Re: [PATCH 1/1] upload-pack: fix race condition in error messages

From: SZEDER Gábor <szeder.dev@gmail.com>
Date: Aug 29, 2019, 21:58 UTC
Message-ID: <20190829215818.GG8571@szeder.dev>
In-Reply-To: <20190829143805.GB1746@sigill.intra.peff.net>

On Thu, Aug 29, 2019 at 10:38:05AM -0400, Jeff King wrote:

Show 5 quoted lines

> So any fixes there have to happen on the client side. I am still
> confused about why the client is writing in this case, per the argument
> in 014ade7484 (upload-pack: send ERR packet for non-tip objects,
> 2019-04-13). It would be nice to use GIT_TRACE_PACKET to see what it's
> trying to write, but I still haven't been able to reproduce the issue.

It's the "done" line:

  + cat trace-packet
  packet:  upload-pack> 5e26403b4485d7a44fd8b65dc3f71e21c0dd6fad HEAD\0multi_ack thin-pack side-band side-band-64k ofs-delta shallow deepen-since deepen-not deepen-relative no-progress include-tag multi_ack_detailed allow-tip-sha1-in-want allow-reachable-sha1-in-want symref=HEAD:refs/heads/master agent=git/2.23.0.40.g4d780d4382.dirty
  packet:  upload-pack> 5e26403b4485d7a44fd8b65dc3f71e21c0dd6fad refs/heads/master
  packet:  upload-pack> 0000
  packet:        fetch< 5e26403b4485d7a44fd8b65dc3f71e21c0dd6fad HEAD\0multi_ack thin-pack side-band side-band-64k ofs-delta shallow deepen-since deepen-not deepen-relative no-progress include-tag multi_ack_detailed allow-tip-sha1-in-want allow-reachable-sha1-in-want symref=HEAD:refs/heads/master agent=git/2.23.0.40.g4d780d4382.dirty
  packet:        fetch< 5e26403b4485d7a44fd8b65dc3f71e21c0dd6fad refs/heads/master
  packet:        fetch< 0000
  packet:        fetch> want 64ea4c133d59fa98e86a771eda009872d6ab2886 multi_ack_detailed side-band-64k thin-pack no-progress ofs-delta deepen-since deepen-not agent=git/2.23.0.40.g4d780d4382.dirty
  packet:        fetch> 0000
  packet:  upload-pack< want 64ea4c133d59fa98e86a771eda009872d6ab2886 multi_ack_detailed side-band-64k thin-pack no-progress ofs-delta deepen-since deepen-not agent=git/2.23.0.40.g4d780d4382.dirty
  packet:  upload-pack< 0000
  packet:  upload-pack> ERR upload-pack: not our ref 64ea4c133d59fa98e86a771eda009872d6ab2886
  packet:  upload-pack> 0000
  packet:        fetch> done

In the avarage successful run that "fetch> done" pkt-line is immediately after the "fetch> 0000".

The above is on my Linux box; here is a failure on macOS, essentially the same:

  https://travis-ci.org/szeder/git/jobs/578555606#L3453