Question

嗨，大家好！我有一个嵌入Lua的C ++应用程序作为脚本。非程序员编辑Lua脚本，然后C ++应用程序调用Lua脚本，Lua脚本也调用C ++注册函数。

我使用Luaplus完成上述工作。我的问题是：当脚本编辑器出错（如拼写错误参数）时，C ++应用程序崩溃了！我该怎么做才能防止这种情况发生？感谢

Answer 1

看看lua_cpcall和lua_pcall。它们都允许在c中保护lua的函数。如果它们返回非负数，则调用失败，并且lua堆栈仅包含错误字符串。在cpcalls的情况下，堆栈是未修改的。对于pcall，您需要查看lua_pushcclosure以安全地调用cfunction。

你要做的是：用你想要的所有lua_ *调用创建一个c函数，比如loadfile和dofile。您可以使用lua_cpcall或lua_pushcclosure amd lua_pcall调用此函数。这允许您检测t中是否发生错误他的功能你传递给了cpcall。

示例：

function hello() {
  string hello_ = "Hello Lua!";
  struct C {
    static int call(lua_State* L) {
      C *p = static_cast<C*>(lua_touserdata(L,-1));
      lua_pushstring(L, p->str.c_str() );
      lua_getglobal(L, "print"); 
      lua_call(L, 1, 0); //ok
      lua_pushstring(L, p->str.c_str() );
      lua_getglobal(L, "notprint"); 
      lua_call(L, 1, 0); //error -> longjmps
      return 0; //Number of values on stack to 'return' to lua
    }
    const string& str;
  } p = { hello_ };
  //protected call of C::call() above
  //with &p as 1st/only element on Lua stack
  //any errors encountered will trigger a longjmp out of lua and
  //return a non-0 error code and a string on the stack
  //A return of 0 indicates success and the stack is unmodified
  //to invoke LUA functions safely use the lua_pcall function
  int res = lua_cpcall(L, &C::call, &p);
  if( res ) {
    string err = lua_tostring(L, -1);
    lua_pop(L, 1);
    //Error hanlder here
  }
  //load a .lua file
  if( (res=luaL_loadfile(L, "myLuaFile.lua")) ) {
    string err = lua_tostring(L, -1);
    lua_pop(L, 1);
    //res is one of
    //LUA_ERRSYNTAX - Lua syntax error
    //LUA_ERRMEM    - Out of memory error
    //LUE_ERRFILE   - File not found/accessible error
  }
  //execute it
  if( (res=lua_pcall(L,0,0,0)) ) {
    string err = lua_tostring(L, -1);
    lua_pop(L, 1);
    // res is one of
    // LUA_ERRRUN: a runtime error.
    // LUA_ERRMEM: memory allocation error.
    // LUA_ERRERR: error while running the error handler function (NULL in this case).
  }
  // try to call [a_int,b_str] = Foo(1,2,"3")
  lua_getglobal(L,"Foo");
  if( lua_isfunction(L,lua_gettop(L)) ) { //Foo exists
    lua_pushnumber(L,1);
    lua_pushnumber(L,2);
    lua_pushstring(L,"3");
    lua_pushvalue(L, -4); //copy of foo()

    if( (res = lua_pcall(L, 3, 2, 0/*default error func*/)) ) {
      string err = lua_tostring(L, -1);
      lua_pop(L, 1);
      //error: see above
    }
    int a_int = (int)lua_tointeger(L,-2);
    string b_str = lua_tostring(L,-1);
    lua_pop(L,2+1); //2 returns, + extra copy of Foo()
  }
}

Safe Lua调用C ++注册函数

1 个答案: