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git.ipfire.org Git - thirdparty/systemd.git/blob - src/timesync/timesyncd.c
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1 /* SPDX-License-Identifier: LGPL-2.1+ */
3 This file is part of systemd.
5 Copyright 2014 Kay Sievers, Lennart Poettering
7 systemd is free software; you can redistribute it and/or modify it
8 under the terms of the GNU Lesser General Public License as published by
9 the Free Software Foundation; either version 2.1 of the License, or
10 (at your option) any later version.
12 systemd is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public License
18 along with systemd; If not, see <http://www.gnu.org/licenses/>.
21 #include "sd-daemon.h"
24 #include "capability-util.h"
25 #include "clock-util.h"
29 #include "network-util.h"
30 #include "process-util.h"
31 #include "signal-util.h"
32 #include "timesyncd-conf.h"
33 #include "timesyncd-manager.h"
34 #include "user-util.h"
36 static int load_clock_timestamp(uid_t uid
, gid_t gid
) {
37 _cleanup_close_
int fd
= -1;
38 usec_t min
= TIME_EPOCH
* USEC_PER_SEC
;
42 /* Let's try to make sure that the clock is always
43 * monotonically increasing, by saving the clock whenever we
44 * have a new NTP time, or when we shut down, and restoring it
45 * when we start again. This is particularly helpful on
46 * systems lacking a battery backed RTC. We also will adjust
47 * the time to at least the build time of systemd. */
49 fd
= open("/var/lib/systemd/timesync/clock", O_RDWR
|O_CLOEXEC
, 0644);
54 /* check if the recorded time is later than the compiled-in one */
57 stamp
= timespec_load(&st
.st_mtim
);
63 /* Try to fix the access mode, so that we can still
64 touch the file after dropping priviliges */
67 return log_error_errno(errno
, "Failed to change file access mode: %m");
68 r
= fchown(fd
, uid
, gid
);
70 return log_error_errno(errno
, "Failed to change file owner: %m");
74 r
= mkdir_safe_label("/var/lib/systemd/timesync", 0755, uid
, gid
, MKDIR_FOLLOW_SYMLINK
);
76 return log_error_errno(r
, "Failed to create state directory: %m");
78 /* create stamp file with the compiled-in date */
79 (void) touch_file("/var/lib/systemd/timesync/clock", false, min
, uid
, gid
, 0644);
82 ct
= now(CLOCK_REALTIME
);
85 char date
[FORMAT_TIMESTAMP_MAX
];
87 log_info("System clock time unset or jumped backwards, restoring from recorded timestamp: %s",
88 format_timestamp(date
, sizeof(date
), min
));
90 if (clock_settime(CLOCK_REALTIME
, timespec_store(&ts
, min
)) < 0)
91 log_error_errno(errno
, "Failed to restore system clock: %m");
97 int main(int argc
, char *argv
[]) {
98 _cleanup_(manager_freep
) Manager
*m
= NULL
;
99 const char *user
= "systemd-timesync";
100 uid_t uid
, uid_current
;
104 log_set_target(LOG_TARGET_AUTO
);
105 log_set_facility(LOG_CRON
);
106 log_parse_environment();
112 log_error("This program does not take arguments.");
117 uid
= uid_current
= geteuid();
120 if (uid_current
== 0) {
121 r
= get_user_creds(&user
, &uid
, &gid
, NULL
, NULL
);
123 log_error_errno(r
, "Cannot resolve user name %s: %m", user
);
128 r
= load_clock_timestamp(uid
, gid
);
132 /* Drop privileges, but only if we have been started as root. If we are not running as root we assume all
133 * privileges are already dropped. */
134 if (uid_current
== 0) {
135 r
= drop_privileges(uid
, gid
, (1ULL << CAP_SYS_TIME
));
140 assert_se(sigprocmask_many(SIG_BLOCK
, NULL
, SIGTERM
, SIGINT
, -1) >= 0);
144 log_error_errno(r
, "Failed to allocate manager: %m");
148 if (clock_is_localtime(NULL
) > 0) {
149 log_info("The system is configured to read the RTC time in the local time zone. "
150 "This mode cannot be fully supported. All system time to RTC updates are disabled.");
151 m
->rtc_local_time
= true;
154 r
= manager_parse_config_file(m
);
156 log_warning_errno(r
, "Failed to parse configuration file: %m");
158 r
= manager_parse_fallback_string(m
, NTP_SERVERS
);
160 log_error_errno(r
, "Failed to parse fallback server strings: %m");
164 log_debug("systemd-timesyncd running as pid " PID_FMT
, getpid_cached());
167 "STATUS=Daemon is running");
169 if (network_is_online()) {
170 r
= manager_connect(m
);
175 r
= sd_event_loop(m
->event
);
177 log_error_errno(r
, "Failed to run event loop: %m");
181 /* if we got an authoritative time, store it in the file system */
183 (void) touch("/var/lib/systemd/timesync/clock");
185 sd_event_get_exit_code(m
->event
, &r
);
190 "STATUS=Shutting down...");
192 return r
< 0 ? EXIT_FAILURE
: EXIT_SUCCESS
;