Use the home directory and other user info from /etc/passwd

[rkday-pro]

When using libnss-ato, we found that we were having to duplictate data - things like the username and home directory had to be specified in both libnss-ato.conf and in /etc/passwd.

This PR tweaks this to pull that data out of /etc/passwd, just using /etc/libnss-ato.conf for the UID of the all-in-one user.

I haven't made this configurable - are there use-cases where someone would want different data for a user than is in /etc/passwd?

[Strykar]

@rkd-msw I haven't made this configurable - are there use-cases where someone would want different data for a user than is in /etc/passwd?
Username and passwords from RADIUS for users with shell:/bin/false - they don't need or have a home directory.
The use case is to manage these non-shell user accounts and their passwords via RADIUS.
For a network-based database of users, you can use LDAP, or maybe MySQL or Postgres. Most RADIUS installations already use SQL or some db. This is a nice hack instead of a hypothetical libnss-radius.

[donapieppo]

Sorry for the delay, was on holiday. I like your idea but it made me think that maybe /etc/libnss-ato.conf should contain only the UID. It would be cleaner (even if not compatibe with old versions of libnss-ato). Whouldn't it?

@Strykar did you mean that this pull would breake something in your use case?

[rkday-pro]

Yes, I think it would be reasonable for it to just have the UID (that's basically all we're using now), but that does mean back-compatibility problems. Maybe it could try and parse the file twice - once as one-UID-per-line, then in /etc/passwd format if that fails?