Invalidate QScriptPrograms when engine is destroyed

If the engine is destroyed before the program, the program
must be invalidated; otherwise the program destructor will
access a stale engine pointer, which can cause a crash
(it crashes on Symbian, but "only" gives a Valgrind warning
on Linux for our autotests).

We need to keep track of all associated programs, just like
we already do for values and strings. This fix follows the
exact same pattern, but uses a QSet to keep the patch minimal.

No new tests, but the evaluateProgram() test runs successfully
on Symbian now, and there are no more Valgrind warnings.

Task-number: QTBUG-16987
Reviewed-by: Olivier Goffart

1 files changed, 14 insertions, 7 deletions

diff --git a/src/script/api/qscriptprogram.cpp b/src/script/api/qscriptprogram.cpp
index da103bb..31af9a0 100644
--- a/src/script/api/qscriptprogram.cpp
+++ b/src/script/api/qscriptprogram.cpp
@@ -64,6 +64,7 @@ QScriptProgramPrivate::~QScriptProgramPrivate()
     if (engine) {
         QScript::APIShim shim(engine);
         _executable.clear();
+        engine->unregisterScriptProgram(this);
     }
 }
 
@@ -78,7 +79,10 @@ JSC::EvalExecutable *QScriptProgramPrivate::executable(JSC::ExecState *exec,
     if (_executable) {
         if (eng == engine)
             return _executable.get();
-        _executable = 0;
+        // "Migrating" to another engine; clean up old state
+        QScript::APIShim shim(engine);
+        _executable.clear();
+        engine->unregisterScriptProgram(this);
     }
     WTF::PassRefPtr<QScript::UStringSourceProviderWithFeedback> provider
         = QScript::UStringSourceProviderWithFeedback::create(sourceCode, fileName, firstLineNumber, eng);
@@ -86,10 +90,19 @@ JSC::EvalExecutable *QScriptProgramPrivate::executable(JSC::ExecState *exec,
     JSC::SourceCode source(provider, firstLineNumber); //after construction of SourceCode provider variable will be null.
     _executable = JSC::EvalExecutable::create(exec, source);
     engine = eng;
+    engine->registerScriptProgram(this);
     isCompiled = false;
     return _executable.get();
 }
 
+void QScriptProgramPrivate::detachFromEngine()
+{
+    _executable.clear();
+    sourceId = -1;
+    isCompiled = false;
+    engine = 0;
+}
+
 /*!
   Constructs a null QScriptProgram.
 */
@@ -122,9 +135,6 @@ QScriptProgram::QScriptProgram(const QScriptProgram &other)
 */
 QScriptProgram::~QScriptProgram()
 {
-    //    Q_D(QScriptProgram);
-    //    if (d->engine && (d->ref == 1))
-    //      d->engine->unregisterScriptProgram(d);
 }
 
 /*!
@@ -132,9 +142,6 @@ QScriptProgram::~QScriptProgram()
 */
 QScriptProgram &QScriptProgram::operator=(const QScriptProgram &other)
 {
-  //    if (d_func() && d_func()->engine && (d_func()->ref == 1))
-      //        d_func()->engine->unregisterScriptProgram(d_func());
-  //    }
     d_ptr = other.d_ptr;
     return *this;
 }