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

From: Jeff King <peff@peff.net>
Date: May 22, 2012, 04:32 UTC
Message-ID: <20120522043221.GA6859@sigill.intra.peff.net>
In-Reply-To: <CAGyf7-G3nNTTP1bKdd9HLKEn-8+LoxCeY2R08x9gKZwS0L_N6g@mail.gmail.com>

On Mon, May 21, 2012 at 06:01:50PM +1000, Bryan Turner wrote:

Show 10 quoted lines

> Note that the author name, e-mail and timestamp values are all missing
> (the three |'s in a row at the end).
> [...]
> Built from 0dbe6592ccbd1a394a69a52074e3729d546fe952, the parent of
> 4b340cf, and in previous versions of git (1.7.10 and earlier), I got
> output like this:
> [...]
> Note that the author name, e-mail and timestamp are all present. The
> "a" appears as ASCII here, but it's actually a UTF-16LE character (the
> terminal on the Mac is being "helpful").

I'm not too surprised this is broken (in fact, I'm surprised it ever really worked). UTF-16, especially representing pure ascii characters, will have embedded NULs. Most of the code assumes that things like names and emails are NUL-terminated and ascii-compatible (so ascii, or some ascii-superset encoding like utf8, iso8859-1, etc). You can store a commit message (and name) in utf-16 if you tell git that you are doing so, but we should be re-encoding it before handling it.

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> ================================ Output =====================================
> aphrael:qa-resources.git bturner$ git cat-file -p
> 5c1ccdec5f84aa149a4978f729fdda70769f942f
> tree dd173cb70baaac07bdf405f4e3db110e7fafd180
> parent 02c78bc39ac6192623bf080e3e2ac892a4f5764c
> author a <farmas@atlassian.com> 1327876222 +1100
> committer a <farmas@atlassian.com> 1327876222 +1100
> 
> commit with unicode name
> ================================ End ========================================

There's no encoding header, so having a utf-16 character there is wrong. How did you make such a commit in the first place, though? I believe that git-commit treats the name as a string and would terminate on a NUL (or am I wrong in thinking that this "a" is really U+0061, and is actually some other unicode character that _looks_ like "a", but doesn't contain a NUL?).

Did you create it by piping straight to git-hash-object? What does piping the above through "xxd" or "cat -A" show?

-Peff