How does The login sceen knows my custom wallpaper if i have my home folder permission to 700?

Question

On Ubuntu, if i set my home folder permissions to 700, the login screen can't access my wallpaper so it always display the default one.

On Elementary OS, even if my home folder permission is set to 700, the wallpaper is shown on the login screen.

I noticed that if i change the permissions on the wallpaper file to just be accessed by the user this doesn't happen anymore.

Does it make a copy of the wallpaper to anywhere else than ~/.local/share/backgrounds/ ?

Sorry if is not a serious issue, but I'm just curious how it works.

Answer 1

The answear is that it makes a copy with the same permissions in the root folder /var/lib/lightdm-data/.

This way no matter what your home folder permissions are you will always have the choice to show or not your wallpaper on the login screen by giving the wallpaper file read permissions to others.