OfflineIMAP/offlineimap

changing nametrans on a local folder invalidates all uids.

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#411 opened on Nov 28, 2016

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 (17 comments) (0 reactions) (0 assignees)Python (1,765 stars) (373 forks)batch import
enhancementgood first issueneed contributor!

Description

Local Maildir folders use the visiblename for computing their md5 hash. See here. In case there is a local nametrans, this is the folder name translated to remote, but with local separator.

This md5 hash is embedded in the maildir files. Additionally, when copying messages to a remote, it is checked whether the message md5 coincides with the actual folder md5. If not, the local uid is made negative, which means the message will get reuploaded, and assigned a new uid on the remote. See this.

Since this has to do with uid validity, which is a remote thing, It probably makes sense to use the md5 hash of the remote folder name.

However, it has unexpected consequences. Changing the local nametrans will invalidate all uids and reupload all messages. This might happen when a user with a partial nametrans only on the remote, adds a local one to have back&forth consistency. The fact that this invalidates all uids is quite unexpected.

I'm not sure what are the options here. Since apparently there has already been a md5 hash migration, we could probably do another one and transition hashes to local folder name.

Contributor guide

Tech stack
python
Domain
backenddata
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Python programmingIMAP and Maildir conceptsofflineimap codebase
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
The issue identifies that changing local nametrans invalidates UIDs because the md5 hash is computed from the visible name of the local folder. To resolve, examine lines 77 and 121 in offlineimap/folder/Maildir.py where the hash is computed and checked. Consider transitioning the hash to use the local folder name as suggested, similar to the previous migration at line 512. Review existing comments for proposed approaches and ensure any change is backward compatible.