Create directories for subgroups.

group/description.go

@@ -380,7 +380,14 @@ func rewriteDescriptionFile(filename string, desc *Description) error {
 		return ErrDescriptionsNotWritable
 	}
 
-	f, err := os.CreateTemp(path.Dir(filename), "*.temp")
+	dir := filepath.Dir(filename)
+
+	err = os.MkdirAll(dir, 0700)
+	if err != nil {
+		return err
+	}
+
+	f, err := os.CreateTemp(dir, "*.temp")
 	if err != nil {
 		return err
 	}

group/description_test.go

@@ -306,3 +306,15 @@ func TestWritableGroups(t *testing.T) {
 		)
 	}
 }
+
+func TestSubGroup(t *testing.T) {
+	err := setupTest(t.TempDir(), t.TempDir(), true)
+	if err != nil {
+		t.Fatalf("setupTest: %v", err)
+	}
+
+	err = UpdateDescription("dir/test", "", &Description{})
+	if err != nil {
+		t.Fatalf("UpdateDescription: got %v", err)
+	}
+}