Subject: Re: [PATCH 06/13] fsck: stop using object_info->type_name strbuf

From: Junio C Hamano <[email-masked]>
Date: Mon, 19 May 2025 07:26:05 -0700

Jeff King <[email-masked]> writes:

> So we can simplify things by bailing immediately in read_loose_object()
> when we encounter an unknown type. This has a few user-visible effects:
>
>   a. Instead of producing a single line of error output like this:
>
>        error: 26ed13ce3564fbbb44e35bde42c7da717ea004a6: object is of unknown type 'bogus': .git/objects/26/ed13ce3564fbbb44e35bde42c7da717ea004a6
>
>      we'll now issue two lines (the first from read_loose_object() when
>      we see the unparsable header, and the second from the fsck code,
>      since we couldn't read the object):
>
>        error: unable to parse type from header 'bogus 4' of .git/objects/26/ed13ce3564fbbb44e35bde42c7da717ea004a6
>        error: 26ed13ce3564fbbb44e35bde42c7da717ea004a6: object corrupt or missing: .git/objects/26/ed13ce3564fbbb44e35bde42c7da717ea004a6

Just curious; is the difference between 'bogus' and 'bogus 4'
significant in the above examples?

>
>      This is a little more verbose, but this sort of error should be
>      rare (such objects are almost impossible to work with, and cannot
>      be transferred between repositories as they are not representable
>      in packfiles). And as a bonus, reporting the broken header in full
>      could help with debugging other cases (e.g., a header like "blob
>      xyzzy\0" would fail in parsing the size, but previously we'd not
>      have showed the offending bytes).

Yup, I do not think anybody minds the message that has overly long
object name toward the end, instead of the beginning, of line,
either.

>   b. An object with an unknown type will be reported as corrupt, without
>      actually doing a hash check. Again, I think this is unlikely to
>      matter in practice since such objects are totally unusable.

Agreed.

> We'll update one fsck test to match the new error strings. And we can
> remove another test that covered the case of an object with an unknown
> type _and_ a hash corruption. Since we'll skip the hash check now in
> this case, the test is no longer interesting.
>
> Signed-off-by: Jeff King <[email-masked]>
> ---
>  builtin/fsck.c  | 13 ++-----------
>  object-file.c   | 12 +++++++++---
>  t/t1450-fsck.sh | 29 +++--------------------------
>  3 files changed, 14 insertions(+), 40 deletions(-)

Pleasant.

Thanks.