Sorry about that last post. I forgot that MS never follows published specifications. The ANSI C standard states that malloc() of any memory should either allocate the memory or fail - most implementations of the standard C library return NULL on a call to malloc with 0 as the size.
Calls to realloc() with size as 0 are supposed to free the pointer.
However, MS doesn't follow ANSI at all, anywhere, and since ReactOS is meant to be 100% binary compatable with Windows it should follow the MSDN specs for functions.
DRH