Subject: Re: [PATCH v2 4/4] object-file: fix a unpack_loose_header() regression in 3b6a8db3b03

From: Junio C Hamano <[email-masked]>
Date: Thu, 12 May 2022 16:39:12 -0700

Junio C Hamano <[email-masked]> writes:

> diff --git a/object-file.c b/object-file.c
> index 5ffbf3d4fd..b5d1d12b68 100644
> --- a/object-file.c
> +++ b/object-file.c
> @@ -2623,8 +2623,12 @@ int read_loose_object(const char *path,
>  		goto out;
>  	}
>  
> -	if (unpack_loose_header(&stream, map, mapsize, hdr, sizeof(hdr),
> -				NULL) < 0) {
> +	switch (unpack_loose_header(&stream, map, mapsize, hdr, sizeof(hdr),
> +				    NULL)) {
> +	case ULHR_OK:
> +		break;
> +	case ULHR_BAD:
> +	case ULHR_TOO_LONG:
>  		error(_("unable to unpack header of %s"), path);
>  		goto out;
>  	}

Regarding this hunk, since we only care about a single "did we get
any error, or did we unpack OK" bit, I think this should be more
like

	if (unpack_loose_header(...) != ULHR_OK) {
		error(_("unable to..."), path);
		goto out;
	}

It is true, as Ævar mentioned, that there is another place in the
same file that uses switch() in loose_object_info(), and it should
remain to be switch() on the returned enum because it wants to
behave differnetly depending on the kind of error it gets.  But that
is not a reason to make this part that only cares about a single
"did it fail?" into a switch and force future developers to add a
useless case arm.

I left it there as posted in the previous round because I was too
lazy ;-) and also it is something we can clean up with a follow up
patch outside the series.  As my today's focus has been to reduce
the number of topics waiting for a reroll, I'd rather leave things
that are not outright broken but needs clean up as they are for the
sake of expediency.

Thanks.