Catch invalid offset returns from QTimeZone backends

If the backends run into an error in computing the offset, they return
INT_MIN; but they are valled via the front-end, which returns zero
when the zone is invalid. So treat INT_MIN returns from the backend
the same as the case of being invalid.

Change-Id: Ic3c4dfe964dbfba4030c770213eca8a63e84736d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

3 files changed, 21 insertions, 12 deletions

diff --git a/src/corelib/time/qtimezone.cpp b/src/corelib/time/qtimezone.cpp
index b9c6d727c8..9ccb0e5f02 100644
--- a/src/corelib/time/qtimezone.cpp
+++ b/src/corelib/time/qtimezone.cpp
@@ -607,9 +607,11 @@ QString QTimeZone::abbreviation(const QDateTime &atDateTime) const
 
 int QTimeZone::offsetFromUtc(const QDateTime &atDateTime) const
 {
-    if (isValid())
-        return d->offsetFromUtc(atDateTime.toMSecsSinceEpoch());
-
+    if (isValid()) {
+        const int offset = d->offsetFromUtc(atDateTime.toMSecsSinceEpoch());
+        if (offset !=  QTimeZonePrivate::invalidSeconds())
+            return offset;
+    }
     return 0;
 }
 
@@ -627,9 +629,11 @@ int QTimeZone::offsetFromUtc(const QDateTime &atDateTime) const
 
 int QTimeZone::standardTimeOffset(const QDateTime &atDateTime) const
 {
-    if (isValid())
-        return d->standardTimeOffset(atDateTime.toMSecsSinceEpoch());
-
+    if (isValid()) {
+        const int offset = d->standardTimeOffset(atDateTime.toMSecsSinceEpoch());
+        if (offset !=  QTimeZonePrivate::invalidSeconds())
+            return offset;
+    }
     return 0;
 }
 
@@ -647,9 +651,11 @@ int QTimeZone::standardTimeOffset(const QDateTime &atDateTime) const
 
 int QTimeZone::daylightTimeOffset(const QDateTime &atDateTime) const
 {
-    if (hasDaylightTime())
-        return d->daylightTimeOffset(atDateTime.toMSecsSinceEpoch());
-
+    if (hasDaylightTime()) {
+        const int offset = d->daylightTimeOffset(atDateTime.toMSecsSinceEpoch());
+        if (offset !=  QTimeZonePrivate::invalidSeconds())
+            return offset;
+    }
     return 0;
 }
 
diff --git a/src/corelib/time/qtimezoneprivate.cpp b/src/corelib/time/qtimezoneprivate.cpp
index be00f658bc..9053d12f01 100644
--- a/src/corelib/time/qtimezoneprivate.cpp
+++ b/src/corelib/time/qtimezoneprivate.cpp
@@ -224,7 +224,10 @@ QString QTimeZonePrivate::abbreviation(qint64 atMSecsSinceEpoch) const
 
 int QTimeZonePrivate::offsetFromUtc(qint64 atMSecsSinceEpoch) const
 {
-    return standardTimeOffset(atMSecsSinceEpoch) + daylightTimeOffset(atMSecsSinceEpoch);
+    const int std = standardTimeOffset(atMSecsSinceEpoch);
+    const int dst = daylightTimeOffset(atMSecsSinceEpoch);
+    const int bad = invalidSeconds();
+    return std == bad || dst == bad ? bad : std + dst;
 }
 
 int QTimeZonePrivate::standardTimeOffset(qint64 atMSecsSinceEpoch) const
diff --git a/tests/auto/corelib/time/qtimezone/tst_qtimezone.cpp b/tests/auto/corelib/time/qtimezone/tst_qtimezone.cpp
index 92676108e0..9c505e5baa 100644
--- a/tests/auto/corelib/time/qtimezone/tst_qtimezone.cpp
+++ b/tests/auto/corelib/time/qtimezone/tst_qtimezone.cpp
@@ -996,10 +996,10 @@ void tst_QTimeZone::malformed()
     const QDateTime now = QDateTime::currentDateTime();
     QTimeZone barf("QUT4tCZ0 , /");
     if (barf.isValid())
-        barf.offsetFromUtc(now);
+        QCOMPARE(barf.offsetFromUtc(now), 0);
     barf = QTimeZone("QtC+09,,MA");
     if (barf.isValid())
-        barf.offsetFromUtc(now);
+        QCOMPARE(barf.offsetFromUtc(now), 0);
 }
 
 void tst_QTimeZone::utcTest()