On Wed, Aug 07, 2019 at 04:17:49AM +0000, brian m. carlson wrote: > On 2019-08-06 at 23:43:20, Jeff King wrote: > > On Tue, Aug 06, 2019 at 10:58:53PM +0000, brian m. carlson wrote: > > > Sorry, I hadn't had a chance to look at this series in depth, but I was > > > wondering: could we not just accept two separate "--" arguments, and if > > > there are two of them, interpret the first with the traditional meaning > > > and the second with the Git-specific meaning? That would be much more > > > intuitive for folks, although I suspect it would take a little more work > > > in the options parser. > > > > That also crossed my mind, but I think it opens up some complicated > > corner cases. For instance, if I'm parsing left-to-right and see "--", > > how do I know which separator it is meant to be? I think the only rule > > that makes sense is that you must have two "--", like: > > > > git rev-list [options] -- [revs] -- [paths] > > I was assuming that we wouldn't have a huge number of command-line > arguments and we'd check ahead, although that could of course cause some > pain when used with xargs, I suppose, especially on Linux with its huge > ARG_MAX. > > > but that means parsing the whole thing before we can interpret any of > > it. What kinds of tricks can an attacker play by putting "--" in the > > revs or paths areas? E.g., what does this mean: > > > > # expanded from "git rev-list -- $revs -- $paths" > > git rev-list -- --foo -- -- --bar -- > > > > I think if we at least choose the left-most "--" as the official > > end-of-options then they can't inject an option (they can only inject a > > rev as a path). I guess that's the same as with --end-of-options. But it > > somehow feels less clear to me than a separate marker. This is definitely the secure option among the two, but I'm not sure that it makes me feel better about this alternative direction. I dislike the ambiguity in having two '--'s, and I don't think that this is something we ought to concern callers with. '--end-of-options' is on the one hand, cumbersome to write, but it is clear. I think that this is an acceptable trade-off, because we don't expect users at the command line to ever type this. So, some extra clarity in favor of a drop in convenience for a supposedly smaller number of use cases seems like a favorable trade-off to me. > I suppose if there's more than two, then interpret the first one as the > end-of-options marker, the second one in the traditional way, and any > subsequent ones as pathspecs matching the file "--". Writing such a > command line would be silly, but we'd fail secure. > > > It also doesn't allow this: > > > > # allow paths and revs, with optional separator, but no more options > > git rev-list --end-of-options "$@" > > > > though I'm not sure whether anybody cares. > > That's a good point. I don't have a strong view either way, but I > thought I'd ask about alternatives. > -- > brian m. carlson: Houston, Texas, US > OpenPGP: https://keybase.io/bk2204 Thanks, Taylor
