Re: Unexpected cat-file --batch-check output

From: Jeff King <peff@peff.net>
Date: Oct 25, 2021, 19:18 UTC
Message-ID: <YXcC8jQbFsaqYN2M@coredump.intra.peff.net>
In-Reply-To: <CAGyf7-HFGgkXsA-MXBOdiogDid+=F8jmqw0zxwQoUzha-jc1Hw@mail.gmail.com>

On Mon, Oct 25, 2021 at 12:02:38PM -0700, Bryan Turner wrote:

Show 13 quoted lines

> I'm working with some users trying to reconcile an odd mismatch
> observed in some Git output.
> 
> Running an ls-tree for a branch and path, limited to a single pattern
> within, shows this:
> /usr/bin/git ls-tree -z refs/heads/develop:path/to/parent – file
> 100644 blob 4c8d566ed80a1554a059b97f7cd533a55bbd2ea8    file
> 
> If we then run cat-file --batch-check, though, we see this:
> echo 'refs/heads/develop
> refs/heads/develop:path/to/parent/file' | /usr/bin/git cat-file --batch-check
> 28a05ce2e3079afcb32e4f1777b42971d7933a91 commit 259
> cc10f4b278086325aab2f95df97c807c7c6cd75e commit 330

That's definitely odd. Some things I'd try:

  - do other versions of cat-file behave differently (i.e., is it a
    regression)?

  - what does "git rev-parse refs/heads/develop:path/to/parent/file"
    say? If it comes up with 4c8d566ed80, then the problem is cat-file
    specific. If not, then it's a problem in the name resolution
    routines.

  - likewise, what does "git cat-file -t cc10f4b27808" say? I'd expect
    it to really be a commit (a bug in batch-check's formatting routines
    could show the wrong object, but I'd expect the oid to at least
    match what ls-tree showed).

  - Is there anything odd about the tree? E.g., duplicate entries, out
    of order entries, etc? Examining "ls-tree" output might help, but
    "git fsck" should also note any irregularities.

After that, I'd probably start running "cat-file --batch-check" through a debugger. I know you said you don't have access to the repository, but perhaps whoever does might be willing to run it through "fast-export --anonymize" and see if the bug persists?

-Peff