restore: remove unexpected xattrs from files

internal/restic/node_xattr.go

@@ -40,6 +40,11 @@ func setxattr(path, name string, data []byte) error {
 	return handleXattrErr(xattr.LSet(path, name, data))
 }
 
+// removexattr removes the attribute name from path.
+func removexattr(path, name string) error {
+	return handleXattrErr(xattr.LRemove(path, name))
+}
+
 func handleXattrErr(err error) error {
 	switch e := err.(type) {
 	case nil:
@@ -70,12 +75,29 @@ func (node *Node) fillGenericAttributes(_ string, _ os.FileInfo, _ *statT) (allo
 }
 
 func (node Node) restoreExtendedAttributes(path string) error {
+	expectedAttrs := map[string]struct{}{}
 	for _, attr := range node.ExtendedAttributes {
 		err := setxattr(path, attr.Name, attr.Value)
 		if err != nil {
 			return err
 		}
+		expectedAttrs[attr.Name] = struct{}{}
 	}
+
+	// remove unexpected xattrs
+	xattrs, err := listxattr(path)
+	if err != nil {
+		return err
+	}
+	for _, name := range xattrs {
+		if _, ok := expectedAttrs[name]; ok {
+			continue
+		}
+		if err := removexattr(path, name); err != nil {
+			return err
+		}
+	}
+
 	return nil
 }
 

internal/restic/node_xattr_all_test.go

@@ -0,0 +1,44 @@
+//go:build darwin || freebsd || linux || solaris || windows
+// +build darwin freebsd linux solaris windows
+
+package restic
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	rtest "github.com/restic/restic/internal/test"
+)
+
+func setAndVerifyXattr(t *testing.T, file string, attrs []ExtendedAttribute) {
+	node := Node{
+		ExtendedAttributes: attrs,
+	}
+	rtest.OK(t, node.restoreExtendedAttributes(file))
+
+	nodeActual := Node{}
+	rtest.OK(t, nodeActual.fillExtendedAttributes(file, false))
+
+	rtest.Assert(t, nodeActual.sameExtendedAttributes(node), "xattr mismatch got %v expected %v", nodeActual.ExtendedAttributes, node.ExtendedAttributes)
+}
+
+func TestOverwriteXattr(t *testing.T) {
+	dir := t.TempDir()
+	file := filepath.Join(dir, "file")
+	rtest.OK(t, os.WriteFile(file, []byte("hello world"), 0o600))
+
+	setAndVerifyXattr(t, file, []ExtendedAttribute{
+		{
+			Name:  "user.foo",
+			Value: []byte("bar"),
+		},
+	})
+
+	setAndVerifyXattr(t, file, []ExtendedAttribute{
+		{
+			Name:  "user.other",
+			Value: []byte("some"),
+		},
+	})
+}