1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2014 Kay Sievers, Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
23 #include "sd-daemon.h"
24 #include "capability.h"
25 #include "clock-util.h"
26 #include "network-util.h"
28 #include "timesyncd-manager.h"
29 #include "timesyncd-conf.h"
31 static int load_clock_timestamp(uid_t uid, gid_t gid) {
32 _cleanup_close_ int fd = -1;
33 usec_t min = TIME_EPOCH * USEC_PER_SEC;
37 /* Let's try to make sure that the clock is always
38 * monotonically increasing, by saving the clock whenever we
39 * have a new NTP time, or when we shut down, and restoring it
40 * when we start again. This is particularly helpful on
41 * systems lacking a battery backed RTC. We also will adjust
42 * the time to at least the build time of systemd. */
44 fd = open("/var/lib/systemd/clock", O_RDWR|O_CLOEXEC, 0644);
49 /* check if the recorded time is later than the compiled-in one */
52 stamp = timespec_load(&st.st_mtim);
57 /* Try to fix the access mode, so that we can still
58 touch the file after dropping priviliges */
63 /* create stamp file with the compiled-in date */
64 touch_file("/var/lib/systemd/clock", true, min, uid, gid, 0644);
66 ct = now(CLOCK_REALTIME);
69 char date[FORMAT_TIMESTAMP_MAX];
71 log_info("System clock time unset or jumped backwards, restoring from recorded timestamp: %s",
72 format_timestamp(date, sizeof(date), min));
74 if (clock_settime(CLOCK_REALTIME, timespec_store(&ts, min)) < 0)
75 log_error_errno(errno, "Failed to restore system clock: %m");
81 int main(int argc, char *argv[]) {
82 _cleanup_(manager_freep) Manager *m = NULL;
83 const char *user = "systemd-timesync";
88 log_set_target(LOG_TARGET_AUTO);
89 log_set_facility(LOG_CRON);
90 log_parse_environment();
96 log_error("This program does not take arguments.");
101 r = get_user_creds(&user, &uid, &gid, NULL, NULL);
103 log_error_errno(r, "Cannot resolve user name %s: %m", user);
107 r = load_clock_timestamp(uid, gid);
111 r = drop_privileges(uid, gid, (1ULL << CAP_SYS_TIME));
115 /* We need one process for ourselves, plus one thread for the asynchronous resolver */
116 if (setrlimit(RLIMIT_NPROC, &RLIMIT_MAKE_CONST(2)) < 0)
117 log_warning_errno(errno, "Failed to lower RLIMIT_NPROC to 2: %m");
119 assert_se(sigprocmask_many(SIG_BLOCK, SIGTERM, SIGINT, -1) == 0);
123 log_error_errno(r, "Failed to allocate manager: %m");
127 if (clock_is_localtime() > 0) {
128 log_info("The system is configured to read the RTC time in the local time zone. "
129 "This mode can not be fully supported. All system time to RTC updates are disabled.");
130 m->rtc_local_time = true;
133 r = manager_parse_config_file(m);
135 log_warning_errno(r, "Failed to parse configuration file: %m");
137 log_debug("systemd-timesyncd running as pid %lu", (unsigned long) getpid());
140 "STATUS=Daemon is running");
142 if (network_is_online()) {
143 r = manager_connect(m);
148 r = sd_event_loop(m->event);
150 log_error_errno(r, "Failed to run event loop: %m");
154 /* if we got an authoritative time, store it in the file system */
156 touch("/var/lib/systemd/clock");
158 sd_event_get_exit_code(m->event, &r);
163 "STATUS=Shutting down...");
165 return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;