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>
46 static int rtc_open(int flags) {
50 /* First, we try to make use of the /dev/rtc symlink. If that
51 * doesn't exist, we open the first RTC which has hctosys=1
52 * set. If we don't find any we just take the first RTC that
55 fd = open("/dev/rtc", flags);
59 d = opendir("/sys/class/rtc");
66 union dirent_storage buf;
69 r = readdir_r(d, &buf.de, &de);
76 if (ignore_file(de->d_name))
79 p = strjoin("/sys/class/rtc/", de->d_name, "/hctosys", NULL);
85 r = read_one_line_file(p, &v);
97 p = strappend("/dev/", de->d_name);
116 fd = open("/dev/rtc0", flags);
123 int hwclock_get_time(struct tm *tm) {
129 fd = rtc_open(O_RDONLY|O_CLOEXEC);
133 /* This leaves the timezone fields of struct tm
135 if (ioctl(fd, RTC_RD_TIME, tm) < 0)
138 /* We don't know daylight saving, so we reset this in order not
139 * to confused mktime(). */
142 close_nointr_nofail(fd);
147 int hwclock_set_time(const struct tm *tm) {
153 fd = rtc_open(O_RDONLY|O_CLOEXEC);
157 if (ioctl(fd, RTC_SET_TIME, tm) < 0)
160 close_nointr_nofail(fd);
165 int hwclock_is_localtime(void) {
166 FILE _cleanup_fclose_ *f;
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);
187 return streq(line, "LOCAL");
189 } else if (errno != ENOENT)
195 int hwclock_set_timezone(int *min) {
196 const struct timeval *tv_null = NULL;
202 assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);
203 assert_se(tm = localtime(&ts.tv_sec));
204 minutesdelta = tm->tm_gmtoff / 60;
206 tz.tz_minuteswest = -minutesdelta;
207 tz.tz_dsttime = 0; /* DST_NONE*/
210 * If the hardware clock does not run in UTC, but in local time:
211 * The very first time we set the kernel's timezone, it will warp
212 * the clock so that it runs in UTC instead of local time.
214 if (settimeofday(tv_null, &tz) < 0)
221 int hwclock_reset_timezone(void) {
222 const struct timeval *tv_null = NULL;
225 tz.tz_minuteswest = 0;
226 tz.tz_dsttime = 0; /* DST_NONE*/
229 * The very first time we set the kernel's timezone, it will warp
230 * the clock. Do a dummy call here, so the time warping is sealed
231 * and we set only the time zone with next call.
233 if (settimeofday(tv_null, &tz) < 0)