title: Change directory in a server without leaving the working directory
body: <p>I have a server. Client can send a path and server should <code>cd</code> to that path. But here is the thing. Imagine I have a <code>test2</code> directory in <code>test1</code> directory and the path to <code>test1</code> directory is <code>C:\test1</code>. The client can access <code>test2</code> by <code>cd test2</code> and <code>\test1\test2</code> and if he wants to go back he can use <code>\test1</code> (I searched and found <code>os.chdir</code> but it needs the full path and I don't have it) and he shouldn't be free to send <code>E:\something</code> or anything like that. Just the directories that are in <code>test1</code>. what do you suggest? what can I use to achieve this?</p>