org.luaj.vm2.lib.jse.JseBaseLib Java Examples

private LuaEngine() {
	globals = new Globals();
	globals.load(new JseBaseLib());
	globals.load(new PackageLib());
	globals.load(new Bit32Lib());
	globals.load(new TableLib());
	globals.load(new StringLib());
	globals.load(new CoroutineLib());
	globals.load(new JseMathLib());
	globals.load(new JseIoLib());
	globals.load(new JseOsLib());
	globals.load(new MultiDexLuajavaLib());
	LoadState.install(globals);
	LuaC.install(globals);

	globals.finder = this;
	globals.set("loadResource", new resLoader());
}
 

public void init() {
	// Find the script to load from the applet parameters.
	String script = getParameter(script_parameter);
	if (script == null)
		script = default_script;
	System.out.println("Loading " + script);

	// Construct globals specific to the applet platform.
	globals = new Globals();
	globals.load(new JseBaseLib());
	globals.load(new PackageLib());
	globals.load(new Bit32Lib());
	globals.load(new TableLib());
	globals.load(new JseStringLib());
	globals.load(new CoroutineLib());
	globals.load(new JseMathLib());
	globals.load(new JseIoLib());
	globals.load(new JseOsLib());
	globals.load(new AppletLuajavaLib());
	LoadState.install(globals);
	LuaC.install(globals);

	// Use custom resource finder.
	globals.finder = this;

	// Look up and save the handy pcall method.
	pcall = globals.get("pcall");

	// Load and execute the script, supplying this Applet as the only
	// argument.
	globals.loadfile(script).call(CoerceJavaToLua.coerce(this));
}
 

public static void main(String[] args) {
	// Create server globals with just enough library support to compile user scripts.
	server_globals = new Globals();
	server_globals.load(new JseBaseLib());
	server_globals.load(new PackageLib());
	server_globals.load(new JseStringLib());

	// To load scripts, we occasionally need a math library in addition to compiler support.
	// To limit scripts using the debug library, they must be closures, so we only install LuaC.
	server_globals.load(new JseMathLib());
	LoadState.install(server_globals);
	LuaC.install(server_globals);

	// Set up the LuaString metatable to be read-only since it is shared across all scripts.
	LuaString.s_metatable = new ReadOnlyLuaTable(LuaString.s_metatable);

	// Example normal scripts that behave as expected.
	runScriptInSandbox( "return 'foo'" );
	runScriptInSandbox( "return ('abc'):len()" );
	runScriptInSandbox( "return getmetatable('abc')" );
	runScriptInSandbox( "return getmetatable('abc').len" );
	runScriptInSandbox( "return getmetatable('abc').__index" );

	// Example user scripts that attempt rogue operations, and will fail.
	runScriptInSandbox( "return setmetatable('abc', {})" );
	runScriptInSandbox( "getmetatable('abc').len = function() end" );
	runScriptInSandbox( "getmetatable('abc').__index = {}" );
	runScriptInSandbox( "getmetatable('abc').__index.x = 1" );
	runScriptInSandbox( "while true do print('loop') end" );
	
	// Example use of other shared metatables, which should also be made read-only.
	// This toy example allows booleans to be added to numbers.
	runScriptInSandbox( "return 5 + 6, 5 + true, false + 6" );
	LuaBoolean.s_metatable = new ReadOnlyLuaTable(LuaValue.tableOf(new LuaValue[] {
			LuaValue.ADD, new TwoArgFunction() {
				public LuaValue call(LuaValue x, LuaValue y) {
					return LuaValue.valueOf(
							(x == TRUE ? 1.0 : x.todouble()) +
							(y == TRUE ? 1.0 : y.todouble()) );
				}
			},
	}));
	runScriptInSandbox( "return 5 + 6, 5 + true, false + 6" );
}
 

static void runScriptInSandbox(String script) {
	
	// Each script will have it's own set of globals, which should
	// prevent leakage between scripts running on the same server.
	Globals user_globals = new Globals();
	user_globals.load(new JseBaseLib());
	user_globals.load(new PackageLib());
	user_globals.load(new Bit32Lib());
	user_globals.load(new TableLib());
	user_globals.load(new JseStringLib());
	user_globals.load(new JseMathLib());

	// This library is dangerous as it gives unfettered access to the
	// entire Java VM, so it's not suitable within this lightweight sandbox.
	// user_globals.load(new LuajavaLib());
	
	// Starting coroutines in scripts will result in threads that are
	// not under the server control, so this libary should probably remain out.
	// user_globals.load(new CoroutineLib());

	// These are probably unwise and unnecessary for scripts on servers,
	// although some date and time functions may be useful.
	// user_globals.load(new JseIoLib());
	// user_globals.load(new JseOsLib());

	// Loading and compiling scripts from within scripts may also be
	// prohibited, though in theory it should be fairly safe.
	// LoadState.install(user_globals);
	// LuaC.install(user_globals);

	// The debug library must be loaded for hook functions to work, which
	// allow us to limit scripts to run a certain number of instructions at a time.
	// However we don't wish to expose the library in the user globals,
	// so it is immediately removed from the user globals once created.
	user_globals.load(new DebugLib());
	LuaValue sethook = user_globals.get("debug").get("sethook");
	user_globals.set("debug", LuaValue.NIL);

	// Set up the script to run in its own lua thread, which allows us
	// to set a hook function that limits the script to a specific number of cycles.
	// Note that the environment is set to the user globals, even though the
	// compiling is done with the server globals.
	LuaValue chunk = server_globals.load(script, "main", user_globals);
	LuaThread thread = new LuaThread(user_globals, chunk);

	// Set the hook function to immediately throw an Error, which will not be
	// handled by any Lua code other than the coroutine.
	LuaValue hookfunc = new ZeroArgFunction() {
		public LuaValue call() {
			// A simple lua error may be caught by the script, but a
			// Java Error will pass through to top and stop the script.
			throw new Error("Script overran resource limits.");
		}
	};
	final int instruction_count = 20;
	sethook.invoke(LuaValue.varargsOf(new LuaValue[] { thread, hookfunc,
					LuaValue.EMPTYSTRING, LuaValue.valueOf(instruction_count) }));

	// When we resume the thread, it will run up to 'instruction_count' instructions
	// then call the hook function which will error out and stop the script.
	Varargs result = thread.resume(LuaValue.NIL);
	System.out.println("[["+script+"]] -> "+result);
}