How do I reclaim a disown'd process?

Similar to many previous questions, I found myself running a job that I wish I had run in screen. I was forced to disown the process because I needed to disconnect. Now that I have reconnected, I see that the process is still running. How can I "reclaim" the process, so that I can see its output and give it input?

This question is distinct from just moving a running process to screen, in that it involves reopening lost stdin/out/err handles.

This is a duplicate question — see Moving an already-running process to Screen , which points to retty, which is a self-described horrible hack implementing what I'd always guessed might be possible but never really tried: it finds fd 0, 1, and 2 (standard in, out, and error, respectively) for the process and attaches to them, like a horrible aberrant parasite which should not be.

By disowning the process, you are effectively saying that you want it to ignore SIGHUPs issued by the terminal. Once you close your session (say, bash), this process will then become owned by init. So when you say you want to re-own a process after you've given up ownership, you're saying you want to take ownership away from another process--which isn't implemented, and for good reason. This just isn't possible to do gracefully in Linux.