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/* SPDX-License-Identifier: LGPL-2.1+ */
/***
Copyright 2010-2012 Lennart Poettering
***/
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdbool.h>
#include <time.h>
#include <linux/rtc.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include "clock-util.h"
#include "fd-util.h"
#include "macro.h"
#include "string-util.h"
#include "util.h"
int clock_get_hwclock(struct tm *tm) {
_cleanup_close_ int fd = -1;
assert(tm);
fd = open("/dev/rtc", O_RDONLY|O_CLOEXEC);
if (fd < 0)
return -errno;
/* This leaves the timezone fields of struct tm
* uninitialized! */
if (ioctl(fd, RTC_RD_TIME, tm) < 0)
return -errno;
/* We don't know daylight saving, so we reset this in order not
* to confuse mktime(). */
tm->tm_isdst = -1;
return 0;
}
int clock_set_hwclock(const struct tm *tm) {
_cleanup_close_ int fd = -1;
assert(tm);
fd = open("/dev/rtc", O_RDONLY|O_CLOEXEC);
if (fd < 0)
return -errno;
if (ioctl(fd, RTC_SET_TIME, tm) < 0)
return -errno;
return 0;
}
int clock_is_localtime(const char* adjtime_path) {
_cleanup_fclose_ FILE *f;
if (!adjtime_path)
adjtime_path = "/etc/adjtime";
/*
* The third line of adjtime is "UTC" or "LOCAL" or nothing.
* # /etc/adjtime
* 0.0 0 0
* 0
* UTC
*/
f = fopen(adjtime_path, "re");
if (f) {
char line[LINE_MAX];
bool b;
b = fgets(line, sizeof(line), f) &&
fgets(line, sizeof(line), f) &&
fgets(line, sizeof(line), f);
if (!b)
/* less than three lines -> default to UTC */
return 0;
truncate_nl(line);
return streq(line, "LOCAL");
} else if (errno != ENOENT)
return -errno;
/* adjtime not present -> default to UTC */
return 0;
}
int clock_set_timezone(int *min) {
const struct timeval *tv_null = NULL;
struct timespec ts;
struct tm *tm;
int minutesdelta;
struct timezone tz;
assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);
assert_se(tm = localtime(&ts.tv_sec));
minutesdelta = tm->tm_gmtoff / 60;
tz.tz_minuteswest = -minutesdelta;
tz.tz_dsttime = 0; /* DST_NONE */
/*
* If the RTC does not run in UTC but in local time, the very first
* call to settimeofday() will set the kernel's timezone and will warp the
* system clock, so that it runs in UTC instead of the local time we
* have read from the RTC.
*/
if (settimeofday(tv_null, &tz) < 0)
return negative_errno();
if (min)
*min = minutesdelta;
return 0;
}
int clock_reset_timewarp(void) {
const struct timeval *tv_null = NULL;
struct timezone tz;
tz.tz_minuteswest = 0;
tz.tz_dsttime = 0; /* DST_NONE */
/*
* The very first call to settimeofday() does time warp magic. Do a
* dummy call here, so the time warping is sealed and all later calls
* behave as expected.
*/
if (settimeofday(tv_null, &tz) < 0)
return -errno;
return 0;
}
#define TIME_EPOCH_USEC ((usec_t) TIME_EPOCH * USEC_PER_SEC)
int clock_apply_epoch(void) {
struct timespec ts;
if (now(CLOCK_REALTIME) >= TIME_EPOCH_USEC)
return 0;
if (clock_settime(CLOCK_REALTIME, timespec_store(&ts, TIME_EPOCH_USEC)) < 0)
return -errno;
return 1;
}
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