path: root/dev-qt/qtcore/files/qtcore-5.15.1-timezone-1.patch

From c337f6fae51b987ce7dbed1fd9bea41e6073efbb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andreas=20K=2E=20H=C3=BCttel?= <dilfridge@gentoo.org>
Date: Sat, 10 Oct 2020 19:26:13 +0200
Subject: [PATCH 1/2] Revert "Cache system zone ID when fetched from the
 file-system"

This reverts commit c70ce3d042025c858faffe661f85d2482a2a0d8c.
---
 src/corelib/time/qtimezoneprivate_tz.cpp | 205 +++++++----------------
 1 file changed, 64 insertions(+), 141 deletions(-)

diff --git a/src/corelib/time/qtimezoneprivate_tz.cpp b/src/corelib/time/qtimezoneprivate_tz.cpp
index c5c70b7364..01f9a6cce0 100644
--- a/src/corelib/time/qtimezoneprivate_tz.cpp
+++ b/src/corelib/time/qtimezoneprivate_tz.cpp
@@ -1,6 +1,5 @@
 /****************************************************************************
 **
-** Copyright (C) 2020 The Qt Company Ltd.
 ** Copyright (C) 2019 Crimson AS <info@crimson.no>
 ** Copyright (C) 2013 John Layt <jlayt@kde.org>
 ** Contact: https://www.qt.io/licensing/
@@ -43,19 +42,18 @@
 #include "qtimezoneprivate_p.h"
 #include "private/qlocale_tools_p.h"
 
-#include <QtCore/QDataStream>
-#include <QtCore/QDateTime>
 #include <QtCore/QFile>
-#include <QtCore/QHash>
 #include <QtCore/QMutex>
+#include <QtCore/QHash>
+#include <QtCore/QDataStream>
+#include <QtCore/QDateTime>
 
 #include <qdebug.h>
-#include <qplatformdefs.h>
 
 #include <algorithm>
 #include <errno.h>
 #include <limits.h>
-#ifndef Q_OS_INTEGRITY
+#if !defined(Q_OS_INTEGRITY)
 #include <sys/param.h> // to use MAXSYMLINKS constant
 #endif
 #include <unistd.h>    // to use _SC_SYMLOOP_MAX constant
@@ -1102,146 +1100,28 @@ QTimeZonePrivate::Data QTzTimeZonePrivate::previousTransition(qint64 beforeMSecs
     return last > tranCache().cbegin() ? dataForTzTransition(*--last) : invalidData();
 }
 
-bool QTzTimeZonePrivate::isTimeZoneIdAvailable(const QByteArray &ianaId) const
-{
-    return tzZones->contains(ianaId);
-}
-
-QList<QByteArray> QTzTimeZonePrivate::availableTimeZoneIds() const
-{
-    QList<QByteArray> result = tzZones->keys();
-    std::sort(result.begin(), result.end());
-    return result;
-}
-
-QList<QByteArray> QTzTimeZonePrivate::availableTimeZoneIds(QLocale::Country country) const
+static long getSymloopMax()
 {
-    // TODO AnyCountry
-    QList<QByteArray> result;
-    for (auto it = tzZones->cbegin(), end = tzZones->cend(); it != end; ++it) {
-        if (it.value().country == country)
-            result << it.key();
-    }
-    std::sort(result.begin(), result.end());
-    return result;
-}
-
-// Getting the system zone's ID:
-
-namespace {
-class ZoneNameReader : public QObject
-{
-public:
-    QByteArray name()
-    {
-        /* Assumptions:
-           a) Systems don't change which of localtime and TZ they use without a
-              reboot.
-           b) When they change, they use atomic renames, hence a new device and
-              inode for the new file.
-           c) If we change which *name* is used for a zone, while referencing
-              the same final zoneinfo file, we don't care about the change of
-              name (e.g. if Europe/Oslo and Europe/Berlin are both symlinks to
-              the same CET file, continuing to use the old name, after
-              /etc/localtime changes which of the two it points to, is
-              harmless).
-
-           The alternative would be to use a file-system watcher, but they are a
-           scarce resource.
-         */
-        const StatIdent local = identify("/etc/localtime");
-        const StatIdent tz = identify("/etc/TZ");
-        if (!m_name.isEmpty() && m_last.isValid() && (m_last == local || m_last == tz))
-            return m_name;
-
-        m_name = etcLocalTime();
-        if (!m_name.isEmpty()) {
-            m_last = local;
-            return m_name;
-        }
-
-        m_name = etcTZ();
-        m_last = m_name.isEmpty() ? StatIdent() : tz;
-        return m_name;
-    }
-
-
-private:
-    QByteArray m_name;
-    struct StatIdent
-    {
-        static constexpr unsigned long bad = ~0ul;
-        unsigned long m_dev, m_ino;
-        StatIdent() : m_dev(bad), m_ino(bad) {}
-        StatIdent(const QT_STATBUF &data) : m_dev(data.st_dev), m_ino(data.st_ino) {}
-        bool isValid() { return m_dev != bad || m_ino != bad; }
-        bool operator==(const StatIdent &other)
-        { return other.m_dev == m_dev && other.m_ino == m_ino; }
-    };
-    StatIdent m_last;
-
-    static StatIdent identify(const char *path)
-    {
-        QT_STATBUF data;
-        return QT_STAT(path, &data) == -1 ? StatIdent() : StatIdent(data);
-    }
-
-    static QByteArray etcLocalTime()
-    {
-        // On most distros /etc/localtime is a symlink to a real file so extract
-        // name from the path
-        const QLatin1String zoneinfo("/zoneinfo/");
-        QString path = QStringLiteral("/etc/localtime");
-        long iteration = getSymloopMax();
-        // Symlink may point to another symlink etc. before being under zoneinfo/
-        // We stop on the first path under /zoneinfo/, even if it is itself a
-        // symlink, like America/Montreal pointing to America/Toronto
-        do {
-            path = QFile::symLinkTarget(path);
-            int index = path.indexOf(zoneinfo);
-            if (index >= 0) // Found zoneinfo file; extract zone name from path:
-                return path.midRef(index + zoneinfo.size()).toUtf8();
-        } while (!path.isEmpty() && --iteration > 0);
-
-        return QByteArray();
-    }
-
-    static QByteArray etcTZ()
-    {
-        // Some systems (e.g. uClibc) have a default value for $TZ in /etc/TZ:
-        const QString path = QStringLiteral("/etc/TZ");
-        QFile zone(path);
-        if (zone.open(QIODevice::ReadOnly))
-            return zone.readAll().trimmed();
-
-        return QByteArray();
-    }
-
-    // Any chain of symlinks longer than this is assumed to be a loop:
-    static long getSymloopMax()
-    {
-#ifdef SYMLOOP_MAX
-        // If defined, at runtime it can only be greater than this, so this is a safe bet:
-        return SYMLOOP_MAX;
+#if defined(SYMLOOP_MAX)
+    return SYMLOOP_MAX; // if defined, at runtime it can only be greater than this, so this is a safe bet
 #else
-        errno = 0;
-        long result = sysconf(_SC_SYMLOOP_MAX);
-        if (result >= 0)
-            return result;
-        // result is -1, meaning either error or no limit
-        Q_ASSERT(!errno); // ... but it can't be an error, POSIX mandates _SC_SYMLOOP_MAX
-
-        // therefore we can make up our own limit
-#  ifdef MAXSYMLINKS
-        return MAXSYMLINKS;
+    errno = 0;
+    long result = sysconf(_SC_SYMLOOP_MAX);
+    if (result >= 0)
+        return result;
+    // result is -1, meaning either error or no limit
+    Q_ASSERT(!errno); // ... but it can't be an error, POSIX mandates _SC_SYMLOOP_MAX
+
+    // therefore we can make up our own limit
+#  if defined(MAXSYMLINKS)
+    return MAXSYMLINKS;
 #  else
-        return 8;
+    return 8;
 #  endif
 #endif
-    }
-};
 }
 
+// TODO Could cache the value and monitor the required files for any changes
 QByteArray QTzTimeZonePrivate::systemTimeZoneId() const
 {
     // Check TZ env var first, if not populated try find it
@@ -1256,9 +1136,28 @@ QByteArray QTzTimeZonePrivate::systemTimeZoneId() const
     else if (ianaId.startsWith(':'))
         ianaId = ianaId.mid(1);
 
+    // On most distros /etc/localtime is a symlink to a real file so extract name from the path
+    if (ianaId.isEmpty()) {
+        const QLatin1String zoneinfo("/zoneinfo/");
+        QString path = QFile::symLinkTarget(QStringLiteral("/etc/localtime"));
+        int index = -1;
+        long iteration = getSymloopMax();
+        // Symlink may point to another symlink etc. before being under zoneinfo/
+        // We stop on the first path under /zoneinfo/, even if it is itself a
+        // symlink, like America/Montreal pointing to America/Toronto
+        while (iteration-- > 0 && !path.isEmpty() && (index = path.indexOf(zoneinfo)) < 0)
+            path = QFile::symLinkTarget(path);
+        if (index >= 0) {
+            // /etc/localtime is a symlink to the current TZ file, so extract from path
+            ianaId = path.midRef(index + zoneinfo.size()).toUtf8();
+        }
+    }
+
+    // Some systems (e.g. uClibc) have a default value for $TZ in /etc/TZ:
     if (ianaId.isEmpty()) {
-        thread_local static ZoneNameReader reader;
-        ianaId = reader.name();
+        QFile zone(QStringLiteral("/etc/TZ"));
+        if (zone.open(QIODevice::ReadOnly))
+            ianaId = zone.readAll().trimmed();
     }
 
     // Give up for now and return UTC
@@ -1268,4 +1167,28 @@ QByteArray QTzTimeZonePrivate::systemTimeZoneId() const
     return ianaId;
 }
 
+bool QTzTimeZonePrivate::isTimeZoneIdAvailable(const QByteArray &ianaId) const
+{
+    return tzZones->contains(ianaId);
+}
+
+QList<QByteArray> QTzTimeZonePrivate::availableTimeZoneIds() const
+{
+    QList<QByteArray> result = tzZones->keys();
+    std::sort(result.begin(), result.end());
+    return result;
+}
+
+QList<QByteArray> QTzTimeZonePrivate::availableTimeZoneIds(QLocale::Country country) const
+{
+    // TODO AnyCountry
+    QList<QByteArray> result;
+    for (auto it = tzZones->cbegin(), end = tzZones->cend(); it != end; ++it) {
+        if (it.value().country == country)
+            result << it.key();
+    }
+    std::sort(result.begin(), result.end());
+    return result;
+}
+
 QT_END_NAMESPACE
-- 
2.28.0