From: Patrick Oppenlander <patrick.oppenlan...@gmail.com>
The existing implementation of getting leap second information from a
timezone in get_tz_leap() relies on non-portable C library behaviour.
Specifically, mktime is not required to return '60' in the tm_sec field
when a leap second is inserted leading to "Timezone right/UTC failed
leap second check, ignoring" errors on musl based systems.
This patch adds support for getting leap second information from the
leap-seconds.list file included with tzdata and adds a new configuration
directive leapseclist to switch on the feature.
---
conf.c | 14 +++++
conf.h | 1 +
doc/chrony.conf.adoc | 19 +++++-
leapdb.c | 135 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 166 insertions(+), 3 deletions(-)
diff --git a/conf.c b/conf.c
index fa74459..06857a8 100644
--- a/conf.c
+++ b/conf.c
@@ -249,6 +249,9 @@ static REF_LeapMode leapsec_mode = REF_LeapModeSystem;
/* Name of a system timezone containing leap seconds occuring at midnight */
static char *leapsec_tz = NULL;
+/* File name of leap seconds list, usually
/usr/share/zoneinfo/leap-seconds.list */
+static char *leapsec_list = NULL;
+
/* Name of the user to which will be dropped root privileges. */
static char *user;
@@ -471,6 +474,7 @@ CNF_Finalise(void)
Free(hwclock_file);
Free(keys_file);
Free(leapsec_tz);
+ Free(leapsec_list);
Free(logdir);
Free(bind_ntp_iface);
Free(bind_acq_iface);
@@ -620,6 +624,8 @@ CNF_ParseLine(const char *filename, int number, char *line)
parse_leapsecmode(p);
} else if (!strcasecmp(command, "leapsectz")) {
parse_string(p, &leapsec_tz);
+ } else if (!strcasecmp(command, "leapseclist")) {
+ parse_string(p, &leapsec_list);
} else if (!strcasecmp(command, "local")) {
parse_local(p);
} else if (!strcasecmp(command, "lock_all")) {
@@ -2386,6 +2392,14 @@ CNF_GetLeapSecTimezone(void)
/* ================================================== */
+char *
+CNF_GetLeapSecList(void)
+{
+ return leapsec_list;
+}
+
+/* ================================================== */
+
int
CNF_GetSchedPriority(void)
{
diff --git a/conf.h b/conf.h
index 58ebdeb..4c0a787 100644
--- a/conf.h
+++ b/conf.h
@@ -91,6 +91,7 @@ extern char *CNF_GetNtpSigndSocket(void);
extern char *CNF_GetPidFile(void);
extern REF_LeapMode CNF_GetLeapSecMode(void);
extern char *CNF_GetLeapSecTimezone(void);
+extern char *CNF_GetLeapSecList(void);
/* Value returned in ppm, as read from file */
extern double CNF_GetMaxUpdateSkew(void);
diff --git a/doc/chrony.conf.adoc b/doc/chrony.conf.adoc
index abb8403..41646c4 100644
--- a/doc/chrony.conf.adoc
+++ b/doc/chrony.conf.adoc
@@ -672,9 +672,10 @@ trusted and required source.
*tai*:::
This option indicates that the reference clock keeps time in TAI instead of UTC
and that *chronyd* should correct its offset by the current TAI-UTC offset. The
-<<leapsectz,*leapsectz*>> directive must be used with this option and the
-database must be kept up to date in order for this correction to work as
-expected. This option does not make sense with PPS refclocks.
+<<leapsectz,*leapsectz*>> or <<leapseclist,*leapseclist*>> directive must be
+used with this option and the database must be kept up to date in order for
+this correction to work as expected. This option does not make sense with PPS
+refclocks.
*local*:::
This option specifies that the reference clock is an unsynchronised clock which
is more stable than the system clock (e.g. TCXO, OCXO, or atomic clock) and
@@ -1261,6 +1262,18 @@ $ TZ=right/UTC date -d 'Dec 31 2008 23:59:60'
Wed Dec 31 23:59:60 UTC 2008
----
+[[leapseclist]]*leapseclist* _file_::
+This directive specifies the path to a file containing a list of leap seconds.
+It is recommended to use the file _leap-seconds.list_ usually included with the
+system timezone database. The behaviour of this directive is otherwise
equivalent
+to <<leapsectz,*leapsectz*>>.
++
+An example of this directive is:
++
+----
+leapseclist /usr/share/zoneinfo/leap-seconds.list
+----
+
[[makestep]]*makestep* _threshold_ _limit_::
Normally *chronyd* will cause the system to gradually correct any time offset,
by slowing down or speeding up the clock as required. In certain situations,
diff --git a/leapdb.c b/leapdb.c
index 98bb2f5..c790c20 100644
--- a/leapdb.c
+++ b/leapdb.c
@@ -35,9 +35,24 @@
typedef NTP_Leap (*GetLeapFn)(time_t when, int *tai_offset);
+/* Offset between leap-seconds.list epoch timestamps and Unix epoch.
+ leap-seconds.list epoch is 1 Jan 1900, 00:00:00 */
+static const long long LEAP_SECONDS_LIST_OFFSET = 2208988800;
+
/* Current leap second data source */
GetLeapFn get_leap;
+/* Leap second database */
+struct leapdb {
+ long long updated;
+ long long expiry;
+ size_t len;
+ struct leap {
+ long long when;
+ int tai_offset;
+ } leap[];
+};
+
/* ================================================== */
static NTP_Leap
@@ -95,6 +110,110 @@ get_tz_leap(time_t when, int *tai_offset)
/* ================================================== */
+static struct leapdb *
+read_leap_seconds_list(const char *file)
+{
+ size_t ll = 0;
+ size_t len = 32; /* 28 entries to 1 Jan 2017 */
+ struct leapdb *db = calloc(1, sizeof *db + sizeof *db->leap * len);
+ FILE *f = fopen(file, "r");
+ char *l = NULL;
+
+ if (!db || !f)
+ goto error;
+
+ while (getline(&l, &ll, f) > 0) {
+ if (*l == '#') {
+ /* update time */
+ if (l[1] == '$' && sscanf(l + 2, "%lld", &db->updated) != 1)
+ goto error;
+ /* expiration time */
+ if (l[1] == '@' && sscanf(l + 2, "%lld", &db->expiry) != 1)
+ goto error;
+ /* comment or a special comment we don't care about */
+ continue;
+ }
+
+ if (db->len >= len) {
+ len += len / 2;
+ void *p = realloc(db, sizeof *db + sizeof *db->leap * len);
+ if (!p)
+ goto error;
+ db = p;
+ }
+
+ /* leap entry */
+ struct leap *lp = db->leap + db->len;
+ if (sscanf(l, "%lld %d", &lp->when, &lp->tai_offset) != 2)
+ goto error;
+ ++db->len;
+ }
+
+ /* make sure the database looks sensible */
+ if (!feof(f) || !db->updated || !db->expiry || !db->len)
+ goto error;
+
+ goto out;
+
+error:
+ free(db);
+ db = 0;
+out:
+ free(l);
+ if (f)
+ fclose(f);
+ return db;
+}
+
+/* ================================================== */
+
+static NTP_Leap
+get_db_leap(time_t when, int *tai_offset)
+{
+ NTP_Leap db_leap = LEAP_Normal;
+ struct leapdb *db = read_leap_seconds_list(CNF_GetLeapSecList());
+
+ if (!db) {
+ LOG(LOGS_ERR, "Failed to read leap second list %s", CNF_GetLeapSecList());
+ return db_leap;
+ }
+
+ /* leap second happens at midnight */
+ when = (when / (24 * 3600) + 1) * (24 * 3600);
+
+ /* leap-seconds.list timestamps are relative to 1 Jan 1900, 00:00:00 */
+ long long leap_when = when + LEAP_SECONDS_LIST_OFFSET;
+ db_leap = LEAP_Normal;
+
+ if (leap_when >= db->expiry)
+ LOG(LOGS_WARN, "Leap second list %s needs update", CNF_GetLeapSecList());
+
+ /* find leap entry */
+ struct leap *lp = db->leap;
+ for (int i = db->len - 1; i >= 0; --i) {
+ lp = db->leap + i;
+ if (leap_when >= lp->when)
+ break;
+ }
+
+ if (leap_when == lp->when) {
+ struct leap *lp_prev = lp > db->leap ? lp - 1 : db->leap;
+ if (lp->tai_offset > lp_prev->tai_offset) {
+ db_leap = LEAP_InsertSecond;
+ } else if (lp->tai_offset < lp_prev->tai_offset)
+ db_leap = LEAP_DeleteSecond;
+ /* tai offset hasn't changed yet! */
+ *tai_offset = lp_prev->tai_offset;
+ } else
+ *tai_offset = lp->tai_offset;
+
+ free(db);
+
+ return db_leap;
+}
+
+/* ================================================== */
+
static int
check_leap_source(GetLeapFn fn)
{
@@ -119,6 +238,22 @@ LDB_Initialise(void)
leap_tzname = NULL;
}
+ const char *leap_list = CNF_GetLeapSecList();
+ if (leap_list && !check_leap_source(get_db_leap)) {
+ LOG(LOGS_WARN, "Leap second list %s failed check, ignoring", leap_list);
+ leap_list = NULL;
+ }
+
+ if (leap_list && leap_tzname) {
+ LOG(LOGS_WARN, "Multiple leap second sources, ignoring leapsectz");
+ leap_tzname = NULL;
+ }
+
+ if (leap_list) {
+ LOG(LOGS_INFO, "Using leap second list %s", leap_list);
+ get_leap = get_db_leap;
+ }
+
if (leap_tzname) {
LOG(LOGS_INFO, "Using %s timezone to obtain leap second data",
leap_tzname);
get_leap = get_tz_leap;
--
2.43.0
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