Fix BOM for UTF-32 codec

The BOM was created correctly, but half of the BOM was then overwritten
by the converted data afterwards.
Also made the autotest also do reverse encoding tests where possible.

Task-number: 255095
Reviewed-by: lars

2 files changed, 13 insertions, 4 deletions

diff --git a/src/corelib/codecs/qutfcodec.cpp b/src/corelib/codecs/qutfcodec.cpp
index 1ac592e..d9defe1 100644
--- a/src/corelib/codecs/qutfcodec.cpp
+++ b/src/corelib/codecs/qutfcodec.cpp
@@ -478,7 +478,7 @@ QByteArray QUtf32Codec::convertFromUnicode(const QChar *uc, int len, ConverterSt
             data[2] = 0;
             data[3] = 0;
         }
-        data += 2;
+        data += 4;
     }
     if (endian == BE) {
         for (int i = 0; i < len; ++i) {
diff --git a/tests/auto/qtextcodec/tst_qtextcodec.cpp b/tests/auto/qtextcodec/tst_qtextcodec.cpp
index cf4135b..566b20e 100644
--- a/tests/auto/qtextcodec/tst_qtextcodec.cpp
+++ b/tests/auto/qtextcodec/tst_qtextcodec.cpp
@@ -1537,7 +1537,7 @@ void tst_QTextCodec::utfHeaders_data()
         << QByteArray("\xef\xbb\xbfhello")
         << (QString(QChar(0xfeff)) + QString::fromLatin1("hello"))
         << true;
-    QTest::newRow("utf8 nobom")
+    QTest::newRow("utf8 nobom ignore header")
         << QByteArray("UTF-8")
         << (int)QTextCodec::IgnoreHeader
         << QByteArray("hello")
@@ -1718,14 +1718,23 @@ void tst_QTextCodec::utfHeaders()
 
     QFETCH(bool, toUnicode);
 
+    QLatin1String ignoreReverseTestOn = (QSysInfo::ByteOrder == QSysInfo::BigEndian) ? QLatin1String(" le") : QLatin1String(" be");
+    QString rowName(QTest::currentDataTag());
+
     for (int i = 0; i < encoded.length(); ++i)
         qDebug() << hex << "    " << (uint)(uchar)encoded.at(i);
     if (toUnicode) {
         QString result = codec->toUnicode(encoded.constData(), encoded.length(), &state);
-    for (int i = 0; i < result.length(); ++i)
-        qDebug() << hex << "    " << (uint)result.at(i).unicode();
+        for (int i = 0; i < result.length(); ++i)
+            qDebug() << hex << "    " << (uint)result.at(i).unicode();
         QCOMPARE(result.length(), unicode.length());
         QCOMPARE(result, unicode);
+
+        if (!rowName.endsWith("nobom") && !rowName.contains(ignoreReverseTestOn)) {
+            QTextCodec::ConverterState state2(cFlags);
+            QByteArray reencoded = codec->fromUnicode(unicode.unicode(), unicode.length(), &state2);
+            QCOMPARE(reencoded, encoded);
+        }
     } else {
         QByteArray result = codec->fromUnicode(unicode.unicode(), unicode.length(), &state);
         QCOMPARE(result, encoded);