Re: Bug in "git rev-parse --verify"

From: Michael Haggerty <mhagger@alum.mit.edu>
Date: Mar 28, 2013, 15:34 UTC
Message-ID: <515462FB.9040605@alum.mit.edu>
In-Reply-To: <CAPc5daUqzz=9TBmj2Q0MHqEc6gMHxXoGr9+JV3hq76zDKJAyCw@mail.gmail.com>

On 03/28/2013 02:48 PM, Junio C Hamano wrote:

> I think it has always been about "is this well formed and we can turn it
> into a raw 20-byte object name?" and never about"does it exist?"

That's surprising.  The man page says

    --verify
        The parameter given must be usable as a single, valid object name.
        Otherwise barf and abort.

"Valid", to me, implies that the parameter should be the name of an actual object, and this also seems a more useful concept to me and more consistent with the command's behavior when passed other arguments.

Is there a simple way to verify an object name more strictly and convert it to an SHA1? I can only think of solutions that require two commands, like

    git cat-file -e $ARG && git rev-parse --verify $ARG

I suppose in most contexts where one wants to know whether an object name is valid, one should also verify that the object has the type that you expect:

    test X$(git cat-file -t $ARG) = Xcommit &&
        git rev-parse --verify $ARG

or (allowing tag dereferencing)

    git cat-file -e $ARG^{commit} &&
        git rev-parse --verify $ARG^{commit}

Michael

-- 
Michael Haggerty
mhagger@alum.mit.edu
http://softwareswirl.blogspot.com/