src/legacy-exec/ios/exec.js - cordova-js - Git at Google

 /*
  *
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  *
 */

 /**
  * Creates a gap bridge iframe used to notify the native code about queued
  * commands.
  */
 var cordova = require('cordova'),
     channel = require('cordova/channel'),
     utils = require('cordova/utils'),
     base64 = require('cordova/base64'),
     // XHR mode does not work on iOS 4.2.
     // XHR mode's main advantage is working around a bug in -webkit-scroll, which
     // doesn't exist only on iOS 5.x devices.
     // IFRAME_NAV is the fastest.
     // IFRAME_HASH could be made to enable synchronous bridge calls if we wanted this feature.
     jsToNativeModes = {
         IFRAME_NAV: 0, // Default. Uses a new iframe for each poke.
         // XHR bridge appears to be flaky sometimes: CB-3900, CB-3359, CB-5457, CB-4970, CB-4998, CB-5134
         XHR_NO_PAYLOAD: 1, // About the same speed as IFRAME_NAV. Performance not about the same as IFRAME_NAV, but more variable.
         XHR_WITH_PAYLOAD: 2, // Flakey, and not as performant
         XHR_OPTIONAL_PAYLOAD: 3, // Flakey, and not as performant
         IFRAME_HASH_NO_PAYLOAD: 4, // Not fully baked. A bit faster than IFRAME_NAV, but risks jank since poke happens synchronously.
         IFRAME_HASH_WITH_PAYLOAD: 5, // Slower than no payload. Maybe since it has to be URI encoded / decoded.
         WK_WEBVIEW_BINDING: 6 // Only way that works for WKWebView :)
     },
     bridgeMode,
     execIframe,
     execHashIframe,
     hashToggle = 1,
     execXhr,
     requestCount = 0,
     vcHeaderValue = null,
     commandQueue = [], // Contains pending JS->Native messages.
     isInContextOfEvalJs = 0,
     failSafeTimerId = 0;

 function shouldBundleCommandJson() {
     if (bridgeMode === jsToNativeModes.XHR_WITH_PAYLOAD) {
         return true;
     }
     if (bridgeMode === jsToNativeModes.XHR_OPTIONAL_PAYLOAD) {
         var payloadLength = 0;
         for (var i = 0; i < commandQueue.length; ++i) {
             payloadLength += commandQueue[i].length;
         }
         // The value here was determined using the benchmark within CordovaLibApp on an iPad 3.
         return payloadLength < 4500;
     }
     return false;
 }

 function massageArgsJsToNative(args) {
     if (!args || utils.typeName(args) != 'Array') {
         return args;
     }
     var ret = [];
     args.forEach(function(arg, i) {
         if (utils.typeName(arg) == 'ArrayBuffer') {
             ret.push({
                 'CDVType': 'ArrayBuffer',
                 'data': base64.fromArrayBuffer(arg)
             });
         } else {
             ret.push(arg);
         }
     });
     return ret;
 }

 function massageMessageNativeToJs(message) {
     if (message.CDVType == 'ArrayBuffer') {
         var stringToArrayBuffer = function(str) {
             var ret = new Uint8Array(str.length);
             for (var i = 0; i < str.length; i++) {
                 ret[i] = str.charCodeAt(i);
             }
             return ret.buffer;
         };
         var base64ToArrayBuffer = function(b64) {
             return stringToArrayBuffer(atob(b64));
         };
         message = base64ToArrayBuffer(message.data);
     }
     return message;
 }

 function convertMessageToArgsNativeToJs(message) {
     var args = [];
     if (!message || !message.hasOwnProperty('CDVType')) {
         args.push(message);
     } else if (message.CDVType == 'MultiPart') {
         message.messages.forEach(function(e) {
             args.push(massageMessageNativeToJs(e));
         });
     } else {
         args.push(massageMessageNativeToJs(message));
     }
     return args;
 }

 function iOSExec() {
     if (bridgeMode === undefined) {
         bridgeMode = jsToNativeModes.IFRAME_NAV;
     }

     if (window.webkit && window.webkit.messageHandlers && window.webkit.messageHandlers.cordova && window.webkit.messageHandlers.cordova.postMessage) {
         bridgeMode = jsToNativeModes.WK_WEBVIEW_BINDING;
     }

     var successCallback, failCallback, service, action, actionArgs, splitCommand;
     var callbackId = null;
     if (typeof arguments[0] !== "string") {
         // FORMAT ONE
         successCallback = arguments[0];
         failCallback = arguments[1];
         service = arguments[2];
         action = arguments[3];
         actionArgs = arguments[4];

         // Since we need to maintain backwards compatibility, we have to pass
         // an invalid callbackId even if no callback was provided since plugins
         // will be expecting it. The Cordova.exec() implementation allocates
         // an invalid callbackId and passes it even if no callbacks were given.
         callbackId = 'INVALID';
     } else {
         // FORMAT TWO, REMOVED
         try {
             splitCommand = arguments[0].split(".");
             action = splitCommand.pop();
             service = splitCommand.join(".");
             actionArgs = Array.prototype.splice.call(arguments, 1);

             console.log('The old format of this exec call has been removed (deprecated since 2.1). Change to: ' +
                        "cordova.exec(null, null, \"" + service + "\", \"" + action + "\"," + JSON.stringify(actionArgs) + ");"
             );
             return;
         } catch (e) {}
     }

     // If actionArgs is not provided, default to an empty array
     actionArgs = actionArgs || [];

     // Register the callbacks and add the callbackId to the positional
     // arguments if given.
     if (successCallback || failCallback) {
         callbackId = service + cordova.callbackId++;
         cordova.callbacks[callbackId] =
             {success:successCallback, fail:failCallback};
     }

     actionArgs = massageArgsJsToNative(actionArgs);

     var command = [callbackId, service, action, actionArgs];

     if (bridgeMode === jsToNativeModes.WK_WEBVIEW_BINDING) {
         window.webkit.messageHandlers.cordova.postMessage(command);
     } else {
         // Stringify and queue the command. We stringify to command now to
         // effectively clone the command arguments in case they are mutated before
         // the command is executed.
         commandQueue.push(JSON.stringify(command));

         // If we're in the context of a stringByEvaluatingJavaScriptFromString call,
         // then the queue will be flushed when it returns; no need for a poke.
         // Also, if there is already a command in the queue, then we've already
         // poked the native side, so there is no reason to do so again.
         if (!isInContextOfEvalJs && commandQueue.length == 1) {
             pokeNative();
         }
     }
 }

 function pokeNative() {
     switch (bridgeMode) {
     case jsToNativeModes.XHR_NO_PAYLOAD:
     case jsToNativeModes.XHR_WITH_PAYLOAD:
     case jsToNativeModes.XHR_OPTIONAL_PAYLOAD:
         pokeNativeViaXhr();
         break;
     default: // iframe-based.
         pokeNativeViaIframe();
     }
 }

 function pokeNativeViaXhr() {
     // This prevents sending an XHR when there is already one being sent.
     // This should happen only in rare circumstances (refer to unit tests).
     if (execXhr && execXhr.readyState != 4) {
         execXhr = null;
     }
     // Re-using the XHR improves exec() performance by about 10%.
     execXhr = execXhr || new XMLHttpRequest();
     // Changing this to a GET will make the XHR reach the URIProtocol on 4.2.
     // For some reason it still doesn't work though...
     // Add a timestamp to the query param to prevent caching.
     execXhr.open('HEAD', "/!gap_exec?" + (+new Date()), true);
     if (!vcHeaderValue) {
         vcHeaderValue = /.*\((.*)\)$/.exec(navigator.userAgent)[1];
     }
     execXhr.setRequestHeader('vc', vcHeaderValue);
     execXhr.setRequestHeader('rc', ++requestCount);
     if (shouldBundleCommandJson()) {
         execXhr.setRequestHeader('cmds', iOSExec.nativeFetchMessages());
     }
     execXhr.send(null);
 }

 function pokeNativeViaIframe() {
     // CB-5488 - Don't attempt to create iframe before document.body is available.
     if (!document.body) {
         setTimeout(pokeNativeViaIframe);
         return;
     }
     if (bridgeMode === jsToNativeModes.IFRAME_HASH_NO_PAYLOAD || bridgeMode === jsToNativeModes.IFRAME_HASH_WITH_PAYLOAD) {
         // TODO: This bridge mode doesn't properly support being removed from the DOM (CB-7735)
         if (!execHashIframe) {
             execHashIframe = document.createElement('iframe');
             execHashIframe.style.display = 'none';
             document.body.appendChild(execHashIframe);
             // Hash changes don't work on about:blank, so switch it to file:///.
             execHashIframe.contentWindow.history.replaceState(null, null, 'file:///#');
         }
         // The delegate method is called only when the hash changes, so toggle it back and forth.
         hashToggle = hashToggle ^ 3;
         var hashValue = '%0' + hashToggle;
         if (bridgeMode === jsToNativeModes.IFRAME_HASH_WITH_PAYLOAD) {
             hashValue += iOSExec.nativeFetchMessages();
         }
         execHashIframe.contentWindow.location.hash = hashValue;
     } else {
         // Check if they've removed it from the DOM, and put it back if so.
         if (execIframe && execIframe.contentWindow) {
             execIframe.contentWindow.location = 'gap://ready';
         } else {
             execIframe = document.createElement('iframe');
             execIframe.style.display = 'none';
             execIframe.src = 'gap://ready';
             document.body.appendChild(execIframe);
         }
         // Use a timer to protect against iframe being unloaded during the poke (CB-7735).
         // This makes the bridge ~ 7% slower, but works around the poke getting lost
         // when the iframe is removed from the DOM.
         // An onunload listener could be used in the case where the iframe has just been
         // created, but since unload events fire only once, it doesn't work in the normal
         // case of iframe reuse (where unload will have already fired due to the attempted
         // navigation of the page).
         failSafeTimerId = setTimeout(function() {
             if (commandQueue.length) {
                 pokeNative();
             }
         }, 50); // Making this > 0 improves performance (marginally) in the normal case (where it doesn't fire).
     }
 }

 iOSExec.jsToNativeModes = jsToNativeModes;

 iOSExec.setJsToNativeBridgeMode = function(mode) {
     // Remove the iFrame since it may be no longer required, and its existence
     // can trigger browser bugs.
     // https://issues.apache.org/jira/browse/CB-593
     if (execIframe) {
         if (execIframe.parentNode) {
             execIframe.parentNode.removeChild(execIframe);
         }
         execIframe = null;
     }
     bridgeMode = mode;
 };

 iOSExec.nativeFetchMessages = function() {
     // Stop listing for window detatch once native side confirms poke.
     if (failSafeTimerId) {
         clearTimeout(failSafeTimerId);
         failSafeTimerId = 0;
     }
     // Each entry in commandQueue is a JSON string already.
     if (!commandQueue.length) {
         return '';
     }
     var json = '[' + commandQueue.join(',') + ']';
     commandQueue.length = 0;
     return json;
 };

 iOSExec.nativeCallback = function(callbackId, status, message, keepCallback) {
     return iOSExec.nativeEvalAndFetch(function() {
         var success = status === 0 || status === 1;
         var args = convertMessageToArgsNativeToJs(message);
         cordova.callbackFromNative(callbackId, success, status, args, keepCallback);
     });
 };

 iOSExec.nativeEvalAndFetch = function(func) {
     // This shouldn't be nested, but better to be safe.
     isInContextOfEvalJs++;
     try {
         func();
         return iOSExec.nativeFetchMessages();
     } finally {
         isInContextOfEvalJs--;
     }
 };

 module.exports = iOSExec;
	/*
	*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*
	*/

	/**
	* Creates a gap bridge iframe used to notify the native code about queued
	* commands.
	*/
	var cordova = require('cordova'),
	channel = require('cordova/channel'),
	utils = require('cordova/utils'),
	base64 = require('cordova/base64'),
	// XHR mode does not work on iOS 4.2.
	// XHR mode's main advantage is working around a bug in -webkit-scroll, which
	// doesn't exist only on iOS 5.x devices.
	// IFRAME_NAV is the fastest.
	// IFRAME_HASH could be made to enable synchronous bridge calls if we wanted this feature.
	jsToNativeModes = {
	IFRAME_NAV: 0, // Default. Uses a new iframe for each poke.
	// XHR bridge appears to be flaky sometimes: CB-3900, CB-3359, CB-5457, CB-4970, CB-4998, CB-5134
	XHR_NO_PAYLOAD: 1, // About the same speed as IFRAME_NAV. Performance not about the same as IFRAME_NAV, but more variable.
	XHR_WITH_PAYLOAD: 2, // Flakey, and not as performant
	XHR_OPTIONAL_PAYLOAD: 3, // Flakey, and not as performant
	IFRAME_HASH_NO_PAYLOAD: 4, // Not fully baked. A bit faster than IFRAME_NAV, but risks jank since poke happens synchronously.
	IFRAME_HASH_WITH_PAYLOAD: 5, // Slower than no payload. Maybe since it has to be URI encoded / decoded.
	WK_WEBVIEW_BINDING: 6 // Only way that works for WKWebView :)
	},
	bridgeMode,
	execIframe,
	execHashIframe,
	hashToggle = 1,
	execXhr,
	requestCount = 0,
	vcHeaderValue = null,
	commandQueue = [], // Contains pending JS->Native messages.
	isInContextOfEvalJs = 0,
	failSafeTimerId = 0;

	function shouldBundleCommandJson() {
	if (bridgeMode === jsToNativeModes.XHR_WITH_PAYLOAD) {
	return true;
	}
	if (bridgeMode === jsToNativeModes.XHR_OPTIONAL_PAYLOAD) {
	var payloadLength = 0;
	for (var i = 0; i < commandQueue.length; ++i) {
	payloadLength += commandQueue[i].length;
	}
	// The value here was determined using the benchmark within CordovaLibApp on an iPad 3.
	return payloadLength < 4500;
	}
	return false;
	}

	function massageArgsJsToNative(args) {
	if (!args \|\| utils.typeName(args) != 'Array') {
	return args;
	}
	var ret = [];
	args.forEach(function(arg, i) {
	if (utils.typeName(arg) == 'ArrayBuffer') {
	ret.push({
	'CDVType': 'ArrayBuffer',
	'data': base64.fromArrayBuffer(arg)
	});
	} else {
	ret.push(arg);
	}
	});
	return ret;
	}

	function massageMessageNativeToJs(message) {
	if (message.CDVType == 'ArrayBuffer') {
	var stringToArrayBuffer = function(str) {
	var ret = new Uint8Array(str.length);
	for (var i = 0; i < str.length; i++) {
	ret[i] = str.charCodeAt(i);
	}
	return ret.buffer;
	};
	var base64ToArrayBuffer = function(b64) {
	return stringToArrayBuffer(atob(b64));
	};
	message = base64ToArrayBuffer(message.data);
	}
	return message;
	}

	function convertMessageToArgsNativeToJs(message) {
	var args = [];
	if (!message \|\| !message.hasOwnProperty('CDVType')) {
	args.push(message);
	} else if (message.CDVType == 'MultiPart') {
	message.messages.forEach(function(e) {
	args.push(massageMessageNativeToJs(e));
	});
	} else {
	args.push(massageMessageNativeToJs(message));
	}
	return args;
	}

	function iOSExec() {
	if (bridgeMode === undefined) {
	bridgeMode = jsToNativeModes.IFRAME_NAV;
	}

	if (window.webkit && window.webkit.messageHandlers && window.webkit.messageHandlers.cordova && window.webkit.messageHandlers.cordova.postMessage) {
	bridgeMode = jsToNativeModes.WK_WEBVIEW_BINDING;
	}

	var successCallback, failCallback, service, action, actionArgs, splitCommand;
	var callbackId = null;
	if (typeof arguments[0] !== "string") {
	// FORMAT ONE
	successCallback = arguments[0];
	failCallback = arguments[1];
	service = arguments[2];
	action = arguments[3];
	actionArgs = arguments[4];

	// Since we need to maintain backwards compatibility, we have to pass
	// an invalid callbackId even if no callback was provided since plugins
	// will be expecting it. The Cordova.exec() implementation allocates
	// an invalid callbackId and passes it even if no callbacks were given.
	callbackId = 'INVALID';
	} else {
	// FORMAT TWO, REMOVED
	try {
	splitCommand = arguments[0].split(".");
	action = splitCommand.pop();
	service = splitCommand.join(".");
	actionArgs = Array.prototype.splice.call(arguments, 1);

	console.log('The old format of this exec call has been removed (deprecated since 2.1). Change to: ' +
	"cordova.exec(null, null, \"" + service + "\", \"" + action + "\"," + JSON.stringify(actionArgs) + ");"
	);
	return;
	} catch (e) {}
	}

	// If actionArgs is not provided, default to an empty array
	actionArgs = actionArgs \|\| [];

	// Register the callbacks and add the callbackId to the positional
	// arguments if given.
	if (successCallback \|\| failCallback) {
	callbackId = service + cordova.callbackId++;
	cordova.callbacks[callbackId] =
	{success:successCallback, fail:failCallback};
	}

	actionArgs = massageArgsJsToNative(actionArgs);

	var command = [callbackId, service, action, actionArgs];

	if (bridgeMode === jsToNativeModes.WK_WEBVIEW_BINDING) {
	window.webkit.messageHandlers.cordova.postMessage(command);
	} else {
	// Stringify and queue the command. We stringify to command now to
	// effectively clone the command arguments in case they are mutated before
	// the command is executed.
	commandQueue.push(JSON.stringify(command));

	// If we're in the context of a stringByEvaluatingJavaScriptFromString call,
	// then the queue will be flushed when it returns; no need for a poke.
	// Also, if there is already a command in the queue, then we've already
	// poked the native side, so there is no reason to do so again.
	if (!isInContextOfEvalJs && commandQueue.length == 1) {
	pokeNative();
	}
	}
	}

	function pokeNative() {
	switch (bridgeMode) {
	case jsToNativeModes.XHR_NO_PAYLOAD:
	case jsToNativeModes.XHR_WITH_PAYLOAD:
	case jsToNativeModes.XHR_OPTIONAL_PAYLOAD:
	pokeNativeViaXhr();
	break;
	default: // iframe-based.
	pokeNativeViaIframe();
	}
	}

	function pokeNativeViaXhr() {
	// This prevents sending an XHR when there is already one being sent.
	// This should happen only in rare circumstances (refer to unit tests).
	if (execXhr && execXhr.readyState != 4) {
	execXhr = null;
	}
	// Re-using the XHR improves exec() performance by about 10%.
	execXhr = execXhr \|\| new XMLHttpRequest();
	// Changing this to a GET will make the XHR reach the URIProtocol on 4.2.
	// For some reason it still doesn't work though...
	// Add a timestamp to the query param to prevent caching.
	execXhr.open('HEAD', "/!gap_exec?" + (+new Date()), true);
	if (!vcHeaderValue) {
	vcHeaderValue = /.\((.)\)$/.exec(navigator.userAgent)[1];
	}
	execXhr.setRequestHeader('vc', vcHeaderValue);
	execXhr.setRequestHeader('rc', ++requestCount);
	if (shouldBundleCommandJson()) {
	execXhr.setRequestHeader('cmds', iOSExec.nativeFetchMessages());
	}
	execXhr.send(null);
	}

	function pokeNativeViaIframe() {
	// CB-5488 - Don't attempt to create iframe before document.body is available.
	if (!document.body) {
	setTimeout(pokeNativeViaIframe);
	return;
	}
	if (bridgeMode === jsToNativeModes.IFRAME_HASH_NO_PAYLOAD \|\| bridgeMode === jsToNativeModes.IFRAME_HASH_WITH_PAYLOAD) {
	// TODO: This bridge mode doesn't properly support being removed from the DOM (CB-7735)
	if (!execHashIframe) {
	execHashIframe = document.createElement('iframe');
	execHashIframe.style.display = 'none';
	document.body.appendChild(execHashIframe);
	// Hash changes don't work on about:blank, so switch it to file:///.
	execHashIframe.contentWindow.history.replaceState(null, null, 'file:///#');
	}
	// The delegate method is called only when the hash changes, so toggle it back and forth.
	hashToggle = hashToggle ^ 3;
	var hashValue = '%0' + hashToggle;
	if (bridgeMode === jsToNativeModes.IFRAME_HASH_WITH_PAYLOAD) {
	hashValue += iOSExec.nativeFetchMessages();
	}
	execHashIframe.contentWindow.location.hash = hashValue;
	} else {
	// Check if they've removed it from the DOM, and put it back if so.
	if (execIframe && execIframe.contentWindow) {
	execIframe.contentWindow.location = 'gap://ready';
	} else {
	execIframe = document.createElement('iframe');
	execIframe.style.display = 'none';
	execIframe.src = 'gap://ready';
	document.body.appendChild(execIframe);
	}
	// Use a timer to protect against iframe being unloaded during the poke (CB-7735).
	// This makes the bridge ~ 7% slower, but works around the poke getting lost
	// when the iframe is removed from the DOM.
	// An onunload listener could be used in the case where the iframe has just been
	// created, but since unload events fire only once, it doesn't work in the normal
	// case of iframe reuse (where unload will have already fired due to the attempted
	// navigation of the page).
	failSafeTimerId = setTimeout(function() {
	if (commandQueue.length) {
	pokeNative();
	}
	}, 50); // Making this > 0 improves performance (marginally) in the normal case (where it doesn't fire).
	}
	}

	iOSExec.jsToNativeModes = jsToNativeModes;

	iOSExec.setJsToNativeBridgeMode = function(mode) {
	// Remove the iFrame since it may be no longer required, and its existence
	// can trigger browser bugs.
	// https://issues.apache.org/jira/browse/CB-593
	if (execIframe) {
	if (execIframe.parentNode) {
	execIframe.parentNode.removeChild(execIframe);
	}
	execIframe = null;
	}
	bridgeMode = mode;
	};

	iOSExec.nativeFetchMessages = function() {
	// Stop listing for window detatch once native side confirms poke.
	if (failSafeTimerId) {
	clearTimeout(failSafeTimerId);
	failSafeTimerId = 0;
	}
	// Each entry in commandQueue is a JSON string already.
	if (!commandQueue.length) {
	return '';
	}
	var json = '[' + commandQueue.join(',') + ']';
	commandQueue.length = 0;
	return json;
	};

	iOSExec.nativeCallback = function(callbackId, status, message, keepCallback) {
	return iOSExec.nativeEvalAndFetch(function() {
	var success = status === 0 \|\| status === 1;
	var args = convertMessageToArgsNativeToJs(message);
	cordova.callbackFromNative(callbackId, success, status, args, keepCallback);
	});
	};

	iOSExec.nativeEvalAndFetch = function(func) {
	// This shouldn't be nested, but better to be safe.
	isInContextOfEvalJs++;
	try {
	func();
	return iOSExec.nativeFetchMessages();
	} finally {
	isInContextOfEvalJs--;
	}
	};

	module.exports = iOSExec;