#include <sys/_types/_seek_set.h>
sys/_types/_seek_set.h
macroSEEK_HOLE
#define SEEK_HOLE 3
set file offset to the start of the next hole greater than or equal to the supplied offset
macroSEEK_DATA
#define SEEK_DATA 4
set file offset to the start of the next non-hole file region greater than or equal to the supplied offset