phpBB/includes/core/system.php

   1 <?php
   2 /**
   3 *
   4 * @package core
   5 * @version $Id$
   6 * @copyright (c) 2008 phpBB Group
   7 * @license http://opensource.org/licenses/gpl-license.php GNU Public License
   8 *
   9 */
  10
  11 /**
  12 * @ignore
  13 */
  14 if (!defined('IN_PHPBB'))
  15 {
  16         exit();
  17 }
  18
  19 /**
  20 * System-specific methods. For example chmod(), unlink()...
  21 *
  22 * @package core
  23 */
  24 class phpbb_system extends phpbb_plugin_support
  25 {
  26         /**
  27         * @var array required phpBB objects
  28         */
  29         public $phpbb_required = array();
  30
  31         /**
  32         * @var array Optional phpBB objects
  33         */
  34         public $phpbb_optional = array();
  35
  36         /**
  37         * @var array Holding some information for chmod()
  38         */
  39         private $chmod_info = array();
  40
  41         /**
  42         * Method for chmodding directories and files for internal use.
  43         *
  44         * This function determines owner and group whom the file belongs to and user and group of PHP and then set safest possible file permissions.
  45         * The function determines owner and group from common.php file and sets the same to the provided file.
  46         * The function uses bit fields to build the permissions.
  47         * The function sets the appropiate execute bit on directories.
  48         *
  49         * Supported constants representing bit fields are:
  50         *
  51         * phpbb::CHMOD_ALL - all permissions (7)
  52         * phpbb::CHMOD_READ - read permission (4)
  53         * phpbb::CHMOD_WRITE - write permission (2)
  54         * phpbb::CHMOD_EXECUTE - execute permission (1)
  55         *
  56         * NOTE: The function uses POSIX extension and fileowner()/filegroup() functions. If any of them is disabled, this function tries to build proper permissions, by calling is_readable() and is_writable() functions.
  57         *
  58         * @param string $filename       The file/directory to be chmodded
  59         * @param int    $perms          Permissions to set
  60         *
  61         * @return bool  true on success, otherwise false
  62         * @author faw, phpBB Group
  63         * @access public
  64         */
  65         public function chmod($filename, $perms = phpbb::CHMOD_READ)
  66         {
  67                 // Return if the file no longer exists.
  68                 if (!file_exists($filename))
  69                 {
  70                         return false;
  71                 }
  72
  73                 // Determine some common vars
  74                 if (empty($this->chmod_info))
  75                 {
  76                         if (!function_exists('fileowner') || !function_exists('filegroup'))
  77                         {
  78                                 // No need to further determine owner/group - it is unknown
  79                                 $this->chmod_info['process'] = false;
  80                         }
  81                         else
  82                         {
  83                                 // Determine owner/group of common.php file and the filename we want to change here
  84                                 $common_php_owner = fileowner(PHPBB_ROOT_PATH . 'common.' . PHP_EXT);
  85                                 $common_php_group = filegroup(PHPBB_ROOT_PATH . 'common.' . PHP_EXT);
  86
  87                                 // And the owner and the groups PHP is running under.
  88                                 $php_uid = (function_exists('posix_getuid')) ? @posix_getuid() : false;
  89                                 $php_gids = (function_exists('posix_getgroups')) ? @posix_getgroups() : false;
  90
  91                                 if (!$php_uid || empty($php_gids) || !$common_php_owner || !$common_php_group)
  92                                 {
  93                                         $this->chmod_info['process'] = false;
  94                                 }
  95                                 else
  96                                 {
  97                                         $this->chmod_info = array(
  98                                                 'process'               => true,
  99                                                 'common_owner'  => $common_php_owner,
 100                                                 'common_group'  => $common_php_group,
 101                                                 'php_uid'               => $php_uid,
 102                                                 'php_gids'              => $php_gids,
 103                                         );
 104                                 }
 105                         }
 106                 }
 107
 108                 if ($this->chmod_info['process'])
 109                 {
 110                         // Change owner
 111                         if (@chown($filename, $this->chmod_info['common_owner']))
 112                         {
 113                                 clearstatcache();
 114                                 $file_uid = fileowner($filename);
 115                         }
 116
 117                         // Change group
 118                         if (@chgrp($filename, $this->chmod_info['common_group']))
 119                         {
 120                                 clearstatcache();
 121                                 $file_gid = filegroup($filename);
 122                         }
 123
 124                         // If the file_uid/gid now match the one from common.php we can process further, else we are not able to change something
 125                         if ($file_uid != $this->chmod_info['common_owner'] || $file_gid != $this->chmod_info['common_group'])
 126                         {
 127                                 $this->chmod_info['process'] = false;
 128                         }
 129                 }
 130
 131                 // Still able to process?
 132                 if ($this->chmod_info['process'])
 133                 {
 134                         if ($file_uid == $this->chmod_info['php_uid'])
 135                         {
 136                                 $php = 'owner';
 137                         }
 138                         else if (in_array($file_gid, $this->chmod_info['php_gids']))
 139                         {
 140                                 $php = 'group';
 141                         }
 142                         else
 143                         {
 144                                 // Since we are setting the everyone bit anyway, no need to do expensive operations
 145                                 $this->chmod_info['process'] = false;
 146                         }
 147                 }
 148
 149                 // We are not able to determine or change something
 150                 if (!$this->chmod_info['process'])
 151                 {
 152                         $php = 'other';
 153                 }
 154
 155                 // Owner always has read/write permission
 156                 $owner = phpbb::CHMOD_READ | phpbb::CHMOD_WRITE;
 157                 if (is_dir($filename))
 158                 {
 159                         $owner |= phpbb::CHMOD_EXECUTE;
 160
 161                         // Only add execute bit to the permission if the dir needs to be readable
 162                         if ($perms & phpbb::CHMOD_READ)
 163                         {
 164                                 $perms |= phpbb::CHMOD_EXECUTE;
 165                         }
 166                 }
 167
 168                 switch ($php)
 169                 {
 170                         case 'owner':
 171                                 $result = @chmod($filename, ($owner << 6) + (0 << 3) + (0 << 0));
 172
 173                                 clearstatcache();
 174
 175                                 if (!is_null($php) || (is_readable($filename) && is_writable($filename)))
 176                                 {
 177                                         break;
 178                                 }
 179
 180                         case 'group':
 181                                 $result = @chmod($filename, ($owner << 6) + ($perms << 3) + (0 << 0));
 182
 183                                 clearstatcache();
 184
 185                                 if (!is_null($php) || ((!($perms & phpbb::CHMOD_READ) || is_readable($filename)) && (!($perms & phpbb::CHMOD_WRITE) || is_writable($filename))))
 186                                 {
 187                                         break;
 188                                 }
 189
 190                         case 'other':
 191                                 $result = @chmod($filename, ($owner << 6) + ($perms << 3) + ($perms << 0));
 192
 193                                 clearstatcache();
 194
 195                                 if (!is_null($php) || ((!($perms & phpbb::CHMOD_READ) || is_readable($filename)) && (!($perms & phpbb::CHMOD_WRITE) || is_writable($filename))))
 196                                 {
 197                                         break;
 198                                 }
 199
 200                         default:
 201                                 return false;
 202                         break;
 203                 }
 204
 205                 return $result;
 206         }
 207
 208 }
 209
 210 ?>