offset = pgsize * pageno + relative;
offset = (off_t)pgsize * pageno + relative; if (isrewind) offset = -offset;
__os_seek(fd, pgsize, pageno, relative, whence)	int fd;	size_t pgsize;	db_pgno_t pageno;	u_long relative;	int whence;{	off_t offset;	offset = pgsize * pageno + relative;	return (lseek(fd, offset, whence) == -1 ? errno : 0);}