<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2015 PHPExcel
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category   PHPExcel
 * @package    PHPExcel_Shared
 * @copyright  Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 * @version    ##VERSION##, ##DATE##
 */
defined ( 'IDENTIFIER_OLE' ) || define ( 'IDENTIFIER_OLE', pack ( 'CCCCCCCC', 0xd0, 0xcf, 0x11, 0xe0, 0xa1, 0xb1, 0x1a, 0xe1 ) );
class PHPExcel_Shared_OLERead
{
  private $data = '';
  
  // OLE identifier
  const IDENTIFIER_OLE = IDENTIFIER_OLE;
  
  // Size of a sector = 512 bytes
  const BIG_BLOCK_SIZE = 0x200;
  
  // Size of a short sector = 64 bytes
  const SMALL_BLOCK_SIZE = 0x40;
  
  // Size of a directory entry always = 128 bytes
  const PROPERTY_STORAGE_BLOCK_SIZE = 0x80;
  
  // Minimum size of a standard stream = 4096 bytes, streams smaller than this are stored as short streams
  const SMALL_BLOCK_THRESHOLD = 0x1000;
  
  // header offsets
  const NUM_BIG_BLOCK_DEPOT_BLOCKS_POS = 0x2c;
  const ROOT_START_BLOCK_POS = 0x30;
  const SMALL_BLOCK_DEPOT_BLOCK_POS = 0x3c;
  const EXTENSION_BLOCK_POS = 0x44;
  const NUM_EXTENSION_BLOCK_POS = 0x48;
  const BIG_BLOCK_DEPOT_BLOCKS_POS = 0x4c;
  
  // property storage offsets (directory offsets)
  const SIZE_OF_NAME_POS = 0x40;
  const TYPE_POS = 0x42;
  const START_BLOCK_POS = 0x74;
  const SIZE_POS = 0x78;
  public $wrkbook = null;
  public $summaryInformation = null;
  public $documentSummaryInformation = null;
  
  /**
   * Read the file
   *
   * @param $sFileName string
   *          Filename
   * @throws PHPExcel_Reader_Exception
   */
  public function read($sFileName)
  {
    // Check if file exists and is readable
    if (! is_readable ( $sFileName ))
    {
      throw new PHPExcel_Reader_Exception ( "Could not open " . $sFileName . " for reading! File does not exist, or it is not readable." );
    }
    
    // Get the file identifier
    // Don't bother reading the whole file until we know it's a valid OLE file
    $this->data = file_get_contents ( $sFileName, false, null, 0, 8 );
    
    // Check OLE identifier
    if ($this->data != self::IDENTIFIER_OLE)
    {
      throw new PHPExcel_Reader_Exception ( 'The filename ' . $sFileName . ' is not recognised as an OLE file' );
    }
    
    // Get the file data
    $this->data = file_get_contents ( $sFileName );
    
    // Total number of sectors used for the SAT
    $this->numBigBlockDepotBlocks = self::getInt4d ( $this->data, self::NUM_BIG_BLOCK_DEPOT_BLOCKS_POS );
    
    // SecID of the first sector of the directory stream
    $this->rootStartBlock = self::getInt4d ( $this->data, self::ROOT_START_BLOCK_POS );
    
    // SecID of the first sector of the SSAT (or -2 if not extant)
    $this->sbdStartBlock = self::getInt4d ( $this->data, self::SMALL_BLOCK_DEPOT_BLOCK_POS );
    
    // SecID of the first sector of the MSAT (or -2 if no additional sectors are used)
    $this->extensionBlock = self::getInt4d ( $this->data, self::EXTENSION_BLOCK_POS );
    
    // Total number of sectors used by MSAT
    $this->numExtensionBlocks = self::getInt4d ( $this->data, self::NUM_EXTENSION_BLOCK_POS );
    
    $bigBlockDepotBlocks = array ();
    $pos = self::BIG_BLOCK_DEPOT_BLOCKS_POS;
    
    $bbdBlocks = $this->numBigBlockDepotBlocks;
    
    if ($this->numExtensionBlocks != 0)
    {
      $bbdBlocks = (self::BIG_BLOCK_SIZE - self::BIG_BLOCK_DEPOT_BLOCKS_POS) / 4;
    }
    
    for($i = 0; $i < $bbdBlocks; ++ $i)
    {
      $bigBlockDepotBlocks [$i] = self::getInt4d ( $this->data, $pos );
      $pos += 4;
    }
    
    for($j = 0; $j < $this->numExtensionBlocks; ++ $j)
    {
      $pos = ($this->extensionBlock + 1) * self::BIG_BLOCK_SIZE;
      $blocksToRead = min ( $this->numBigBlockDepotBlocks - $bbdBlocks, self::BIG_BLOCK_SIZE / 4 - 1 );
      
      for($i = $bbdBlocks; $i < $bbdBlocks + $blocksToRead; ++ $i)
      {
        $bigBlockDepotBlocks [$i] = self::getInt4d ( $this->data, $pos );
        $pos += 4;
      }
      
      $bbdBlocks += $blocksToRead;
      if ($bbdBlocks < $this->numBigBlockDepotBlocks)
      {
        $this->extensionBlock = self::getInt4d ( $this->data, $pos );
      }
    }
    
    $pos = 0;
    $this->bigBlockChain = '';
    $bbs = self::BIG_BLOCK_SIZE / 4;
    for($i = 0; $i < $this->numBigBlockDepotBlocks; ++ $i)
    {
      $pos = ($bigBlockDepotBlocks [$i] + 1) * self::BIG_BLOCK_SIZE;
      
      $this->bigBlockChain .= substr ( $this->data, $pos, 4 * $bbs );
      $pos += 4 * $bbs;
    }
    
    $pos = 0;
    $sbdBlock = $this->sbdStartBlock;
    $this->smallBlockChain = '';
    while ( $sbdBlock != - 2 )
    {
      $pos = ($sbdBlock + 1) * self::BIG_BLOCK_SIZE;
      
      $this->smallBlockChain .= substr ( $this->data, $pos, 4 * $bbs );
      $pos += 4 * $bbs;
      
      $sbdBlock = self::getInt4d ( $this->bigBlockChain, $sbdBlock * 4 );
    }
    
    // read the directory stream
    $block = $this->rootStartBlock;
    $this->entry = $this->_readData ( $block );
    
    $this->readPropertySets ();
  }
  
  /**
   * Extract binary stream data
   *
   * @return string
   */
  public function getStream($stream)
  {
    if ($stream === null)
    {
      return null;
    }
    
    $streamData = '';
    
    if ($this->props [$stream] ['size'] < self::SMALL_BLOCK_THRESHOLD)
    {
      $rootdata = $this->_readData ( $this->props [$this->rootentry] ['startBlock'] );
      
      $block = $this->props [$stream] ['startBlock'];
      
      while ( $block != - 2 )
      {
        $pos = $block * self::SMALL_BLOCK_SIZE;
        $streamData .= substr ( $rootdata, $pos, self::SMALL_BLOCK_SIZE );
        
        $block = self::getInt4d ( $this->smallBlockChain, $block * 4 );
      }
      
      return $streamData;
    }
    else
    {
      $numBlocks = $this->props [$stream] ['size'] / self::BIG_BLOCK_SIZE;
      if ($this->props [$stream] ['size'] % self::BIG_BLOCK_SIZE != 0)
      {
        ++ $numBlocks;
      }
      
      if ($numBlocks == 0)
      {
        return '';
      }
      
      $block = $this->props [$stream] ['startBlock'];
      
      while ( $block != - 2 )
      {
        $pos = ($block + 1) * self::BIG_BLOCK_SIZE;
        $streamData .= substr ( $this->data, $pos, self::BIG_BLOCK_SIZE );
        $block = self::getInt4d ( $this->bigBlockChain, $block * 4 );
      }
      
      return $streamData;
    }
  }
  
  /**
   * Read a standard stream (by joining sectors using information from SAT)
   *
   * @param int $bl
   *          Sector ID where the stream starts
   * @return string Data for standard stream
   */
  private function _readData($bl)
  {
    $block = $bl;
    $data = '';
    
    while ( $block != - 2 )
    {
      $pos = ($block + 1) * self::BIG_BLOCK_SIZE;
      $data .= substr ( $this->data, $pos, self::BIG_BLOCK_SIZE );
      $block = self::getInt4d ( $this->bigBlockChain, $block * 4 );
    }
    return $data;
  }
  
  /**
   * Read entries in the directory stream.
   */
  private function readPropertySets()
  {
    $offset = 0;
    
    // loop through entires, each entry is 128 bytes
    $entryLen = strlen ( $this->entry );
    while ( $offset < $entryLen )
    {
      // entry data (128 bytes)
      $d = substr ( $this->entry, $offset, self::PROPERTY_STORAGE_BLOCK_SIZE );
      
      // size in bytes of name
      $nameSize = ord ( $d [self::SIZE_OF_NAME_POS] ) | (ord ( $d [self::SIZE_OF_NAME_POS + 1] ) << 8);
      
      // type of entry
      $type = ord ( $d [self::TYPE_POS] );
      
      // sectorID of first sector or short sector, if this entry refers to a stream (the case with workbook)
      // sectorID of first sector of the short-stream container stream, if this entry is root entry
      $startBlock = self::getInt4d ( $d, self::START_BLOCK_POS );
      
      $size = self::getInt4d ( $d, self::SIZE_POS );
      
      $name = str_replace ( "\x00", "", substr ( $d, 0, $nameSize ) );
      
      $this->props [] = array (
          'name' => $name,
          'type' => $type,
          'startBlock' => $startBlock,
          'size' => $size 
      );
      
      // tmp helper to simplify checks
      $upName = strtoupper ( $name );
      
      // Workbook directory entry (BIFF5 uses Book, BIFF8 uses Workbook)
      if (($upName === 'WORKBOOK') || ($upName === 'BOOK'))
      {
        $this->wrkbook = count ( $this->props ) - 1;
      }
      elseif ($upName === 'ROOT ENTRY' || $upName === 'R')
      {
        // Root entry
        $this->rootentry = count ( $this->props ) - 1;
      }
      
      // Summary information
      if ($name == chr ( 5 ) . 'SummaryInformation')
      {
        // echo 'Summary Information<br />';
        $this->summaryInformation = count ( $this->props ) - 1;
      }
      
      // Additional Document Summary information
      if ($name == chr ( 5 ) . 'DocumentSummaryInformation')
      {
        // echo 'Document Summary Information<br />';
        $this->documentSummaryInformation = count ( $this->props ) - 1;
      }
      
      $offset += self::PROPERTY_STORAGE_BLOCK_SIZE;
    }
  }
  
  /**
   * Read 4 bytes of data at specified position
   *
   * @param string $data          
   * @param int $pos          
   * @return int
   */
  private static function getInt4d($data, $pos)
  {
    // FIX: represent numbers correctly on 64-bit system
    // http://sourceforge.net/tracker/index.php?func=detail&aid=1487372&group_id=99160&atid=623334
    // Hacked by Andreas Rehm 2006 to ensure correct result of the <<24 block on 32 and 64bit systems
    $_or_24 = ord ( $data [$pos + 3] );
    if ($_or_24 >= 128)
    {
      // negative number
      $_ord_24 = - abs ( (256 - $_or_24) << 24 );
    }
    else
    {
      $_ord_24 = ($_or_24 & 127) << 24;
    }
    return ord ( $data [$pos] ) | (ord ( $data [$pos + 1] ) << 8) | (ord ( $data [$pos + 2] ) << 16) | $_ord_24;
  }
}
