fs: properly handle ENOTSUP in copyXAttrs

Filesystems without xattr support do not have any xattrs to copy. The
syscall for this will return ENOTSUP to indicate this, but continuity
will treat it as a regular error. This change will return nil if this
call returns ENOTSUP.

Signed-off-by: David Son <davbson@amazon.com>

Author: sondavidb

fs/copy_linux.go

@@ -17,6 +17,7 @@
 package fs
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"syscall"
@@ -64,6 +65,9 @@ func copyFileInfo(fi os.FileInfo, src, name string) error {
 func copyXAttrs(dst, src string, excludes map[string]struct{}, errorHandler XAttrErrorHandler) error {
 	xattrKeys, err := sysx.LListxattr(src)
 	if err != nil {
+		if errors.Is(err, unix.ENOTSUP) {
+			return nil
+		}
 		e := fmt.Errorf("failed to list xattrs on %s: %w", src, err)
 		if errorHandler != nil {
 			e = errorHandler(dst, src, "", e)

fs/copy_unix.go

@@ -20,12 +20,14 @@
 package fs
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"runtime"
 	"syscall"
 
 	"github.com/containerd/continuity/sysx"
+	"golang.org/x/sys/unix"
 )
 
 func copyFileInfo(fi os.FileInfo, src, name string) error {
@@ -67,6 +69,9 @@ func copyXAttrs(dst, src string, excludes map[string]struct{}, errorHandler XAtt
 			// On darwin, character devices do not permit listing xattrs
 			return nil
 		}
+		if errors.Is(err, unix.ENOTSUP) {
+			return nil
+		}
 		e := fmt.Errorf("failed to list xattrs on %s: %w", src, err)
 		if errorHandler != nil {
 			e = errorHandler(dst, src, "", e)