From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 25 Jul 2008 18:15:47 GMT
Subject: Re: [PATCH] index-pack: correctly initialize appended objects
Message-ID: <7v4p6du8x8.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <alpine.LFD.1.10.0807250751220.9968@xanadu.home>

Nicolas Pitre <nico@cam.org> writes:

> On Fri, 25 Jul 2008, Johannes Schindelin wrote:
>
>> Hi,
>> 
>> On Thu, 24 Jul 2008, Junio C Hamano wrote:
>> 
>> > 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?
>> 
>> >From staring at the code, I thought that real_type was set in 
>> resolve_delta(), but I may be wrong.
>> 
>> The safer thing would be to set it, but I am not quite sure if we can use 
>> "type" directly, or if type can be "delta" for an object that is used to 
>> complete the pack, and therefore stored as a non-delta.
>
> Objects to complete the pack are always non delta, so the type and 
> real_type should be the same.  However that shouldn't matter since at 
> that point the object array is not walked anymore, at least not for 
> appended objects, and therefore initializing the type at that point is 
> redundant.

Thanks.  Here is what I committed.

commit 72de2883bd7d4ceda05f107826c7607c594de965
Author: Björn Steinbrink <B.Steinbrink@gmx.de>
Date:   Thu Jul 24 18:32:00 2008 +0100

    index-pack.c: correctly initialize appended objects
    
    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, and will be read back again by get_data_from_pack().  For this
    to work, the fields in object_entry structure need to be initialized
    properly.
    
    Noticed by Pierre Habouzit.
    
    Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de>
    Acked-by: Nicolas Pitre <nico@cam.org>
    Acked-by: Shawn O. Pearce <spearce@spearce.org>
    Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/index-pack.c b/index-pack.c
index c359f8c..7d5344a 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -698,6 +698,10 @@ 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].size = size;
+	obj[0].hdr_size = n;
+	obj[0].type = type;
+	obj[0].real_type = type;
 	obj[1].idx.offset = obj[0].idx.offset + n;
 	obj[1].idx.offset += write_compressed(output_fd, buf, size, &obj[0].idx.crc32);
 	hashcpy(obj->idx.sha1, sha1);