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