1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2010-2012 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/>.
29 #include <sys/types.h>
32 #include <sys/ioctl.h>
35 #include <sys/prctl.h>
37 #include <linux/rtc.h>
45 static int rtc_open(int flags) {
49 /* First, we try to make use of the /dev/rtc symlink. If that
50 * doesn't exist, we open the first RTC which has hctosys=1
51 * set. If we don't find any we just take the first RTC that
54 fd = open("/dev/rtc", flags);
58 d = opendir("/sys/class/rtc");
65 union dirent_storage buf;
68 r = readdir_r(d, &buf.de, &de);
75 if (ignore_file(de->d_name))
78 p = strjoin("/sys/class/rtc/", de->d_name, "/hctosys", NULL);
84 r = read_one_line_file(p, &v);
96 p = strappend("/dev/", de->d_name);
110 fd = open("/dev/rtc0", flags);
117 int hwclock_get_time(struct tm *tm) {
123 fd = rtc_open(O_RDONLY|O_CLOEXEC);
127 /* This leaves the timezone fields of struct tm
129 if (ioctl(fd, RTC_RD_TIME, tm) < 0)
132 /* We don't know daylight saving, so we reset this in order not
133 * to confused mktime(). */
136 close_nointr_nofail(fd);
141 int hwclock_set_time(const struct tm *tm) {
147 fd = rtc_open(O_RDONLY|O_CLOEXEC);
151 if (ioctl(fd, RTC_SET_TIME, tm) < 0)
154 close_nointr_nofail(fd);
159 int hwclock_is_localtime(void) {
164 * The third line of adjtime is "UTC" or "LOCAL" or nothing.
170 f = fopen("/etc/adjtime", "re");
175 b = fgets(line, sizeof(line), f) &&
176 fgets(line, sizeof(line), f) &&
177 fgets(line, sizeof(line), f);
185 local = streq(line, "LOCAL");
187 } else if (errno != -ENOENT)
193 int hwclock_set_timezone(int *min) {
194 const struct timeval *tv_null = NULL;
200 assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);
201 assert_se(tm = localtime(&ts.tv_sec));
202 minuteswest = tm->tm_gmtoff / 60;
204 tz.tz_minuteswest = -minuteswest;
205 tz.tz_dsttime = 0; /* DST_NONE*/
208 * If the hardware clock does not run in UTC, but in local time:
209 * The very first time we set the kernel's timezone, it will warp
210 * the clock so that it runs in UTC instead of local time.
212 if (settimeofday(tv_null, &tz) < 0)
219 int hwclock_reset_timezone(void) {
220 const struct timeval *tv_null = NULL;
223 tz.tz_minuteswest = 0;
224 tz.tz_dsttime = 0; /* DST_NONE*/
227 * The very first time we set the kernel's timezone, it will warp
228 * the clock. Do a dummy call here, so the time warping is sealed
229 * and we set only the time zone with next call.
231 if (settimeofday(tv_null, &tz) < 0)