On Wed, Jun 08, 2022 at 04:08:03PM -0400, Derrick Stolee wrote: > I'd love to see the full binary, but for the sake of sharing on the > list, could you give the following output? > > xxd .git/objects/info/commit-graph | head > > or any other command that shows the first few hex bytes along with > their ASCII equivalents. Here is one that used Git 2.34.0: > [...] Interesting. My earlier email was a bit misleading. I do in fact have a GDA2 chunk. And looking at the timestamp on the commit-graph file, it's from May 24th. I hadn't been keeping the repo up to date regularly, but I did occasionally pull and rebuild. So I think it was a much more recent version of Git that built the problematic file, though it's possible it was carrying forward bad data. So 6dbf4b8172ef may be a bit of a red herring, if the file has a GDA2 section that was simply ignored before that commit. Looking at my reflog, my best guess for the version of Git that produced the file is e46751e96fa. > However, the lack of the large offset chunk could be due to the bug fixed by > 75979d9460 (commit-graph: fix ordering bug in generation numbers, > 2022-03-01). Perhaps that was the thing that was missing from your version? So I _think_ I would have had that, though there's a good chance that an older version of the commit-graph file was written using a version of Git without it. > But otherwise, I'm stumped. I'd be very interested to see a repro from a > fresh repository. That is: what situation do we need to be in to write such > an offset without including the large offset chunk? Not exactly a fresh reproduction, but you can grab my broken file from: https://peff.net/tmp/broken-commit-graph Dropping it into a fresh clone of git.git shows the problem. I tried a few obvious from-scratch reproductions like building a file with 75979d9460^ (so with the generation number bug), and then jumping forward to e46751e96fa (so bug fixed, but now we write GDA2), but couldn't get it to trigger. It may not be worth spending too much time on, if this is a weird one-off caused by a mix of buggy unreleased versions of Git. If real users aren't seeing it, and we know the nuclear option is "rm commit-graph", then that may be enough. -Peff
