if getDeviceStorages() is available (FxOS >=1.1), browse all the device storages for archives, instead of the default one (given by getDeviceStorage())

Fixes #62

js/lib/archive.js

@@ -232,15 +232,46 @@ define(function(require) {
     
     /**
      * Initialize the localArchive from given directory, using DeviceStorage
-     * @param {type} storage
+     * @param {type} storages List of DeviceStorages available
      * @param {type} archiveDirectory
      */
-    LocalArchive.prototype.initializeFromDeviceStorage = function(storage, archiveDirectory) {
-        this.readTitleFilesFromStorage(storage, archiveDirectory);
-        this.readDataFilesFromStorage(storage, archiveDirectory, 0);
-        this.readMathFilesFromStorage(storage, archiveDirectory);
-        this.readMetadataFileFromStorage(storage, archiveDirectory);
-        this.readCoordinateFilesFromStorage(storage, archiveDirectory, 0);
+    LocalArchive.prototype.initializeFromDeviceStorage = function(storages, archiveDirectory) {
+        // First, we have to find which DeviceStorage has been selected by the user
+        // It is the prefix of the archive directory
+        var storageNameRegex = /^\/([^\/]+)\//;
+        var regexResults = storageNameRegex.exec(archiveDirectory);
+        var selectedStorage = null;
+        if (regexResults && regexResults.length>0) {
+            var selectedStorageName = regexResults[1];
+            for (var i=0; i<storages.length; i++) {
+                var storage = storages[i];
+                if (selectedStorageName === storage.storageName) {
+                    // We found the selected storage
+                    selectedStorage = storage;
+                }
+            }
+            if (selectedStorage === null) {
+                alert("Unable to find which device storage corresponds to directory " + archiveDirectory);
+            }
+        }
+        else {
+            // This happens with FxOS 1.0
+            // In this case, we use the first storage of the list
+            // (there should be only one)
+            if (storages.length === 1) {
+                selectedStorage = storages[0];
+            }
+            else {
+                alert("Something weird happened with the DeviceStorage API : found a directory without prefix : "
+                    + archiveDirectory + ", but there were " + storages.length
+                    + " storages found with getDeviceStorages instead of 1");
+            }
+        }
+        this.readTitleFilesFromStorage(selectedStorage, archiveDirectory);
+        this.readDataFilesFromStorage(selectedStorage, archiveDirectory, 0);
+        this.readMathFilesFromStorage(selectedStorage, archiveDirectory);
+        this.readMetadataFileFromStorage(selectedStorage, archiveDirectory);
+        this.readCoordinateFilesFromStorage(selectedStorage, archiveDirectory, 0);
     };
 
     /**
@@ -684,12 +715,12 @@ define(function(require) {
     /**
      *  Scans the DeviceStorage for archives
      * 
-     * @param storage DeviceStorage instance
+     * @param storages List of DeviceStorage instances
      * @param callbackFunction Function to call with the list of directories where archives are found
      */
-    LocalArchive.scanForArchives = function(storage, callbackFunction) {
+    LocalArchive.scanForArchives = function(storages, callbackFunction) {
         var directories = [];
-        var cursor = storage.enumerate();
+        var cursor = util.enumerateAll(storages);
         cursor.onerror = function() {
             alert("Error scanning your SD card : " + cursor.error
                     +". If you're using the Firefox OS Simulator, please put the archives in a 'fake-sdcard' directory inside your Firefox profile (ex : ~/.mozilla/firefox/xxxx.default/extensions/r2d2b2g@mozilla.org/profile/fake-sdcard/wikipedia_small_2010-08-14)");

js/lib/util.js

@@ -95,7 +95,72 @@ define(function(require) {
 
         return (r > 0 ? enc.slice(0, r - 3) : enc) + '==='.slice(r || 3);
     }
+    
+    
+    /**
+     * This function emulates a "composite" storage enumeration
+     * (i.e. returns files from all the storage areas)
+     * This is needed since the removal of composite storage :
+     * see https://bugzilla.mozilla.org/show_bug.cgi?id=885753
+     * 
+     * This code was copied (with only slight modifications) from Gaia source code :
+     * https://bug893282.bugzilla.mozilla.org/attachment.cgi?id=785076
+     * 
+     * @param {type} storages List of DeviceStorage instances
+     * @returns {_L22.enumerateAll.cursor} Cursor of files found in device storages
+     */
+    function enumerateAll(storages) {
+        var storageIndex = 0;
+        var ds_cursor = null;
 
+        var cursor = {
+            continue: function cursor_continue() {
+                ds_cursor.continue();
+            }
+        };
+
+        function enumerateNextStorage() {
+            ds_cursor = storages[storageIndex].enumerate();
+            ds_cursor.onsuccess = onsuccess;
+            ds_cursor.onerror = onerror;
+        };
+
+        function onsuccess(e) {
+            cursor.result = e.target.result;
+            if (!cursor.result) {
+                storageIndex++;
+                if (storageIndex < storages.length) {
+                    enumerateNextStorage();
+                    return;
+                }
+                // If we've run out of storages, then we fall through and call
+                // onsuccess with the null result.
+            }
+            if (cursor.onsuccess) {
+                try {
+                    cursor.onsuccess(e);
+                } catch (err) {
+                    console.warn('enumerateAll onsuccess threw', err);
+                }
+            }
+        };
+
+        function onerror(e) {
+            cursor.error = e.target.error;
+            if (cursor.onerror) {
+                try {
+                    cursor.onerror(e);
+                } catch (err) {
+                    console.warn('enumerateAll onerror threw', err);
+                }
+            }
+        };
+
+        enumerateNextStorage();
+        return cursor;
+    }
+    
+    
     
     /**
      * Functions and classes exposed by this module
@@ -105,6 +170,7 @@ define(function(require) {
         readIntegerFrom4Bytes: readIntegerFrom4Bytes,
         readIntegerFrom2Bytes : readIntegerFrom2Bytes,
         uint8ArrayToHex : uint8ArrayToHex,
-        uint8ArrayToBase64 : uint8ArrayToBase64
+        uint8ArrayToBase64 : uint8ArrayToBase64,
+        enumerateAll : enumerateAll
     };
 });