fix #364: Fix skipping of if statements evaluated to "false"

Author: adazem009

src/engine/virtualmachine_p.cpp

@@ -238,8 +238,15 @@ unsigned int *VirtualMachinePrivate::run(unsigned int *pos, bool reset)
 
 do_if:
     if (!READ_LAST_REG()->toBool()) {
-        while (*pos != OP_ELSE && *pos != OP_ENDIF)
+        unsigned int ifCounter = 1;
+        while ((*pos != OP_ELSE && *pos != OP_ENDIF) || (ifCounter > 0)) {
             pos += instruction_arg_count[*pos++];
+
+            if (*pos == OP_IF)
+                ifCounter++;
+            else if ((*pos == OP_ELSE) || (*pos == OP_ENDIF))
+                ifCounter--;
+        }
     }
     FREE_REGS(1);
     DISPATCH();

test/virtual_machine/virtual_machine_test.cpp

@@ -1609,10 +1609,20 @@ TEST(VirtualMachineTest, NoCrashWhenRepeatingZeroTimes)
     static unsigned int bytecode[] = { OP_START, OP_CONST, 0, OP_REPEAT_LOOP, OP_UNTIL_LOOP, OP_NULL, OP_BEGIN_UNTIL_LOOP, OP_LOOP_END, OP_LOOP_END, OP_HALT };
     static Value constValues[] = { 0 };
 
-    EngineMock engineMock;
-    VirtualMachine vm(nullptr, &engineMock, nullptr);
+    VirtualMachine vm(nullptr, nullptr, nullptr);
     vm.setBytecode(bytecode);
     vm.setConstValues(constValues);
     vm.run();
     ASSERT_EQ(vm.registerCount(), 0);
 }
+
+TEST(VirtualMachineTest, NoCrashInNestedIfStatementsWithLoop)
+{
+    // Regtest for #364
+    static unsigned int bytecode[] = { OP_START, OP_NULL, OP_IF, OP_NULL, OP_REPEAT_LOOP, OP_NULL, OP_IF, OP_ENDIF, OP_LOOP_END, OP_ENDIF, OP_HALT };
+
+    VirtualMachine vm(nullptr, nullptr, nullptr);
+    vm.setBytecode(bytecode);
+    vm.run();
+    ASSERT_EQ(vm.registerCount(), 0);
+}