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Restructure Dynamic TZ query to same form as Registry variant

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Break out the reading of an individual rule to a function and add a
fall-back that tries to get a non-dynamic rule when there's no dynamic
data for the zone.  At the same time, change the first rule, in all
cases to apply for all time (i.e. set its .startYear to MIN_YEAR,
instead of 1970 or the advertised start range): we'll use it when
extrapolating backwards into the past.

Change-Id: Ife548c7c7deebef2427d2838f3e12ed7abb631c1
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Edward Welbourne 2017-10-31 16:08:38 +01:00
parent f0fc28ee30
commit fd7fc981d8
1 changed files with 39 additions and 17 deletions
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56
src/corelib/tools/qtimezoneprivate_win.cpp
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@ -259,6 +259,22 @@ static DYNAMIC_TIME_ZONE_INFORMATION dynamicInfoForId(const QByteArray &windowsI
}
return dtzInfo;
}
static QWinTimeZonePrivate::QWinTransitionRule
readDynamicRule(DYNAMIC_TIME_ZONE_INFORMATION &dtzi, int year, bool *ok)
{
TIME_ZONE_INFORMATION tzi;
QWinTimeZonePrivate::QWinTransitionRule rule;
*ok = GetTimeZoneInformationForYear(year, &dtzi, &tzi);
if (*ok) {
rule.startYear = 0;
rule.standardTimeBias = tzi.Bias + tzi.StandardBias;
rule.daylightTimeBias = tzi.Bias + tzi.DaylightBias - rule.standardTimeBias;
rule.standardTimeRule = tzi.StandardDate;
rule.daylightTimeRule = tzi.DaylightDate;
}
return rule;
}
#endif // QT_USE_REGISTRY_TIMEZONE
static QList<QByteArray> availableWindowsIds()
@ -484,16 +500,17 @@ void QWinTimeZonePrivate::init(const QByteArray &ianaId)
QWinTransitionRule rule = readRegistryRule(dynamicKey,
(LPCWSTR)QString::number(year).utf16(),
&ruleOk);
rule.startYear = year;
if (ruleOk)
if (ruleOk) {
rule.startYear = m_tranRules.isEmpty() ? MIN_YEAR : year;
m_tranRules.append(rule);
}
}
RegCloseKey(dynamicKey);
} else {
// No dynamic data so use the base data
bool ruleOk;
QWinTransitionRule rule = readRegistryRule(baseKey, L"TZI", &ruleOk);
rule.startYear = 1970;
rule.startYear = MIN_YEAR;
if (ruleOk)
m_tranRules.append(rule);
}
@ -510,20 +527,25 @@ void QWinTimeZonePrivate::init(const QByteArray &ianaId)
DWORD firstYear = 0;
DWORD lastYear = 0;
DYNAMIC_TIME_ZONE_INFORMATION dtzi = dynamicInfoForId(m_windowsId);
GetDynamicTimeZoneInformationEffectiveYears(&dtzi, &firstYear, &lastYear);
// If there is no dynamic information, you can still query for
// year 0, which helps simplifying following part
for (DWORD year = firstYear; year <= lastYear; ++year) {
TIME_ZONE_INFORMATION tzi;
if (!GetTimeZoneInformationForYear(year, &dtzi, &tzi))
continue;
QWinTransitionRule rule;
rule.standardTimeBias = tzi.Bias + tzi.StandardBias;
rule.daylightTimeBias = tzi.Bias + tzi.DaylightBias - rule.standardTimeBias;
rule.standardTimeRule = tzi.StandardDate;
rule.daylightTimeRule = tzi.DaylightDate;
rule.startYear = year;
m_tranRules.append(rule);
if (GetDynamicTimeZoneInformationEffectiveYears(&dtzi, &firstYear, &lastYear)
== ERROR_SUCCESS && firstYear < lastYear) {
for (DWORD year = firstYear; year <= lastYear; ++year) {
bool ok = false;
QWinTransitionRule rule = readDynamicRule(dtzi, year, &ok);
if (ok) {
rule.startYear = m_tranRules.isEmpty() ? MIN_YEAR : year;
m_tranRules.append(rule);
}
}
} else {
// At least try to get the non-dynamic data:
dtzi.DynamicDaylightTimeDisabled = false;
bool ok = false;
QWinTransitionRule rule = readDynamicRule(dtzi, 1970, &ok);
if (ok) {
rule.startYear = MIN_YEAR;
m_tranRules.append(rule);
}
}
}
#endif // QT_USE_REGISTRY_TIMEZONE