fix #256: Do not free registers of running scripts

Author: adazem009

src/engine/virtualmachine.cpp

@@ -164,19 +164,26 @@ void VirtualMachine::replaceReturnValue(const Value &v, unsigned int offset)
 /*! Continues running the script from last position (the first instruction is skipped). */
 void VirtualMachine::run()
 {
+    impl->running = true;
+
     unsigned int *ret = impl->run(impl->pos);
     assert(ret);
+
     if (impl->savePos)
         impl->pos = ret;
+
+    impl->running = false;
 }
 
 /*! Jumps back to the initial position. */
 void VirtualMachine::reset()
 {
     assert(impl->bytecode);
     impl->pos = impl->bytecode;
-    impl->regCount = 0;
     impl->atEnd = false;
+
+    if (!impl->running) // Registers will be freed when the script stops running
+        impl->regCount = 0;
 }
 
 /*! Moves back to the last vm::OP_CHECKPOINT instruction in the bytecode. */

src/engine/virtualmachine_p.h

@@ -43,6 +43,7 @@ struct VirtualMachinePrivate
         Script *script = nullptr;
         unsigned int *pos = nullptr;
         unsigned int *checkpoint = nullptr;
+        bool running = false;
         bool atEnd = false;
         std::vector<Loop> loops;
         std::vector<unsigned int *> callTree;

test/engine/engine_test.cpp

@@ -521,3 +521,11 @@ TEST(EngineTest, NoCrashAfterStop)
     ASSERT_TRUE(p.load());
     p.run();
 }
+
+TEST(EngineTest, NoCrashOnBroadcastSelfCall)
+{
+    // Regtest for #256
+    Project p("regtest_projects/256_broadcast_self_call_crash.sb3");
+    ASSERT_TRUE(p.load());
+    p.run();
+}