[Dovecot] Segfault when opening a public folder, dovecot 1.1 beta4

[Timo Sirainen]

On Sat, 2007-10-27 at 17:42 -0400, Adam McDougall wrote:
> If you don't need the other groups in Dovecot you can get rid of them and 
>     just have the process use the user's primary group and mail_extra_groups. I 
>     think this should work:
>     
>     userdb passwd {
>       args = system_user=
>     }
>   
>   Actually, yes I like this alot and put this change into production.  I was 
>   planning on using some secondary groups to prevent filesystem access, but
>   I can accomplish the same protection easier with this and mail_extra_groups.
>   Thanks!  I didn't test yet that the secondary groups aren't loaded but I will
>   sometime.
> 
> According to my logs, it seems it does not prevent the secondary groups.
> I'd look at the code to see how it works, but I have to switch tasks and
> may not work more with dovecot until tomorrow.  I suppose if I cannot get
> this to work, it sounds like I may be able to depend on the patch below.

Looks like it overrides the system_user with empty value and Dovecot
ends up calling initgroups(""). I'm not sure what that does, if
anything. This fixes it: http://hg.dovecot.org/dovecot/rev/7f2501b3e993
    
>   >> With some recent permission changes I've
>   >> done (affects dovecot 1.0 as well), I get a good amount of these fchown 
>   >> errors
>   >> and I was thinking of muting them so they do not fill my log, since they 
>   >> are harmless
>   >> in my setup.
>     
>     If these errors happen for index files Dovecot currently fallbacks to using 
>     in-memory indexes.
>   
>   Oh. Ugh. That might explain why the indexes don't always seem to load.
>   For some reason I thought dovecot might print a message when it falls back
>   to in-memory indexes; would that be possible?

Possible yes, but I'm not sure if it's a good idea. Users with
filesystem quotas probably wouldn't want to see them. It's anyway done
silently only when write fails because of ENOSPC/EDQUOT, in other cases
some error is always logged.

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