Prevent creation of text codecs when the application is shutting down. This resolves issue #142

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>
(cherry picked from commit 7563c4825f)

src/codecs/qtextcodec.cpp

@@ -89,7 +89,7 @@
 #endif
 
 static TQValueList<TQTextCodec*> *all = 0;
-static bool destroying_is_ok; // starts out as 0
+static bool codecs_destroyed = false;
 static TQTextCodec * localeMapper = 0;
 
 class TQTextCodecCleanup {
@@ -118,18 +118,16 @@ static TQTextCodecCleanup qtextcodec_cleanup;
 
 void TQTextCodec::deleteAllCodecs()
 {
+    codecs_destroyed = true;
+
     if ( !all )
 	return;
 
 #ifdef TQT_THREAD_SUPPORT
     TQMutexLocker locker( tqt_global_mutexpool ?
 			  tqt_global_mutexpool->get( &all ) : 0 );
-    if ( !all )
-	return;
 #endif // TQT_THREAD_SUPPORT
 
-    destroying_is_ok = TRUE;
-
     TQValueList<TQTextCodec*> *ball = all;
     all = 0;
     TQValueList<TQTextCodec*>::Iterator it;
@@ -140,26 +138,10 @@ void TQTextCodec::deleteAllCodecs()
     ball->clear();
     delete ball;
 
-    destroying_is_ok = FALSE;
-}
-
-
-static void realSetup();
-
-
-static inline void setup()
-{
-    if ( all ) return;
-
-#ifdef TQT_THREAD_SUPPORT
-    TQMutexLocker locker( tqt_global_mutexpool ?
-			 tqt_global_mutexpool->get( &all ) : 0 );
-    if ( all ) return;
-#endif // TQT_THREAD_SUPPORT
-
-    realSetup();
+    localeMapper = 0;
 }
 
+static void setup();
 
 class TQTextStatelessEncoder: public TQTextEncoder {
     const TQTextCodec* codec;
@@ -428,10 +410,18 @@ TQString TQTextStatelessDecoder::toUnicode(const char* chars, int len)
     terminates.
 */
 TQTextCodec::TQTextCodec()
+{
+    // 'codecs_destroyed' should never be true at this point
+    if (!codecs_destroyed)
     {
 	setup();
+#ifdef TQT_THREAD_SUPPORT
+	TQMutexLocker locker( tqt_global_mutexpool ?
+			      tqt_global_mutexpool->get( &all ) : 0 );
+#endif // TQT_THREAD_SUPPORT
 	all->insert( all->begin(), this );
     }
+}
 
 
 /*!
@@ -442,8 +432,13 @@ TQTextCodec::TQTextCodec()
 */
 TQTextCodec::~TQTextCodec()
 {
-    if ( !destroying_is_ok )
+    if ( !codecs_destroyed )
 	tqWarning("TQTextCodec::~TQTextCodec() called by application");
+
+#ifdef TQT_THREAD_SUPPORT
+    TQMutexLocker locker( tqt_global_mutexpool ?
+			  tqt_global_mutexpool->get( &all ) : 0 );
+#endif // TQT_THREAD_SUPPORT
     if ( all )
 	all->remove( this );
 }
@@ -529,6 +524,11 @@ int TQTextCodec::simpleHeuristicNameMatch(const char* name, const char* hint)
 */
 TQTextCodec* TQTextCodec::codecForIndex(int i)
 {
+    if (codecs_destroyed)
+    {
+	return nullptr;
+    }
+
     setup();
     return (uint)i >= all->count() ? 0 : *all->at(i);
 }
@@ -540,6 +540,11 @@ TQTextCodec* TQTextCodec::codecForIndex(int i)
 */
 TQTextCodec* TQTextCodec::codecForMib(int mib)
 {
+    if (codecs_destroyed)
+    {
+	return nullptr;
+    }
+
     setup();
     TQValueList<TQTextCodec*>::ConstIterator i;
     TQTextCodec* result=0;
@@ -818,10 +823,15 @@ void TQTextCodec::setCodecForLocale(TQTextCodec *c) {
 
 TQTextCodec* TQTextCodec::codecForLocale()
 {
-    if ( localeMapper )
-	return localeMapper;
+    if (codecs_destroyed)
+    {
+	return nullptr;
+    }
 
+    if (!localeMapper)
+    {
 	setup();
+    }
 
     return localeMapper;
 }
@@ -838,6 +848,11 @@ TQTextCodec* TQTextCodec::codecForLocale()
 
 TQTextCodec* TQTextCodec::codecForName( const char* name, int accuracy )
 {
+    if (codecs_destroyed)
+    {
+	return nullptr;
+    }
+
     if ( !name || !*name )
 	return 0;
 
@@ -879,6 +894,11 @@ TQTextCodec* TQTextCodec::codecForName( const char* name, int accuracy )
 */
 TQTextCodec* TQTextCodec::codecForContent(const char* chars, int len)
 {
+    if (codecs_destroyed)
+    {
+	return nullptr;
+    }
+
     setup();
     TQValueList<TQTextCodec*>::ConstIterator i;
     TQTextCodec* result = 0;
@@ -2777,7 +2797,7 @@ static TQTextCodec *checkForCodec(const char *name) {
     return c;
 }
 
-/* the next two functions are implicitely thread safe,
+/* the next function is implicitely thread safe,
    as they are only called by setup() which uses a mutex.
 */
 static void setupLocaleMapper()
@@ -2901,12 +2921,32 @@ static void setupLocaleMapper()
 }
 
 
-static void realSetup()
+static void setup()
 {
 #if defined(QT_CHECK_STATE)
-    if ( destroying_is_ok )
-	tqWarning( "TQTextCodec: creating new codec during codec cleanup!" );
+    if ( codecs_destroyed )
+    {
+	// If codecs have been destroyed, the application is being destroyed.
+	// Do not create new codecs since this could lead to SEGV while trying to
+	// print a message using tqWarning/tqDebug/tqFatal at this stage
+	//
+	// Note: the use of `printf` instead of `tqWarning` is intentional. We should never
+	// get to this line of code. If we do, we are in some strange exception that we
+	// didn't think of. Using `tqWarning` could potentially lead to an infinite loop with
+	// `tqWarning` trying to setup codecs and this method calling `tqWarning` again.
+	// Using `printf` makes sure this never happens, even for exceptions we didn't foresee.
+	printf("TQTextCodec: setup() called when codecs have already been destroyed\n"); fflush(stdout);
+	return;
+    }
 #endif
+
+    if ( all ) return;
+
+#ifdef TQT_THREAD_SUPPORT
+    TQMutexLocker locker( tqt_global_mutexpool ?
+			 tqt_global_mutexpool->get( &all ) : 0 );
+#endif // TQT_THREAD_SUPPORT
+
     all = new TQValueList<TQTextCodec*>;
 
     (void)new TQLatin1Codec;