159 lines
6.8 KiB
PHP
159 lines
6.8 KiB
PHP
<?php
|
|
|
|
/////////////////////////////////////////////////////////////////
|
|
/// getID3() by James Heinrich <info@getid3.org> //
|
|
// available at https://github.com/JamesHeinrich/getID3 //
|
|
// or https://www.getid3.org //
|
|
// or http://getid3.sourceforge.net //
|
|
// see readme.txt for more details //
|
|
/////////////////////////////////////////////////////////////////
|
|
// //
|
|
// module.misc.pdf.php //
|
|
// module for analyzing PDF files //
|
|
// dependencies: NONE //
|
|
// ///
|
|
/////////////////////////////////////////////////////////////////
|
|
|
|
if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers
|
|
exit;
|
|
}
|
|
|
|
class getid3_pdf extends getid3_handler
|
|
{
|
|
/** misc.pdf
|
|
* return full details of PDF Cross-Reference Table (XREF)
|
|
*
|
|
* @var bool
|
|
*/
|
|
public $returnXREF = false;
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
public function Analyze() {
|
|
$info = &$this->getid3->info;
|
|
$this->fseek(0);
|
|
if (preg_match('#^%PDF-([0-9\\.]+)$#', rtrim($this->fgets()), $matches)) {
|
|
$info['pdf']['header']['version'] = floatval($matches[1]);
|
|
$info['fileformat'] = 'pdf';
|
|
|
|
// the PDF Cross-Reference Table (XREF) is located near the end of the file
|
|
// the starting offset is specified in the penultimate section, on the two lines just before "%%EOF"
|
|
// the first line is "startxref", the second line is the byte offset of the XREF.
|
|
// We know the length of "%%EOF" and "startxref", but the offset could be 2-10 bytes,
|
|
// and we're not sure if the line ends are one or two bytes, so we might find "startxref" as little as 18(?) bytes
|
|
// from EOF, but it could 30 bytes, so we start 40 bytes back just to be safe and do a search for the data we want.
|
|
$this->fseek(-40, SEEK_END);
|
|
if (preg_match('#[\r\n]startxref[ \r\n]+([0-9]+)[ \r\n]+#', $this->fread(40), $matches)) {
|
|
$info['pdf']['trailer']['startxref'] = intval($matches[1]);
|
|
$this->parseXREF($info['pdf']['trailer']['startxref']);
|
|
if (!empty($info['pdf']['xref']['offset'])) {
|
|
while (!$this->feof() && (max(array_keys($info['pdf']['xref']['offset'])) > $info['pdf']['xref']['count'])) {
|
|
// suspect that there may be another XREF entry somewhere in the file, brute-force scan for it
|
|
/*
|
|
// starting at last known entry of main XREF table
|
|
$this->fseek(max($info['pdf']['xref']['offset']));
|
|
*/
|
|
// starting at the beginning of the file
|
|
$this->fseek(0);
|
|
while (!$this->feof()) {
|
|
$XREFoffset = $this->ftell();
|
|
if (rtrim($this->fgets()) == 'xref') {
|
|
if (empty($info['pdf']['xref']['xref_offsets']) || !in_array($XREFoffset, $info['pdf']['xref']['xref_offsets'])) {
|
|
$this->parseXREF($XREFoffset);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
asort($info['pdf']['xref']['offset']);
|
|
$maxObjLengths = array();
|
|
$prevOffset = 0;
|
|
$prevObjNum = 0;
|
|
foreach ($info['pdf']['xref']['offset'] as $objectNumber => $offset) {
|
|
// walk through all listed offsets to calculate the maximum possible length for each known object
|
|
if ($prevObjNum) {
|
|
$maxObjLengths[$prevObjNum] = $offset - $prevOffset;
|
|
}
|
|
$prevOffset = $offset;
|
|
$prevObjNum = $objectNumber;
|
|
}
|
|
ksort($maxObjLengths);
|
|
foreach ($info['pdf']['xref']['offset'] as $objectNumber => $offset) {
|
|
if ($info['pdf']['xref']['entry'][$objectNumber] == 'f') {
|
|
// "free" object means "deleted", ignore
|
|
continue;
|
|
}
|
|
if (!empty($maxObjLengths[$objectNumber]) && ($maxObjLengths[$objectNumber] < $this->getid3->option_fread_buffer_size)) {
|
|
// ignore object that are zero-size or >32kB, they are unlikely to contain information we're interested in
|
|
$this->fseek($offset);
|
|
$objBlob = $this->fread($maxObjLengths[$objectNumber]);
|
|
if (preg_match('#^'.$objectNumber.'[\\x00 \\r\\n\\t]*([0-9]+)[\\x00 \\r\\n\\t]*obj[\\x00 \\r\\n\\t]*(.*)(endobj)?[\\x00 \\r\\n\\t]*$#s', $objBlob, $matches)) {
|
|
list($dummy, $generation, $objectData) = $matches;
|
|
if (preg_match('#^<<[\r\n\s]*(/Type|/Pages|/Parent [0-9]+ [0-9]+ [A-Z]|/Count [0-9]+|/Kids *\\[[0-9A-Z ]+\\]|[\r\n\s])+[\r\n\s]*>>#', $objectData, $matches)) {
|
|
if (preg_match('#/Count ([0-9]+)#', $objectData, $matches)) {
|
|
$info['pdf']['pages'] = (int) $matches[1];
|
|
break; // for now this is the only data we're looking for in the PDF not need to loop through every object in the file (and a large PDF may contain MANY objects). And it MAY be possible that there are other objects elsewhere in the file that define additional (or removed?) pages
|
|
}
|
|
}
|
|
} else {
|
|
$this->error('Unexpected structure "'.substr($objBlob, 0, 100).'" at offset '.$offset);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
if (!$this->returnXREF) {
|
|
unset($info['pdf']['xref']['offset'], $info['pdf']['xref']['generation'], $info['pdf']['xref']['entry'], $info['pdf']['xref']['xref_offsets']);
|
|
}
|
|
|
|
} else {
|
|
$this->error('Did not find "xref" at offset '.$info['pdf']['trailer']['startxref']);
|
|
}
|
|
} else {
|
|
$this->error('Did not find "startxref" in the last 40 bytes of the PDF');
|
|
}
|
|
|
|
$this->warning('PDF parsing incomplete in this version of getID3() ['.$this->getid3->version().']');
|
|
return true;
|
|
}
|
|
$this->error('Did not find "%PDF" at the beginning of the PDF');
|
|
return false;
|
|
|
|
}
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
private function parseXREF($XREFoffset) {
|
|
$info = &$this->getid3->info;
|
|
|
|
$this->fseek($XREFoffset);
|
|
if (rtrim($this->fgets()) == 'xref') {
|
|
|
|
$info['pdf']['xref']['xref_offsets'][$XREFoffset] = $XREFoffset;
|
|
list($firstObjectNumber, $XREFcount) = explode(' ', rtrim($this->fgets()));
|
|
$firstObjectNumber = (int) $firstObjectNumber;
|
|
$XREFcount = (int) $XREFcount;
|
|
$info['pdf']['xref']['count'] = $XREFcount + (!empty($info['pdf']['xref']['count']) ? $info['pdf']['xref']['count'] : 0);
|
|
for ($i = 0; $i < $XREFcount; $i++) {
|
|
$line = rtrim($this->fgets());
|
|
if (preg_match('#^([0-9]+) ([0-9]+) ([nf])$#', $line, $matches)) {
|
|
$info['pdf']['xref']['offset'][($firstObjectNumber + $i)] = (int) $matches[1];
|
|
$info['pdf']['xref']['generation'][($firstObjectNumber + $i)] = (int) $matches[2];
|
|
$info['pdf']['xref']['entry'][($firstObjectNumber + $i)] = $matches[3];
|
|
} else {
|
|
$this->error('failed to parse XREF entry #'.$i.' in XREF table at offset '.$XREFoffset);
|
|
return false;
|
|
}
|
|
}
|
|
sort($info['pdf']['xref']['xref_offsets']);
|
|
return true;
|
|
|
|
}
|
|
$this->warning('failed to find expected XREF structure at offset '.$XREFoffset);
|
|
return false;
|
|
}
|
|
|
|
}
|