From: Junio C Hamano Date: Thu, 08 Aug 2013 21:38:31 GMT Subject: Re: [PATCH] replace: forbid replacing an object with one of a different type Message-ID: <7vsiyj982w.fsf@alter.siamese.dyndns.org> In-Reply-To: "Philip Oakley" writes: > From: "Christian Couder" > Sent: Wednesday, August 07, 2013 5:42 AM >> Users replacing an object with one of a different type were not >> prevented to do so, even if it was obvious, and stated in the doc, >> that bad things would result from doing that. >> >> To avoid mistakes, it is better to just forbid that though. >> >> The doc will be updated in a later patch. >> >> Signed-off-by: Christian Couder >> --- >> If this patch is considered useful, I will update the doc and >> maybe add tests. > > Acked-by: Philip Oakley > Improved documentation would always be useful. Will wait for a reroll with tests and doc updates, then. >> @@ -100,6 +101,14 @@ static int replace_object(const char *object_ref, >> const char *replace_ref, >> if (check_refname_format(ref, 0)) >> die("'%s' is not a valid ref name.", ref); >> >> + obj_type = sha1_object_info(object, NULL); >> + repl_type = sha1_object_info(repl, NULL); > > Do (very) large blobs have any issues here? As I understand it, such > blobs, as with other smaller objects, need to be expanded to determine > the type. sha1_object_info() is coded to peek into only the early part of a loose object or the object header part of a packed object. Loose ones we do mmap(), but we only inflate a tiny bit (the first 32 bytes). >> + if (obj_type != repl_type) >> + die("Object ref '%s' is of type '%s'\n" >> + "while replace ref '%s' is of type '%s'.", >> + object_ref, typename(obj_type), >> + replace_ref, typename(repl_type)); > > Perhaps start with "Objects must be of the same type.\n" Yes.