Re: [Qemu-devel] [PATCH] Introduce QEMU_NEW()

[Richard W.M. Jones]

On Mon, Jul 25, 2011 at 11:51:12AM +0300, Avi Kivity wrote:
> qemu_malloc() is type-unsafe as it returns a void pointer.  Introduce
> QEMU_NEW() (and QEMU_NEWZ()), which return the correct type.
> 
> Signed-off-by: Avi Kivity <address@hidden>
> ---
> 
> This is part of my memory API patchset, but doesn't really belong there.
> 
>  qemu-common.h |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/qemu-common.h b/qemu-common.h
> index ba55719..66effa3 100644
> --- a/qemu-common.h
> +++ b/qemu-common.h
> @@ -186,6 +186,9 @@ void qemu_free(void *ptr);
>  char *qemu_strdup(const char *str);
>  char *qemu_strndup(const char *str, size_t size);
>  
> +#define QEMU_NEW(type) ((type *)(qemu_malloc(sizeof(type))))
> +#define QEMU_NEWZ(type) ((type *)(qemu_mallocz(sizeof(type))))
> +
>  void qemu_mutex_lock_iothread(void);
>  void qemu_mutex_unlock_iothread(void);

FYI libvirt have been doing something similar, perhaps even more
far-reaching:

http://libvirt.org/hacking.html#memalloc

http://libvirt.org/git/?p=libvirt.git;a=blob;f=src/util/memory.h;hb=HEAD

The libvirt versions are designed to catch errors in situations such
as:

 - trying to allocate zero-sized objects when the underlying malloc
   returns NULL for zero-sized objects

 - trying to allocate N * M-sized objects when N * M overflows

 - realloc fails, don't forget the original pointer

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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