Fix XMLHttpRequest when used with QQmlEngine::evaluate

Our XHR implementation insists on a valid QQmlContext when processing
callbacks. This is to protect against callbacks being triggered after
dynamic QML contexts such as delegates have been destroyed.
Unfortunately those checks are too strict and make it impossible to use
XHR from within plain JS scripts (where v4->callingQmlContext() will
return a null pointer).

Dispatching the callbacks in functions that are directly called from
QML/JS is safe and something we can do unconditionally. This applies to
the callbacks triggered from abort() and open() for example.

When we're called from QNetworkAccessManager we should enforce the
continued existence of a QML context only if it was present at send()
time.

Task-number: QTBUG-67337
Change-Id: I8235f6ef407adc3eaeeff4eee72238ba6750afb2
Reviewed-by: Michael Brasser <michael.brasser@live.com>
Reviewed-by: Valery Kotov <vkotov@luxoft.com>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

2 files changed, 37 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlxmlhttprequest/data/noqmlcontext.js b/tests/auto/qml/qqmlxmlhttprequest/data/noqmlcontext.js
new file mode 100644
index 0000000000..adb7269310
--- /dev/null
+++ b/tests/auto/qml/qqmlxmlhttprequest/data/noqmlcontext.js
@@ -0,0 +1,11 @@
+(function(url, resultCollector) {
+        var x = new XMLHttpRequest;
+        x.open("GET", url);
+        x.setRequestHeader("Accept-Language","en-US");
+        x.onreadystatechange = function() {
+            if (x.readyState == XMLHttpRequest.DONE) {
+                resultCollector.responseText = x.responseText
+            }
+        }
+        x.send()
+})
diff --git a/tests/auto/qml/qqmlxmlhttprequest/tst_qqmlxmlhttprequest.cpp b/tests/auto/qml/qqmlxmlhttprequest/tst_qqmlxmlhttprequest.cpp
index 59716acc0d..ecce6515ed 100644
--- a/tests/auto/qml/qqmlxmlhttprequest/tst_qqmlxmlhttprequest.cpp
+++ b/tests/auto/qml/qqmlxmlhttprequest/tst_qqmlxmlhttprequest.cpp
@@ -108,6 +108,8 @@ private slots:
     void text();
     void cdata();
 
+    void noQmlContext();
+
     // Crashes
     // void outstanding_request_at_shutdown();
 
@@ -1243,6 +1245,30 @@ void tst_qqmlxmlhttprequest::cdata()
     QCOMPARE(object->property("status").toInt(), 200);
 }
 
+void tst_qqmlxmlhttprequest::noQmlContext()
+{
+    TestHTTPServer server;
+    QVERIFY2(server.listen(), qPrintable(server.errorString()));
+    QVERIFY(server.wait(testFileUrl("open_network.expect"),
+                        testFileUrl("open_network.reply"),
+                        testFileUrl("testdocument.html")));
+    QUrl url = server.urlString(QStringLiteral("/testdocument.html"));
+
+    QQmlEngine engine;
+
+    QFile f(testFile("noqmlcontext.js"));
+    QVERIFY(f.open(QIODevice::ReadOnly));
+    QString script = QString::fromUtf8(f.readAll());
+    QJSValue testFunction = engine.evaluate(script);
+    QVERIFY(testFunction.isCallable());
+
+    QJSValue resultCollector = engine.newObject();
+
+    testFunction.call(QJSValueList() << url.toString() << resultCollector);
+
+    QTRY_COMPARE(resultCollector.property("responseText").toString(), "QML Rocks!\n");
+ }
+
 void tst_qqmlxmlhttprequest::stateChangeCallingContext()
 {
 #ifdef Q_OS_WIN