electron/lib/renderer/api/remote.js

'use strict';

const ipcRenderer = require('electron').ipcRenderer;
const CallbacksRegistry = require('electron').CallbacksRegistry;
const v8Util = process.atomBinding('v8_util');
const IDWeakMap = process.atomBinding('id_weak_map').IDWeakMap;

const callbacksRegistry = new CallbacksRegistry;

var includes = [].includes;

var remoteObjectCache = new IDWeakMap;

// Check for circular reference.
var isCircular = function(field, visited) {
  if (typeof field === 'object') {
    if (includes.call(visited, field)) {
      return true;
    }
    visited.push(field);
  }
  return false;
};

// Convert the arguments object into an array of meta data.
var wrapArgs = function(args, visited) {
  var valueToMeta;
  if (visited == null) {
    visited = [];
  }
  valueToMeta = function(value) {
    var field, prop, ret;
    if (Array.isArray(value)) {
      return {
        type: 'array',
        value: wrapArgs(value, visited)
      };
    } else if (Buffer.isBuffer(value)) {
      return {
        type: 'buffer',
        value: Array.prototype.slice.call(value, 0)
      };
    } else if (value instanceof Date) {
      return {
        type: 'date',
        value: value.getTime()
      };
    } else if ((value != null ? value.constructor.name : void 0) === 'Promise') {
      return {
        type: 'promise',
        then: valueToMeta(value.then.bind(value))
      };
    } else if ((value != null) && typeof value === 'object' && v8Util.getHiddenValue(value, 'atomId')) {
      return {
        type: 'remote-object',
        id: v8Util.getHiddenValue(value, 'atomId')
      };
    } else if ((value != null) && typeof value === 'object') {
      ret = {
        type: 'object',
        name: value.constructor.name,
        members: []
      };
      for (prop in value) {
        field = value[prop];
        ret.members.push({
          name: prop,
          value: valueToMeta(isCircular(field, visited) ? null : field)
        });
      }
      return ret;
    } else if (typeof value === 'function' && v8Util.getHiddenValue(value, 'returnValue')) {
      return {
        type: 'function-with-return-value',
        value: valueToMeta(value())
      };
    } else if (typeof value === 'function') {
      return {
        type: 'function',
        id: callbacksRegistry.add(value),
        location: v8Util.getHiddenValue(value, 'location')
      };
    } else {
      return {
        type: 'value',
        value: value
      };
    }
  };
  return Array.prototype.slice.call(args).map(valueToMeta);
};

// Populate object's members from descriptors.
// This matches |getObjectMemebers| in rpc-server.
let setObjectMembers = function(object, metaId, members) {
  for (let member of members) {
    if (object.hasOwnProperty(member.name))
      continue;

    let descriptor = { enumerable: member.enumerable };
    if (member.type === 'method') {
      let remoteMemberFunction = function() {
        if (this && this.constructor === remoteMemberFunction) {
          // Constructor call.
          let ret = ipcRenderer.sendSync('ATOM_BROWSER_MEMBER_CONSTRUCTOR', metaId, member.name, wrapArgs(arguments));
          return metaToValue(ret);
        } else {
          // Call member function.
          let ret = ipcRenderer.sendSync('ATOM_BROWSER_MEMBER_CALL', metaId, member.name, wrapArgs(arguments));
          return metaToValue(ret);
        }
      };
      descriptor.writable = true;
      descriptor.configurable = true;
      descriptor.value = remoteMemberFunction;
    } else if (member.type === 'get') {
      descriptor.get = function() {
        return metaToValue(ipcRenderer.sendSync('ATOM_BROWSER_MEMBER_GET', metaId, member.name));
      };

      // Only set setter when it is writable.
      if (member.writable) {
        descriptor.set = function(value) {
          ipcRenderer.sendSync('ATOM_BROWSER_MEMBER_SET', metaId, member.name, value);
          return value;
        };
      }
    }

    Object.defineProperty(object, member.name, descriptor);
  }
};

// Populate object's prototype from descriptor.
// This matches |getObjectPrototype| in rpc-server.
let setObjectPrototype = function(object, metaId, descriptor) {
  if (descriptor === null)
    return;
  let proto = {};
  setObjectMembers(proto, metaId, descriptor.members);
  setObjectPrototype(proto, metaId, descriptor.proto);
  Object.setPrototypeOf(object, proto);
};

// Convert meta data from browser into real value.
let metaToValue = function(meta) {
  var el, i, len, ref1, results, ret;
  switch (meta.type) {
    case 'value':
      return meta.value;
    case 'array':
      ref1 = meta.members;
      results = [];
      for (i = 0, len = ref1.length; i < len; i++) {
        el = ref1[i];
        results.push(metaToValue(el));
      }
      return results;
    case 'buffer':
      return new Buffer(meta.value);
    case 'promise':
      return Promise.resolve({
        then: metaToValue(meta.then)
      });
    case 'error':
      return metaToPlainObject(meta);
    case 'date':
      return new Date(meta.value);
    case 'exception':
      throw new Error(meta.message + "\n" + meta.stack);
    default:
      if (remoteObjectCache.has(meta.id))
        return remoteObjectCache.get(meta.id);

      if (meta.type === 'function') {
        // A shadow class to represent the remote function object.
        let remoteFunction = function() {
          if (this && this.constructor === remoteFunction) {
            // Constructor call.
            let obj = ipcRenderer.sendSync('ATOM_BROWSER_CONSTRUCTOR', meta.id, wrapArgs(arguments));
            // Returning object in constructor will replace constructed object
            // with the returned object.
            // http://stackoverflow.com/questions/1978049/what-values-can-a-constructor-return-to-avoid-returning-this
            return metaToValue(obj);
          } else {
            // Function call.
            let obj = ipcRenderer.sendSync('ATOM_BROWSER_FUNCTION_CALL', meta.id, wrapArgs(arguments));
            return metaToValue(obj);
          }
        };
        ret = remoteFunction;
      } else {
        ret = {};
      }

      // Populate delegate members.
      setObjectMembers(ret, meta.id, meta.members);
      // Populate delegate prototype.
      setObjectPrototype(ret, meta.id, meta.proto);

      // Set constructor.name to object's name.
      Object.defineProperty(ret.constructor, 'name', { value: meta.name });

      // Track delegate object's life time, and tell the browser to clean up
      // when the object is GCed.
      v8Util.setDestructor(ret, function() {
        ipcRenderer.send('ATOM_BROWSER_DEREFERENCE', meta.id);
      });

      // Remember object's id.
      v8Util.setHiddenValue(ret, 'atomId', meta.id);
      remoteObjectCache.set(meta.id, ret);
      return ret;
  }
};

// Construct a plain object from the meta.
var metaToPlainObject = function(meta) {
  var i, len, name, obj, ref1, ref2, value;
  obj = (function() {
    switch (meta.type) {
      case 'error':
        return new Error;
      default:
        return {};
    }
  })();
  ref1 = meta.members;
  for (i = 0, len = ref1.length; i < len; i++) {
    ref2 = ref1[i], name = ref2.name, value = ref2.value;
    obj[name] = value;
  }
  return obj;
};

// Browser calls a callback in renderer.
ipcRenderer.on('ATOM_RENDERER_CALLBACK', function(event, id, args) {
  return callbacksRegistry.apply(id, metaToValue(args));
});

// A callback in browser is released.
ipcRenderer.on('ATOM_RENDERER_RELEASE_CALLBACK', function(event, id) {
  return callbacksRegistry.remove(id);
});

// List all built-in modules in browser process.
const browserModules = require('../../../browser/api/lib/exports/electron');

// And add a helper receiver for each one.
var fn = function(name) {
  return Object.defineProperty(exports, name, {
    get: function() {
      return exports.getBuiltin(name);
    }
  });
};
for (var name in browserModules) {
  fn(name);
}

// Get remote module.
exports.require = function(module) {
  return metaToValue(ipcRenderer.sendSync('ATOM_BROWSER_REQUIRE', module));
};

// Alias to remote.require('electron').xxx.
exports.getBuiltin = function(module) {
  return metaToValue(ipcRenderer.sendSync('ATOM_BROWSER_GET_BUILTIN', module));
};

// Get current BrowserWindow.
exports.getCurrentWindow = function() {
  return metaToValue(ipcRenderer.sendSync('ATOM_BROWSER_CURRENT_WINDOW'));
};

// Get current WebContents object.
exports.getCurrentWebContents = function() {
  return metaToValue(ipcRenderer.sendSync('ATOM_BROWSER_CURRENT_WEB_CONTENTS'));
};

// Get a global object in browser.
exports.getGlobal = function(name) {
  return metaToValue(ipcRenderer.sendSync('ATOM_BROWSER_GLOBAL', name));
};

// Get the process object in browser.
exports.__defineGetter__('process', function() {
  return exports.getGlobal('process');
});

// Create a funtion that will return the specifed value when called in browser.
exports.createFunctionWithReturnValue = function(returnValue) {
  var func;
  func = function() {
    return returnValue;
  };
  v8Util.setHiddenValue(func, 'returnValue', true);
  return func;
};

// Get the guest WebContents from guestInstanceId.
exports.getGuestWebContents = function(guestInstanceId) {
  var meta;
  meta = ipcRenderer.sendSync('ATOM_BROWSER_GUEST_WEB_CONTENTS', guestInstanceId);
  return metaToValue(meta);
};