02ae9a8607
We want to do the twice per day check regardless of the data source. Move the check up one level from get_tz_leap() into LDB_GetLeap().
146 lines
3.6 KiB
C
146 lines
3.6 KiB
C
/*
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chronyd/chronyc - Programs for keeping computer clocks accurate.
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**********************************************************************
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* Copyright (C) Miroslav Lichvar 2009-2018, 2020, 2022
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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**********************************************************************
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=======================================================================
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This module provides leap second information. */
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#include "config.h"
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#include "sysincl.h"
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#include "conf.h"
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#include "leapdb.h"
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#include "logging.h"
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/* ================================================== */
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/* Name of a system timezone containing leap seconds occuring at midnight */
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static char *leap_tzname;
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/* ================================================== */
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static NTP_Leap
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get_tz_leap(time_t when, int *tai_offset)
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{
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struct tm stm, *tm;
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time_t t;
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char *tz_env, tz_orig[128];
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NTP_Leap tz_leap = LEAP_Normal;
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tm = gmtime(&when);
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if (!tm)
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return tz_leap;
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stm = *tm;
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/* Temporarily switch to the timezone containing leap seconds */
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tz_env = getenv("TZ");
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if (tz_env) {
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if (strlen(tz_env) >= sizeof (tz_orig))
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return tz_leap;
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strcpy(tz_orig, tz_env);
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}
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setenv("TZ", leap_tzname, 1);
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tzset();
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/* Get the TAI-UTC offset, which started at the epoch at 10 seconds */
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t = mktime(&stm);
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if (t != -1)
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*tai_offset = t - when + 10;
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/* Set the time to 23:59:60 and see how it overflows in mktime() */
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stm.tm_sec = 60;
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stm.tm_min = 59;
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stm.tm_hour = 23;
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t = mktime(&stm);
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if (tz_env)
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setenv("TZ", tz_orig, 1);
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else
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unsetenv("TZ");
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tzset();
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if (t == -1)
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return tz_leap;
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if (stm.tm_sec == 60)
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tz_leap = LEAP_InsertSecond;
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else if (stm.tm_sec == 1)
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tz_leap = LEAP_DeleteSecond;
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return tz_leap;
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}
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/* ================================================== */
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void
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LDB_Initialise(void)
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{
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int tai_offset;
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leap_tzname = CNF_GetLeapSecTimezone();
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if (leap_tzname) {
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/* Check that the timezone has good data for Jun 30 2012 and Dec 31 2012 */
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if (get_tz_leap(1341014400, &tai_offset) == LEAP_InsertSecond && tai_offset == 34 &&
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get_tz_leap(1356912000, &tai_offset) == LEAP_Normal && tai_offset == 35) {
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LOG(LOGS_INFO, "Using %s timezone to obtain leap second data", leap_tzname);
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} else {
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LOG(LOGS_WARN, "Timezone %s failed leap second check, ignoring", leap_tzname);
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leap_tzname = NULL;
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}
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}
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}
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/* ================================================== */
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NTP_Leap
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LDB_GetLeap(time_t when, int *tai_offset)
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{
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static time_t last_ldb_leap_check;
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static NTP_Leap ldb_leap;
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static int ldb_tai_offset;
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/* Do this check at most twice a day */
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when = when / (12 * 3600) * (12 * 3600);
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if (last_ldb_leap_check == when)
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goto out;
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last_ldb_leap_check = when;
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ldb_leap = LEAP_Normal;
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ldb_tai_offset = 0;
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if (leap_tzname)
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ldb_leap = get_tz_leap(when, &ldb_tai_offset);
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out:
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*tai_offset = ldb_tai_offset;
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return ldb_leap;
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}
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/* ================================================== */
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void
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LDB_Finalise(void)
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{
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/* Nothing to do */
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}
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