Handle exceptions while compiling v8 bindings

Previously, no exception handling existed, which could cause a crash
if an invalid v8 binding expression was generated.  Such invalid
bindings should usually be rewritten into valid form by the bindings
rewriter, but in some cases it is too costly to do so, so we need
to handle exceptions.

Task-number: QTBUG-24064
Task-number: QTBUG-23387
Change-Id: I7da12a936780a561c9e9cad3a4a7b62c06d6973e
Reviewed-by: Alan Alpert <alan.alpert@nokia.com>

src/declarative/qml/qdeclarativevme.cpp

@@ -826,9 +826,11 @@ QObject *QDeclarativeVME::run(QList<QDeclarativeError> *errors,
                 CTXT->v8bindings->configBinding(instr.value, target, scope, 
                                                 instr.property, instr.line,
                                                 instr.column);
-            bindValues.push(binding);
-            binding->m_mePtr = &bindValues.top();
-            binding->addToObject(target, QDeclarativePropertyPrivate::bindingIndex(instr.property));
+            if (binding) {
+                bindValues.push(binding);
+                binding->m_mePtr = &bindValues.top();
+                binding->addToObject(target, QDeclarativePropertyPrivate::bindingIndex(instr.property));
+            }
         QML_END_INSTR(StoreV8Binding)
 
         QML_BEGIN_INSTR(StoreValueSource)

src/declarative/qml/v8/qv8bindings.cpp

@@ -167,18 +167,41 @@ QV8Bindings::QV8Bindings(const QString &program, int index, int line,
         v8::HandleScope handle_scope;
         v8::Context::Scope scope(engine->context());
 
-        v8::Local<v8::Script> script = engine->qmlModeCompile(program, compiled->name, line);
-        v8::Local<v8::Value> result = script->Run(engine->contextWrapper()->sharedContext());
+        v8::Local<v8::Script> script;
+        bool compileFailed = false;
+        {
+            v8::TryCatch try_catch;
+            script = engine->qmlModeCompile(program, compiled->name, line);
+            if (try_catch.HasCaught()) {
+                // The binding was not compiled.  There are some exceptional cases which the
+                // expression rewriter does not rewrite properly (e.g., \r-terminated lines
+                // are not rewritten correctly but this bug is demed out-of-scope to fix for
+                // performance reasons; see QTBUG-24064).
+                compileFailed = true;
+                QDeclarativeError error;
+                error.setDescription(QString(QLatin1String("Exception occurred during compilation of binding at line: %1")).arg(line));
+                v8::Local<v8::Message> message = try_catch.Message();
+                if (!message.IsEmpty())
+                    QDeclarativeExpressionPrivate::exceptionToError(message, error);
+                QDeclarativeEnginePrivate::get(engine->engine())->warning(error);
+                compiled->v8bindings[index] = qPersistentNew(v8::Array::New());
+            }
+        }
 
-        if (result->IsArray()) 
-            compiled->v8bindings[index] = qPersistentNew(v8::Local<v8::Array>::Cast(result));
+        if (!compileFailed) {
+            v8::Local<v8::Value> result = script->Run(engine->contextWrapper()->sharedContext());
+            if (result->IsArray()) {
+                compiled->v8bindings[index] = qPersistentNew(v8::Local<v8::Array>::Cast(result));
+            }
+        }
     }
 
     url = compiled->url;
     functions = qPersistentNew(compiled->v8bindings[index]);
     bindingsCount = functions->Length();
-    bindings = new QV8Bindings::Binding[bindingsCount];
-
+    if (bindingsCount)
+        bindings = new QV8Bindings::Binding[bindingsCount];
+
     setContext(context);
 }
 
@@ -195,6 +218,9 @@ QDeclarativeAbstractBinding *QV8Bindings::configBinding(int index, QObject *targ
                                                         const QDeclarativePropertyData &p,
                                                         int line, int column)
 {
+    if (bindingsCount <= index) // initialization failed.
+        return 0;
+
     QV8Bindings::Binding *rv = bindings + index;
 
     rv->line = line;

tests/auto/declarative/qdeclarativeecmascript/data/v8bindingException.qml

@@ -0,0 +1,21 @@
+import QtQuick 2.0
+
+// This test uses a multi-line string which has \r-terminated
+// string fragments.  The expression rewriter deliberately doesn't
+// handle \r-terminated string fragments (see QTBUG-24064) and thus
+// this test ensures that we don't crash when we encounter a
+// non-compilable binding such as this one.
+
+Item {
+    id: root
+
+    Component {
+        id: comp
+        Text {
+            property var value: ","
+            text: 'multi            line ' + value + 'str            ings'
+        }
+    }
+
+    Component.onCompleted: comp.createObject(root, { "value": undefined })
+}

tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp

@@ -113,6 +113,7 @@ private slots:
     void exceptionClearsOnReeval();
     void exceptionSlotProducesWarning();
     void exceptionBindingProducesWarning();
+    void compileInvalidBinding();
     void transientErrors();
     void shutdownErrors();
     void compositePropertyType();
@@ -1562,6 +1563,17 @@ void tst_qdeclarativeecmascript::exceptionBindingProducesWarning()
     delete object;
 }
 
+void tst_qdeclarativeecmascript::compileInvalidBinding()
+{
+    // QTBUG-23387: ensure that invalid bindings don't cause a crash.
+    QDeclarativeComponent component(&engine, testFileUrl("v8bindingException.qml"));
+    QString warning = component.url().toString() + ":16: SyntaxError: Unexpected token ILLEGAL";
+    QTest::ignoreMessage(QtWarningMsg, warning.toLatin1().constData());
+    QObject *object = component.create();
+    QVERIFY(object != 0);
+    delete object;
+}
+
 static int transientErrorsMsgCount = 0;
 static void transientErrorsMsgHandler(QtMsgType, const char *)
 {