144 lines
3.8 KiB
C
144 lines
3.8 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 <errno.h>
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#include <fcntl.h>
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#include <linux/rtc.h>
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#include <stdio.h>
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#include <sys/ioctl.h>
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#include <sys/time.h>
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#include "macro.h"
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#include "string-util.h"
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#include "util.h"
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#include "clock-util.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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