PR: bin/5572

    Prevent cron from going crazy if the time steps.  For example, if you
    have a system with hundreds of users and lots of different crontabs
    and your time steps back an hour, the old cron would then attempt to
    run an hours worth of cron jobs in a few seconds.

1 files changed, 28 insertions, 16 deletions

diff --git a/usr.sbin/cron/cron/cron.c b/usr.sbin/cron/cron/cron.c
index 2389c9b..ff90831 100644
--- a/usr.sbin/cron/cron/cron.c
+++ b/usr.sbin/cron/cron/cron.c
@@ -17,7 +17,7 @@
 
 #if !defined(lint) && !defined(LINT)
 static const char rcsid[] =
-	"$Id: cron.c,v 1.6 1997/09/15 06:39:04 charnier Exp $";
+	"$Id: cron.c,v 1.7 1998/07/06 20:28:04 bde Exp $";
 #endif
 
 #define	MAIN_PROGRAM
@@ -227,28 +227,40 @@ cron_sync() {
 
 static void
 cron_sleep() {
-	register int	seconds_to_wait;
+	int	seconds_to_wait = 0;
 
-	do {
+	/*
+	 * Loop until we reach the top of the next minute, sleep when possible.
+	 */
+
+	for (;;) {
 		seconds_to_wait = (int) (TargetTime - time((time_t*)0));
+
+		/*
+		 * If the seconds_to_wait value is insane, jump the cron
+		 */
+
+		if (seconds_to_wait < -600 || seconds_to_wait > 600) {
+			cron_sync();
+			continue;
+		}
+
 		Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 			getpid(), (long)TargetTime, seconds_to_wait))
 
-		/* if we intend to sleep, this means that it's finally
-		 * time to empty the job queue (execute it).
-		 *
-		 * if we run any jobs, we'll probably screw up our timing,
-		 * so go recompute.
-		 *
-		 * note that we depend here on the left-to-right nature
-		 * of &&, and the short-circuiting.
+		/*
+		 * If we've run out of wait time or there are no jobs left
+		 * to run, break
 		 */
-	} while (seconds_to_wait > 0 && job_runqueue());
 
-	while (seconds_to_wait > 0) {
-		Debug(DSCH, ("[%d] sleeping for %d seconds\n",
-			getpid(), seconds_to_wait))
-		seconds_to_wait = (int) sleep((unsigned int) seconds_to_wait);
+		if (seconds_to_wait <= 0)
+			break;
+		if (job_runqueue() == 0) {
+			Debug(DSCH, ("[%d] sleeping for %d seconds\n",
+				getpid(), seconds_to_wait))
+
+			sleep(seconds_to_wait);
+		}
 	}
 }