QDateTime - Change serialise format

Change the datetime serialisation from using QDateTimePrivate::Spec to
using Qt::TimeSpec. Only public classes and enums are now used to
serialise, making the format safer..

Clean up the code to make each version clearer, this duplicates some
code but is easier to read and support.

Change-Id: I3d8fc05f50f8e8acb9edbb992e5ce06063654b8e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 61 insertions, 28 deletions

diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 4f7da33991..d87a4c1b67 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -4384,7 +4384,18 @@ QDataStream &operator<<(QDataStream &out, const QDateTime &dateTime)
 {
     QDate dt;
     QTime tm;
-    if (out.version() == QDataStream::Qt_5_0) {
+
+    if (out.version() >= QDataStream::Qt_5_2) {
+
+        // In 5.2 we switched to using Qt::TimeSpec and added offset support
+        dateTime.d->getDateTime(&dt, &tm);
+        out << dt << tm << qint8(dateTime.timeSpec());
+        if (dateTime.timeSpec() == Qt::OffsetFromUTC)
+            out << qint32(dateTime.offsetFromUtc());
+
+    } else if (out.version() == QDataStream::Qt_5_0) {
+
+        // In Qt 5.0 we incorrectly serialised all datetimes as UTC.
         // This approach is wrong and should not be used again; it breaks
         // the guarantee that a deserialised local datetime is the same time
         // of day, regardless of which timezone it was serialised in.
@@ -4392,12 +4403,15 @@ QDataStream &operator<<(QDataStream &out, const QDateTime &dateTime)
             dateTime.toUTC().d->getDateTime(&dt, &tm);
         else
             dateTime.d->getDateTime(&dt, &tm);
-        out << dt << tm << (qint8)dateTime.timeSpec();
-    } else {
+        out << dt << tm << qint8(dateTime.timeSpec());
+
+    } else if (out.version() >= QDataStream::Qt_4_0) {
+
+        // From 4.0 to 5.1 (except 5.0) we used QDateTimePrivate::Spec
         dateTime.d->getDateTime(&dt, &tm);
         out << dt << tm;
         if (out.version() >= QDataStream::Qt_4_0) {
-            switch (dateTime.d->m_spec) {
+            switch (dateTime.timeSpec()) {
             case Qt::UTC:
                 out << (qint8)QDateTimePrivate::UTC;
                 break;
@@ -4409,11 +4423,15 @@ QDataStream &operator<<(QDataStream &out, const QDateTime &dateTime)
                 break;
             }
         }
-        if (out.version() >= QDataStream::Qt_5_2
-            && dateTime.d->m_spec == Qt::OffsetFromUTC) {
-            out << qint32(dateTime.offsetFromUtc());
-        }
+
+    } else { // version < QDataStream::Qt_4_0
+
+        // Before 4.0 there was no TimeSpec, only Qt::LocalTime was supported
+        dateTime.d->getDateTime(&dt, &tm);
+        out << dt << tm;
+
     }
+
     return out;
 }
 
@@ -4431,37 +4449,52 @@ QDataStream &operator>>(QDataStream &in, QDateTime &dateTime)
 
     QDate dt;
     QTime tm;
-    in >> dt >> tm;
-
-    if (in.version() == QDataStream::Qt_5_0) {
-        qint8 ts = 0;
-        in >> ts;
-        // We incorrectly stored the datetime as UTC in Qt_5_0.
-        dateTime.setTimeSpec(Qt::UTC);
-        dateTime.d->setDateTime(dt, tm);
-        dateTime = dateTime.toTimeSpec(static_cast<Qt::TimeSpec>(ts));
-    } else {
-        qint8 ts = (qint8)QDateTimePrivate::LocalUnknown;
-        if (in.version() >= QDataStream::Qt_4_0)
-            in >> ts;
-        qint32 offset = 0;
-        if (in.version() >= QDataStream::Qt_5_2 && ts == qint8(QDateTimePrivate::OffsetFromUTC))
+    qint8 ts = 0;
+    Qt::TimeSpec spec = Qt::LocalTime;
+    qint32 offset = 0;
+
+    if (in.version() >= QDataStream::Qt_5_2) {
+
+        // In 5.2 we switched to using Qt::TimeSpec and added offset support
+        in >> dt >> tm >> ts;
+        spec = static_cast<Qt::TimeSpec>(ts);
+        if (spec == Qt::OffsetFromUTC)
             in >> offset;
+        dateTime = QDateTime(dt, tm, spec, offset);
+
+    } else if (in.version() == QDataStream::Qt_5_0) {
+
+        // In Qt 5.0 we incorrectly serialised all datetimes as UTC
+        in >> dt >> tm >> ts;
+        spec = static_cast<Qt::TimeSpec>(ts);
+        dateTime = QDateTime(dt, tm, Qt::UTC);
+        dateTime = dateTime.toTimeSpec(spec);
+
+    } else if (in.version() >= QDataStream::Qt_4_0) {
+
+        // From 4.0 to 5.1 (except 5.0) we used QDateTimePrivate::Spec
+        in >> dt >> tm >> ts;
         switch ((QDateTimePrivate::Spec)ts) {
         case QDateTimePrivate::UTC:
-            dateTime.d->m_spec = Qt::UTC;
+            spec = Qt::UTC;
             break;
         case QDateTimePrivate::OffsetFromUTC:
-            dateTime.d->m_spec = Qt::OffsetFromUTC;
+            spec = Qt::OffsetFromUTC;
             break;
         case QDateTimePrivate::LocalUnknown:
         case QDateTimePrivate::LocalStandard:
         case QDateTimePrivate::LocalDST:
-            dateTime.d->m_spec = Qt::LocalTime;
+            spec = Qt::LocalTime;
             break;
         }
-        dateTime.d->m_offsetFromUtc = offset;
-        dateTime.d->setDateTime(dt, tm);
+        dateTime = QDateTime(dt, tm, spec, offset);
+
+    } else { // version < QDataStream::Qt_4_0
+
+        // Before 4.0 there was no TimeSpec, only Qt::LocalTime was supported
+        in >> dt >> tm;
+        dateTime = QDateTime(dt, tm, spec, offset);
+
     }
 
     return in;