Fix getTimezoneOffset() when tm_gmtoff is not available

quickjs.c

@@ -40493,38 +40493,31 @@ static const JSCFunctionListEntry js_math_obj[] = {
 
 /* OS dependent. d = argv[0] is in ms from 1970. Return the difference
    between UTC time and local time 'd' in minutes */
-static int getTimezoneOffset(int64_t time) {
+static int getTimezoneOffset() {
 #if defined(_WIN32)
     /* XXX: TODO */
     return 0;
 #else
-    time_t ti;
-    struct tm tm;
-
-    time /= 1000; /* convert to seconds */
-    if (sizeof(time_t) == 4) {
-        /* on 32-bit systems, we need to clamp the time value to the
-           range of `time_t`. This is better than truncating values to
-           32 bits and hopefully provides the same result as 64-bit
-           implementation of localtime_r.
-         */
-        if ((time_t)-1 < 0) {
-            if (time < INT32_MIN) {
-                time = INT32_MIN;
-            } else if (time > INT32_MAX) {
-                time = INT32_MAX;
-            }
-        } else {
-            if (time < 0) {
-                time = 0;
-            } else if (time > UINT32_MAX) {
-                time = UINT32_MAX;
-            }
-        }
+    time_t unixTime = time(NULL);
+
+    struct tm* localTime = localtime(&unixTime);
+    time_t localTimeNum = mktime(localTime);
+
+    struct tm *gmtTime = gmtime(&unixTime);
+    time_t gmtTimeNum = mktime(gmtTime);
+
+    // Calculate the time zone offset in minutes
+    int timeZoneOffset = (int)difftime(localTimeNum, gmtTimeNum) / 60;
+
+    // In JavaScript, it's the opposite
+    timeZoneOffset = -timeZoneOffset;
+
+    // Take off another hour if daylight savings it active
+    if (localTime->tm_isdst) {
+        timeZoneOffset = timeZoneOffset - 60;
     }
-    ti = time;
-    localtime_r(&ti, &tm);
-    return -tm.tm_gmtoff / 60;
+
+    return timeZoneOffset;
 #endif
 }
 
@@ -46531,7 +46524,7 @@ static __exception int get_date_fields(JSContext *ctx, JSValue obj,
     } else {
         d = dval;
         if (is_local) {
-            tz = -getTimezoneOffset(d);
+            tz = -getTimezoneOffset();
             d += tz * 60000;
         }
     }
@@ -46600,7 +46593,7 @@ static double set_date_fields(double fields[], int is_local) {
         fields[5] * 1000 + fields[6];
     d = days * 86400000 + h;
     if (is_local)
-        d += getTimezoneOffset(d) * 60000;
+        d += getTimezoneOffset() * 60000;
     return time_clip(d);
 }
 
@@ -47203,15 +47196,14 @@ static JSValue js_date_Symbol_toPrimitive(JSContext *ctx, JSValue this_val,
 static JSValue js_date_getTimezoneOffset(JSContext *ctx, JSValue this_val,
                                          int argc, JSValue *argv)
 {
-    // getTimezoneOffset()
     double v;
 
     if (JS_ThisTimeValue(ctx, &v, this_val))
         return JS_EXCEPTION;
     if (isnan(v))
         return JS_NAN;
     else
-        return JS_NewInt64(ctx, getTimezoneOffset((int64_t)trunc(v)));
+        return JS_NewInt64(ctx, getTimezoneOffset());
 }
 
 static JSValue js_date_getTime(JSContext *ctx, JSValue this_val,