c264aeab4b
We can not reliably manage any notion of local time. Every daylight saving time change or time zone change by traveling will make the time jump, and the local time might jump backwards which creates unsolvable problems with file timestamps. We will no longer tell the kernel our local time zone and leave everything set to UTC. This will effectively turn FAT timestamps into UTC timestamps. If and only if the machine is configured to read the RTC in local time mode, the kernel's time zone will be configured, but systemd-timesysnc will disable the kernel's system time to RTC syncing. In this mode, the RTC will not be managed, and external tools like Windows bootups are expected to manage the RTC's time. https://bugs.freedesktop.org/show_bug.cgi?id=81538
156 lines
4.1 KiB
C
156 lines
4.1 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2010-2012 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd 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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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <assert.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <stdarg.h>
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#include <ctype.h>
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#include <sys/prctl.h>
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#include <sys/time.h>
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#include <linux/rtc.h>
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#include "macro.h"
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#include "util.h"
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#include "log.h"
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#include "strv.h"
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#include "clock-util.h"
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#include "fileio.h"
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int clock_get_hwclock(struct tm *tm) {
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_cleanup_close_ int fd = -1;
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assert(tm);
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fd = open("/dev/rtc", O_RDONLY|O_CLOEXEC);
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if (fd < 0)
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return -errno;
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/* This leaves the timezone fields of struct tm
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* uninitialized! */
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if (ioctl(fd, RTC_RD_TIME, tm) < 0)
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return -errno;
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/* We don't know daylight saving, so we reset this in order not
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* to confuse mktime(). */
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tm->tm_isdst = -1;
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return 0;
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}
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int clock_set_hwclock(const struct tm *tm) {
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_cleanup_close_ int fd = -1;
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assert(tm);
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fd = open("/dev/rtc", O_RDONLY|O_CLOEXEC);
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if (fd < 0)
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return -errno;
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if (ioctl(fd, RTC_SET_TIME, tm) < 0)
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return -errno;
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return 0;
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}
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int clock_is_localtime(void) {
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_cleanup_fclose_ FILE *f;
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/*
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* The third line of adjtime is "UTC" or "LOCAL" or nothing.
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* # /etc/adjtime
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* 0.0 0 0
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* 0
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* UTC
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*/
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f = fopen("/etc/adjtime", "re");
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if (f) {
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char line[LINE_MAX];
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bool b;
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b = fgets(line, sizeof(line), f) &&
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fgets(line, sizeof(line), f) &&
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fgets(line, sizeof(line), f);
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if (!b)
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return -EIO;
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truncate_nl(line);
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return streq(line, "LOCAL");
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} else if (errno != ENOENT)
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return -errno;
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return 0;
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}
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int clock_set_timezone(int *min) {
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const struct timeval *tv_null = NULL;
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struct timespec ts;
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struct tm *tm;
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int minutesdelta;
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struct timezone tz;
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assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);
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assert_se(tm = localtime(&ts.tv_sec));
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minutesdelta = tm->tm_gmtoff / 60;
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tz.tz_minuteswest = -minutesdelta;
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tz.tz_dsttime = 0; /* DST_NONE*/
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/*
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* If the RTC does not run in UTC but in local time, the very first
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* call to settimeofday() will set the kernel's timezone and will warp the
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* system clock, so that it runs in UTC instead of the local time we
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* have read from the RTC.
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*/
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if (settimeofday(tv_null, &tz) < 0)
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return -errno;
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if (min)
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*min = minutesdelta;
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return 0;
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}
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int clock_reset_timewarp(void) {
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const struct timeval *tv_null = NULL;
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struct timezone tz;
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tz.tz_minuteswest = 0;
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tz.tz_dsttime = 0; /* DST_NONE*/
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/*
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* The very first call to settimeofday() does time warp magic. Do a
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* dummy call here, so the time warping is sealed and all later calls
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* behave as expected.
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*/
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if (settimeofday(tv_null, &tz) < 0)
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return -errno;
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return 0;
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}
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