Re: pack-objects: Fix segfault when object count is less than thread count

> On Mon, 21 Jan 2008, Sergey Vlasov wrote:
> 
> > When partitioning the work amongst threads, dividing the number of
> > objects by the number of threads may return 0 when there are less
> > objects than threads; this will cause the subsequent code to segfault
> > when accessing list[sub_size-1].  Fix this by ensuring that sub_size
> > is not zero if there is at least one object to process.
> 
> No.  Forcing one object in a thread is counter productive since it won't 
> have anything to delta against.  Instead, the thread should be allowed 
> to have zero objects and let the other threads have more.
> 
> This patch would be a proper fix:
> 
> diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
> index ec10238..d3efeff 100644
> --- a/builtin-pack-objects.c
> +++ b/builtin-pack-objects.c
> @@ -1672,7 +1672,8 @@ static void ll_find_deltas(struct object_entry **list, unsigned list_size,
>  		p[i].data_ready = 0;
>  
>  		/* try to split chunks on "path" boundaries */
> -		while (sub_size < list_size && list[sub_size]->hash &&
> +		while (sub_size && sub_size < list_size &&
> +		       list[sub_size]->hash &&
>  		       list[sub_size]->hash == list[sub_size-1]->hash)
>  			sub_size++;