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 | 117 ++++++++++++++++++++++++++++++++++++++++---
4 files changed, 142 insertions(+), 9 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 cb3f95c..efb659d 100644
--- a/doc/chrony.conf.adoc
+++ b/doc/chrony.conf.adoc
@@ -674,9 +674,10 @@ 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
@@ -1263,6 +1264,18 @@ $ 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 c8a42cb..bab1663 100644
--- a/leapdb.c
+++ b/leapdb.c
@@ -3,6 +3,7 @@
**********************************************************************
* Copyright (C) Miroslav Lichvar 2009-2018, 2020, 2022
+ * Copyright (C) Patrick Oppenlander 2023
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
@@ -33,8 +34,16 @@
/* ================================================== */
-/* Name of a system timezone containing leap seconds occuring at midnight */
-static char *leap_tzname;
+/* Source of leap second data */
+enum {
+ SRC_NONE,
+ SRC_TZ,
+ SRC_LEAP_SEC_LIST,
+} leap_src;
+
+/* Offset between leap-seconds.list timestamp epoch and Unix epoch.
+ leap-seconds.list epoch is 1 Jan 1900, 00:00:00 */
+static const long long LEAP_SEC_LIST_OFFSET = 2208988800;
/* ================================================== */
@@ -59,7 +68,7 @@ get_tz_leap(time_t when, int *tai_offset)
return tz_leap;
strcpy(tz_orig, tz_env);
}
- setenv("TZ", leap_tzname, 1);
+ setenv("TZ", CNF_GetLeapSecTimezone(), 1);
tzset();
/* Get the TAI-UTC offset, which started at the epoch at 10 seconds */
@@ -93,6 +102,78 @@ get_tz_leap(time_t when, int *tai_offset)
/* ================================================== */
+static NTP_Leap
+get_leap_sec_list_leap(time_t when, int *tai_offset)
+{
+ FILE *f;
+ char *line = NULL;
+ size_t linelen = 0;
+ NTP_Leap lsl_leap = LEAP_Normal;
+ int prev_lsl_tai_offset = 10;
+ long long lsl_updated = 0, lsl_expiry = 0;
+
+ if (!(f = fopen(CNF_GetLeapSecList(), "r"))) {
+ LOG(LOGS_ERR, "Failed to open leap seconds list %s", CNF_GetLeapSecList());
+ goto out;
+ }
+
+ /* 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 */
+ when += LEAP_SEC_LIST_OFFSET;
+
+ while (getline(&line, &linelen, f) > 0) {
+ long long lsl_when;
+ int lsl_tai_offset;
+
+ if (*line == '#') {
+ /* Update time line starts with #$ */
+ if (line[1] == '$' && sscanf(line + 2, "%lld", &lsl_updated) != 1)
+ goto error;
+ /* Expiration time line starts with #@ */
+ if (line[1] == '@' && sscanf(line + 2, "%lld", &lsl_expiry) != 1)
+ goto error;
+ /* Comment or a special comment we don't care about */
+ continue;
+ }
+
+ /* Leap entry */
+ if (sscanf(line, "%lld %d", &lsl_when, &lsl_tai_offset) != 2)
+ goto error;
+
+ if (when == lsl_when) {
+ if (lsl_tai_offset > prev_lsl_tai_offset)
+ lsl_leap = LEAP_InsertSecond;
+ else if (lsl_tai_offset < prev_lsl_tai_offset)
+ lsl_leap = LEAP_DeleteSecond;
+ /* When is rounded to the end of the day, so offset hasn't changed yet!
*/
+ *tai_offset = prev_lsl_tai_offset;
+ } else if (when > lsl_when)
+ *tai_offset = lsl_tai_offset;
+
+ prev_lsl_tai_offset = lsl_tai_offset;
+ }
+
+ /* Make sure the file looks sensible */
+ if (!feof(f) || !lsl_updated || !lsl_expiry)
+ goto error;
+
+ if (when >= lsl_expiry)
+ LOG(LOGS_WARN, "Leap second list %s needs update", CNF_GetLeapSecList());
+
+ goto out;
+
+error:
+ LOG(LOGS_ERR, "Failed to parse leap seconds list %s", CNF_GetLeapSecList());
+out:
+ if (f)
+ fclose(f);
+ return lsl_leap;
+}
+
+/* ================================================== */
+
static int
check_leap_source(NTP_Leap (*src)(time_t when, int *tai_offset))
{
@@ -111,14 +192,30 @@ check_leap_source(NTP_Leap (*src)(time_t when, int
*tai_offset))
void
LDB_Initialise(void)
{
- leap_tzname = CNF_GetLeapSecTimezone();
+ const char *leap_tzname = CNF_GetLeapSecTimezone();
if (leap_tzname && !check_leap_source(get_tz_leap)) {
LOG(LOGS_WARN, "Timezone %s failed leap second check, ignoring",
leap_tzname);
leap_tzname = NULL;
}
- if (leap_tzname)
+ const char *leap_sec_list = CNF_GetLeapSecList();
+ if (leap_sec_list && !check_leap_source(get_leap_sec_list_leap)) {
+ LOG(LOGS_WARN, "Leap second list %s failed check, ignoring",
leap_sec_list);
+ leap_sec_list = NULL;
+ }
+
+ if (leap_sec_list && leap_tzname) {
+ LOG(LOGS_WARN, "Multiple leap second sources, ignoring leapsectz");
+ leap_tzname = NULL;
+ }
+
+ if (leap_sec_list) {
+ LOG(LOGS_INFO, "Using leap second list %s", leap_sec_list);
+ leap_src = SRC_LEAP_SEC_LIST;
+ } else if (leap_tzname) {
LOG(LOGS_INFO, "Using %s timezone to obtain leap second data",
leap_tzname);
+ leap_src = SRC_TZ;
+ }
}
/* ================================================== */
@@ -139,8 +236,16 @@ LDB_GetLeap(time_t when, int *tai_offset)
ldb_leap = LEAP_Normal;
ldb_tai_offset = 0;
- if (leap_tzname)
+ switch (leap_src) {
+ case SRC_NONE:
+ break;
+ case SRC_TZ:
ldb_leap = get_tz_leap(when, &ldb_tai_offset);
+ break;
+ case SRC_LEAP_SEC_LIST:
+ ldb_leap = get_leap_sec_list_leap(when, &ldb_tai_offset);
+ break;
+ }
out:
*tai_offset = ldb_tai_offset;
--
2.43.0
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