Bug 331719: Prevent crash if restoration fails and kalarm restarts

If session restoration had nothing to restore, the application exits.
If it is started separately before exit is complete, it crashed
because the calendars and other data had been tidied up/closed, but
not re-opened. This reinitialises necessary data in this circumstance.

kalarmapp.cpp

 /*
  *  kalarmapp.cpp  -  the KAlarm application object
  *  Program:  kalarm
- *  Copyright © 2001-2013 by David Jarvie <djarvie@kde.org>
+ *  Copyright © 2001-2014 by David Jarvie <djarvie@kde.org>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -119,7 +119,7 @@ KAlarmApp::KAlarmApp()
       mLoginAlarmsDone(false),
       mDBusHandler(new DBusHandler()),
       mTrayWindow(0),
-      mAlarmTimer(new QTimer(this)),
+      mAlarmTimer(0),
       mArchivedPurgeDays(-1),      // default to not purging
       mPurgeDaysQueued(-1),
       mKSpeech(0),
@@ -136,8 +136,6 @@ KAlarmApp::KAlarmApp()
 #ifndef NDEBUG
     KAlarm::setTestModeConditions();
 #endif
-    mAlarmTimer->setSingleShot(true);
-    connect(mAlarmTimer, SIGNAL(timeout()), SLOT(checkNextDueAlarm()));
 
     setQuitOnLastWindowClosed(false);
     Preferences::self();    // read KAlarm configuration
@@ -161,11 +159,9 @@ KAlarmApp::KAlarmApp()
     KAEvent::setWorkTime(Preferences::workDays(), Preferences::workDayStart(), Preferences::workDayEnd());
     KAEvent::setHolidays(Preferences::holidays());
     KAEvent::setDefaultFont(Preferences::messageFont());
-    if (AlarmCalendar::initialiseCalendars())
+    if (initialise())   // initialise calendars and alarm timer
     {
-        connect(AlarmCalendar::resources(), SIGNAL(earliestAlarmChanged()), SLOT(checkNextDueAlarm()));
 #ifdef USE_AKONADI
-        connect(AlarmCalendar::resources(), SIGNAL(atLoginEventAdded(KAEvent)), SLOT(atLoginEventAdded(KAEvent)));
         connect(AkonadiModel::instance(), SIGNAL(collectionAdded(Akonadi::Collection)),
                                           SLOT(purgeNewArchivedDefault(Akonadi::Collection)));
         connect(AkonadiModel::instance(), SIGNAL(collectionTreeFetched(Akonadi::Collection::List)),
@@ -183,7 +179,7 @@ KAlarmApp::KAlarmApp()
     mSpeechEnabled = (KServiceTypeTrader::self()->query(QLatin1String("DBUS/Text-to-Speech"), QLatin1String("Name == 'KTTSD'")).count() > 0);
     if (!mSpeechEnabled) { kDebug() << "Speech synthesis disabled (KTTSD not found)"; }
     // Check if KOrganizer is installed
-    QString korg = QLatin1String("korganizer");
+    const QString korg = QLatin1String("korganizer");
     mKOrganizerEnabled = !KStandardDirs::locate("exe", korg).isNull()  ||  !KStandardDirs::findExe(korg).isNull();
     if (!mKOrganizerEnabled) { kDebug() << "KOrganizer options disabled (KOrganizer not found)"; }
 }
@@ -217,6 +213,37 @@ KAlarmApp* KAlarmApp::getInstance()
     return theInstance;
 }
 
+/******************************************************************************
+* (Re)initialise things which are tidied up/closed by quitIf().
+* Reinitialisation can be necessary if session restoration finds nothing to
+* restore and starts quitting the application, but KAlarm then starts up again
+* before the application has exited.
+* Reply = true if calendars were initialised successfully,
+*         false if they were already initialised, or if initialisation failed.
+*/
+bool KAlarmApp::initialise()
+{
+    if (!mAlarmTimer)
+    {
+        mAlarmTimer = new QTimer(this);
+        mAlarmTimer->setSingleShot(true);
+        connect(mAlarmTimer, SIGNAL(timeout()), SLOT(checkNextDueAlarm()));
+    }
+    if (!AlarmCalendar::resources())
+    {
+        kDebug() << "initialising calendars";
+        if (AlarmCalendar::initialiseCalendars())
+        {
+            connect(AlarmCalendar::resources(), SIGNAL(earliestAlarmChanged()), SLOT(checkNextDueAlarm()));
+#ifdef USE_AKONADI
+            connect(AlarmCalendar::resources(), SIGNAL(atLoginEventAdded(KAEvent)), SLOT(atLoginEventAdded(KAEvent)));
+#endif
+            return true;
+        }
+    }
+    return false;
+}
+
 /******************************************************************************
 * Restore the saved session if required.
 */
@@ -629,6 +656,9 @@ bool KAlarmApp::quitIf(int exitCode, bool force)
     }
 
     // This was the last/only running "instance" of the program, so exit completely.
+    // NOTE: Everything which is terminated/deleted here must where applicable
+    //       be initialised in the initialise() method, in case KAlarm is
+    //       started again before application exit completes!
     kDebug() << exitCode << ": quitting";
     MessageWin::stopAudio(true);
     if (mCancelRtcWake)
@@ -2370,9 +2400,10 @@ bool KAlarmApp::initCheck(bool calendarOnly)
 {
     static bool firstTime = true;
     if (firstTime)
-    {
         kDebug() << "first time";
 
+    if (initialise()  ||  firstTime)
+    {
         /* Need to open the display calendar now, since otherwise if display
          * alarms are immediately due, they will often be processed while
          * MessageWin::redisplayAlarms() is executing open() (but before open()
@@ -2382,6 +2413,9 @@ bool KAlarmApp::initCheck(bool calendarOnly)
 
         if (!AlarmCalendar::resources()->open())
             return false;
+    }
+    if (firstTime)
+    {
         setArchivePurgeDays();
 
         // Warn the user if there are no writable active alarm calendars

kalarmapp.h

 /*
  *  kalarmapp.h  -  the KAlarm application object
  *  Program:  kalarm
- *  Copyright © 2001-2013 by David Jarvie <djarvie@kde.org>
+ *  Copyright © 2001-2014 by David Jarvie <djarvie@kde.org>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -197,6 +197,7 @@ class KAlarmApp : public KUniqueApplication
             KAEvent    event;
         };
 
+        bool               initialise();
 #ifdef USE_AKONADI
         bool               initCheck(bool calendarOnly = false, bool waitForCollection = false, Akonadi::Collection::Id = -1);
 #else