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Commit | Line | Data |
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5c3376ef PB |
1 | /* |
2 | * systemd service to wait until kernel realtime clock is synchronized | |
3 | * | |
5c3376ef PB |
4 | * You should have received a copy of the GNU General Public License |
5 | * along with this program; if not, write to the Free Software | |
6 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 | |
7 | * USA | |
8 | */ | |
9 | ||
10 | #include <errno.h> | |
11 | #include <signal.h> | |
12 | #include <stdbool.h> | |
13 | #include <stdio.h> | |
14 | #include <stdlib.h> | |
15 | #include <string.h> | |
2dd79846 | 16 | #include <sys/inotify.h> |
5c3376ef PB |
17 | #include <sys/timerfd.h> |
18 | #include <sys/timex.h> | |
19 | #include <unistd.h> | |
20 | ||
21 | #include "sd-event.h" | |
22 | ||
23 | #include "fd-util.h" | |
2dd79846 | 24 | #include "fs-util.h" |
1d03c5c1 | 25 | #include "main-func.h" |
5c3376ef PB |
26 | #include "missing.h" |
27 | #include "signal-util.h" | |
28 | #include "time-util.h" | |
29 | ||
30 | typedef struct ClockState { | |
2dd79846 PB |
31 | int timerfd_fd; /* non-negative is descriptor from timerfd_create */ |
32 | int adjtime_state; /* return value from last adjtimex(2) call */ | |
33 | sd_event_source *timerfd_event_source; /* non-null is the active io event source */ | |
34 | int inotify_fd; | |
35 | sd_event_source *inotify_event_source; | |
36 | int run_systemd_wd; | |
37 | int run_systemd_timesync_wd; | |
38 | bool has_watchfile; | |
5c3376ef PB |
39 | } ClockState; |
40 | ||
2dd79846 PB |
41 | static void clock_state_release_timerfd(ClockState *sp) { |
42 | sp->timerfd_event_source = sd_event_source_unref(sp->timerfd_event_source); | |
43 | sp->timerfd_fd = safe_close(sp->timerfd_fd); | |
44 | } | |
45 | ||
5c3376ef | 46 | static void clock_state_release(ClockState *sp) { |
2dd79846 PB |
47 | clock_state_release_timerfd(sp); |
48 | sp->inotify_event_source = sd_event_source_unref(sp->inotify_event_source); | |
49 | sp->inotify_fd = safe_close(sp->inotify_fd); | |
5c3376ef PB |
50 | } |
51 | ||
0fad9daf | 52 | static int clock_state_update(ClockState *sp, sd_event *event); |
5c3376ef | 53 | |
2dd79846 PB |
54 | static int update_notify_run_systemd_timesync(ClockState *sp) { |
55 | sp->run_systemd_timesync_wd = inotify_add_watch(sp->inotify_fd, "/run/systemd/timesync", IN_CREATE|IN_DELETE_SELF); | |
56 | return sp->run_systemd_timesync_wd; | |
57 | } | |
58 | ||
59 | static int timerfd_handler(sd_event_source *s, | |
60 | int fd, | |
61 | uint32_t revents, | |
62 | void *userdata) { | |
5c3376ef PB |
63 | ClockState *sp = userdata; |
64 | ||
65 | return clock_state_update(sp, sd_event_source_get_event(s)); | |
66 | } | |
67 | ||
2dd79846 PB |
68 | static void process_inotify_event(sd_event *event, ClockState *sp, struct inotify_event *e) { |
69 | if (e->wd == sp->run_systemd_wd) { | |
70 | /* Only thing we care about is seeing if we can start watching /run/systemd/timesync. */ | |
71 | if (sp->run_systemd_timesync_wd < 0) | |
72 | update_notify_run_systemd_timesync(sp); | |
73 | } else if (e->wd == sp->run_systemd_timesync_wd) { | |
74 | if (e->mask & IN_DELETE_SELF) { | |
75 | /* Somebody removed /run/systemd/timesync. */ | |
76 | (void) inotify_rm_watch(sp->inotify_fd, sp->run_systemd_timesync_wd); | |
77 | sp->run_systemd_timesync_wd = -1; | |
78 | } else | |
79 | /* Somebody might have created /run/systemd/timesync/synchronized. */ | |
80 | clock_state_update(sp, event); | |
81 | } | |
82 | } | |
83 | ||
84 | static int inotify_handler(sd_event_source *s, | |
85 | int fd, | |
86 | uint32_t revents, | |
87 | void *userdata) { | |
88 | sd_event *event = sd_event_source_get_event(s); | |
89 | ClockState *sp = userdata; | |
90 | union inotify_event_buffer buffer; | |
91 | struct inotify_event *e; | |
92 | ssize_t l; | |
93 | ||
94 | l = read(fd, &buffer, sizeof(buffer)); | |
95 | if (l < 0) { | |
96 | if (IN_SET(errno, EAGAIN, EINTR)) | |
97 | return 0; | |
98 | ||
99 | return log_warning_errno(errno, "Lost access to inotify: %m"); | |
100 | } | |
101 | FOREACH_INOTIFY_EVENT(e, buffer, l) | |
102 | process_inotify_event(event, sp, e); | |
103 | ||
104 | return 0; | |
105 | } | |
106 | ||
4f811d27 LP |
107 | static int clock_state_update( |
108 | ClockState *sp, | |
109 | sd_event *event) { | |
110 | ||
5c3376ef | 111 | char buf[MAX((size_t)FORMAT_TIMESTAMP_MAX, STRLEN("unrepresentable"))]; |
4f811d27 | 112 | struct timex tx = {}; |
5c3376ef | 113 | const char * ts; |
4f811d27 LP |
114 | usec_t t; |
115 | int r; | |
5c3376ef | 116 | |
2dd79846 | 117 | clock_state_release_timerfd(sp); |
5c3376ef PB |
118 | |
119 | /* The kernel supports cancelling timers whenever its realtime clock is "set" (which can happen in a variety of | |
2dd79846 | 120 | * ways, generally adjustments of at least 500 ms). The way this module works is we set up a timerfd that will |
0fad9daf | 121 | * wake when the clock is set, and when that happens we read the clock synchronization state from the return |
5c3376ef PB |
122 | * value of adjtimex(2), which supports the NTP time adjustment protocol. |
123 | * | |
124 | * The kernel determines whether the clock is synchronized using driver-specific tests, based on time | |
2dd79846 PB |
125 | * information passed by an application, generally through adjtimex(2). If the application asserts the clock is |
126 | * synchronized, but does not also do something that "sets the clock", the timer will not be cancelled and | |
127 | * synchronization will not be detected. | |
5c3376ef PB |
128 | * |
129 | * Similarly, this service will never complete if the application sets the time without also providing | |
2dd79846 PB |
130 | * information that adjtimex(2) can use to determine that the clock is synchronized. This generally doesn't |
131 | * happen, but can if the system has a hardware clock that is accurate enough that the adjustment is too small | |
132 | * to be a "set". | |
133 | * | |
134 | * Both these failure-to-detect situations are covered by having the presence/creation of | |
135 | * /run/systemd/timesync/synchronized, which is considered sufficient to indicate a synchronized clock even if | |
136 | * the kernel has not been updated. | |
5c3376ef | 137 | * |
2dd79846 PB |
138 | * For timesyncd the initial setting of the time uses settimeofday(2), which sets the clock but does not mark |
139 | * it synchronized. When an NTP source is selected it sets the clock again with clock_adjtime(2) which marks it | |
140 | * synchronized and also touches /run/systemd/timesync/synchronized which covers the case when the clock wasn't | |
141 | * "set". */ | |
5c3376ef | 142 | |
4f811d27 | 143 | r = time_change_fd(); |
5c3376ef | 144 | if (r < 0) { |
4f811d27 | 145 | log_error_errno(r, "Failed to create timerfd: %m"); |
5c3376ef PB |
146 | goto finish; |
147 | } | |
4f811d27 | 148 | sp->timerfd_fd = r; |
5c3376ef PB |
149 | |
150 | r = adjtimex(&tx); | |
151 | if (r < 0) { | |
152 | log_error_errno(errno, "Failed to read adjtimex state: %m"); | |
153 | goto finish; | |
154 | } | |
155 | sp->adjtime_state = r; | |
156 | ||
157 | if (tx.status & STA_NANO) | |
158 | tx.time.tv_usec /= 1000; | |
159 | t = timeval_load(&tx.time); | |
160 | ts = format_timestamp_us_utc(buf, sizeof(buf), t); | |
161 | if (!ts) | |
162 | strcpy(buf, "unrepresentable"); | |
163 | log_info("adjtime state %d status %x time %s", sp->adjtime_state, tx.status, ts); | |
164 | ||
2dd79846 PB |
165 | sp->has_watchfile = access("/run/systemd/timesync/synchronized", F_OK) >= 0; |
166 | if (sp->has_watchfile) | |
167 | /* Presence of watch file overrides adjtime_state */ | |
168 | r = 0; | |
169 | else if (sp->adjtime_state == TIME_ERROR) { | |
170 | /* Not synchronized. Do a one-shot wait on the descriptor and inform the caller we need to keep | |
5c3376ef | 171 | * running. */ |
2dd79846 PB |
172 | r = sd_event_add_io(event, &sp->timerfd_event_source, sp->timerfd_fd, |
173 | EPOLLIN, timerfd_handler, sp); | |
5c3376ef PB |
174 | if (r < 0) { |
175 | log_error_errno(r, "Failed to create time change monitor source: %m"); | |
176 | goto finish; | |
177 | } | |
178 | r = 1; | |
2dd79846 | 179 | } else |
5c3376ef | 180 | /* Synchronized; we can exit. */ |
5c3376ef | 181 | r = 0; |
5c3376ef PB |
182 | |
183 | finish: | |
2dd79846 | 184 | if (r <= 0) |
5c3376ef PB |
185 | (void) sd_event_exit(event, r); |
186 | return r; | |
187 | } | |
188 | ||
1d03c5c1 | 189 | static int run(int argc, char * argv[]) { |
5c3376ef | 190 | _cleanup_(sd_event_unrefp) sd_event *event; |
1d03c5c1 | 191 | _cleanup_(clock_state_release) ClockState state = { |
2dd79846 PB |
192 | .timerfd_fd = -1, |
193 | .inotify_fd = -1, | |
194 | .run_systemd_wd = -1, | |
195 | .run_systemd_timesync_wd = -1, | |
5c3376ef | 196 | }; |
1d03c5c1 | 197 | int r; |
5c3376ef PB |
198 | |
199 | assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, -1) >= 0); | |
200 | ||
201 | r = sd_event_default(&event); | |
1d03c5c1 YW |
202 | if (r < 0) |
203 | return log_error_errno(r, "Failed to allocate event loop: %m"); | |
5c3376ef PB |
204 | |
205 | r = sd_event_add_signal(event, NULL, SIGTERM, NULL, NULL); | |
1d03c5c1 YW |
206 | if (r < 0) |
207 | return log_error_errno(r, "Failed to create sigterm event source: %m"); | |
5c3376ef PB |
208 | |
209 | r = sd_event_add_signal(event, NULL, SIGINT, NULL, NULL); | |
1d03c5c1 YW |
210 | if (r < 0) |
211 | return log_error_errno(r, "Failed to create sigint event source: %m"); | |
5c3376ef PB |
212 | |
213 | r = sd_event_set_watchdog(event, true); | |
1d03c5c1 YW |
214 | if (r < 0) |
215 | return log_error_errno(r, "Failed to create watchdog event source: %m"); | |
5c3376ef | 216 | |
2dd79846 | 217 | r = inotify_init1(IN_NONBLOCK|IN_CLOEXEC); |
1d03c5c1 YW |
218 | if (r < 0) |
219 | return log_error_errno(errno, "Failed to create inotify descriptor: %m"); | |
220 | ||
2dd79846 PB |
221 | state.inotify_fd = r; |
222 | ||
223 | r = sd_event_add_io(event, &state.inotify_event_source, state.inotify_fd, | |
224 | EPOLLIN, inotify_handler, &state); | |
1d03c5c1 YW |
225 | if (r < 0) |
226 | return log_error_errno(r, "Failed to create notify event source: %m"); | |
2dd79846 | 227 | |
27c3112d | 228 | r = inotify_add_watch_and_warn(state.inotify_fd, "/run/systemd/", IN_CREATE); |
1d03c5c1 | 229 | if (r < 0) |
27c3112d | 230 | return r; |
1d03c5c1 | 231 | |
2dd79846 PB |
232 | state.run_systemd_wd = r; |
233 | ||
234 | (void) update_notify_run_systemd_timesync(&state); | |
235 | ||
5c3376ef PB |
236 | r = clock_state_update(&state, event); |
237 | if (r > 0) { | |
238 | r = sd_event_loop(event); | |
0fad9daf | 239 | if (r < 0) |
5c3376ef | 240 | log_error_errno(r, "Failed in event loop: %m"); |
5c3376ef PB |
241 | } |
242 | ||
2dd79846 | 243 | if (state.has_watchfile) |
5238e957 | 244 | log_debug("Exit enabled by: /run/systemd/timesync/synchronized"); |
2dd79846 PB |
245 | |
246 | if (state.adjtime_state == TIME_ERROR) | |
247 | log_info("Exit without adjtimex synchronized."); | |
248 | ||
1d03c5c1 | 249 | return r; |
5c3376ef | 250 | } |
1d03c5c1 YW |
251 | |
252 | DEFINE_MAIN_FUNCTION(run); |