tcpdf_parser.php

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<?php
//============================================================+
// File name   : tcpdf_parser.php
// Version     : 1.0.001
// Begin       : 2011-05-23
// Last Update : 2012-05-03
// Author      : Nicola Asuni - Tecnick.com LTD - Manor Coach House, Church Hill, Aldershot, Hants, GU12 4RQ, UK - www.tecnick.com - info@tecnick.com
// License     : http://www.tecnick.com/pagefiles/tcpdf/LICENSE.TXT GNU-LGPLv3
// -------------------------------------------------------------------
// Copyright (C) 2011-2012  Nicola Asuni - Tecnick.com LTD
//
// This file is part of TCPDF software library.
//
// TCPDF 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 3 of the
// License, or (at your option) any later version.
//
// TCPDF 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 License
// along with TCPDF. If not, see
// <http://www.tecnick.com/pagefiles/tcpdf/LICENSE.TXT>.
//
// See LICENSE.TXT file for more information.
// -------------------------------------------------------------------
//
// Description : This is a PHP class for parsing PDF documents.
//
//============================================================+

// include class for decoding filters
require_once(dirname(__FILE__).'/tcpdf_filters.php');

class TCPDF_PARSER {

     private $pdfdata = '';

     protected $xref = array();

     protected $objects = array();

     private $FilterDecoders;

// -----------------------------------------------------------------------------

     public function __construct($data) {
          if (empty($data)) {
               $this->Error('Empty PDF data.');
          }
          $this->pdfdata = $data;
          // get length
          $pdflen = strlen($this->pdfdata);
          // initialize class for decoding filters
          $this->FilterDecoders = new TCPDF_FILTERS();
          // get xref and trailer data
          $this->xref = $this->getXrefData();
          // parse all document objects
          $this->objects = array();
          foreach ($this->xref['xref'] as $obj => $offset) {
               if (!isset($this->objects[$obj])) {
                    $this->objects[$obj] = $this->getIndirectObject($obj, $offset, true);
               }
          }
          // release some memory
          unset($this->pdfdata);
          $this->pdfdata = '';
     }

     public function getParsedData() {
          return array($this->xref, $this->objects);
     }

     protected function getXrefData($offset=0, $xref=array()) {
          if ($offset == 0) {
               // find last startxref
               if (preg_match_all('/[\r\n]startxref[\s]*[\r\n]+([0-9]+)[\s]*[\r\n]+%%EOF/i', $this->pdfdata, $matches, PREG_SET_ORDER, $offset) == 0) {
                    $this->Error('Unable to find startxref');
               }
               $matches = array_pop($matches);
               $startxref = $matches[1];
          } else {
               // get the first xref at the specified offset
               if (preg_match('/[\r\n]startxref[\s]*[\r\n]+([0-9]+)[\s]*[\r\n]+%%EOF/i', $this->pdfdata, $matches, PREG_OFFSET_CAPTURE, $offset) == 0) {
                    $this->Error('Unable to find startxref');
               }
               $startxref = $matches[1][0];
          }
          // check xref position
          if (strpos($this->pdfdata, 'xref', $startxref) != $startxref) {
               $this->Error('Unable to find xref');
          }
          // extract xref data (object indexes and offsets)
          $xoffset = $startxref + 5;
          // initialize object number
          $obj_num = 0;
          $offset = $xoffset;
          while (preg_match('/^([0-9]+)[\s]([0-9]+)[\s]?([nf]?)/im', $this->pdfdata, $matches, PREG_OFFSET_CAPTURE, $offset) > 0) {
               $offset = (strlen($matches[0][0]) + $matches[0][1]);
               if ($matches[3][0] == 'n') {
                    // create unique object index: [object number]_[generation number]
                    $index = $obj_num.'_'.intval($matches[2][0]);
                    // check if object already exist
                    if (!isset($xref['xref'][$index])) {
                         // store object offset position
                         $xref['xref'][$index] = intval($matches[1][0]);
                    }
                    ++$obj_num;
                    $offset += 2;
               } elseif ($matches[3][0] == 'f') {
                    ++$obj_num;
                    $offset += 2;
               } else {
                    // object number (index)
                    $obj_num = intval($matches[1][0]);
               }
          }
          // get trailer data
          if (preg_match('/trailer[\s]*<<(.*)>>[\s]*[\r\n]+startxref[\s]*[\r\n]+/isU', $this->pdfdata, $matches, PREG_OFFSET_CAPTURE, $xoffset) > 0) {
               $trailer_data = $matches[1][0];
               if (!isset($xref['trailer'])) {
                    // get only the last updated version
                    $xref['trailer'] = array();
                    // parse trailer_data
                    if (preg_match('/Size[\s]+([0-9]+)/i', $trailer_data, $matches) > 0) {
                         $xref['trailer']['size'] = intval($matches[1]);
                    }
                    if (preg_match('/Root[\s]+([0-9]+)[\s]+([0-9]+)[\s]+R/i', $trailer_data, $matches) > 0) {
                         $xref['trailer']['root'] = intval($matches[1]).'_'.intval($matches[2]);
                    }
                    if (preg_match('/Encrypt[\s]+([0-9]+)[\s]+([0-9]+)[\s]+R/i', $trailer_data, $matches) > 0) {
                         $xref['trailer']['encrypt'] = intval($matches[1]).'_'.intval($matches[2]);
                    }
                    if (preg_match('/Info[\s]+([0-9]+)[\s]+([0-9]+)[\s]+R/i', $trailer_data, $matches) > 0) {
                         $xref['trailer']['info'] = intval($matches[1]).'_'.intval($matches[2]);
                    }
                    if (preg_match('/ID[\s]*[\[][\s]*[<]([^>]*)[>][\s]*[<]([^>]*)[>]/i', $trailer_data, $matches) > 0) {
                         $xref['trailer']['id'] = array();
                         $xref['trailer']['id'][0] = $matches[1];
                         $xref['trailer']['id'][1] = $matches[2];
                    }
               }
               if (preg_match('/Prev[\s]+([0-9]+)/i', $trailer_data, $matches) > 0) {
                    // get previous xref
                    $xref = $this->getXrefData(intval($matches[1]), $xref);
               }
          } else {
               $this->Error('Unable to find trailer');
          }
          return $xref;
     }

     protected function getRawObject($offset=0) {
          $objtype = ''; // object type to be returned
          $objval = ''; // object value to be returned
          // skip initial white space chars: \x00 null (NUL), \x09 horizontal tab (HT), \x0A line feed (LF), \x0C form feed (FF), \x0D carriage return (CR), \x20 space (SP)
          $offset += strspn($this->pdfdata, "\x00\x09\x0a\x0c\x0d\x20", $offset);
          // get first char
          $char = $this->pdfdata{$offset};
          // get object type
          switch ($char) {
               case '%': { // \x25 PERCENT SIGN
                    // skip comment and search for next token
                    $next = strcspn($this->pdfdata, "\r\n", $offset);
                    if ($next > 0) {
                         $offset += $next;
                         return $this->getRawObject($this->pdfdata, $offset);
                    }
                    break;
               }
               case '/': { // \x2F SOLIDUS
                    // name object
                    $objtype = $char;
                    ++$offset;
                    if (preg_match('/^([^\x00\x09\x0a\x0c\x0d\x20\s\x28\x29\x3c\x3e\x5b\x5d\x7b\x7d\x2f\x25]+)/', substr($this->pdfdata, $offset, 256), $matches) == 1) {
                         $objval = $matches[1]; // unescaped value
                         $offset += strlen($objval);
                    }
                    break;
               }
               case '(':   // \x28 LEFT PARENTHESIS
               case ')': { // \x29 RIGHT PARENTHESIS
                    // literal string object
                    $objtype = $char;
                    ++$offset;
                    $strpos = $offset;
                    if ($char == '(') {
                         $open_bracket = 1;
                         while ($open_bracket > 0) {
                              if (!isset($this->pdfdata{$strpos})) {
                                   break;
                              }
                              $ch = $this->pdfdata{$strpos};
                              switch ($ch) {
                                   case '\\': { // REVERSE SOLIDUS (5Ch) (Backslash)
                                        // skip next character
                                        ++$strpos;
                                        break;
                                   }
                                   case '(': { // LEFT PARENHESIS (28h)
                                        ++$open_bracket;
                                        break;
                                   }
                                   case ')': { // RIGHT PARENTHESIS (29h)
                                        --$open_bracket;
                                        break;
                                   }
                              }
                              ++$strpos;
                         }
                         $objval = substr($this->pdfdata, $offset, ($strpos - $offset - 1));
                         $offset = $strpos;
                    }
                    break;
               }
               case '[':   // \x5B LEFT SQUARE BRACKET
               case ']': { // \x5D RIGHT SQUARE BRACKET
                    // array object
                    $objtype = $char;
                    ++$offset;
                    if ($char == '[') {
                         // get array content
                         $objval = array();
                         do {
                              // get element
                              $element = $this->getRawObject($offset);
                              $offset = $element[2];
                              $objval[] = $element;
                         } while ($element[0] != ']');
                         // remove closing delimiter
                         array_pop($objval);
                    }
                    break;
               }
               case '<':   // \x3C LESS-THAN SIGN
               case '>': { // \x3E GREATER-THAN SIGN
                    if (isset($this->pdfdata{($offset + 1)}) AND ($this->pdfdata{($offset + 1)} == $char)) {
                         // dictionary object
                         $objtype = $char.$char;
                         $offset += 2;
                         if ($char == '<') {
                              // get array content
                              $objval = array();
                              do {
                                   // get element
                                   $element = $this->getRawObject($offset);
                                   $offset = $element[2];
                                   $objval[] = $element;
                              } while ($element[0] != '>>');
                              // remove closing delimiter
                              array_pop($objval);
                         }
                    } else {
                         // hexadecimal string object
                         $objtype = $char;
                         ++$offset;
                         if (($char == '<') AND (preg_match('/^([0-9A-Fa-f]+)[>]/iU', substr($this->pdfdata, $offset), $matches) == 1)) {
                              $objval = $matches[1];
                              $offset += strlen($matches[0]);
                         }
                    }
                    break;
               }
               default: {
                    if (substr($this->pdfdata, $offset, 6) == 'endobj') {
                         // indirect object
                         $objtype = 'endobj';
                         $offset += 6;
                    } elseif (substr($this->pdfdata, $offset, 4) == 'null') {
                         // null object
                         $objtype = 'null';
                         $offset += 4;
                         $objval = 'null';
                    } elseif (substr($this->pdfdata, $offset, 4) == 'true') {
                         // boolean true object
                         $objtype = 'boolean';
                         $offset += 4;
                         $objval = 'true';
                    } elseif (substr($this->pdfdata, $offset, 5) == 'false') {
                         // boolean false object
                         $objtype = 'boolean';
                         $offset += 5;
                         $objval = 'false';
                    } elseif (substr($this->pdfdata, $offset, 6) == 'stream') {
                         // start stream object
                         $objtype = 'stream';
                         $offset += 6;
                         if (preg_match('/^[\r\n]+(.*)[\r\n]*endstream/isU', substr($this->pdfdata, $offset), $matches) == 1) {
                              $objval = $matches[1];
                              $offset += strlen($matches[0]);
                         }
                    } elseif (substr($this->pdfdata, $offset, 9) == 'endstream') {
                         // end stream object
                         $objtype = 'endstream';
                         $offset += 9;
                    } elseif (preg_match('/^([0-9]+)[\s]+([0-9]+)[\s]+R/iU', substr($this->pdfdata, $offset, 33), $matches) == 1) {
                         // indirect object reference
                         $objtype = 'ojbref';
                         $offset += strlen($matches[0]);
                         $objval = intval($matches[1]).'_'.intval($matches[2]);
                    } elseif (preg_match('/^([0-9]+)[\s]+([0-9]+)[\s]+obj/iU', substr($this->pdfdata, $offset, 33), $matches) == 1) {
                         // object start
                         $objtype = 'ojb';
                         $objval = intval($matches[1]).'_'.intval($matches[2]);
                         $offset += strlen ($matches[0]);
                    } elseif (($numlen = strspn($this->pdfdata, '+-.0123456789', $offset)) > 0) {
                         // numeric object
                         $objtype = 'numeric';
                         $objval = substr($this->pdfdata, $offset, $numlen);
                         $offset += $numlen;
                    }
                    break;
               }
          }
          return array($objtype, $objval, $offset);
     }

     protected function getIndirectObject($obj_ref, $offset=0, $decoding=true) {
          $obj = explode('_', $obj_ref);
          if (($obj === false) OR (count($obj) != 2)) {
               $this->Error('Invalid object reference: '.$obj);
               return;
          }
          $objref = $obj[0].' '.$obj[1].' obj';
          if (strpos($this->pdfdata, $objref, $offset) != $offset) {
               // an indirect reference to an undefined object shall be considered a reference to the null object
               return array('null', 'null', $offset);
          }
          // starting position of object content
          $offset += strlen($objref);
          // get array of object content
          $objdata = array();
          $i = 0; // object main index
          do {
               // get element
               $element = $this->getRawObject($offset);
               $offset = $element[2];
               // decode stream using stream's dictionary information
               if ($decoding AND ($element[0] == 'stream') AND (isset($objdata[($i - 1)][0])) AND ($objdata[($i - 1)][0] == '<<')) {
                    $element[3] = $this->decodeStream($objdata[($i - 1)][1], substr($element[1], 1));
               }
               $objdata[$i] = $element;
               ++$i;
          } while ($element[0] != 'endobj');
          // remove closing delimiter
          array_pop($objdata);
          // return raw object content
          return $objdata;
     }

     protected function getObjectVal($obj) {
          if ($obj[0] == 'objref') {
               // reference to indirect object
               if (isset($this->objects[$obj[1]])) {
                    // this object has been already parsed
                    return $this->objects[$obj[1]];
               } elseif (isset($this->xref[$obj[1]])) {
                    // parse new object
                    $this->objects[$obj[1]] = $this->getIndirectObject($obj[1], $this->xref[$obj[1]], false);
                    return $this->objects[$obj[1]];
               }
          }
          return $obj;
     }

     protected function decodeStream($sdic, $stream) {
          // get stream lenght and filters
          $slength = strlen($stream);
          $filters = array();
          foreach ($sdic as $k => $v) {
               if ($v[0] == '/') {
                    if (($v[1] == 'Length') AND (isset($sdic[($k + 1)])) AND ($sdic[($k + 1)][0] == 'numeric')) {
                         // get declared stream lenght
                         $declength = intval($sdic[($k + 1)][1]);
                         if ($declength < $slength) {
                              $stream = substr($stream, 0, $declength);
                              $slength = $declength;
                         }
                    } elseif (($v[1] == 'Filter') AND (isset($sdic[($k + 1)]))) {
                         // resolve indirect object
                         $objval = $this->getObjectVal($sdic[($k + 1)]);
                         if ($objval[0] == '/') {
                              // single filter
                              $filters[] = $objval[1];
                         } elseif ($objval[0] == '[') {
                              // array of filters
                              foreach ($objval[1] as $flt) {
                                   if ($flt[0] == '/') {
                                        $filters[] = $flt[1];
                                   }
                              }
                         }
                    }
               }
          }
          // decode the stream
          $remaining_filters = array();
          foreach ($filters as $filter) {
               if (in_array($filter, $this->FilterDecoders->getAvailableFilters())) {
                    $stream = $this->FilterDecoders->decodeFilter($filter, $stream);
               } else {
                    // add missing filter to array
                    $remaining_filters[] = $filter;
               }
          }
          return array($stream, $remaining_filters);
     }

     public function Error($msg) {
          // exit program and print error
          die('<strong>TCPDF_PARSER ERROR: </strong>'.$msg);
     }

} // END OF TCPDF_PARSER CLASS

//============================================================+
// END OF FILE
//============================================================+