Break destruction cycle between DownloadItem and WebEngineProfile

All QQWebEngineDownloadItem objects are destructed as child objects
of QQWebEngineProfile. However, they try to 'call back' to the
already half-destructed QQWebEngineProfile object to unregister
themselves.

Avoid this by tracking the lifetime of the QWebEngineProfile with
a QPointer.

Task-number: QTBUG-48088
Change-Id: Ie6a76440ad9f37d7cbc38b4ce35bf5da785d0e2a
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>

4 files changed, 14 insertions, 7 deletions

diff --git a/src/webengine/api/qquickwebenginedownloaditem.cpp b/src/webengine/api/qquickwebenginedownloaditem.cpp
index 89fe688a4..e04cff2c4 100644
--- a/src/webengine/api/qquickwebenginedownloaditem.cpp
+++ b/src/webengine/api/qquickwebenginedownloaditem.cpp
@@ -58,7 +58,7 @@ static inline QQuickWebEngineDownloadItem::DownloadState toDownloadState(int sta
     }
 }
 
-QQuickWebEngineDownloadItemPrivate::QQuickWebEngineDownloadItemPrivate(QQuickWebEngineProfilePrivate *p)
+QQuickWebEngineDownloadItemPrivate::QQuickWebEngineDownloadItemPrivate(QQuickWebEngineProfile *p)
     : profile(p)
     , downloadId(-1)
     , downloadState(QQuickWebEngineDownloadItem::DownloadCancelled)
@@ -69,7 +69,8 @@ QQuickWebEngineDownloadItemPrivate::QQuickWebEngineDownloadItemPrivate(QQuickWeb
 
 QQuickWebEngineDownloadItemPrivate::~QQuickWebEngineDownloadItemPrivate()
 {
-    profile->downloadDestroyed(downloadId);
+    if (profile)
+        profile->d_ptr->downloadDestroyed(downloadId);
 }
 
 /*!
@@ -150,8 +151,10 @@ void QQuickWebEngineDownloadItem::cancel()
 
     // We directly cancel the download if the user cancels before
     // it even started, so no need to notify the profile here.
-    if (state == QQuickWebEngineDownloadItem::DownloadInProgress)
-        d->profile->cancelDownload(d->downloadId);
+    if (state == QQuickWebEngineDownloadItem::DownloadInProgress) {
+        if (d->profile)
+            d->profile->d_ptr->cancelDownload(d->downloadId);
+    }
 }
 
 /*!
diff --git a/src/webengine/api/qquickwebenginedownloaditem_p_p.h b/src/webengine/api/qquickwebenginedownloaditem_p_p.h
index c858693e0..230f322b5 100644
--- a/src/webengine/api/qquickwebenginedownloaditem_p_p.h
+++ b/src/webengine/api/qquickwebenginedownloaditem_p_p.h
@@ -50,19 +50,21 @@
 
 #include "browser_context_adapter_client.h"
 #include "qquickwebenginedownloaditem_p.h"
+#include "qquickwebengineprofile_p.h"
 #include <private/qtwebengineglobal_p.h>
 #include <QString>
+#include <QPointer>
 
 QT_BEGIN_NAMESPACE
 class QQuickWebEngineProfilePrivate;
 
 class QQuickWebEngineDownloadItemPrivate {
     QQuickWebEngineDownloadItem *q_ptr;
-    QQuickWebEngineProfilePrivate* profile;
+    QPointer<QQuickWebEngineProfile> profile;
     friend class QQuickWebEngineProfilePrivate;
 public:
     Q_DECLARE_PUBLIC(QQuickWebEngineDownloadItem)
-    QQuickWebEngineDownloadItemPrivate(QQuickWebEngineProfilePrivate *p);
+    QQuickWebEngineDownloadItemPrivate(QQuickWebEngineProfile *p);
     ~QQuickWebEngineDownloadItemPrivate();
 
     quint32 downloadId;
diff --git a/src/webengine/api/qquickwebengineprofile.cpp b/src/webengine/api/qquickwebengineprofile.cpp
index bff640d32..68884f967 100644
--- a/src/webengine/api/qquickwebengineprofile.cpp
+++ b/src/webengine/api/qquickwebengineprofile.cpp
@@ -85,7 +85,7 @@ void QQuickWebEngineProfilePrivate::downloadRequested(DownloadItemInfo &info)
     Q_Q(QQuickWebEngineProfile);
 
     Q_ASSERT(!m_ongoingDownloads.contains(info.id));
-    QQuickWebEngineDownloadItemPrivate *itemPrivate = new QQuickWebEngineDownloadItemPrivate(this);
+    QQuickWebEngineDownloadItemPrivate *itemPrivate = new QQuickWebEngineDownloadItemPrivate(q);
     itemPrivate->downloadId = info.id;
     itemPrivate->downloadState = QQuickWebEngineDownloadItem::DownloadRequested;
     itemPrivate->totalBytes = info.totalBytes;
diff --git a/src/webengine/api/qquickwebengineprofile_p.h b/src/webengine/api/qquickwebengineprofile_p.h
index d07428cab..323721bd0 100644
--- a/src/webengine/api/qquickwebengineprofile_p.h
+++ b/src/webengine/api/qquickwebengineprofile_p.h
@@ -138,6 +138,8 @@ private:
     friend class QQuickWebEngineSettings;
     friend class QQuickWebEngineSingleton;
     friend class QQuickWebEngineViewPrivate;
+    friend class QQuickWebEngineDownloadItem;
+    friend class QQuickWebEngineDownloadItemPrivate;
     QScopedPointer<QQuickWebEngineProfilePrivate> d_ptr;
 };