Re: [Xen-devel] [PATCH 06 of 10 v2] libxl: expand the libxl_bitmap API a bit

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2012-06-15 at 18:04 +0100, Dario Faggioli wrote:
> By adding copying and *_is_full/*_is_empty facilities.
> 
> Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> 
> Changes from v1:
>  * now libxl_is_full/empty return 1 if true and 0 if false,
>    as logic (and as requested during review).
> 
> diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
> --- a/tools/libxl/libxl_utils.c
> +++ b/tools/libxl/libxl_utils.c
> @@ -506,6 +506,35 @@ void libxl_bitmap_dispose(libxl_bitmap *
>      free(map->map);
>  }
>  
> +void libxl_bitmap_copy(libxl_ctx *ctx, libxl_bitmap *dptr,
> +                       const libxl_bitmap *sptr)
> +{
> +    int sz;
> +
> +    sz = dptr->size = sptr->size;
> +    memcpy(dptr->map, sptr->map, sz * sizeof(*dptr->map));

I think you need either some checks/asserts on the two relative sizes or
a reallocation of the destination map. Otherwise you risk an overflow.

Perhaps a simple assert (i.e. make it the callers problem) would be ok?

> +}
> +
> +int libxl_bitmap_is_full(const libxl_bitmap *bitmap)
> +{
> +    int i;
> +
> +    for (i = 0; i < bitmap->size; i++)
> +        if (bitmap->map[i] != (uint8_t)-1)
> +            return 0;
> +   return 1;
> +}
> +
> +int libxl_bitmap_is_empty(const libxl_bitmap *bitmap)
> +{
> +    int i;
> +
> +    for (i = 0; i < bitmap->size; i++)
> +        if (bitmap->map[i])
> +            return 0;
> +    return 1;
> +}
> +
>  int libxl_bitmap_test(const libxl_bitmap *bitmap, int bit)
>  {
>      if (bit >= bitmap->size * 8)
> diff --git a/tools/libxl/libxl_utils.h b/tools/libxl/libxl_utils.h
> --- a/tools/libxl/libxl_utils.h
> +++ b/tools/libxl/libxl_utils.h
> @@ -66,6 +66,10 @@ int libxl_vdev_to_device_disk(libxl_ctx 
>  int libxl_bitmap_alloc(libxl_ctx *ctx, libxl_bitmap *bitmap, int n_bits);
>      /* Allocated bimap is from malloc, libxl_bitmap_dispose() to be
>       * called by the application when done. */
> +void libxl_bitmap_copy(libxl_ctx *ctx, libxl_bitmap *dptr,
> +                       const libxl_bitmap *sptr);
> +int libxl_bitmap_is_full(const libxl_bitmap *bitmap);
> +int libxl_bitmap_is_empty(const libxl_bitmap *bitmap);
>  int libxl_bitmap_test(const libxl_bitmap *bitmap, int bit);
>  void libxl_bitmap_set(libxl_bitmap *bitmap, int bit);
>  void libxl_bitmap_reset(libxl_bitmap *bitmap, int bit);



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