From 7948c4dfbea73ac21250b588089039aa17a90386 Mon Sep 17 00:00:00 2001
From: Kay Sievers <kay.sievers@vrfy.org>
Date: Tue, 24 May 2011 20:23:07 +0200
Subject: rtc in localtime: use settimeofday(NULL, tz) instead of hwclock(8)

We check for LOCAL in /etc/adjtime and if needed, ask the kernel to
apply the timezone delta to the system clock.

The very first call of settimeofday() without a time, but a timezone
warps the system clock, so that it properly runs in UTC.
---
 src/main.c |  7 ++++++
 src/util.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/util.h |  9 +++++++
 3 files changed, 96 insertions(+)

(limited to 'src')

diff --git a/src/main.c b/src/main.c
index 52b3031fbe..68328b76d3 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1049,6 +1049,13 @@ int main(int argc, char *argv[]) {
 
                 if (label_init() < 0)
                         goto finish;
+
+                if (hwclock_is_localtime()) {
+                        int min;
+
+                        min = hwclock_apply_localtime_delta();
+                        log_info("Hwclock configured in localtime, applying delta of %i minutes to system time", min);
+                }
         } else {
                 arg_running_as = MANAGER_USER;
                 log_set_target(LOG_TARGET_CONSOLE);
diff --git a/src/util.c b/src/util.c
index a271708ba2..4046938fcd 100644
--- a/src/util.c
+++ b/src/util.c
@@ -51,6 +51,8 @@
 #include <dlfcn.h>
 #include <sys/wait.h>
 #include <sys/capability.h>
+#include <sys/time.h>
+#include <linux/rtc.h>
 
 #include "macro.h"
 #include "util.h"
@@ -4761,3 +4763,81 @@ finish:
         *strv = files;
         return r;
 }
+
+bool hwclock_is_localtime(void) {
+        FILE *f;
+        char line[LINE_MAX];
+        bool local = false;
+
+        /*
+         * The third line of adjtime is "UTC" or "LOCAL" or nothing.
+         *   # /etc/adjtime
+         *   0.0 0 0.0
+         *   0
+         *   UTC
+         */
+        f = fopen("/etc/adjtime", "re");
+        if (f) {
+                if (fgets(line, sizeof(line), f) &&
+                    fgets(line, sizeof(line), f) &&
+                    fgets(line, sizeof(line), f) ) {
+                            if (!strcmp(line, "LOCAL\n"))
+                                 local = true;
+                }
+                fclose(f);
+        }
+        return local;
+}
+
+int hwclock_apply_localtime_delta(void) {
+        const struct timeval *tv_null = NULL;
+        struct timeval tv;
+        struct tm *tm;
+        int minuteswest;
+        struct timezone tz;
+
+        gettimeofday(&tv, NULL);
+        tm = localtime(&tv.tv_sec);
+        minuteswest = tm->tm_gmtoff / 60;
+
+        tz.tz_minuteswest = -minuteswest;
+        tz.tz_dsttime = 0; /* DST_NONE*/
+
+        /*
+         * If the hardware clock does not run in UTC, but in local time:
+         * The very first time we set the kernel's timezone, it will warp
+         * the clock so that it runs in UTC instead of local time.
+         */
+        if (settimeofday(tv_null, &tz) < 0)
+                return -errno;
+        else
+                return minuteswest;
+}
+
+int hwclock_get_time(struct tm *tm) {
+        int fd;
+        int err = 0;
+
+        fd = open("/dev/rtc0", O_RDONLY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+        if (ioctl(fd, RTC_RD_TIME, tm) < 0)
+                err = -errno;
+        close(fd);
+
+        return err;
+}
+
+int hwclock_set_time(const struct tm *tm) {
+        int fd;
+        int err = 0;
+
+        fd = open("/dev/rtc0", O_RDONLY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+        if (ioctl(fd, RTC_SET_TIME, tm) < 0)
+                err = -errno;
+        close(fd);
+
+        return err;
+}
diff --git a/src/util.h b/src/util.h
index 04049f7d92..79d634bb63 100644
--- a/src/util.h
+++ b/src/util.h
@@ -451,4 +451,13 @@ int signal_from_string(const char *s);
 int signal_from_string_try_harder(const char *s);
 
 int conf_files_list(char ***strv, const char *suffix, const char *dir, ...);
+
+bool hwclock_is_localtime(void);
+
+int hwclock_apply_localtime_delta(void);
+
+int hwclock_get_time(struct tm *tm);
+
+int hwclock_set_time(const struct tm *tm);
+
 #endif
-- 
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