[Dovecot] Bug when a duplicated file is found

[Angel L. Mateo]

Hello,

	Last days we had to restore some mailboxes from backup. Our mailboxes 
are in maildir format and during restore, some duplicated files 
appeared. The situation is:

* A user has messages in his new directory when the backup is made
* In some moment after the backup is done, the user accesses to his 
mailbox, so the message is move to the cur directory.
* We restore his mailbox directly to his maildir path, so the message is 
now at new directory too.

	When this happens, dovecot detect it and it renames one of the files. 
This is the reported log:

Feb 13 23:08:05 myotis31 dovecot: imap(<user>): Warning: Fixed a 
duplicate: 
/home/alumnos/59/122559/Maildir/cur/1360169810.M670208P13643.myotis31,S=6282,W=6409:2, 
-> 1360793285.M721935P29136.myotis31

	The problem with this is that we are using zlib plugin so messages are 
compressed. When the rename is done, the rename is to a name without the 
S=XXXX field (neither the W=XXX, although this field is less sensible), 
so the result is that user's can't access to any message after this one.

	I think than in this situation, rename one of the files is a good 
solution (although it provokes duplicate mails, but this an 
expected/acceptable situation after the restore), but the rename should 
maintain the S= and W= fields (and even other maildir flags).

-- 
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337