'open' 事件
当 <fs.ReadStream> 的文件描述符被打开时触发。
fd
<integer> Integer file descriptor used by the <fs.ReadStream>.
Emitted when the <fs.ReadStream>'s file descriptor has been opened.
当 <fs.ReadStream> 的文件描述符被打开时触发。
fd
<integer> Integer file descriptor used by the <fs.ReadStream>.Emitted when the <fs.ReadStream>'s file descriptor has been opened.