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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently
Date: Tue, 2 Jun 2009 21:04:54 +0100
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To: David Turner <digit@google.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Jean-Christophe Dubois <jcd@tribudubois.net>, qemu-devel@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>

On Tuesday 02 June 2009, David Turner wrote:
> On Tue, Jun 2, 2009 at 8:13 PM, Paul Brook <paul@codesourcery.com> wrote:
> > > >  QEMU_NEW_ARRAY(ptr, ...);
> > > >
> > > > instead of
> > > >
> > > >  ptr = QEMU_NEW_ARRAY(...);
> > > >
> > > > then.  I don't see another easy way to get the automagic sizeof(*ptr)
> > > > stuff done though.
> > >
> > > The first version will extract the item size automatically for you,
> >
> > making
> >
> > > it less likely that you screw things in the second version's parameter
> > > list.
> >
> > Not if you do it properly it won't.
>
> Very frankly I don't see your point.

My point is that

#define QEMU_NEW(type) ((type *)qemu_malloc(sizeof(type)))
  foo *ptr = QEMU_NEW(foo);

is just as safe as

#define QEMU_NEW(ptr) (ptr) = qemu_malloc(sizeof(*(ptr)))
  foo *ptr;
  QEMU_NEW(ptr);

Because the compiler will catch the type mismatch.

Paul