Workaround for OpenC daylight saving cache issue when using localtime_r.

OpenC incorrectly caches DST information between localtime_r
calls, i.e. if previous call to localtime_r has been called for DST
affected date, also the second call will be affected by DST even
the date is such that DST should not be applied.

The workaround is to call mktime with non-DST affected date before
calling localtime_r. mktime call resets the OpenC internal DST cache
to right value and localtime_r will return correct values.

This commit can be reverted once Open C bug 9525 has been reverted.

AutoTest: Fixes tst_QDateTime::totime_t
Reviewed-by: Aleksandar Sasha Babic

1 files changed, 30 insertions, 2 deletions

diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 1b559cf..1277623 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -54,7 +54,6 @@
 #ifndef Q_WS_WIN
 #include <locale.h>
 #endif
-
 #include <time.h>
 #if defined(Q_OS_WINCE)
 #include "qfunctions_wince.h"
@@ -69,6 +68,31 @@
 #  define QDTPDEBUGN if (false) qDebug
 #endif
 
+#if defined(Q_OS_SYMBIAN)
+    // Workaround for OpenC bug.
+
+    // OpenC incorrectly caches DST information between localtime_r
+    // calls, i.e. if previous call to localtime_r has been called for DST
+    // affected date, also the second call will be affected by DST even
+    // the date is such that DST should not be applied.
+
+    // The workaround is to call mktime with non-DST affected date before
+    // calling localtime_r. mktime call resets the OpenC internal DST cache
+    // to right value and localtime_r will return correct values.
+#define FIX_OPENC_DSTCACHE \
+    tm localTM; \
+    localTM.tm_sec = 0; \
+    localTM.tm_min = 0; \
+    localTM.tm_hour = 12; \
+    localTM.tm_mday = 1; \
+    localTM.tm_mon = 1; \
+    localTM.tm_year = 2002 - 1900; \
+    localTM.tm_isdst = -1; \
+    time_t temp = mktime(&localTM);
+#else
+#define FIX_OPENC_DSTCACHE
+#endif
+
 #if defined(Q_WS_MAC)
 #include <private/qcore_mac_p.h>
 #endif
@@ -1138,6 +1162,7 @@ QDate QDate::currentDate()
     // use the reentrant version of localtime() where available
     tzset();
     tm res;
+    FIX_OPENC_DSTCACHE
     t = localtime_r(&ltime, &res);
 #else
     t = localtime(&ltime);
@@ -1834,12 +1859,13 @@ QTime QTime::currentTime()
     // use the reentrant version of localtime() where available
     tzset();
     tm res;
+    FIX_OPENC_DSTCACHE
     t = localtime_r(&ltime, &res);
 #else
     t = localtime(&ltime);
 #endif
     Q_CHECK_PTR(t);
-    
+
     ct.mds = MSECS_PER_HOUR * t->tm_hour + MSECS_PER_MIN * t->tm_min + 1000 * t->tm_sec
              + tv.tv_usec / 1000;
 #else
@@ -2887,6 +2913,7 @@ QDateTime QDateTime::currentDateTime()
     // use the reentrant version of localtime() where available
     tzset();
     tm res;
+    FIX_OPENC_DSTCACHE
     t = localtime_r(&ltime, &res);
 #else
     t = localtime(&ltime);
@@ -3704,6 +3731,7 @@ static QDateTimePrivate::Spec utcToLocal(QDate &date, QTime &time)
     // use the reentrant version of localtime() where available
     tzset();
     tm res;
+    FIX_OPENC_DSTCACHE
     brokenDown = localtime_r(&secsSince1Jan1970UTC, &res);
 #elif defined(_MSC_VER) && _MSC_VER >= 1400
     tm res;