From 78f9939afc1bd24f5c929bfc8a643bbffedb35c5 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Sun, 30 Jun 2024 20:46:40 +0200
Subject: [PATCH] Fix setting the clock by one hour back

---
 src/timedate.cpp | 29 +++++++++++------------------
 src/timedate.h   |  2 +-
 2 files changed, 12 insertions(+), 19 deletions(-)

diff --git a/src/timedate.cpp b/src/timedate.cpp
index c7c2406..509bb95 100644
--- a/src/timedate.cpp
+++ b/src/timedate.cpp
@@ -161,9 +161,6 @@ static void slack_get_property(Glib::VariantBase& result, const Glib::RefPtr<Gio
 
 namespace dlackware::timedate
 {
-    constexpr const std::uint64_t usec_per_sec = 1000000ULL;
-    constexpr const std::uint64_t nsec_per_usec = 1000ULL;
-
     timedate1::timedate1()
         : interface_vtable{ &slack_method_call, &slack_get_property }
     {
@@ -279,30 +276,26 @@ namespace dlackware::timedate
         }
     }
 
-    void set_time(std::int64_t seconds_since_epoch, bool relative, bool)
+    void set_time(std::int64_t usec_utc, bool relative, bool)
     {
         timespec ts;
+        std::chrono::system_clock::duration current_time_since_epoch;
 
         if (relative)
         {
-            if (clock_gettime(CLOCK_REALTIME, &ts) == -1)
-            {
-                throw std::system_error(errno, std::generic_category());
-            }
-            ts.tv_sec += static_cast<time_t>(seconds_since_epoch / dlackware::timedate::usec_per_sec);
-            ts.tv_nsec += (seconds_since_epoch % dlackware::timedate::usec_per_sec) * dlackware::timedate::nsec_per_usec;
-
-            if (ts.tv_nsec < 0)
-            {
-                --ts.tv_sec;
-                ts.tv_nsec += dlackware::timedate::usec_per_sec;
-            }
+            current_time_since_epoch = std::chrono::system_clock::now().time_since_epoch();
+            current_time_since_epoch += std::chrono::microseconds(usec_utc);
         }
         else
         {
-            ts.tv_sec = static_cast<time_t>(seconds_since_epoch / dlackware::timedate::usec_per_sec);
-            ts.tv_nsec = (seconds_since_epoch % dlackware::timedate::usec_per_sec) * dlackware::timedate::nsec_per_usec;
+            current_time_since_epoch = std::chrono::microseconds(usec_utc);
         }
+        auto seconds_since_epoch = std::chrono::floor<std::chrono::seconds>(current_time_since_epoch);
+
+        ts.tv_sec = seconds_since_epoch.count();
+        ts.tv_nsec = std::chrono::duration_cast<std::chrono::microseconds>(
+                current_time_since_epoch - seconds_since_epoch).count();
+
         if (clock_settime(CLOCK_REALTIME, &ts) == -1)
         {
             throw std::system_error(errno, std::generic_category());
diff --git a/src/timedate.h b/src/timedate.h
index a1b2852..e197b4b 100644
--- a/src/timedate.h
+++ b/src/timedate.h
@@ -63,7 +63,7 @@ namespace dlackware::timedate
     // Changes the date/time
     // Takes the amount of seconds since UNIX epoche and 
     // Throws std::system_error.
-    void set_time(std::int64_t seconds_since_epoch, bool relative, bool user_interaction);
+    void set_time(std::int64_t usec_utc, bool relative, bool user_interaction);
 
     // Controls whether the RTC is local time or UTC.
     void set_local_rtc(bool local_rtc, bool fix_system, bool user_interaction);