WinRT: Fix QTimeZone transitions by switching backend

Previously WinRT was using the UTC backend which fails on all platforms
for some QDateTime autotests related to timezone items. Hence switch to
the Windows implementation for WinRT as well.

However, the windows backend does query the registry heavily, which is
not supported on WinRT. Instead use the API version provided by the SDK.

Long-term we might want to switch to this version on desktop windows as
well, as direct registry access would not be required and we could
harmonize the codepaths for both platforms.

Change-Id: I620b614e9994aa77b531e5c34c9be1da7e272a30
Reviewed-by: Oliver Wolff <oliver.wolff@theqtcompany.com>

3 files changed, 105 insertions, 5 deletions

diff --git a/src/corelib/tools/qtimezone.cpp b/src/corelib/tools/qtimezone.cpp
index 333a5c3471..bf34a8b16f 100644
--- a/src/corelib/tools/qtimezone.cpp
+++ b/src/corelib/tools/qtimezone.cpp
@@ -61,7 +61,7 @@ static QTimeZonePrivate *newBackendTimeZone()
 #elif defined Q_OS_UNIX
     return new QTzTimeZonePrivate();
     // Registry based timezone backend not available on WinRT
-#elif defined Q_OS_WIN && !defined Q_OS_WINRT
+#elif defined Q_OS_WIN
     return new QWinTimeZonePrivate();
 #elif defined QT_USE_ICU
     return new QIcuTimeZonePrivate();
@@ -88,7 +88,7 @@ static QTimeZonePrivate *newBackendTimeZone(const QByteArray &ianaId)
 #elif defined Q_OS_UNIX
     return new QTzTimeZonePrivate(ianaId);
     // Registry based timezone backend not available on WinRT
-#elif defined Q_OS_WIN && !defined Q_OS_WINRT
+#elif defined Q_OS_WIN
     return new QWinTimeZonePrivate(ianaId);
 #elif defined QT_USE_ICU
     return new QIcuTimeZonePrivate(ianaId);
diff --git a/src/corelib/tools/qtimezoneprivate_win.cpp b/src/corelib/tools/qtimezoneprivate_win.cpp
index a9bb3aa3b5..0cb26c2e5b 100644
--- a/src/corelib/tools/qtimezoneprivate_win.cpp
+++ b/src/corelib/tools/qtimezoneprivate_win.cpp
@@ -42,6 +42,10 @@
 
 QT_BEGIN_NAMESPACE
 
+#ifndef Q_OS_WINRT
+#define QT_USE_REGISTRY_TIMEZONE 1
+#endif
+
 /*
     Private
 
@@ -59,9 +63,10 @@ QT_BEGIN_NAMESPACE
 
 // Vista introduced support for historic data, see MSDN docs on DYNAMIC_TIME_ZONE_INFORMATION
 // http://msdn.microsoft.com/en-gb/library/windows/desktop/ms724253%28v=vs.85%29.aspx
-
+#ifdef QT_USE_REGISTRY_TIMEZONE
 static const char tzRegPath[] = "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones";
 static const char currTzRegPath[] = "SYSTEM\\CurrentControlSet\\Control\\TimeZoneInformation";
+#endif
 
 enum {
     MIN_YEAR = -292275056,
@@ -123,6 +128,7 @@ static bool equalTzi(const TIME_ZONE_INFORMATION &tzi1, const TIME_ZONE_INFORMAT
            && wcscmp(tzi1.DaylightName, tzi2.DaylightName) == 0);
 }
 
+#ifdef QT_USE_REGISTRY_TIMEZONE
 static bool openRegistryKey(const QString &keyPath, HKEY *key)
 {
     return (RegOpenKeyEx(HKEY_LOCAL_MACHINE, (const wchar_t*)keyPath.utf16(), 0, KEY_READ, key)
@@ -197,9 +203,61 @@ static TIME_ZONE_INFORMATION getRegistryTzi(const QByteArray &windowsId, bool *o
 
     return tzi;
 }
+#else // QT_USE_REGISTRY_TIMEZONE
+struct QWinDynamicTimeZone
+{
+    QString standardName;
+    QString daylightName;
+    QString timezoneName;
+    qint32 bias;
+    bool daylightTime;
+};
+
+typedef QHash<QByteArray, QWinDynamicTimeZone> QWinRTTimeZoneHash;
+
+Q_GLOBAL_STATIC(QWinRTTimeZoneHash, gTimeZones)
+
+static void enumerateTimeZones()
+{
+    DYNAMIC_TIME_ZONE_INFORMATION dtzInfo;
+    quint32 index = 0;
+    QString prevTimeZoneKeyName;
+    while (SUCCEEDED(EnumDynamicTimeZoneInformation(index++, &dtzInfo))) {
+        QWinDynamicTimeZone item;
+        item.timezoneName = QString::fromWCharArray(dtzInfo.TimeZoneKeyName);
+        // As soon as key name repeats, break. Some systems continue to always
+        // return the last item independent of index being out of range
+        if (item.timezoneName == prevTimeZoneKeyName)
+            break;
+        item.standardName = QString::fromWCharArray(dtzInfo.StandardName);
+        item.daylightName = QString::fromWCharArray(dtzInfo.DaylightName);
+        item.daylightTime = !dtzInfo.DynamicDaylightTimeDisabled;
+        item.bias = dtzInfo.Bias;
+        gTimeZones->insert(item.timezoneName.toUtf8(), item);
+        prevTimeZoneKeyName = item.timezoneName;
+    }
+}
+
+static DYNAMIC_TIME_ZONE_INFORMATION dynamicInfoForId(const QByteArray &windowsId)
+{
+    DYNAMIC_TIME_ZONE_INFORMATION dtzInfo;
+    quint32 index = 0;
+    QString prevTimeZoneKeyName;
+    while (SUCCEEDED(EnumDynamicTimeZoneInformation(index++, &dtzInfo))) {
+        const QString timeZoneName = QString::fromWCharArray(dtzInfo.TimeZoneKeyName);
+        if (timeZoneName == QLatin1String(windowsId))
+            break;
+        if (timeZoneName == prevTimeZoneKeyName)
+            break;
+        prevTimeZoneKeyName = timeZoneName;
+    }
+    return dtzInfo;
+}
+#endif // QT_USE_REGISTRY_TIMEZONE
 
 static QList<QByteArray> availableWindowsIds()
 {
+#ifdef QT_USE_REGISTRY_TIMEZONE
     // TODO Consider caching results in a global static, very unlikely to change.
     QList<QByteArray> list;
     HKEY key = NULL;
@@ -217,10 +275,16 @@ static QList<QByteArray> availableWindowsIds()
         RegCloseKey(key);
     }
     return list;
+#else // QT_USE_REGISTRY_TIMEZONE
+    if (gTimeZones->isEmpty())
+        enumerateTimeZones();
+    return gTimeZones->keys();
+#endif // QT_USE_REGISTRY_TIMEZONE
 }
 
 static QByteArray windowsSystemZoneId()
 {
+#ifdef QT_USE_REGISTRY_TIMEZONE
     // On Vista and later is held in the value TimeZoneKeyName in key currTzRegPath
     QString id;
     HKEY key = NULL;
@@ -241,6 +305,11 @@ static QByteArray windowsSystemZoneId()
         if (equalTzi(getRegistryTzi(winId, &ok), sysTzi))
             return winId;
     }
+#else // QT_USE_REGISTRY_TIMEZONE
+    DYNAMIC_TIME_ZONE_INFORMATION dtzi;
+    if (SUCCEEDED(GetDynamicTimeZoneInformation(&dtzi)))
+        return QString::fromWCharArray(dtzi.TimeZoneKeyName).toLocal8Bit();
+#endif // QT_USE_REGISTRY_TIMEZONE
 
     // If we can't determine the current ID use UTC
     return QTimeZonePrivate::utcQByteArray();
@@ -361,6 +430,7 @@ void QWinTimeZonePrivate::init(const QByteArray &ianaId)
     }
 
     if (!m_windowsId.isEmpty()) {
+#ifdef QT_USE_REGISTRY_TIMEZONE
         // Open the base TZI for the time zone
         HKEY baseKey = NULL;
         const QString baseKeyPath = QString::fromUtf8(tzRegPath) + QLatin1Char('\\')
@@ -397,6 +467,34 @@ void QWinTimeZonePrivate::init(const QByteArray &ianaId)
             }
             RegCloseKey(baseKey);
         }
+#else // QT_USE_REGISTRY_TIMEZONE
+        if (gTimeZones->isEmpty())
+            enumerateTimeZones();
+        QWinRTTimeZoneHash::const_iterator it = gTimeZones->find(m_windowsId);
+        if (it != gTimeZones->constEnd()) {
+            m_displayName = it->timezoneName;
+            m_standardName = it->standardName;
+            m_daylightName = it->daylightName;
+            DWORD firstYear = 0;
+            DWORD lastYear = 0;
+            DYNAMIC_TIME_ZONE_INFORMATION dtzi = dynamicInfoForId(m_windowsId);
+            GetDynamicTimeZoneInformationEffectiveYears(&dtzi, &firstYear, &lastYear);
+            // If there is no dynamic information, you can still query for
+            // year 0, which helps simplifying following part
+            for (DWORD year = firstYear; year <= lastYear; ++year) {
+                TIME_ZONE_INFORMATION tzi;
+                if (!GetTimeZoneInformationForYear(year, &dtzi, &tzi))
+                    continue;
+                QWinTransitionRule rule;
+                rule.standardTimeBias = tzi.Bias + tzi.StandardBias;
+                rule.daylightTimeBias = tzi.Bias + tzi.DaylightBias - rule.standardTimeBias;
+                rule.standardTimeRule = tzi.StandardDate;
+                rule.daylightTimeRule = tzi.DaylightDate;
+                rule.startYear = year;
+                m_tranRules.append(rule);
+            }
+        }
+#endif // QT_USE_REGISTRY_TIMEZONE
     }
 
     // If there are no rules then we failed to find a windowsId or any tzi info
diff --git a/src/corelib/tools/tools.pri b/src/corelib/tools/tools.pri
index ed07f70e87..ed6afe70ce 100644
--- a/src/corelib/tools/tools.pri
+++ b/src/corelib/tools/tools.pri
@@ -147,9 +147,11 @@ else:unix {
     SOURCES += tools/qelapsedtimer_unix.cpp tools/qlocale_unix.cpp tools/qtimezoneprivate_tz.cpp
 }
 else:win32 {
-    SOURCES += tools/qelapsedtimer_win.cpp tools/qlocale_win.cpp
-    !winrt: SOURCES += tools/qtimezoneprivate_win.cpp
+    SOURCES += tools/qelapsedtimer_win.cpp \
+               tools/qlocale_win.cpp \
+               tools/qtimezoneprivate_win.cpp
     winphone: LIBS_PRIVATE += -lWindowsPhoneGlobalizationUtil
+    winrt-*-msvc2013: LIBS += advapi32.lib
 } else:integrity:SOURCES += tools/qelapsedtimer_unix.cpp tools/qlocale_unix.cpp
 else:SOURCES += tools/qelapsedtimer_generic.cpp