Description

   If ptr is the NULL pointer, the behavior of the realloc function
   is identical to the malloc function.

   The contents of the area are unchanged up to the lesser of the
   old and new sizes. The ANSI C Standard states that, "If the
   new size is larger than the old size, the value of the newly
   allocated portion of memory is indeterminate." For compatibility
   with old implementations, VSI C initializes the newly
   allocated memory to 0.

   For efficiency, the previous actual allocation could have been
   larger than the requested size. If it was allocated with malloc,
   the value of the portion of memory between the previous requested
   allocation and the actual allocation is indeterminate. If it was
   allocated with calloc, that same memory was initialized to 0. If
   your application relies on realloc initializing memory to 0, then
   use calloc instead of malloc to perform the initial allocation.
   The maximum amount of memory allocated at once is limited to
   0xFFFFD000.

   See also free, cfree, calloc, and malloc.