check_roffset
if ((r = check_roffset(buf, offset, 8, &p)) != 0)
if ((r = check_roffset(buf, offset, 4, &p)) != 0)
if ((r = check_roffset(buf, offset, 2, &p)) != 0)
if ((r = check_roffset(buf, offset, 1, &p)) != 0)