range_ptrinbuf - range check pointer in buffer

       range_ptrinbuf checks if ptr points to buf[0..len-1].

       range_ptrinbuf - range check pointer in buffer

       If the buffer is implausible (buf is NULL or buf+len has an integer overflow), return 0.

       If ptr points to one of buf[0], buf[1], ... or buf[len-1], return 1.

       Otherwise, return 0.

rangecheck(3)

                                                                                               range_ptrinbuf(3)

#include<libowfat/rangecheck.h>

       int range_ptrinbuf(const void* buf,size_t len,const void* ptr);