Merge pull request #3279 from mheon/update_cstorage

Update c/storage to 9b10041d7b2ef767ce9c42b5862b6c51eeb82214

17 files changed, 256 insertions, 58 deletions

diff --git a/vendor/github.com/containers/storage/containers.go b/vendor/github.com/containers/storage/containers.go
index bbac78b60..e69552361 100644
--- a/vendor/github.com/containers/storage/containers.go
+++ b/vendor/github.com/containers/storage/containers.go
@@ -572,6 +572,10 @@ func (r *containerStore) Lock() {
 	r.lockfile.Lock()
 }
 
+func (r *containerStore) RecursiveLock() {
+	r.lockfile.RecursiveLock()
+}
+
 func (r *containerStore) RLock() {
 	r.lockfile.RLock()
 }
diff --git a/vendor/github.com/containers/storage/drivers/aufs/aufs.go b/vendor/github.com/containers/storage/drivers/aufs/aufs.go
index e821bc0c5..353d1707a 100644
--- a/vendor/github.com/containers/storage/drivers/aufs/aufs.go
+++ b/vendor/github.com/containers/storage/drivers/aufs/aufs.go
@@ -255,6 +255,9 @@ func (a *Driver) AdditionalImageStores() []string {
 
 // CreateFromTemplate creates a layer with the same contents and parent as another layer.
 func (a *Driver) CreateFromTemplate(id, template string, templateIDMappings *idtools.IDMappings, parent string, parentIDMappings *idtools.IDMappings, opts *graphdriver.CreateOpts, readWrite bool) error {
+	if opts == nil {
+		opts = &graphdriver.CreateOpts{}
+	}
 	return graphdriver.NaiveCreateFromTemplate(a, id, template, templateIDMappings, parent, parentIDMappings, opts, readWrite)
 }
 
diff --git a/vendor/github.com/containers/storage/drivers/chown.go b/vendor/github.com/containers/storage/drivers/chown.go
index 4d4011ee0..f2f1ec386 100644
--- a/vendor/github.com/containers/storage/drivers/chown.go
+++ b/vendor/github.com/containers/storage/drivers/chown.go
@@ -55,6 +55,9 @@ func chownByMapsMain() {
 		if err != nil {
 			return fmt.Errorf("error walking to %q: %v", path, err)
 		}
+		if path == "." {
+			return nil
+		}
 		return platformLChown(path, info, toHost, toContainer)
 	}
 	if err := filepath.Walk(".", chown); err != nil {
diff --git a/vendor/github.com/containers/storage/images.go b/vendor/github.com/containers/storage/images.go
index 38b5a3ef3..6f487504a 100644
--- a/vendor/github.com/containers/storage/images.go
+++ b/vendor/github.com/containers/storage/images.go
@@ -82,6 +82,9 @@ type Image struct {
 	// is set before using it.
 	Created time.Time `json:"created,omitempty"`
 
+	// ReadOnly is true if this image resides in a read-only layer store.
+	ReadOnly bool `json:"-"`
+
 	Flags map[string]interface{} `json:"flags,omitempty"`
 }
 
@@ -159,6 +162,7 @@ func copyImage(i *Image) *Image {
 		BigDataSizes:    copyStringInt64Map(i.BigDataSizes),
 		BigDataDigests:  copyStringDigestMap(i.BigDataDigests),
 		Created:         i.Created,
+		ReadOnly:        i.ReadOnly,
 		Flags:           copyStringInterfaceMap(i.Flags),
 	}
 }
@@ -269,6 +273,7 @@ func (r *imageStore) Load() error {
 				list := digests[digest]
 				digests[digest] = append(list, image)
 			}
+			image.ReadOnly = !r.IsReadWrite()
 		}
 	}
 	if shouldSave && (!r.IsReadWrite() || !r.Locked()) {
@@ -739,6 +744,10 @@ func (r *imageStore) Lock() {
 	r.lockfile.Lock()
 }
 
+func (r *imageStore) RecursiveLock() {
+	r.lockfile.RecursiveLock()
+}
+
 func (r *imageStore) RLock() {
 	r.lockfile.RLock()
 }
diff --git a/vendor/github.com/containers/storage/layers.go b/vendor/github.com/containers/storage/layers.go
index a35dd476b..fb79238cd 100644
--- a/vendor/github.com/containers/storage/layers.go
+++ b/vendor/github.com/containers/storage/layers.go
@@ -103,6 +103,9 @@ type Layer struct {
 	// for use inside of a user namespace where UID mapping is being used.
 	UIDMap []idtools.IDMap `json:"uidmap,omitempty"`
 	GIDMap []idtools.IDMap `json:"gidmap,omitempty"`
+
+	// ReadOnly is true if this layer resides in a read-only layer store.
+	ReadOnly bool `json:"-"`
 }
 
 type layerMountPoint struct {
@@ -259,6 +262,7 @@ func copyLayer(l *Layer) *Layer {
 		UncompressedDigest: l.UncompressedDigest,
 		UncompressedSize:   l.UncompressedSize,
 		CompressionType:    l.CompressionType,
+		ReadOnly:           l.ReadOnly,
 		Flags:              copyStringInterfaceMap(l.Flags),
 		UIDMap:             copyIDMap(l.UIDMap),
 		GIDMap:             copyIDMap(l.GIDMap),
@@ -318,6 +322,7 @@ func (r *layerStore) Load() error {
 			if layer.MountLabel != "" {
 				label.ReserveLabel(layer.MountLabel)
 			}
+			layer.ReadOnly = !r.IsReadWrite()
 		}
 		err = nil
 	}
@@ -1304,6 +1309,10 @@ func (r *layerStore) Lock() {
 	r.lockfile.Lock()
 }
 
+func (r *layerStore) RecursiveLock() {
+	r.lockfile.RecursiveLock()
+}
+
 func (r *layerStore) RLock() {
 	r.lockfile.RLock()
 }
diff --git a/vendor/github.com/containers/storage/layers_ffjson.go b/vendor/github.com/containers/storage/layers_ffjson.go
index 09b5d0f33..125b5d8c9 100644
--- a/vendor/github.com/containers/storage/layers_ffjson.go
+++ b/vendor/github.com/containers/storage/layers_ffjson.go
@@ -1,5 +1,5 @@
 // Code generated by ffjson <https://github.com/pquerna/ffjson>. DO NOT EDIT.
-// source: ./layers.go
+// source: layers.go
 
 package storage
 
diff --git a/vendor/github.com/containers/storage/lockfile.go b/vendor/github.com/containers/storage/lockfile.go
index ed8753337..c4f1b5549 100644
--- a/vendor/github.com/containers/storage/lockfile.go
+++ b/vendor/github.com/containers/storage/lockfile.go
@@ -15,6 +15,10 @@ type Locker interface {
 	// Acquire a writer lock.
 	Lock()
 
+	// Acquire a writer lock recursively, allowing for recursive acquisitions
+	// within the same process space.
+	RecursiveLock()
+
 	// Unlock the lock.
 	Unlock()
 
diff --git a/vendor/github.com/containers/storage/lockfile_linux.go b/vendor/github.com/containers/storage/lockfile_linux.go
deleted file mode 100644
index 903387c66..000000000
--- a/vendor/github.com/containers/storage/lockfile_linux.go
+++ /dev/null
@@ -1,20 +0,0 @@
-// +build linux solaris
-
-package storage
-
-import (
-	"time"
-
-	"golang.org/x/sys/unix"
-)
-
-// TouchedSince indicates if the lock file has been touched since the specified time
-func (l *lockfile) TouchedSince(when time.Time) bool {
-	st := unix.Stat_t{}
-	err := unix.Fstat(int(l.fd), &st)
-	if err != nil {
-		return true
-	}
-	touched := time.Unix(st.Mtim.Unix())
-	return when.Before(touched)
-}
diff --git a/vendor/github.com/containers/storage/lockfile_otherunix.go b/vendor/github.com/containers/storage/lockfile_otherunix.go
deleted file mode 100644
index 041d54c05..000000000
--- a/vendor/github.com/containers/storage/lockfile_otherunix.go
+++ /dev/null
@@ -1,19 +0,0 @@
-// +build darwin freebsd
-
-package storage
-
-import (
-	"time"
-
-	"golang.org/x/sys/unix"
-)
-
-func (l *lockfile) TouchedSince(when time.Time) bool {
-	st := unix.Stat_t{}
-	err := unix.Fstat(int(l.fd), &st)
-	if err != nil {
-		return true
-	}
-	touched := time.Unix(st.Mtimespec.Unix())
-	return when.Before(touched)
-}
diff --git a/vendor/github.com/containers/storage/lockfile_unix.go b/vendor/github.com/containers/storage/lockfile_unix.go
index 8e0f22cb5..00215e928 100644
--- a/vendor/github.com/containers/storage/lockfile_unix.go
+++ b/vendor/github.com/containers/storage/lockfile_unix.go
@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/containers/storage/pkg/stringid"
+	"github.com/containers/storage/pkg/system"
 	"github.com/pkg/errors"
 	"golang.org/x/sys/unix"
 )
@@ -25,6 +26,7 @@ type lockfile struct {
 	locktype   int16
 	locked     bool
 	ro         bool
+	recursive  bool
 }
 
 // openLock opens the file at path and returns the corresponding file
@@ -75,7 +77,7 @@ func createLockerForPath(path string, ro bool) (Locker, error) {
 
 // lock locks the lockfile via FCTNL(2) based on the specified type and
 // command.
-func (l *lockfile) lock(l_type int16) {
+func (l *lockfile) lock(l_type int16, recursive bool) {
 	lk := unix.Flock_t{
 		Type:   l_type,
 		Whence: int16(os.SEEK_SET),
@@ -86,7 +88,13 @@ func (l *lockfile) lock(l_type int16) {
 	case unix.F_RDLCK:
 		l.rwMutex.RLock()
 	case unix.F_WRLCK:
-		l.rwMutex.Lock()
+		if recursive {
+			// NOTE: that's okay as recursive is only set in RecursiveLock(), so
+			// there's no need to protect against hypothetical RDLCK cases.
+			l.rwMutex.RLock()
+		} else {
+			l.rwMutex.Lock()
+		}
 	default:
 		panic(fmt.Sprintf("attempted to acquire a file lock of unrecognized type %d", l_type))
 	}
@@ -110,6 +118,7 @@ func (l *lockfile) lock(l_type int16) {
 	}
 	l.locktype = l_type
 	l.locked = true
+	l.recursive = recursive
 	l.counter++
 }
 
@@ -119,13 +128,24 @@ func (l *lockfile) Lock() {
 	if l.ro {
 		l.RLock()
 	} else {
-		l.lock(unix.F_WRLCK)
+		l.lock(unix.F_WRLCK, false)
+	}
+}
+
+// RecursiveLock locks the lockfile as a writer but allows for recursive
+// acquisitions within the same process space.  Note that RLock() will be called
+// if it's a lockTypReader lock.
+func (l *lockfile) RecursiveLock() {
+	if l.ro {
+		l.RLock()
+	} else {
+		l.lock(unix.F_WRLCK, true)
 	}
 }
 
 // LockRead locks the lockfile as a reader.
 func (l *lockfile) RLock() {
-	l.lock(unix.F_RDLCK)
+	l.lock(unix.F_RDLCK, false)
 }
 
 // Unlock unlocks the lockfile.
@@ -161,7 +181,7 @@ func (l *lockfile) Unlock() {
 		// Close the file descriptor on the last unlock.
 		unix.Close(int(l.fd))
 	}
-	if l.locktype == unix.F_RDLCK {
+	if l.locktype == unix.F_RDLCK || l.recursive {
 		l.rwMutex.RUnlock()
 	} else {
 		l.rwMutex.Unlock()
@@ -232,3 +252,14 @@ func (l *lockfile) Modified() (bool, error) {
 func (l *lockfile) IsReadWrite() bool {
 	return !l.ro
 }
+
+// TouchedSince indicates if the lock file has been touched since the specified time
+func (l *lockfile) TouchedSince(when time.Time) bool {
+	st, err := system.Fstat(int(l.fd))
+	if err != nil {
+		return true
+	}
+	mtim := st.Mtim()
+	touched := time.Unix(mtim.Unix())
+	return when.Before(touched)
+}
diff --git a/vendor/github.com/containers/storage/lockfile_windows.go b/vendor/github.com/containers/storage/lockfile_windows.go
index c02069495..caf7c184a 100644
--- a/vendor/github.com/containers/storage/lockfile_windows.go
+++ b/vendor/github.com/containers/storage/lockfile_windows.go
@@ -36,6 +36,12 @@ func (l *lockfile) Lock() {
 	l.locked = true
 }
 
+func (l *lockfile) RecursiveLock() {
+	// We don't support Windows but a recursive writer-lock in one process-space
+	// is really a writer lock, so just panic.
+	panic("not supported")
+}
+
 func (l *lockfile) RLock() {
 	l.mu.Lock()
 	l.locked = true
diff --git a/vendor/github.com/containers/storage/pkg/chrootarchive/archive.go b/vendor/github.com/containers/storage/pkg/chrootarchive/archive.go
index a36ff1cb1..33ba6a128 100644
--- a/vendor/github.com/containers/storage/pkg/chrootarchive/archive.go
+++ b/vendor/github.com/containers/storage/pkg/chrootarchive/archive.go
@@ -1,7 +1,7 @@
 package chrootarchive
 
 import (
-	"archive/tar"
+	stdtar "archive/tar"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -34,18 +34,34 @@ func NewArchiverWithChown(tarIDMappings *idtools.IDMappings, chownOpts *idtools.
 // The archive may be compressed with one of the following algorithms:
 //  identity (uncompressed), gzip, bzip2, xz.
 func Untar(tarArchive io.Reader, dest string, options *archive.TarOptions) error {
-	return untarHandler(tarArchive, dest, options, true)
+	return untarHandler(tarArchive, dest, options, true, dest)
+}
+
+// UntarWithRoot is the same as `Untar`, but allows you to pass in a root directory
+// The root directory is the directory that will be chrooted to.
+// `dest` must be a path within `root`, if it is not an error will be returned.
+//
+// `root` should set to a directory which is not controlled by any potentially
+// malicious process.
+//
+// This should be used to prevent a potential attacker from manipulating `dest`
+// such that it would provide access to files outside of `dest` through things
+// like symlinks. Normally `ResolveSymlinksInScope` would handle this, however
+// sanitizing symlinks in this manner is inherrently racey:
+// ref: CVE-2018-15664
+func UntarWithRoot(tarArchive io.Reader, dest string, options *archive.TarOptions, root string) error {
+	return untarHandler(tarArchive, dest, options, true, root)
 }
 
 // UntarUncompressed reads a stream of bytes from `archive`, parses it as a tar archive,
 // and unpacks it into the directory at `dest`.
 // The archive must be an uncompressed stream.
 func UntarUncompressed(tarArchive io.Reader, dest string, options *archive.TarOptions) error {
-	return untarHandler(tarArchive, dest, options, false)
+	return untarHandler(tarArchive, dest, options, false, dest)
 }
 
 // Handler for teasing out the automatic decompression
-func untarHandler(tarArchive io.Reader, dest string, options *archive.TarOptions, decompress bool) error {
+func untarHandler(tarArchive io.Reader, dest string, options *archive.TarOptions, decompress bool, root string) error {
 	if tarArchive == nil {
 		return fmt.Errorf("Empty archive")
 	}
@@ -77,7 +93,15 @@ func untarHandler(tarArchive io.Reader, dest string, options *archive.TarOptions
 		r = decompressedArchive
 	}
 
-	return invokeUnpack(r, dest, options)
+	return invokeUnpack(r, dest, options, root)
+}
+
+// Tar tars the requested path while chrooted to the specified root.
+func Tar(srcPath string, options *archive.TarOptions, root string) (io.ReadCloser, error) {
+	if options == nil {
+		options = &archive.TarOptions{}
+	}
+	return invokePack(srcPath, options, root)
 }
 
 // CopyFileWithTarAndChown returns a function which copies a single file from outside
@@ -99,7 +123,7 @@ func CopyFileWithTarAndChown(chownOpts *idtools.IDPair, hasher io.Writer, uidmap
 			var hashWorker sync.WaitGroup
 			hashWorker.Add(1)
 			go func() {
-				t := tar.NewReader(contentReader)
+				t := stdtar.NewReader(contentReader)
 				_, err := t.Next()
 				if err != nil {
 					hashError = err
diff --git a/vendor/github.com/containers/storage/pkg/chrootarchive/archive_unix.go b/vendor/github.com/containers/storage/pkg/chrootarchive/archive_unix.go
index e04ed787c..ca9fb10d7 100644
--- a/vendor/github.com/containers/storage/pkg/chrootarchive/archive_unix.go
+++ b/vendor/github.com/containers/storage/pkg/chrootarchive/archive_unix.go
@@ -10,10 +10,13 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"runtime"
+	"strings"
 
 	"github.com/containers/storage/pkg/archive"
 	"github.com/containers/storage/pkg/reexec"
+	"github.com/pkg/errors"
 )
 
 // untar is the entry-point for storage-untar on re-exec. This is not used on
@@ -23,18 +26,28 @@ func untar() {
 	runtime.LockOSThread()
 	flag.Parse()
 
-	var options *archive.TarOptions
+	var options archive.TarOptions
 
 	//read the options from the pipe "ExtraFiles"
 	if err := json.NewDecoder(os.NewFile(3, "options")).Decode(&options); err != nil {
 		fatal(err)
 	}
 
-	if err := chroot(flag.Arg(0)); err != nil {
+	dst := flag.Arg(0)
+	var root string
+	if len(flag.Args()) > 1 {
+		root = flag.Arg(1)
+	}
+
+	if root == "" {
+		root = dst
+	}
+
+	if err := chroot(root); err != nil {
 		fatal(err)
 	}
 
-	if err := archive.Unpack(os.Stdin, "/", options); err != nil {
+	if err := archive.Unpack(os.Stdin, dst, &options); err != nil {
 		fatal(err)
 	}
 	// fully consume stdin in case it is zero padded
@@ -45,7 +58,10 @@ func untar() {
 	os.Exit(0)
 }
 
-func invokeUnpack(decompressedArchive io.Reader, dest string, options *archive.TarOptions) error {
+func invokeUnpack(decompressedArchive io.Reader, dest string, options *archive.TarOptions, root string) error {
+	if root == "" {
+		return errors.New("must specify a root to chroot to")
+	}
 
 	// We can't pass a potentially large exclude list directly via cmd line
 	// because we easily overrun the kernel's max argument/environment size
@@ -57,7 +73,21 @@ func invokeUnpack(decompressedArchive io.Reader, dest string, options *archive.T
 		return fmt.Errorf("Untar pipe failure: %v", err)
 	}
 
-	cmd := reexec.Command("storage-untar", dest)
+	if root != "" {
+		relDest, err := filepath.Rel(root, dest)
+		if err != nil {
+			return err
+		}
+		if relDest == "." {
+			relDest = "/"
+		}
+		if relDest[0] != '/' {
+			relDest = "/" + relDest
+		}
+		dest = relDest
+	}
+
+	cmd := reexec.Command("storage-untar", dest, root)
 	cmd.Stdin = decompressedArchive
 
 	cmd.ExtraFiles = append(cmd.ExtraFiles, r)
@@ -68,6 +98,7 @@ func invokeUnpack(decompressedArchive io.Reader, dest string, options *archive.T
 	if err := cmd.Start(); err != nil {
 		return fmt.Errorf("Untar error on re-exec cmd: %v", err)
 	}
+
 	//write the options to the pipe for the untar exec to read
 	if err := json.NewEncoder(w).Encode(options); err != nil {
 		return fmt.Errorf("Untar json encode to pipe failed: %v", err)
@@ -84,3 +115,92 @@ func invokeUnpack(decompressedArchive io.Reader, dest string, options *archive.T
 	}
 	return nil
 }
+
+func tar() {
+	runtime.LockOSThread()
+	flag.Parse()
+
+	src := flag.Arg(0)
+	var root string
+	if len(flag.Args()) > 1 {
+		root = flag.Arg(1)
+	}
+
+	if root == "" {
+		root = src
+	}
+
+	if err := realChroot(root); err != nil {
+		fatal(err)
+	}
+
+	var options archive.TarOptions
+	if err := json.NewDecoder(os.Stdin).Decode(&options); err != nil {
+		fatal(err)
+	}
+
+	rdr, err := archive.TarWithOptions(src, &options)
+	if err != nil {
+		fatal(err)
+	}
+	defer rdr.Close()
+
+	if _, err := io.Copy(os.Stdout, rdr); err != nil {
+		fatal(err)
+	}
+
+	os.Exit(0)
+}
+
+func invokePack(srcPath string, options *archive.TarOptions, root string) (io.ReadCloser, error) {
+	if root == "" {
+		return nil, errors.New("root path must not be empty")
+	}
+
+	relSrc, err := filepath.Rel(root, srcPath)
+	if err != nil {
+		return nil, err
+	}
+	if relSrc == "." {
+		relSrc = "/"
+	}
+	if relSrc[0] != '/' {
+		relSrc = "/" + relSrc
+	}
+
+	// make sure we didn't trim a trailing slash with the call to `Rel`
+	if strings.HasSuffix(srcPath, "/") && !strings.HasSuffix(relSrc, "/") {
+		relSrc += "/"
+	}
+
+	cmd := reexec.Command("storage-tar", relSrc, root)
+
+	errBuff := bytes.NewBuffer(nil)
+	cmd.Stderr = errBuff
+
+	tarR, tarW := io.Pipe()
+	cmd.Stdout = tarW
+
+	stdin, err := cmd.StdinPipe()
+	if err != nil {
+		return nil, errors.Wrap(err, "error getting options pipe for tar process")
+	}
+
+	if err := cmd.Start(); err != nil {
+		return nil, errors.Wrap(err, "tar error on re-exec cmd")
+	}
+
+	go func() {
+		err := cmd.Wait()
+		err = errors.Wrapf(err, "error processing tar file: %s", errBuff)
+		tarW.CloseWithError(err)
+	}()
+
+	if err := json.NewEncoder(stdin).Encode(options); err != nil {
+		stdin.Close()
+		return nil, errors.Wrap(err, "tar json encode to pipe failed")
+	}
+	stdin.Close()
+
+	return tarR, nil
+}
diff --git a/vendor/github.com/containers/storage/pkg/chrootarchive/archive_windows.go b/vendor/github.com/containers/storage/pkg/chrootarchive/archive_windows.go
index 93fde4220..8a5c680b1 100644
--- a/vendor/github.com/containers/storage/pkg/chrootarchive/archive_windows.go
+++ b/vendor/github.com/containers/storage/pkg/chrootarchive/archive_windows.go
@@ -14,9 +14,16 @@ func chroot(path string) error {
 
 func invokeUnpack(decompressedArchive io.ReadCloser,
 	dest string,
-	options *archive.TarOptions) error {
+	options *archive.TarOptions, root string) error {
 	// Windows is different to Linux here because Windows does not support
 	// chroot. Hence there is no point sandboxing a chrooted process to
 	// do the unpack. We call inline instead within the daemon process.
 	return archive.Unpack(decompressedArchive, longpath.AddPrefix(dest), options)
 }
+
+func invokePack(srcPath string, options *archive.TarOptions, root string) (io.ReadCloser, error) {
+	// Windows is different to Linux here because Windows does not support
+	// chroot. Hence there is no point sandboxing a chrooted process to
+	// do the pack. We call inline instead within the daemon process.
+	return archive.TarWithOptions(srcPath, options)
+}
diff --git a/vendor/github.com/containers/storage/pkg/chrootarchive/chroot_unix.go b/vendor/github.com/containers/storage/pkg/chrootarchive/chroot_unix.go
index f9b5dece8..83278ee50 100644
--- a/vendor/github.com/containers/storage/pkg/chrootarchive/chroot_unix.go
+++ b/vendor/github.com/containers/storage/pkg/chrootarchive/chroot_unix.go
@@ -4,9 +4,13 @@ package chrootarchive
 
 import "golang.org/x/sys/unix"
 
-func chroot(path string) error {
+func realChroot(path string) error {
 	if err := unix.Chroot(path); err != nil {
 		return err
 	}
 	return unix.Chdir("/")
 }
+
+func chroot(path string) error {
+	return realChroot(path)
+}
diff --git a/vendor/github.com/containers/storage/pkg/chrootarchive/init_unix.go b/vendor/github.com/containers/storage/pkg/chrootarchive/init_unix.go
index 21cd87992..ea08135e4 100644
--- a/vendor/github.com/containers/storage/pkg/chrootarchive/init_unix.go
+++ b/vendor/github.com/containers/storage/pkg/chrootarchive/init_unix.go
@@ -14,6 +14,7 @@ import (
 func init() {
 	reexec.Register("storage-applyLayer", applyLayer)
 	reexec.Register("storage-untar", untar)
+	reexec.Register("storage-tar", tar)
 }
 
 func fatal(err error) {
diff --git a/vendor/github.com/containers/storage/pkg/system/stat_unix.go b/vendor/github.com/containers/storage/pkg/system/stat_unix.go
index 91c7d121c..f9a1b4877 100644
--- a/vendor/github.com/containers/storage/pkg/system/stat_unix.go
+++ b/vendor/github.com/containers/storage/pkg/system/stat_unix.go
@@ -58,3 +58,15 @@ func Stat(path string) (*StatT, error) {
 	}
 	return fromStatT(s)
 }
+
+// Fstat takes an open file descriptor and returns
+// a system.StatT type pertaining to that file.
+//
+// Throws an error if the file descriptor is invalid
+func Fstat(fd int) (*StatT, error) {
+	s := &syscall.Stat_t{}
+	if err := syscall.Fstat(fd, s); err != nil {
+		return nil, err
+	}
+	return fromStatT(s)
+}