lua: add SCFlowHasAlerts function

Add SCFlowHasAlerts() to check if a flow has alerts. Returns true
on alerts, false otherwise.

Example:

  has_alerts = SCFlowHasAlerts()
  if has_alerts then
    -- do something
  end

src/util-lua-common.c

@@ -247,6 +247,37 @@ static int LuaCallbackFlowTimeString(lua_State *luastate)
     return r;
 }
 
+/** \internal
+ *  \brief fill lua stack with flow has alerts
+ *  \param luastate the lua state
+ *  \param flow flow
+ *  \retval cnt number of data items placed on the stack
+ *
+ *  Places alerts (bool)
+ */
+static int LuaCallbackHasAlertsPushToStackFromFlow(lua_State *luastate, const Flow *flow)
+{
+    lua_pushboolean(luastate, FlowHasAlerts(flow));
+
+    return 1;
+}
+
+/** \internal
+ *  \brief Wrapper for getting flow has alerts info into a lua script
+ *  \retval cnt number of items placed on the stack
+ */
+static int LuaCallbackFlowHasAlerts(lua_State *luastate)
+{
+    int r = 0;
+    Flow *flow = LuaStateGetFlow(luastate);
+    if (flow == NULL)
+        return LuaCallbackError(luastate, "internal error: no flow");
+
+    r = LuaCallbackHasAlertsPushToStackFromFlow(luastate, flow);
+
+    return r;
+}
+
 /** \internal
  *  \brief fill lua stack with header info
  *  \param luastate the lua state
@@ -768,6 +799,8 @@ int LuaRegisterFunctions(lua_State *luastate)
     lua_setglobal(luastate, "SCFlowAppLayerProto");
     lua_pushcfunction(luastate, LuaCallbackStatsFlow);
     lua_setglobal(luastate, "SCFlowStats");
+    lua_pushcfunction(luastate, LuaCallbackFlowHasAlerts);
+    lua_setglobal(luastate, "SCFlowHasAlerts");
 
     lua_pushcfunction(luastate, LuaCallbackStreamingBuffer);
     lua_setglobal(luastate, "SCStreamingBuffer");