Avoid races on TZ in environment via tzset() calls

POSIX specifies that tzset() consults environment variable TZ and
modifies some globals; it also specifies mktime(), localtime() and
strftime() to behave as if they called tzset().  Fortunately, we only
call strftime() from a test and only call localtime() when not
threaded.  Provide wrappers for tzset() and mktime() that share the
lock used by our environment-access code, to prevent races on the
environment (and tzset()'s globals) when we call them.

In the process, re-use tst_QDateTime's TimeZoneRollback in its older
test systemTimeZoneChange() and presume that this can now be tested
cross-platform, since TimeZoneRollback is used in another test where
this works.

Fixes: QTBUG-71030
Change-Id: I79f559b8857ea2803e73501008bf0d7158c6731f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 7 insertions, 33 deletions

diff --git a/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp b/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp
index 943805e228..56792f38fb 100644
--- a/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp
+++ b/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp
@@ -37,9 +37,6 @@
 
 #ifdef Q_OS_WIN
 #   include <qt_windows.h>
-#  if defined(Q_OS_WINRT)
-#    define tzset()
-#  endif
 #endif
 
 class tst_QDateTime : public QObject
@@ -145,9 +142,7 @@ private slots:
     void isDaylightTime() const;
     void daylightTransitions() const;
     void timeZones() const;
-#if defined(Q_OS_UNIX)
     void systemTimeZoneChange() const;
-#endif
 
     void invalid() const;
 
@@ -174,7 +169,7 @@ private:
         void reset(const QByteArray &zone)
         {
             qputenv("TZ", zone.constData());
-            tzset();
+            qTzSet();
         }
         ~TimeZoneRollback()
         {
@@ -182,7 +177,7 @@ private:
                 qunsetenv("TZ");
             else
                 qputenv("TZ", prior.constData());
-            tzset();
+            qTzSet();
         }
     };
 };
@@ -3412,33 +3407,10 @@ void tst_QDateTime::timeZones() const
     QCOMPARE(future.offsetFromUtc(), 28800);
 }
 
-#if defined(Q_OS_UNIX)
-// Currently disabled on Windows as adjusting the timezone
-// requires additional privileges that aren't normally
-// enabled for a process. This can be achieved by calling
-// AdjustTokenPrivileges() and then SetTimeZoneInformation(),
-// which will require linking to a different library to access that API.
-static void setTimeZone(const QByteArray &tz)
-{
-    qputenv("TZ", tz);
-    ::tzset();
-
-// following left for future reference, see comment above
-// #if defined(Q_OS_WIN32)
-//     ::_tzset();
-// #endif
-}
-
 void tst_QDateTime::systemTimeZoneChange() const
 {
-    struct ResetTZ {
-        QByteArray original;
-        ResetTZ() : original(qgetenv("TZ")) {}
-        ~ResetTZ() { setTimeZone(original); }
-    } scopedReset;
-
     // Set the timezone to Brisbane time
-    setTimeZone(QByteArray("AEST-10:00"));
+    TimeZoneRollback useZone(QByteArray("AEST-10:00"));
 
     QDateTime localDate = QDateTime(QDate(2012, 6, 1), QTime(2, 15, 30), Qt::LocalTime);
     QDateTime utcDate = QDateTime(QDate(2012, 6, 1), QTime(2, 15, 30), Qt::UTC);
@@ -3451,16 +3423,18 @@ void tst_QDateTime::systemTimeZoneChange() const
     QVERIFY(tzDate.timeZone().isValid());
 
     // Change to Indian time
-    setTimeZone(QByteArray("IST-05:30"));
+    useZone.reset(QByteArray("IST-05:30"));
 
     QCOMPARE(localDate, QDateTime(QDate(2012, 6, 1), QTime(2, 15, 30), Qt::LocalTime));
+#ifdef Q_OS_WINRT
+    QEXPECT_FAIL("", "WinRT gets this wrong, QTBUG-71185", Continue);
+#endif
     QVERIFY(localMsecs != localDate.toMSecsSinceEpoch());
     QCOMPARE(utcDate, QDateTime(QDate(2012, 6, 1), QTime(2, 15, 30), Qt::UTC));
     QCOMPARE(utcDate.toMSecsSinceEpoch(), utcMsecs);
     QCOMPARE(tzDate, QDateTime(QDate(2012, 6, 1), QTime(2, 15, 30), QTimeZone("Australia/Brisbane")));
     QCOMPARE(tzDate.toMSecsSinceEpoch(), tzMsecs);
 }
-#endif
 
 void tst_QDateTime::invalid() const
 {