diff -Naur qt-x11-free-3.3.8b-orig/src/codecs/qbig5codec.cpp qt-x11-free-3.3.8b/src/codecs/qbig5codec.cpp
--- qt-x11-free-3.3.8b-orig/src/codecs/qbig5codec.cpp	2008-01-15 22:09:13.000000000 +0300
+++ qt-x11-free-3.3.8b/src/codecs/qbig5codec.cpp	2008-08-17 09:36:19.000000000 +0400
@@ -556,6 +556,11 @@
     {
 	//qDebug("QBig5Decoder::toUnicode(const char* chars = \"%s\", int len = %d)", chars, len);
 	QString result;
+	if (!chars) return QString::null;
+	if (chars && (chars[0]=='\0' || len==0)) {
+	    result.setLength(0);
+	    return result;
+	}
 	for (int i=0; i<len; i++) {
 	    uchar ch = chars[i];
 	    switch (nbuf) {
@@ -641,6 +646,11 @@
 {
     //qDebug("QBig5Codec::toUnicode(const char* chars \"%s\", int len = %d)", chars, len);
     QString result;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        result.setLength(0);
+	return result;
+    }
     for (int i=0; i<len; i++) {
 	uchar ch = chars[i];
 	if ( IsLatin(ch) ) {
@@ -842,6 +852,11 @@
     {
 	//qDebug("QBig5hkscsDecoder::toUnicode(const char* chars = \"%s\", int len = %d)", chars, len);
 	QString result;
+	if (!chars) return QString::null;
+	if (chars && (chars[0]=='\0' || len==0)) {
+	    result.setLength(0);
+	    return result;
+	}
 	for (int i=0; i<len; i++) {
 	    uchar ch = chars[i];
 	    switch (nbuf) {
@@ -924,6 +939,11 @@
 {
     //qDebug("QBig5hkscsCodec::toUnicode(const char* chars = \"%s\", int len = %d)", chars, len);
     QString result;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        result.setLength(0);
+        return result;
+    }
     for (int i=0; i<len; i++) {
 	uchar ch = chars[i];
 	if ( IsLatin(ch) ) {
diff -Naur qt-x11-free-3.3.8b-orig/src/codecs/qeucjpcodec.cpp qt-x11-free-3.3.8b/src/codecs/qeucjpcodec.cpp
--- qt-x11-free-3.3.8b-orig/src/codecs/qeucjpcodec.cpp	2008-01-15 22:09:13.000000000 +0300
+++ qt-x11-free-3.3.8b/src/codecs/qeucjpcodec.cpp	2008-08-17 09:36:19.000000000 +0400
@@ -216,6 +216,11 @@
 QString QEucJpCodec::toUnicode(const char* chars, int len) const
 {
     QString result;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        result.setLength(0);
+        return result;
+    }
     for (int i=0; i<len; i++) {
 	uchar ch = chars[i];
 	if ( ch < 0x80 ) {
@@ -407,6 +412,11 @@
     QString toUnicode(const char* chars, int len)
     {
 	QString result;
+	if (!chars) return QString::null;
+	if (chars && (chars[0]=='\0' || len==0)) {
+	    result.setLength(0);
+	    return result;
+	}
 	for (int i=0; i<len; i++) {
 	    uchar ch = chars[i];
 	    switch (nbuf) {
diff -Naur qt-x11-free-3.3.8b-orig/src/codecs/qeuckrcodec.cpp qt-x11-free-3.3.8b/src/codecs/qeuckrcodec.cpp
--- qt-x11-free-3.3.8b-orig/src/codecs/qeuckrcodec.cpp	2008-01-15 22:09:13.000000000 +0300
+++ qt-x11-free-3.3.8b/src/codecs/qeuckrcodec.cpp	2008-08-17 09:36:19.000000000 +0400
@@ -158,6 +158,11 @@
 QString QEucKrCodec::toUnicode(const char* chars, int len) const
 {
     QString result;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        result.setLength(0);
+        return result;
+    }
     for (int i=0; i<len; i++) {
 	uchar ch = chars[i];
 	if (ch == 0)
@@ -289,6 +294,11 @@
     QString toUnicode(const char* chars, int len)
     {
 	QString result;
+	if (!chars) return QString::null;
+	if (chars && (chars[0]=='\0' || len==0)) {
+	    result.setLength(0);
+	    return result;
+	}
 	for (int i=0; i<len; i++) {
 	    uchar ch = chars[i];
 	    if (ch == 0)
diff -Naur qt-x11-free-3.3.8b-orig/src/codecs/qgb18030codec.cpp qt-x11-free-3.3.8b/src/codecs/qgb18030codec.cpp
--- qt-x11-free-3.3.8b-orig/src/codecs/qgb18030codec.cpp	2008-01-15 22:09:13.000000000 +0300
+++ qt-x11-free-3.3.8b/src/codecs/qgb18030codec.cpp	2008-08-17 09:36:19.000000000 +0400
@@ -229,6 +229,11 @@
 QString QGb18030Codec::toUnicode(const char* chars, int len) const
 {
     QString result;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        result.setLength(0);
+        return result;
+    }
     int clen;
 
     //qDebug("QGb18030Codec::toUnicode(const char* chars, int len = %d)", len);
@@ -351,6 +356,11 @@
     QString toUnicode(const char* chars, int len)
     {
 	QString result;
+	if (!chars) return QString::null;
+	if (chars && (chars[0]=='\0' || len==0)) {
+	    result.setLength(0);
+	    return result;
+	}
 	//qDebug("QGb18030Decoder::toUnicode(const char* chars, int len = %d)", len);
 	for (int i=0; i<len; i++) {
 	    uchar ch = chars[i];
@@ -525,6 +535,11 @@
     QString toUnicode(const char* chars, int len)
     {
 	QString result;
+	if (!chars) return QString::null;
+	if (chars && (chars[0]=='\0' || len==0)) {
+	    result.setLength(0);
+	    return result;
+	}
 
 	//qDebug("QGbkDecoder::toUnicode(const char* chars = \"%s\", int len = %d)", chars, len);
 	for (int i=0; i<len; i++) {
@@ -608,6 +623,11 @@
 QString QGbkCodec::toUnicode(const char* chars, int len) const
 {
     QString result;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        result.setLength(0);
+	return result;
+    }
     int clen;
 
     //qDebug("QGbkCodec::toUnicode(const char* chars, int len = %d)", len);
@@ -725,6 +745,11 @@
     QString toUnicode(const char* chars, int len)
     {
 	QString result;
+	if (!chars) return QString::null;
+	if (chars && (chars[0]=='\0' || len==0)) {
+	    result.setLength(0);
+	    return result;
+	}
 	//qDebug("QGb2312Decoder::toUnicode(const char* chars, int len = %d)", len);
 	for (int i=0; i<len; i++) {
 	    uchar ch = chars[i];
@@ -808,6 +833,11 @@
 QString QGb2312Codec::toUnicode(const char* chars, int len) const
 {
     QString result;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        result.setLength(0);
+        return result;
+    }
     int clen;
 
     //qDebug("QGb2312Codec::toUnicode(const char* chars, int len = %d)", len);
diff -Naur qt-x11-free-3.3.8b-orig/src/codecs/qjiscodec.cpp qt-x11-free-3.3.8b/src/codecs/qjiscodec.cpp
--- qt-x11-free-3.3.8b-orig/src/codecs/qjiscodec.cpp	2008-01-15 22:09:13.000000000 +0300
+++ qt-x11-free-3.3.8b/src/codecs/qjiscodec.cpp	2008-08-17 09:36:19.000000000 +0400
@@ -264,6 +264,11 @@
 QString QJisCodec::toUnicode(const char* chars, int len) const
 {
     QString result;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        result.setLength(0);
+	return result;
+    }
     Iso2022State state = Ascii, prev = Ascii;
     for (int i=0; i<len; i++) {
 	uchar ch = chars[i];
@@ -565,6 +570,11 @@
     QString toUnicode(const char* chars, int len)
     {
 	QString result;
+	if (!chars) return QString::null;
+	if (chars && (chars[0]=='\0' || len==0)) {
+	    result.setLength(0);
+	    return result;
+	}
 	for (int i=0; i<len; i++) {
 	    uchar ch = chars[i];
 	    if (esc) {
diff -Naur qt-x11-free-3.3.8b-orig/src/codecs/qrtlcodec.cpp qt-x11-free-3.3.8b/src/codecs/qrtlcodec.cpp
--- qt-x11-free-3.3.8b-orig/src/codecs/qrtlcodec.cpp	2008-01-15 22:09:13.000000000 +0300
+++ qt-x11-free-3.3.8b/src/codecs/qrtlcodec.cpp	2008-08-17 09:36:19.000000000 +0400
@@ -508,6 +508,11 @@
 QString QHebrewCodec::toUnicode(const char* chars, int len ) const
 {
     QString r;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        r.setLength(0);
+	return r;
+    }
     const unsigned char * c = (const unsigned char *)chars;
     QChar::Direction basicDir = QChar::DirON; // neutral, we don't know
 
diff -Naur qt-x11-free-3.3.8b-orig/src/codecs/qsjiscodec.cpp qt-x11-free-3.3.8b/src/codecs/qsjiscodec.cpp
--- qt-x11-free-3.3.8b-orig/src/codecs/qsjiscodec.cpp	2008-01-15 22:09:13.000000000 +0300
+++ qt-x11-free-3.3.8b/src/codecs/qsjiscodec.cpp	2008-08-17 09:40:45.000000000 +0400
@@ -191,6 +191,11 @@
 {
     uint u;
     QString result;
+    if (!chars) return QString::null;
+    if (chars && (chars[0]=='\0' || len==0)) {
+        result.setLength(0);
+        return result;
+    }
     for (int i=0; i<len; i++) {
 	uchar ch = chars[i];
 	if ( ch < 0x80 || IsKana(ch) ) {
@@ -328,7 +333,12 @@
     QString toUnicode(const char* chars, int len)
     {
 	QString result;
-    uint u= 0;
+	if (!chars) return QString::null;
+	if (chars && (chars[0]=='\0' || len==0)) {
+	    result.setLength(0);
+	    return result;
+	}
+	uint u= 0;
 	for (int i=0; i<len; i++) {
 	    uchar ch = chars[i];
 	    switch (nbuf) {
diff -Naur qt-x11-free-3.3.8b-orig/src/codecs/qtextcodec.cpp qt-x11-free-3.3.8b/src/codecs/qtextcodec.cpp
--- qt-x11-free-3.3.8b-orig/src/codecs/qtextcodec.cpp	2008-01-15 22:09:13.000000000 +0300
+++ qt-x11-free-3.3.8b/src/codecs/qtextcodec.cpp	2008-08-17 09:36:19.000000000 +0400
@@ -469,19 +469,19 @@
 // returns a string containing the letters and numbers from input,
 // with a space separating run of a character class. e.g. "iso8859-1"
 // becomes "iso 8859 1"
-static QString lettersAndNumbers( const char * input )
+static QCString lettersAndNumbers( const char * input )
 {
-    QString result;
+    QCString result;
     QChar c;
 
     while( input && *input ) {
-	c = *input;
+	c = QChar( *input, 0 );
  	if ( c.isLetter() || c.isNumber() )
- 	    result += c.lower();
+ 	    result += c.lower().cell();
 	if ( input[1] ) {
 	    // add space at character class transition, except
 	    // transition from upper-case to lower-case letter
-	    QChar n( input[1] );
+	    QChar n( input[1], 0 );
 	    if ( c.isLetter() && n.isLetter() ) {
 		if ( c == c.lower() && n == n.upper() )
 		    result += ' ';
@@ -508,8 +508,8 @@
 
     // if the letters and numbers are the same, we have an "almost"
     // perfect match.
-    QString h( lettersAndNumbers( hint ) );
-    QString n( lettersAndNumbers( name ) );
+    QCString h( lettersAndNumbers( hint ) );
+    QCString n( lettersAndNumbers( name ) );
     if ( h == n )
 	return qstrlen( hint )-1;
 
@@ -593,6 +593,13 @@
 
 QString QWindowsLocalCodec::toUnicode(const char* chars, int len) const
 {
+    if ( !chars ) return QString::null;
+    if ( chars && (chars[0]=='\0' || len==0) ) {
+        QString blank;
+        blank.setLength(0);
+        return blank;
+    }
+
     if ( len == 1 && chars ) {          // Optimization; avoids allocation
 	char c[2];
 	c[0] = *chars;
@@ -1000,8 +1007,13 @@
 */
 QString QTextCodec::toUnicode(const char* chars, int len) const
 {
-    if ( chars == 0 )
-	return QString::null;
+    if ( !chars ) return QString::null;
+    if ( chars && (chars[0]=='\0' || len==0) ) {
+        QString blank;
+        blank.setLength(0);
+        return blank;
+    }
+
     QTextDecoder* i = makeDecoder();
     QString result = i->toUnicode(chars,len);
     delete i;
@@ -1477,6 +1489,13 @@
 
     QString toUnicode(const char* chars, int len) const
     {
+        if ( !chars ) return QString::null;
+        if ( chars && (chars[0]=='\0' || len==0) ) {
+            QString blank;
+            blank.setLength(0);
+            return blank;
+        }
+
 	const uchar* uchars = (const uchar*)chars;
 	QString result;
 	QMultiByteUnicodeTable* multiByte=to_unicode_multiByte;
@@ -1549,6 +1568,13 @@
 
 QString QTextCodecFromIODDecoder::toUnicode(const char* chars, int len)
 {
+    if ( !chars ) return QString::null;
+    if ( chars && (chars[0]=='\0' || len==0) ) {
+        QString blank;
+        blank.setLength(0);
+        return blank;
+    }
+
     const uchar* uchars = (const uchar*)chars;
     QString result;
     while (len--) {
@@ -2319,13 +2345,17 @@
 
 QString QSimpleTextCodec::toUnicode(const char* chars, int len) const
 {
-    if ( len <= 0 || chars == 0 )
-	return QString::null;
+    if ( !chars ) return QString::null;
+    if ( chars && (chars[0]=='\0' || len==0) ) {
+        QString blank;
+        blank.setLength(0);
+        return blank;
+    }
 
     const unsigned char * c = (const unsigned char *)chars;
     int i;
 
-    for ( i = 0; i < len; i++ )
+    for ( i = 0; i < len || len < 0; i++ )
 	if ( c[i] == '\0' ) {
 	    len = i;
 	    break;
@@ -2515,10 +2545,29 @@
 
 QString QLatin1Codec::toUnicode(const char* chars, int len) const
 {
-    if ( chars == 0 )
-	return QString::null;
+    if ( !chars ) return QString::null;
+    if ( chars && (chars[0]=='\0' || len==0) ) {
+        QString blank;
+        blank.setLength(0);
+        return blank;
+    }
+
+    QString r;
+ 
+    const unsigned char * c = (const unsigned char *)chars;
+    int i;
+
+    for ( i = 0; i < len; i++ ) 
+        if ( c[i] == '\0' ) len = i;
 
-    return QString::fromLatin1(chars, len);
+    if( len > 0 ) {
+        r.setUnicode(0, len);
+        QChar* uc = (QChar*)r.unicode(); // const_cast
+
+        for ( i = 0; i < len; i++ )
+            uc[i] = QChar( c[i], 0 );
+    }
+    return r;
 }
 
 
diff -Naur qt-x11-free-3.3.8b-orig/src/codecs/qutfcodec.cpp qt-x11-free-3.3.8b/src/codecs/qutfcodec.cpp
--- qt-x11-free-3.3.8d/src/codecs/qutfcodec.cpp~	2011-11-16 18:51:21.000000000 +0400
+++ qt-x11-free-3.3.8d/src/codecs/qutfcodec.cpp	2011-11-16 18:54:06.000000000 +0400
@@ -303,6 +303,16 @@ public:
     QString toUnicode(const char* chars, int len)
     {
 	QString result;
+        if (!chars) return QString::null;
+        if (chars && (chars[0]=='\0' || len==0)) {
+            result.setLength(0);
+            return result;
+        }
+        if (!chars) return QString::null;
+        if (chars && (chars[0]=='\0' || len==0)) {
+            result.setLength(0);
+            return result;
+        }
 	result.setLength( len + 1 ); // worst case
 	QChar *qch = (QChar *)result.unicode();
 	QChar ch;