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Diffstat (limited to 'includes/getid3/module.misc.pdf.php')
| -rw-r--r-- | includes/getid3/module.misc.pdf.php | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/includes/getid3/module.misc.pdf.php b/includes/getid3/module.misc.pdf.php new file mode 100644 index 0000000..1aca6ae --- /dev/null +++ b/includes/getid3/module.misc.pdf.php @@ -0,0 +1,147 @@ +<?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 +{ + public $returnXREF = false; // return full details of PDF Cross-Reference Table (XREF) + + /** + * @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; + } + } + } + } + foreach ($info['pdf']['xref']['offset'] as $objectNumber => $offset) { + if ($info['pdf']['xref']['entry'][$objectNumber] == 'f') { + // "free" object means "deleted", ignore + continue; + } + $this->fseek($offset); + $line = rtrim($this->fgets()); + if (preg_match('#^'.$objectNumber.' ([0-9]+) obj#', $line, $matches)) { + if (strlen($line) > strlen($matches[0])) { + // object header line not actually on its own line, rewind file pointer to start reading data + $this->fseek($offset + strlen($matches[0])); + } + $objectData = ''; + while (true) { + $line = $this->fgets(); + if (rtrim($line) == 'endobj') { + break; + } + $objectData .= $line; + } + 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 { + $this->error('Unexpected structure "'.$line.'" at offset '.$offset); + break; + } + } + if (!$this->returnXREF) { + unset($info['pdf']['xref']['offset'], $info['pdf']['xref']['generation'], $info['pdf']['xref']['entry']); + } + + } 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())); + $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; + } + +} |