vendor/getid3/module.graphic.png.php

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<?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.graphic.png.php                                      //
// module for analyzing PNG Image files                        //
// dependencies: NONE                                          //
//                                                            ///
/////////////////////////////////////////////////////////////////

if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers
	exit;
}

class getid3_png extends getid3_handler
{
	/**
	 * If data chunk is larger than this do not read it completely (getID3 only needs the first
	 * few dozen bytes for parsing).
	 *
	 * @var int
	 */
	public $max_data_bytes = 10000000;

	/**
	 * @return bool
	 */
	public function Analyze() {

		$info = &$this->getid3->info;

		// shortcut
		$info['png'] = array();
		$thisfile_png = &$info['png'];

		$info['fileformat']          = 'png';
		$info['video']['dataformat'] = 'png';
		$info['video']['lossless']   = false;

		$this->fseek($info['avdataoffset']);
		$PNGfiledata = $this->fread($this->getid3->fread_buffer_size());
		$offset = 0;

		$PNGidentifier = substr($PNGfiledata, $offset, 8); // $89 $50 $4E $47 $0D $0A $1A $0A
		$offset += 8;

		if ($PNGidentifier != "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A") {
			$this->error('First 8 bytes of file ('.getid3_lib::PrintHexBytes($PNGidentifier).') did not match expected PNG identifier');
			unset($info['fileformat']);
			return false;
		}

		while ((($this->ftell() - (strlen($PNGfiledata) - $offset)) < $info['filesize'])) {
			$chunk['data_length'] = getid3_lib::BigEndian2Int(substr($PNGfiledata, $offset, 4));