Respect $HOME/tilde expansion in rc.conf file paths

[sevmonster]

With user mode, it would be helpful to parse the $HOME parameter and/or do tilde (~) expansion in rc.conf, at the very least. This would be useful for setting e.g. rc_log_dir="$HOME/.var/log" in a shared config file that could then be linked in all users' OpenRC directories. Without this feature, the config file must be customized for each individual user.

It would be helpful to parse all parameters, not just $HOME, but I don't see that as being superbly useful. Maybe parsing the XDG parameters would be good, since $XDG_RUNTIME_DIR is actually used by OpenRC.

I was actually under the impression this did work at first, since when rc.conf gets sourced by shells, it does expand parameters as expected. However, all the C-side functions I read through that parse values from rc.conf do not do any shell expansion. Due to this, you can have a single config file that has properties with two different values depending on how the file was initially loaded.

[navi-desu]

this sounds like a good idea. we could use wordexp on the c side to perform shell-like expansions easily.

[navi-desu]

there's one kinda major issue though, env_filter needs the config, and we shouldn't expand envs before filtering them... hmm...