From 530e0bd469e6859269c2d1a792b8ce819fbff389 Mon Sep 17 00:00:00 2001 From: Edward Welbourne Date: Thu, 18 Feb 2021 18:33:18 +0100 Subject: Use QTimeZone to determine offsets outside the system-function range MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Follow up on some comments saying "TODO Use QTimeZone when available" in converting times, outside the range supported by the system's time_t functions, between local or zone time and UTC. Since this required two formerly static functions in qdatetime.cpp to access QTimeZone's d-ptr, turn those into methods of QTZ's friend QDTPrivate. Change-Id: I27fe03d8eff9f4e98661263b1a1d4d830f4e7459 Reviewed-by: Qt CI Bot Reviewed-by: Mårten Nordheim --- src/corelib/time/qdatetime.cpp | 75 ++++++++++++++++++++++++++++++------------ src/corelib/time/qdatetime_p.h | 7 ++++ 2 files changed, 61 insertions(+), 21 deletions(-) diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp index a3516ddb67..28816ccef6 100644 --- a/src/corelib/time/qdatetime.cpp +++ b/src/corelib/time/qdatetime.cpp @@ -2638,8 +2638,8 @@ static inline bool millisInSystemRange(qint64 millis, qint64 slack = 0) } // Convert an MSecs Since Epoch into Local Time -static bool epochMSecsToLocalTime(qint64 msecs, QDate *localDate, QTime *localTime, - QDateTimePrivate::DaylightStatus *daylightStatus = nullptr) +bool QDateTimePrivate::epochMSecsToLocalTime(qint64 msecs, QDate *localDate, QTime *localTime, + QDateTimePrivate::DaylightStatus *daylightStatus) { if (msecs < 0) { // Docs state any LocalTime before 1970-01-01 will *not* have any Daylight Time applied @@ -2654,9 +2654,23 @@ static bool epochMSecsToLocalTime(qint64 msecs, QDate *localDate, QTime *localTi if (!millisInSystemRange(msecs)) { // Docs state any LocalTime after 2038-01-18 *will* have any DST applied. // When this falls outside the supported range, we need to fake it. - // Use existing method to fake the conversion, but this is deeply flawed as it may - // apply the conversion from the wrong day number, e.g. if rule is last Sunday of month - // TODO Use QTimeZone when available to apply the future rule correctly +#if QT_CONFIG(timezone) + // Use the system time-zone. + const auto sys = QTimeZone::systemTimeZone(); + if (daylightStatus) { + *daylightStatus = sys.d->isDaylightTime(msecs) + ? QDateTimePrivate::DaylightTime + : QDateTimePrivate::StandardTime; + } + + if (add_overflow(msecs, sys.d->offsetFromUtc(msecs) * MSECS_PER_SEC, &msecs)) + return false; + msecsToTime(msecs, localDate, localTime); + return true; +#else // Kludge + // Use existing method to fake the conversion (this is deeply flawed + // as it may apply the conversion from the wrong day number, e.g. if + // rule is last Sunday of month). QDate utcDate; QTime utcTime; msecsToTime(msecs, &utcDate, &utcTime); @@ -2670,6 +2684,7 @@ static bool epochMSecsToLocalTime(qint64 msecs, QDate *localDate, QTime *localTi bool res = qt_localtime(fakeMsecs, localDate, localTime, daylightStatus); *localDate = localDate->addDays(fakeDate.daysTo(utcDate)); return res; +#endif // timezone } // Falls inside time_t supported range so can use localtime @@ -2679,10 +2694,10 @@ static bool epochMSecsToLocalTime(qint64 msecs, QDate *localDate, QTime *localTi // Convert a LocalTime expressed in local msecs encoding and the corresponding // DST status into a UTC epoch msecs. Optionally populate the returned // values from mktime for the adjusted local date and time. -static qint64 localMSecsToEpochMSecs(qint64 localMsecs, - QDateTimePrivate::DaylightStatus *daylightStatus, - QDate *localDate = nullptr, QTime *localTime = nullptr, - QString *abbreviation = nullptr) +qint64 QDateTimePrivate::localMSecsToEpochMSecs(qint64 localMsecs, + QDateTimePrivate::DaylightStatus *daylightStatus, + QDate *localDate, QTime *localTime, + QString *abbreviation) { QDate dt; QTime tm; @@ -2703,15 +2718,15 @@ static qint64 localMSecsToEpochMSecs(qint64 localMsecs, } // Restore dt and tm, after qt_mktime() stomped them: msecsToTime(localMsecs, &dt, &tm); - } else { - // If we don't call mktime then we need to call tzset to set up local zone data: + } else if (localMsecs < MSECS_PER_DAY) { + // Didn't call mktime(), but the pre-epoch code below needs mktime()'s + // implicit tzset() call to have happened. qTzSet(); } if (localMsecs <= MSECS_PER_DAY) { // Would have been caught above if after UTC epoch, so is before. // Docs state any LocalTime before 1970-01-01 will *not* have any DST applied - // Time is clearly before 1970-01-01 so just use standard offset to convert const qint64 utcMsecs = localMsecs + qt_timezone() * MSECS_PER_SEC; if (localDate || localTime) msecsToTime(localMsecs, localDate, localTime); @@ -2723,9 +2738,25 @@ static qint64 localMSecsToEpochMSecs(qint64 localMsecs, } // Otherwise, after the end of the system range. - // Use existing method to fake the conversion, but this is deeply flawed as it may - // apply the conversion from the wrong day number, e.g. if rule is last Sunday of month - // TODO Use QTimeZone when available to apply the future rule correctly +#if QT_CONFIG(timezone) + // Use the system zone: + const auto sys = QTimeZone::systemTimeZone(); + const qint64 utcMsecs = + QDateTimePrivate::zoneMSecsToEpochMSecs(localMsecs, sys, + QDateTimePrivate::UnknownDaylightTime, + localDate, localTime); + if (abbreviation) + *abbreviation = sys.d->abbreviation(utcMsecs); + if (daylightStatus) { + *daylightStatus = sys.d->isDaylightTime(utcMsecs) + ? QDateTimePrivate::DaylightTime + : QDateTimePrivate::StandardTime; + } + return utcMsecs; +#else // Kludge + // Use existing method to fake the conversion (this is deeply flawed as it + // may apply the conversion from the wrong day number, e.g. if rule is last + // Sunday of month). int year, month, day; dt.getDate(&year, &month, &day); // 2037 is not a leap year, so make sure date isn't Feb 29 @@ -2744,6 +2775,7 @@ static qint64 localMSecsToEpochMSecs(qint64 localMsecs, QTime utcTime; msecsToTime(utcMsecs, &utcDate, &utcTime); return timeToMSecs(utcDate.addDays(fakeDiff), utcTime); +#endif } static inline bool specCanBeSmall(Qt::TimeSpec spec) @@ -2874,7 +2906,8 @@ static void refreshZonedDateTime(QDateTimeData &d, Qt::TimeSpec spec) QTime testTime; auto dstStatus = extractDaylightStatus(status); if (spec == Qt::LocalTime) { - epochMSecs = localMSecsToEpochMSecs(msecs, &dstStatus, &testDate, &testTime); + epochMSecs = + QDateTimePrivate::localMSecsToEpochMSecs(msecs, &dstStatus, &testDate, &testTime); #if QT_CONFIG(timezone) // else spec == Qt::TimeZone, so check zone is valid: } else if (d->m_timeZone.isValid()) { @@ -3678,7 +3711,7 @@ QString QDateTime::timeZoneAbbreviation() const case Qt::LocalTime: { QString abbrev; auto status = extractDaylightStatus(getStatus(d)); - localMSecsToEpochMSecs(getMSecs(d), &status, nullptr, nullptr, &abbrev); + QDateTimePrivate::localMSecsToEpochMSecs(getMSecs(d), &status, nullptr, nullptr, &abbrev); return abbrev; } } @@ -3715,7 +3748,7 @@ bool QDateTime::isDaylightTime() const case Qt::LocalTime: { auto status = extractDaylightStatus(getStatus(d)); if (status == QDateTimePrivate::UnknownDaylightTime) - localMSecsToEpochMSecs(getMSecs(d), &status); + QDateTimePrivate::localMSecsToEpochMSecs(getMSecs(d), &status); return (status == QDateTimePrivate::DaylightTime); } } @@ -3858,7 +3891,7 @@ qint64 QDateTime::toMSecsSinceEpoch() const if (!d.isShort()) return d->m_msecs - d->m_offsetFromUtc * MSECS_PER_SEC; // Offset from UTC not recorded: need to recompute. - return localMSecsToEpochMSecs(getMSecs(d), &status); + return QDateTimePrivate::localMSecsToEpochMSecs(getMSecs(d), &status); } case Qt::TimeZone: @@ -3950,7 +3983,7 @@ void QDateTime::setMSecsSinceEpoch(qint64 msecs) QDate dt; QTime tm; QDateTimePrivate::DaylightStatus dstStatus; - epochMSecsToLocalTime(msecs, &dt, &tm, &dstStatus); + QDateTimePrivate::epochMSecsToLocalTime(msecs, &dt, &tm, &dstStatus); setDateTime(d, dt, tm); refreshZonedDateTime(d, spec); // FIXME: we do this again, below msecs = getMSecs(d); @@ -4158,7 +4191,7 @@ static inline void massageAdjustedDateTime(QDateTimeData &d, QDate date, QTime t auto spec = getSpec(d); if (spec == Qt::LocalTime) { QDateTimePrivate::DaylightStatus status = QDateTimePrivate::UnknownDaylightTime; - localMSecsToEpochMSecs(timeToMSecs(date, time), &status, &date, &time); + QDateTimePrivate::localMSecsToEpochMSecs(timeToMSecs(date, time), &status, &date, &time); #if QT_CONFIG(timezone) } else if (spec == Qt::TimeZone && d->m_timeZone.isValid()) { QDateTimePrivate::zoneMSecsToEpochMSecs(timeToMSecs(date, time), diff --git a/src/corelib/time/qdatetime_p.h b/src/corelib/time/qdatetime_p.h index 9dcd896d59..8f9773ba72 100644 --- a/src/corelib/time/qdatetime_p.h +++ b/src/corelib/time/qdatetime_p.h @@ -118,6 +118,13 @@ public: static QDateTime::Data create(QDate toDate, QTime toTime, const QTimeZone & timeZone); #endif // timezone + static bool epochMSecsToLocalTime(qint64 msecs, QDate *localDate, QTime *localTime, + QDateTimePrivate::DaylightStatus *daylightStatus = nullptr); + static qint64 localMSecsToEpochMSecs(qint64 localMsecs, + QDateTimePrivate::DaylightStatus *daylightStatus, + QDate *localDate = nullptr, QTime *localTime = nullptr, + QString *abbreviation = nullptr); + StatusFlags m_status = StatusFlag(Qt::LocalTime << TimeSpecShift); qint64 m_msecs = 0; int m_offsetFromUtc = 0; -- cgit v1.2.3