[Summary view] [Print] [Text view]

   1  <?php
   2  # MantisBT - A PHP based bugtracking system
   3  
   4  # MantisBT is free software: you can redistribute it and/or modify
   5  # it under the terms of the GNU General Public License as published by
   6  # the Free Software Foundation, either version 2 of the License, or
   7  # (at your option) any later version.
   8  #
   9  # MantisBT is distributed in the hope that it will be useful,
  10  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  # GNU General Public License for more details.
  13  #
  14  # You should have received a copy of the GNU General Public License
  15  # along with MantisBT.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Compression API
  19   *
  20   * @package CoreAPI
  21   * @subpackage CompressionAPI
  22   * @copyright Copyright (C) 2000 - 2002  Kenzaburo Ito - kenito@300baud.org
  23   * @copyright Copyright (C) 2002 - 2011  MantisBT Team - mantisbt-dev@lists.sourceforge.net
  24   * @link http://www.mantisbt.org
  25   *
  26   * @uses constant_inc.php
  27   * @uses php_api.php
  28   * @uses utility_api.php
  29   */
  30  
  31  require_api( 'constant_inc.php' );
  32  require_api( 'php_api.php' );
  33  require_api( 'utility_api.php' );
  34  
  35  /**
  36   * Starts the buffering/compression (only if the compression option is ON)
  37   * This variable is used internally.  It is not used for configuration
  38   * @global bool $g_compression_started
  39   */
  40  $g_compression_started = false;
  41  
  42  /**
  43   * Check if compression handler (ob_gzhandler) should be enabled. Note: this should not be used
  44   * as an indicator of whether output received by a client will be compressed, only whether an
  45   * output handler is used to compress output.
  46   * @return bool
  47   * @access public
  48   */
  49  function compress_handler_is_enabled() {
  50      global $g_compress_html;
  51  
  52      // indicates compression should be disabled for a page. Note: php.ini may still enable zlib.output_compression.
  53      // it may be possible to turn this off through the use of ini_set within that specific page.
  54      if( defined( 'COMPRESSION_DISABLED' ) ) {
  55          return false;
  56      }
  57  
  58      // Dont use config_get here so only dependency is on consant.inc.php in this module
  59      // We only actively compress html if global configuration compress_html is set.
  60      if( ON == $g_compress_html ) {
  61          // both compression handlers require zlib module to be loaded
  62          if( !extension_loaded( 'zlib' ) ) {
  63              return false;
  64          }
  65  
  66          if ( ini_get( 'zlib.output_compression' ) ) {
  67              /* zlib output compression is already enabled - we can't load the gzip output handler */
  68              return false;
  69          }
  70  
  71          // Since php 5.2.10, it's possible to set zlib.output_compression via ini_set.
  72          // This method is preferred over ob_gzhandler
  73          if( php_version_at_least( '5.2.10' ) && ini_get( 'output_handler' ) == '' && function_exists( 'ini_set' ) ) {
  74              ini_set( 'zlib.output_compression', true );
  75              // do it transparently
  76              return false;
  77          }
  78  
  79          // if php.ini does not already use ob_gzhandler by default, return true.
  80          return ( 'ob_gzhandler' != ini_get( 'output_handler' ) );
  81      }
  82  }
  83  
  84  /**
  85   * Start compression handler if required
  86   * @return null
  87   * @access public
  88   */
  89  function compress_start_handler() {
  90      if( compress_handler_is_enabled() ) {
  91          # Before doing anything else, start output buffering so we don't prevent
  92          #  headers from being sent if there's a blank line in an included file
  93          ob_start( 'compress_handler' );
  94      } else if ( ini_get_bool( 'zlib.output_compression' ) == true ) {
  95          if( defined( 'COMPRESSION_DISABLED' ) ) {
  96              return;
  97          }
  98          ob_start();
  99      }
 100  }
 101  
 102  /**
 103   * Output Buffering handler that either compresses the buffer or just.
 104   * returns it, depending on the return value of compress_handler_is_enabled()
 105   * @param string $p_buffer
 106   * @param int $p_mode
 107   * @return string
 108   * @access public
 109   */
 110  function compress_handler( & $p_buffer, $p_mode ) {
 111      global $g_compression_started;
 112      if( $g_compression_started && compress_handler_is_enabled() ) {
 113          return ob_gzhandler( $p_buffer, $p_mode );
 114      } else {
 115          return $p_buffer;
 116      }
 117  }
 118  
 119  /**
 120   * Enable output buffering with compression.
 121   * @return null
 122   * @access public
 123   */
 124  function compress_enable() {
 125      global $g_compression_started;
 126  
 127      $g_compression_started = true;
 128  }
 129  
 130  /**
 131   * Disable output buffering with compression.
 132   * @return null
 133   * @access public
 134   */
 135  function compress_disable() {
 136      global $g_compression_started;
 137  
 138      $g_compression_started = false;
 139  }