Re: [PATCH 0/3] --end-of-options marker

From: Jeff King <peff@peff.net>
Date: Aug 8, 2019, 10:28 UTC
Message-ID: <20190808102857.GD12257@sigill.intra.peff.net>
In-Reply-To: <20190807041749.GI118825@genre.crustytoothpaste.net>

On Wed, Aug 07, 2019 at 04:17:49AM +0000, brian m. carlson wrote:

Show 9 quoted lines

> > I think if we at least choose the left-most "--" as the official
> > end-of-options then they can't inject an option (they can only inject a
> > rev as a path). I guess that's the same as with --end-of-options. But it
> > somehow feels less clear to me than a separate marker.
> 
> I suppose if there's more than two, then interpret the first one as the
> end-of-options marker, the second one in the traditional way, and any
> subsequent ones as pathspecs matching the file "--". Writing such a
> command line would be silly, but we'd fail secure.

Yeah, I think that could work. I'd be a little concerned that the implementation would end up complicated and confusing, just because there are other parts of the code that treat "--" specially. That's not a necessarily a reason to avoid it if there's a compelling reason, but I think I favor a unique marker anyway (or at least am otherwise ambivalent).

> That's a good point. I don't have a strong view either way, but I
> thought I'd ask about alternatives.

Discussion of alternatives is very welcome.

I think the most compelling alternative is the one I pointed out in one of the commit messages:

  git rev-list --revision=<whatever>

which lets normal left-to-right parsing work without any complex reasoning. It is harder to use with "$@", though.

Related, my proposal doesn't do anything for rev-parse. I think that:

  git rev-parse --end-of-options -xyz

should probably return:

  --end-of-options
  <oid of -xyz>

but I mostly consider that kind of use of rev-parse (pretending to be an options parser for rev-list) to be vestigial. The main use of rev-parse (in my experience) is "rev-parse --verify" to resolve a single name.

There are still some gaps there. For instance:

  git rev-parse --verify --foo

will treat "--foo" as an option (and then complain that there was no rev argument). I don't think you can do anything too mischievous from this, but it might be nice to tighten it up. I'm tempted to say that "--verify" should complain if there isn't exactly one argument, but technically things like this do work:

  git rev-parse --verify --sq "$rev"

  git rev-parse --verify --symbolic-full-name "$rev"

I don't know if anybody cares or not. We could perhaps work around it by having --verify treat the final argument as a non-option, even if it starts with "-". That would allow those cases, but:

  git rev-parse --verify --symbolic-full-name

would treat the latter as an argument (and currently that's always an error anyway). Looking at rev-parse, there are other weird bits to --verify, too. E.g., this:

  git rev-parse --verify a...b c

shows a...b, ignoring that --verify was given, and then eventually "c".

-Peff