fix(lua): better print function, and override require

core/src/objects/script.cpp

@@ -39,6 +39,9 @@ Script::~Script() {
 void Script::Run() {
     lua_State* L = dataModel().value()->GetService<ScriptContext>()->state;
 
+    // Initialize script globals
+    
+
     luaL_loadstring(L, source.c_str());
     int status = lua_pcall(L, 0, LUA_MULTRET, 0);
     if (status != 0) {

core/src/objects/script/scriptcontext.cpp

@@ -4,12 +4,18 @@
 #include <luajit-2.1/lua.h>
 #include <luajit-2.1/lualib.h>
 
-static int redirectPrint(lua_State*);
+static int g_print(lua_State*);
+static int g_require(lua_State*);
 static const struct luaL_Reg luaglobals [] = {
-    {"print", redirectPrint},
+    {"print", g_print},
+    {"require", g_require},
     {NULL, NULL} /* end of array */
 };
 
+std::string unsafe_globals[] = {
+    "loadfile", "loadstring", "load", "dofile", "getfenv", "setfenv"
+};
+
 const InstanceType ScriptContext::TYPE = {
     .super = &Instance::TYPE,
     .className = "ScriptContext",
@@ -34,28 +40,62 @@ void ScriptContext::InitService() {
     initialized = true;
 
     state = luaL_newstate();
-    luaL_openlibs(state);
+    luaopen_base(state);
+    luaopen_math(state);
+    luaopen_string(state);
+    luaopen_table(state);
+    // luaopen_io(state);
+    // luaopen_os(state);
+    // luaopen_package(state);
+    // luaopen_debug(state);
+    luaopen_bit(state);
+
+    // TODO: custom os library
 
     // Override print
     // https://stackoverflow.com/a/4514193/16255372
     
     lua_getglobal(state, "_G");
     luaL_register(state, NULL, luaglobals);
+
+    // Remove misc dangerous functions
+    for (std::string key : unsafe_globals) {
+        lua_pushstring(state, key.c_str());
+        lua_pushnil(state);
+        lua_rawset(state, -3);
+    }
+
     lua_pop(state, 1);
+
 }
 
-static int redirectPrint(lua_State* L) {
+// https://www.lua.org/source/5.1/lbaselib.c.html
+static int g_print(lua_State* L) {
     std::string buf;
 
     int nargs = lua_gettop(L);
 
+    lua_getglobal(L, "tostring");
     for (int i=1; i <= nargs; i++) {
-        std::string arg(lua_tostring(L, -1));
+        lua_pushvalue(L, -1); // push tostring
-        lua_pop(L, 1);
+        lua_pushvalue(L, i); // push current arg
-        buf += arg;
+        lua_call(L, 1, 1); // call tostring with current arg (#1 arguments)
+        // lua_call automatically pops function and arguments
+
+        const char* str = lua_tostring(L, -1); // convert result into c-string
+        lua_pop(L, 1); // pop result
+        
+        buf += str;
     }
 
-    Logger::infof(buf);
+    Logger::info(buf);
 
     return 0;
+}
+
+static int g_require(lua_State* L) {
+    int nargs = lua_gettop(L);
+    if (nargs < 1) return luaL_error(L, "expected argument module");
+
+    return luaL_error(L, "require is not yet implemented");
 }