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Класс для создания архивов GZip

/**********************************************************************************
gzip - PHP gzip compression library
        Version 1.3

Copyright (c) 2001, 2002 Moiseenko V. Maxim <m.moiseenko@sys4tec.com>
All Rights Reserved.

This library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2.1 of the License, or any
later version.

This library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.

**********************************************************************************/

define("_GZIP",true);
define("_GZIP_VER", 1.3);
define("_GZIP_BUILD", '03.04.2002');


###################################################################################
class gzip {

 # Array to store compressed data
 # private string[]
 var $_datasec = [];

 # îòîáðàæàòü îòëàäî÷íîå èíôî.
 # public boolean
 var $debug = true;

 /******************************************************************************
 * êîíñòðóêòîð êëàññà
 * public void
 */
 function gzip(){  }

 /******************************************************************************
 * Adds "file content" to archive
 *
 * public void
 * string @data - file contents
 * string @name - name of the file in the archive (may contains the path)
 */
 function add($data, $name){
  $unc_len = strlen($data);
  $crc   = crc32($data);
  $zdata = gzdeflate($data,9);
  $c_len = strlen($zdata);

  $fr=
   "\x1f".          # ID1               1
   "\x8B".          # ID2               1
   "\x08".          # Compression Method "deflate"   1
   "\x08".          # FLaGs "FNAME"          1
   "\x00\x00\x00\x00".    # last mod time & date       4
   "\x00".          # eXtra FLags "2"-max "4"-fast   1
   "\x00".          # OS "\x00" - FAT         1
   $name.           # orig. file name        var
   "\x00".          # zero term.            1
   $zdata.
   $this->_pack($crc, 4).   # crc32              4
   $this->_pack($unc_len, 4); # uncompressed filesize      4

  $this->_datasec[] = $fr;
 }


 /********************************************************************************
 * ðàñïàêîâàâàåò ñîäåðæèìîå àðõèâà
 * public object
 */
 function extract($name){
  if(!file_exists($name))return null;
  $fd = fopen($name,'rb');
  if(! $content = fread($fd, filesize($name)) ) return null;
  @fclose($fd);

  $ret = new stdClass;

  # ìàññèâ äëÿ ðàñïàêîâàíîãî ñîäåðæèìîãî
  $ret->part = [];
  # óêàçàòåëü ïîçèöèè ÷òåíèÿ
  $pointer=0;
  # íîìåð ôàéëà
  $fpointer = 0;
  $ret->part[$fpointer]->head = [];

  if("\x1f\x8b" != substr($content, $pointer,2) ){
   $this->_debug("It's not .gzip format");
   return null;
  }
  $pointer+=2;

  if("\x08" != substr($content, $pointer,1) ){
   $this->_debug("Compression method must be 'deflate'");
   return null;
  }
  $pointer++;


  # This flag byte is divided into individual bits as follows:
  # bit 0  FTEXT
  # bit 1  FHCRC
  # bit 2  FEXTRA
  # bit 3  FNAME
  # bit 4  FCOMMENT
  switch( substr($content, $pointer,1) ){
   #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   # FNAME
   case "\x08":

    $pointer++;

    # Modification time
    $ret->part[$fpointer]->head['mod_time'] =
     $this->_unpack( substr($content, $pointer,2) );
    $pointer+=2;

    # Modification date
    $ret->part[$fpointer]->head['mod_date'] =
     $this->_unpack( substr($content, $pointer,2) );
    $pointer+=2;

    # eXtra FLags
    # 2 - compressor used maximum compression, slowest algorithm
    # 4 - compressor used fastest algorithm
    $ret->part[$fpointer]->head['xfl'] =
     $this->_unpack( substr($content, $pointer,1) );
    $pointer++;

    # Operating System
    # 0 - FAT filesystem (MS-DOS, OS/2, NT/Win32)
    # 3 - Unix
    # 7 - Macintosh
    # 11 - NTFS filesystem (NT)
    # 255 - unknown
    $ret->part[$fpointer]->head['os'] = $this->_unpack( substr($content, $pointer,1) );
    $pointer++;

    #file name
    for($ret->part[$fpointer]->head['file_name']=""; substr($content, $pointer,1) != "\x00"; $pointer++)
     $ret->part[$fpointer]->head['file_name'] .= substr($content, $pointer,1);
    $pointer++;

    # compressed blocks...
    $zdata = substr($content, $pointer, -8);
    $pointer = strlen($content) - 8;

    # Cyclic Redundancy Check
    $ret->part[$fpointer]->head['crc32'] =
     $this->_unpack( substr($content, $pointer,4) );
    $pointer+=4;

    # size of the original (uncompressed) input data modulo 2^32
    $ret->part[$fpointer]->head['uncompressed_filesize'] =
     $this->_unpack( substr($content, $pointer,4) );
    $pointer+=4;


    # decompress data and store it at array
    $ret->part[$fpointer]->body = gzinflate($zdata);

    break;


   #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   default:
    return null;

  }#switch

  return $ret;
 }


 /******************************************************************************
 * Dumps out file
 *
 * public string - the gzipped file
 */
 function file(){
  $data = implode('', $this->_datasec);
  return $data;
 }


 /******************************************************************************
 * print error message
 * public void
 */
 function _debug($str){
  if($this->debug) echo $str;
 }


 /********************************************************************************
 * pack data into binary string
 * private string
 */
 function _pack($val, $bytes=2){
  for($ret='', $i=0; $i<$bytes; $i++, $val=floor($val/256) )
   $ret .= chr($val % 256);
  return $ret;
 }


 /********************************************************************************
 * unpack data from binary string
 * private string
 */
 function _unpack($val){
  for($len = strlen($val), $ret=0, $i=0; $i < $len; $i++)
   $ret += (int)ord(substr($val,$i,1)) * pow(2, 8 * $i);
  return $ret;
 }


 /********************************************************************************
 * äîáàâëÿåò ñîäåðæèìîå ôàéëà â àðõèâ
 * public boolean
 */
 function add_file($name, $binary=false){
  if(!file_exists($name))return false;
  $fd = $binary? fopen($name,'rb') : fopen($name,'r');
  if(! $content = fread($fd, filesize($name)) )return false;
  fclose($fd);

  $this->add($content,$name);
  return true;
 }


 /********************************************************************************
 * ñîçäà¸ò .zip àðõèâ
 * public int
 */
 function write_file($name){
  $size = -1;
  if( $fd=fopen($name,'wb') ){
   $size = fwrite($fd,$this->file());
   fclose($fd);
  }
  return $size;
 }

}

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