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Handle invalid system zone case when falling back from time_t functions

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Ammends commit 530e0bd469, in which I
added a QTimeZone-based fall-back for handling of conversions between
local time and UTC when outside the range supported by time_t-based
functions. That replaced prior kludges, when feature timezone is
enabled; however, even with feature timezone, it's possible for the
system zone to be invalid. So retain the old kludges also as fall-back
for when the system zone is invalid, as well as when we have no
timezones to fall back on.

Change-Id: Ie2b8af7f1a87d7b0e39cc5ac0c04b04d574f84b5
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Edward Welbourne 2021-04-28 15:08:50 +02:00
parent 8ec07b4afc
commit ae5d40e674
1 changed files with 30 additions and 26 deletions
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56
src/corelib/time/qdatetime.cpp
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@ -2657,19 +2657,22 @@ bool QDateTimePrivate::epochMSecsToLocalTime(qint64 msecs, QDate *localDate, QTi
#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 (sys.isValid()) {
if (daylightStatus) {
*daylightStatus = sys.d->isDaylightTime(msecs)
? QDateTimePrivate::DaylightTime
: QDateTimePrivate::StandardTime;
}
// NB: cast to qint64 here is important to make sure a matching
// add_overflow is found, GCC 7.5.0 fails without this cast
if (add_overflow(msecs, qint64(sys.d->offsetFromUtc(msecs) * MSECS_PER_SEC), &msecs))
return false;
msecsToTime(msecs, localDate, localTime);
return true;
#else // Kludge
// NB: cast to qint64 here is important to make sure a matching
// add_overflow is found, GCC 7.5.0 fails without this cast
if (add_overflow(msecs, qint64(sys.d->offsetFromUtc(msecs)) * MSECS_PER_SEC, &msecs))
return false;
msecsToTime(msecs, localDate, localTime);
return true;
}
#endif // timezone
// 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).
@ -2686,7 +2689,6 @@ bool QDateTimePrivate::epochMSecsToLocalTime(qint64 msecs, QDate *localDate, QTi
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
@ -2743,19 +2745,22 @@ qint64 QDateTimePrivate::localMSecsToEpochMSecs(qint64 localMsecs,
#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;
if (sys.isValid()) {
const qint64 utcMsecs =
QDateTimePrivate::zoneMSecsToEpochMSecs(localMsecs, sys,
QDateTimePrivate::UnknownDaylightTime,
localDate, localTime);
if (abbreviation && sys.isValid())
*abbreviation = sys.d->abbreviation(utcMsecs);
if (daylightStatus) {
*daylightStatus = sys.isValid() && sys.d->isDaylightTime(utcMsecs)
? QDateTimePrivate::DaylightTime
: QDateTimePrivate::StandardTime;
}
return utcMsecs;
}
return utcMsecs;
#else // Kludge
#endif // timezone
// 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).
@ -2777,7 +2782,6 @@ qint64 QDateTimePrivate::localMSecsToEpochMSecs(qint64 localMsecs,
QTime utcTime;
msecsToTime(utcMsecs, &utcDate, &utcTime);
return timeToMSecs(utcDate.addDays(fakeDiff), utcTime);
#endif
}
static inline bool specCanBeSmall(Qt::TimeSpec spec)