367 lines
8.3 KiB
PHP
367 lines
8.3 KiB
PHP
<?php
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/**
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* SimplePie
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*
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* A PHP-Based RSS and Atom Feed Framework.
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* Takes the hard work out of managing a complete RSS/Atom solution.
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*
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* Copyright (c) 2004-2016, Ryan Parman, Sam Sneddon, Ryan McCue, and contributors
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification, are
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* permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice, this list of
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* conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright notice, this list
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* of conditions and the following disclaimer in the documentation and/or other materials
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* provided with the distribution.
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*
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* * Neither the name of the SimplePie Team nor the names of its contributors may be used
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* to endorse or promote products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS
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* AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* @package SimplePie
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* @copyright 2004-2016 Ryan Parman, Sam Sneddon, Ryan McCue
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* @author Ryan Parman
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* @author Sam Sneddon
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* @author Ryan McCue
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* @link http://simplepie.org/ SimplePie
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* @license http://www.opensource.org/licenses/bsd-license.php BSD License
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*/
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/**
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* Decode 'gzip' encoded HTTP data
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*
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* @package SimplePie
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* @subpackage HTTP
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* @link http://www.gzip.org/format.txt
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*/
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class SimplePie_gzdecode
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{
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/**
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* Compressed data
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*
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* @access private
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* @var string
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* @see gzdecode::$data
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*/
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var $compressed_data;
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/**
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* Size of compressed data
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*
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* @access private
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* @var int
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*/
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var $compressed_size;
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/**
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* Minimum size of a valid gzip string
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*
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* @access private
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* @var int
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*/
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var $min_compressed_size = 18;
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/**
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* Current position of pointer
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*
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* @access private
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* @var int
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*/
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var $position = 0;
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/**
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* Flags (FLG)
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*
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* @access private
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* @var int
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*/
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var $flags;
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/**
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* Uncompressed data
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*
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* @access public
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* @see gzdecode::$compressed_data
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* @var string
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*/
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var $data;
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/**
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* Modified time
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*
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* @access public
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* @var int
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*/
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var $MTIME;
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/**
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* Extra Flags
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*
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* @access public
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* @var int
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*/
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var $XFL;
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/**
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* Operating System
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*
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* @access public
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* @var int
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*/
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var $OS;
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/**
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* Subfield ID 1
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*
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* @access public
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* @see gzdecode::$extra_field
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* @see gzdecode::$SI2
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* @var string
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*/
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var $SI1;
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/**
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* Subfield ID 2
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*
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* @access public
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* @see gzdecode::$extra_field
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* @see gzdecode::$SI1
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* @var string
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*/
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var $SI2;
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/**
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* Extra field content
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*
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* @access public
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* @see gzdecode::$SI1
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* @see gzdecode::$SI2
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* @var string
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*/
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var $extra_field;
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/**
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* Original filename
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*
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* @access public
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* @var string
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*/
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var $filename;
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/**
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* Human readable comment
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*
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* @access public
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* @var string
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*/
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var $comment;
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/**
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* Don't allow anything to be set
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*
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* @param string $name
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* @param mixed $value
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*/
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public function __set($name, $value)
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{
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trigger_error("Cannot write property $name", E_USER_ERROR);
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}
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/**
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* Set the compressed string and related properties
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*
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* @param string $data
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*/
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public function __construct($data)
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{
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$this->compressed_data = $data;
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$this->compressed_size = strlen($data);
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}
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/**
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* Decode the GZIP stream
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*
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* @return bool Successfulness
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*/
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public function parse()
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{
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if ($this->compressed_size >= $this->min_compressed_size)
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{
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// Check ID1, ID2, and CM
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if (substr($this->compressed_data, 0, 3) !== "\x1F\x8B\x08")
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{
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return false;
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}
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// Get the FLG (FLaGs)
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$this->flags = ord($this->compressed_data[3]);
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// FLG bits above (1 << 4) are reserved
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if ($this->flags > 0x1F)
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{
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return false;
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}
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// Advance the pointer after the above
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$this->position += 4;
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// MTIME
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$mtime = substr($this->compressed_data, $this->position, 4);
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// Reverse the string if we're on a big-endian arch because l is the only signed long and is machine endianness
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if (current(unpack('S', "\x00\x01")) === 1)
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{
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$mtime = strrev($mtime);
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}
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$this->MTIME = current(unpack('l', $mtime));
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$this->position += 4;
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// Get the XFL (eXtra FLags)
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$this->XFL = ord($this->compressed_data[$this->position++]);
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// Get the OS (Operating System)
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$this->OS = ord($this->compressed_data[$this->position++]);
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// Parse the FEXTRA
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if ($this->flags & 4)
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{
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// Read subfield IDs
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$this->SI1 = $this->compressed_data[$this->position++];
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$this->SI2 = $this->compressed_data[$this->position++];
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// SI2 set to zero is reserved for future use
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if ($this->SI2 === "\x00")
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{
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return false;
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}
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// Get the length of the extra field
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$len = current(unpack('v', substr($this->compressed_data, $this->position, 2)));
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$this->position += 2;
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// Check the length of the string is still valid
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$this->min_compressed_size += $len + 4;
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if ($this->compressed_size >= $this->min_compressed_size)
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{
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// Set the extra field to the given data
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$this->extra_field = substr($this->compressed_data, $this->position, $len);
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$this->position += $len;
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}
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else
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{
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return false;
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}
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}
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// Parse the FNAME
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if ($this->flags & 8)
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{
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// Get the length of the filename
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$len = strcspn($this->compressed_data, "\x00", $this->position);
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// Check the length of the string is still valid
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$this->min_compressed_size += $len + 1;
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if ($this->compressed_size >= $this->min_compressed_size)
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{
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// Set the original filename to the given string
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$this->filename = substr($this->compressed_data, $this->position, $len);
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$this->position += $len + 1;
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}
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else
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{
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return false;
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}
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}
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// Parse the FCOMMENT
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if ($this->flags & 16)
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{
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// Get the length of the comment
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$len = strcspn($this->compressed_data, "\x00", $this->position);
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// Check the length of the string is still valid
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$this->min_compressed_size += $len + 1;
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if ($this->compressed_size >= $this->min_compressed_size)
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{
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// Set the original comment to the given string
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$this->comment = substr($this->compressed_data, $this->position, $len);
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$this->position += $len + 1;
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}
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else
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{
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return false;
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}
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}
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// Parse the FHCRC
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if ($this->flags & 2)
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{
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// Check the length of the string is still valid
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$this->min_compressed_size += $len + 2;
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if ($this->compressed_size >= $this->min_compressed_size)
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{
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// Read the CRC
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$crc = current(unpack('v', substr($this->compressed_data, $this->position, 2)));
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// Check the CRC matches
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if ((crc32(substr($this->compressed_data, 0, $this->position)) & 0xFFFF) === $crc)
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{
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$this->position += 2;
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}
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else
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{
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return false;
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}
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}
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else
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{
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return false;
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}
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}
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// Decompress the actual data
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if (($this->data = gzinflate(substr($this->compressed_data, $this->position, -8))) === false)
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{
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return false;
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}
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$this->position = $this->compressed_size - 8;
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// Check CRC of data
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$crc = current(unpack('V', substr($this->compressed_data, $this->position, 4)));
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$this->position += 4;
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/*if (extension_loaded('hash') && sprintf('%u', current(unpack('V', hash('crc32b', $this->data)))) !== sprintf('%u', $crc))
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{
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return false;
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}*/
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// Check ISIZE of data
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$isize = current(unpack('V', substr($this->compressed_data, $this->position, 4)));
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$this->position += 4;
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if (sprintf('%u', strlen($this->data) & 0xFFFFFFFF) !== sprintf('%u', $isize))
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{
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return false;
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}
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// Wow, against all odds, we've actually got a valid gzip string
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return true;
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}
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return false;
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}
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}
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