feat: better $HOME detection

[dimaqq]

Specifically, trust $HOME if it's set

[PietroPasotti]

@dimaqq this apparently breaks jhack if snapped. also, TIL, Path("~").expanduser() internally uses the HOME envvar so the code I had before is functionally equivalent, only we swapped the priority of USER and HOME. I'm switching that back hoping it will solve the issue.

[PietroPasotti]

in the case of snapped jhack I'm afraid HOME will be set to the snap home dir, which we don't care about, so instead looking up USER first seems to give the desired behaviour. Was the priority swapping intentional, and if so, what were you trying to solve?

[dimaqq]

Oh, that's a problem...

I'm running a colima VM, and it's default is to create a user same as my host user, so dima, but the home dir is /home/dima.linux which means concatenating /home/ and username doesn't do the right thing.

I wonder if expanding ~ yields real home dir or snap home dir...

Or would it help to select a few candidate directories and test if they actually exist?

[dimaqq]

Looking at https://snapcraft.io/docs/home-interface if jhack snap declares the home plug, should it not just work?

[PietroPasotti]

we already have and

so I was expecting it would work out of the box

[dimaqq]

dot files are not part of the home interface

home interface is not the same as personal files interface.

[dimaqq]

See e.g. https://github.com/juju/juju/blob/3.6/snap/snapcraft.yaml#L58-L59

[dimaqq]

Anyway, if jhack doesn't need arbitrary files from user's home, then the personal files plug/interface should be enough. It's then only a matter of guessing the path to the config files consistently whether snapped or not... right?

[PietroPasotti]

correct. I'm not convinced requesting home is the solution here

[PietroPasotti]

also, turns out we already have the home plug too

[dimaqq]

Should we check $SNAP_REAL_HOME first?

Here's the environment from snapped juju:

root@colima-ahh:/home/dima.linux# cat /proc/3015028/environ | tr \\0 \\n | grep -i home
HOME=/home/dima.linux/snap/juju/27226
OLDPWD=/home/dima.linux
SNAP_USER_DATA=/home/dima.linux/snap/juju/27226
SNAP_USER_COMMON=/home/dima.linux/snap/juju/common
PWD=/home/dima.linux
SNAP_REAL_HOME=/home/dima.linux

[PietroPasotti]

huh, if that's guaranteed to be set...