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pdf_parser.php
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Laurent Destailleur authoredLaurent Destailleur authored
pdf_parser.php 23.14 KiB
<?php
//
// FPDI - Version 1.4.1
//
// Copyright 2004-2011 Setasign - Jan Slabon
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
if (!defined ('PDF_TYPE_NULL'))
define ('PDF_TYPE_NULL', 0);
if (!defined ('PDF_TYPE_NUMERIC'))
define ('PDF_TYPE_NUMERIC', 1);
if (!defined ('PDF_TYPE_TOKEN'))
define ('PDF_TYPE_TOKEN', 2);
if (!defined ('PDF_TYPE_HEX'))
define ('PDF_TYPE_HEX', 3);
if (!defined ('PDF_TYPE_STRING'))
define ('PDF_TYPE_STRING', 4);
if (!defined ('PDF_TYPE_DICTIONARY'))
define ('PDF_TYPE_DICTIONARY', 5);
if (!defined ('PDF_TYPE_ARRAY'))
define ('PDF_TYPE_ARRAY', 6);
if (!defined ('PDF_TYPE_OBJDEC'))
define ('PDF_TYPE_OBJDEC', 7);
if (!defined ('PDF_TYPE_OBJREF'))
define ('PDF_TYPE_OBJREF', 8);
if (!defined ('PDF_TYPE_OBJECT'))
define ('PDF_TYPE_OBJECT', 9);
if (!defined ('PDF_TYPE_STREAM'))
define ('PDF_TYPE_STREAM', 10);
if (!defined ('PDF_TYPE_BOOLEAN'))
define ('PDF_TYPE_BOOLEAN', 11);
if (!defined ('PDF_TYPE_REAL'))
define ('PDF_TYPE_REAL', 12);
require_once('pdf_context.php');
if (!class_exists('pdf_parser', false)) {
class pdf_parser {
/**
* Filename
* @var string
*/
var $filename;
/**
* File resource
* @var resource
*/
var $f;
/**
* PDF Context
* @var object pdf_context-Instance
*/
var $c;
/**
* xref-Data
* @var array
*/
var $xref;
/**
* root-Object
* @var array
*/
var $root;
/**
* PDF version of the loaded document
* @var string
*/
var $pdfVersion;
/**
* For reading encrypted documents and xref/objectstreams are in use
*
* @var boolean
*/
var $readPlain = true;
/**
* Constructor
*
* @param string $filename Source-Filename
*/
function pdf_parser($filename) {
$this->filename = $filename;
$this->f = @fopen($this->filename, 'rb');
if (!$this->f)
$this->error(sprintf('Cannot open %s !', $filename));
$this->getPDFVersion();
$this->c = new pdf_context($this->f);
// Read xref-Data
$this->xref = array();
$this->pdf_read_xref($this->xref, $this->pdf_find_xref());
// Check for Encryption
$this->getEncryption();
// Read root
$this->pdf_read_root();
}
/**
* Close the opened file
*/
function closeFile() {
if (isset($this->f) && is_resource($this->f)) {
fclose($this->f);
unset($this->f);
}
}
/**
* Print Error and die
*
* @param string $msg Error-Message
*/
function error($msg) {
die('<b>PDF-Parser Error:</b> '.$msg); }
/**
* Check Trailer for Encryption
*/
function getEncryption() {
if (isset($this->xref['trailer'][1]['/Encrypt'])) {
$this->error('File is encrypted!');
}
}
/**
* Find/Return /Root
*
* @return array
*/
function pdf_find_root() {
if ($this->xref['trailer'][1]['/Root'][0] != PDF_TYPE_OBJREF) {
$this->error('Wrong Type of Root-Element! Must be an indirect reference');
}
return $this->xref['trailer'][1]['/Root'];
}
/**
* Read the /Root
*/
function pdf_read_root() {
// read root
$this->root = $this->pdf_resolve_object($this->c, $this->pdf_find_root());
}
/**
* Get PDF-Version
*
* And reset the PDF Version used in FPDI if needed
*/
function getPDFVersion() {
fseek($this->f, 0);
preg_match('/\d\.\d/',fread($this->f,16),$m);
if (isset($m[0]))
$this->pdfVersion = $m[0];
return $this->pdfVersion;
}
/**
* Find the xref-Table
*/
function pdf_find_xref() {
$toRead = 1500;
$stat = fseek ($this->f, -$toRead, SEEK_END);
if ($stat === -1) {
fseek ($this->f, 0);
}
$data = fread($this->f, $toRead);
$pos = strlen($data) - strpos(strrev($data), strrev('startxref'));
$data = substr($data, $pos);
if (!preg_match('/\s*(\d+).*$/s', $data, $matches)) {
$this->error('Unable to find pointer to xref table');
}
return (int) $matches[1];
}
/**
* Read xref-table
* * @param array $result Array of xref-table
* @param integer $offset of xref-table
*/
function pdf_read_xref(&$result, $offset) {
$o_pos = $offset-min(20, $offset);
fseek($this->f, $o_pos); // set some bytes backwards to fetch errorious docs
$data = fread($this->f, 100);
$xrefPos = strrpos($data, 'xref');
if ($xrefPos === false) {
fseek($this->f, $offset);
$c = new pdf_context($this->f);
$xrefStreamObjDec = $this->pdf_read_value($c);
if (is_array($xrefStreamObjDec) && isset($xrefStreamObjDec[0]) && $xrefStreamObjDec[0] == PDF_TYPE_OBJDEC) {
$this->error(sprintf('This document (%s) probably uses a compression technique which is not supported by the free parser shipped with FPDI.', $this->filename));
} else {
$this->error('Unable to find xref table.');
}
}
if (!isset($result['xref_location'])) {
$result['xref_location'] = $o_pos+$xrefPos;
$result['max_object'] = 0;
}
$cylces = -1;
$bytesPerCycle = 100;
fseek($this->f, $o_pos = $o_pos+$xrefPos+4); // set the handle directly after the "xref"-keyword
$data = fread($this->f, $bytesPerCycle);
while (($trailerPos = strpos($data, 'trailer', max($bytesPerCycle*$cylces++, 0))) === false && !feof($this->f)) {
$data .= fread($this->f, $bytesPerCycle);
}
if ($trailerPos === false) {
$this->error('Trailer keyword not found after xref table');
}
$data = substr($data, 0, $trailerPos);
// get Line-Ending
preg_match_all("/(\r\n|\n|\r)/", substr($data, 0, 100), $m); // check the first 100 bytes for linebreaks
$differentLineEndings = count(array_unique($m[0]));
if ($differentLineEndings > 1) {
$lines = preg_split("/(\r\n|\n|\r)/", $data, -1, PREG_SPLIT_NO_EMPTY);
} else {
$lines = explode($m[0][1], $data);
}
$data = $differentLineEndings = $m = null;
unset($data, $differentLineEndings, $m);
$linesCount = count($lines);
$start = 1;
for ($i = 0; $i < $linesCount; $i++) {
$line = trim($lines[$i]);
if ($line) {
$pieces = explode(' ', $line);
$c = count($pieces);
switch($c) {
case 2:
$start = (int)$pieces[0];
$end = $start+(int)$pieces[1]; if ($end > $result['max_object'])
$result['max_object'] = $end;
break;
case 3:
if (!isset($result['xref'][$start]))
$result['xref'][$start] = array();
if (!array_key_exists($gen = (int) $pieces[1], $result['xref'][$start])) {
$result['xref'][$start][$gen] = $pieces[2] == 'n' ? (int) $pieces[0] : null;
}
$start++;
break;
default:
$this->error('Unexpected data in xref table');
}
}
}
$lines = $pieces = $line = $start = $end = $gen = null;
unset($lines, $pieces, $line, $start, $end, $gen);
fseek($this->f, $o_pos+$trailerPos+7);
$c = new pdf_context($this->f);
$trailer = $this->pdf_read_value($c);
$c = null;
unset($c);
if (!isset($result['trailer'])) {
$result['trailer'] = $trailer;
}
if (isset($trailer[1]['/Prev'])) {
$this->pdf_read_xref($result, $trailer[1]['/Prev'][1]);
}
$trailer = null;
unset($trailer);
return true;
}
/**
* Reads an Value
*
* @param object $c pdf_context
* @param string $token a Token
* @return mixed
*/
function pdf_read_value(&$c, $token = null) {
if (is_null($token)) {
$token = $this->pdf_read_token($c);
}
if ($token === false) {
return false;
}
switch ($token) {
case '<':
// This is a hex string.
// Read the value, then the terminator
$pos = $c->offset;
while(1) {
$match = strpos ($c->buffer, '>', $pos);
// If you can't find it, try
// reading more data from the stream
if ($match === false) {
if (!$c->increase_length()) {
return false;
} else {
continue;
}
}
$result = substr ($c->buffer, $c->offset, $match - $c->offset);
$c->offset = $match + 1;
return array (PDF_TYPE_HEX, $result);
}
break;
case '<<':
// This is a dictionary.
$result = array();
// Recurse into this function until we reach
// the end of the dictionary.
while (($key = $this->pdf_read_token($c)) !== '>>') {
if ($key === false) {
return false;
}
if (($value = $this->pdf_read_value($c)) === false) {
return false;
}
// Catch missing value
if ($value[0] == PDF_TYPE_TOKEN && $value[1] == '>>') {
$result[$key] = array(PDF_TYPE_NULL);
break;
}
$result[$key] = $value;
}
return array (PDF_TYPE_DICTIONARY, $result);
case '[':
// This is an array.
$result = array();
// Recurse into this function until we reach
// the end of the array.
while (($token = $this->pdf_read_token($c)) !== ']') {
if ($token === false) {
return false;
}
if (($value = $this->pdf_read_value($c, $token)) === false) {
return false;
}
$result[] = $value;
}
return array (PDF_TYPE_ARRAY, $result);
case '(' :
// This is a string
$pos = $c->offset;
$openBrackets = 1;
do {
for (; $openBrackets != 0 && $pos < $c->length; $pos++) {
switch (ord($c->buffer[$pos])) {
case 0x28: // '('
$openBrackets++;
break;
case 0x29: // ')'
$openBrackets--;
break;
case 0x5C: // backslash
$pos++;
}
}
} while($openBrackets != 0 && $c->increase_length());
$result = substr($c->buffer, $c->offset, $pos - $c->offset - 1);
$c->offset = $pos;
return array (PDF_TYPE_STRING, $result);
case 'stream':
$o_pos = ftell($c->file)-strlen($c->buffer);
$o_offset = $c->offset;
$c->reset($startpos = $o_pos + $o_offset);
$e = 0; // ensure line breaks in front of the stream
if ($c->buffer[0] == chr(10) || $c->buffer[0] == chr(13))
$e++;
if ($c->buffer[1] == chr(10) && $c->buffer[0] != chr(10))
$e++;
if ($this->actual_obj[1][1]['/Length'][0] == PDF_TYPE_OBJREF) {
$tmp_c = new pdf_context($this->f);
$tmp_length = $this->pdf_resolve_object($tmp_c, $this->actual_obj[1][1]['/Length']);
$length = $tmp_length[1][1];
} else {
$length = $this->actual_obj[1][1]['/Length'][1];
}
if ($length > 0) {
$c->reset($startpos+$e,$length);
$v = $c->buffer;
} else {
$v = '';
}
$c->reset($startpos+$e+$length+9); // 9 = strlen("endstream")
return array(PDF_TYPE_STREAM, $v);
default :
if (is_numeric ($token)) {
// A numeric token. Make sure that
// it is not part of something else.
if (($tok2 = $this->pdf_read_token ($c)) !== false) {
if (is_numeric ($tok2)) {
// Two numeric tokens in a row.
// In this case, we're probably in
// front of either an object reference
// or an object specification.
// Determine the case and return the data
if (($tok3 = $this->pdf_read_token ($c)) !== false) {
switch ($tok3) {
case 'obj' :
return array (PDF_TYPE_OBJDEC, (int) $token, (int) $tok2);
case 'R' :
return array (PDF_TYPE_OBJREF, (int) $token, (int) $tok2);
} // If we get to this point, that numeric value up
// there was just a numeric value. Push the extra
// tokens back into the stack and return the value.
array_push ($c->stack, $tok3);
}
}
array_push ($c->stack, $tok2);
}
if ($token === (string)((int)$token))
return array (PDF_TYPE_NUMERIC, (int)$token);
else
return array (PDF_TYPE_REAL, (float)$token);
} else if ($token == 'true' || $token == 'false') {
return array (PDF_TYPE_BOOLEAN, $token == 'true');
} else if ($token == 'null') {
return array (PDF_TYPE_NULL);
} else {
// Just a token. Return it.
return array (PDF_TYPE_TOKEN, $token);
}
}
}
/**
* Resolve an object
*
* @param object $c pdf_context
* @param array $obj_spec The object-data
* @param boolean $encapsulate Must set to true, cause the parsing and fpdi use this method only without this para
*/
function pdf_resolve_object(&$c, $obj_spec, $encapsulate = true) {
// Exit if we get invalid data
if (!is_array($obj_spec)) {
$ret = false;
return $ret;
}
if ($obj_spec[0] == PDF_TYPE_OBJREF) {
// This is a reference, resolve it
if (isset($this->xref['xref'][$obj_spec[1]][$obj_spec[2]])) {
// Save current file position
// This is needed if you want to resolve
// references while you're reading another object
// (e.g.: if you need to determine the length
// of a stream)
$old_pos = ftell($c->file);
// Reposition the file pointer and
// load the object header.
$c->reset($this->xref['xref'][$obj_spec[1]][$obj_spec[2]]);
$header = $this->pdf_read_value($c);
if ($header[0] != PDF_TYPE_OBJDEC || $header[1] != $obj_spec[1] || $header[2] != $obj_spec[2]) {
$toSearchFor = $obj_spec[1].' '.$obj_spec[2].' obj';
if (preg_match('/'.$toSearchFor.'/', $c->buffer)) {
$c->offset = strpos($c->buffer, $toSearchFor) + strlen($toSearchFor);
// reset stack
$c->stack = array();
} else {
$this->error("Unable to find object ({$obj_spec[1]}, {$obj_spec[2]}) at expected location");
}
}
// If we're being asked to store all the information
// about the object, we add the object ID and generation
// number for later use
$result = array();
$this->actual_obj =& $result;
if ($encapsulate) {
$result = array (
PDF_TYPE_OBJECT,
'obj' => $obj_spec[1],
'gen' => $obj_spec[2]
);
}
// Now simply read the object data until
// we encounter an end-of-object marker
while(1) {
$value = $this->pdf_read_value($c);
if ($value === false || count($result) > 4) {
// in this case the parser coudn't find an endobj so we break here
break;
}
if ($value[0] == PDF_TYPE_TOKEN && $value[1] === 'endobj') {
break;
}
$result[] = $value;
}
$c->reset($old_pos);
if (isset($result[2][0]) && $result[2][0] == PDF_TYPE_STREAM) {
$result[0] = PDF_TYPE_STREAM;
}
return $result;
}
} else {
return $obj_spec;
}
}
/**
* Reads a token from the file
*
* @param object $c pdf_context
* @return mixed
*/
function pdf_read_token(&$c)
{
// If there is a token available
// on the stack, pop it out and
// return it.
if (count($c->stack)) {
return array_pop($c->stack);
}
// Strip away any whitespace
do {
if (!$c->ensure_content()) {
return false;
}
$c->offset += strspn($c->buffer, " \n\r\t", $c->offset);
} while ($c->offset >= $c->length - 1);
// Get the first character in the stream
$char = $c->buffer[$c->offset++];
switch ($char) {
case '[':
case ']':
case '(':
case ')':
// This is either an array or literal string
// delimiter, Return it
return $char;
case '<':
case '>':
// This could either be a hex string or
// dictionary delimiter. Determine the
// appropriate case and return the token
if ($c->buffer[$c->offset] == $char) {
if (!$c->ensure_content()) {
return false;
}
$c->offset++;
return $char . $char;
} else {
return $char;
}
case '%':
// This is a comment - jump over it!
$pos = $c->offset;
while(1) {
$match = preg_match("/(\r\n|\r|\n)/", $c->buffer, $m, PREG_OFFSET_CAPTURE, $pos);
if ($match === 0) {
if (!$c->increase_length()) {
return false;
} else {
continue;
}
}
$c->offset = $m[0][1]+strlen($m[0][0]);
return $this->pdf_read_token($c);
}
default:
// This is "another" type of token (probably
// a dictionary entry or a numeric value)
// Find the end and return it.
if (!$c->ensure_content()) {
return false;
}
while(1) {
// Determine the length of the token
$pos = strcspn($c->buffer, " %[]<>()\r\n\t/", $c->offset);
if ($c->offset + $pos <= $c->length - 1) {
break; } else {
// If the script reaches this point,
// the token may span beyond the end
// of the current buffer. Therefore,
// we increase the size of the buffer
// and try again--just to be safe.
$c->increase_length();
}
}
$result = substr($c->buffer, $c->offset - 1, $pos + 1);
$c->offset += $pos;
return $result;
}
}
}
}