The new version of the daylight time saving support. This time it works

for any change of the time zone offset from GMT. To enable use the
option -s.

3 files changed, 182 insertions, 5 deletions

diff --git a/usr.sbin/cron/cron/cron.8 b/usr.sbin/cron/cron/cron.8
index ec66af4..02d3aaf 100644
--- a/usr.sbin/cron/cron/cron.8
+++ b/usr.sbin/cron/cron/cron.8
@@ -26,6 +26,12 @@
 .Sh SYNOPSIS
 .Nm
 .Oo
+.Fl s
+.Oc
+.Oo
+.Fl o
+.Oc
+.Oo
 .Fl x
 .Ar debugflag Ns Op , Ns Ar ...
 .Oc
@@ -71,6 +77,51 @@ need not be restarted whenever a crontab file is modified.  Note that the
 .Xr crontab 1
 command updates the modtime of the spool directory whenever it changes a
 crontab.
+.Pp
+Available options:
+.Bl -tag -width indent
+.It Fl s
+Enable special handling of situations when the GMT offset of the local
+timezone changes, such as the switches between the standard time and
+daylight saving time.
+.Pp
+The jobs run during the GMT offset changes time as 
+intuitively expected. If a job falls into a time interval that disappears 
+(for example, during the switch from
+standard time) to daylight saving time or is
+duplicated (for example, during the reverse switch), then it's handled
+in one of two ways:
+.Pp
+The first case is for the jobs that run every at hour of a time interval
+overlapping with the disappearing or duplicated interval.
+In other words, if the job had run within one hour before the GMT offset change
+(and cron was not restarted nor the 
+.Xr crontab 5
+changed after that)
+or would run after the change at the next hour.
+They work as always, skip the skipped time or run in the added
+time as usual. 
+.Pp
+The second case is for the jobs that run less frequently.
+They are executed exactly once, they are not skipped nor
+executed twice (unless cron is restarted or the user's
+.Xr crontab 5
+is changed during such a time interval). If an interval disappears
+due to  the GMT offset change, such jobs are
+executed at the same absolute point of time as they would be in the 
+old time zone. For example, if exactly one hour disappears, this 
+point would be during the next hour at the first minute that is 
+specified for them in
+.Xr crontab 5 .
+.It Fl o
+Disable the special handling of situations when the GMT offset of the local
+timezone changes, to be compatible with the old (default) behavior.
+If both options
+.Fl o
+and
+.Fl s
+are specified, the option specified last wins.
+.El
 .Sh SEE ALSO
 .Xr crontab 1 ,
 .Xr crontab 5 
diff --git a/usr.sbin/cron/cron/cron.c b/usr.sbin/cron/cron/cron.c
index 8889b72..5131645 100644
--- a/usr.sbin/cron/cron/cron.c
+++ b/usr.sbin/cron/cron/cron.c
@@ -36,19 +36,22 @@ static	void	usage __P((void)),
 		run_reboot_jobs __P((cron_db *)),
 		cron_tick __P((cron_db *)),
 		cron_sync __P((void)),
-		cron_sleep __P((void)),
+		cron_sleep __P((cron_db *)),
+		cron_clean __P((cron_db *)),
 #ifdef USE_SIGCHLD
 		sigchld_handler __P((int)),
 #endif
 		sighup_handler __P((int)),
 		parse_args __P((int c, char *v[]));
 
+static time_t	last_time = 0;
+static int	dst_enabled = 0;
 
 static void
 usage() {
     char **dflags;
 
-	fprintf(stderr, "usage: cron [-x debugflag[,...]]\n");
+	fprintf(stderr, "usage: cron [-s] [-o] [-x debugflag[,...]]\n");
 	fprintf(stderr, "\ndebugflags: ");
 
         for(dflags = DebugFlagNames; *dflags; dflags++) {
@@ -117,7 +120,7 @@ main(argc, argv)
 # if DEBUGGING
 	    /* if (!(DebugFlags & DTEST)) */
 # endif /*DEBUGGING*/
-			cron_sleep();
+			cron_sleep(&database);
 
 		load_database(&database);
 
@@ -154,6 +157,11 @@ static void
 cron_tick(db)
 	cron_db	*db;
 {
+	static struct tm	lasttm;
+	static time_t	diff = 0, /* time difference in seconds from the last offset change */
+		difflimit = 0; /* end point for the time zone correction */
+	struct tm	otztm; /* time in the old time zone */
+	int		otzminute, otzhour, otzdom, otzmonth, otzdow;
  	register struct tm	*tm = localtime(&TargetTime);
 	register int		minute, hour, dom, month, dow;
 	register user		*u;
@@ -170,6 +178,65 @@ cron_tick(db)
 	Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d)\n",
 		getpid(), minute, hour, dom, month, dow))
 
+	if (dst_enabled && last_time != 0 
+	&& TargetTime > last_time /* exclude stepping back */
+	&& tm->tm_gmtoff != lasttm.tm_gmtoff ) {
+
+		diff = tm->tm_gmtoff - lasttm.tm_gmtoff;
+
+		if ( diff > 0 ) { /* ST->DST */
+			/* mark jobs for an earlier run */
+			difflimit = TargetTime + diff;
+			for (u = db->head;  u != NULL;  u = u->next) {
+				for (e = u->crontab;  e != NULL;  e = e->next) {
+					e->flags &= ~NOT_UNTIL;
+					if ( e->lastrun >= TargetTime )
+						e->lastrun = 0;
+					/* not include the ends of hourly ranges */
+					if ( e->lastrun < TargetTime - 3600 )
+						e->flags |= RUN_AT;
+					else
+						e->flags &= ~RUN_AT;
+				}
+			}
+		} else { /* diff < 0 : DST->ST */
+			/* mark jobs for skipping */
+			difflimit = TargetTime - diff;
+			for (u = db->head;  u != NULL;  u = u->next) {
+				for (e = u->crontab;  e != NULL;  e = e->next) {
+					e->flags |= NOT_UNTIL;
+					e->flags &= ~RUN_AT;
+				}
+			}
+		}
+	}
+
+	if (diff != 0) {
+		/* if the time was reset of the end of special zone is reached */
+		if (last_time == 0 || TargetTime >= difflimit) {
+			/* disable the TZ switch checks */
+			diff = 0;
+			difflimit = 0;
+			for (u = db->head;  u != NULL;  u = u->next) {
+				for (e = u->crontab;  e != NULL;  e = e->next) {
+					e->flags &= ~(RUN_AT|NOT_UNTIL);
+				}
+			}
+		} else {
+			/* get the time in the old time zone */
+			time_t difftime = TargetTime + tm->tm_gmtoff - diff;
+			gmtime_r(&difftime, &otztm);
+
+			/* make 0-based values out of these so we can use them as indicies
+			 */
+			otzminute = otztm.tm_min -FIRST_MINUTE;
+			otzhour = otztm.tm_hour -FIRST_HOUR;
+			otzdom = otztm.tm_mday -FIRST_DOM;
+			otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
+			otzdow = otztm.tm_wday -FIRST_DOW;
+		}
+	}
+
 	/* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 	 * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 	 * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
@@ -181,6 +248,27 @@ cron_tick(db)
 			Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 					  env_get("LOGNAME", e->envp),
 					  e->uid, e->gid, e->cmd))
+
+			if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
+				if (bit_test(e->minute, otzminute)
+				 && bit_test(e->hour, otzhour)
+				 && bit_test(e->month, otzmonth)
+				 && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
+					  ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
+					  : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
+					)
+				   ) {
+					if ( e->flags & RUN_AT ) {
+						e->flags &= ~RUN_AT;
+						e->lastrun = TargetTime;
+						job_add(e, u);
+						continue;
+					} else 
+						e->flags &= ~NOT_UNTIL;
+				} else if ( e->flags & NOT_UNTIL )
+					continue;
+			}
+
 			if (bit_test(e->minute, minute)
 			 && bit_test(e->hour, hour)
 			 && bit_test(e->month, month)
@@ -189,10 +277,15 @@ cron_tick(db)
 			      : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 			    )
 			   ) {
+				e->flags &= ~RUN_AT;
+				e->lastrun = TargetTime;
 				job_add(e, u);
 			}
 		}
 	}
+
+	last_time = TargetTime;
+	lasttm = *tm;
 }
 
 
@@ -216,7 +309,9 @@ cron_sync() {
 
 
 static void
-cron_sleep() {
+cron_sleep(db)
+	cron_db	*db;
+{
 	int	seconds_to_wait = 0;
 
 	/*
@@ -231,6 +326,7 @@ cron_sleep() {
 		 */
 
 		if (seconds_to_wait < -600 || seconds_to_wait > 600) {
+			cron_clean(db);
 			cron_sync();
 			continue;
 		}
@@ -255,6 +351,26 @@ cron_sleep() {
 }
 
 
+/* if the time was changed abruptly, clear the flags related
+ * to the daylight time switch handling to avoid strange effects
+ */
+
+static void
+cron_clean(db)
+	cron_db	*db;
+{
+	user		*u;
+	entry		*e;
+
+	last_time = 0;
+
+	for (u = db->head;  u != NULL;  u = u->next) {
+		for (e = u->crontab;  e != NULL;  e = e->next) {
+			e->flags &= ~(RUN_AT|NOT_UNTIL);
+		}
+	}
+}
+
 #ifdef USE_SIGCHLD
 static void
 sigchld_handler(x) {
@@ -299,8 +415,14 @@ parse_args(argc, argv)
 {
 	int	argch;
 
-	while ((argch = getopt(argc, argv, "x:")) != -1) {
+	while ((argch = getopt(argc, argv, "osx:")) != -1) {
 		switch (argch) {
+		case 'o':
+			dst_enabled = 0;
+			break;
+		case 's':
+			dst_enabled = 1;
+			break;
 		case 'x':
 			if (!set_debug_flags(optarg))
 				usage();
@@ -310,3 +432,4 @@ parse_args(argc, argv)
 		}
 	}
 }
+
diff --git a/usr.sbin/cron/cron/cron.h b/usr.sbin/cron/cron/cron.h
index 9d7b8d3..33bdf92 100644
--- a/usr.sbin/cron/cron/cron.h
+++ b/usr.sbin/cron/cron/cron.h
@@ -172,6 +172,9 @@ typedef	struct _entry {
 #define	DOM_STAR	0x01
 #define	DOW_STAR	0x02
 #define	WHEN_REBOOT	0x04
+#define	RUN_AT	0x08
+#define	NOT_UNTIL	0x10
+	time_t	lastrun;
 } entry;
 
 			/* the crontab database will be a list of the