Use/Create PAM extension for better UI support
GDM has support for extensions. They work by setting an environment variable. Each extension enabled extension gets a type, and then binary messages can be send.
Using this, we can replace the string prompts with proper status reporting. Maybe, we should just define a json type or so, and then send json strings?
Note that right now this is only used by SSSD to create drop-down selections.
See gdm-pam-extensions.h
and pam_sssd
.
The main goal here is to remove the need for gnome-shell to talk directly with fprintd. If the messages we implement do not solve this problem, then the whole thing would be pretty useless.