Added FilesystemException to handle errors on local filesystem.

src/Composer/Downloader/FilesystemException.php

@@ -0,0 +1,26 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Downloader;
+
+/**
+ * Exception thrown when issues exist on local filesystem
+ * 
+ * @author Javier Spagnoletti <jspagnoletti@javierspagnoletti.com.ar>
+ */
+class FilesystemException extends \Exception
+{
+    public function __construct($message = null, $code = null, \Exception $previous = null)
+    {
+        parent::__construct("Filesystem exception: \n".$message, $code, $previous);
+    }
+}