CodeIgniter: PHP: AJAX File Uploader

controller.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class My_Controller extends CI_Controller {

	public function upload_files()
	{
		if ($this->input->get('qqfile'))
		{
			$file = $this->input->get('qqfile');
		}
		else if ($_FILES['qqfile'])
		{
			$file = $_FILES['qqfile']['tmp_name'];
		}

		if ($this->security->xss_clean($file))
		{
			$ext = pathinfo($file, PATHINFO_EXTENSION);
			$extensions = array('png', 'jpeg', 'jpg', 'gif', 'bmp'); // Acceptable file extensions

			if (in_array($ext, $extensions))
			{
				$directory	= './uploads/';

				if ($this->input->get('qqfile'))
				{
					$input		= fopen('php://input', 'r');
					$temp		= tmpfile();
					$realSize	= stream_copy_to_stream($input, $temp);
					fclose($input);
	
					$target = fopen($directory . $filename, 'w');
					fseek($temp, 0, SEEK_SET);
					stream_copy_to_stream($temp, $target);
					fclose($target);
				}
				else if ($_FILES['qqfile'])
				{
					move_uploaded_file($_FILES['qqfile']['tmp_name'], $directory . $filename.'.'.$ext);
				}

				$this->output->set_output(json_encode(array('success' => 'true', 'filename' => $file)));
			}
			else
			{
				$this->output->set_output(json_encode(array('error' => 'File type not supported.')));
			}
	}

?>