Re: [PATCH v7 1/4] sha1_file.c: support reading from a loose object of unknown type

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 4, 2015, 19:34 UTC
Message-ID: <xmqq7ftrg02b.fsf@gitster.dls.corp.google.com>
In-Reply-To: <1428126162-18987-1-git-send-email-karthik.188@gmail.com>

Karthik Nayak <karthik.188@gmail.com> writes:

Show 9 quoted lines

> @@ -2586,13 +2649,15 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi,
>  			*(oi->disk_sizep) = 0;
>  		if (oi->delta_base_sha1)
>  			hashclr(oi->delta_base_sha1);
> +		if (oi->typename)
> +			strbuf_addstr(oi->typename, typename(co->type));
>  		oi->whence = OI_CACHED;
>  		return 0;
>  	}

Just before the pre-context of this hunk, there is this bit:

	if (oi->typep)
		*(oi->typep) = co->type;

which tells me that the callers of this function is allowed to pass a NULL in oi->typep when they are not interested in the type of the object.

Show 13 quoted lines

>  	if (!find_pack_entry(real, &e)) {
>  		/* Most likely it's a loose object. */
> -		if (!sha1_loose_object_info(real, oi)) {
> +		if (!sha1_loose_object_info(real, oi, flags)) {
>  			oi->whence = OI_LOOSE;
>  			return 0;
>  		}
> @@ -2616,6 +2681,8 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi,
>  		oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
>  					 rtype == OBJ_OFS_DELTA);
>  	}
> +	if (oi->typename)
> +		strbuf_addstr(oi->typename, typename(*oi->typep));

So, it makes me wonder what guarantee we have that this does not dereference a NULL here.