1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#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 "alloc-util.h"
#include "clock-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "macro.h"
#include "string-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;
return RET_NERRNO(ioctl(fd, RTC_SET_TIME, tm));
}
int clock_is_localtime(const char* adjtime_path) {
_cleanup_fclose_ FILE *f = NULL;
int r;
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) {
_cleanup_free_ char *line = NULL;
unsigned i;
for (i = 0; i < 2; i++) { /* skip the first two lines */
r = read_line(f, LONG_LINE_MAX, NULL);
if (r < 0)
return r;
if (r == 0)
return false; /* less than three lines → default to UTC */
}
r = read_line(f, LONG_LINE_MAX, &line);
if (r < 0)
return r;
if (r == 0)
return false; /* less than three lines → default to UTC */
return streq(line, "LOCAL");
} else if (errno != ENOENT)
return -errno;
/* adjtime not present → default to UTC */
return false;
}
int clock_set_timezone(int *ret_minutesdelta) {
struct timespec ts;
struct tm tm;
int minutesdelta;
struct timezone tz;
assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);
assert_se(localtime_r(&ts.tv_sec, &tm));
minutesdelta = tm.tm_gmtoff / 60;
tz = (struct timezone) {
.tz_minuteswest = -minutesdelta,
.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(NULL, &tz) < 0)
return -errno;
if (ret_minutesdelta)
*ret_minutesdelta = minutesdelta;
return 0;
}
int clock_reset_timewarp(void) {
static const struct timezone tz = {
.tz_minuteswest = 0,
.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. */
return RET_NERRNO(settimeofday(NULL, &tz));
}
#define EPOCH_FILE "/usr/lib/clock-epoch"
int clock_apply_epoch(ClockChangeDirection *ret_attempted_change) {
usec_t epoch_usec, now_usec;
struct stat st;
/* NB: we update *ret_attempted_change in *all* cases, both
* on success and failure, to indicate what we intended to do! */
assert(ret_attempted_change);
if (stat(EPOCH_FILE, &st) < 0) {
if (errno != ENOENT)
log_warning_errno(errno, "Cannot stat " EPOCH_FILE ": %m");
epoch_usec = (usec_t) TIME_EPOCH * USEC_PER_SEC;
} else
epoch_usec = timespec_load(&st.st_mtim);
now_usec = now(CLOCK_REALTIME);
if (now_usec < epoch_usec)
*ret_attempted_change = CLOCK_CHANGE_FORWARD;
else if (now_usec > usec_add(epoch_usec, CLOCK_VALID_RANGE_USEC_MAX))
*ret_attempted_change = CLOCK_CHANGE_BACKWARD;
else {
*ret_attempted_change = CLOCK_CHANGE_NOOP;
return 0;
}
if (clock_settime(CLOCK_REALTIME, TIMESPEC_STORE(epoch_usec)) < 0)
return -errno;
return 1;
}
|
