More time hacks for Windows clock setbacks from UTC to local time.

sensors/slothd/GNUmakefile.in

@@ -12,9 +12,9 @@ SLOTHD_DIR	= unknownclient
 TBLIB		= $(OBJDIR)/lib/libtb/libtb.a
 
 SBIN_SCRIPTS    = sdisrunning sddeploy
-SDPROGS		= sdcollectd slothd
+SDPROGS		= sdcollectd$(EXE) slothd$(EXE)
 
-SYSTEM               := $(shell uname -s)
+SYSTEM          := $(shell uname -s)
 
 include $(OBJDIR)/Makeconf
 
@@ -34,6 +34,7 @@ ifeq ($(SYSTEM),CYGWIN_NT-5.1)
 MLIBS += -liphlpapi
 
 WINCLIENT = idlemon
+WINPROGS = idlemon$(EXE)
 WINCLIENTSRC = idlemon.c
 CVR = /HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows/CurrentVersion/Run
 IDLEKEY = $(CVR)/EmulabIdle
@@ -86,4 +87,4 @@ endif
 control-install:
 
 clean:
-	rm -f *.o $(SDPROGS) *~ core *.core version.c
+	rm -f *.o $(SDPROGS) $(WINPROGS) *~ core *.core version.c

sensors/slothd/idlemon.c

@@ -25,7 +25,7 @@ int main(int argc, char **argv) {
   int ch;
   int debug = 0;
   int input_occurred_fd;
-  time_t last_time = 0;
+  DWORD last_tick = 0;
   
   while ((ch = getopt(argc, argv, "d")) != -1) {
     switch (ch) {
@@ -55,13 +55,19 @@ int main(int argc, char **argv) {
     else {
 
       /* Windows keeps time in millisecond ticks since boot time. */
-      DWORD windows_ticks = GetTickCount() - windows_input.dwTime;
-      time_t windows_time = time(0) - windows_ticks/1000;
-      if (debug)
-	printf("Windows input event time: %s", ctime(&windows_time));
+      DWORD windows_tick = windows_input.dwTime;
+      if (debug) {
+	time_t windows_time = time(0) - (GetTickCount() - windows_tick)/1000;
+	printf("Windows input event tick %d, time: %s", 
+	       windows_tick, ctime(&windows_time));
+      }
       
-      if (windows_time > last_time) {
-	last_time = windows_time;
+      /* Check time in ticks, because they're monotonic.  The clock jumps back
+       * many hours (in the western hemisphere) as NTP changes from UTC time
+       * to local time.
+       */
+      if (windows_tick > last_tick) {
+	last_tick = windows_tick;
 
 	/* It would be nice to use futimes(), but there's not one
 	 * on Cygwin.  Instead, use ftruncate() to set the modtime.

sensors/slothd/slothd.c

@@ -73,7 +73,7 @@ int main(int argc, char **argv) {
 
   int exitcode = -1;
   u_int myabits, span;
-  time_t curtime;
+  time_t curtime, lasttime = 0;
   static SLOTHD_OPTS mopts;
   static SLOTHD_PARAMS mparms;
   static SLOTHD_PACKET mpkt;
@@ -105,6 +105,28 @@ int main(int argc, char **argv) {
       lnotice(build_info);
       for (;;) {
         
+	time(&curtime);
+	if (opts->debug) {
+	  printf("The time is now %s", ctime(&curtime));
+	  fflush(stdout);
+	}
+
+	if (curtime < lasttime) {
+	  /*
+	   * The clock was set back on us, most likely on Windows as NTP
+	   * changed the clock from UTC time to local time.  Set the
+	   * timestamps back by the same amount to compensate.
+	   */
+	  int delta = lasttime - curtime;
+	  parms->startup -= delta;
+	  mparms.lastrpt -= delta;
+	  if (opts->debug) {
+	    printf("The clock was set back by %d seconds.\n\n", delta);
+	    fflush(stdout);
+	  }
+	}
+	lasttime = curtime;
+
         /* Collect current machine stats */
         mparms.cnt++;
         get_load(pkt);
@@ -119,7 +141,7 @@ int main(int argc, char **argv) {
          * 2) Its been over <reg_interval> seconds since the last report
          */
         if ((!opkt->actbits && pkt->actbits) ||
-            (time(&curtime) >=  mparms.lastrpt + mopts.reg_interval) ||
+            (curtime >=  mparms.lastrpt + mopts.reg_interval) ||
             parms->dolast) {
           if (send_pkt(pkt)) {
             mparms.lastrpt = curtime;
@@ -496,14 +518,24 @@ void get_min_tty_idle(SLOTHD_PACKET *pkt) {
 #ifndef __CYGWIN__
       /* The time of last reading keyboard input. */
       time_t tty_time = sb.st_atime;
+      if (opts->debug)
+	printf("Input on %s: %s", parms->ttys[i], ctime(&tty_time));
 #else
-      /* We're modding time tag files Cygwin, not reading them. */
+      /* We're modding time tag files on Cygwin, not reading them. */
       time_t tty_time = sb.st_mtime;
+
+      /* Ignore a time tag from the future when the clock gets set back. */
+      if ( tty_time > time(NULL) ) {
+	if (opts->debug)
+	  printf("Ignored future time on %s: %s", 
+		 parms->ttys[i], ctime(&tty_time));
+	tty_time = mintime;
+      }
 #endif
+      if (opts->debug)
+	printf("Input on %s: %s", parms->ttys[i], ctime(&tty_time));
       if (tty_time > mintime) {
 	mintime = tty_time;
-	if (opts->debug)
-	  printf("Input on %s: %s", parms->ttys[i], ctime(&mintime));
       }
     }
   }