Added stream version into network cache file format

At the moment, there is no stream information in the cache file. This
can lead to a problem when current stream version differs from version
cache file written with.

As an example, if file written with Qt 5.1.1, QTimeDate in the metadata
stored as 13-bytes value, but Qt 5.2 and later can read additional 4
bytes which breaks following data, leading to network request just hangs
forever.

Adding stream version fixes this problem.

As cache format changed, cache version bumped.

Task-number: QTBUG-36219
Change-Id: I467d8c9fda82bcf9302192f51e7a00d2f6a9ff66
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>

src/network/access/qnetworkdiskcache.cpp

@@ -56,7 +56,7 @@
 
 #define CACHE_POSTFIX QLatin1String(".d")
 #define PREPARED_SLASH QLatin1String("prepared/")
-#define CACHE_VERSION 7
+#define CACHE_VERSION 8
 #define DATA_DIR QLatin1String("data")
 
 #define MAX_COMPRESSION_SIZE (1024 * 1024 * 3)
@@ -686,6 +686,7 @@ void QCacheItem::writeHeader(QFile *device) const
 
     out << qint32(CacheMagic);
     out << qint32(CurrentCacheVersion);
+    out << static_cast<qint32>(out.version());
     out << metaData;
     bool compressed = canCompress();
     out << compressed;
@@ -719,6 +720,13 @@ bool QCacheItem::read(QFile *device, bool readData)
     if (v != CurrentCacheVersion)
         return false;
 
+    qint32 streamVersion;
+    in >> streamVersion;
+    // Default stream version is also the highest we can handle
+    if (streamVersion > in.version())
+        return false;
+    in.setVersion(streamVersion);
+
     bool compressed;
     QByteArray dataBA;
     in >> metaData;

tests/auto/network/access/qnetworkdiskcache/tst_qnetworkdiskcache.cpp

@@ -85,6 +85,9 @@ private slots:
     void oldCacheVersionFile_data();
     void oldCacheVersionFile();
 
+    void streamVersion_data();
+    void streamVersion();
+
     void sync();
 
     void crashWhenParentingCache();
@@ -568,6 +571,74 @@ void tst_QNetworkDiskCache::oldCacheVersionFile()
     }
 }
 
+void tst_QNetworkDiskCache::streamVersion_data()
+{
+    QTest::addColumn<int>("version");
+    QTest::newRow("Qt 5.1") << int(QDataStream::Qt_5_1);
+    QDataStream ds;
+    QTest::newRow("current") << ds.version();
+    QTest::newRow("higher than current") << ds.version() + 1;
+}
+
+void tst_QNetworkDiskCache::streamVersion()
+{
+    SubQNetworkDiskCache cache;
+    QUrl url(EXAMPLE_URL);
+    cache.setupWithOne(tempDir.path(), url);
+
+    QString cacheFile;
+    // find the file
+    QStringList files = countFiles(cache.cacheDirectory());
+    foreach (const QString &file, files) {
+        QFileInfo info(file);
+        if (info.isFile()) {
+            cacheFile = file;
+            break;
+        }
+    }
+
+    QFile file(cacheFile);
+    QVERIFY(file.open(QFile::ReadWrite|QIODevice::Truncate));
+    QDataStream out(&file);
+    QFETCH(int, version);
+    if (version < out.version())
+        out.setVersion(version);
+    out << qint32(0xe8);    // cache magic
+    // Following code works only for cache file version 8 and should be updated on version change
+    out << qint32(8);
+    out << qint32(version);
+
+    QNetworkCacheMetaData md;
+    md.setUrl(url);
+    QNetworkCacheMetaData::RawHeader header("content-type", "text/html");
+    QNetworkCacheMetaData::RawHeaderList list;
+    list.append(header);
+    md.setRawHeaders(list);
+    md.setLastModified(QDateTime::currentDateTimeUtc().toOffsetFromUtc(3600));
+    out << md;
+
+    bool compressed = true;
+    out << compressed;
+
+    QByteArray data("Hello World!");
+    out << qCompress(data);
+
+    file.close();
+
+    QNetworkCacheMetaData cachedMetaData = cache.call_fileMetaData(cacheFile);
+    if (version > out.version()) {
+        QVERIFY(!cachedMetaData.isValid());
+        QVERIFY(!QFile::exists(cacheFile));
+    } else {
+        QVERIFY(cachedMetaData.isValid());
+        QVERIFY(QFile::exists(cacheFile));
+        QIODevice *dataDevice = cache.data(url);
+        QVERIFY(dataDevice != 0);
+        QByteArray cachedData = dataDevice->readAll();
+        QCOMPARE(cachedData, data);
+    }
+}
+
 class Runner : public QThread
 {