fix(simu): use local time rather than UTC in the WASM simulator (#7658)

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

companion/src/simulation/wasmsimulatorinterface.cpp

@@ -15,6 +15,7 @@
 
 #include "wasmsimulatorinterface.h"
 
+#include <QDateTime>
 #include <QDebug>
 #include <QFile>
 #include <QElapsedTimer>
@@ -559,8 +560,11 @@ void WasmSimulatorInterface::start(const char * filename, bool tests)
     }
   }
 
-  uint32_t argv[1] = {(uint32_t)tests};
-  if (!wasm_runtime_call_wasm(m_execEnv, m_fnStart, 1, argv)) {
+  // WASI has no timezone support, so the module needs our UTC offset.
+  uint32_t argv[2] = {
+      (uint32_t)tests,
+      (uint32_t)(int32_t)QDateTime::currentDateTime().offsetFromUtc()};
+  if (!wasm_runtime_call_wasm(m_execEnv, m_fnStart, 2, argv)) {
     qWarning() << "WASM simuStart failed:"
                << wasm_runtime_get_exception(m_moduleInst);
     return;

radio/src/targets/simu/simufatfs.cpp

@@ -208,14 +208,14 @@ FRESULT file_stat(const std::string& realPath, FILINFO* fno)
     if (!ec) {
       auto systime = ftime_to_systime(ftime);
       auto time_t_val = std::chrono::system_clock::to_time_t(systime);
-      struct tm* ltime = localtime(&time_t_val);
+      struct tm ltime;
 
-      if (ltime) {
+      if (simuLocalTime(time_t_val, &ltime)) {
         // Convert to FatFs format
-        fno->fdate = ((ltime->tm_year - 80) << 9) | ((ltime->tm_mon + 1) << 5) |
-                     ltime->tm_mday;
+        fno->fdate = ((ltime.tm_year - 80) << 9) | ((ltime.tm_mon + 1) << 5) |
+                     ltime.tm_mday;
         fno->ftime =
-            (ltime->tm_hour << 11) | (ltime->tm_min << 5) | (ltime->tm_sec / 2);
+            (ltime.tm_hour << 11) | (ltime.tm_min << 5) | (ltime.tm_sec / 2);
       } else {
         fno->fdate = 0;
         fno->ftime = 0;
@@ -572,7 +572,7 @@ FRESULT f_utime(const TCHAR* path, const FILINFO* fno)
     ltime.tm_sec = (fno->ftime & 0x1F) * 2;
     ltime.tm_isdst = -1;
 
-    time_t timestamp = mktime(&ltime);
+    time_t timestamp = simuLocalTimeToEpoch(&ltime);
     if (timestamp == -1) {
         return FR_INVALID_PARAMETER;
     }

radio/src/targets/simu/simulib.cpp

@@ -142,11 +142,46 @@ void simuCreateDefaults()
   simuCreateDefaultSettings = true;
 }
 
-void simuStart(bool tests)
+#if defined(__wasm__)
+static int32_t simuUtcOffset = 0;
+#endif
+
+bool simuLocalTime(time_t t, struct tm* result)
+{
+  struct tm* tmp;
+#if defined(__wasm__)
+  t += simuUtcOffset;
+  tmp = gmtime(&t);
+#else
+  tmp = localtime(&t);
+#endif
+  if (tmp == nullptr) return false;
+  *result = *tmp;
+  return true;
+}
+
+time_t simuLocalTimeToEpoch(struct tm* tm)
+{
+#if defined(__wasm__)
+  // wasi-libc's mktime() is timezone-less, i.e. equivalent to timegm()
+  time_t t = mktime(tm);
+  return t == (time_t)-1 ? t : t - simuUtcOffset;
+#else
+  return mktime(tm);
+#endif
+}
+
+void simuStart(bool tests, int32_t utcOffset)
 {
   if (simu_running)
     return;
 
+#if defined(__wasm__)
+  simuUtcOffset = utcOffset;
+#else
+  (void)utcOffset;
+#endif
+
 #if !defined(COLORLCD)
   menuLevel = 0;
 #endif
@@ -171,20 +206,19 @@ void simuStart(bool tests)
 
 #if defined(RTCLOCK)
   time_t rawtime;
-  struct tm * timeinfo;
+  struct tm timeinfo;
   time (&rawtime);
-  timeinfo = localtime (&rawtime);
 
-  if (timeinfo != nullptr) {
+  if (simuLocalTime(rawtime, &timeinfo)) {
     struct gtm gti;
-    gti.tm_sec  = timeinfo->tm_sec;
-    gti.tm_min  = timeinfo->tm_min;
-    gti.tm_hour = timeinfo->tm_hour;
-    gti.tm_mday = timeinfo->tm_mday;
-    gti.tm_mon  = timeinfo->tm_mon;
-    gti.tm_year = timeinfo->tm_year;
-    gti.tm_wday = timeinfo->tm_wday;
-    gti.tm_yday = timeinfo->tm_yday;
+    gti.tm_sec  = timeinfo.tm_sec;
+    gti.tm_min  = timeinfo.tm_min;
+    gti.tm_hour = timeinfo.tm_hour;
+    gti.tm_mday = timeinfo.tm_mday;
+    gti.tm_mon  = timeinfo.tm_mon;
+    gti.tm_year = timeinfo.tm_year;
+    gti.tm_wday = timeinfo.tm_wday;
+    gti.tm_yday = timeinfo.tm_yday;
     g_rtcTime = gmktime(&gti);
   } else {
     g_rtcTime = rawtime;

radio/src/targets/simu/simulib.h

@@ -24,6 +24,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stddef.h>
+#include <time.h>
 
 #include <string>
 
@@ -43,8 +44,10 @@
 
 // Lifecycle: call simuInit() once, then simuFatfsSetPaths() + simuStart().
 // Poll simuIsRunning() periodically. Call simuStop() to shut down.
+// utcOffset: seconds east of UTC, DST applied; wasi-libc's localtime() always
+// reports UTC. Ignored by native builds.
 void WASM_EXPORT(simuInit)();
-void WASM_EXPORT(simuStart)(bool tests = true);
+void WASM_EXPORT(simuStart)(bool tests = true, int32_t utcOffset = 0);
 void WASM_EXPORT(simuStop)();
 bool WASM_EXPORT(simuIsRunning)();
 
@@ -189,6 +192,11 @@ void WASM_IMPORT(simuAuxSerialSendBuffer)(uint8_t port_nr, const uint8_t* data,
                                          uint32_t len);
 
 // -- Internal (not exported) --
+
+// Use instead of localtime()/mktime(): applies simuStart()'s utcOffset on WASM.
+bool simuLocalTime(time_t t, struct tm* result);
+time_t simuLocalTimeToEpoch(struct tm* tm);
+
 void simuMain();
 std::string simuFatfsGetCurrentPath();
 std::string simuFatfsGetRealPath(const std::string& p);

web/src/App.svelte

@@ -448,7 +448,8 @@
       ex.simuInit();
       runner.setFatfsPaths('/', '/');
       ex.simuCreateDefaults();
-      ex.simuStart(1);
+      // WASI has no timezone support, so the module needs our UTC offset.
+      ex.simuStart(1, -new Date().getTimezoneOffset() * 60);
 
       if (canvas) {
         lcdRenderer = new LcdRenderer(canvas);

web/src/lib/wasm-runner.ts

@@ -45,7 +45,7 @@ export interface SimulatorExports {
   free: (ptr: number) => void;
 
   simuInit: () => void;
-  simuStart: (tests: number) => void;
+  simuStart: (tests: number, utcOffset: number) => void;
   simuStop: () => void;
   simuIsRunning: () => number;
   simuFatfsSetPaths: (sdPath: number, settingsPath: number) => void;