Re: git rev-list %an, %ae, %at bug in v1.7.10.1 and beyond

[Jeff King <peff@peff.net>]

On Tue, May 22, 2012 at 03:13:09PM +1000, Bryan Turner wrote:

> I went and spoke to the tester who made the original commit, and it
> sounds like what he did was open .git/config with a text editor and
> update the user.name directly. He then saved the file. His operating
> system's code page was UTF-16LE, so I believe the file was saved in
> that format. He then did the commit.

That doesn't make sense. Git will not read a config file in utf16
(again, because of the NULs). Nor can you store NULs with "git config
user.name ...". So I'm not sure how utf16 might have made it there.

> That sort of behavior is pretty far outside the scope of anything git
> can realistically be expected to handle (and I told the tester that as
> well). That said, I'm interested that it "suddenly" broke, and also
> that cat-file still appears to not think there's any problem.

Yeah, I'm worried that it's indicative of a bug that might affect other
cases.

> I piped the output through xxd, for cat-file and rev-list. The
> cat-file output is the same in both versions of git, and looks like
> this:
> auri:qa-resources.git bturner$ git cat-file -p
> 5c1ccdec5f84aa149a4978f729fdda70769f942f | xxd
> 0000000: 7472 6565 2064 6431 3733 6362 3730 6261  tree dd173cb70ba
> 0000010: 6161 6330 3762 6466 3430 3566 3465 3364  aac07bdf405f4e3d
> 0000020: 6231 3130 6537 6661 6664 3138 300a 7061  b110e7fafd180.pa
> 0000030: 7265 6e74 2030 3263 3738 6263 3339 6163  rent 02c78bc39ac
> 0000040: 3631 3932 3632 3362 6630 3830 6533 6532  6192623bf080e3e2
> 0000050: 6163 3839 3261 3466 3537 3634 630a 6175  ac892a4f5764c.au
> 0000060: 7468 6f72 2061 203c 6661 726d 6173 4061  thor a <farmas@a
> 0000070: 746c 6173 7369 616e 2e63 6f6d 3e20 3133  tlassian.com> 13
> 0000080: 3237 3837 3632 3232 202b 3131 3030 0a63  27876222 +1100.c
> 0000090: 6f6d 6d69 7474 6572 2061 203c 6661 726d  ommitter a <farm
> 00000a0: 6173 4061 746c 6173 7369 616e 2e63 6f6d  as@atlassian.com
> 00000b0: 3e20 3133 3237 3837 3632 3232 202b 3131  > 1327876222 +11
> 00000c0: 3030 0a0a 636f 6d6d 6974 2077 6974 6820  00..commit with
> 00000d0: 756e 6963 6f64 6520 6e61 6d65 0a         unicode name.

But I don't see any unicode at all here. The author and committer names
are just ascii 'a'. However, that seems to be the real problem. If I
create a commit with a single-letter name, I see some weirdness:

  $ git init
  $ echo content >foo && git add foo
  $ GIT_AUTHOR_NAME=a git commit -m msg
   Author:  <>
   1 file changed, 1 insertion(+)
   create mode 100644 foo

Uh oh, that's odd. And worse:

  $ git log -1 --format='|%an <%ae>|'
  | <>|

But in v1.7.10:

  $ git log -1 --format='|%an <%ae>|'
  |a <peff@peff.net>|

So there is definitely a bug. The unicode thing is a red herring, and if
there was any unicode at some point, git stripped it out when making the
commit. The real regression seems to be in single-character names.

I'll see if I can find the bug.

-Peff