On Wed, Aug 24, 2016 at 10:02:39AM -0700, Junio C Hamano wrote:
> Jeff King <peff@xxxxxxxx> writes:
>
> > On Wed, Aug 24, 2016 at 09:09:06AM -0700, Junio C Hamano wrote:
> >
> >> > + if (!path)
> >> > + path = obj_context.path;
> >> > + else if (obj_context.mode == S_IFINVALID)
> >> > + obj_context.mode = 0100644;
> >> > +
> >> > buf = NULL;
> >> > switch (opt) {
> >> > case 't':
> >>
> >> The above two hunks make all the difference in the ease of reading
> >> the remainder of the function. Very good.
> >
> > Yeah, I agree. Though it took me a moment to figure out why we were
> > setting obj_context.mode but not obj_context.path; the reason is that
> > "mode" is convenient to use as local storage, but "path" is not, because
> > it is not a pointer but an array.
>
> Wait a minute. Why is it a cascaded if/elseif, not two independent
> if statements that gives a default value? In other words, wouldn't
> these two independent and orthogonal decisions?
>
> * When forced to use some path, we ignore obj_context.path
>
> * Whether we are forced to use a path or not, if we do not know the
> mode from the lookup context, we want to use the regular blob
> mode.
>
> So that part of the patch is wrong after all, I would have to say.
>
> if (!path)
> path = obj_context.path;
> if (obj_context.mode == S_IFINVALID)
> obj_context.mode = 0100644;
>
> or something like that, perhaps.
Oh, hrm, you are right. I assumed we wanted to force the mode when
--path was in effect, but that is not what the original does. If you
say:
--path=foo HEAD:bar
then we will take the mode for "bar", whatever it is (maybe a tree or
symlink). But if you say:
--path=foo $(git rev-parse HEAD:bar)
then we will use 100644, regardless of what "bar" is in HEAD.
I have not thought about it enough to know if that is a good thing or a
bad thing. But I'll bet Dscho has, so I will wait for him to comment. :)
> > if (!force_path) {
> > /* use file info from sha1 lookup */
> > path = obj_context.path;
> > mode = obj_context.mode;
> > } else {
> > /* use path requested by user, and assume it is a regular file */
> > path = force_path;
> > mode = 0100644;
> > }
>
> Hmph, if you read it that way, then if/elseif makes some sense, but
> we need to assume that the obj_context.mode can be garbage and have
> a fallback for it.
>
> Just like
>
> git cat-file --filters --path=git.c HEAD:t
>
> would error out because HEAD:t is not even a blob, I would expect
>
> git cat-file --filters --path=git.c :RelNotes
>
> to error out, because the object itself _is_ known to be a
> blob that is not a regular file.
>
> And that kind of type checking will not be possible with "if the
> user gave us a path, assume it is a regular file".
Right, I agree that is the outcome, but I just wasn't sure that the
second case _should_ error out. IOW, does "--filters --path" mean "treat
this as a regular file at path X", or is the "regular file" part not
implied?
I don't suppose anybody cares that much either way, but it feels weird
to behave differently depending on how we looked up the blob (whereas
for the HEAD:t case, a tree is always a tree).
-Peff
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