#2882: another attempt at fixing it that should also work on other platforms

Foundation/include/Poco/Timezone.h

@@ -38,6 +38,11 @@ public:
 		/// daylight saving time is in use.
 		///     local time = UTC + utcOffset() + dst().
 
+	static int dst(const Poco::Timestamp& timestamp);
+		/// Returns the daylight saving time offset in seconds if
+		/// daylight saving time is in use for the given time.
+		///     local time = UTC + utcOffset() + dst().
+
 	static bool isDst(const Timestamp& timestamp);
 		/// Returns true if daylight saving time is in effect
 		/// for the given time. Depending on the operating system
@@ -58,18 +63,6 @@ public:
 
 	static std::string dstName();
 		/// Returns the timezone name if daylight saving time is in effect.
-
-#if !defined(POCO_OS_FAMILY_WINDOWS)
-	static int utcOffset(const Poco::Timestamp& timestamp);
-		/// Returns the offset of local time to UTC
-		/// for the given time, in seconds.
-		///     local time = UTC + utcOffset() + dst().
-
-	static int dst(const Poco::Timestamp& timestamp);
-		/// Returns the daylight saving time offset in seconds if
-		/// daylight saving time is in use for the given time.
-		///     local time = UTC + utcOffset() + dst().
-#endif
 };
 
 

Foundation/src/LocalDateTime.cpp

@@ -277,7 +277,7 @@ void LocalDateTime::determineTzd(bool adjust)
  		if (err) broken = nullptr;
 #endif
 		if (!broken) throw Poco::SystemException("cannot get local time");
-		_tzd = (Timezone::utcOffset() + Timezone::dst(_dateTime.timestamp()));
+		_tzd = Timezone::utcOffset() + Timezone::dst(_dateTime.timestamp());
 #else
 		std::tm broken;
 #if defined(POCO_VXWORKS) && (defined(_VXWORKS_COMPATIBILITY_MODE) || (defined(_WRS_VXWORKS_MAJOR) && ((_WRS_VXWORKS_MAJOR < 6) || ((_WRS_VXWORKS_MAJOR == 6)  && (_WRS_VXWORKS_MINOR < 9)))))
@@ -287,7 +287,7 @@ void LocalDateTime::determineTzd(bool adjust)
 		if (!localtime_r(&epochTime, &broken))
 			throw Poco::SystemException("cannot get local time");
 #endif
-		_tzd = (Timezone::utcOffset() + ((broken.tm_isdst == 1) ? 3600 : 0));
+		_tzd = Timezone::utcOffset() + Timezone::dst(_dateTime.timestamp());
 #endif
 		adjustForTzd();
 	}
@@ -305,8 +305,8 @@ std::time_t LocalDateTime::dstOffset(int& dstOffset) const
 	std::time_t local;
 	std::tm     broken;
 
-	broken.tm_year  = (_dateTime.year() - 1900);
+	broken.tm_year  = _dateTime.year() - 1900;
-	broken.tm_mon   = (_dateTime.month() - 1);
+	broken.tm_mon   = _dateTime.month() - 1;
 	broken.tm_mday  = _dateTime.day();
 	broken.tm_hour  = _dateTime.hour();
 	broken.tm_min   = _dateTime.minute();

Foundation/src/Timezone_UNIX.cpp

@@ -29,12 +29,22 @@ public:
 		tzset();
 	}
 
-	static long gmtOffset(const struct std::tm& t)
+	int timeZone()
 	{
-	#if defined(__CYGWIN__)
+		Poco::FastMutex::ScopedLock lock(_mutex);
-		return t.__TM_GMTOFF;
+
+	#if defined(__APPLE__)  || defined(__FreeBSD__) || defined (__OpenBSD__) || POCO_OS == POCO_OS_ANDROID // no timezone global var
+		std::time_t now = std::time(NULL);
+		struct std::tm t;
+		gmtime_r(&now, &t);
+		std::time_t utc = std::mktime(&t);
+		return now - utc;
+	#elif defined(__CYGWIN__)
+		tzset();
+		return -_timezone;
 	#else
-		return t.tm_gmtoff;
+		tzset();
+		return -timezone;
 	#endif
 	}
 
@@ -54,22 +64,9 @@ private:
 static TZInfo tzInfo;
 
 
-int Timezone::utcOffset(const Poco::Timestamp& timestamp)
-{
-	std::time_t time = timestamp.epochTime();
-	struct std::tm local;
-	if (!localtime_r(&time, &local))
-		throw Poco::SystemException("cannot get UTC offset");
-	struct std::tm utc;
-	gmtime_r(&time, &utc);
-	std::time_t utctime = std::mktime(&utc);
-	return time - utctime;
-}
-
-
 int Timezone::utcOffset()
 {
-	return utcOffset(Poco::Timestamp());
+	return tzInfo.timeZone();
 }
 
 
@@ -85,8 +82,17 @@ int Timezone::dst(const Poco::Timestamp& timestamp)
 	struct std::tm local;
 	if (!localtime_r(&time, &local))
 		throw Poco::SystemException("cannot get local time DST offset");
-	long dst = TZInfo::gmtOffset(local) - utcOffset(timestamp);
+	if (local.tm_isdst > 0)
-	return local.tm_isdst == 1 ? dst : 0;
+	{
+#if defined(__CYGWIN__)
+		return local.__TM_GMTOFF - utcOffset();
+#elif defined(_BSD_SOURCE) || defined(__APPLE__)  || defined(__FreeBSD__) || defined (__OpenBSD__) || POCO_OS == POCO_OS_ANDROID
+		return local.tm_gmtoff - utcOffset();
+#else
+		return 3600;
+#endif
+	}
+	else return 0;
 }
 
 

Foundation/src/Timezone_VX.cpp

@@ -45,6 +45,12 @@ int Timezone::dst()
 }
 
 
+int Timezone::dst(const Poco::Timestamp& timestamp)
+{
+	return isDst(timestamp) ? 3600 : 0;
+}
+
+
 bool Timezone::isDst(const Timestamp& timestamp)
 {
 	std::time_t time = timestamp.epochTime();

Foundation/src/Timezone_WIN32.cpp

@@ -38,12 +38,39 @@ int Timezone::dst()
 }
 
 
+int Timezone::dst(const Poco::Timestamp& timestamp)
+{
+	if (isDst(timestamp))
+	{
+		TIME_ZONE_INFORMATION tzInfo;
+		GetTimeZoneInformation(&tzInfo);
+		return -tzInfo.DaylightBias*60;
+	}
+	else return 0;
+}
+
+
 bool Timezone::isDst(const Timestamp& timestamp)
 {
 	std::time_t time = timestamp.epochTime();
-	struct std::tm* tms = std::localtime(&time);
+	struct std::tm local;
-	if (!tms) throw Poco::SystemException("cannot get local time DST flag");
+	if (localtime_s(&local, &time))
-	return tms->tm_isdst > 0;
+		throw Poco::SystemException("cannot get local time DST flag");
+	return local.tm_isdst > 0;
+}
+
+
+int Timezone::utcOffset(const Poco::Timestamp& timestamp)
+{
+	std::time_t time = timestamp.epochTime();
+	struct tm local;
+	if (localtime_s(&local, &time))
+		throw Poco::SystemException("cannot get UTC offset");
+	struct tm utc;
+	if (gmtime_s(&utc, &time))
+		throw Poco::SystemException("cannot get UTC offset");
+	std::time_t utctime = std::mktime(&utc);
+	return time - utctime;
 }
 
 

Foundation/src/Timezone_WINCE.cpp

@@ -43,6 +43,18 @@ int Timezone::dst()
 }
 
 
+int Timezone::dst(const Poco::Timestamp& timestamp)
+{
+	if (isDst(timestamp))
+	{
+		TIME_ZONE_INFORMATION tzInfo;
+		GetTimeZoneInformation(&tzInfo);
+		return -tzInfo.DaylightBias*60;
+	}
+	else return 0;
+}
+
+
 bool Timezone::isDst(const Timestamp& timestamp)
 {
 	std::time_t time = timestamp.epochTime();