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Support POSIX rules as $TZ values 

The TZ environment variable can validly contain a POSIX rule, rather
than an IANA ID, as described here:
http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03

However, if TZ were set to such a value, leading to it being used as
systemTimeZoneId(), it would be passed to QTzTimeZonePrivate::init(),
which is a no-op unless it manages to open a zoneinfo/ file with the
given ianaId as name.  When the environment variable doesn't name a
zoneinfo/ file, we would thus get an invalid time-zone.  We can,
instead, check whether the ianaId looks like a valid POSIX rule and,
if it does, use it as m_posixRule, enabling us to correctly handle
this case.

Tweak parsing of POSIX rules so that a zone using name "UTC" or "GMT"
with an offset other than 0 will be rejected as invalid.  This avoids
parsing a zone name such as "GMT+17" or "UTC+00:01" as a POSIX rule,
where it should be understood as an offset from UTC (and only certain
well-established offsets are supported).

Added two test-cases to tst_QTimeZone::tzTest() for validity of a
POSIX zone value - a simple one constructed during discussion of the
bug, the other taken from an example in:
http://leaf.sourceforge.net/doc/buci-tz3.html

Task-number: QTBUG-75565
Change-Id: Ia5cb1cc56b13b0f6b56258e48be98d04d909e32a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Edward Welbourne 2019-05-03 16:24:51 +02:00
parent b29cc512f8
commit ab2655c559
2 changed files with 22 additions and 1 deletions
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15
src/corelib/tools/qtimezoneprivate_tz.cpp
View File

@ -516,6 +516,10 @@ PosixZone PosixZone::parse(const char *&pos, const char *end)
QString name = QString::fromUtf8(nameBegin, nameEnd - nameBegin);
const int offset = zoneEnd > zoneBegin ? parsePosixOffset(zoneBegin, zoneEnd) : InvalidOffset;
pos = zoneEnd;
// UTC+hh:mm:ss or GMT+hh:mm:ss should be read as offsets from UTC, not as a
// POSIX rule naming a zone as UTC or GMT and specifying a non-zero offset.
if (offset != 0 && (name == QLatin1String("UTC") || name == QLatin1String("GMT")))
return invalid();
return {std::move(name), offset};
}
@ -654,8 +658,17 @@ void QTzTimeZonePrivate::init(const QByteArray &ianaId)
tzif.setFileName(QLatin1String("/usr/share/zoneinfo/") + QString::fromLocal8Bit(ianaId));
if (!tzif.open(QIODevice::ReadOnly)) {
tzif.setFileName(QLatin1String("/usr/lib/zoneinfo/") + QString::fromLocal8Bit(ianaId));
if (!tzif.open(QIODevice::ReadOnly))
if (!tzif.open(QIODevice::ReadOnly)) {
// ianaId may be a POSIX rule, taken from $TZ
const QByteArray zoneInfo = ianaId.split(',').at(0);
const char *begin = zoneInfo.constBegin();
if (PosixZone::parse(begin, zoneInfo.constEnd()).hasValidOffset()
&& (begin == zoneInfo.constEnd()
|| PosixZone::parse(begin, zoneInfo.constEnd()).hasValidOffset())) {
m_id = m_posixRule = ianaId;
}
return;
}
}
}

8
tests/auto/corelib/tools/qtimezone/tst_qtimezone.cpp
View File

@ -915,6 +915,14 @@ void tst_QTimeZone::tzTest()
QTzTimeZonePrivate tzp("Europe/Berlin");
QVERIFY(tzp.isValid());
// Test POSIX-format value for $TZ:
QTzTimeZonePrivate tzposix("MET-1METDST-2,M3.5.0/02:00:00,M10.5.0/03:00:00");
QVERIFY(tzposix.isValid());
QTimeZone tzBrazil("BRT+3"); // parts of Northern Brazil, as a POSIX rule
QVERIFY(tzBrazil.isValid());
QCOMPARE(tzBrazil.offsetFromUtc(QDateTime(QDate(1111, 11, 11).startOfDay())), -10800);
// Test display names by type, either ICU or abbreviation only
QLocale enUS("en_US");
// Only test names in debug mode, names used can vary by ICU version installed