Hi,
I found a problem in the courier conversion script (courier-dovecot-migrate.pl). In some cases, it does not correctly preserve the order of POP3 UIDLs.
Consider the following case, when courierpop3dsizelist contains:
/2 9000 1327481629 AAA1:2,S 10000 21:1327481629 AAA2:2,S 10000 22:1327481629 AAA3:2,S 10000 23:1327481629 AAA4:2,S 10000 24:1327481629 AAA5:2,S 10000 25:1327481629 BBB11:2,S 10000 11:1327481629 BBB12:2,S 10000 12:1327481629 BBB13:2,S 10000 13:1327481629 BBB14:2,S 10000 14:1327481629 BBB15:2,S 10000 15:1327481629
and courierimapuiddb contains:
1 1327480919 9000 11 BBB11 12 BBB12 13 BBB13 14 BBB14 15 BBB15 16 CCC16 17 CCC17 18 CCC18 19 CCC19 20 CCC20 21 AAA1 22 AAA2 23 AAA3 24 AAA4 25 AAA5
then call courier-dovecot-migrate.pl --to-dovecot --convert and it will create dovecot-uidlist:
3 V1327480919 N9010 21 PUID21-1327481629 W10000 :AAA1:2,S 22 PUID22-1327481629 W10000 :AAA2:2,S 23 PUID23-1327481629 W10000 :AAA3:2,S 24 PUID24-1327481629 W10000 :AAA4:2,S 25 PUID25-1327481629 W10000 :AAA5:2,S 9000 :CCC17 9001 PUID12-1327481629 W10000 :BBB12:2,S 9002 :CCC16 9003 PUID15-1327481629 W10000 :BBB15:2,S 9004 :CCC20 9005 PUID14-1327481629 W10000 :BBB14:2,S 9006 PUID13-1327481629 W10000 :BBB13:2,S 9007 :CCC18 9008 PUID11-1327481629 W10000 :BBB11:2,S 9009 :CCC19
The problem here is that the BBB files are not in the same order as in courierpop3dsizelist, and will therefore have a different order in the UIDL response in POP3. Also, the CCC files are interleaved while they should appear at the end.
The reason is how the script assigns new UIDs: It does not do this in the order of courierpop3dsizelist. In fact the order is random because it depends on how perl traverses hashes.
The attached patch fixes this by sorting the messages: First the POP3 messages get their new UIDs in order of their appearance in courierpop3dsizelist (so that the UIDL order will really be the same as in Courier), after that, the IMAP-only messages will be checked for UID clashes. The patch also changes how the $prev_uid variable is handled because that was also needed to always get the order right.
The algorithm could probably be optimized to reduce the number of UID re-assignments to a minimum, however this would complicate the code and would only be noticed in a few cases.
The patched courier-dovecot-migrate.pl will create dovecot-uidlist like this:
3 V1327480919 N9010 21 PUID21-1327481629 W10000 :AAA1:2,S 22 PUID22-1327481629 W10000 :AAA2:2,S 23 PUID23-1327481629 W10000 :AAA3:2,S 24 PUID24-1327481629 W10000 :AAA4:2,S 25 PUID25-1327481629 W10000 :AAA5:2,S 9000 PUID11-1327481629 W10000 :BBB11:2,S 9001 PUID12-1327481629 W10000 :BBB12:2,S 9002 PUID13-1327481629 W10000 :BBB13:2,S 9003 PUID14-1327481629 W10000 :BBB14:2,S 9004 PUID15-1327481629 W10000 :BBB15:2,S 9005 :CCC16 9006 :CCC17 9007 :CCC18 9008 :CCC19 9009 :CCC20
Cheers, Christoph
-- Christoph Bußenius Rechnerbetriebsgruppe der Fakultäten Informatik und Mathematik Technische Universität München +49 89-289-18519 <> Raum 00.05.055 <> Boltzmannstr. 3 <> Garching