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

[Stefan Hajnoczi <stefanha@gmail.com>]

On Wed, Oct 02, 2013 at 11:11:05AM -0600, Eric Blake wrote:
> 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.

Yes, please use struct assignment.

Stefan