Re: [Qemu-devel] [PATCHv3 20/20] block/raw: copy BlockLimits on raw_open

[Eric Blake <eblake@redhat.com>]

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On 09/24/2013 07:35 AM, Peter Lieven wrote:
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  block/raw_bsd.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/block/raw_bsd.c b/block/raw_bsd.c
> index 8dc7bba..7af26ad 100644
> --- a/block/raw_bsd.c
> +++ b/block/raw_bsd.c
> @@ -159,6 +159,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
>                      Error **errp)
>  {
>      bs->sg = bs->file->sg;
> +    memcpy(&bs->bl, &bs->file->bl, sizeof(struct BlockLimits));

Personally, I think that sizeof(var) is more robust, because if the
declaration of var is ever changed, you don't have to remember to also
touch up the memcpy.  As in:

memcpy(&bs->bl, &bs->file->bl, sizeof(bs->bl));

But there's plenty of examples of sizeof(type) in the codebase even when
a var is handy, so you are not alone, and that's not a reason for me to
request a respin.

On the other hand, why use memcpy() at all?

bs->bl = bs->file->bl;

should do the same trick, with less typing.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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