2_GB_File_Size_Macro

   The C RTL provides support for compiling applications to use file
   sizes and offsets that are 2 GB and larger. This is accomplished
   by allowing file offsets of 64-bit integers.

   The fseeko and ftello functions, which have the same behavior
   as fseek and ftell, accept or return values of type off_t, which
   allows for a 64-bit variant of off_t to be used.

   C RTL functions lseek, mmap, ftuncate, truncate, stat, fstat, and
   ftw can also accommodate a 64-bit file offset.

   The new 64-bit interfaces can be selected at compile time by
   defining the _LARGEFILE feature macro.