Updated vendor for exported BuildArgs

vendor/github.com/containerd/continuity/devices/devices.go

@@ -0,0 +1,5 @@
+package devices
+
+import "fmt"
+
+var ErrNotSupported = fmt.Errorf("not supported")

vendor/github.com/containerd/continuity/devices/devices_unix.go

@@ -0,0 +1,58 @@
+// +build linux darwin freebsd solaris
+
+package devices
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+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")
+	}
+
+	dev := uint64(sys.Rdev)
+	return uint64(unix.Major(dev)), uint64(unix.Minor(dev)), 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 uint64
+	)
+
+	if mode&os.ModeDevice != 0 {
+		dev = unix.Mkdev(uint32(maj), uint32(min))
+
+		if mode&os.ModeCharDevice != 0 {
+			m |= unix.S_IFCHR
+		} else {
+			m |= unix.S_IFBLK
+		}
+	} else if mode&os.ModeNamedPipe != 0 {
+		m |= unix.S_IFIFO
+	}
+
+	return unix.Mknod(p, m, int(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 |= unix.S_ISUID
+	}
+	if i&os.ModeSetgid != 0 {
+		o |= unix.S_ISGID
+	}
+	if i&os.ModeSticky != 0 {
+		o |= unix.S_ISVTX
+	}
+	return
+}

vendor/github.com/containerd/continuity/devices/devices_windows.go

@@ -0,0 +1,11 @@
+package devices
+
+import (
+	"os"
+
+	"github.com/pkg/errors"
+)
+
+func DeviceInfo(fi os.FileInfo) (uint64, uint64, error) {
+	return 0, 0, errors.Wrap(ErrNotSupported, "cannot get device info on windows")
+}

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

@@ -0,0 +1,162 @@
+package driver
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+var ErrNotSupported = fmt.Errorf("not supported")
+
+// 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 {
+	// Note that Open() returns a File interface instead of *os.File. This
+	// is because os.File is a struct, so if Open was to return *os.File,
+	// the only way to fulfill the interface would be to call os.Open()
+	Open(path string) (File, error)
+	OpenFile(path string, flag int, perm os.FileMode) (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 string, uid, gid int64) error
+	Symlink(oldname, newname string) error
+
+	MkdirAll(path string, perm os.FileMode) error
+	RemoveAll(path 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
+}
+
+// File is the interface for interacting with files returned by continuity's Open
+// This is needed since os.File is a struct, instead of an interface, so it can't
+// be used.
+type File interface {
+	io.ReadWriteCloser
+	io.Seeker
+	Readdir(n int) ([]os.FileInfo, 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 _ File = &os.File{}
+
+// LocalDriver is the exported Driver struct for convenience.
+var LocalDriver Driver = &driver{}
+
+func (d *driver) Open(p string) (File, error) {
+	return os.Open(p)
+}
+
+func (d *driver) OpenFile(path string, flag int, perm os.FileMode) (File, error) {
+	return os.OpenFile(path, flag, perm)
+}
+
+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 string, uid, gid int64) error {
+	// TODO: error out if uid excesses int bit width?
+	return os.Lchown(name, int(uid), int(gid))
+}
+
+func (d *driver) Symlink(oldname, newname string) error {
+	return os.Symlink(oldname, newname)
+}
+
+func (d *driver) MkdirAll(path string, perm os.FileMode) error {
+	return os.MkdirAll(path, perm)
+}
+
+func (d *driver) RemoveAll(path string) error {
+	return os.RemoveAll(path)
+}

vendor/github.com/containerd/continuity/driver/driver_unix.go

@@ -0,0 +1,122 @@
+// +build linux darwin freebsd solaris
+
+package driver
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+
+	"github.com/containerd/continuity/devices"
+	"github.com/containerd/continuity/sysx"
+)
+
+func (d *driver) Mknod(path string, mode os.FileMode, major, minor int) error {
+	return devices.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 devices.Mknod(path, mode, 0, 0)
+}
+
+// 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 devices.DeviceInfo(fi)
+}

vendor/github.com/containerd/continuity/driver/driver_windows.go

@@ -0,0 +1,21 @@
+package driver
+
+import (
+	"os"
+
+	"github.com/pkg/errors"
+)
+
+func (d *driver) Mknod(path string, mode os.FileMode, major, minor int) error {
+	return errors.Wrap(ErrNotSupported, "cannot create device node on Windows")
+}
+
+func (d *driver) Mkfifo(path string, mode os.FileMode) error {
+	return errors.Wrap(ErrNotSupported, "cannot create fifo on Windows")
+}
+
+// Lchmod changes the mode of an file not following symlinks.
+func (d *driver) Lchmod(path string, mode os.FileMode) (err error) {
+	// TODO: Use Window's equivalent
+	return os.Chmod(path, mode)
+}

vendor/github.com/containerd/continuity/driver/utils.go

@@ -0,0 +1,74 @@
+package driver
+
+import (
+	"io"
+	"io/ioutil"
+	"os"
+	"sort"
+)
+
+// ReadFile works the same as ioutil.ReadFile with the Driver abstraction
+func ReadFile(r Driver, filename string) ([]byte, error) {
+	f, err := r.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	data, err := ioutil.ReadAll(f)
+	if err != nil {
+		return nil, err
+	}
+
+	return data, nil
+}
+
+// WriteFile works the same as ioutil.WriteFile with the Driver abstraction
+func WriteFile(r Driver, filename string, data []byte, perm os.FileMode) error {
+	f, err := r.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	n, err := f.Write(data)
+	if err != nil {
+		return err
+	} else if n != len(data) {
+		return io.ErrShortWrite
+	}
+
+	return nil
+}
+
+// ReadDir works the same as ioutil.ReadDir with the Driver abstraction
+func ReadDir(r Driver, dirname string) ([]os.FileInfo, error) {
+	f, err := r.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	dirs, err := f.Readdir(-1)
+	if err != nil {
+		return nil, err
+	}
+
+	sort.Sort(fileInfos(dirs))
+	return dirs, nil
+}
+
+// Simple implementation of the sort.Interface for os.FileInfo
+type fileInfos []os.FileInfo
+
+func (fis fileInfos) Len() int {
+	return len(fis)
+}
+
+func (fis fileInfos) Less(i, j int) bool {
+	return fis[i].Name() < fis[j].Name()
+}
+
+func (fis fileInfos) Swap(i, j int) {
+	fis[i], fis[j] = fis[j], fis[i]
+}

vendor/github.com/containerd/continuity/fs/copy.go

@@ -0,0 +1,121 @@
+package fs
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"github.com/pkg/errors"
+)
+
+var bufferPool = &sync.Pool{
+	New: func() interface{} {
+		buffer := make([]byte, 32*1024)
+		return &buffer
+	},
+}
+
+// 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(target, source); 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
+}
+
+// CopyFile copies the source file to the target.
+// The most efficient means of copying is used for the platform.
+func CopyFile(target, source string) error {
+	src, err := os.Open(source)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open source %s", source)
+	}
+	defer src.Close()
+	tgt, err := os.Create(target)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open target %s", target)
+	}
+	defer tgt.Close()
+
+	return copyFileContent(tgt, src)
+}

vendor/github.com/containerd/continuity/fs/copy_linux.go

@@ -0,0 +1,95 @@
+package fs
+
+import (
+	"io"
+	"os"
+	"syscall"
+
+	"github.com/containerd/continuity/sysx"
+	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
+)
+
+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 {
+		if os.IsPermission(err) {
+			// Normally if uid/gid are the same this would be a no-op, but some
+			// filesystems may still return EPERM... for instance NFS does this.
+			// In such a case, this is not an error.
+			if dstStat, err2 := os.Lstat(name); err2 == nil {
+				st2 := dstStat.Sys().(*syscall.Stat_t)
+				if st.Uid == st2.Uid && st.Gid == st2.Gid {
+					err = nil
+				}
+			}
+		}
+		if 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)
+		}
+	}
+
+	timespec := []unix.Timespec{unix.Timespec(StatAtime(st)), unix.Timespec(StatMtime(st))}
+	if err := unix.UtimesNanoAt(unix.AT_FDCWD, name, timespec, unix.AT_SYMLINK_NOFOLLOW); 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 := unix.CopyFileRange(int(src.Fd()), nil, int(dst.Fd()), nil, int(st.Size()), 0)
+	if err != nil {
+		if err != unix.ENOSYS && err != unix.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 unix.Mknod(dst, uint32(fi.Mode()), int(st.Rdev))
+}

vendor/github.com/containerd/continuity/fs/copy_unix.go

@@ -0,0 +1,80 @@
+// +build solaris darwin freebsd
+
+package fs
+
+import (
+	"io"
+	"os"
+	"syscall"
+
+	"github.com/containerd/continuity/sysx"
+	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
+)
+
+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 {
+		if os.IsPermission(err) {
+			// Normally if uid/gid are the same this would be a no-op, but some
+			// filesystems may still return EPERM... for instance NFS does this.
+			// In such a case, this is not an error.
+			if dstStat, err2 := os.Lstat(name); err2 == nil {
+				st2 := dstStat.Sys().(*syscall.Stat_t)
+				if st.Uid == st2.Uid && st.Gid == st2.Gid {
+					err = nil
+				}
+			}
+		}
+		if 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)
+		}
+	}
+
+	timespec := []syscall.Timespec{StatAtime(st), StatMtime(st)}
+	if err := syscall.UtimesNano(name, timespec); err != nil {
+		return errors.Wrapf(err, "failed to utime %s", name)
+	}
+
+	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 {
+	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 unix.Mknod(dst, uint32(fi.Mode()), int(st.Rdev))
+}

vendor/github.com/containerd/continuity/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")
+}

vendor/github.com/containerd/continuity/fs/diff.go

@@ -0,0 +1,310 @@
+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 (
+	// ChangeKindUnmodified represents an unmodified
+	// file
+	ChangeKindUnmodified = iota
+
+	// ChangeKindAdd represents an addition of
+	// a file
+	ChangeKindAdd
+
+	// 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 ChangeKindUnmodified:
+		return "unmodified"
+	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 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 {
+					if !isLinked(f) {
+						continue
+					}
+					k = ChangeKindUnmodified
+				}
+			}
+			if err := changeFn(k, p, f, nil); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+
+	return g.Wait()
+}

vendor/github.com/containerd/continuity/fs/diff_unix.go

@@ -0,0 +1,58 @@
+// +build !windows
+
+package fs
+
+import (
+	"bytes"
+	"os"
+	"syscall"
+
+	"github.com/containerd/continuity/sysx"
+	"github.com/pkg/errors"
+)
+
+// 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
+}
+
+// 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 != sysx.ENODATA {
+		return false, errors.Wrapf(err, "failed to get xattr for %s", p1)
+	}
+	c2, err := sysx.LGetxattr(p2, "security.capability")
+	if err != nil && err != sysx.ENODATA {
+		return false, errors.Wrapf(err, "failed to get xattr for %s", p2)
+	}
+	return bytes.Equal(c1, c2), nil
+}
+
+func isLinked(f os.FileInfo) bool {
+	s, ok := f.Sys().(*syscall.Stat_t)
+	if !ok {
+		return false
+	}
+	return !f.IsDir() && s.Nlink > 1
+}

vendor/github.com/containerd/continuity/fs/diff_windows.go

@@ -0,0 +1,32 @@
+package fs
+
+import (
+	"os"
+
+	"golang.org/x/sys/windows"
+)
+
+func detectDirDiff(upper, lower string) *diffDirOptions {
+	return nil
+}
+
+func compareSysStat(s1, s2 interface{}) (bool, error) {
+	f1, ok := s1.(windows.Win32FileAttributeData)
+	if !ok {
+		return false, nil
+	}
+	f2, ok := s2.(windows.Win32FileAttributeData)
+	if !ok {
+		return false, nil
+	}
+	return f1.FileAttributes == f2.FileAttributes, nil
+}
+
+func compareCapabilities(p1, p2 string) (bool, error) {
+	// TODO: Use windows equivalent
+	return true, nil
+}
+
+func isLinked(os.FileInfo) bool {
+	return false
+}

vendor/github.com/containerd/continuity/fs/dtype_linux.go

@@ -0,0 +1,87 @@
+// +build linux
+
+package fs
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+func locateDummyIfEmpty(path string) (string, error) {
+	children, err := ioutil.ReadDir(path)
+	if err != nil {
+		return "", err
+	}
+	if len(children) != 0 {
+		return "", nil
+	}
+	dummyFile, err := ioutil.TempFile(path, "fsutils-dummy")
+	if err != nil {
+		return "", err
+	}
+	name := dummyFile.Name()
+	err = dummyFile.Close()
+	return name, err
+}
+
+// SupportsDType returns whether the filesystem mounted on path supports d_type
+func SupportsDType(path string) (bool, error) {
+	// locate dummy so that we have at least one dirent
+	dummy, err := locateDummyIfEmpty(path)
+	if err != nil {
+		return false, err
+	}
+	if dummy != "" {
+		defer os.Remove(dummy)
+	}
+
+	visited := 0
+	supportsDType := true
+	fn := func(ent *syscall.Dirent) bool {
+		visited++
+		if ent.Type == syscall.DT_UNKNOWN {
+			supportsDType = false
+			// stop iteration
+			return true
+		}
+		// continue iteration
+		return false
+	}
+	if err = iterateReadDir(path, fn); err != nil {
+		return false, err
+	}
+	if visited == 0 {
+		return false, fmt.Errorf("did not hit any dirent during iteration %s", path)
+	}
+	return supportsDType, nil
+}
+
+func iterateReadDir(path string, fn func(*syscall.Dirent) bool) error {
+	d, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer d.Close()
+	fd := int(d.Fd())
+	buf := make([]byte, 4096)
+	for {
+		nbytes, err := syscall.ReadDirent(fd, buf)
+		if err != nil {
+			return err
+		}
+		if nbytes == 0 {
+			break
+		}
+		for off := 0; off < nbytes; {
+			ent := (*syscall.Dirent)(unsafe.Pointer(&buf[off]))
+			if stop := fn(ent); stop {
+				return nil
+			}
+			off += int(ent.Reclen)
+		}
+	}
+	return nil
+}

vendor/github.com/containerd/continuity/fs/du.go

@@ -0,0 +1,22 @@
+package fs
+
+import "context"
+
+// Usage of disk information
+type Usage struct {
+	Inodes int64
+	Size   int64
+}
+
+// DiskUsage counts the number of inodes and disk usage for the resources under
+// path.
+func DiskUsage(roots ...string) (Usage, error) {
+	return diskUsage(roots...)
+}
+
+// DiffUsage counts the numbers of inodes and disk usage in the
+// diff between the 2 directories. The first path is intended
+// as the base directory and the second as the changed directory.
+func DiffUsage(ctx context.Context, a, b string) (Usage, error) {
+	return diffUsage(ctx, a, b)
+}

vendor/github.com/containerd/continuity/fs/du_unix.go

@@ -0,0 +1,88 @@
+// +build !windows
+
+package fs
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"syscall"
+)
+
+type inode struct {
+	// TODO(stevvooe): Can probably reduce memory usage by not tracking
+	// device, but we can leave this right for now.
+	dev, ino uint64
+}
+
+func newInode(stat *syscall.Stat_t) inode {
+	return inode{
+		// Dev is uint32 on darwin/bsd, uint64 on linux/solaris
+		dev: uint64(stat.Dev), // nolint: unconvert
+		// Ino is uint32 on bsd, uint64 on darwin/linux/solaris
+		ino: uint64(stat.Ino), // nolint: unconvert
+	}
+}
+
+func diskUsage(roots ...string) (Usage, error) {
+
+	var (
+		size   int64
+		inodes = map[inode]struct{}{} // expensive!
+	)
+
+	for _, root := range roots {
+		if err := filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+
+			inoKey := newInode(fi.Sys().(*syscall.Stat_t))
+			if _, ok := inodes[inoKey]; !ok {
+				inodes[inoKey] = struct{}{}
+				size += fi.Size()
+			}
+
+			return nil
+		}); err != nil {
+			return Usage{}, err
+		}
+	}
+
+	return Usage{
+		Inodes: int64(len(inodes)),
+		Size:   size,
+	}, nil
+}
+
+func diffUsage(ctx context.Context, a, b string) (Usage, error) {
+	var (
+		size   int64
+		inodes = map[inode]struct{}{} // expensive!
+	)
+
+	if err := Changes(ctx, a, b, func(kind ChangeKind, _ string, fi os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if kind == ChangeKindAdd || kind == ChangeKindModify {
+			inoKey := newInode(fi.Sys().(*syscall.Stat_t))
+			if _, ok := inodes[inoKey]; !ok {
+				inodes[inoKey] = struct{}{}
+				size += fi.Size()
+			}
+
+			return nil
+
+		}
+		return nil
+	}); err != nil {
+		return Usage{}, err
+	}
+
+	return Usage{
+		Inodes: int64(len(inodes)),
+		Size:   size,
+	}, nil
+}

vendor/github.com/containerd/continuity/fs/du_windows.go

@@ -0,0 +1,60 @@
+// +build windows
+
+package fs
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+)
+
+func diskUsage(roots ...string) (Usage, error) {
+	var (
+		size int64
+	)
+
+	// TODO(stevvooe): Support inodes (or equivalent) for windows.
+
+	for _, root := range roots {
+		if err := filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+
+			size += fi.Size()
+			return nil
+		}); err != nil {
+			return Usage{}, err
+		}
+	}
+
+	return Usage{
+		Size: size,
+	}, nil
+}
+
+func diffUsage(ctx context.Context, a, b string) (Usage, error) {
+	var (
+		size int64
+	)
+
+	if err := Changes(ctx, a, b, func(kind ChangeKind, _ string, fi os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if kind == ChangeKindAdd || kind == ChangeKindModify {
+			size += fi.Size()
+
+			return nil
+
+		}
+		return nil
+	}); err != nil {
+		return Usage{}, err
+	}
+
+	return Usage{
+		Size: size,
+	}, nil
+}

vendor/github.com/containerd/continuity/fs/hardlink.go

@@ -0,0 +1,27 @@
+package fs
+
+import "os"
+
+// GetLinkInfo returns an identifier representing the node a hardlink is pointing
+// to. If the file is not hard linked then 0 will be returned.
+func GetLinkInfo(fi os.FileInfo) (uint64, bool) {
+	return getLinkInfo(fi)
+}
+
+// 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) {
+	inode, isHardlink := getLinkInfo(fi)
+	if !isHardlink {
+		return "", nil
+	}
+
+	path, ok := inodes[inode]
+	if !ok {
+		inodes[inode] = name
+	}
+	return path, nil
+}

vendor/github.com/containerd/continuity/fs/hardlink_unix.go

@@ -0,0 +1,18 @@
+// +build !windows
+
+package fs
+
+import (
+	"os"
+	"syscall"
+)
+
+func getLinkInfo(fi os.FileInfo) (uint64, bool) {
+	s, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return 0, false
+	}
+
+	// Ino is uint32 on bsd, uint64 on darwin/linux/solaris
+	return uint64(s.Ino), !fi.IsDir() && s.Nlink > 1 // nolint: unconvert
+}

vendor/github.com/containerd/continuity/fs/hardlink_windows.go

@@ -0,0 +1,7 @@
+package fs
+
+import "os"
+
+func getLinkInfo(fi os.FileInfo) (uint64, bool) {
+	return 0, false
+}

vendor/github.com/containerd/continuity/fs/path.go

@@ -0,0 +1,276 @@
+package fs
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	errTooManyLinks = errors.New("too many links")
+)
+
+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 both of the
+		// files, check content of file to determine difference
+		if t1.Nanosecond() == 0 && t2.Nanosecond() == 0 {
+			var eq bool
+			if (f1.f.Mode() & os.ModeSymlink) == os.ModeSymlink {
+				eq, err = compareSymlinkTarget(f1.fullPath, f2.fullPath)
+			} else 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
+}
+
+func compareSymlinkTarget(p1, p2 string) (bool, error) {
+	t1, err := os.Readlink(p1)
+	if err != nil {
+		return false, err
+	}
+	t2, err := os.Readlink(p2)
+	if err != nil {
+		return false, err
+	}
+	return t1 == t2, 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
+	}
+}
+
+// RootPath joins a path with a root, evaluating and bounding any
+// symlink to the root directory.
+func RootPath(root, path string) (string, error) {
+	if path == "" {
+		return root, nil
+	}
+	var linksWalked int // to protect against cycles
+	for {
+		i := linksWalked
+		newpath, err := walkLinks(root, path, &linksWalked)
+		if err != nil {
+			return "", err
+		}
+		path = newpath
+		if i == linksWalked {
+			newpath = filepath.Join("/", newpath)
+			if path == newpath {
+				return filepath.Join(root, newpath), nil
+			}
+			path = newpath
+		}
+	}
+}
+
+func walkLink(root, path string, linksWalked *int) (newpath string, islink bool, err error) {
+	if *linksWalked > 255 {
+		return "", false, errTooManyLinks
+	}
+
+	path = filepath.Join("/", path)
+	if path == "/" {
+		return path, false, nil
+	}
+	realPath := filepath.Join(root, path)
+
+	fi, err := os.Lstat(realPath)
+	if err != nil {
+		// If path does not yet exist, treat as non-symlink
+		if os.IsNotExist(err) {
+			return path, false, nil
+		}
+		return "", false, err
+	}
+	if fi.Mode()&os.ModeSymlink == 0 {
+		return path, false, nil
+	}
+	newpath, err = os.Readlink(realPath)
+	if err != nil {
+		return "", false, err
+	}
+	if filepath.IsAbs(newpath) && strings.HasPrefix(newpath, root) {
+		newpath = newpath[:len(root)]
+		if !strings.HasPrefix(newpath, "/") {
+			newpath = "/" + newpath
+		}
+	}
+	*linksWalked++
+	return newpath, true, nil
+}
+
+func walkLinks(root, path string, linksWalked *int) (string, error) {
+	switch dir, file := filepath.Split(path); {
+	case dir == "":
+		newpath, _, err := walkLink(root, file, linksWalked)
+		return newpath, err
+	case file == "":
+		if os.IsPathSeparator(dir[len(dir)-1]) {
+			if dir == "/" {
+				return dir, nil
+			}
+			return walkLinks(root, dir[:len(dir)-1], linksWalked)
+		}
+		newpath, _, err := walkLink(root, dir, linksWalked)
+		return newpath, err
+	default:
+		newdir, err := walkLinks(root, dir, linksWalked)
+		if err != nil {
+			return "", err
+		}
+		newpath, islink, err := walkLink(root, filepath.Join(newdir, file), linksWalked)
+		if err != nil {
+			return "", err
+		}
+		if !islink {
+			return newpath, nil
+		}
+		if filepath.IsAbs(newpath) {
+			return newpath, nil
+		}
+		return filepath.Join(newdir, newpath), nil
+	}
+}

vendor/github.com/containerd/continuity/fs/stat_bsd.go

@@ -0,0 +1,28 @@
+// +build darwin freebsd
+
+package fs
+
+import (
+	"syscall"
+	"time"
+)
+
+// StatAtime returns the access time from a stat struct
+func StatAtime(st *syscall.Stat_t) syscall.Timespec {
+	return st.Atimespec
+}
+
+// StatCtime returns the created time from a stat struct
+func StatCtime(st *syscall.Stat_t) syscall.Timespec {
+	return st.Ctimespec
+}
+
+// StatMtime returns the modified time from a stat struct
+func StatMtime(st *syscall.Stat_t) syscall.Timespec {
+	return st.Mtimespec
+}
+
+// StatATimeAsTime returns the access time as a time.Time
+func StatATimeAsTime(st *syscall.Stat_t) time.Time {
+	return time.Unix(int64(st.Atimespec.Sec), int64(st.Atimespec.Nsec)) // nolint: unconvert
+}

vendor/github.com/containerd/continuity/fs/stat_linux.go

@@ -0,0 +1,27 @@
+package fs
+
+import (
+	"syscall"
+	"time"
+)
+
+// StatAtime returns the Atim
+func StatAtime(st *syscall.Stat_t) syscall.Timespec {
+	return st.Atim
+}
+
+// StatCtime returns the Ctim
+func StatCtime(st *syscall.Stat_t) syscall.Timespec {
+	return st.Ctim
+}
+
+// StatMtime returns the Mtim
+func StatMtime(st *syscall.Stat_t) syscall.Timespec {
+	return st.Mtim
+}
+
+// StatATimeAsTime returns st.Atim as a time.Time
+func StatATimeAsTime(st *syscall.Stat_t) time.Time {
+	// The int64 conversions ensure the line compiles for 32-bit systems as well.
+	return time.Unix(int64(st.Atim.Sec), int64(st.Atim.Nsec)) // nolint: unconvert
+}

vendor/github.com/containerd/continuity/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))
+}

vendor/github.com/containerd/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/containerd/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/containerd/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/containerd/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/containerd/continuity/sysx/chmod_freebsd.go

@@ -0,0 +1,17 @@
+package sysx
+
+const (
+	// AtSymlinkNoFollow defined from AT_SYMLINK_NOFOLLOW in <sys/fcntl.h>
+	AtSymlinkNofollow = 0x200
+)
+
+const (
+
+	// SYS_FCHMODAT defined from golang.org/sys/unix
+	SYS_FCHMODAT = 490
+)
+
+// These functions will be generated by generate.sh
+//    $ GOOS=freebsd GOARCH=amd64 ./generate.sh chmod
+
+//sys  Fchmodat(dirfd int, path string, mode uint32, flags int) (err error)

vendor/github.com/containerd/continuity/sysx/chmod_freebsd_amd64.go

@@ -0,0 +1,25 @@
+// mksyscall.pl chmod_freebsd.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/containerd/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/containerd/continuity/sysx/chmod_solaris.go

@@ -0,0 +1,11 @@
+package sysx
+
+import "golang.org/x/sys/unix"
+
+const (
+	AtSymlinkNofollow = unix.AT_SYMLINK_NOFOLLOW
+)
+
+func Fchmodat(dirfd int, path string, mode uint32, flags int) error {
+	return unix.Fchmodat(dirfd, path, mode, flags)
+}

vendor/github.com/containerd/continuity/sysx/nodata_linux.go

@@ -0,0 +1,7 @@
+package sysx
+
+import (
+	"syscall"
+)
+
+const ENODATA = syscall.ENODATA

vendor/github.com/containerd/continuity/sysx/nodata_solaris.go

@@ -0,0 +1,8 @@
+package sysx
+
+import (
+	"syscall"
+)
+
+// This should actually be a set that contains ENOENT and EPERM
+const ENODATA = syscall.ENOENT

vendor/github.com/containerd/continuity/sysx/nodata_unix.go

@@ -0,0 +1,9 @@
+// +build darwin freebsd
+
+package sysx
+
+import (
+	"syscall"
+)
+
+const ENODATA = syscall.ENOATTR

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

@@ -0,0 +1,67 @@
+package sysx
+
+import (
+	"bytes"
+	"fmt"
+	"syscall"
+)
+
+const defaultXattrBufferSize = 5
+
+var ErrNotSupported = fmt.Errorf("not supported")
+
+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/containerd/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/containerd/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/containerd/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/containerd/continuity/sysx/xattr_freebsd.go

@@ -0,0 +1,12 @@
+package sysx
+
+import (
+	"errors"
+)
+
+// Initial stub version for FreeBSD. FreeBSD has a different
+// syscall API from Darwin and Linux for extended attributes;
+// it is also not widely used. It is not exposed at all by the
+// Go syscall package, so we need to implement directly eventually.
+
+var unsupported = errors.New("extended attributes unsupported on FreeBSD")

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

@@ -0,0 +1,44 @@
+package sysx
+
+import "golang.org/x/sys/unix"
+
+// Listxattr calls syscall listxattr and reads all content
+// and returns a string array
+func Listxattr(path string) ([]string, error) {
+	return listxattrAll(path, unix.Listxattr)
+}
+
+// Removexattr calls syscall removexattr
+func Removexattr(path string, attr string) (err error) {
+	return unix.Removexattr(path, attr)
+}
+
+// Setxattr calls syscall setxattr
+func Setxattr(path string, attr string, data []byte, flags int) (err error) {
+	return unix.Setxattr(path, attr, data, flags)
+}
+
+// Getxattr calls syscall getxattr
+func Getxattr(path, attr string) ([]byte, error) {
+	return getxattrAll(path, attr, unix.Getxattr)
+}
+
+// LListxattr lists xattrs, not following symlinks
+func LListxattr(path string) ([]string, error) {
+	return listxattrAll(path, unix.Llistxattr)
+}
+
+// LRemovexattr removes an xattr, not following symlinks
+func LRemovexattr(path string, attr string) (err error) {
+	return unix.Lremovexattr(path, attr)
+}
+
+// LSetxattr sets an xattr, not following symlinks
+func LSetxattr(path string, attr string, data []byte, flags int) (err error) {
+	return unix.Lsetxattr(path, attr, data, flags)
+}
+
+// LGetxattr gets an xattr, not following symlinks
+func LGetxattr(path, attr string) ([]byte, error) {
+	return getxattrAll(path, attr, unix.Lgetxattr)
+}

vendor/github.com/containerd/continuity/sysx/xattr_openbsd.go

@@ -0,0 +1,7 @@
+package sysx
+
+import (
+	"errors"
+)
+
+var unsupported = errors.New("extended attributes unsupported on OpenBSD")

vendor/github.com/containerd/continuity/sysx/xattr_solaris.go

@@ -0,0 +1,12 @@
+package sysx
+
+import (
+	"errors"
+)
+
+// Initial stub version for Solaris. Solaris has a different
+// syscall API from Darwin and Linux for extended attributes;
+// it is also not widely used. It is not exposed at all by the
+// Go syscall package, so we need to implement directly eventually.
+
+var unsupported = errors.New("extended attributes unsupported on Solaris")

vendor/github.com/containerd/continuity/sysx/xattr_unsupported.go

@@ -0,0 +1,44 @@
+// +build freebsd openbsd solaris
+
+package sysx
+
+// Listxattr calls syscall listxattr and reads all content
+// and returns a string array
+func Listxattr(path string) ([]string, error) {
+	return []string{}, nil
+}
+
+// Removexattr calls syscall removexattr
+func Removexattr(path string, attr string) (err error) {
+	return unsupported
+}
+
+// Setxattr calls syscall setxattr
+func Setxattr(path string, attr string, data []byte, flags int) (err error) {
+	return unsupported
+}
+
+// Getxattr calls syscall getxattr
+func Getxattr(path, attr string) ([]byte, error) {
+	return []byte{}, unsupported
+}
+
+// LListxattr lists xattrs, not following symlinks
+func LListxattr(path string) ([]string, error) {
+	return []string{}, nil
+}
+
+// LRemovexattr removes an xattr, not following symlinks
+func LRemovexattr(path string, attr string) (err error) {
+	return unsupported
+}
+
+// LSetxattr sets an xattr, not following symlinks
+func LSetxattr(path string, attr string, data []byte, flags int) (err error) {
+	return unsupported
+}
+
+// LGetxattr gets an xattr, not following symlinks
+func LGetxattr(path, attr string) ([]byte, error) {
+	return []byte{}, nil
+}