shf_fillbuf
static int shf_fillbuf(struct shf *);
(shf_fillbuf(shf) == EOF || shf->rnleft == 0))
if (shf_fillbuf(shf) == EOF)
if (shf->rnleft == 0 && (shf_fillbuf(shf) == EOF || shf->rnleft == 0))