Re: git cat-file --batch surprising carriage return behavior

From: Jeff King <peff@peff.net>
Date: Oct 11, 2019, 06:21 UTC
Message-ID: <20191011062136.GA25741@sigill.intra.peff.net>
In-Reply-To: <20191009152851.GC19679@kitenet.net>

On Wed, Oct 09, 2019 at 11:28:51AM -0400, Joey Hess wrote:

Show 7 quoted lines

> > I suspect it's not entirely sufficient for clean input, though. You're
> > not feeding filenames but rather full "object names". I wouldn't be
> > surprised if we mis-parse "$rev:$path" when $path has "@{}" or similar
> > in it.
> 
> Nothing I've tried along the lines of "HEAD:{yesterday}" has misparsed
> the part after the colon as anything but a filename.

It's possible we've fixed them all. We definitely don't parse strictly left-to-right. The first thing we try to do is strip bits like ^{commit} off the end, before we even find the colon. But after doing so, we should generally be left with a resolvable name, and I think that uses the "basic" parser which will not allow colons. I.e., this:

  mkdir subdir
  echo whatever >subdir/file
  git add subdir
  git commit -m 'add directory'
  git show HEAD:subdir^{tree}

really does look for the file "subdir^{tree}" in HEAD, and not "HEAD:subdir" as a tree.

We have had bugs in the past; I'm thinking specifically of 8cd4249c4c (interpret_branch_name: always respect "namelen" parameter, 2014-01-15). But I couldn't find any problematic inputs after poking around for a few minutes.

> The one I can think of where there's a parse ambiguity is that while
> :foo gets file foo, :1:foo does not get file "1:foo". Instead it's
> treated as a stage number. Using either HEAD:1:foo or :./1:foo
> will avoid that ambiguity.

Yeah, that makes sense.

-Peff