Bug#854792: fails when there are two users with the same UID

[Emilio Pozuelo Monfort]

On 10/02/17 13:38, Juan Cespedes wrote:
> Package: accountsservice
> Version: 0.6.43-1
> Severity: serious
> 
> Summary: accounts-daemon.service fails to work properly when there are
> two users in the system with the same UID.  The service is still
> running, but it shows an error message and makes unrelated software
> break: gdm3 waits indefinitely and does not start Xorg at boot time.
> Removing one of the offending users (or changing its UID) and
> restarting accounts-daemon.service makes gdm3 work again.
> 
> Details:
> 
> After upgrading the system to stretch, gdm3 would not start Xorg
> anymore, without giving any error or warning.  After enabling debug
> and restarting, its last message was:
> 
> Feb 10 13:30:17 petete gdm-launch-environment]: AccountsService: ActUserManager: waiting for user manager to load before finding user 'Debian-gdm'
> 
> This made me think there was some problem with accounts-daemon:
> 
> ----8<----8<---
> # systemctl status accounts-daemon | cat
> ● accounts-daemon.service - Accounts Service
>    Loaded: loaded (/lib/systemd/system/accounts-daemon.service; enabled; vendor preset: enabled)
>    Active: active (running) since Fri 2017-02-10 13:19:37 CET; 14min ago
>  Main PID: 29171 (accounts-daemon)
>     Tasks: 3 (limit: 4915)
>    Memory: 1.4M
>       CPU: 81ms
>    CGroup: /system.slice/accounts-daemon.service
>            └─29171 /usr/lib/accountsservice/accounts-daemon
> 
> Feb 10 13:19:36 petete systemd[1]: Stopped Accounts Service.
> Feb 10 13:19:36 petete systemd[1]: Starting Accounts Service...
> Feb 10 13:19:37 petete accounts-daemon[29171]: error exporting user object: An object is already exported for the interface org.freedesktop.Accounts.User at /org/freedesktop/Accounts/User1000
> Feb 10 13:19:37 petete accounts-daemon[29171]: started daemon version 0.6.43
> Feb 10 13:19:37 petete systemd[1]: Started Accounts Service.
> ----8<----8<---
> 
> As you can see, the service is "loaded" and "active", but it shows an
> error about "an object is already exported".  As I said, after
> removing the users with duplicate UIDs, accounts-daemon starts without
> errors, and gdm3 runs fine and starts Xorg properly.

I'm not sure that's a system configuration that is supported. If you shoot
yourself in the foot, you should expect some problems...

Cheers,
Emilio