#vulnerable code 
                             public boolean deleteFromFileBlocks(Node f) {
		// 先判断一下文件块所在的存储区
		File rootPath = new File(ConfigureReader.instance().getFileBlockPath());
		if (!f.getFilePath().startsWith("file_")) {// 存放于主文件系统中
			short index = Short.parseShort(f.getFilePath().substring(0, f.getFilePath().indexOf('_')));
			rootPath = ConfigureReader.instance().getExtendStores().parallelStream()
					.filter((e) -> e.getIndex() == index).findAny().get().getPath();
		}
		// 获取对应的文件块对象
		File file = getFileFromBlocks(f);
		if (file != null) {
			if (file.delete()) {
				File parentPath = file.getParentFile();
				while (parentPath != null && parentPath.isDirectory() && (!parentPath.equals(rootPath))
						&& parentPath.list().length == 0) {
					File thisPath = parentPath;
					parentPath = thisPath.getParentFile();
					thisPath.delete();
				}
				return true;
			}
		}
		return false;
	} 
                            #location 6 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             public boolean deleteFromFileBlocks(Node f) {
		// 获取对应的文件块对象
		File file = getFileFromBlocks(f);
		if (file != null) {
			return file.delete();// 执行删除操作
		}
		return false;
	}