Implement File API

lib/io.js

 //
 // No direct file system access, using FileSystem API
 //
 
 var IO = exports.IO =
 {
-  _getFileEntry: function(file, create, successCallback, errorCallback)
-  {
-    if (file instanceof FakeFile)
-      file = file.path;
-    else if ("spec" in file)
-      file = file.spec;
-
-    // Remove directory path - we operate on a single directory in Chrome
-    file = file.replace(/^.*[\/\\]/, "");
-
-    // We request a gigabyte of space, just in case
-    (window.requestFileSystem || window.webkitRequestFileSystem)(window.PERSISTENT, 1024*1024*1024, function(fs)
-    {
-      fs.root.getFile(file, {create: create}, function(fileEntry)
-      {
-        successCallback(fs, fileEntry);
-      }, errorCallback);
-    }, errorCallback);
-  },
-
   lineBreak: "\n",
 
   resolveFilePath: function(path)
   {
     return new FakeFile(path);
   },
 
   readFromFile: function(file, decode, listener, callback, timeLineID)
   {
     if ("spec" in file && /^defaults\b/.test(file.spec))
     {
       // Code attempts to read the default patterns.ini, we don't have that.
       // Make sure to execute first-run actions instead.
       callback(null);
       if (localStorage.currentVersion)
         seenDataCorruption = true;
       delete localStorage.currentVersion;
       return;
     }
 
-    this._getFileEntry(file, false, function(fs, fileEntry)
+    _fileSystem.read(file, function(result)
     {
-      fileEntry.file(function(file)
+      if (result.error)
+        callback(result.error);
+      else
       {
-        var reader = new FileReader();
-        reader.onloadend = function()
-        {
-          if (reader.error)
-            callback(reader.error);
-          else
-          {
-            var lines = reader.result.split(/[\r\n]+/);
-            for (var i = 0; i < lines.length; i++)
-              listener.process(lines[i]);
-            listener.process(null);
-            callback(null);
-          }
-        };
-        reader.readAsText(file);
-      }, callback);
-    }, callback);
+        var lines = result.data.split(/[\r\n]+/);
+        for (var i = 0; i < lines.length; i++)
+          listener.process(lines[i]);
+        listener.process(null);
+        callback(null);
+      }
+    });
   },
 
   writeToFile: function(file, encode, data, callback, timeLineID)
   {
-    this._getFileEntry(file, true, function(fs, fileEntry)
-    {
-      fileEntry.createWriter(function(writer)
-      {
-        var executeWriteOperation = function(op, nextOperation)
-        {
-          writer.onwriteend = function()
-          {
-            if (writer.error)
-              callback(writer.error);
-            else
-              nextOperation();
-          }.bind(this);
-
-          op();
-        }.bind(this);
-
-        executeWriteOperation(writer.truncate.bind(writer, 0), function()
-        {
-          var blob;
-          try
-          {
-            blob = new Blob([data.join(this.lineBreak) + this.lineBreak], {type: "text/plain"});
-          }
-          catch (e)
-          {
-            if (!(e instanceof TypeError))
-              throw e;
-
-            // Blob wasn't a constructor before Chrome 20
-            var builder = new (window.BlobBuilder || window.WebKitBlobBuilder);
-            builder.append(data.join(this.lineBreak) + this.lineBreak);
-            blob = builder.getBlob("text/plain");
-          }
-          executeWriteOperation(writer.write.bind(writer, blob), callback.bind(null, null));
-        }.bind(this));
-      }.bind(this), callback);
-    }.bind(this), callback);
+    var content = data.join(this.lineBreak) + this.lineBreak;
+    _fileSystem.write(file, content, callback);
   },
 
   copyFile: function(fromFile, toFile, callback)
   {
     // Simply combine read and write operations
     var data = [];
     this.readFromFile(fromFile, false, {
       process: function(line)
       {
         if (line !== null)
           data.push(line);
       }
     }, function(e)
     {
       if (e)
         callback(e);
       else
         this.writeToFile(toFile, false, data, callback);
     }.bind(this));
   },
 
   renameFile: function(fromFile, newName, callback)
   {
-    this._getFileEntry(fromFile, false, function(fs, fileEntry)
-    {
-      fileEntry.moveTo(fs.root, newName, function()
-      {
-        callback(null);
-      }, callback);
-    }, callback);
+    _fileSystem.move(fromFile, newName, callback);
   },
 
   removeFile: function(file, callback)
   {
-    this._getFileEntry(file, false, function(fs, fileEntry)
-    {
-      fileEntry.remove(function()
-      {
-        callback(null);
-      }, callback);
-    }, callback);
+    _fileSystem.remove(file, callback);
   },
 
   statFile: function(file, callback)
   {
-    this._getFileEntry(file, false, function(fs, fileEntry)
-    {
-      fileEntry.getMetadata(function(metadata)
-      {
-        callback(null, {
-          exists: true,
-          isDirectory: fileEntry.isDirectory,
-          isFile: fileEntry.isFile,
-          lastModified: metadata.modificationTime.getTime()
-        });
-      }, callback);
-    }, callback);
+    _fileSystem.stat(file, callback);
   }
 };