Re: [PATCH 1/1] MdePkg/Base.h: Implement BASE_CR() via OFFSET_OF().

["Gao, Liming" <liming.gao@intel.com>]

The change is good. Reviewed-by: Liming Gao <liming.gao@intel.com>

>-----Original Message-----
>From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
>Marvin H?user
>Sent: Thursday, November 01, 2018 4:09 AM
>To: edk2-devel@lists.01.org
>Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Gao, Liming
><liming.gao@intel.com>
>Subject: [edk2] [PATCH 1/1] MdePkg/Base.h: Implement BASE_CR() via
>OFFSET_OF().
>
>Replace the current NULL pointer dereference to retrieve Field's
>offset with a call to OFFSET_OF().  This is implemented via
>__builtin_offsetof for GCC and Clang, which eliminates UB caught by
>Clang UndefinedBehaviorSanitizer.
>
>Contributed-under: TianoCore Contribution Agreement 1.1
>Signed-off-by: Marvin Haeuser <Marvin.Haeuser@outlook.com>
>---
> MdePkg/Include/Base.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/MdePkg/Include/Base.h b/MdePkg/Include/Base.h
>index 523192fd79fc..bc877d8125a5 100644
>--- a/MdePkg/Include/Base.h
>+++ b/MdePkg/Include/Base.h
>@@ -869,7 +869,7 @@ typedef UINTN  *BASE_LIST;
>   @return  A pointer to the structure from one of it's elements.
>
> **/
>-#define BASE_CR(Record, TYPE, Field)  ((TYPE *) ((CHAR8 *) (Record) -
>(CHAR8 *) &(((TYPE *) 0)->Field)))
>+#define BASE_CR(Record, TYPE, Field)  ((TYPE *) ((CHAR8 *) (Record) -
>OFFSET_OF (TYPE, Field)))
>
> /**
>   Rounds a value up to the next boundary using a specified alignment.
>--
>2.19.1.windows.1
>
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