IDA/Hexrays SDK: how to preserve lvar names?

Question

Last night I was extending functionality of HexRaysCodeXplorer - implemented feature to automatically rename duplicating variables. It needs some fixes to work well, but the problem I cannot cope with is - how to preserve lvar names?

This is how it works:

1. Before:

   

2. After:

   

These names do exist only till end of current Ida session.

I have read about Ida's netnodes, but I don't think it's rational to store lvar names in this container and do renaming at the start of every session. I suspect there is some native way to preserve essential information (like in this case), but I cannot find it.

Because I had to analyse c-tree, I used HexRays classes like: ctree_visitor_t, cfuncptr_t and lvar_t.

Answer 1

There's no need to store them. As I'm guessing your lvar name generation algorithm is not very computationally expensive, you can just regenerate them every time a function is decompiled.

(This is the approach used by my CrowdDetox Hex-Rays plugin.)