system/libraries/Upload.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.2.4 or newer
 *
 * NOTICE OF LICENSE
 *
 * Licensed under the Open Software License version 3.0
 *
 * This source file is subject to the Open Software License (OSL 3.0) that is
 * bundled with this package in the files license.txt / license.rst.  It is
 * also available through the world wide web at this URL:
 * http://opensource.org/licenses/OSL-3.0
 * If you did not receive a copy of the license and are unable to obtain it
 * through the world wide web, please send an email to
 * licensing@ellislab.com so we can send you a copy immediately.
 *
 * @package		CodeIgniter
 * @author		EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
 * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
 * @link		http://codeigniter.com
 * @since		Version 1.0
 * @filesource
 */

/**
 * 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 {

	public $max_size		= 0;
	public $max_width		= 0;
	public $max_height		= 0;
	public $max_filename		= 0;
	public $max_filename_increment 	= 100;
	public $allowed_types		= '';
	public $file_temp		= '';
	public $file_name		= '';
	public $orig_name		= '';
	public $file_type		= '';
	public $file_size		= '';
	public $file_ext		= '';
	public $upload_path		= '';
	public $overwrite		= FALSE;
	public $encrypt_name		= FALSE;
	public $is_image		= FALSE;
	public $image_width		= '';
	public $image_height		= '';
	public $image_type		= '';
	public $image_size_str		= '';
	public $error_msg		= array();
	public $mimes			= array();
	public $remove_spaces		= TRUE;
	public $xss_clean		= FALSE;
	public $temp_prefix		= 'temp_file_';
	public $client_name		= '';

	protected $_file_name_override	= '';

	/**
	 * Constructor
	 *
	 * @param	array
	 * @return	void
	 */
	public function __construct($props = array())
	{
		if (count($props) > 0)
		{
			$this->initialize($props);
		}

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

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

	/**
	 * Initialize preferences
	 *
	 * @param	array
	 * @return	void
	 */
	public function initialize($config = array())
	{
		$defaults = array(
					'max_size'			=> 0,
					'max_width'			=> 0,
					'max_height'			=> 0,
					'max_filename'			=> 0,
					'max_filename_increment'	=> 100,
					'allowed_types'			=> '',
					'file_temp'			=> '',
					'file_name'			=> '',
					'orig_name'			=> '',
					'file_type'			=> '',
					'file_size'			=> '',
					'file_ext'			=> '',
					'upload_path'			=> '',
					'overwrite'			=> FALSE,
					'encrypt_name'			=> FALSE,
					'is_image'			=> FALSE,
					'image_width'			=> '',
					'image_height'			=> '',
					'image_type'			=> '',
					'image_size_str'		=> '',
					'error_msg'			=> array(),
					'mimes'				=> array(),
					'remove_spaces'			=> TRUE,
					'xss_clean'			=> FALSE,
					'temp_prefix'			=> 'temp_file_',
					'client_name'			=> ''
				);


		foreach ($defaults as $key => $val)
		{
			if (isset($config[$key]))
			{
				$method = 'set_'.$key;
				if (method_exists($this, $method))
				{
					$this->$method($config[$key]);
				}
				else
				{
					$this->$key = $config[$key];
				}
			}
			else
			{
				$this->$key = $val;
			}
		}

		// 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;
	}

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

	/**
	 * Perform the file upload
	 *
	 * @return	bool
	 */
	public function do_upload($field = 'userfile')
	{
		// Is $_FILES[$field] set? If not, no reason to continue.
		if ( ! isset($_FILES[$field]))
		{
			$this->set_error('upload_no_file_selected');
			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($_FILES[$field]['tmp_name']))
		{
			$error = ( ! isset($_FILES[$field]['error'])) ? 4 : $_FILES[$field]['error'];

			switch ($error)
			{
				case 1:	// UPLOAD_ERR_INI_SIZE
					$this->set_error('upload_file_exceeds_limit');
					break;
				case 2: // UPLOAD_ERR_FORM_SIZE
					$this->set_error('upload_file_exceeds_form_limit');
					break;
				case 3: // UPLOAD_ERR_PARTIAL
					$this->set_error('upload_file_partial');
					break;
				case 4: // UPLOAD_ERR_NO_FILE
					$this->set_error('upload_no_file_selected');
					break;
				case 6: // UPLOAD_ERR_NO_TMP_DIR
					$this->set_error('upload_no_temp_directory');
					break;
				case 7: // UPLOAD_ERR_CANT_WRITE
					$this->set_error('upload_unable_to_write_file');
					break;
				case 8: // UPLOAD_ERR_EXTENSION
					$this->set_error('upload_stopped_by_extension');
					break;
				default:
					$this->set_error('upload_no_file_selected');
					break;
			}

			return FALSE;
		}

		// Set the uploaded data as class variables
		$this->file_temp = $_FILES[$field]['tmp_name'];
		$this->file_size = $_FILES[$field]['size'];
		$this->_file_mime_type($_FILES[$field]);
		$this->file_type = preg_replace('/^(.+?);.*$/', '\\1', $this->file_type);
		$this->file_type = strtolower(trim(stripslashes($this->file_type), '"'));
		$this->file_name = $this->_prep_filename($_FILES[$field]['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');
			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, lets have it!
				$this->file_ext	= $this->get_extension($this->_file_name_override);
			}

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

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

		// Sanitize the file name for security
		$this->file_name = $this->clean_file_name($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 ($this->overwrite === FALSE)
		{
			$this->file_name = $this->set_filename($this->upload_path, $this->file_name);

			if ($this->file_name === FALSE)
			{
				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');
			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');
				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.
	 *
	 * @return	array
	 */
	public function data()
	{
		return 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,
			);
	}

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

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

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

	/**
	 * 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
	 * @param	string
	 * @return	string
	 */
	public function set_filename($path, $filename)
	{
		if ($this->encrypt_name === TRUE)
		{
			mt_srand();
			$filename = md5(uniqid(mt_rand())).$this->file_ext;
		}

		if ( ! 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');
			return FALSE;
		}
		else
		{
			return $new_filename;
		}
	}

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

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

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

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

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

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

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

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

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

	/**
	 * Set Allowed File Types
	 *
	 * @param	string
	 * @return	void
	 */
	public function set_allowed_types($types)
	{
		if ( ! is_array($types) && $types === '*')
		{
			$this->allowed_types = '*';
			return;
		}
		$this->allowed_types = explode('|', $types);
	}

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

	/**
	 * Set Image Properties
	 *
	 * Uses GD to determine the width/height/type of image
	 *
	 * @param	string
	 * @return	void
	 */
	public function set_image_properties($path = '')
	{
		if ( ! $this->is_image())
		{
			return;
		}

		if (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
			}
		}
	}

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

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

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

	/**
	 * 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
	 * @return	bool
	 */
	public function is_allowed_filetype($ignore_mime = FALSE)
	{
		if ($this->allowed_types === '*')
		{
			return TRUE;
		}

		if ( ! is_array($this->allowed_types) OR count($this->allowed_types) === 0)
		{
			$this->set_error('upload_no_file_types');
			return FALSE;
		}

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

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

		// Images get some additional checks
		$image_types = array('gif', 'jpg', 'jpeg', 'png', 'jpe');

		if (in_array($ext, $image_types) && @getimagesize($this->file_temp) === FALSE)
		{
			return FALSE;
		}

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

		$mime = $this->mimes_types($ext);

		if (is_array($mime) && in_array($this->file_type, $mime, TRUE))
		{
			return TRUE;
		}
		elseif ($mime === $this->file_type)
		{
			return TRUE;
		}

		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;
			}
		}

		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');
			return FALSE;
		}

		if (function_exists('realpath') && @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');
			return FALSE;
		}

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

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

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

	/**
	 * Extract the file extension
	 *
	 * @param	string
	 * @return	string
	 */
	public function get_extension($filename)
	{
		$x = explode('.', $filename);
		return (count($x) !== 1) ? '.'.end($x) : '';
	}

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

	/**
	 * Clean the file name for security
	 *
	 * @param	string
	 * @return	string
	 */
	public function clean_file_name($filename)
	{
		$bad = array(
				'<!--', '-->',
				"'", '"',
				'<', '>',
				'&', '$',
				'=',
				';',
				'?',
				'/',
				'!',
				'#',
				'%20',
				'%22',
				'%3c',		// <
				'%253c',	// <
				'%3e',		// >
				'%0e',		// >
				'%28',		// (
				'%29',		// )
				'%2528',	// (
				'%26',		// &
				'%24',		// $
				'%3f',		// ?
				'%3b',		// ;
				'%3d'		// =
			);

		return stripslashes(str_replace($bad, '', $filename));
	}

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

	/**
	 * Limit the File Name Length
	 *
	 * @param	string
	 * @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	void
	 */
	public function do_xss_clean()
	{
		$file = $this->file_temp;

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

		if (function_exists('memory_get_usage') && memory_get_usage() && ini_get('memory_limit') !== '')
		{
			$current = ini_get('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

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

			ini_set('memory_limit', $new_memory); // 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 ( ! preg_match('/<(a|body|head|html|img|plaintext|pre|script|table|title)[\s>]/i', $opening_bytes))
			{
				return TRUE; // its an image, no "triggers" detected in the first 256 bytes, we're good
			}
			else
			{
				return FALSE;
			}
		}

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

		$CI =& get_instance();
		return $CI->security->xss_clean($data, TRUE);
	}

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

	/**
	 * Set an error message
	 *
	 * @param	string
	 * @return	void
	 */
	public function set_error($msg)
	{
		$CI =& get_instance();
		$CI->lang->load('upload');

		if (is_array($msg))
		{
			foreach ($msg as $val)
			{
				$msg = ($CI->lang->line($val) === FALSE) ? $val : $CI->lang->line($val);
				$this->error_msg[] = $msg;
				log_message('error', $msg);
			}
		}
		else
		{
			$msg = ($CI->lang->line($msg) === FALSE) ? $msg : $CI->lang->line($msg);
			$this->error_msg[] = $msg;
			log_message('error', $msg);
		}
	}

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

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

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

	/**
	 * List of Mime Types
	 *
	 * This is a list of mime types. We use it to validate
	 * the "allowed types" set by the developer
	 *
	 * @param	string
	 * @return	string
	 */
	public function mimes_types($mime)
	{
		global $mimes;

		if (count($this->mimes) === 0)
		{
			if (defined('ENVIRONMENT') && is_file(APPPATH.'config/'.ENVIRONMENT.'/mimes.php'))
			{
				include(APPPATH.'config/'.ENVIRONMENT.'/mimes.php');
			}
			elseif (is_file(APPPATH.'config/mimes.php'))
			{
				include(APPPATH.'config/mimes.php');
			}
			else
			{
				return FALSE;
			}

			$this->mimes = $mimes;
		}

		return isset($this->mimes[$mime]) ? $this->mimes[$mime] : FALSE;
	}

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

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

		$parts		= explode('.', $filename);
		$ext		= array_pop($parts);
		$filename	= array_shift($parts);

		foreach ($parts as $part)
		{
			if ( ! in_array(strtolower($part), $this->allowed_types) OR $this->mimes_types(strtolower($part)) === FALSE)
			{
				$filename .= '.'.$part.'_';
			}
			else
			{
				$filename .= '.'.$part;
			}
		}

		return $filename.'.'.$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
	 * @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_exists() checks
		 */
		if (DIRECTORY_SEPARATOR !== '\\')
		{
			$cmd = 'file --brief --mime '.escapeshellarg($file['tmp_name']).' 2>&1';

			if (function_exists('exec'))
			{
				/* This might look confusing, as $mime is being populated with all of the output when set in the second parameter.
				 * However, we only neeed 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 ( (bool) @ini_get('safe_mode') === FALSE && function_exists('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_exists('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'])
		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'];
	}

}

/* End of file Upload.php */
/* Location: ./system/libraries/Upload.php */