hwclock: size optimizations

libbb/time.c: new file, introducing monotonic_us()
pscan, traceroute, arping: use it instead of gettimeofday
ping, zcip: TODO

function                                             old     new   delta
monotonic_us                                           -      89     +89
find_pair                                            164     180     +16
.rodata                                           129747  129763     +16
refresh                                             1144    1152      +8
............
timeout                                                8       4      -4
static.start                                           8       4      -4
last                                                   8       4      -4
parse_conf                                          1303    1284     -19
time_main                                           1149    1124     -25
gettimeofday_us                                       39       -     -39
arping_main                                         2042    1969     -73
hwclock_main                                         594     501     -93
catcher                                              485     380    -105
traceroute_main                                     4300    4117    -183
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 8/11 up/down: 157/-562)        Total: -405 bytes

1 files changed, 9 insertions, 19 deletions

diff --git a/networking/pscan.c b/networking/pscan.c
index 10bf3b6..9fa6993 100644
--- a/networking/pscan.c
+++ b/networking/pscan.c
@@ -17,19 +17,6 @@
 #define DERR(...) ((void)0)
 #endif
 
-/* return time in usec */
-// TODO: move to libbb and use in traceroute, zcip, arping etc
-// (maybe also use absolute monotonic clock - no time warps
-// due to admin resetting date/time?)
-static unsigned gettimeofday_us(void)
-{
-	struct timeval now;
-	
-	if (gettimeofday(&now, NULL))
-		return 0;
-	return (now.tv_sec * 1000000 + now.tv_usec);
-}
-
 static const char *port_name(unsigned port)
 {
 	struct servent *server;
@@ -40,6 +27,9 @@ static const char *port_name(unsigned port)
 	return "unknown";
 }
 
+/* We don't expect to see 1000+ seconds delay, unsigned is enough */
+#define MONOTONIC_US() ((unsigned)monotonic_us())
+
 int pscan_main(int argc, char **argv);
 int pscan_main(int argc, char **argv)
 {
@@ -91,7 +81,7 @@ int pscan_main(int argc, char **argv)
 		/* Nonblocking connect typically "fails" with errno == EINPROGRESS */
 		ndelay_on(s);
 		DMSG("connect to port %u", port);
-		start = gettimeofday_us();
+		start = MONOTONIC_US();
 		if (connect(s, &lsap->sa, lsap->len) == 0) {
 			/* Unlikely, for me even localhost fails :) */
 			DMSG("connect succeeded");
@@ -110,15 +100,15 @@ int pscan_main(int argc, char **argv)
 				closed_ports++;
 				break;
 			}
-			DERR("port %u errno %d @%u", port, errno, gettimeofday_us() - start);
-			if ((gettimeofday_us() - start) > rtt_4)
+			DERR("port %u errno %d @%u", port, errno, MONOTONIC_US() - start);
+			if ((MONOTONIC_US() - start) > rtt_4)
 				break;
 			/* Can sleep (much) longer than specified delay.
 			 * We check rtt BEFORE we usleep, otherwise
 			 * on localhost we'll do zero writes done (!)
 			 * before we exceed (rather small) rtt */
 			usleep(rtt_4/8);
-			DMSG("write to port %u @%u", port, gettimeofday_us() - start);
+			DMSG("write to port %u @%u", port, MONOTONIC_US() - start);
 			if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
  open:
 				open_ports++;
@@ -126,13 +116,13 @@ int pscan_main(int argc, char **argv)
 				break;
 			}
 		}
-		DMSG("out of loop @%u", gettimeofday_us() - start);
+		DMSG("out of loop @%u", MONOTONIC_US() - start);
 
 		/* Estimate new rtt - we don't want to wait entire timeout
 		 * for each port. *4 allows for rise in net delay.
 		 * We increase rtt quickly (*4), decrease slowly (4/8 == 1/2)
 		 * because we don't want to accidentally miss ports. */
-		rtt_4 = (gettimeofday_us() - start) * 4;
+		rtt_4 = (MONOTONIC_US() - start) * 4;
 		if (rtt_4 < min_rtt)
 			rtt_4 = min_rtt;
 		if (rtt_4 > timeout)