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);
115 fd = open("/dev/rtc0", flags);
122 int hwclock_get_time(struct tm *tm) {
128 fd = rtc_open(O_RDONLY|O_CLOEXEC);
132 /* This leaves the timezone fields of struct tm
134 if (ioctl(fd, RTC_RD_TIME, tm) < 0)
137 /* We don't know daylight saving, so we reset this in order not
138 * to confused mktime(). */
141 close_nointr_nofail(fd);
146 int hwclock_set_time(const struct tm *tm) {
152 fd = rtc_open(O_RDONLY|O_CLOEXEC);
156 if (ioctl(fd, RTC_SET_TIME, tm) < 0)
159 close_nointr_nofail(fd);
164 int hwclock_is_localtime(void) {
169 * The third line of adjtime is "UTC" or "LOCAL" or nothing.
175 f = fopen("/etc/adjtime", "re");
180 b = fgets(line, sizeof(line), f) &&
181 fgets(line, sizeof(line), f) &&
182 fgets(line, sizeof(line), f);
190 local = streq(line, "LOCAL");
192 } else if (errno != -ENOENT)
198 int hwclock_set_timezone(int *min) {
199 const struct timeval *tv_null = NULL;
205 assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);
206 assert_se(tm = localtime(&ts.tv_sec));
207 minutesdelta = tm->tm_gmtoff / 60;
209 tz.tz_minuteswest = -minutesdelta;
210 tz.tz_dsttime = 0; /* DST_NONE*/
213 * If the hardware clock does not run in UTC, but in local time:
214 * The very first time we set the kernel's timezone, it will warp
215 * the clock so that it runs in UTC instead of local time.
217 if (settimeofday(tv_null, &tz) < 0)
224 int hwclock_reset_timezone(void) {
225 const struct timeval *tv_null = NULL;
228 tz.tz_minuteswest = 0;
229 tz.tz_dsttime = 0; /* DST_NONE*/
232 * The very first time we set the kernel's timezone, it will warp
233 * the clock. Do a dummy call here, so the time warping is sealed
234 * and we set only the time zone with next call.
236 if (settimeofday(tv_null, &tz) < 0)