1 files changed, 142 insertions, 0 deletions
diff --git a/src/basic/clock-util.c b/src/basic/clock-util.c
new file mode 100644
index 0000000000..e4e03df1e4
--- /dev/null
+++ b/src/basic/clock-util.c
@@ -0,0 +1,142 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010-2012 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+#include <linux/rtc.h>
+
+#include "macro.h"
+#include "util.h"
+#include "clock-util.h"
+
+int clock_get_hwclock(struct tm *tm) {
+        _cleanup_close_ int fd = -1;
+
+        assert(tm);
+
+        fd = open("/dev/rtc", O_RDONLY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        /* This leaves the timezone fields of struct tm
+         * uninitialized! */
+        if (ioctl(fd, RTC_RD_TIME, tm) < 0)
+                return -errno;
+
+        /* We don't know daylight saving, so we reset this in order not
+         * to confuse mktime(). */
+        tm->tm_isdst = -1;
+
+        return 0;
+}
+
+int clock_set_hwclock(const struct tm *tm) {
+        _cleanup_close_ int fd = -1;
+
+        assert(tm);
+
+        fd = open("/dev/rtc", O_RDONLY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        if (ioctl(fd, RTC_SET_TIME, tm) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int clock_is_localtime(void) {
+        _cleanup_fclose_ FILE *f;
+
+        /*
+         * The third line of adjtime is "UTC" or "LOCAL" or nothing.
+         *   # /etc/adjtime
+         *   0.0 0 0
+         *   0
+         *   UTC
+         */
+        f = fopen("/etc/adjtime", "re");
+        if (f) {
+                char line[LINE_MAX];
+                bool b;
+
+                b = fgets(line, sizeof(line), f) &&
+                        fgets(line, sizeof(line), f) &&
+                        fgets(line, sizeof(line), f);
+                if (!b)
+                        return -EIO;
+
+                truncate_nl(line);
+                return streq(line, "LOCAL");
+
+        } else if (errno != ENOENT)
+                return -errno;
+
+        return 0;
+}
+
+int clock_set_timezone(int *min) {
+        const struct timeval *tv_null = NULL;
+        struct timespec ts;
+        struct tm *tm;
+        int minutesdelta;
+        struct timezone tz;
+
+        assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);
+        assert_se(tm = localtime(&ts.tv_sec));
+        minutesdelta = tm->tm_gmtoff / 60;
+
+        tz.tz_minuteswest = -minutesdelta;
+        tz.tz_dsttime = 0; /* DST_NONE */
+
+        /*
+         * If the RTC does not run in UTC but in local time, the very first
+         * call to settimeofday() will set the kernel's timezone and will warp the
+         * system clock, so that it runs in UTC instead of the local time we
+         * have read from the RTC.
+         */
+        if (settimeofday(tv_null, &tz) < 0)
+                return -errno;
+        if (min)
+                *min = minutesdelta;
+        return 0;
+}
+
+int clock_reset_timewarp(void) {
+        const struct timeval *tv_null = NULL;
+        struct timezone tz;
+
+        tz.tz_minuteswest = 0;
+        tz.tz_dsttime = 0; /* DST_NONE */
+
+        /*
+         * The very first call to settimeofday() does time warp magic. Do a
+         * dummy call here, so the time warping is sealed and all later calls
+         * behave as expected.
+         */
+        if (settimeofday(tv_null, &tz) < 0)
+                return -errno;
+
+        return 0;
+}