fix #379: Skip if statements and loops in repeat until loop correctly

Author: adazem009

src/engine/virtualmachine_p.cpp

@@ -321,8 +321,17 @@ do_repeat_loop_index1 : {
         pos = loopStart;
     } else {
         pos = loopStart;
-        while (*pos != OP_LOOP_END)
+        unsigned int loopCounter = 1;
+        while ((*pos != OP_LOOP_END) || (loopCounter > 0)) {
             pos += instruction_arg_count[*pos++];
+
+            if ((*pos == OP_IF) || (*pos == OP_FOREVER_LOOP) || (*pos == OP_REPEAT_LOOP) || (*pos == OP_UNTIL_LOOP))
+                loopCounter++;
+            else if ((*pos == OP_ENDIF) || (*pos == OP_LOOP_END)) {
+                assert(loopCounter > 0);
+                loopCounter--;
+            }
+        }
     }
     FREE_REGS(1);
     DISPATCH();

test/virtual_machine/virtual_machine_test.cpp

@@ -1637,3 +1637,14 @@ TEST(VirtualMachineTest, NoCrashInNestedIfStatementsWithLoopAndIfElse)
     vm.run();
     ASSERT_EQ(vm.registerCount(), 0);
 }
+
+TEST(VirtualMachineTest, NoCrashInNestedLoopsInRepeatUntilLoop)
+{
+    // Regtest for #379
+    static unsigned int bytecode[] = { OP_START, OP_UNTIL_LOOP, OP_NULL, OP_NOT, OP_BEGIN_UNTIL_LOOP, OP_NULL, OP_REPEAT_LOOP, OP_LOOP_END, OP_LOOP_END, OP_HALT };
+
+    VirtualMachine vm(nullptr, nullptr, nullptr);
+    vm.setBytecode(bytecode);
+    vm.run();
+    ASSERT_EQ(vm.registerCount(), 0);
+}