Refine the code to make it more safely.

Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Jaben Carsey <Jaben.carsey@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13696 6f19259b-4bc3-4df7-8a09-765794883524
1 file changed