network internals: do not try to cache a deleted entry

We were keeping a dangling pointer to a non-existent QIODevice around
which would lead to a crash.

This is not reproducible in Qt5 anymore.

Task-number: QTBUG-17400
Change-Id: I19af701a42e48c05d04dec18eca9f1bfc7e1f4bb
Reviewed-by: Richard J. Moore <rich@kde.org>

2 files changed, 12 insertions, 0 deletions

diff --git a/src/network/access/qnetworkreplyimpl.cpp b/src/network/access/qnetworkreplyimpl.cpp
index 0495658..7ee7386 100644
--- a/src/network/access/qnetworkreplyimpl.cpp
+++ b/src/network/access/qnetworkreplyimpl.cpp
@@ -505,6 +505,13 @@ void QNetworkReplyImplPrivate::_q_cacheDestroyed()
     cacheEnabled = false;
 }
 
+void QNetworkReplyImplPrivate::_q_cacheSaveDeviceAboutToClose()
+{
+    // do not keep a dangling pointer to the device around (device
+    // is closing because e.g. QAbstractNetworkCache::remove() was called).
+    cacheSaveDevice = 0;
+}
+
 void QNetworkReplyImplPrivate::completeCacheSave()
 {
     Q_Q(QNetworkReplyImpl);
@@ -565,6 +572,9 @@ void QNetworkReplyImplPrivate::initCacheSaveDevice()
 
     cacheSaveDevice = networkCache()->prepare(metaData);
 
+    if (cacheSaveDevice)
+        q->connect(cacheSaveDevice, SIGNAL(aboutToClose()), SLOT(_q_cacheSaveDeviceAboutToClose()));
+
     if (!cacheSaveDevice || (cacheSaveDevice && !cacheSaveDevice->isOpen())) {
         if (cacheSaveDevice && !cacheSaveDevice->isOpen())
             qCritical("QNetworkReplyImpl: network cache returned a device that is not open -- "
diff --git a/src/network/access/qnetworkreplyimpl_p.h b/src/network/access/qnetworkreplyimpl_p.h
index 3947e79..d59e6a0 100644
--- a/src/network/access/qnetworkreplyimpl_p.h
+++ b/src/network/access/qnetworkreplyimpl_p.h
@@ -105,6 +105,7 @@ public:
     Q_PRIVATE_SLOT(d_func(), void _q_networkSessionFailed())
 #endif
     Q_PRIVATE_SLOT(d_func(), void _q_cacheDestroyed())
+    Q_PRIVATE_SLOT(d_func(), void _q_cacheSaveDeviceAboutToClose())
 };
 
 class QNetworkReplyImplPrivate: public QNetworkReplyPrivate
@@ -142,6 +143,7 @@ public:
     void _q_networkSessionFailed();
 #endif
     void _q_cacheDestroyed();
+    void _q_cacheSaveDeviceAboutToClose();
 
     void setup(QNetworkAccessManager::Operation op, const QNetworkRequest &request,
                QIODevice *outgoingData);