Add CLOCK_UPTIME to clock_gettime(2) reporting the current

uptime measured in SI seconds.

Sponsored by:	TCP/IP Optimization Fundraise 2005

sys/kern/kern_time.c

@@ -224,6 +224,7 @@ kern_clock_gettime(struct thread *td, clockid_t clock_id, struct timespec *ats)
 		TIMEVAL_TO_TIMESPEC(&user, ats);
 		break;
 	case CLOCK_MONOTONIC:
+	case CLOCK_UPTIME:
 		nanouptime(ats);
 		break;
 	default:
@@ -307,6 +308,7 @@ kern_clock_getres(struct thread *td, clockid_t clock_id, struct timespec *ts)
 	switch (clock_id) {
 	case CLOCK_REALTIME:
 	case CLOCK_MONOTONIC:
+	case CLOCK_UPTIME:
 		/*
 		 * Round up the result of the division cheaply by adding 1.
 		 * Rounding up is especially important if rounding down

sys/sys/time.h

@@ -238,6 +238,7 @@ struct clockinfo {
 #define CLOCK_VIRTUAL	1
 #define CLOCK_PROF	2
 #define CLOCK_MONOTONIC	4
+#define CLOCK_UPTIME	5
 #endif
 
 #ifndef TIMER_ABSTIME