Don't return data length if not requested

reactos/lib/advapi32/reg

diff -u -r1.57 -r1.58
--- reg.c	13 Sep 2004 14:42:37 -0000	1.57
+++ reg.c	28 Sep 2004 20:40:15 -0000	1.58
@@ -1,4 +1,4 @@

-/* $Id: reg.c,v 1.57 2004/09/13 14:42:37 ekohl Exp $

+/* $Id: reg.c,v 1.58 2004/09/28 20:40:15 gvg Exp $

  *
  * COPYRIGHT:       See COPYING in the top level directory
  * PROJECT:         ReactOS system libraries

@@ -1444,7 +1444,10 @@

 	      *lpcbValueName = (DWORD)(ValueInfo->Basic.NameLength / sizeof(WCHAR));
 	      lpValueName[*lpcbValueName] = 0;
 	    }

-          *lpcbData = (DWORD)ValueInfo->Full.DataLength;

+	  if (NULL != lpcbData)
+	    {
+	      *lpcbData = (DWORD)ValueInfo->Full.DataLength;
+	    }

 	}
 
       if (ErrorCode == ERROR_SUCCESS && lpType != NULL)