SpeechRecognition: Fix a crash if destroyed while not idle

The crash could be easily reproduced by shutting down the application
during engine initialization, while other initialization tasks were
still in queue.

Change-Id: Ieb688cd84397af10ac41ac37f88cf0a40c334dbe
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>

2 files changed, 15 insertions, 1 deletions

diff --git a/src/asr/qspeechrecognitionmanager.cpp b/src/asr/qspeechrecognitionmanager.cpp
index ccc1309..923112c 100755
--- a/src/asr/qspeechrecognitionmanager.cpp
+++ b/src/asr/qspeechrecognitionmanager.cpp
@@ -50,6 +50,7 @@ QSpeechRecognitionManager::QSpeechRecognitionManager():
     m_session(0),
     m_listening(false),
     m_muted(false),
+    m_exiting(false),
     m_grammar()
 {
 }
@@ -58,6 +59,17 @@ QSpeechRecognitionManager::~QSpeechRecognitionManager()
 {
     foreach (QSpeechRecognitionPluginEngine* engine, m_engines)
         engine->reset();
+    // Clear the containers and set the exiting flag to prevent access to the objects
+    // while they are being destroyed. This could happen if any of the children allow
+    // the events to be processed during destruction, which in turn may cause calls to
+    // QSpeechRecognitionManager API (e.g. createGrammar()).
+    m_engineLoaders.clear();
+    m_engines.clear();
+    m_grammars.clear();
+    m_grammar = GrammarInfo();
+    m_listening = false;
+    m_exiting = true;
+    qDeleteAll(findChildren<QSpeechRecognitionPluginLoader*>());
 }
 
 QSpeechRecognitionManager::AttributeData QSpeechRecognitionManager::getAttribute(const QString &key)
@@ -92,6 +104,8 @@ void QSpeechRecognitionManager::createEngine(const QString &engineName, const QS
 {
     QVariantMap errorParams;
     errorParams.insert(QSpeechRecognition::Engine, engineName);
+    if (m_exiting)
+        return;
     if (!m_engines.contains(engineName)) {
         QSpeechRecognitionPluginEngine *engine = 0;
         QSpeechRecognitionPluginLoader *engineLoader = m_engineLoaders.value(provider, 0);
diff --git a/src/asr/qspeechrecognitionmanager_p.h b/src/asr/qspeechrecognitionmanager_p.h
index e75e07b..79f561d 100755
--- a/src/asr/qspeechrecognitionmanager_p.h
+++ b/src/asr/qspeechrecognitionmanager_p.h
@@ -119,7 +119,7 @@ private:
     int m_session;
     bool m_listening;
     bool m_muted;
-    bool m_statChanged;
+    bool m_exiting;
     GrammarInfo m_grammar;
     QMap<QString, AttributeData> m_attributes;
     QSet<QString> m_updatedAttributes;