QDataStream: adjust containers' deserialization in transaction mode

If an error occurs during the transaction, we should prevent the
containers from being successfully read. So, check the status of the
stream before reading the container, because the deserialization
procedure temporarily resets it on entry.

Task-number: QTBUG-54022
Change-Id: Ie955c2fa3e449374f0f8403f00e487efa2bfdaf3
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/corelib/io/qdatastream.h b/src/corelib/io/qdatastream.h
index 260dd519e3..e8634fddef 100644
--- a/src/corelib/io/qdatastream.h
+++ b/src/corelib/io/qdatastream.h
@@ -63,6 +63,9 @@ template <class Key, class T> class QMap;
 
 #if !defined(QT_NO_DATASTREAM) || defined(QT_BOOTSTRAPPED)
 class QDataStreamPrivate;
+namespace QtPrivate {
+class StreamStateSaver;
+}
 class Q_CORE_EXPORT QDataStream
 {
 public:
@@ -192,6 +195,7 @@ private:
     Status q_status;
 
     int readBlock(char *data, int len);
+    friend class QtPrivate::StreamStateSaver;
 };
 
 namespace QtPrivate {
@@ -201,7 +205,8 @@ class StreamStateSaver
 public:
     inline StreamStateSaver(QDataStream *s) : stream(s), oldStatus(s->status())
     {
-        stream->resetStatus();
+        if (!stream->dev || !stream->dev->isTransactionStarted())
+            stream->resetStatus();
     }
     inline ~StreamStateSaver()
     {