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
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
|
/* SPDX-License-Identifier: LGPL-2.1-or-later */
/* systemd service to wait until kernel realtime clock is synchronized */
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/inotify.h>
#include <sys/timerfd.h>
#include <sys/timex.h>
#include <unistd.h>
#include "sd-event.h"
#include "fd-util.h"
#include "inotify-util.h"
#include "main-func.h"
#include "signal-util.h"
#include "time-util.h"
typedef struct ClockState {
int timerfd_fd; /* non-negative is descriptor from timerfd_create */
int adjtime_state; /* return value from last adjtimex(2) call */
sd_event_source *timerfd_event_source; /* non-null is the active io event source */
int inotify_fd;
sd_event_source *inotify_event_source;
int run_systemd_wd;
int run_systemd_timesync_wd;
bool has_watchfile;
} ClockState;
static void clock_state_release_timerfd(ClockState *sp) {
sp->timerfd_event_source = sd_event_source_unref(sp->timerfd_event_source);
sp->timerfd_fd = safe_close(sp->timerfd_fd);
}
static void clock_state_release(ClockState *sp) {
clock_state_release_timerfd(sp);
sp->inotify_event_source = sd_event_source_unref(sp->inotify_event_source);
sp->inotify_fd = safe_close(sp->inotify_fd);
}
static int clock_state_update(ClockState *sp, sd_event *event);
static int update_notify_run_systemd_timesync(ClockState *sp) {
sp->run_systemd_timesync_wd = inotify_add_watch(sp->inotify_fd, "/run/systemd/timesync", IN_CREATE|IN_DELETE_SELF);
return sp->run_systemd_timesync_wd;
}
static int timerfd_handler(sd_event_source *s,
int fd,
uint32_t revents,
void *userdata) {
ClockState *sp = userdata;
return clock_state_update(sp, sd_event_source_get_event(s));
}
static void process_inotify_event(sd_event *event, ClockState *sp, struct inotify_event *e) {
if (e->wd == sp->run_systemd_wd) {
/* Only thing we care about is seeing if we can start watching /run/systemd/timesync. */
if (sp->run_systemd_timesync_wd < 0)
update_notify_run_systemd_timesync(sp);
} else if (e->wd == sp->run_systemd_timesync_wd) {
if (e->mask & IN_DELETE_SELF) {
/* Somebody removed /run/systemd/timesync. */
(void) inotify_rm_watch(sp->inotify_fd, sp->run_systemd_timesync_wd);
sp->run_systemd_timesync_wd = -1;
} else
/* Somebody might have created /run/systemd/timesync/synchronized. */
clock_state_update(sp, event);
}
}
static int inotify_handler(sd_event_source *s,
int fd,
uint32_t revents,
void *userdata) {
sd_event *event = sd_event_source_get_event(s);
ClockState *sp = userdata;
union inotify_event_buffer buffer;
ssize_t l;
l = read(fd, &buffer, sizeof(buffer));
if (l < 0) {
if (ERRNO_IS_TRANSIENT(errno))
return 0;
return log_warning_errno(errno, "Lost access to inotify: %m");
}
FOREACH_INOTIFY_EVENT_WARN(e, buffer, l)
process_inotify_event(event, sp, e);
return 0;
}
static int clock_state_update(
ClockState *sp,
sd_event *event) {
struct timex tx = {};
usec_t t;
int r;
clock_state_release_timerfd(sp);
/* The kernel supports cancelling timers whenever its realtime clock is "set" (which can happen in a variety of
* ways, generally adjustments of at least 500 ms). The way this module works is we set up a timerfd that will
* wake when the clock is set, and when that happens we read the clock synchronization state from the return
* value of adjtimex(2), which supports the NTP time adjustment protocol.
*
* The kernel determines whether the clock is synchronized using driver-specific tests, based on time
* information passed by an application, generally through adjtimex(2). If the application asserts the clock is
* synchronized, but does not also do something that "sets the clock", the timer will not be cancelled and
* synchronization will not be detected.
*
* Similarly, this service will never complete if the application sets the time without also providing
* information that adjtimex(2) can use to determine that the clock is synchronized. This generally doesn't
* happen, but can if the system has a hardware clock that is accurate enough that the adjustment is too small
* to be a "set".
*
* Both these failure-to-detect situations are covered by having the presence/creation of
* /run/systemd/timesync/synchronized, which is considered sufficient to indicate a synchronized clock even if
* the kernel has not been updated.
*
* For timesyncd the initial setting of the time uses settimeofday(2), which sets the clock but does not mark
* it synchronized. When an NTP source is selected it sets the clock again with clock_adjtime(2) which marks it
* synchronized and also touches /run/systemd/timesync/synchronized which covers the case when the clock wasn't
* "set". */
r = time_change_fd();
if (r < 0) {
log_error_errno(r, "Failed to create timerfd: %m");
goto finish;
}
sp->timerfd_fd = r;
r = adjtimex(&tx);
if (r < 0) {
log_error_errno(errno, "Failed to read adjtimex state: %m");
goto finish;
}
sp->adjtime_state = r;
if (tx.status & STA_NANO)
tx.time.tv_usec /= 1000;
t = timeval_load(&tx.time);
log_info("adjtime state %i status %x time %s", sp->adjtime_state, (unsigned) tx.status,
FORMAT_TIMESTAMP_STYLE(t, TIMESTAMP_US_UTC) ?: "unrepresentable");
sp->has_watchfile = access("/run/systemd/timesync/synchronized", F_OK) >= 0;
if (sp->has_watchfile)
/* Presence of watch file overrides adjtime_state */
r = 0;
else if (sp->adjtime_state == TIME_ERROR) {
/* Not synchronized. Do a one-shot wait on the descriptor and inform the caller we need to keep
* running. */
r = sd_event_add_io(event, &sp->timerfd_event_source, sp->timerfd_fd,
EPOLLIN, timerfd_handler, sp);
if (r < 0) {
log_error_errno(r, "Failed to create time change monitor source: %m");
goto finish;
}
r = 1;
} else
/* Synchronized; we can exit. */
r = 0;
finish:
if (r <= 0)
(void) sd_event_exit(event, r);
return r;
}
static int run(int argc, char * argv[]) {
_cleanup_(sd_event_unrefp) sd_event *event = NULL;
_cleanup_(clock_state_release) ClockState state = {
.timerfd_fd = -1,
.inotify_fd = -1,
.run_systemd_wd = -1,
.run_systemd_timesync_wd = -1,
};
int r;
assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, -1) >= 0);
r = sd_event_default(&event);
if (r < 0)
return log_error_errno(r, "Failed to allocate event loop: %m");
r = sd_event_add_signal(event, NULL, SIGTERM, NULL, NULL);
if (r < 0)
return log_error_errno(r, "Failed to create sigterm event source: %m");
r = sd_event_add_signal(event, NULL, SIGINT, NULL, NULL);
if (r < 0)
return log_error_errno(r, "Failed to create sigint event source: %m");
r = sd_event_set_watchdog(event, true);
if (r < 0)
return log_error_errno(r, "Failed to create watchdog event source: %m");
r = inotify_init1(IN_NONBLOCK|IN_CLOEXEC);
if (r < 0)
return log_error_errno(errno, "Failed to create inotify descriptor: %m");
state.inotify_fd = r;
r = sd_event_add_io(event, &state.inotify_event_source, state.inotify_fd,
EPOLLIN, inotify_handler, &state);
if (r < 0)
return log_error_errno(r, "Failed to create notify event source: %m");
r = inotify_add_watch_and_warn(state.inotify_fd, "/run/systemd/", IN_CREATE);
if (r < 0)
return r;
state.run_systemd_wd = r;
(void) update_notify_run_systemd_timesync(&state);
r = clock_state_update(&state, event);
if (r > 0) {
r = sd_event_loop(event);
if (r < 0)
log_error_errno(r, "Failed in event loop: %m");
}
if (state.has_watchfile)
log_debug("Exit enabled by: /run/systemd/timesync/synchronized");
if (state.adjtime_state == TIME_ERROR)
log_info("Exit without adjtimex synchronized.");
return r;
}
DEFINE_MAIN_FUNCTION(run);
|
