os.ModeCharDevice != 0 {
+			m |= syscall.S_IFCHR
+		} else {
+			m |= syscall.S_IFBLK
+		}
+	} else if mode&os.ModeNamedPipe != 0 {
+		m |= syscall.S_IFIFO
+	}
+
+	return syscall.Mknod(p, m, dev)
+}
+
+// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
+func syscallMode(i os.FileMode) (o uint32) {
+	o |= uint32(i.Perm())
+	if i&os.ModeSetuid != 0 {
+		o |= syscall.S_ISUID
+	}
+	if i&os.ModeSetgid != 0 {
+		o |= syscall.S_ISGID
+	}
+	if i&os.ModeSticky != 0 {
+		o |= syscall.S_ISVTX
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/digests.go

@@ -0,0 +1,88 @@
+package continuity
+
+import (
+	"fmt"
+	"io"
+	"sort"
+
+	"github.com/opencontainers/go-digest"
+)
+
+// Digester produces a digest for a given read stream
+type Digester interface {
+	Digest(io.Reader) (digest.Digest, error)
+}
+
+// ContentProvider produces a read stream for a given digest
+type ContentProvider interface {
+	Reader(digest.Digest) (io.ReadCloser, error)
+}
+
+type simpleDigester struct {
+	algorithm digest.Algorithm
+}
+
+func (sd simpleDigester) Digest(r io.Reader) (digest.Digest, error) {
+	digester := sd.algorithm.Digester()
+
+	if _, err := io.Copy(digester.Hash(), r); err != nil {
+		return "", err
+	}
+
+	return digester.Digest(), nil
+}
+
+// uniqifyDigests sorts and uniqifies the provided digest, ensuring that the
+// digests are not repeated and no two digests with the same algorithm have
+// different values. Because a stable sort is used, this has the effect of
+// "zipping" digest collections from multiple resources.
+func uniqifyDigests(digests ...digest.Digest) ([]digest.Digest, error) {
+	sort.Stable(digestSlice(digests)) // stable sort is important for the behavior here.
+	seen := map[digest.Digest]struct{}{}
+	algs := map[digest.Algorithm][]digest.Digest{} // detect different digests.
+
+	var out []digest.Digest
+	// uniqify the digests
+	for _, d := range digests {
+		if _, ok := seen[d]; ok {
+			continue
+		}
+
+		seen[d] = struct{}{}
+		algs[d.Algorithm()] = append(algs[d.Algorithm()], d)
+
+		if len(algs[d.Algorithm()]) > 1 {
+			return nil, fmt.Errorf("conflicting digests for %v found", d.Algorithm())
+		}
+
+		out = append(out, d)
+	}
+
+	return out, nil
+}
+
+// digestsMatch compares the two sets of digests to see if they match.
+func digestsMatch(as, bs []digest.Digest) bool {
+	all := append(as, bs...)
+
+	uniqified, err := uniqifyDigests(all...)
+	if err != nil {
+		// the only error uniqifyDigests returns is when the digests disagree.
+		return false
+	}
+
+	disjoint := len(as) + len(bs)
+	if len(uniqified) == disjoint {
+		// if these two sets have the same cardinality, we know both sides
+		// didn't share any digests.
+		return false
+	}
+
+	return true
+}
+
+type digestSlice []digest.Digest
+
+func (p digestSlice) Len() int           { return len(p) }
+func (p digestSlice) Less(i, j int) bool { return p[i] < p[j] }
+func (p digestSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }

vendor/github.com/stevvooe/continuity/driver.go

@@ -0,0 +1,158 @@
+package continuity
+
+import (
+	"errors"
+	"os"
+	"strconv"
+)
+
+// Driver provides all of the system-level functions in a common interface.
+// The context should call these with full paths and should never use the `os`
+// package or any other package to access resources on the filesystem. This
+// mechanism let's us carefully control access to the context and maintain
+// path and resource integrity. It also gives us an interface to reason about
+// direct resource access.
+//
+// Implementations don't need to do much other than meet the interface. For
+// example, it is not required to wrap os.FileInfo to return correct paths for
+// the call to Name().
+type Driver interface {
+	Open(path string) (*os.File, error)
+	Stat(path string) (os.FileInfo, error)
+	Lstat(path string) (os.FileInfo, error)
+	Readlink(p string) (string, error)
+	Mkdir(path string, mode os.FileMode) error
+	Remove(path string) error
+
+	Link(oldname, newname string) error
+	Lchmod(path string, mode os.FileMode) error
+	Lchown(path, uid, gid string) error
+	Symlink(oldname, newname string) error
+
+	// TODO(aaronl): These methods might move outside the main Driver
+	// interface in the future as more platforms are added.
+	Mknod(path string, mode os.FileMode, major int, minor int) error
+	Mkfifo(path string, mode os.FileMode) error
+
+	// NOTE(stevvooe): We may want to actually include the path manipulation
+	// functions here, as well. They have been listed below to make the
+	// discovery process easier.
+
+	// Join(path ...string) string
+	// IsAbs(string) bool
+	// Abs(string) (string, error)
+	// Rel(base, target string) (string, error)
+	// Walk(string, filepath.WalkFunc) error
+}
+
+func NewSystemDriver() (Driver, error) {
+	// TODO(stevvooe): Consider having this take a "hint" path argument, which
+	// would be the context root. The hint could be used to resolve required
+	// filesystem support when assembling the driver to use.
+	return &driver{}, nil
+}
+
+// XAttrDriver should be implemented on operation systems and filesystems that
+// have xattr support for regular files and directories.
+type XAttrDriver interface {
+	// Getxattr returns all of the extended attributes for the file at path.
+	// Typically, this takes a syscall call to Listxattr and Getxattr.
+	Getxattr(path string) (map[string][]byte, error)
+
+	// Setxattr sets all of the extended attributes on file at path, following
+	// any symbolic links, if necessary. All attributes on the target are
+	// replaced by the values from attr. If the operation fails to set any
+	// attribute, those already applied will not be rolled back.
+	Setxattr(path string, attr map[string][]byte) error
+}
+
+// LXAttrDriver should be implemented by drivers on operating systems and
+// filesystems that support setting and getting extended attributes on
+// symbolic links. If this is not implemented, extended attributes will be
+// ignored on symbolic links.
+type LXAttrDriver interface {
+	// LGetxattr returns all of the extended attributes for the file at path
+	// and does not follow symlinks. Typically, this takes a syscall call to
+	// Llistxattr and Lgetxattr.
+	LGetxattr(path string) (map[string][]byte, error)
+
+	// LSetxattr sets all of the extended attributes on file at path, without
+	// following symbolic links. All attributes on the target are replaced by
+	// the values from attr. If the operation fails to set any attribute,
+	// those already applied will not be rolled back.
+	LSetxattr(path string, attr map[string][]byte) error
+}
+
+type DeviceInfoDriver interface {
+	DeviceInfo(fi os.FileInfo) (maj uint64, min uint64, err error)
+}
+
+// driver is a simple default implementation that sends calls out to the "os"
+// package. Extend the "driver" type in system-specific files to add support,
+// such as xattrs, which can add support at compile time.
+type driver struct{}
+
+var _ Driver = &driver{}
+
+func (d *driver) Open(p string) (*os.File, error) {
+	return os.Open(p)
+}
+
+func (d *driver) Stat(p string) (os.FileInfo, error) {
+	return os.Stat(p)
+}
+
+func (d *driver) Lstat(p string) (os.FileInfo, error) {
+	return os.Lstat(p)
+}
+
+func (d *driver) Readlink(p string) (string, error) {
+	return os.Readlink(p)
+}
+
+func (d *driver) Mkdir(p string, mode os.FileMode) error {
+	return os.Mkdir(p, mode)
+}
+
+// Remove is used to unlink files and remove directories.
+// This is following the golang os package api which
+// combines the operations into a higher level Remove
+// function. If explicit unlinking or directory removal
+// to mirror system call is required, they should be
+// split up at that time.
+func (d *driver) Remove(path string) error {
+	return os.Remove(path)
+}
+
+func (d *driver) Link(oldname, newname string) error {
+	return os.Link(oldname, newname)
+}
+
+func (d *driver) Lchown(name, uidStr, gidStr string) error {
+	uid, err := strconv.Atoi(uidStr)
+	if err != nil {
+		return err
+	}
+	gid, err := strconv.Atoi(gidStr)
+	if err != nil {
+		return err
+	}
+	return os.Lchown(name, uid, gid)
+}
+
+func (d *driver) Symlink(oldname, newname string) error {
+	return os.Symlink(oldname, newname)
+}
+
+func (d *driver) Mknod(path string, mode os.FileMode, major, minor int) error {
+	return mknod(path, mode, major, minor)
+}
+
+func (d *driver) Mkfifo(path string, mode os.FileMode) error {
+	if mode&os.ModeNamedPipe == 0 {
+		return errors.New("mode passed to Mkfifo does not have the named pipe bit set")
+	}
+	// mknod with a mode that has ModeNamedPipe set creates a fifo, not a
+	// device.
+	return mknod(path, mode, 0, 0)
+}

vendor/github.com/stevvooe/continuity/driver_darwin.go

@@ -0,0 +1,7 @@
+package continuity
+
+import "os"
+
+func (d *driver) DeviceInfo(fi os.FileInfo) (maj uint64, min uint64, err error) {
+	return deviceInfo(fi)
+}

vendor/github.com/stevvooe/continuity/driver_unix.go

@@ -0,0 +1,107 @@
+// +build linux darwin
+
+package continuity
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+
+	"github.com/stevvooe/continuity/sysx"
+)
+
+// Lchmod changes the mode of an file not following symlinks.
+func (d *driver) Lchmod(path string, mode os.FileMode) (err error) {
+	if !filepath.IsAbs(path) {
+		path, err = filepath.Abs(path)
+		if err != nil {
+			return
+		}
+	}
+
+	return sysx.Fchmodat(0, path, uint32(mode), sysx.AtSymlinkNofollow)
+}
+
+// Getxattr returns all of the extended attributes for the file at path p.
+func (d *driver) Getxattr(p string) (map[string][]byte, error) {
+	xattrs, err := sysx.Listxattr(p)
+	if err != nil {
+		return nil, fmt.Errorf("listing %s xattrs: %v", p, err)
+	}
+
+	sort.Strings(xattrs)
+	m := make(map[string][]byte, len(xattrs))
+
+	for _, attr := range xattrs {
+		value, err := sysx.Getxattr(p, attr)
+		if err != nil {
+			return nil, fmt.Errorf("getting %q xattr on %s: %v", attr, p, err)
+		}
+
+		// NOTE(stevvooe): This append/copy tricky relies on unique
+		// xattrs. Break this out into an alloc/copy if xattrs are no
+		// longer unique.
+		m[attr] = append(m[attr], value...)
+	}
+
+	return m, nil
+}
+
+// Setxattr sets all of the extended attributes on file at path, following
+// any symbolic links, if necessary. All attributes on the target are
+// replaced by the values from attr. If the operation fails to set any
+// attribute, those already applied will not be rolled back.
+func (d *driver) Setxattr(path string, attrMap map[string][]byte) error {
+	for attr, value := range attrMap {
+		if err := sysx.Setxattr(path, attr, value, 0); err != nil {
+			return fmt.Errorf("error setting xattr %q on %s: %v", attr, path, err)
+		}
+	}
+
+	return nil
+}
+
+// LGetxattr returns all of the extended attributes for the file at path p
+// not following symbolic links.
+func (d *driver) LGetxattr(p string) (map[string][]byte, error) {
+	xattrs, err := sysx.LListxattr(p)
+	if err != nil {
+		return nil, fmt.Errorf("listing %s xattrs: %v", p, err)
+	}
+
+	sort.Strings(xattrs)
+	m := make(map[string][]byte, len(xattrs))
+
+	for _, attr := range xattrs {
+		value, err := sysx.LGetxattr(p, attr)
+		if err != nil {
+			return nil, fmt.Errorf("getting %q xattr on %s: %v", attr, p, err)
+		}
+
+		// NOTE(stevvooe): This append/copy tricky relies on unique
+		// xattrs. Break this out into an alloc/copy if xattrs are no
+		// longer unique.
+		m[attr] = append(m[attr], value...)
+	}
+
+	return m, nil
+}
+
+// LSetxattr sets all of the extended attributes on file at path, not
+// following any symbolic links. All attributes on the target are
+// replaced by the values from attr. If the operation fails to set any
+// attribute, those already applied will not be rolled back.
+func (d *driver) LSetxattr(path string, attrMap map[string][]byte) error {
+	for attr, value := range attrMap {
+		if err := sysx.LSetxattr(path, attr, value, 0); err != nil {
+			return fmt.Errorf("error setting xattr %q on %s: %v", attr, path, err)
+		}
+	}
+
+	return nil
+}
+
+func (d *driver) DeviceInfo(fi os.FileInfo) (maj uint64, min uint64, err error) {
+	return deviceInfo(fi)
+}

vendor/github.com/stevvooe/continuity/groups_unix.go

@@ -0,0 +1,113 @@
+package continuity
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// TODO(stevvooe): This needs a lot of work before we can call it useful.
+
+type groupIndex struct {
+	byName map[string]*group
+	byGID  map[int]*group
+}
+
+func getGroupIndex() (*groupIndex, error) {
+	f, err := os.Open("/etc/group")
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	groups, err := parseGroups(f)
+	if err != nil {
+		return nil, err
+	}
+
+	return newGroupIndex(groups), nil
+}
+
+func newGroupIndex(groups []group) *groupIndex {
+	gi := &groupIndex{
+		byName: make(map[string]*group),
+		byGID:  make(map[int]*group),
+	}
+
+	for i, group := range groups {
+		gi.byGID[group.gid] = &groups[i]
+		gi.byName[group.name] = &groups[i]
+	}
+
+	return gi
+}
+
+type group struct {
+	name    string
+	gid     int
+	members []string
+}
+
+func getGroupName(gid int) (string, error) {
+	f, err := os.Open("/etc/group")
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	groups, err := parseGroups(f)
+	if err != nil {
+		return "", err
+	}
+
+	for _, group := range groups {
+		if group.gid == gid {
+			return group.name, nil
+		}
+	}
+
+	return "", fmt.Errorf("no group for gid")
+}
+
+// parseGroups parses an /etc/group file for group names, ids and membership.
+// This is unix specific.
+func parseGroups(rd io.Reader) ([]group, error) {
+	var groups []group
+	scanner := bufio.NewScanner(rd)
+
+	for scanner.Scan() {
+		if strings.HasPrefix(scanner.Text(), "#") {
+			continue // skip comment
+		}
+
+		parts := strings.SplitN(scanner.Text(), ":", 4)
+
+		if len(parts) != 4 {
+			return nil, fmt.Errorf("bad entry: %q", scanner.Text())
+		}
+
+		name, _, sgid, smembers := parts[0], parts[1], parts[2], parts[3]
+
+		gid, err := strconv.Atoi(sgid)
+		if err != nil {
+			return nil, fmt.Errorf("bad gid: %q", gid)
+		}
+
+		members := strings.Split(smembers, ",")
+
+		groups = append(groups, group{
+			name:    name,
+			gid:     gid,
+			members: members,
+		})
+	}
+
+	if scanner.Err() != nil {
+		return nil, scanner.Err()
+	}
+
+	return groups, nil
+}

vendor/github.com/stevvooe/continuity/hardlinks.go

@@ -0,0 +1,57 @@
+package continuity
+
+import (
+	"fmt"
+	"os"
+)
+
+var (
+	errNotAHardLink = fmt.Errorf("invalid hardlink")
+)
+
+type hardlinkManager struct {
+	hardlinks map[hardlinkKey][]Resource
+}
+
+func newHardlinkManager() *hardlinkManager {
+	return &hardlinkManager{
+		hardlinks: map[hardlinkKey][]Resource{},
+	}
+}
+
+// Add attempts to add the resource to the hardlink manager. If the resource
+// cannot be considered as a hardlink candidate, errNotAHardLink is returned.
+func (hlm *hardlinkManager) Add(fi os.FileInfo, resource Resource) error {
+	if _, ok := resource.(Hardlinkable); !ok {
+		return errNotAHardLink
+	}
+
+	key, err := newHardlinkKey(fi)
+	if err != nil {
+		return err
+	}
+
+	hlm.hardlinks[key] = append(hlm.hardlinks[key], resource)
+
+	return nil
+}
+
+// Merge processes the current state of the hardlink manager and merges any
+// shared nodes into hardlinked resources.
+func (hlm *hardlinkManager) Merge() ([]Resource, error) {
+	var resources []Resource
+	for key, linked := range hlm.hardlinks {
+		if len(linked) < 1 {
+			return nil, fmt.Errorf("no hardlink entrys for dev, inode pair: %#v", key)
+		}
+
+		merged, err := Merge(linked...)
+		if err != nil {
+			return nil, fmt.Errorf("error merging hardlink: %v", err)
+		}
+
+		resources = append(resources, merged)
+	}
+
+	return resources, nil
+}

vendor/github.com/stevvooe/continuity/hardlinks_unix.go

@@ -0,0 +1,34 @@
+package continuity
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+)
+
+// hardlinkKey provides a tuple-key for managing hardlinks. This is system-
+// specific.
+type hardlinkKey struct {
+	dev   uint64
+	inode uint64
+}
+
+// newHardlinkKey returns a hardlink key for the provided file info. If the
+// resource does not represent a possible hardlink, errNotAHardLink will be
+// returned.
+func newHardlinkKey(fi os.FileInfo) (hardlinkKey, error) {
+	sys, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return hardlinkKey{}, fmt.Errorf("cannot resolve (*syscall.Stat_t) from os.FileInfo")
+	}
+
+	if sys.Nlink < 2 {
+		// NOTE(stevvooe): This is not always true for all filesystems. We
+		// should somehow detect this and provided a slow "polyfill" that
+		// leverages os.SameFile if we detect a filesystem where link counts
+		// is not really supported.
+		return hardlinkKey{}, errNotAHardLink
+	}
+
+	return hardlinkKey{dev: uint64(sys.Dev), inode: sys.Ino}, nil
+}

vendor/github.com/stevvooe/continuity/hardlinks_windows.go

@@ -0,0 +1,5 @@
+package continuity
+
+// NOTE(stevvooe): Obviously, this is not yet implemented. However, the
+// makings of an implementation are available in src/os/types_windows.go. More
+// investigation needs to be done to figure out exactly how to do this.

vendor/github.com/stevvooe/continuity/ioutils.go

@@ -0,0 +1,39 @@
+package continuity
+
+import (
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+// atomicWriteFile writes data to a file by first writing to a temp
+// file and calling rename.
+func atomicWriteFile(filename string, r io.Reader, rf RegularFile) error {
+	f, err := ioutil.TempFile(filepath.Dir(filename), ".tmp-"+filepath.Base(filename))
+	if err != nil {
+		return err
+	}
+	err = os.Chmod(f.Name(), rf.Mode())
+	if err != nil {
+		f.Close()
+		return err
+	}
+	n, err := io.Copy(f, r)
+	if err == nil && n < rf.Size() {
+		f.Close()
+		return io.ErrShortWrite
+	}
+	if err != nil {
+		f.Close()
+		return err
+	}
+	if err := f.Sync(); err != nil {
+		f.Close()
+		return err
+	}
+	if err := f.Close(); err != nil {
+		return err
+	}
+	return os.Rename(f.Name(), filename)
+}

vendor/github.com/stevvooe/continuity/manifest.go

@@ -0,0 +1,144 @@
+package continuity
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"sort"
+
+	"github.com/golang/protobuf/proto"
+	pb "github.com/stevvooe/continuity/proto"
+)
+
+// Manifest provides the contents of a manifest. Users of this struct should
+// not typically modify any fields directly.
+type Manifest struct {
+	// Resources specifies all the resources for a manifest in order by path.
+	Resources []Resource
+}
+
+func Unmarshal(p []byte) (*Manifest, error) {
+	var bm pb.Manifest
+
+	if err := proto.Unmarshal(p, &bm); err != nil {
+		return nil, err
+	}
+
+	var m Manifest
+	for _, b := range bm.Resource {
+		r, err := fromProto(b)
+		if err != nil {
+			return nil, err
+		}
+
+		m.Resources = append(m.Resources, r)
+	}
+
+	return &m, nil
+}
+
+func Marshal(m *Manifest) ([]byte, error) {
+	var bm pb.Manifest
+	for _, resource := range m.Resources {
+		bm.Resource = append(bm.Resource, toProto(resource))
+	}
+
+	return proto.Marshal(&bm)
+}
+
+func MarshalText(w io.Writer, m *Manifest) error {
+	var bm pb.Manifest
+	for _, resource := range m.Resources {
+		bm.Resource = append(bm.Resource, toProto(resource))
+	}
+
+	return proto.MarshalText(w, &bm)
+}
+
+// BuildManifest creates the manifest for the given context
+func BuildManifest(ctx Context) (*Manifest, error) {
+	resourcesByPath := map[string]Resource{}
+	hardlinks := newHardlinkManager()
+
+	if err := ctx.Walk(func(p string, fi os.FileInfo, err error) error {
+		if err != nil {
+			return fmt.Errorf("error walking %s: %v", p, err)
+		}
+
+		if p == "/" {
+			// skip root
+			return nil
+		}
+
+		resource, err := ctx.Resource(p, fi)
+		if err != nil {
+			if err == ErrNotFound {
+				return nil
+			}
+			log.Printf("error getting resource %q: %v", p, err)
+			return err
+		}
+
+		// add to the hardlink manager
+		if err := hardlinks.Add(fi, resource); err == nil {
+			// Resource has been accepted by hardlink manager so we don't add
+			// it to the resourcesByPath until we merge at the end.
+			return nil
+		} else if err != errNotAHardLink {
+			// handle any other case where we have a proper error.
+			return fmt.Errorf("adding hardlink %s: %v", p, err)
+		}
+
+		resourcesByPath[p] = resource
+
+		return nil
+	}); err != nil {
+		return nil, err
+	}
+
+	// merge and post-process the hardlinks.
+	hardlinked, err := hardlinks.Merge()
+	if err != nil {
+		return nil, err
+	}
+
+	for _, resource := range hardlinked {
+		resourcesByPath[resource.Path()] = resource
+	}
+
+	var resources []Resource
+	for _, resource := range resourcesByPath {
+		resources = append(resources, resource)
+	}
+
+	sort.Stable(ByPath(resources))
+
+	return &Manifest{
+		Resources: resources,
+	}, nil
+}
+
+// VerifyManifest verifies all the resources in a manifest
+// against files from the given context.
+func VerifyManifest(ctx Context, manifest *Manifest) error {
+	for _, resource := range manifest.Resources {
+		if err := ctx.Verify(resource); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// ApplyManifest applies on the resources in a manifest to
+// the given context.
+func ApplyManifest(ctx Context, manifest *Manifest) error {
+	for _, resource := range manifest.Resources {
+		if err := ctx.Apply(resource); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

vendor/github.com/stevvooe/continuity/manifest_test_darwin.go

@@ -0,0 +1,23 @@
+// +build ignore
+
+package continuity
+
+import "os"
+
+var (
+	devNullResource = resource{
+		kind:  chardev,
+		path:  "/dev/null",
+		major: 3,
+		minor: 2,
+		mode:  0666 | os.ModeDevice | os.ModeCharDevice,
+	}
+
+	devZeroResource = resource{
+		kind:  chardev,
+		path:  "/dev/zero",
+		major: 3,
+		minor: 3,
+		mode:  0666 | os.ModeDevice | os.ModeCharDevice,
+	}
+)

vendor/github.com/stevvooe/continuity/proto/gen.go

@@ -0,0 +1,3 @@
+package proto
+
+//go:generate protoc --go_out=. manifest.proto

vendor/github.com/stevvooe/continuity/proto/manifest.pb.go

@@ -0,0 +1,98 @@
+// Code generated by protoc-gen-go.
+// source: manifest.proto
+// DO NOT EDIT!
+
+/*
+Package proto is a generated protocol buffer package.
+
+It is generated from these files:
+	manifest.proto
+
+It has these top-level messages:
+	Manifest
+	Resource
+*/
+package proto
+
+import proto1 "github.com/golang/protobuf/proto"
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto1.Marshal
+
+// Manifest specifies the entries in a container bundle, keyed and sorted by
+// path.
+type Manifest struct {
+	Resource []*Resource `protobuf:"bytes,1,rep,name=resource" json:"resource,omitempty"`
+}
+
+func (m *Manifest) Reset()         { *m = Manifest{} }
+func (m *Manifest) String() string { return proto1.CompactTextString(m) }
+func (*Manifest) ProtoMessage()    {}
+
+func (m *Manifest) GetResource() []*Resource {
+	if m != nil {
+		return m.Resource
+	}
+	return nil
+}
+
+type Resource struct {
+	// Path specifies the path from the bundle root. If more than one
+	// path is present, the entry may represent a hardlink, rather than using
+	// a link target. The path format is operating system specific.
+	Path []string `protobuf:"bytes,1,rep,name=path" json:"path,omitempty"`
+	// Uid specifies the user id for the resource. A string type is used for
+	// compatibility across different OS.
+	Uid string `protobuf:"bytes,2,opt,name=uid" json:"uid,omitempty"`
+	// Gid specifies the group id for the resource. A string type is used for
+	// compatibility across different OS.
+	Gid string `protobuf:"bytes,3,opt,name=gid" json:"gid,omitempty"`
+	// user and group are not currently used but their field numbers have been
+	// reserved for future use. As such, they are marked as deprecated.
+	User  string `protobuf:"bytes,4,opt,name=user" json:"user,omitempty"`
+	Group string `protobuf:"bytes,5,opt,name=group" json:"group,omitempty"`
+	// Mode defines the file mode and permissions. We've used the same
+	// bit-packing from Go's os package,
+	// http://golang.org/pkg/os/#FileMode, since they've done the work of
+	// creating a cross-platform layout.
+	Mode uint32 `protobuf:"varint,6,opt,name=mode" json:"mode,omitempty"`
+	// Size specifies the size in bytes of the resource. This is only valid
+	// for regular files.
+	Size uint64 `protobuf:"varint,7,opt,name=size" json:"size,omitempty"`
+	// Digest specifies the content digest of the target file. Only valid for
+	// regular files. The strings are formatted as <alg>:<digest hex bytes>.
+	// The digests are sorted in lexical order and implementations may choose
+	// which algorithms they prefer.
+	Digest []string `protobuf:"bytes,8,rep,name=digest" json:"digest,omitempty"`
+	// Target defines the target of a hard or soft link. Absolute links start
+	// with a slash and specify the resource relative to the bundle root.
+	// Relative links do not start with a slash and are relative to the
+	// resource path.
+	Target string `protobuf:"bytes,9,opt,name=target" json:"target,omitempty"`
+	// Major specifies the major device number for charactor and block devices.
+	Major uint64 `protobuf:"varint,10,opt,name=major" json:"major,omitempty"`
+	// Minor specifies the minor device number for charactor and block devices.
+	Minor uint64 `protobuf:"varint,11,opt,name=minor" json:"minor,omitempty"`
+	// Xattr provides storage for extended attributes for the target resource.
+	Xattr map[string][]byte `protobuf:"bytes,12,rep,name=xattr" json:"xattr,omitempty" protobuf_key:"bytes,1,opt,name=key" protobuf_val:"bytes,2,opt,name=value,proto3"`
+	// Ads stores one or more alternate data streams for the target resource.
+	Ads map[string][]byte `protobuf:"bytes,13,rep,name=ads" json:"ads,omitempty" protobuf_key:"bytes,1,opt,name=key" protobuf_val:"bytes,2,opt,name=value,proto3"`
+}
+
+func (m *Resource) Reset()         { *m = Resource{} }
+func (m *Resource) String() string { return proto1.CompactTextString(m) }
+func (*Resource) ProtoMessage()    {}
+
+func (m *Resource) GetXattr() map[string][]byte {
+	if m != nil {
+		return m.Xattr
+	}
+	return nil
+}
+
+func (m *Resource) GetAds() map[string][]byte {
+	if m != nil {
+		return m.Ads
+	}
+	return nil
+}

vendor/github.com/stevvooe/continuity/proto/manifest.proto

@@ -0,0 +1,77 @@
+syntax = "proto3";
+
+package proto;
+
+// Manifest specifies the entries in a container bundle, keyed and sorted by
+// path.
+message Manifest {
+    repeated Resource resource = 1;
+}
+
+message Resource {
+    // Path specifies the path from the bundle root. If more than one
+    // path is present, the entry may represent a hardlink, rather than using
+    // a link target. The path format is operating system specific.
+    repeated string path = 1;
+
+    // NOTE(stevvooe): Need to define clear precedence for user/group/uid/gid precedence.
+
+    // Uid specifies the user id for the resource. A string type is used for
+    // compatibility across different OS.
+    string uid = 2;
+
+    // Gid specifies the group id for the resource. A string type is used for
+    // compatibility across different OS.
+    string gid = 3;
+
+    // user and group are not currently used but their field numbers have been
+    // reserved for future use. As such, they are marked as deprecated.
+    string user = 4 [deprecated=true];
+    string group = 5 [deprecated=true];
+
+    // Mode defines the file mode and permissions. We've used the same
+    // bit-packing from Go's os package,
+    // http://golang.org/pkg/os/#FileMode, since they've done the work of
+    // creating a cross-platform layout.
+    uint32 mode = 6;
+
+    // NOTE(stevvooe): Beyond here, we start defining type specific fields.
+
+    // Size specifies the size in bytes of the resource. This is only valid
+    // for regular files.
+    uint64 size = 7;
+
+    // Digest specifies the content digest of the target file. Only valid for
+    // regular files. The strings are formatted as <alg>:<digest hex bytes>.
+    // The digests are sorted in lexical order and implementations may choose
+    // which algorithms they prefer.
+    repeated string digest = 8;
+
+    // Target defines the target of a hard or soft link. Absolute links start
+    // with a slash and specify the resource relative to the bundle root.
+    // Relative links do not start with a slash and are relative to the
+    // resource path.
+    string target = 9;
+
+    // Major specifies the major device number for charactor and block devices.
+    uint64 major = 10;
+
+    // Minor specifies the minor device number for charactor and block devices.
+    uint64 minor = 11;
+
+    // TODO(stevvooe): The use of maps here may be problematic for
+    // deterministic generation. Check out this comment:
+    // https://developers.google.com/protocol-buffers/docs/proto3#backwards-compatibility
+    // Fortunately, the Go implementation correctly sorts the map keys to
+    // ensure deterministic generation, but this is not guaranteed for all
+    // implementations. If this is problem, we should generate that schema and
+    // sort by key. We can do this at any time and retain backwards
+    // compatibility.
+
+    // Xattr provides storage for extended attributes for the target resource.
+    map<string, bytes> xattr = 12;
+
+    // Ads stores one or more alternate data streams for the target resource.
+    map<string, bytes> ads = 13;
+
+}

vendor/github.com/stevvooe/continuity/resource.go

@@ -0,0 +1,578 @@
+package continuity
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"reflect"
+	"sort"
+
+	"github.com/opencontainers/go-digest"
+	pb "github.com/stevvooe/continuity/proto"
+)
+
+// TODO(stevvooe): A record based model, somewhat sketched out at the bottom
+// of this file, will be more flexible. Another possibly is to tie the package
+// interface directly to the protobuf type. This will have efficiency
+// advantages at the cost coupling the nasty codegen types to the exported
+// interface.
+
+type Resource interface {
+	// Path provides the primary resource path relative to the bundle root. In
+	// cases where resources have more than one path, such as with hard links,
+	// this will return the primary path, which is often just the first entry.
+	Path() string
+
+	// Mode returns the
+	Mode() os.FileMode
+
+	UID() string
+	GID() string
+}
+
+// ByPath provides the canonical sort order for a set of resources. Use with
+// sort.Stable for deterministic sorting.
+type ByPath []Resource
+
+func (bp ByPath) Len() int           { return len(bp) }
+func (bp ByPath) Swap(i, j int)      { bp[i], bp[j] = bp[j], bp[i] }
+func (bp ByPath) Less(i, j int) bool { return bp[i].Path() < bp[j].Path() }
+
+type XAttrer interface {
+	XAttrs() map[string][]byte
+}
+
+// Hardlinkable is an interface that a resource type satisfies if it can be a
+// hardlink target.
+type Hardlinkable interface {
+	// Paths returns all paths of the resource, including the primary path
+	// returned by Resource.Path. If len(Paths()) > 1, the resource is a hard
+	// link.
+	Paths() []string
+}
+
+type RegularFile interface {
+	Resource
+	XAttrer
+	Hardlinkable
+
+	Size() int64
+	Digests() []digest.Digest
+}
+
+// Merge two or more Resources into new file. Typically, this should be
+// used to merge regular files as hardlinks. If the files are not identical,
+// other than Paths and Digests, the merge will fail and an error will be
+// returned.
+func Merge(fs ...Resource) (Resource, error) {
+	if len(fs) < 1 {
+		return nil, fmt.Errorf("please provide a resource to merge")
+	}
+
+	if len(fs) == 1 {
+		return fs[0], nil
+	}
+
+	var paths []string
+	var digests []digest.Digest
+	bypath := map[string][]Resource{}
+
+	// The attributes are all compared against the first to make sure they
+	// agree before adding to the above collections. If any of these don't
+	// correctly validate, the merge fails.
+	prototype := fs[0]
+	xattrs := make(map[string][]byte)
+
+	// initialize xattrs for use below. All files must have same xattrs.
+	if prototypeXAttrer, ok := prototype.(XAttrer); ok {
+		for attr, value := range prototypeXAttrer.XAttrs() {
+			xattrs[attr] = value
+		}
+	}
+
+	for _, f := range fs {
+		h, isHardlinkable := f.(Hardlinkable)
+		if !isHardlinkable {
+			return nil, errNotAHardLink
+		}
+
+		if f.Mode() != prototype.Mode() {
+			return nil, fmt.Errorf("modes do not match: %v != %v", f.Mode(), prototype.Mode())
+		}
+
+		if f.UID() != prototype.UID() {
+			return nil, fmt.Errorf("uid does not match: %v != %v", f.UID(), prototype.UID())
+		}
+
+		if f.GID() != prototype.GID() {
+			return nil, fmt.Errorf("gid does not match: %v != %v", f.GID(), prototype.GID())
+		}
+
+		if xattrer, ok := f.(XAttrer); ok {
+			fxattrs := xattrer.XAttrs()
+			if !reflect.DeepEqual(fxattrs, xattrs) {
+				return nil, fmt.Errorf("resource %q xattrs do not match: %v != %v", fxattrs, xattrs)
+			}
+		}
+
+		for _, p := range h.Paths() {
+			pfs, ok := bypath[p]
+			if !ok {
+				// ensure paths are unique by only appending on a new path.
+				paths = append(paths, p)
+			}
+
+			bypath[p] = append(pfs, f)
+		}
+
+		if regFile, isRegFile := f.(RegularFile); isRegFile {
+			prototypeRegFile, prototypeIsRegFile := prototype.(RegularFile)
+			if !prototypeIsRegFile {
+				return nil, errors.New("prototype is not a regular file")
+			}
+
+			if regFile.Size() != prototypeRegFile.Size() {
+				return nil, fmt.Errorf("size does not match: %v != %v", regFile.Size(), prototypeRegFile.Size())
+			}
+
+			digests = append(digests, regFile.Digests()...)
+		} else if device, isDevice := f.(Device); isDevice {
+			prototypeDevice, prototypeIsDevice := prototype.(Device)
+			if !prototypeIsDevice {
+				return nil, errors.New("prototype is not a device")
+			}
+
+			if device.Major() != prototypeDevice.Major() {
+				return nil, fmt.Errorf("major number does not match: %v != %v", device.Major(), prototypeDevice.Major())
+			}
+			if device.Minor() != prototypeDevice.Minor() {
+				return nil, fmt.Errorf("minor number does not match: %v != %v", device.Minor(), prototypeDevice.Minor())
+			}
+		} else if _, isNamedPipe := f.(NamedPipe); isNamedPipe {
+			_, prototypeIsNamedPipe := prototype.(NamedPipe)
+			if !prototypeIsNamedPipe {
+				return nil, errors.New("prototype is not a named pipe")
+			}
+		} else {
+			return nil, errNotAHardLink
+		}
+	}
+
+	sort.Stable(sort.StringSlice(paths))
+
+	// Choose a "canonical" file. Really, it is just the first file to sort
+	// against. We also effectively select the very first digest as the
+	// "canonical" one for this file.
+	first := bypath[paths[0]][0]
+
+	resource := resource{
+		paths:  paths,
+		mode:   first.Mode(),
+		uid:    first.UID(),
+		gid:    first.GID(),
+		xattrs: xattrs,
+	}
+
+	switch typedF := first.(type) {
+	case RegularFile:
+		var err error
+		digests, err = uniqifyDigests(digests...)
+		if err != nil {
+			return nil, err
+		}
+
+		return &regularFile{
+			resource: resource,
+			size:     typedF.Size(),
+			digests:  digests,
+		}, nil
+	case Device:
+		return &device{
+			resource: resource,
+			major:    typedF.Major(),
+			minor:    typedF.Minor(),
+		}, nil
+
+	case NamedPipe:
+		return &namedPipe{
+			resource: resource,
+		}, nil
+
+	default:
+		return nil, errNotAHardLink
+	}
+}
+
+type Directory interface {
+	Resource
+	XAttrer
+
+	// Directory is a no-op method to identify directory objects by interface.
+	Directory()
+}
+
+type SymLink interface {
+	Resource
+
+	// Target returns the target of the symlink contained in the .
+	Target() string
+}
+
+type NamedPipe interface {
+	Resource
+	Hardlinkable
+	XAttrer
+
+	// Pipe is a no-op method to allow consistent resolution of NamedPipe
+	// interface.
+	Pipe()
+}
+
+type Device interface {
+	Resource
+	Hardlinkable
+	XAttrer
+
+	Major() uint64
+	Minor() uint64
+}
+
+type resource struct {
+	paths    []string
+	mode     os.FileMode
+	uid, gid string
+	xattrs   map[string][]byte
+}
+
+var _ Resource = &resource{}
+
+// newBaseResource returns a *resource, populated with data from p and fi,
+// where p will be populated directly.
+func newBaseResource(p string, mode os.FileMode, uid, gid string) (*resource, error) {
+	return &resource{
+		paths: []string{p},
+		mode:  mode,
+
+		uid: uid,
+		gid: gid,
+
+		// NOTE(stevvooe): Population of shared xattrs field is deferred to
+		// the resource types that populate it. Since they are a property of
+		// the context, they must set there.
+	}, nil
+}
+
+func (r *resource) Path() string {
+	if len(r.paths) < 1 {
+		return ""
+	}
+
+	return r.paths[0]
+}
+
+func (r *resource) Mode() os.FileMode {
+	return r.mode
+}
+
+func (r *resource) UID() string {
+	return r.uid
+}
+
+func (r *resource) GID() string {
+	return r.gid
+}
+
+type regularFile struct {
+	resource
+	size    int64
+	digests []digest.Digest
+}
+
+var _ RegularFile = &regularFile{}
+
+// newRegularFile returns the RegularFile, using the populated base resource
+// and one or more digests of the content.
+func newRegularFile(base resource, paths []string, size int64, dgsts ...digest.Digest) (RegularFile, error) {
+	if !base.Mode().IsRegular() {
+		return nil, fmt.Errorf("not a regular file")
+	}
+
+	base.paths = make([]string, len(paths))
+	copy(base.paths, paths)
+
+	// make our own copy of digests
+	ds := make([]digest.Digest, len(dgsts))
+	copy(ds, dgsts)
+
+	return &regularFile{
+		resource: base,
+		size:     size,
+		digests:  ds,
+	}, nil
+}
+
+func (rf *regularFile) Paths() []string {
+	paths := make([]string, len(rf.paths))
+	copy(paths, rf.paths)
+	return paths
+}
+
+func (rf *regularFile) Size() int64 {
+	return rf.size
+}
+
+func (rf *regularFile) Digests() []digest.Digest {
+	digests := make([]digest.Digest, len(rf.digests))
+	copy(digests, rf.digests)
+	return digests
+}
+
+func (rf *regularFile) XAttrs() map[string][]byte {
+	xattrs := make(map[string][]byte, len(rf.xattrs))
+
+	for attr, value := range rf.xattrs {
+		xattrs[attr] = append(xattrs[attr], value...)
+	}
+
+	return xattrs
+}
+
+type directory struct {
+	resource
+}
+
+var _ Directory = &directory{}
+
+func newDirectory(base resource) (Directory, error) {
+	if !base.Mode().IsDir() {
+		return nil, fmt.Errorf("not a directory")
+	}
+
+	return &directory{
+		resource: base,
+	}, nil
+}
+
+func (d *directory) Directory() {}
+
+func (d *directory) XAttrs() map[string][]byte {
+	xattrs := make(map[string][]byte, len(d.xattrs))
+
+	for attr, value := range d.xattrs {
+		xattrs[attr] = append(xattrs[attr], value...)
+	}
+
+	return xattrs
+}
+
+type symLink struct {
+	resource
+	target string
+}
+
+var _ SymLink = &symLink{}
+
+func newSymLink(base resource, target string) (SymLink, error) {
+	if base.Mode()&os.ModeSymlink == 0 {
+		return nil, fmt.Errorf("not a symlink")
+	}
+
+	return &symLink{
+		resource: base,
+		target:   target,
+	}, nil
+}
+
+func (l *symLink) Target() string {
+	return l.target
+}
+
+type namedPipe struct {
+	resource
+}
+
+var _ NamedPipe = &namedPipe{}
+
+func newNamedPipe(base resource, paths []string) (NamedPipe, error) {
+	if base.Mode()&os.ModeNamedPipe == 0 {
+		return nil, fmt.Errorf("not a namedpipe")
+	}
+
+	base.paths = make([]string, len(paths))
+	copy(base.paths, paths)
+
+	return &namedPipe{
+		resource: base,
+	}, nil
+}
+
+func (np *namedPipe) Pipe() {}
+
+func (np *namedPipe) Paths() []string {
+	paths := make([]string, len(np.paths))
+	copy(paths, np.paths)
+	return paths
+}
+
+func (np *namedPipe) XAttrs() map[string][]byte {
+	xattrs := make(map[string][]byte, len(np.xattrs))
+
+	for attr, value := range np.xattrs {
+		xattrs[attr] = append(xattrs[attr], value...)
+	}
+
+	return xattrs
+}
+
+type device struct {
+	resource
+	major, minor uint64
+}
+
+var _ Device = &device{}
+
+func newDevice(base resource, paths []string, major, minor uint64) (Device, error) {
+	if base.Mode()&os.ModeDevice == 0 {
+		return nil, fmt.Errorf("not a device")
+	}
+
+	base.paths = make([]string, len(paths))
+	copy(base.paths, paths)
+
+	return &device{
+		resource: base,
+		major:    major,
+		minor:    minor,
+	}, nil
+}
+
+func (d *device) Paths() []string {
+	paths := make([]string, len(d.paths))
+	copy(paths, d.paths)
+	return paths
+}
+
+func (d *device) XAttrs() map[string][]byte {
+	xattrs := make(map[string][]byte, len(d.xattrs))
+
+	for attr, value := range d.xattrs {
+		xattrs[attr] = append(xattrs[attr], value...)
+	}
+
+	return xattrs
+}
+
+func (d device) Major() uint64 {
+	return d.major
+}
+
+func (d device) Minor() uint64 {
+	return d.minor
+}
+
+// toProto converts a resource to a protobuf record. We'd like to push this
+// the individual types but we want to keep this all together during
+// prototyping.
+func toProto(resource Resource) *pb.Resource {
+	b := &pb.Resource{
+		Path: []string{resource.Path()},
+		Mode: uint32(resource.Mode()),
+		Uid:  resource.UID(),
+		Gid:  resource.GID(),
+	}
+
+	if xattrer, ok := resource.(XAttrer); ok {
+		b.Xattr = xattrer.XAttrs()
+	}
+
+	switch r := resource.(type) {
+	case RegularFile:
+		b.Path = r.Paths()
+		b.Size = uint64(r.Size())
+
+		for _, dgst := range r.Digests() {
+			b.Digest = append(b.Digest, dgst.String())
+		}
+	case SymLink:
+		b.Target = r.Target()
+	case Device:
+		b.Major, b.Minor = r.Major(), r.Minor()
+		b.Path = r.Paths()
+	case NamedPipe:
+		b.Path = r.Paths()
+	}
+
+	// enforce a few stability guarantees that may not be provided by the
+	// resource implementation.
+	sort.Strings(b.Path)
+
+	return b
+}
+
+// fromProto converts from a protobuf Resource to a Resource interface.
+func fromProto(b *pb.Resource) (Resource, error) {
+	base, err := newBaseResource(b.Path[0], os.FileMode(b.Mode), b.Uid, b.Gid)
+	if err != nil {
+		return nil, err
+	}
+
+	base.xattrs = make(map[string][]byte, len(b.Xattr))
+
+	for attr, value := range b.Xattr {
+		base.xattrs[attr] = append(base.xattrs[attr], value...)
+	}
+
+	switch {
+	case base.Mode().IsRegular():
+		dgsts := make([]digest.Digest, len(b.Digest))
+		for i, dgst := range b.Digest {
+			// TODO(stevvooe): Should we be validating at this point?
+			dgsts[i] = digest.Digest(dgst)
+		}
+
+		return newRegularFile(*base, b.Path, int64(b.Size), dgsts...)
+	case base.Mode().IsDir():
+		return newDirectory(*base)
+	case base.Mode()&os.ModeSymlink != 0:
+		return newSymLink(*base, b.Target)
+	case base.Mode()&os.ModeNamedPipe != 0:
+		return newNamedPipe(*base, b.Path)
+	case base.Mode()&os.ModeDevice != 0:
+		return newDevice(*base, b.Path, b.Major, b.Minor)
+	}
+
+	return nil, fmt.Errorf("unknown resource record (%#v): %s", b, base.Mode())
+}
+
+// NOTE(stevvooe): An alternative model that supports inline declaration.
+// Convenient for unit testing where inline declarations may be desirable but
+// creates an awkward API for the standard use case.
+
+// type ResourceKind int
+
+// const (
+// 	ResourceRegularFile = iota + 1
+// 	ResourceDirectory
+// 	ResourceSymLink
+// 	Resource
+// )
+
+// type Resource struct {
+// 	Kind         ResourceKind
+// 	Paths        []string
+// 	Mode         os.FileMode
+// 	UID          string
+// 	GID          string
+// 	Size         int64
+// 	Digests      []digest.Digest
+// 	Target       string
+// 	Major, Minor int
+// 	XAttrs       map[string][]byte
+// }
+
+// type RegularFile struct {
+// 	Paths   []string
+//  Size 	int64
+// 	Digests []digest.Digest
+// 	Perm    os.FileMode // os.ModePerm + sticky, setuid, setgid
+// }

vendor/github.com/stevvooe/continuity/sysx/asm.s

@@ -0,0 +1,10 @@
+// Copyright 2014 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !gccgo
+
+#include "textflag.h"
+
+TEXT ·use(SB),NOSPLIT,$0
+	RET

vendor/github.com/stevvooe/continuity/sysx/chmod_darwin.go

@@ -0,0 +1,18 @@
+package sysx
+
+const (
+	// AtSymlinkNoFollow defined from AT_SYMLINK_NOFOLLOW in <sys/fcntl.h>
+	AtSymlinkNofollow = 0x20
+)
+
+const (
+
+	// SYS_FCHMODAT defined from golang.org/sys/unix
+	SYS_FCHMODAT = 467
+)
+
+// These functions will be generated by generate.sh
+//    $ GOOS=darwin GOARCH=386 ./generate.sh chmod
+//    $ GOOS=darwin GOARCH=amd64 ./generate.sh chmod
+
+//sys  Fchmodat(dirfd int, path string, mode uint32, flags int) (err error)

vendor/github.com/stevvooe/continuity/sysx/chmod_darwin_386.go

@@ -0,0 +1,25 @@
+// mksyscall.pl -l32 chmod_darwin.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	_, _, e1 := syscall.Syscall6(SYS_FCHMODAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(mode), uintptr(flags), 0, 0)
+	use(unsafe.Pointer(_p0))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/chmod_darwin_amd64.go

@@ -0,0 +1,25 @@
+// mksyscall.pl chmod_darwin.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	_, _, e1 := syscall.Syscall6(SYS_FCHMODAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(mode), uintptr(flags), 0, 0)
+	use(unsafe.Pointer(_p0))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/chmod_linux.go

@@ -0,0 +1,12 @@
+package sysx
+
+import "syscall"
+
+const (
+	// AtSymlinkNoFollow defined from AT_SYMLINK_NOFOLLOW in /usr/include/linux/fcntl.h
+	AtSymlinkNofollow = 0x100
+)
+
+func Fchmodat(dirfd int, path string, mode uint32, flags int) error {
+	return syscall.Fchmodat(dirfd, path, mode, flags)
+}

vendor/github.com/stevvooe/continuity/sysx/copy_linux.go

@@ -0,0 +1,9 @@
+package sysx
+
+// These functions will be generated by generate.sh
+//    $ GOOS=linux GOARCH=386 ./generate.sh copy
+//    $ GOOS=linux GOARCH=amd64 ./generate.sh copy
+//    $ GOOS=linux GOARCH=arm ./generate.sh copy
+//    $ GOOS=linux GOARCH=arm64 ./generate.sh copy
+
+//sys CopyFileRange(fdin uintptr, offin *int64, fdout uintptr, offout *int64, len int, flags int) (n int, err error)

vendor/github.com/stevvooe/continuity/sysx/copy_linux_386.go

@@ -0,0 +1,20 @@
+// mksyscall.pl -l32 copy_linux.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func CopyFileRange(fdin uintptr, offin *int64, fdout uintptr, offout *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := syscall.Syscall6(SYS_COPY_FILE_RANGE, uintptr(fdin), uintptr(unsafe.Pointer(offin)), uintptr(fdout), uintptr(unsafe.Pointer(offout)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/copy_linux_amd64.go

@@ -0,0 +1,20 @@
+// mksyscall.pl copy_linux.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func CopyFileRange(fdin uintptr, offin *int64, fdout uintptr, offout *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := syscall.Syscall6(SYS_COPY_FILE_RANGE, uintptr(fdin), uintptr(unsafe.Pointer(offin)), uintptr(fdout), uintptr(unsafe.Pointer(offout)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/copy_linux_arm64.go

@@ -0,0 +1,20 @@
+// mksyscall.pl copy_linux.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func CopyFileRange(fdin uintptr, offin *int64, fdout uintptr, offout *int64, len int, flags int) (n int, err error) {
+	r0, _, e1 := syscall.Syscall6(SYS_COPY_FILE_RANGE, uintptr(fdin), uintptr(unsafe.Pointer(offin)), uintptr(fdout), uintptr(unsafe.Pointer(offout)), uintptr(len), uintptr(flags))
+	n = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/sys.go

@@ -0,0 +1,37 @@
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+var _zero uintptr
+
+// use is a no-op, but the compiler cannot see that it is.
+// Calling use(p) ensures that p is kept live until that point.
+//go:noescape
+func use(p unsafe.Pointer)
+
+// Do the interface allocations only once for common
+// Errno values.
+var (
+	errEAGAIN error = syscall.EAGAIN
+	errEINVAL error = syscall.EINVAL
+	errENOENT error = syscall.ENOENT
+)
+
+// errnoErr returns common boxed Errno values, to prevent
+// allocations at runtime.
+func errnoErr(e syscall.Errno) error {
+	switch e {
+	case 0:
+		return nil
+	case syscall.EAGAIN:
+		return errEAGAIN
+	case syscall.EINVAL:
+		return errEINVAL
+	case syscall.ENOENT:
+		return errENOENT
+	}
+	return e
+}

vendor/github.com/stevvooe/continuity/sysx/sysnum_linux_386.go

@@ -0,0 +1,7 @@
+package sysx
+
+const (
+	// SYS_COPYFILERANGE defined in Kernel 4.5+
+	// Number defined in /usr/include/asm/unistd_32.h
+	SYS_COPY_FILE_RANGE = 377
+)

vendor/github.com/stevvooe/continuity/sysx/sysnum_linux_amd64.go

@@ -0,0 +1,7 @@
+package sysx
+
+const (
+	// SYS_COPYFILERANGE defined in Kernel 4.5+
+	// Number defined in /usr/include/asm/unistd_64.h
+	SYS_COPY_FILE_RANGE = 326
+)

vendor/github.com/stevvooe/continuity/sysx/sysnum_linux_arm64.go

@@ -0,0 +1,7 @@
+package sysx
+
+const (
+	// SYS_COPY_FILE_RANGE defined in Kernel 4.5+
+	// Number defined in /usr/include/asm-generic/unistd.h
+	SYS_COPY_FILE_RANGE = 285
+)

vendor/github.com/stevvooe/continuity/sysx/xattr.go

@@ -0,0 +1,64 @@
+package sysx
+
+import (
+	"bytes"
+	"syscall"
+)
+
+const defaultXattrBufferSize = 5
+
+type listxattrFunc func(path string, dest []byte) (int, error)
+
+func listxattrAll(path string, listFunc listxattrFunc) ([]string, error) {
+	var p []byte // nil on first execution
+
+	for {
+		n, err := listFunc(path, p) // first call gets buffer size.
+		if err != nil {
+			return nil, err
+		}
+
+		if n > len(p) {
+			p = make([]byte, n)
+			continue
+		}
+
+		p = p[:n]
+
+		ps := bytes.Split(bytes.TrimSuffix(p, []byte{0}), []byte{0})
+		var entries []string
+		for _, p := range ps {
+			s := string(p)
+			if s != "" {
+				entries = append(entries, s)
+			}
+		}
+
+		return entries, nil
+	}
+}
+
+type getxattrFunc func(string, string, []byte) (int, error)
+
+func getxattrAll(path, attr string, getFunc getxattrFunc) ([]byte, error) {
+	p := make([]byte, defaultXattrBufferSize)
+	for {
+		n, err := getFunc(path, attr, p)
+		if err != nil {
+			if errno, ok := err.(syscall.Errno); ok && errno == syscall.ERANGE {
+				p = make([]byte, len(p)*2) // this can't be ideal.
+				continue                   // try again!
+			}
+
+			return nil, err
+		}
+
+		// realloc to correct size and repeat
+		if n > len(p) {
+			p = make([]byte, n)
+			continue
+		}
+
+		return p[:n], nil
+	}
+}

vendor/github.com/stevvooe/continuity/sysx/xattr_darwin.go

@@ -0,0 +1,71 @@
+package sysx
+
+// These functions will be generated by generate.sh
+//    $ GOOS=darwin GOARCH=386 ./generate.sh xattr
+//    $ GOOS=darwin GOARCH=amd64 ./generate.sh xattr
+
+//sys  getxattr(path string, attr string, dest []byte, pos int, options int) (sz int, err error)
+//sys  setxattr(path string, attr string, data []byte, flags int) (err error)
+//sys  removexattr(path string, attr string, options int) (err error)
+//sys  listxattr(path string, dest []byte, options int) (sz int, err error)
+//sys  Fchmodat(dirfd int, path string, mode uint32, flags int) (err error)
+
+const (
+	xattrNoFollow = 0x01
+)
+
+func listxattrFollow(path string, dest []byte) (sz int, err error) {
+	return listxattr(path, dest, 0)
+}
+
+// Listxattr calls syscall getxattr
+func Listxattr(path string) ([]string, error) {
+	return listxattrAll(path, listxattrFollow)
+}
+
+// Removexattr calls syscall getxattr
+func Removexattr(path string, attr string) (err error) {
+	return removexattr(path, attr, 0)
+}
+
+// Setxattr calls syscall setxattr
+func Setxattr(path string, attr string, data []byte, flags int) (err error) {
+	return setxattr(path, attr, data, flags)
+}
+
+func getxattrFollow(path, attr string, dest []byte) (sz int, err error) {
+	return getxattr(path, attr, dest, 0, 0)
+}
+
+// Getxattr calls syscall getxattr
+func Getxattr(path, attr string) ([]byte, error) {
+	return getxattrAll(path, attr, getxattrFollow)
+}
+
+func listxattrNoFollow(path string, dest []byte) (sz int, err error) {
+	return listxattr(path, dest, xattrNoFollow)
+}
+
+// LListxattr calls syscall listxattr with XATTR_NOFOLLOW
+func LListxattr(path string) ([]string, error) {
+	return listxattrAll(path, listxattrNoFollow)
+}
+
+// LRemovexattr calls syscall removexattr with XATTR_NOFOLLOW
+func LRemovexattr(path string, attr string) (err error) {
+	return removexattr(path, attr, xattrNoFollow)
+}
+
+// Setxattr calls syscall setxattr with XATTR_NOFOLLOW
+func LSetxattr(path string, attr string, data []byte, flags int) (err error) {
+	return setxattr(path, attr, data, flags|xattrNoFollow)
+}
+
+func getxattrNoFollow(path, attr string, dest []byte) (sz int, err error) {
+	return getxattr(path, attr, dest, 0, xattrNoFollow)
+}
+
+// LGetxattr calls syscall getxattr with XATTR_NOFOLLOW
+func LGetxattr(path, attr string) ([]byte, error) {
+	return getxattrAll(path, attr, getxattrNoFollow)
+}

vendor/github.com/stevvooe/continuity/sysx/xattr_darwin_386.go

@@ -0,0 +1,111 @@
+// mksyscall.pl -l32 xattr_darwin.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func getxattr(path string, attr string, dest []byte, pos int, options int) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(dest) > 0 {
+		_p2 = unsafe.Pointer(&dest[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_GETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(dest)), uintptr(pos), uintptr(options))
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func setxattr(path string, attr string, data []byte, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(data) > 0 {
+		_p2 = unsafe.Pointer(&data[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	_, _, e1 := syscall.Syscall6(syscall.SYS_SETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(data)), uintptr(flags), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func removexattr(path string, attr string, options int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	_, _, e1 := syscall.Syscall(syscall.SYS_REMOVEXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(options))
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func listxattr(path string, dest []byte, options int) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 unsafe.Pointer
+	if len(dest) > 0 {
+		_p1 = unsafe.Pointer(&dest[0])
+	} else {
+		_p1 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_LISTXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(_p1), uintptr(len(dest)), uintptr(options), 0, 0)
+	use(unsafe.Pointer(_p0))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/xattr_darwin_amd64.go

@@ -0,0 +1,111 @@
+// mksyscall.pl xattr_darwin.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func getxattr(path string, attr string, dest []byte, pos int, options int) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(dest) > 0 {
+		_p2 = unsafe.Pointer(&dest[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_GETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(dest)), uintptr(pos), uintptr(options))
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func setxattr(path string, attr string, data []byte, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(data) > 0 {
+		_p2 = unsafe.Pointer(&data[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	_, _, e1 := syscall.Syscall6(syscall.SYS_SETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(data)), uintptr(flags), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func removexattr(path string, attr string, options int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	_, _, e1 := syscall.Syscall(syscall.SYS_REMOVEXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(options))
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func listxattr(path string, dest []byte, options int) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 unsafe.Pointer
+	if len(dest) > 0 {
+		_p1 = unsafe.Pointer(&dest[0])
+	} else {
+		_p1 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_LISTXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(_p1), uintptr(len(dest)), uintptr(options), 0, 0)
+	use(unsafe.Pointer(_p0))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/xattr_linux.go

@@ -0,0 +1,58 @@
+package sysx
+
+import "syscall"
+
+// These functions will be generated by generate.sh
+//    $ GOOS=linux GOARCH=386 ./generate.sh xattr
+//    $ GOOS=linux GOARCH=amd64 ./generate.sh xattr
+//    $ GOOS=linux GOARCH=arm ./generate.sh xattr
+//    $ GOOS=linux GOARCH=arm64 ./generate.sh xattr
+
+// Listxattr calls syscall listxattr and reads all content
+// and returns a string array
+func Listxattr(path string) ([]string, error) {
+	return listxattrAll(path, syscall.Listxattr)
+}
+
+// Removexattr calls syscall removexattr
+func Removexattr(path string, attr string) (err error) {
+	return syscall.Removexattr(path, attr)
+}
+
+// Setxattr calls syscall setxattr
+func Setxattr(path string, attr string, data []byte, flags int) (err error) {
+	return syscall.Setxattr(path, attr, data, flags)
+}
+
+// Getxattr calls syscall getxattr
+func Getxattr(path, attr string) ([]byte, error) {
+	return getxattrAll(path, attr, syscall.Getxattr)
+}
+
+//sys llistxattr(path string, dest []byte) (sz int, err error)
+
+// LListxattr lists xattrs, not following symlinks
+func LListxattr(path string) ([]string, error) {
+	return listxattrAll(path, llistxattr)
+}
+
+//sys lremovexattr(path string, attr string) (err error)
+
+// LRemovexattr removes an xattr, not following symlinks
+func LRemovexattr(path string, attr string) (err error) {
+	return lremovexattr(path, attr)
+}
+
+//sys lsetxattr(path string, attr string, data []byte, flags int) (err error)
+
+// LSetxattr sets an xattr, not following symlinks
+func LSetxattr(path string, attr string, data []byte, flags int) (err error) {
+	return lsetxattr(path, attr, data, flags)
+}
+
+//sys lgetxattr(path string, attr string, dest []byte) (sz int, err error)
+
+// LGetxattr gets an xattr, not following symlinks
+func LGetxattr(path, attr string) ([]byte, error) {
+	return getxattrAll(path, attr, lgetxattr)
+}

vendor/github.com/stevvooe/continuity/sysx/xattr_linux_386.go

@@ -0,0 +1,111 @@
+// mksyscall.pl -l32 xattr_linux.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func llistxattr(path string, dest []byte) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 unsafe.Pointer
+	if len(dest) > 0 {
+		_p1 = unsafe.Pointer(&dest[0])
+	} else {
+		_p1 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall(syscall.SYS_LLISTXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(_p1), uintptr(len(dest)))
+	use(unsafe.Pointer(_p0))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lremovexattr(path string, attr string) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	_, _, e1 := syscall.Syscall(syscall.SYS_LREMOVEXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lsetxattr(path string, attr string, data []byte, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(data) > 0 {
+		_p2 = unsafe.Pointer(&data[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	_, _, e1 := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(data)), uintptr(flags), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lgetxattr(path string, attr string, dest []byte) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(dest) > 0 {
+		_p2 = unsafe.Pointer(&dest[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(dest)), 0, 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/xattr_linux_amd64.go

@@ -0,0 +1,111 @@
+// mksyscall.pl xattr_linux.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func llistxattr(path string, dest []byte) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 unsafe.Pointer
+	if len(dest) > 0 {
+		_p1 = unsafe.Pointer(&dest[0])
+	} else {
+		_p1 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall(syscall.SYS_LLISTXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(_p1), uintptr(len(dest)))
+	use(unsafe.Pointer(_p0))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lremovexattr(path string, attr string) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	_, _, e1 := syscall.Syscall(syscall.SYS_LREMOVEXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lsetxattr(path string, attr string, data []byte, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(data) > 0 {
+		_p2 = unsafe.Pointer(&data[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	_, _, e1 := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(data)), uintptr(flags), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lgetxattr(path string, attr string, dest []byte) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(dest) > 0 {
+		_p2 = unsafe.Pointer(&dest[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(dest)), 0, 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/xattr_linux_arm.go

@@ -0,0 +1,111 @@
+// mksyscall.pl -l32 xattr_linux.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func llistxattr(path string, dest []byte) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 unsafe.Pointer
+	if len(dest) > 0 {
+		_p1 = unsafe.Pointer(&dest[0])
+	} else {
+		_p1 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall(syscall.SYS_LLISTXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(_p1), uintptr(len(dest)))
+	use(unsafe.Pointer(_p0))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lremovexattr(path string, attr string) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	_, _, e1 := syscall.Syscall(syscall.SYS_LREMOVEXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lsetxattr(path string, attr string, data []byte, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(data) > 0 {
+		_p2 = unsafe.Pointer(&data[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	_, _, e1 := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(data)), uintptr(flags), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lgetxattr(path string, attr string, dest []byte) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(dest) > 0 {
+		_p2 = unsafe.Pointer(&dest[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(dest)), 0, 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/github.com/stevvooe/continuity/sysx/xattr_linux_arm64.go

@@ -0,0 +1,111 @@
+// mksyscall.pl xattr_linux.go
+// MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+
+package sysx
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func llistxattr(path string, dest []byte) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 unsafe.Pointer
+	if len(dest) > 0 {
+		_p1 = unsafe.Pointer(&dest[0])
+	} else {
+		_p1 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall(syscall.SYS_LLISTXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(_p1), uintptr(len(dest)))
+	use(unsafe.Pointer(_p0))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lremovexattr(path string, attr string) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	_, _, e1 := syscall.Syscall(syscall.SYS_LREMOVEXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lsetxattr(path string, attr string, data []byte, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(data) > 0 {
+		_p2 = unsafe.Pointer(&data[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	_, _, e1 := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(data)), uintptr(flags), 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func lgetxattr(path string, attr string, dest []byte) (sz int, err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	var _p1 *byte
+	_p1, err = syscall.BytePtrFromString(attr)
+	if err != nil {
+		return
+	}
+	var _p2 unsafe.Pointer
+	if len(dest) > 0 {
+		_p2 = unsafe.Pointer(&dest[0])
+	} else {
+		_p2 = unsafe.Pointer(&_zero)
+	}
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(dest)), 0, 0)
+	use(unsafe.Pointer(_p0))
+	use(unsafe.Pointer(_p1))
+	sz = int(r0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

vendor/golang.org/x/sync/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/golang.org/x/sync/PATENTS

@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.

vendor/golang.org/x/sync/errgroup/errgroup.go

@@ -0,0 +1,67 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package errgroup provides synchronization, error propagation, and Context
+// cancelation for groups of goroutines working on subtasks of a common task.
+package errgroup
+
+import (
+	"sync"
+
+	"golang.org/x/net/context"
+)
+
+// A Group is a collection of goroutines working on subtasks that are part of
+// the same overall task.
+//
+// A zero Group is valid and does not cancel on error.
+type Group struct {
+	cancel func()
+
+	wg sync.WaitGroup
+
+	errOnce sync.Once
+	err     error
+}
+
+// WithContext returns a new Group and an associated Context derived from ctx.
+//
+// The derived Context is canceled the first time a function passed to Go
+// returns a non-nil error or the first time Wait returns, whichever occurs
+// first.
+func WithContext(ctx context.Context) (*Group, context.Context) {
+	ctx, cancel := context.WithCancel(ctx)
+	return &Group{cancel: cancel}, ctx
+}
+
+// Wait blocks until all function calls from the Go method have returned, then
+// returns the first non-nil error (if any) from them.
+func (g *Group) Wait() error {
+	g.wg.Wait()
+	if g.cancel != nil {
+		g.cancel()
+	}
+	return g.err
+}
+
+// Go calls the given function in a new goroutine.
+//
+// The first call to return a non-nil error cancels the group; its error will be
+// returned by Wait.
+func (g *Group) Go(f func() error) {
+	g.wg.Add(1)
+
+	go func() {
+		defer g.wg.Done()
+
+		if err := f(); err != nil {
+			g.errOnce.Do(func() {
+				g.err = err
+				if g.cancel != nil {
+					g.cancel()
+				}
+			})
+		}
+	}()
+}