GM 2 port - Function Override Helper

Not yet.

Script này sẽ không được không được cài đặt trực tiếp. Nó là một thư viện cho các script khác để bao gồm các chỉ thị meta // @require https://update.greasyfork.org/scripts/2599/184155/GM%202%20port%20-%20Function%20Override%20Helper.js

// ==UserScript==
// @name        GM 2 port - Function Override Helper
// @Description Not yet.
// @namespace   org.jixun.gm2.port
// @version     1.0.4

// unsafeWindow required to use `exportFunction`.
// @grant       unsafeWindow

// @run-at      document-start
// ==/UserScript==

// Check if is GM 2.x
if (typeof exportFunction == 'undefined') {
	// For GM 1.x backward compatibility, should work.
	var exportFunction = (function (foo, scope, defAs) {
		if (defAs && defAs.defineAs) {
			scope[defAs.defineAs] = foo;
		}
		return foo;
	}).bind(unsafeWindow);

	// Well.. It's not going to do anything.
	var cloneInto = (function (obj, scope, opt) {
		return obj;
	}).bind(unsafeWindow);
}

/**
 * unsafeObject:
 * Basically cloneInto but could without scope (Default: unsafeWindow)
 * 
 * @param  {Object} obj   Object to pass through
 * @param  {Object} scope Scope where object is going to be applied.
 * @param  {Object} opt   Options
 * @return {Object}       A reference to the cloned object.
 */
var unsafeObject = function (obj, scope, opt) {
	return cloneInto (obj, scope || unsafeWindow, opt || {});
};

/**
 * unsafeDefineFunction
 * @param  {String} fooName Target name
 * @param  {Function} foo   The function to override
 * @param  {Object} scope   unsafeWindow
 * @return {Function}       The placeholder function which has been created in the target context.
 */
var unsafeDefineFunction = function (fooName, foo, scope) {
	// @throw TypeError: can't redefine non-configurable property
	// @throw Error: First argument must be a function
	return exportFunction (foo, scope || unsafeWindow, {defineAs: fooName});
};

/**
 * unsafeOverwriteFunction
 * @param  {Object} fooMapping {name: foo}
 * @param  {Object} scope      unsafeWindow
 * @param  {String} scopeName  Optional, required if target is not `window`.
 *                             e.g. The target is window.api.xxx, '.api' would
 *                             be the scopeName.
 * @return {HTML Element}      Script Tag
 */
var unsafeOverwriteFunction = function (fooMapping, scope, scopeName) {
	var argMapping = {}, tmpName;

	// Mapping new random names.
	for (var x in fooMapping) {
		if (fooMapping.hasOwnProperty(x)) {
			try {
				tmpName = 'u_w_f_' + Math.random().toString().slice(2) + +new Date();
				
				// Export function
				// unsafeDefineFunction will take care of null values.
				unsafeDefineFunction (tmpName, fooMapping[x], scope);
				argMapping[x] = tmpName;
			} catch (e) {
				console.error ('Error at `unsafeOverwrite`:', e);
			}
		}
	}

	var tmpScript = document.createElement ('script');
	tmpScript.textContent = ';('+ (function (j, x) {
		for (x in j)
			if (j.hasOwnProperty(x))
				// Map everything.
				// If Object with custom function / Function 
				// passed in it will throw CloneNonReflectorsWrite.
				// Use unsafeOverwriteFunctionSafeProxy if you need to bypass that.
				// However, it's going to be slower.
				window/**/[x] = window/**/[j[x]];
		
		// TODO: Maybe remove this script tag after finish?
	}).toString().replace(/\/\*\*\//g, scopeName ? scopeName : '') +')(' + JSON.stringify(argMapping) + ');';
	document.head.appendChild (tmpScript);

	return tmpScript;
};

/**
 * ErrorUnsafe:
 * An error class for unsafeOverwriteFunctionSafeProxy.
 * 
 * @param {String} name    Error Name
 * @param {String} message Error Message
 */
var ErrorUnsafe = function (name, message) {
	return cloneInto ({
		name: name || 'ErrorUnsafe',
		message: message || 'Unknown error.'
	}, scope || unsafeWindow);
};

/**
 * ErrorUnsafeSuccess:
 * An Error Class for unsafeOverwriteFunctionSafeProxy.
 * Inform proxy to execute origional function with its full arguments.
 * 
 * @param {[type]} message [description]
 * @param {[type]} scope   [description]
 */
var ErrorUnsafeSuccess = function (message, scope) {
	return cloneInto ({
		name: 'ErrorUnsafeSuccess: ProxyFinish',
		success: true,
		message: message || ''
	}, scope || unsafeWindow);
};

/**
 * unsafeOverwriteFunctionSafeProxy
 * Similar to unsafeOverwriteFunction, but its a proxy instead.
 * It will strip all functions before pass in to sandboxed function.
 * So, it can prevent CloneNonReflectorsWrite error.
 * 
 * @param  {[type]} fooMapping [description]
 * @param  {[type]} scope      [description]
 * @param  {[type]} scopeName  [description]
 * @return {[type]}            [description]
 */
var unsafeOverwriteFunctionSafeProxy = function (fooMapping, scope, scopeName) {
	var argMapping = {}, tmpName;

	// Mapping new random names.
	for (var x in fooMapping) {
		if (fooMapping.hasOwnProperty(x)) {
			try {
				tmpName = 'u_w_f_' + Math.random().toString().slice(2) + +new Date();
				
				// Export function
				// unsafeDefineFunction will take care of null values.
				unsafeDefineFunction (tmpName, fooMapping[x], scope);
				argMapping[x] = tmpName;
			} catch (e) {
				console.error ('Error at `unsafeOverwrite`:', e);
				alert (e);
			}
		}
	}

	var tmpScript = document.createElement ('script');
	tmpScript.textContent = ';('+ (function (j, x) {
		for (x in j)
			if (j.hasOwnProperty(x)) {
				(function (x, bak, foo) {
					// Assign variable to our proxy function.
					window/**/[x] = function () {
						// console.info (arguments);
						for (var i = 0, y, args = []; i < arguments.length; i++) {
							// Array - Sure we can handle this right?
							if (arguments[i] instanceof Array) {
								args.push (arguments[i].slice());
							} else if (arguments[i] instanceof Object) {
								// Strip off all prototype functions, if possible.
								
								// TODO: maybe try-catch the following line?
								args.push (JSON.parse(JSON.stringify (arguments[i])));
							} else if ('function' == typeof arguments[i]) {
								// Function can't be sandboxied :<
								args.push (null);
							} else {
								// idk... should be safe to pass through?
								args.push (arguments[i]);
							}
						}

						try {
							// Try to call our function!
							return foo.apply(this, args);
						} catch (err) {
							// We throw this error on purpose,
							// if we need to do the complete callback.
							
							// If the error don'e have success flag, we'll 
							// throw the error to console.

							if (!err.success) console.error (err);
							return bak.apply (this, arguments);
						}
					};
				}) (x, window/**/[x], window/**/[j[x]]);
			}

		// TODO: Maybe remove this script tag after finish?
	}).toString().replace(/\/\*\*\//g, scopeName ? scopeName : '') +')(' + JSON.stringify(argMapping) + ');';
	document.head.appendChild (tmpScript);

	return tmpScript;
};

/**
 * Execute function anonymously
 * @param  {Function} foo
 * @param  {Any} Any arguments to be passed in.
 * @return {ScriptNode}
 */
var unsafeExec = function (foo) {
	var tmpScript = document.createElement ('script');

	// Now supports arguments!
	tmpScript.textContent =
		';(' + foo + ').apply (null, ' +
			JSON.stringify([].slice.call(arguments, 1)) + ');';

	document.head.appendChild (tmpScript);
	return tmpScript;
};