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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 var GetAvailability = requireNative('v8_context').GetAvailability;
      6 var GetGlobal = requireNative('sendRequest').GetGlobal;
      7 
      8 // Utility for setting chrome.*.lastError.
      9 //
     10 // A utility here is useful for two reasons:
     11 //  1. For backwards compatibility we need to set chrome.extension.lastError,
     12 //     but not all contexts actually have access to the extension namespace.
     13 //  2. When calling across contexts, the global object that gets lastError set
     14 //     needs to be that of the caller. We force callers to explicitly specify
     15 //     the chrome object to try to prevent bugs here.
     16 
     17 /**
     18  * Sets the last error for |name| on |targetChrome| to |message| with an
     19  * optional |stack|.
     20  */
     21 function set(name, message, stack, targetChrome) {
     22   var errorMessage = name + ': ' + message;
     23   if (stack != null && stack != '')
     24     errorMessage += '\n' + stack;
     25 
     26   if (!targetChrome)
     27     throw new Error('No chrome object to set error: ' + errorMessage);
     28   clear(targetChrome);  // in case somebody has set a sneaky getter/setter
     29 
     30   var errorObject = { message: message };
     31   if (GetAvailability('extension.lastError').is_available)
     32     targetChrome.extension.lastError = errorObject;
     33 
     34   assertRuntimeIsAvailable();
     35   targetChrome.runtime.lastError = errorObject;
     36 };
     37 
     38 /**
     39  * Clears the last error on |targetChrome|.
     40  */
     41 function clear(targetChrome) {
     42   if (!targetChrome)
     43     throw new Error('No target chrome to clear error');
     44 
     45   if (GetAvailability('extension.lastError').is_available)
     46     delete targetChrome.extension.lastError;
     47 
     48   assertRuntimeIsAvailable();
     49   delete targetChrome.runtime.lastError;
     50 };
     51 
     52 function assertRuntimeIsAvailable() {
     53   // chrome.runtime should always be available, but maybe it's disappeared for
     54   // some reason? Add debugging for http://crbug.com/258526.
     55   var runtimeAvailability = GetAvailability('runtime.lastError');
     56   if (!runtimeAvailability.is_available) {
     57     throw new Error('runtime.lastError is not available: ' +
     58                     runtimeAvailability.message);
     59   }
     60   if (!chrome.runtime)
     61     throw new Error('runtime namespace is null or undefined');
     62 }
     63 
     64 /**
     65  * Runs |callback(args)| with last error args as in set().
     66  *
     67  * The target chrome object is the global object's of the callback, so this
     68  * method won't work if the real callback has been wrapped (etc).
     69  */
     70 function run(name, message, stack, callback, args) {
     71   var targetChrome = GetGlobal(callback).chrome;
     72   set(name, message, stack, targetChrome);
     73   try {
     74     $Function.apply(callback, undefined, args);
     75   } finally {
     76     clear(targetChrome);
     77   }
     78 }
     79 
     80 exports.clear = clear;
     81 exports.set = set;
     82 exports.run = run;
     83