Update symlink from docker upstream

Signed-off-by: Vincent Demeester <[email protected]>

libcontainer/rootfs_linux.go

@@ -14,10 +14,10 @@ import (
 	"time"
 
 	"github.com/docker/docker/pkg/mount"
-	"github.com/opencontainers/runc/libcontainer/symlink"
 	"github.com/mrunalp/fileutils"
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
+	"github.com/opencontainers/runc/libcontainer/symlink"
 	"github.com/opencontainers/runc/libcontainer/system"
 	libcontainerUtils "github.com/opencontainers/runc/libcontainer/utils"
 	"github.com/opencontainers/selinux/go-selinux/label"

libcontainer/symlink/fs.go

@@ -14,13 +14,14 @@ import (
 	"strings"
 )
 
-// FollowSymlinkInScope is a wrapper around evalSymlinksInScope that returns an absolute path
+// FollowSymlinkInScope is a wrapper around evalSymlinksInScope that returns an
+// absolute path. This function handles paths in a platform-agnostic manner.
 func FollowSymlinkInScope(path, root string) (string, error) {
-	path, err := filepath.Abs(path)
+	path, err := filepath.Abs(filepath.FromSlash(path))
 	if err != nil {
 		return "", err
 	}
-	root, err = filepath.Abs(root)
+	root, err = filepath.Abs(filepath.FromSlash(root))
 	if err != nil {
 		return "", err
 	}
@@ -37,7 +38,7 @@ func FollowSymlinkInScope(path, root string) (string, error) {
 //
 // Example:
 //   If /foo/bar -> /outside,
-//   FollowSymlinkInScope("/foo/bar", "/foo") == "/foo/outside" instead of "/oustide"
+//   FollowSymlinkInScope("/foo/bar", "/foo") == "/foo/outside" instead of "/outside"
 //
 // IMPORTANT: it is the caller's responsibility to call evalSymlinksInScope *after* relevant symlinks
 // are created and not to create subsequently, additional symlinks that could potentially make a
@@ -92,8 +93,8 @@ func evalSymlinksInScope(path, root string) (string, error) {
 		// root gets prepended and we Clean again (to remove any trailing slash
 		// if the first Clean gave us just "/")
 		cleanP := filepath.Clean(string(filepath.Separator) + b.String() + p)
-		if cleanP == string(filepath.Separator) {
-			// never Lstat "/" itself
+		if isDriveOrRoot(cleanP) {
+			// never Lstat "/" itself, or drive letters on Windows
 			b.Reset()
 			continue
 		}
@@ -110,7 +111,8 @@ func evalSymlinksInScope(path, root string) (string, error) {
 			return "", err
 		}
 		if fi.Mode()&os.ModeSymlink == 0 {
-			b.WriteString(p + string(filepath.Separator))
+			b.WriteString(p)
+			b.WriteRune(filepath.Separator)
 			continue
 		}
 
@@ -119,7 +121,7 @@ func evalSymlinksInScope(path, root string) (string, error) {
 		if err != nil {
 			return "", err
 		}
-		if filepath.IsAbs(dest) {
+		if isAbs(dest) {
 			b.Reset()
 		}
 		path = dest + string(filepath.Separator) + path

libcontainer/symlink/fs_unix.go

@@ -0,0 +1,16 @@
+// +build !windows
+
+package symlink
+
+import (
+	"path/filepath"
+)
+
+func isDriveOrRoot(p string) bool {
+	return p == string(filepath.Separator)
+}
+
+// isAbs is a platform-specific wrapper for filepath.IsAbs.
+func isAbs(path string) bool {
+	return filepath.IsAbs(path)
+}