Re: [PATCH] index-pack: correctly initialize appended objects

[Junio C Hamano <gitster@pobox.com>]

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

> From: Björn Steinbrink <B.Steinbrink@gmx.de>
>
> When index-pack completes a thin pack it appends objects to the pack.  
> Since the commit 92392b4(index-pack: Honor core.deltaBaseCacheLimit when 
> resolving deltas) such an object can be pruned in case of memory
> pressure.
>
> To be able to re-read the object later, a few more fields have to be set.
>
> Noticed by Pierre Habouzit.
>
> Hopefully-signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de>
> Hopefully-reviewed-and-signed-off-by: Nicolas Pitre <nico@cam.org>, 
>
> --
> 	Nico could you have a quick look?  (I would ask Shawn, but I know 
> 	that he is pretty busy with real world issues.)

Reading get_data_from_pack(), it does rely on hdr_size, idx.offset and
idx.offset of the next entry to be set correctly.  The function does not
seem to use type (which the patch is also setting) nor real_type (which
the patch does not set).

However, the code checks objects[nth].real_type all over the place in the
code.  Doesn't the lack of real_type assignment in append_obj_to_pack()
affect them in  any way?

> diff --git a/index-pack.c b/index-pack.c
> index ac20a46..33ba8ef 100644
> --- a/index-pack.c
> +++ b/index-pack.c
> @@ -699,6 +699,9 @@ static struct object_entry *append_obj_to_pack(
>  	write_or_die(output_fd, header, n);
>  	obj[0].idx.crc32 = crc32(0, Z_NULL, 0);
>  	obj[0].idx.crc32 = crc32(obj[0].idx.crc32, header, n);
> +	obj[0].hdr_size = n;
> +	obj[0].type = type;
> +	obj[0].size = size;
>  	obj[1].idx.offset = obj[0].idx.offset + n;
>  	obj[1].idx.offset += write_compressed(output_fd, buf, size, &obj[0].idx.crc32);