[PATCH:libX11 07/12] Avoid memory leak/corruption if realloc fails in Xregion.h:MEMCHECK macro

[Matthieu Herrb]

On Sat, Aug 10, 2013 at 01:55:04PM -0700, Alan Coopersmith wrote:
> Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>

I'm wondering here if firstrect() shouldn't be free()'d when Xrealloc
fails. I can't tell from reading the code what will happen if Xrealloc
fails (since most of the callers are void functions that don't have a
way to propagate the error). 

> ---
>  include/X11/Xregion.h |    7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/include/X11/Xregion.h b/include/X11/Xregion.h
> index c25d70b..cf10f86 100644
> --- a/include/X11/Xregion.h
> +++ b/include/X11/Xregion.h
> @@ -112,10 +112,11 @@ typedef struct _XRegion {
>   */
>  #define MEMCHECK(reg, rect, firstrect){\
>          if ((reg)->numRects >= ((reg)->size - 1)){\
> -          (firstrect) = (BOX *) Xrealloc \
> -          ((char *)(firstrect), (unsigned) (2 * (sizeof(BOX)) * ((reg)->size)));\
> -          if ((firstrect) == 0)\
> +          BoxPtr tmpRect = Xrealloc ((firstrect), \
> +                                     (2 * (sizeof(BOX)) * ((reg)->size))); \
> +          if (tmpRect == NULL) \
>              return(0);\
> +          (firstrect) = tmpRect; \
>            (reg)->size *= 2;\
>            (rect) = &(firstrect)[(reg)->numRects];\
>           }\
> -- 
> 1.7.9.2
> 
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-- 
Matthieu Herrb