Bypass: Refactor request pad function

Minor renames and log changes Use common 'copy_ifo_string' function to fix inconsistency

This mostly makes postcoh's version of the function as consistent with the new version as possible.

I tried to extract more to a common lib, but couldn't find a good way to. Most of the bulk is error checking, ultimately I think I need to learn to skim over it. There's no neat way to clean that up in C, as far as I'm aware.