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Fix some out-of-range issues with time-zone support

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The MS-Windows back-end neglected to check for overflow when mapping
date and time to milliseconds from the epoch. Add the checks for that
and take care not to return qint64-min as a transition time - that's
the invalidMSecs() value used as a special marker.

QTimeZonePrivate::dataForLocalTime() neglected to handle the case of
the backend being unable to answer offsetFromUtc() for one of the
times requested, which the MS backend might.

Change-Id: I6d7ee2cbf9aaf6678abb24a20e18b5cdac7f5a23
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Edward Welbourne 2021-10-12 11:16:57 +02:00
parent 71e490f0ba
commit 2b26dea51b
2 changed files with 24 additions and 12 deletions
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7
src/corelib/time/qtimezoneprivate.cpp
View File

@ -395,9 +395,12 @@ QTimeZonePrivate::Data QTimeZonePrivate::dataForLocalTime(qint64 forLocalMSecs,
int early = offsetFromUtc(recent);
int late = offsetFromUtc(imminent);
if (early == late) { // > 99% of the time
if (sub_overflow(forLocalMSecs, early * qint64(1000), &utcEpochMSecs))
if (early == late // > 99% of the time
|| late == invalidSeconds()) {
if (early == invalidSeconds()
|| sub_overflow(forLocalMSecs, early * qint64(1000), &utcEpochMSecs)) {
return invalidData(); // Outside representable range
}
} else {
// Close to a DST transition: early > late is near a fall-back,
// early < late is near a spring-forward.

29
src/corelib/time/qtimezoneprivate_win.cpp
View File

@ -1,5 +1,6 @@
/****************************************************************************
**
** Copyright (C) 2021 The Qt Company Ltd.
** Copyright (C) 2013 John Layt <jlayt@kde.org>
** Contact: https://www.qt.io/licensing/
**
@ -41,8 +42,8 @@
#include "qtimezoneprivate_p.h"
#include "qdatetime.h"
#include "qdebug.h"
#include <private/qnumeric_p.h>
#include <algorithm>
@ -95,9 +96,9 @@ namespace {
QDate msecsToDate(qint64 msecs)
{
qint64 jd = JULIAN_DAY_FOR_EPOCH;
if (qAbs(msecs) >= MSECS_PER_DAY) {
jd += (msecs / MSECS_PER_DAY);
// Corner case: don't use qAbs() because msecs may be numeric_limits<qint64>::min()
if (msecs >= MSECS_PER_DAY || msecs <= -MSECS_PER_DAY) {
jd += msecs / MSECS_PER_DAY;
msecs %= MSECS_PER_DAY;
}
@ -275,11 +276,12 @@ QDate calculateTransitionLocalDate(const SYSTEMTIME &rule, int year)
return date;
}
// Converts a date/time value into msecs
inline qint64 timeToMSecs(QDate date, QTime time)
// Converts a date/time value into msecs, returns true on overflow:
inline bool timeToMSecs(QDate date, QTime time, qint64 *msecs)
{
return ((date.toJulianDay() - JULIAN_DAY_FOR_EPOCH) * MSECS_PER_DAY)
+ time.msecsSinceStartOfDay();
qint64 dayms = 0;
return mul_overflow(date.toJulianDay() - JULIAN_DAY_FOR_EPOCH, qint64(MSECS_PER_DAY), &dayms)
|| add_overflow(dayms, qint64(time.msecsSinceStartOfDay()), msecs);
}
qint64 calculateTransitionForYear(const SYSTEMTIME &rule, int year, int bias)
@ -289,8 +291,15 @@ qint64 calculateTransitionForYear(const SYSTEMTIME &rule, int year, int bias)
Q_ASSERT(year);
const QDate date = calculateTransitionLocalDate(rule, year);
const QTime time = QTime(rule.wHour, rule.wMinute, rule.wSecond);
if (date.isValid() && time.isValid())
return timeToMSecs(date, time) + bias * 60000;
qint64 msecs = 0;
using Bound = std::numeric_limits<qint64>;
if (date.isValid() && time.isValid() && !timeToMSecs(date, time, &msecs)) {
// If bias pushes us outside representable range, clip to range - and
// exclude min() from range as it's invalidMSecs():
return bias && add_overflow(msecs, qint64(bias) * 60000, &msecs)
? (bias < 0 ? Bound::min() + 1 : Bound::max())
: (msecs == Bound::min() ? msecs + 1 : msecs);
}
return QTimeZonePrivate::invalidMSecs();
}