[net.sources] Missing "unique

kwlalonde@watmath.UUCP (Ken Lalonde) (06/17/85)

The batch package I posted to net.sources a while back
made use of unique(), a local system call that returns
a unique number.  If you don't want to change your kernel,
you can use
	long
	unique()
	{
		long time();
		return time(0);
	}
There is a remote possibility that the same value may
be returned to two processes.  We added this to sys/kern_xxx.c:

	/*
	 * Return a unique number.
	 * Usually the time of day, but
	 * with no chance of duplication.
	 */
	unique()
	{
		static long lastuniq = 0;
		register long uniq;

		if (lastuniq == 0)
			lastuniq = time.tv_sec;
		uniq = time.tv_sec;
		if (uniq <= lastuniq)
			uniq = lastuniq + 1;
		u.u_r.r_val1 = uniq;
		lastuniq = uniq;
	}