149 lines
3.7 KiB
C
149 lines
3.7 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <time.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 "clock-util.h"
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#include "fd-util.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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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(const char* adjtime_path) {
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_cleanup_fclose_ FILE *f;
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if (!adjtime_path)
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adjtime_path = "/etc/adjtime";
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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(adjtime_path, "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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/* less than three lines -> default to UTC */
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return 0;
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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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/* adjtime not present -> default to UTC */
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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(localtime_r(&ts.tv_sec, &tm));
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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 negative_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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#define TIME_EPOCH_USEC ((usec_t) TIME_EPOCH * USEC_PER_SEC)
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int clock_apply_epoch(void) {
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struct timespec ts;
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if (now(CLOCK_REALTIME) >= TIME_EPOCH_USEC)
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return 0;
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if (clock_settime(CLOCK_REALTIME, timespec_store(&ts, TIME_EPOCH_USEC)) < 0)
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return -errno;
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return 1;
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}
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