ntpd: explain why scripts can be run in quick succession

[oweals/busybox.git] / networking / ntpd.c

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 95dfdb1197e4b699fc6bde9bc23e7b9269441ab3..04df3fa7fa060d91e8b35458b811a3287fff34ee 100644 (file)
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -735,6 +735,13 @@ send_query_to_peer(peer_t *p)
 }
 
 
+/* Note that there is no provision to prevent several run_scripts
+ * to be done in quick succession. In fact, it happens rather often
+ * if initial syncronization results in a step.
+ * You will see "step" and then "stratum" script runs, sometimes
+ * as close as only 0.002 seconds apart.
+ * Script should be ready to deal with this.
+ */
 static void run_script(const char *action, double offset)
 {
        char *argv[3];
@@ -1185,8 +1192,8 @@ update_local_clock(peer_t *p)
        abs_offset = fabs(offset);
 
 #if 0
-       /* If needed, -S script can detect this by looking at $offset
-        * env var and kill parent */
+       /* If needed, -S script can do it by looking at $offset
+        * env var and killing parent */
        /* If the offset is too large, give up and go home */
        if (abs_offset > PANIC_THRESHOLD) {
                bb_error_msg_and_die("offset %f far too big, exiting", offset);
@@ -2007,7 +2014,7 @@ int ntpd_main(int argc UNUSED_PARAM, char **argv)
                nfds = poll(pfd, i, timeout * 1000);
                gettime1900d(); /* sets G.cur_time */
                if (nfds <= 0) {
-                       if (G.cur_time - G.last_script_run > 11*60) {
+                       if (G.script_name && G.cur_time - G.last_script_run > 11*60) {
                                /* Useful for updating battery-backed RTC and such */
                                run_script("periodic", G.last_update_offset);
                                gettime1900d(); /* sets G.cur_time */