Fix crashes when dealing with malformed qml filesv2.1.0-rc

Attempting to determine the qml file type (script or qml-stream)
assumed there was always a valid root object. If the qml file had a bug
that caused loading it to fail, that assumption caused a crash.

Task-number: QT3DS-2381
Change-Id: I7016540fe48593dff3f01107dc6826f1f6d3929f
Reviewed-by: Antti Määttä <antti.maatta@qt.io>

4 files changed, 36 insertions, 23 deletions

diff --git a/src/Authoring/Studio/Application/StudioApp.cpp b/src/Authoring/Studio/Application/StudioApp.cpp
index 91b1ab92..a5328c13 100644
--- a/src/Authoring/Studio/Application/StudioApp.cpp
+++ b/src/Authoring/Studio/Application/StudioApp.cpp
@@ -1990,9 +1990,11 @@ QSize CStudioApp::getRenderableSize(const QString &renderableId)
                     r.m_size = PresentationFile::readSize(path);
                 } else { // QML stream
                     QQmlApplicationEngine qmlEngine(path);
-                    QQuickItem *item = qobject_cast<QQuickItem *>(qmlEngine.rootObjects().at(0));
-                    if (item)
-                        r.m_size = QSize(qRound(item->width()), qRound(item->height()));
+                    if (qmlEngine.rootObjects().size() > 0) {
+                        QQuickItem *item = qobject_cast<QQuickItem *>(qmlEngine.rootObjects().at(0));
+                        if (item)
+                            r.m_size = QSize(qRound(item->width()), qRound(item->height()));
+                    }
                 }
             }
             return r.m_size;
diff --git a/src/Authoring/Studio/Palettes/Project/ProjectFileSystemModel.cpp b/src/Authoring/Studio/Palettes/Project/ProjectFileSystemModel.cpp
index 643b6690..1588a745 100644
--- a/src/Authoring/Studio/Palettes/Project/ProjectFileSystemModel.cpp
+++ b/src/Authoring/Studio/Palettes/Project/ProjectFileSystemModel.cpp
@@ -440,19 +440,24 @@ void ProjectFileSystemModel::importUrl(QDir &targetDir, const QUrl &url)
         QObject *qmlRoot = nullptr;
         if (extension == QLatin1String("qml")) {
             qmlEngine.load(sourceFile);
-            const char *rootClassName = qmlEngine.rootObjects().at(0)
-                                        ->metaObject()->superClass()->className();
-
-            // the assumption here is that any qml that is not a behavior is a qml stream
-            if (strcmp(rootClassName, "Q3DStudio::Q3DSQmlBehavior") != 0) { // not a behavior
-                qmlRoot = qmlEngine.rootObjects().at(0);
-
-                // put the qml in the correct folder
-                if (targetDir.path().endsWith(QLatin1String("/scripts"))) {
-                    const QString path(QStringLiteral("../qml streams"));
-                    targetDir.mkpath(path); // create the folder if doesn't exist (i.e. old project)
-                    targetDir.cd(path);
+            if (qmlEngine.rootObjects().size() > 0) {
+                const char *rootClassName = qmlEngine.rootObjects().at(0)
+                                            ->metaObject()->superClass()->className();
+                // the assumption here is that any qml that is not a behavior is a qml stream
+                if (strcmp(rootClassName, "Q3DStudio::Q3DSQmlBehavior") != 0) { // not a behavior
+                    qmlRoot = qmlEngine.rootObjects().at(0);
+                    // put the qml in the correct folder
+                    if (targetDir.path().endsWith(QLatin1String("/scripts"))) {
+                        const QString path(QStringLiteral("../qml streams"));
+                        targetDir.mkpath(path); // create the folder if doesn't exist
+                        targetDir.cd(path);
+                    }
                 }
+            } else {
+                // Invalid qml file, block import
+                g_StudioApp.GetDialogs()->DisplayKnownErrorDialog(
+                            tr("Failed to parse '%1'\nAborting import.").arg(sourceFile));
+                return;
             }
         }
         // Copy the file to target directory
diff --git a/src/Authoring/Studio/Palettes/Project/ProjectView.cpp b/src/Authoring/Studio/Palettes/Project/ProjectView.cpp
index 72964c04..05c68ecd 100644
--- a/src/Authoring/Studio/Palettes/Project/ProjectView.cpp
+++ b/src/Authoring/Studio/Palettes/Project/ProjectView.cpp
@@ -372,9 +372,13 @@ bool ProjectView::isQmlStream(int row) const
         return false;
 
     QQmlApplicationEngine qmlEngine(filePath);
-    const char *rootClassName = qmlEngine.rootObjects().at(0)
-                                ->metaObject()->superClass()->className();
-    return strcmp(rootClassName, "Q3DStudio::Q3DSQmlBehavior") != 0;
+    if (qmlEngine.rootObjects().size() > 0) {
+        const char *rootClassName = qmlEngine.rootObjects().at(0)
+                                    ->metaObject()->superClass()->className();
+        return strcmp(rootClassName, "Q3DStudio::Q3DSQmlBehavior") != 0;
+    } else {
+        return false;
+    }
 }
 
 bool ProjectView::isRefreshable(int row) const
diff --git a/src/Authoring/Studio/Utils/ImportUtils.cpp b/src/Authoring/Studio/Utils/ImportUtils.cpp
index 46ba9efa..2bb4807c 100644
--- a/src/Authoring/Studio/Utils/ImportUtils.cpp
+++ b/src/Authoring/Studio/Utils/ImportUtils.cpp
@@ -57,11 +57,13 @@ SObjectFileType ImportUtils::GetObjectFileTypeForFile(const CFilePath &inFile,
     } else if (theExtension.Compare(CDialogs::GetQmlFileExtension(),
                                     Q3DStudio::CString::ENDOFSTRING, false)) {
         QQmlApplicationEngine qmlEngine(inFile.absoluteFilePath());
-        const char *rootClassName = qmlEngine.rootObjects().at(0)
-                                    ->metaObject()->superClass()->className();
-        bool isQmlStream =  strcmp(rootClassName, "Q3DStudio::Q3DSQmlBehavior") != 0;
-        return isQmlStream ? SObjectFileType(OBJTYPE_QML_STREAM, DocumentEditorFileType::QmlStream)
-                           : SObjectFileType(OBJTYPE_BEHAVIOR, DocumentEditorFileType::Behavior);
+        if (qmlEngine.rootObjects().size() > 0) {
+            const char *rootClassName = qmlEngine.rootObjects().at(0)
+                                        ->metaObject()->superClass()->className();
+            bool isQmlStream =  strcmp(rootClassName, "Q3DStudio::Q3DSQmlBehavior") != 0;
+            return isQmlStream ? SObjectFileType(OBJTYPE_QML_STREAM, DocumentEditorFileType::QmlStream)
+                               : SObjectFileType(OBJTYPE_BEHAVIOR, DocumentEditorFileType::Behavior);
+        } // If qml file is invalid, it will be of unknown type
     } else if (CDialogs::IsFontFileExtension(theExtension)) {
         return SObjectFileType(OBJTYPE_TEXT, DocumentEditorFileType::Font);
     } else if (CDialogs::IsEffectFileExtension(theExtension)) {