source: sourcecode/application/libraries/PHPExcel/Shared/OLERead.php @ 1

<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2014 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 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 * @version    1.8.0, 2014-03-02
 */

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;
                        }
                        else if ( $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;
        }

}