Re: Other format of cyrus.header file?

Yep, that's the new "dlist header file" format.  And you're right, we should document it!

It appeared with this commit:

commit 29bce1f64de17e108adef0f814a3165888ca06a5
Author: Ken Murchison <[email protected]>
Date:   Thu Oct 25 14:24:13 2018 -0400

    mailbox.c: use dlist to store cyrus.header data, including mboxname and mbtype

And it was changed because the old format was very hard to safely extend.  DLIST is a Cyrus internal format that I first wrote for the new replication engine in 2.4, back in 2010.  It's not as efficient as JSON and I'm kind of tempted to move to JSON - but it is very similar to IMAP list syntax, so it was easy to build tooling for.

Bron.

On Thu, Sep 18, 2025, at 17:56, [email protected] wrote:
> Hi,
> 
> I noticed a difference in the format of the cyrus.header file. Older files correspond to the specification according to the documentation:
> 
> <Mailbox Header Magic String>
> <Quota Root>\t<Mailbox Unique ID String>\n
> <Space-separated list of user flags>\n
> <Mailbox ACL>\n
> 
> e.g.
> user.such^such^cz       cu3zc27vvohouoi31e513ii2
> 
> such.such.cz    lrswipkxtecdan  cyrus   lrswipkxtecda
> 
> However, in current files, information about user flags and ACL is on a single line, e.g.:
> 
> %(T el N user.such^such^cz.Linkedin I 5rhsan0cost2tdsgd2g2vt3s Q user.such^such^cz A %(such.such.cz lrswipkxtecdan cyrus lrswipkxtecda) U (NonJunk $NotJunk NotJunk $Forwarded JunkRecorded $J
> unk Junk))
> 
> Since when and why is it now created this way? And why isn't it in the documentation?
> 
> regards
> 
> Milan
> *Cyrus <https://cyrus.topicbox.com/latest>* / Info / see discussions <https://cyrus.topicbox.com/groups/info> + participants <https://cyrus.topicbox.com/groups/info/members> + delivery options <https://cyrus.topicbox.com/groups/info/subscription> Permalink <https://cyrus.topicbox.com/groups/info/T232c4031ec6fdae2-Mb2df99d0e706d1f0c6428126>

--
  Bron Gondwana, CEO, Fastmail Pty Ltd / Fastmail US LLC
  [email protected]


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