Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends

[malc]

On Mon, 7 Dec 2009, Anthony Liguori wrote:

> Markus Armbruster wrote:
> > Commit a7d27b53 made zero-sized allocations a fatal error, deviating
> > from ISO C's malloc() & friends.  Revert that, but take care never to
> > return a null pointer, like malloc() & friends may do (it's
> > implementation defined), because that's another source of bugs.
> >   
> 
> While it's always fun to argue about standards interpretation, I wanted to
> capture some action items from the discussion that I think there is agreement
> about.  Since I want to make changes for 0.12, I think it would be best to try
> and settle these now so we can do this before -rc2.
> 
> For 0.12.0-rc2:
> 
> I will send out a patch tonight or tomorrow changing qemu_malloc() to return
> malloc(1) when size=0 only for production builds (via --enable-zero-mallocs).
> Development trees will maintain their current behavior.
> 
> For 0.13:
> 
> Someone (Marcus?) will introduce four new allocation functions.
> 
> type *qemu_new(type, n_types);
> type *qemu_new0(type, n_types);
> 
> type *qemu_renew(type, mem, n_types);
> type *qemu_renew0(type, mem, n_types);
> 
> NB: The names are borrowed from glib.  I'm not tied to them.
> 
> Will do our best to convert old code to use these functions where ever
> possible.  New code will be required to use these functions unless not
> possible.  n_types==0 is valid.  sizeof(type)==0 is valid.  Both circumstances
> return a unique non-NULL pointer.  If memory allocation fails, execution will
> abort.
> 
> The existing qemu_malloc() will maintain it's current behavior (with the
> exception of the relaxed size==0 assertion for production releases).
> 
> Does anyone object to this moving forward?

Yeah, i object to the split production/development qemu_malloc[z].

-- 
mailto:address@hidden