display log and onscreen times in local timezone

src/RedirectablePrint.cpp

@@ -99,7 +99,7 @@ size_t RedirectablePrint::log(const char *logLevel, const char *format, ...)
 
         // If we are the first message on a report, include the header
         if (!isContinuationMessage) {
-            uint32_t rtc_sec = getValidTime(RTCQuality::RTCQualityDevice);
+            uint32_t rtc_sec = getValidTime(RTCQuality::RTCQualityDevice, true); // display local time on logfile
             if (rtc_sec > 0) {
                 long hms = rtc_sec % SEC_PER_DAY;
                 // hms += tz.tz_dsttime * SEC_PER_HOUR;

src/gps/RTC.cpp

@@ -128,7 +128,7 @@ bool perhapsSetRTC(RTCQuality q, const struct timeval *tv)
 #else
             rtc.initI2C();
 #endif
-            tm *t = localtime(&tv->tv_sec);
+            tm *t = gmtime(&tv->tv_sec);
             rtc.setTime(t->tm_year + 1900, t->tm_mon + 1, t->tm_wday, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec);
             LOG_DEBUG("RV3028_RTC setTime %02d-%02d-%02d %02d:%02d:%02d %ld\n", t->tm_year + 1900, t->tm_mon + 1, t->tm_mday,
                       t->tm_hour, t->tm_min, t->tm_sec, tv->tv_sec);
@@ -142,7 +142,7 @@ bool perhapsSetRTC(RTCQuality q, const struct timeval *tv)
 #else
             rtc.begin();
 #endif
-            tm *t = localtime(&tv->tv_sec);
+            tm *t = gmtime(&tv->tv_sec);
             rtc.setDateTime(t->tm_year + 1900, t->tm_mon + 1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec);
             LOG_DEBUG("PCF8563_RTC setDateTime %02d-%02d-%02d %02d:%02d:%02d %ld\n", t->tm_year + 1900, t->tm_mon + 1, t->tm_mday,
                       t->tm_hour, t->tm_min, t->tm_sec, tv->tv_sec);
@@ -175,7 +175,15 @@ bool perhapsSetRTC(RTCQuality q, struct tm &t)
     The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of seconds that have elapsed since January 1, 1970
     (midnight UTC/GMT), not counting leap seconds (in ISO 8601: 1970-01-01T00:00:00Z).
     */
+    // horrible hack to make mktime TZ agnostic - best practise according to
+    // https://www.gnu.org/software/libc/manual/html_node/Broken_002ddown-Time.html
+    setenv("TZ", "GMT0", 1);
     time_t res = mktime(&t);
+    if (*config.device.tzdef) {
+        setenv("TZ", config.device.tzdef, 1);
+    } else {
+        setenv("TZ", "UTC0", 1);
+    }
     struct timeval tv;
     tv.tv_sec = res;
     tv.tv_usec = 0; // time.centisecond() * (10 / 1000);
@@ -189,14 +197,33 @@ bool perhapsSetRTC(RTCQuality q, struct tm &t)
     }
 }
 
+/**
+ * Returns the timezone offset in seconds.
+ *
+ * @return The timezone offset in seconds.
+ */
+int32_t getTZOffset()
+{
+    time_t now;
+    struct tm *gmt;
+    now = time(NULL);
+    gmt = gmtime(&now);
+    gmt->tm_isdst = -1;
+    return (int16_t)difftime(now, mktime(gmt));
+}
+
 /**
  * Returns the current time in seconds since the Unix epoch (January 1, 1970).
  *
  * @return The current time in seconds since the Unix epoch.
  */
-uint32_t getTime()
+uint32_t getTime(bool local)
 {
-    return (((uint32_t)millis() - timeStartMsec) / 1000) + zeroOffsetSecs;
+    if (local) {
+        return (((uint32_t)millis() - timeStartMsec) / 1000) + zeroOffsetSecs + getTZOffset();
+    } else {
+        return (((uint32_t)millis() - timeStartMsec) / 1000) + zeroOffsetSecs;
+    }
 }
 
 /**
@@ -205,7 +232,7 @@ uint32_t getTime()
  * @param minQuality The minimum quality of the RTC time required for it to be considered valid.
  * @return The current time from the RTC if it meets the minimum quality requirement, or 0 if the time is not valid.
  */
-uint32_t getValidTime(RTCQuality minQuality)
+uint32_t getValidTime(RTCQuality minQuality, bool local)
 {
-    return (currentQuality >= minQuality) ? getTime() : 0;
+    return (currentQuality >= minQuality) ? getTime(local) : 0;
 }

src/gps/RTC.h

@@ -29,10 +29,10 @@ bool perhapsSetRTC(RTCQuality q, const struct timeval *tv);
 bool perhapsSetRTC(RTCQuality q, struct tm &t);
 
 /// Return time since 1970 in secs.  While quality is RTCQualityNone we will be returning time based at zero
-uint32_t getTime();
+uint32_t getTime(bool local = false);
 
 /// Return time since 1970 in secs.  If quality is RTCQualityNone return zero
-uint32_t getValidTime(RTCQuality minQuality);
+uint32_t getValidTime(RTCQuality minQuality, bool local = false);
 
 void readFromRTC();
 

src/graphics/Screen.cpp

@@ -1896,7 +1896,7 @@ void DebugInfo::drawFrameSettings(OLEDDisplay *display, OLEDDisplayUiState *stat
     // Show uptime as days, hours, minutes OR seconds
     std::string uptime = screen->drawTimeDelta(days, hours, minutes, seconds);
 
-    uint32_t rtc_sec = getValidTime(RTCQuality::RTCQualityDevice);
+    uint32_t rtc_sec = getValidTime(RTCQuality::RTCQualityDevice, true); // Display local timezone
     if (rtc_sec > 0) {
         long hms = rtc_sec % SEC_PER_DAY;
         // hms += tz.tz_dsttime * SEC_PER_HOUR;

src/main.cpp

@@ -663,6 +663,15 @@ void setup()
     // Initialize the screen first so we can show the logo while we start up everything else.
     screen = new graphics::Screen(screen_found, screen_model, screen_geometry);
 
+    // setup TZ prior to time actions.
+    if (*config.device.tzdef) {
+        setenv("TZ", config.device.tzdef, 1);
+    } else {
+        setenv("TZ", "GMT0", 1);
+    }
+    tzset();
+    LOG_DEBUG("Set Timezone to %s\n", getenv("TZ"));
+
     readFromRTC(); // read the main CPU RTC at first (in case we can't get GPS time)
 
 #if !MESHTASTIC_EXCLUDE_GPS