Corrupted index cache file - migration with zlib

[Robert L Mathews]

On 1/14/16 8:51 PM, Leon Kyneur wrote:
> figured out my issue
> 
> I changed:
> protocol imap {
>   mail_plugins = quota imap_quota imap_zlib
> }
> 
> to this:
> protocol imap {
>   mail_plugins = $mail_plugins imap_quota imap_zlib
> }
>

Right. This is because it needs the "zlib" plugin enabled, and in your
original configuration, the zlib plugin was enabled systemwide:

> mail_plugins = quota zlib

... but these lines completely replaced the "mail_plugins" setting for
imap, and didn't include zlib:

> protocol imap {
>   mail_plugins = quota imap_quota imap_zlib
> }

Your fixed configuration *adds* additional plugins to the systemwide
mail_plugins setting rather than replacing them, so it correctly uses
zlib for IMAP. It would also work if you used:

protocol imap {
   mail_plugins = quota zlib imap_quota imap_zlib
 }


> No longer getting the error after migration with zlib enabled.. could
there
> be any kind of better warning or error handling around this? (if this is
> the actual issue)

Well, the documentation at <http://wiki.dovecot.org/Plugins/Zlib> does
suggest doing it with "mail_plugins = $mail_plugins zlib", and it gives
those errors in the log if you forget it.

There's an argument to be made for "Dovecot should *always* try to
uncompress 'obviously' compressed files", that apparently opens up
security issues, exposing Dovecot to bugs in the system's compression
libraries even if the admin intentionally doesn't use compression.

-- 
Robert L Mathews, Tiger Technologies, http://www.tigertech.net/