ci-bonfire / Sprint

system/libraries/Upload.php

<?php

For compatibility and reusability of your code, PSR1 recommends that a file should introduce either new symbols (like classes, functions, etc.) or have side-effects (like outputting something, or including other files), but not both at the same time. The first symbol is defined on line 49 and the first side effect is on line 38.

/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2015, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
 * @copyright	Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	http://codeigniter.com
 * @since	Version 1.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * File Uploading Class
 *
 * @package		CodeIgniter
 * @subpackage	Libraries
 * @category	Uploads
 * @author		EllisLab Dev Team
 * @link		http://codeigniter.com/user_guide/libraries/file_uploading.html
 */
class CI_Upload {

	/**
	 * Maximum file size
	 *
	 * @var	int
	 */
	public $max_size = 0;

	/**
	 * Maximum image width
	 *
	 * @var	int
	 */
	public $max_width = 0;

	/**
	 * Maximum image height
	 *
	 * @var	int
	 */
	public $max_height = 0;

	/**
	 * Minimum image width
	 *
	 * @var	int
	 */
	public $min_width = 0;

	/**
	 * Minimum image height
	 *
	 * @var	int
	 */
	public $min_height = 0;

	/**
	 * Maximum filename length
	 *
	 * @var	int
	 */
	public $max_filename = 0;

	/**
	 * Maximum duplicate filename increment ID
	 *
	 * @var	int
	 */
	public $max_filename_increment = 100;

	/**
	 * Allowed file types
	 *
	 * @var	string
	 */
	public $allowed_types = '';

	/**
	 * Temporary filename
	 *
	 * @var	string
	 */
	public $file_temp = '';

	/**
	 * Filename
	 *
	 * @var	string
	 */
	public $file_name = '';

	/**
	 * Original filename
	 *
	 * @var	string
	 */
	public $orig_name = '';

	/**
	 * File type
	 *
	 * @var	string
	 */
	public $file_type = '';

	/**
	 * File size
	 *
	 * @var	int
	 */
	public $file_size = NULL;

	/**
	 * Filename extension
	 *
	 * @var	string
	 */
	public $file_ext = '';

	/**
	 * Force filename extension to lowercase
	 *
	 * @var	string
	 */
	public $file_ext_tolower = FALSE;

	/**
	 * Upload path
	 *
	 * @var	string
	 */
	public $upload_path = '';

	/**
	 * Overwrite flag
	 *
	 * @var	bool
	 */
	public $overwrite = FALSE;

	/**
	 * Obfuscate filename flag
	 *
	 * @var	bool
	 */
	public $encrypt_name = FALSE;

	/**
	 * Is image flag
	 *
	 * @var	bool
	 */
	public $is_image = FALSE;

	/**
	 * Image width
	 *
	 * @var	int
	 */
	public $image_width = NULL;

	/**
	 * Image height
	 *
	 * @var	int
	 */
	public $image_height = NULL;

	/**
	 * Image type
	 *
	 * @var	string
	 */
	public $image_type = '';

	/**
	 * Image size string
	 *
	 * @var	string
	 */
	public $image_size_str = '';

	/**
	 * Error messages list
	 *
	 * @var	array
	 */
	public $error_msg = array();

	/**
	 * Remove spaces flag
	 *
	 * @var	bool
	 */
	public $remove_spaces = TRUE;

	/**
	 * MIME detection flag
	 *
	 * @var	bool
	 */
	public $detect_mime = TRUE;

	/**
	 * XSS filter flag
	 *
	 * @var	bool
	 */
	public $xss_clean = FALSE;

	/**
	 * Apache mod_mime fix flag
	 *
	 * @var	bool
	 */
	public $mod_mime_fix = TRUE;

	/**
	 * Temporary filename prefix
	 *
	 * @var	string
	 */
	public $temp_prefix = 'temp_file_';

	/**
	 * Filename sent by the client
	 *
	 * @var	bool
	 */
	public $client_name = '';

	// --------------------------------------------------------------------

	/**
	 * Filename override
	 *
	 * @var	string
	 */
	protected $_file_name_override = '';

	/**
	 * MIME types list
	 *
	 * @var	array
	 */
	protected $_mimes = array();

	/**
	 * CI Singleton
	 *
	 * @var	object
	 */
	protected $_CI;

	// --------------------------------------------------------------------

	/**
	 * Constructor
	 *
	 * @param	array	$props
	 * @return	void
	 */
	public function __construct($config = array())
	{
		empty($config) OR $this->initialize($config, FALSE);

		$this->_mimes =& get_mimes();
		$this->_CI =& get_instance();

		log_message('info', 'Upload Class Initialized');
	}

	// --------------------------------------------------------------------

	/**
	 * Initialize preferences
	 *
	 * @param	array	$config
	 * @param	bool	$reset
	 * @return	CI_Upload
	 */
	public function initialize(array $config = array(), $reset = TRUE)
	{
		$reflection = new ReflectionClass($this);

		if ($reset === TRUE)
		{
			$defaults = $reflection->getDefaultProperties();
			foreach (array_keys($defaults) as $key)
			{
				if ($key[0] === '_')
				{
					continue;
				}

				if (isset($config[$key]))
				{
					if ($reflection->hasMethod('set_'.$key))
					{
						$this->{'set_'.$key}($config[$key]);
					}
					else
					{
						$this->$key = $config[$key];
					}
				}
				else
				{
					$this->$key = $defaults[$key];
				}
			}
		}
		else
		{
			foreach ($config as $key => &$value)
			{
				if ($key[0] !== '_' && $reflection->hasProperty($key))
				{
					if ($reflection->hasMethod('set_'.$key))
					{
						$this->{'set_'.$key}($value);
					}
					else
					{
						$this->$key = $value;
					}
				}
			}
		}

		// if a file_name was provided in the config, use it instead of the user input
		// supplied file name for all uploads until initialized again
		$this->_file_name_override = $this->file_name;
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Perform the file upload
	 *
	 * @param	string	$field
	 * @return	bool
	 */
	public function do_upload($field = 'userfile')
	{
		// Is $_FILES[$field] set? If not, no reason to continue.
		if (isset($_FILES[$field]))
		{
			$_file = $_FILES[$field];
		}
		// Does the field name contain array notation?
		elseif (($c = preg_match_all('/(?:^[^\[]+)|\[[^]]*\]/', $field, $matches)) > 1)
		{
			$_file = $_FILES;
			for ($i = 0; $i < $c; $i++)
			{
				// We can't track numeric iterations, only full field names are accepted
				if (($field = trim($matches[0][$i], '[]')) === '' OR ! isset($_file[$field]))
				{
					$_file = NULL;
					break;
				}

				$_file = $_file[$field];
			}
		}

		if ( ! isset($_file))
		{
			$this->set_error('upload_no_file_selected', 'debug');
			return FALSE;
		}

		// Is the upload path valid?
		if ( ! $this->validate_upload_path())
		{
			// errors will already be set by validate_upload_path() so just return FALSE
			return FALSE;
		}

		// Was the file able to be uploaded? If not, determine the reason why.
		if ( ! is_uploaded_file($_file['tmp_name']))
		{
			$error = isset($_file['error']) ? $_file['error'] : 4;

			switch ($error)
			{
				case UPLOAD_ERR_INI_SIZE:
					$this->set_error('upload_file_exceeds_limit', 'info');
					break;
				case UPLOAD_ERR_FORM_SIZE:
					$this->set_error('upload_file_exceeds_form_limit', 'info');
					break;
				case UPLOAD_ERR_PARTIAL:
					$this->set_error('upload_file_partial', 'debug');
					break;
				case UPLOAD_ERR_NO_FILE:
					$this->set_error('upload_no_file_selected', 'debug');
					break;
				case UPLOAD_ERR_NO_TMP_DIR:
					$this->set_error('upload_no_temp_directory', 'error');
					break;
				case UPLOAD_ERR_CANT_WRITE:
					$this->set_error('upload_unable_to_write_file', 'error');
					break;
				case UPLOAD_ERR_EXTENSION:
					$this->set_error('upload_stopped_by_extension', 'debug');
					break;
				default:
					$this->set_error('upload_no_file_selected', 'debug');
					break;
			}

			return FALSE;
		}

		// Set the uploaded data as class variables
		$this->file_temp = $_file['tmp_name'];
		$this->file_size = $_file['size'];

		// Skip MIME type detection?
		if ($this->detect_mime !== FALSE)
		{
			$this->_file_mime_type($_file);
		}

		$this->file_type = preg_replace('/^(.+?);.*$/', '\\1', $this->file_type);
		$this->file_type = strtolower(trim(stripslashes($this->file_type), '"'));
		$this->file_name = $this->_prep_filename($_file['name']);
		$this->file_ext	 = $this->get_extension($this->file_name);
		$this->client_name = $this->file_name;

		// Is the file type allowed to be uploaded?
		if ( ! $this->is_allowed_filetype())
		{
			$this->set_error('upload_invalid_filetype', 'debug');
			return FALSE;
		}

		// if we're overriding, let's now make sure the new name and type is allowed
		if ($this->_file_name_override !== '')
		{
			$this->file_name = $this->_prep_filename($this->_file_name_override);

			// If no extension was provided in the file_name config item, use the uploaded one
			if (strpos($this->_file_name_override, '.') === FALSE)
			{
				$this->file_name .= $this->file_ext;
			}
			else
			{
				// An extension was provided, let's have it!
				$this->file_ext	= $this->get_extension($this->_file_name_override);
			}

			if ( ! $this->is_allowed_filetype(TRUE))
			{
				$this->set_error('upload_invalid_filetype', 'debug');
				return FALSE;
			}
		}

		// Convert the file size to kilobytes
		if ($this->file_size > 0)
		{
			$this->file_size = round($this->file_size/1024, 2);
		}

		// Is the file size within the allowed maximum?
		if ( ! $this->is_allowed_filesize())
		{
			$this->set_error('upload_invalid_filesize', 'info');
			return FALSE;
		}

		// Are the image dimensions within the allowed size?
		// Note: This can fail if the server has an open_basedir restriction.
		if ( ! $this->is_allowed_dimensions())
		{
			$this->set_error('upload_invalid_dimensions', 'info');
			return FALSE;
		}

		// Sanitize the file name for security
		$this->file_name = $this->_CI->security->sanitize_filename($this->file_name);

		// Truncate the file name if it's too long
		if ($this->max_filename > 0)
		{
			$this->file_name = $this->limit_filename_length($this->file_name, $this->max_filename);
		}

		// Remove white spaces in the name
		if ($this->remove_spaces === TRUE)
		{
			$this->file_name = preg_replace('/\s+/', '_', $this->file_name);
		}

		/*
		 * Validate the file name
		 * This function appends an number onto the end of
		 * the file if one with the same name already exists.
		 * If it returns false there was a problem.
		 */
		$this->orig_name = $this->file_name;
		if (FALSE === ($this->file_name = $this->set_filename($this->upload_path, $this->file_name)))
		{
			return FALSE;
		}

		/*
		 * Run the file through the XSS hacking filter
		 * This helps prevent malicious code from being
		 * embedded within a file. Scripts can easily
		 * be disguised as images or other file types.
		 */
		if ($this->xss_clean && $this->do_xss_clean() === FALSE)
		{
			$this->set_error('upload_unable_to_write_file', 'error');
			return FALSE;
		}

		/*
		 * Move the file to the final destination
		 * To deal with different server configurations
		 * we'll attempt to use copy() first. If that fails
		 * we'll use move_uploaded_file(). One of the two should
		 * reliably work in most environments
		 */
		if ( ! @copy($this->file_temp, $this->upload_path.$this->file_name))
		{
			if ( ! @move_uploaded_file($this->file_temp, $this->upload_path.$this->file_name))
			{
				$this->set_error('upload_destination_error', 'error');
				return FALSE;
			}
		}

		/*
		 * Set the finalized image dimensions
		 * This sets the image width/height (assuming the
		 * file was an image). We use this information
		 * in the "data" function.
		 */
		$this->set_image_properties($this->upload_path.$this->file_name);

		return TRUE;
	}

	// --------------------------------------------------------------------

	/**
	 * Finalized Data Array
	 *
	 * Returns an associative array containing all of the information
	 * related to the upload, allowing the developer easy access in one array.
	 *
	 * @param	string	$index
	 * @return	mixed
	 */
	public function data($index = NULL)
	{
		$data = array(
				'file_name'		=> $this->file_name,
				'file_type'		=> $this->file_type,
				'file_path'		=> $this->upload_path,
				'full_path'		=> $this->upload_path.$this->file_name,
				'raw_name'		=> str_replace($this->file_ext, '', $this->file_name),
				'orig_name'		=> $this->orig_name,
				'client_name'		=> $this->client_name,
				'file_ext'		=> $this->file_ext,
				'file_size'		=> $this->file_size,
				'is_image'		=> $this->is_image(),
				'image_width'		=> $this->image_width,
				'image_height'		=> $this->image_height,
				'image_type'		=> $this->image_type,
				'image_size_str'	=> $this->image_size_str,
			);

		if ( ! empty($index))
		{
			return isset($data[$index]) ? $data[$index] : NULL;
		}

		return $data;
	}

	// --------------------------------------------------------------------

	/**
	 * Set Upload Path
	 *
	 * @param	string	$path
	 * @return	CI_Upload
	 */
	public function set_upload_path($path)
	{
		// Make sure it has a trailing slash
		$this->upload_path = rtrim($path, '/').'/';
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Set the file name
	 *
	 * This function takes a filename/path as input and looks for the
	 * existence of a file with the same name. If found, it will append a
	 * number to the end of the filename to avoid overwriting a pre-existing file.
	 *
	 * @param	string	$path
	 * @param	string	$filename
	 * @return	string
	 */
	public function set_filename($path, $filename)
	{
		if ($this->encrypt_name === TRUE)
		{
			$filename = md5(uniqid(mt_rand())).$this->file_ext;
		}

		if ($this->overwrite === TRUE OR ! file_exists($path.$filename))
		{
			return $filename;
		}

		$filename = str_replace($this->file_ext, '', $filename);

		$new_filename = '';
		for ($i = 1; $i < $this->max_filename_increment; $i++)
		{
			if ( ! file_exists($path.$filename.$i.$this->file_ext))
			{
				$new_filename = $filename.$i.$this->file_ext;
				break;
			}
		}

		if ($new_filename === '')
		{
			$this->set_error('upload_bad_filename', 'debug');
			return FALSE;
		}
		else
		{
			return $new_filename;
		}
	}

	// --------------------------------------------------------------------

	/**
	 * Set Maximum File Size
	 *
	 * @param	int	$n
	 * @return	CI_Upload
	 */
	public function set_max_filesize($n)
	{
		$this->max_size = ($n < 0) ? 0 : (int) $n;
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Set Maximum File Size
	 *
	 * An internal alias to set_max_filesize() to help with configuration
	 * as initialize() will look for a set_<property_name>() method ...
	 *
	 * @param	int	$n
	 * @return	CI_Upload
	 */
	protected function set_max_size($n)
	{
		return $this->set_max_filesize($n);
	}

	// --------------------------------------------------------------------

	/**
	 * Set Maximum File Name Length
	 *
	 * @param	int	$n
	 * @return	CI_Upload
	 */
	public function set_max_filename($n)
	{
		$this->max_filename = ($n < 0) ? 0 : (int) $n;
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Set Maximum Image Width
	 *
	 * @param	int	$n
	 * @return	CI_Upload
	 */
	public function set_max_width($n)
	{
		$this->max_width = ($n < 0) ? 0 : (int) $n;
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Set Maximum Image Height
	 *
	 * @param	int	$n
	 * @return	CI_Upload
	 */
	public function set_max_height($n)
	{
		$this->max_height = ($n < 0) ? 0 : (int) $n;
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Set minimum image width
	 *
	 * @param	int	$n
	 * @return	CI_Upload
	 */
	public function set_min_width($n)
	{
		$this->min_width = ($n < 0) ? 0 : (int) $n;
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Set minimum image height
	 *
	 * @param	int	$n
	 * @return	CI_Upload
	 */
	public function set_min_height($n)
	{
		$this->min_height = ($n < 0) ? 0 : (int) $n;
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Set Allowed File Types
	 *
	 * @param	mixed	$types
	 * @return	CI_Upload
	 */
	public function set_allowed_types($types)
	{
		$this->allowed_types = (is_array($types) OR $types === '*')
			? $types
			: explode('|', $types);
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Set Image Properties
	 *
	 * Uses GD to determine the width/height/type of image
	 *
	 * @param	string	$path
	 * @return	CI_Upload
	 */
	public function set_image_properties($path = '')
	{
		if ($this->is_image() && function_exists('getimagesize'))
		{
			if (FALSE !== ($D = @getimagesize($path)))
			{
				$types = array(1 => 'gif', 2 => 'jpeg', 3 => 'png');

				$this->image_width	= $D[0];
				$this->image_height	= $D[1];
				$this->image_type	= isset($types[$D[2]]) ? $types[$D[2]] : 'unknown';
				$this->image_size_str	= $D[3]; // string containing height and width
			}
		}

		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Set XSS Clean
	 *
	 * Enables the XSS flag so that the file that was uploaded
	 * will be run through the XSS filter.
	 *
	 * @param	bool	$flag
	 * @return	CI_Upload
	 */
	public function set_xss_clean($flag = FALSE)
	{
		$this->xss_clean = ($flag === TRUE);
		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Validate the image
	 *
	 * @return	bool
	 */
	public function is_image()
	{
		// IE will sometimes return odd mime-types during upload, so here we just standardize all
		// jpegs or pngs to the same file type.

		$png_mimes  = array('image/x-png');
		$jpeg_mimes = array('image/jpg', 'image/jpe', 'image/jpeg', 'image/pjpeg');

		if (in_array($this->file_type, $png_mimes))
		{
			$this->file_type = 'image/png';
		}
		elseif (in_array($this->file_type, $jpeg_mimes))
		{
			$this->file_type = 'image/jpeg';
		}

		$img_mimes = array('image/gif',	'image/jpeg', 'image/png');

		return in_array($this->file_type, $img_mimes, TRUE);
	}

	// --------------------------------------------------------------------

	/**
	 * Verify that the filetype is allowed
	 *
	 * @param	bool	$ignore_mime
	 * @return	bool
	 */
	public function is_allowed_filetype($ignore_mime = FALSE)
	{
		if ($this->allowed_types === '*')
		{
			return TRUE;
		}

		if (empty($this->allowed_types) OR ! is_array($this->allowed_types))
		{
			$this->set_error('upload_no_file_types', 'debug');
			return FALSE;
		}

		$ext = strtolower(ltrim($this->file_ext, '.'));

		if ( ! in_array($ext, $this->allowed_types, TRUE))
		{
			return FALSE;
		}

		// Images get some additional checks
		if (in_array($ext, array('gif', 'jpg', 'jpeg', 'jpe', 'png'), TRUE) && @getimagesize($this->file_temp) === FALSE)
		{
			return FALSE;
		}

		if ($ignore_mime === TRUE)
		{
			return TRUE;
		}

		if (isset($this->_mimes[$ext]))
		{
			return is_array($this->_mimes[$ext])
				? in_array($this->file_type, $this->_mimes[$ext], TRUE)
				: ($this->_mimes[$ext] === $this->file_type);
		}

		return FALSE;
	}

	// --------------------------------------------------------------------

	/**
	 * Verify that the file is within the allowed size
	 *
	 * @return	bool
	 */
	public function is_allowed_filesize()
	{
		return ($this->max_size === 0 OR $this->max_size > $this->file_size);
	}

	// --------------------------------------------------------------------

	/**
	 * Verify that the image is within the allowed width/height
	 *
	 * @return	bool
	 */
	public function is_allowed_dimensions()
	{
		if ( ! $this->is_image())
		{
			return TRUE;
		}

		if (function_exists('getimagesize'))
		{
			$D = @getimagesize($this->file_temp);

			if ($this->max_width > 0 && $D[0] > $this->max_width)
			{
				return FALSE;
			}

			if ($this->max_height > 0 && $D[1] > $this->max_height)
			{
				return FALSE;
			}

			if ($this->min_width > 0 && $D[0] < $this->min_width)
			{
				return FALSE;
			}

			if ($this->min_height > 0 && $D[1] < $this->min_height)
			{
				return FALSE;
			}
		}

		return TRUE;
	}

	// --------------------------------------------------------------------

	/**
	 * Validate Upload Path
	 *
	 * Verifies that it is a valid upload path with proper permissions.
	 *
	 * @return	bool
	 */
	public function validate_upload_path()
	{
		if ($this->upload_path === '')
		{
			$this->set_error('upload_no_filepath', 'error');
			return FALSE;
		}

		if (realpath($this->upload_path) !== FALSE)
		{
			$this->upload_path = str_replace('\\', '/', realpath($this->upload_path));
		}

		if ( ! is_dir($this->upload_path))
		{
			$this->set_error('upload_no_filepath', 'error');
			return FALSE;
		}

		if ( ! is_really_writable($this->upload_path))
		{
			$this->set_error('upload_not_writable', 'error');
			return FALSE;
		}

		$this->upload_path = preg_replace('/(.+?)\/*$/', '\\1/',  $this->upload_path);
		return TRUE;
	}

	// --------------------------------------------------------------------

	/**
	 * Extract the file extension
	 *
	 * @param	string	$filename
	 * @return	string
	 */
	public function get_extension($filename)
	{
		$x = explode('.', $filename);

		if (count($x) === 1)
		{
			return '';
		}

		$ext = ($this->file_ext_tolower) ? strtolower(end($x)) : end($x);
		return '.'.$ext;
	}

	// --------------------------------------------------------------------

	/**
	 * Limit the File Name Length
	 *
	 * @param	string	$filename
	 * @param	int	$length
	 * @return	string
	 */
	public function limit_filename_length($filename, $length)
	{
		if (strlen($filename) < $length)
		{
			return $filename;
		}

		$ext = '';
		if (strpos($filename, '.') !== FALSE)
		{
			$parts		= explode('.', $filename);
			$ext		= '.'.array_pop($parts);
			$filename	= implode('.', $parts);
		}

		return substr($filename, 0, ($length - strlen($ext))).$ext;
	}

	// --------------------------------------------------------------------

	/**
	 * Runs the file through the XSS clean function
	 *
	 * This prevents people from embedding malicious code in their files.
	 * I'm not sure that it won't negatively affect certain files in unexpected ways,
	 * but so far I haven't found that it causes trouble.
	 *
	 * @return	string
	 */
	public function do_xss_clean()
	{
		$file = $this->file_temp;

		if (filesize($file) == 0)
		{
			return FALSE;
		}

		if (memory_get_usage() && ($memory_limit = ini_get('memory_limit')))
		{
			$memory_limit *= 1024 * 1024;

			// There was a bug/behavioural change in PHP 5.2, where numbers over one million get output
			// into scientific notation. number_format() ensures this number is an integer
			// http://bugs.php.net/bug.php?id=43053

			$memory_limit = number_format(ceil(filesize($file) + $memory_limit), 0, '.', '');

			ini_set('memory_limit', $memory_limit); // When an integer is used, the value is measured in bytes. - PHP.net
		}

		// If the file being uploaded is an image, then we should have no problem with XSS attacks (in theory), but
		// IE can be fooled into mime-type detecting a malformed image as an html file, thus executing an XSS attack on anyone
		// using IE who looks at the image. It does this by inspecting the first 255 bytes of an image. To get around this
		// CI will itself look at the first 255 bytes of an image to determine its relative safety. This can save a lot of
		// processor power and time if it is actually a clean image, as it will be in nearly all instances _except_ an
		// attempted XSS attack.

		if (function_exists('getimagesize') && @getimagesize($file) !== FALSE)
		{
			if (($file = @fopen($file, 'rb')) === FALSE) // "b" to force binary
			{
				return FALSE; // Couldn't open the file, return FALSE
			}

			$opening_bytes = fread($file, 256);
			fclose($file);

			// These are known to throw IE into mime-type detection chaos
			// <a, <body, <head, <html, <img, <plaintext, <pre, <script, <table, <title
			// title is basically just in SVG, but we filter it anyhow

			// if it's an image or no "triggers" detected in the first 256 bytes - we're good
			return ! preg_match('/<(a|body|head|html|img|plaintext|pre|script|table|title)[\s>]/i', $opening_bytes);
		}

		if (($data = @file_get_contents($file)) === FALSE)
		{
			return FALSE;
		}

		return $this->_CI->security->xss_clean($data, TRUE);
	}

	// --------------------------------------------------------------------

	/**
	 * Set an error message
	 *
	 * @param	string	$msg
	 * @return	CI_Upload
	 */
	public function set_error($msg, $log_level = 'error')
	{
		$this->_CI->lang->load('upload');

		is_array($msg) OR $msg = array($msg);
		foreach ($msg as $val)
		{
			$msg = ($this->_CI->lang->line($val) === FALSE) ? $val : $this->_CI->lang->line($val);
			$this->error_msg[] = $msg;
			log_message($log_level, $msg);
		}

		return $this;
	}

	// --------------------------------------------------------------------

	/**
	 * Display the error message
	 *
	 * @param	string	$open
	 * @param	string	$close
	 * @return	string
	 */
	public function display_errors($open = '<p>', $close = '</p>')
	{
		return (count($this->error_msg) > 0) ? $open.implode($close.$open, $this->error_msg).$close : '';
	}

	// --------------------------------------------------------------------

	/**
	 * Prep Filename
	 *
	 * Prevents possible script execution from Apache's handling
	 * of files' multiple extensions.
	 *
	 * @link	http://httpd.apache.org/docs/1.3/mod/mod_mime.html#multipleext
	 *
	 * @param	string	$filename
	 * @return	string
	 */
	protected function _prep_filename($filename)
	{
		if ($this->mod_mime_fix === FALSE OR $this->allowed_types === '*' OR ($ext_pos = strrpos($filename, '.')) === FALSE)
		{
			return $filename;
		}

		$ext = substr($filename, $ext_pos);
		$filename = substr($filename, 0, $ext_pos);
		return str_replace('.', '_', $filename).$ext;
	}

	// --------------------------------------------------------------------

	/**
	 * File MIME type
	 *
	 * Detects the (actual) MIME type of the uploaded file, if possible.
	 * The input array is expected to be $_FILES[$field]
	 *
	 * @param	array	$file
	 * @return	void
	 */
	protected function _file_mime_type($file)
	{
		// We'll need this to validate the MIME info string (e.g. text/plain; charset=us-ascii)
		$regexp = '/^([a-z\-]+\/[a-z0-9\-\.\+]+)(;\s.+)?$/';

		/* Fileinfo extension - most reliable method
		 *
		 * Unfortunately, prior to PHP 5.3 - it's only available as a PECL extension and the
		 * more convenient FILEINFO_MIME_TYPE flag doesn't exist.
		 */
		if (function_exists('finfo_file'))
		{
			$finfo = @finfo_open(FILEINFO_MIME);
			if (is_resource($finfo)) // It is possible that a FALSE value is returned, if there is no magic MIME database file found on the system
			{
				$mime = @finfo_file($finfo, $file['tmp_name']);
				finfo_close($finfo);

				/* According to the comments section of the PHP manual page,
				 * it is possible that this function returns an empty string
				 * for some files (e.g. if they don't exist in the magic MIME database)
				 */
				if (is_string($mime) && preg_match($regexp, $mime, $matches))
				{
					$this->file_type = $matches[1];
					return;
				}
			}
		}

		/* This is an ugly hack, but UNIX-type systems provide a "native" way to detect the file type,
		 * which is still more secure than depending on the value of $_FILES[$field]['type'], and as it
		 * was reported in issue #750 (https://github.com/EllisLab/CodeIgniter/issues/750) - it's better
		 * than mime_content_type() as well, hence the attempts to try calling the command line with
		 * three different functions.
		 *
		 * Notes:
		 *	- the DIRECTORY_SEPARATOR comparison ensures that we're not on a Windows system
		 *	- many system admins would disable the exec(), shell_exec(), popen() and similar functions
		 *	  due to security concerns, hence the function_usable() checks
		 */
		if (DIRECTORY_SEPARATOR !== '\\')
		{
			$cmd = function_exists('escapeshellarg')
				? 'file --brief --mime '.escapeshellarg($file['tmp_name']).' 2>&1'
				: 'file --brief --mime '.$file['tmp_name'].' 2>&1';

			if (function_usable('exec'))
			{
				/* This might look confusing, as $mime is being populated with all of the output when set in the second parameter.
				 * However, we only need the last line, which is the actual return value of exec(), and as such - it overwrites
				 * anything that could already be set for $mime previously. This effectively makes the second parameter a dummy
				 * value, which is only put to allow us to get the return status code.
				 */
				$mime = @exec($cmd, $mime, $return_status);
				if ($return_status === 0 && is_string($mime) && preg_match($regexp, $mime, $matches))
				{
					$this->file_type = $matches[1];
					return;
				}
			}

			if ( ! ini_get('safe_mode') && function_usable('shell_exec'))
			{
				$mime = @shell_exec($cmd);
				if (strlen($mime) > 0)
				{
					$mime = explode("\n", trim($mime));
					if (preg_match($regexp, $mime[(count($mime) - 1)], $matches))
					{
						$this->file_type = $matches[1];
						return;
					}
				}
			}

			if (function_usable('popen'))
			{
				$proc = @popen($cmd, 'r');
				if (is_resource($proc))
				{
					$mime = @fread($proc, 512);
					@pclose($proc);
					if ($mime !== FALSE)
					{
						$mime = explode("\n", trim($mime));
						if (preg_match($regexp, $mime[(count($mime) - 1)], $matches))
						{
							$this->file_type = $matches[1];
							return;
						}
					}
				}
			}
		}

		// Fall back to the deprecated mime_content_type(), if available (still better than $_FILES[$field]['type'])

38% of this comment could be valid code. Did you maybe forget this after debugging?

		if (function_exists('mime_content_type'))
		{
			$this->file_type = @mime_content_type($file['tmp_name']);
			if (strlen($this->file_type) > 0) // It's possible that mime_content_type() returns FALSE or an empty string
			{
				return;
			}
		}

		$this->file_type = $file['type'];
	}

}