On Mon, Nov 22, 2021 at 06:53:23PM +0100, Ævar Arnfjörð Bjarmason wrote:
> Remove unreachable "unknown type" handling in the code that displays
> the ambiguous object list. See [1] for the current output, and [1] for
> the commit that added the "unknown type" handling.
>
> The reason this code wasn't reachable is because we're not passing in
> OBJECT_INFO_ALLOW_UNKNOWN_TYPE, so we'll die in sort_ambiguous()
> before we get to show_ambiguous_object():
>
> $ git rev-parse 8315
> error: short object ID 8315 is ambiguous
> hint: The candidates are:
> fatal: invalid object type
I'm not so sure about this reasoning. In the code we are getting the
type fresh from oid_object_info():
> @@ -361,6 +361,8 @@ static int show_ambiguous_object(const struct object_id *oid, void *data)
> return 0;
>
> type = oid_object_info(ds->repo, oid, NULL);
> + assert(type == OBJ_TREE || type == OBJ_COMMIT ||
> + type == OBJ_BLOB || type == OBJ_TAG);
so at the very least we have to worry about the answer changing between
the two spots. You talk above about ALLOW_UNKNOWN_TYPE, but can't we
just get a straight "-1" if there's an error opening the object?
I'm also confused about the mention of die in sort_ambiguous(). It looks
like it would just produce a funny sort order in that case.
Here's a case that triggers the difference:
git init repo
cd repo
one=$(echo 851 | git hash-object -w --stdin)
two=$(echo 872 | git hash-object -w --stdin)
oid=$(echo $two | cut -c1-4)
fn=.git/objects/$(echo $two | perl -pe 's{..}{$&/}')
chmod +w $fn
echo broken >$fn
git show $oid
Without your patch, it produces:
error: short object ID ee3d is ambiguous
hint: The candidates are:
error: inflate: data stream error (incorrect header check)
error: unable to unpack ee3d8abaa95a7395b373892b2593de2f426814e2 header
error: inflate: data stream error (incorrect header check)
error: unable to unpack ee3d8abaa95a7395b373892b2593de2f426814e2 header
hint: ee3d8ab unknown type
hint: ee3de99 blob
With your patch:
error: short object ID ee3d is ambiguous
hint: The candidates are:
error: inflate: data stream error (incorrect header check)
error: unable to unpack ee3d8abaa95a7395b373892b2593de2f426814e2 header
error: inflate: data stream error (incorrect header check)
error: unable to unpack ee3d8abaa95a7395b373892b2593de2f426814e2 header
git: object-name.c:364: show_ambiguous_object: Assertion `type == OBJ_TREE || type == OBJ_COMMIT || type == OBJ_BLOB || type == OBJ_TAG' failed.
Aborted
-Peff
