Re: fsck: BAD_FILEMODE diagnostic broken / never triggers

From: Jeff King <peff@peff.net>
Date: Aug 9, 2022, 22:48 UTC
Message-ID: <YvLkU3X9lBsG8wXp@coredump.intra.peff.net>
In-Reply-To: <B3488A12-BCE3-48C8-915C-E2AC4E71ECD2@masklinn.net>

On Sat, Aug 06, 2022 at 03:43:56PM +0200, Xavier Morel wrote:

Show 9 quoted lines

> However looking at fsck_tree, it does have a fair amount of code to
> validate entry modes and a dedicated message id for this (BAD_FILEMODE
> / badFilemode), it even has a code path for legacy entries with
> S_IWGRP set (extensively documented under `git fsck --strict`).
> 
> I guess, over time mode canonicalisation has slowly creeped earlier
> the tree-parsing code, and (seemingly for several years) it has been
> occurring before "git fsck" gets tree entry information, so git fsck
> simply can not see invalid entry modes?

Yes, I think you're right. I didn't bisect, but I suspect this goes back to 7146e66f08 (tree-walk: finally switch over tree descriptors to contain a pre-parsed entry, 2014-02-06).

We probably need to provide version of decode_tree_entry() which gives the non-canonical mode, and to call it from fsck.

-Peff