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   1  <?php
   2  /**
   3   * Expansion of the PHP execution time limit feature for a function call.
   4   *
   5   * This program is free software; you can redistribute it and/or modify
   6   * it under the terms of the GNU General Public License as published by
   7   * the Free Software Foundation; either version 2 of the License, or
   8   * (at your option) any later version.
   9   *
  10   * This program is distributed in the hope that it will be useful,
  11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13   * GNU General Public License for more details.
  14   *
  15   * You should have received a copy of the GNU General Public License along
  16   * with this program; if not, write to the Free Software Foundation, Inc.,
  17   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18   * http://www.gnu.org/copyleft/gpl.html
  19   *
  20   * @file
  21   */
  22  
  23  /**
  24   * Class to expand PHP execution time for a function call.
  25   * Use this when performing changes that should not be interrupted.
  26   *
  27   * On construction, set_time_limit() is called and set to $seconds.
  28   * If the client aborts the connection, PHP will continue to run.
  29   * When the object goes out of scope, the timer is restarted, with
  30   * the original time limit minus the time the object existed.
  31   */
  32  class ScopedPHPTimeout {
  33      protected $startTime; // float; seconds
  34      protected $oldTimeout; // integer; seconds
  35      protected $oldIgnoreAbort; // boolean
  36  
  37      protected static $stackDepth = 0; // integer
  38      protected static $totalCalls = 0; // integer
  39      protected static $totalElapsed = 0; // float; seconds
  40  
  41      /* Prevent callers in infinite loops from running forever */
  42      const MAX_TOTAL_CALLS = 1000000;
  43      const MAX_TOTAL_TIME = 300; // seconds
  44  
  45      /**
  46       * @param $seconds integer
  47       */
  48  	public function __construct( $seconds ) {
  49          if ( ini_get( 'max_execution_time' ) > 0 ) { // CLI uses 0
  50              if ( self::$totalCalls >= self::MAX_TOTAL_CALLS ) {
  51                  trigger_error( "Maximum invocations of " . __CLASS__ . " exceeded." );
  52              } elseif ( self::$totalElapsed >= self::MAX_TOTAL_TIME ) {
  53                  trigger_error( "Time limit within invocations of " . __CLASS__ . " exceeded." );
  54              } elseif ( self::$stackDepth > 0 ) { // recursion guard
  55                  trigger_error( "Resursive invocation of " . __CLASS__ . " attempted." );
  56              } else {
  57                  $this->oldIgnoreAbort = ignore_user_abort( true );
  58                  $this->oldTimeout = ini_set( 'max_execution_time', $seconds );
  59                  $this->startTime = microtime( true );
  60                  ++self::$stackDepth;
  61                  ++self::$totalCalls; // proof against < 1us scopes
  62              }
  63          }
  64      }
  65  
  66      /**
  67       * Restore the original timeout.
  68       * This does not account for the timer value on __construct().
  69       */
  70  	public function __destruct() {
  71          if ( $this->oldTimeout ) {
  72              $elapsed = microtime( true ) - $this->startTime;
  73              // Note: a limit of 0 is treated as "forever"
  74              set_time_limit( max( 1, $this->oldTimeout - (int)$elapsed ) );
  75              // If each scoped timeout is for less than one second, we end up
  76              // restoring the original timeout without any decrease in value.
  77              // Thus web scripts in an infinite loop can run forever unless we
  78              // take some measures to prevent this. Track total time and calls.
  79              self::$totalElapsed += $elapsed;
  80              --self::$stackDepth;
  81              ignore_user_abort( $this->oldIgnoreAbort );
  82          }
  83      }
  84  }