Fix broadcasts calling themselves

Author: adazem009

src/blocks/eventblocks.cpp

@@ -44,12 +44,12 @@ void EventBlocks::compileWhenBroadcastReceived(Compiler *compiler)
 
 unsigned int EventBlocks::broadcast(VirtualMachine *vm)
 {
-    vm->engine()->broadcast(vm->engine()->findBroadcast(vm->getInput(0, 1)->toString()));
+    vm->engine()->broadcast(vm->engine()->findBroadcast(vm->getInput(0, 1)->toString()), vm);
     return 1;
 }
 
 unsigned int EventBlocks::broadcastByIndex(VirtualMachine *vm)
 {
-    vm->engine()->broadcast(vm->getInput(0, 1)->toLong());
+    vm->engine()->broadcast(vm->getInput(0, 1)->toLong(), vm);
     return 1;
 }

src/engine/engine.cpp

@@ -121,7 +121,9 @@ void Engine::frame()
         m_breakFrame = false;
 
         do {
-            m_scriptPositions[i] = script->run(m_scriptPositions[i]);
+            auto ret = script->run(m_scriptPositions[i]);
+            if (script->savePos())
+                m_scriptPositions[i] = ret;
             if (script->atEnd())
                 m_scriptsToRemove.push_back(script);
         } while (!script->atEnd() && !m_breakFrame);
@@ -181,7 +183,7 @@ void Engine::startScript(std::shared_ptr<Block> topLevelBlock, std::shared_ptr<T
 }
 
 /*! Starts the script of the broadcast with the given index. */
-void libscratchcpp::Engine::broadcast(unsigned int index)
+void libscratchcpp::Engine::broadcast(unsigned int index, VirtualMachine *sourceScript)
 {
     const std::vector<VirtualMachine *> scripts = m_broadcastMap[index];
     for (auto vm : scripts) {
@@ -190,6 +192,8 @@ void libscratchcpp::Engine::broadcast(unsigned int index)
             // Reset the script if it's already running
             auto i = it - m_runningScripts.begin();
             m_scriptPositions[i] = m_runningScripts[i]->bytecode();
+            if (vm == sourceScript)
+                vm->stop(false, true);
         } else {
             m_runningScripts.push_back(vm);
             m_scriptPositions.push_back(vm->bytecode());

src/engine/engine.h

@@ -35,7 +35,7 @@ class LIBSCRATCHCPP_EXPORT Engine
         void start();
         void stop();
         void startScript(std::shared_ptr<Block> topLevelBlock, std::shared_ptr<Target> target);
-        void broadcast(unsigned int index);
+        void broadcast(unsigned int index, VirtualMachine *sourceScript);
         void stopScript(VirtualMachine *vm);
         void stopTarget(Target *target, VirtualMachine *exceptScript);
         void run();

src/engine/virtualmachine.cpp

@@ -614,6 +614,19 @@ do_list_get_item : {
 
 do_exec:
     FREE_REGS(m_functions[*++pos](this));
+    if (m_stop) {
+        m_stop = false;
+        if (m_regCount > 0) {
+            std::cout << "warning: VM: " << m_regCount << " registers were leaked by the script; this is most likely a bug in the VM or in the compiler" << std::endl;
+        }
+        m_callTree.clear();
+        m_procedureArgTree.clear();
+        m_procedureArgs = nullptr;
+        m_nextProcedureArgs = nullptr;
+        if (!m_atomic)
+            m_engine->breakFrame();
+        return pos;
+    }
     DISPATCH();
 
 do_init_procedure:

src/engine/virtualmachine.h

@@ -111,9 +111,24 @@ class LIBSCRATCHCPP_EXPORT VirtualMachine
         unsigned int *run();
         unsigned int *run(unsigned int *pos);
 
+        /*!
+         * Use this to stop the script from a function.
+         * \param[in] savePos Changes the return value of savePos().
+         * \param[in] breakAtomic Whether to break the frame after stopping the script.
+         */
+        void stop(bool savePos = true, bool breakAtomic = false)
+        {
+            m_stop = true;
+            m_savePos = savePos;
+            m_atomic = !breakAtomic;
+        }
+
         /*! Returns true if the VM has reached the vm::OP_HALT instruction. */
         bool atEnd() const { return m_atEnd; };
 
+        /*! Used by Engine to check whether the position can be preserved. */
+        bool savePos() const { return m_savePos; }
+
     private:
         static inline const unsigned int instruction_arg_count[] = {
             0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0
@@ -138,6 +153,8 @@ class LIBSCRATCHCPP_EXPORT VirtualMachine
         std::vector<Value> *m_procedureArgs = nullptr;
         std::vector<Value> *m_nextProcedureArgs = nullptr;
         bool m_atomic;
+        bool m_stop = false;
+        bool m_savePos = true;
 
         unsigned int **m_procedures = nullptr;
         std::vector<unsigned int *> m_proceduresVector;