name : module.misc.pdf.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; } }