JavaScriptFilter: Use QScriptEngine to avoid endless loops

QJSEngine does not provide a means to interrupt the
evaluation when then engine stucks in an endless loop.

The (deprecated) QScriptEngine does allow this,
so use this for now. As QBS also needs QScriptEngine,
no extra dependency is created. For Qt installations
without QtScript, the JavaScriptFilter is not compiled.

Task-number: QTCREATORBUG-19690
Change-Id: I172b7e7042eea0d40a765c836b2d1c57b6a529e6
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/coreplugin/coreplugin.qbs

@@ -17,11 +17,18 @@ Project {
             condition: qbs.targetOS.contains("windows")
         }
 
+        Depends { name: "Qt.script"; required: false }
+
         Depends { name: "Utils" }
         Depends { name: "Aggregation" }
 
         Depends { name: "app_version_header" }
 
+        Properties {
+            condition: Qt.script.present
+            cpp.defines: base.concat("WITH_JAVASCRIPTFILTER")
+        }
+
         cpp.dynamicLibraries: {
             if (qbs.targetOS.contains("windows"))
                 return ["ole32", "user32"]
@@ -343,8 +350,6 @@ Project {
                 "filesystemfilter.ui",
                 "ilocatorfilter.cpp",
                 "ilocatorfilter.h",
-                "javascriptfilter.cpp",
-                "javascriptfilter.h",
                 "locatorconstants.h",
                 "locatorfiltersfilter.cpp",
                 "locatorfiltersfilter.h",
@@ -364,6 +369,16 @@ Project {
             ]
         }
 
+        Group {
+            name: "Locator Javascript Filter"
+            condition: Qt.script.present
+            prefix: "locator/"
+            files: [
+                "javascriptfilter.cpp",
+                "javascriptfilter.h",
+            ]
+        }
+
         Group {
             name: "Locator_mac"
             condition: qbs.targetOS.contains("macos")

src/plugins/coreplugin/locator/javascriptfilter.cpp

@@ -27,14 +27,16 @@
 
 #include <QClipboard>
 #include <QGuiApplication>
-#include <QJSEngine>
+#include <QScriptEngine>
+#include <QTimer>
 
 namespace Core {
 namespace Internal {
 
 enum JavaScriptAction
 {
-    ResetEngine = QVariant::UserType + 1
+    ResetEngine = QVariant::UserType + 1,
+    AbortEngine
 };
 
 JavaScriptFilter::JavaScriptFilter()
@@ -66,13 +68,25 @@ QList<LocatorFilterEntry> JavaScriptFilter::matchesFor(
     if (entry.trimmed().isEmpty()) {
         entries.append({this, tr("Reset Engine"), QVariant(ResetEngine, nullptr)});
     } else {
-        const QString result = m_engine->evaluate(entry).toString();
+        bool aborted = false;
-        const QString expression = entry + " = " + result;
 
+        QTimer::singleShot(1000, this, [this, &aborted]() {
+            m_engine->abortEvaluation();
+            aborted = true;
+        });
+
+        const QString result = m_engine->evaluate(entry).toString();
+
+        if (aborted) {
+            const QString message = entry + " = " + tr("Engine aborted after timeout.");
+            entries.append({this, message, QVariant(AbortEngine, nullptr)});
+        } else {
+            const QString expression = entry + " = " + result;
             entries.append({this, expression, QVariant()});
             entries.append({this, tr("Copy to clipboard: %1").arg(result), result});
             entries.append({this, tr("Copy to clipboard: %1").arg(expression), expression});
         }
+    }
 
     return entries;
 }
@@ -104,7 +118,7 @@ void JavaScriptFilter::refresh(QFutureInterface<void> &future)
 
 void JavaScriptFilter::setupEngine()
 {
-    m_engine.reset(new QJSEngine);
+    m_engine.reset(new QScriptEngine);
     m_engine->evaluate(
                 "function abs(x) { return Math.abs(x); }\n"
                 "function acos(x) { return Math.acos(x); }\n"

src/plugins/coreplugin/locator/javascriptfilter.h

@@ -30,7 +30,7 @@
 #include <memory>
 
 QT_BEGIN_NAMESPACE
-class QJSEngine;
+class QScriptEngine;
 QT_END_NAMESPACE
 
 namespace Core {
@@ -53,7 +53,7 @@ public:
 private:
     void setupEngine();
 
-    mutable std::unique_ptr<QJSEngine> m_engine;
+    mutable std::unique_ptr<QScriptEngine> m_engine;
 };
 
 } // namespace Internal

src/plugins/coreplugin/locator/locator.cpp

@@ -122,8 +122,10 @@ void Locator::initialize(CorePlugin *corePlugin, const QStringList &, QString *)
 
     new LocatorManager(this);
 
+#ifdef WITH_JAVASCRIPTFILTER
     m_javaScriptFilter = new JavaScriptFilter;
     m_corePlugin->addObject(m_javaScriptFilter);
+#endif
 
     m_openDocumentsFilter = new OpenDocumentsFilter;
     m_corePlugin->addObject(m_openDocumentsFilter);

src/plugins/coreplugin/locator/locator.pri

@@ -15,8 +15,7 @@ HEADERS += \
     $$PWD/executefilter.h \
     $$PWD/locatorsearchutils.h \
     $$PWD/locatorsettingspage.h \
-    $$PWD/externaltoolsfilter.h \
+    $$PWD/externaltoolsfilter.h
-    $$PWD/javascriptfilter.h
 
 SOURCES += \
     $$PWD/locator.cpp \
@@ -33,7 +32,18 @@ SOURCES += \
     $$PWD/locatorsearchutils.cpp \
     $$PWD/locatorsettingspage.cpp \
     $$PWD/externaltoolsfilter.cpp \
+
+qtHaveModule(script) {
+    QT *= script
+
+    DEFINES += WITH_JAVASCRIPTFILTER
+
+    HEADERS += \
+        $$PWD/javascriptfilter.h
+
+    SOURCES += \
         $$PWD/javascriptfilter.cpp
+}
 
 FORMS += \
     $$PWD/filesystemfilter.ui \