Max Dashouk | ba5c3fd | 2021-05-06 11:50:02 -0700 | [diff] [blame] | 1 | /* |
Zhomart Mukhamejanov | 4efd36d | 2021-04-19 14:22:59 -0700 | [diff] [blame] | 2 | * Copyright (c) 2021, The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
Max Dashouk | ba5c3fd | 2021-05-06 11:50:02 -0700 | [diff] [blame] | 17 | #include "LuaEngine.h" |
| 18 | |
| 19 | #include <utility> |
| 20 | |
| 21 | extern "C" { |
| 22 | #include "lauxlib.h" |
| 23 | #include "lualib.h" |
| 24 | } |
Zhomart Mukhamejanov | 4efd36d | 2021-04-19 14:22:59 -0700 | [diff] [blame] | 25 | |
| 26 | namespace android { |
| 27 | namespace automotive { |
| 28 | namespace telemetry { |
Max Dashouk | ba5c3fd | 2021-05-06 11:50:02 -0700 | [diff] [blame] | 29 | namespace script_executor { |
Zhomart Mukhamejanov | 4efd36d | 2021-04-19 14:22:59 -0700 | [diff] [blame] | 30 | |
Max Dashouk | e864dfc | 2021-05-20 14:19:32 -0700 | [diff] [blame] | 31 | LuaEngine::LuaEngine() { |
Max Dashouk | 2c013db | 2021-06-30 17:43:54 +0000 | [diff] [blame] | 32 | // Instantiate Lua environment |
Max Dashouk | ba5c3fd | 2021-05-06 11:50:02 -0700 | [diff] [blame] | 33 | mLuaState = luaL_newstate(); |
| 34 | luaL_openlibs(mLuaState); |
Zhomart Mukhamejanov | 4efd36d | 2021-04-19 14:22:59 -0700 | [diff] [blame] | 35 | } |
| 36 | |
Max Dashouk | ba5c3fd | 2021-05-06 11:50:02 -0700 | [diff] [blame] | 37 | LuaEngine::~LuaEngine() { |
| 38 | lua_close(mLuaState); |
Zhomart Mukhamejanov | 4efd36d | 2021-04-19 14:22:59 -0700 | [diff] [blame] | 39 | } |
| 40 | |
Max Dashouk | e864dfc | 2021-05-20 14:19:32 -0700 | [diff] [blame] | 41 | lua_State* LuaEngine::GetLuaState() { |
| 42 | return mLuaState; |
| 43 | } |
| 44 | |
Max Dashouk | 2c013db | 2021-06-30 17:43:54 +0000 | [diff] [blame] | 45 | void LuaEngine::ResetListener(ScriptExecutorListener* listener) { |
| 46 | mListener.reset(listener); |
| 47 | } |
| 48 | |
| 49 | int LuaEngine::LoadScript(const char* scriptBody) { |
| 50 | // As the first step in Lua script execution we want to load |
| 51 | // the body of the script into Lua stack and have it processed by Lua |
| 52 | // to catch any errors. |
| 53 | // More on luaL_dostring: https://www.lua.org/manual/5.3/manual.html#lual_dostring |
| 54 | // If error, pushes the error object into the stack. |
| 55 | const auto status = luaL_dostring(mLuaState, scriptBody); |
| 56 | if (status) { |
| 57 | // Removes error object from the stack. |
| 58 | // Lua stack must be properly maintained due to its limited size, |
| 59 | // ~20 elements and its critical function because all interaction with |
| 60 | // Lua happens via the stack. |
| 61 | // Starting read about Lua stack: https://www.lua.org/pil/24.2.html |
| 62 | // TODO(b/192284232): add test case to trigger this. |
| 63 | lua_pop(mLuaState, 1); |
| 64 | } |
| 65 | return status; |
| 66 | } |
| 67 | |
| 68 | bool LuaEngine::PushFunction(const char* functionName) { |
| 69 | // Interaction between native code and Lua happens via Lua stack. |
| 70 | // In such model, a caller first pushes the name of the function |
| 71 | // that needs to be called, followed by the function's input |
| 72 | // arguments, one input value pushed at a time. |
| 73 | // More info: https://www.lua.org/pil/24.2.html |
| 74 | lua_getglobal(mLuaState, functionName); |
| 75 | const auto status = lua_isfunction(mLuaState, /*idx= */ -1); |
| 76 | // TODO(b/192284785): add test case for wrong function name in Lua. |
| 77 | if (status == 0) lua_pop(mLuaState, 1); |
| 78 | return status; |
| 79 | } |
| 80 | |
| 81 | int LuaEngine::Run() { |
| 82 | // Performs blocking call of the provided Lua function. Assumes all |
| 83 | // input arguments are in the Lua stack as well in proper order. |
| 84 | // On how to call Lua functions: https://www.lua.org/pil/25.2.html |
| 85 | // Doc on lua_pcall: https://www.lua.org/manual/5.3/manual.html#lua_pcall |
| 86 | // TODO(b/189241508): Once we implement publishedData parsing, nargs should |
| 87 | // change from 1 to 2. |
| 88 | // TODO(b/192284612): add test case for failed call. |
| 89 | return lua_pcall(mLuaState, /* nargs= */ 1, /* nresults= */ 0, /*errfunc= */ 0); |
| 90 | } |
| 91 | |
Max Dashouk | ba5c3fd | 2021-05-06 11:50:02 -0700 | [diff] [blame] | 92 | } // namespace script_executor |
Zhomart Mukhamejanov | 4efd36d | 2021-04-19 14:22:59 -0700 | [diff] [blame] | 93 | } // namespace telemetry |
| 94 | } // namespace automotive |
| 95 | } // namespace android |