Feat: import file from existing outer folder

pkg/filesystem/manage.go

@@ -285,6 +285,38 @@ func (fs *FileSystem) List(ctx context.Context, dirPath string, pathProcessor fu
 	return fs.listObjects(ctx, parentPath, childFiles, childFolders, pathProcessor), nil
 }
 
+// ListPhysical 列出存储策略中的外部目录
+// TODO:测试
+func (fs *FileSystem) ListPhysical(ctx context.Context, dirPath string) ([]Object, error) {
+	if err := fs.DispatchHandler(); fs.Policy == nil || err != nil {
+		return nil, ErrUnknownPolicyType
+	}
+
+	// 存储策略不支持列取时，返回空结果
+	if !fs.Policy.CanStructureBeListed() {
+		return nil, nil
+	}
+
+	// 列取路径
+	objects, err := fs.Handler.List(ctx, dirPath, false)
+	if err != nil {
+		return nil, err
+	}
+
+	var (
+		folders []model.Folder
+	)
+	for _, object := range objects {
+		if object.IsDir {
+			folders = append(folders, model.Folder{
+				Name: object.Name,
+			})
+		}
+	}
+
+	return fs.listObjects(ctx, dirPath, nil, folders, nil), nil
+}
+
 func (fs *FileSystem) listObjects(ctx context.Context, parent string, files []model.File, folders []model.Folder, pathProcessor func(string) string) []Object {
 	// 分享文件的ID
 	shareKey := ""