119 lines
2.8 KiB
PHP
119 lines
2.8 KiB
PHP
<?php
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/**
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* Akeeba Engine
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*
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* @package akeebaengine
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* @copyright Copyright (c)2006-2022 Nicholas K. Dionysopoulos / Akeeba Ltd
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* @license GNU General Public License version 3, or later
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*/
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namespace Akeeba\Engine\Util;
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defined('AKEEBAENGINE') || die();
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use Akeeba\Engine\Factory;
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/**
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* A handy class to abstract the calculation of CRC32 of files under various
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* server conditions and versions of PHP.
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*/
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class CRC32
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{
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/**
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* Returns the CRC32 of a file, selecting the more appropriate algorithm.
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*
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* @param string $filename Absolute path to the file being processed
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* @param integer $AkeebaPackerZIP_CHUNK_SIZE Obsoleted
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*
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* @return integer The CRC32 in numerical form
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*/
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public function crc32_file($filename, $AkeebaPackerZIP_CHUNK_SIZE)
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{
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static $configuration;
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if (!$configuration)
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{
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$configuration = Factory::getConfiguration();
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}
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$res = false;
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if (function_exists("hash_file"))
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{
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$res = $this->crc32UsingHashExtension($filename);
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Factory::getLog()->debug("File $filename - CRC32 = " . dechex($res) . " [HASH_FILE]");
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}
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else if (function_exists("file_get_contents") && (@filesize($filename) <= $AkeebaPackerZIP_CHUNK_SIZE))
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{
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$res = $this->crc32Legacy($filename);
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Factory::getLog()->debug("File $filename - CRC32 = " . dechex($res) . " [FILE_GET_CONTENTS]");
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}
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else
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{
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$res = 0;
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Factory::getLog()->debug("File $filename - CRC32 = " . dechex($res) . " [FAKE - CANNOT CALCULATE]");
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}
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if ($res === false)
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{
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$res = 0;
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Factory::getLog()->warning("File $filename - NOT READABLE: CRC32 IS WRONG!");
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}
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return $res;
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}
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/**
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* Very efficient CRC32 calculation using the PHP 'hash' extension.
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*
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* @param string $filename Absolute filepath
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*
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* @return integer The CRC32
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*/
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protected function crc32UsingHashExtension($filename)
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{
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// Detection of buggy PHP hosts
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static $mustInvert = null;
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if (is_null($mustInvert))
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{
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$test_crc = @hash('crc32b', 'test', false);
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$mustInvert = (strtolower($test_crc) == '0c7e7fd8'); // Normally, it's D87F7E0C :)
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if ($mustInvert)
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{
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Factory::getLog()->warning('Your server has a buggy PHP version which produces inverted CRC32 values. Attempting a workaround. ZIP files may appear as corrupt.');
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}
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}
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$res = @hash_file('crc32b', $filename, false);
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if ($mustInvert)
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{
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// Workaround for buggy PHP versions (I think before 5.1.8) which produce inverted CRC32 sums
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$res2 = substr($res, 6, 2) . substr($res, 4, 2) . substr($res, 2, 2) . substr($res, 0, 2);
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$res = $res2;
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}
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$res = hexdec($res);
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return $res;
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}
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/**
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* A compatible CRC32 calculation using file_get_contents, utilizing immense amounts of RAM
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*
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* @param string $filename
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*
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* @return integer
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*/
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protected function crc32Legacy($filename)
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{
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return crc32(@file_get_contents($filename));
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}
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}
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