gzipperClass.php

<?php

class gzipper
{

public function gzipFile($file,$destination_directory = '')
{
 try
 {

 $this->validateFile($file);

 if(empty($destination_directory)) $destination_directory = $this->setDestinationDirectory($file);
 $this->validateDestination($destination_directory);

 $fileinfo = pathinfo($file);

 $filegz = $this->normalizeDirectoryPath($destination_directory) . $fileinfo['basename'] . '.gz';

 file_put_contents($filegz, gzencode(file_get_contents($file),9));
 chmod($filegz, fileperms($file));

 $this->validateCompressedOutput($filegz);

 }
 catch(Exception $e)
 {
  gzipperException::returnError($e);
 }

 return $filegz;
}

public function gunzipFile($file,$destination_directory = '')
{
 try
 {

 $this->validateFile($file);
 $this->validateAsDecompressableFile($file);

 if(empty($destination_directory)) $destination_directory = $this->setDestinationDirectory($file);
 $this->validateDestination($destination_directory);

 $fileinfo = pathinfo($file);

 $fileuz = $this->normalizeDirectoryPath($destination_directory) . $fileinfo['filename'];

 file_put_contents($fileuz, $this->gzdecode(file_get_contents($file),9));
 chmod($fileuz, fileperms($file));

 $this->validateDecompressedOutput($fileuz);

 }
 catch(Exception $e)
 {
  gzipperException::returnError($e);
 }

 return $fileuz;
}

public function gzipStringToFile($destination_directory,$file_name,$string)
{
 try
 {

  if(empty($string)) throw new gzipperException(gzipperError::STRINGEMPTY);
  if(empty($destination_directory)) throw new gzipperException(gzipperError::DIRECTORYNOTSET);

  $this->validateDestination($destination_directory);

  $filegz = $this->normalizeDirectoryPath($destination_directory) . $file_name . '.gz';

  echo $string;
  file_put_contents($filegz, gzencode($string,9));
  chmod($filegz, 0664);

  $this->validateCompressedOutput($filegz);

 } catch (Exception $e)
 {
   gzipperException::returnError($e);
 }

}

private function setDestinationDirectory($file)
{
  $fileinfo = pathinfo($file);

  return $fileinfo['dirname'];
}

private function normalizeDirectoryPath($directory)
{

 $lastcharacter = strrev($directory);
 $lastcharacter = $lastcharacter{0};

 if($lastcharacter !== DIRECTORY_SEPARATOR)
 {
  return $directory . DIRECTORY_SEPARATOR;
 }
 else
 {
  return $directory;
 }

}

private function validateAsDecompressableFile($file)
{

  $finfo = finfo_open(FILEINFO_MIME_TYPE);

  if(finfo_file($finfo, $file) !== "application/x-gzip") throw new gzipperException(gzipperError::NOTGZIPFILE);

  $fileinfo = pathinfo($file);

  if($fileinfo['extension'] !== 'gz') throw new gzipperException(gzipperError::NOGZEXTENSION);

}

private static function validateFile($file)
{
 if(empty($file)) throw new gzipperException(gzipperError::FILENOTSET);
 if(!file_exists($file)) throw new gzipperException(gzipperError::FILENOTFOUND);
 if(!is_writable($file)) throw new gzipperException(gzipperError::FILENOTREADABLE);
}

private static function validateDestination($destination_directory)
{

 if(empty($destination_directory)) throw new gzipperException(gzipperError::DIRECTORYNOTSET);

 if(!file_exists($destination_directory))
 {
  if(!mkdir($destination_directory,0755,true)) throw new gzipperException(gzipperError::DIRECTORYNOTCREATABLE);
 }
 else
 {
  if(!is_writable($destination_directory)) throw new gzipperException(gzipperError::DIRECTORYNOTWRITABLE);
 }
}

private static function validateCompressedOutput($destination_file)
{

 if(!file_exists($destination_file)) throw new gzipperException(gzipperError::GZIPFAILED);

}

private function validateDecompressedOutput($destination_file)
{

 echo $destination_file;

 if(!file_exists($destination_file)) throw new gzipperException(gzipperError::GUNZIPFAILED);

}

private function gzdecode($data) {
  $len = strlen($data);
  if ($len < 18 || strcmp(substr($data,0,2),"\x1f\x8b")) {
    return null;  // Not GZIP format (See RFC 1952)
  }
  $method = ord(substr($data,2,1));  // Compression method
  $flags  = ord(substr($data,3,1));  // Flags
  if ($flags & 31 != $flags) {
    // Reserved bits are set -- NOT ALLOWED by RFC 1952
    return null;
  }
  // NOTE: $mtime may be negative (PHP integer limitations)
  $mtime = unpack("V", substr($data,4,4));
  $mtime = $mtime[1];
  $xfl   = substr($data,8,1);
  $os    = substr($data,8,1);
  $headerlen = 10;
  $extralen  = 0;
  $extra     = "";
  if ($flags & 4) {
    // 2-byte length prefixed EXTRA data in header
    if ($len - $headerlen - 2 < 8) {
      return false;    // Invalid format
    }
    $extralen = unpack("v",substr($data,8,2));
    $extralen = $extralen[1];
    if ($len - $headerlen - 2 - $extralen < 8) {
      return false;    // Invalid format
    }
    $extra = substr($data,10,$extralen);
    $headerlen += 2 + $extralen;
  }

  $filenamelen = 0;
  $filename = "";
  if ($flags & 8) {
    // C-style string file NAME data in header
    if ($len - $headerlen - 1 < 8) {
      return false;    // Invalid format
    }
    $filenamelen = strpos(substr($data,8+$extralen),chr(0));
    if ($filenamelen === false || $len - $headerlen - $filenamelen - 1 < 8) {
      return false;    // Invalid format
    }
    $filename = substr($data,$headerlen,$filenamelen);
    $headerlen += $filenamelen + 1;
  }

  $commentlen = 0;
  $comment = "";
  if ($flags & 16) {
    // C-style string COMMENT data in header
    if ($len - $headerlen - 1 < 8) {
      return false;    // Invalid format
    }
    $commentlen = strpos(substr($data,8+$extralen+$filenamelen),chr(0));
    if ($commentlen === false || $len - $headerlen - $commentlen - 1 < 8) {
      return false;    // Invalid header format
    }
    $comment = substr($data,$headerlen,$commentlen);
    $headerlen += $commentlen + 1;
  }

  $headercrc = "";
  if ($flags & 1) {
    // 2-bytes (lowest order) of CRC32 on header present
    if ($len - $headerlen - 2 < 8) {
      return false;    // Invalid format
    }
    $calccrc = crc32(substr($data,0,$headerlen)) & 0xffff;
    $headercrc = unpack("v", substr($data,$headerlen,2));
    $headercrc = $headercrc[1];
    if ($headercrc != $calccrc) {
      return false;    // Bad header CRC
    }
    $headerlen += 2;
  }

  // GZIP FOOTER - These be negative due to PHP's limitations
  $datacrc = unpack("V",substr($data,-8,4));
  $datacrc = $datacrc[1];
  $isize = unpack("V",substr($data,-4));
  $isize = $isize[1];

  // Perform the decompression:
  $bodylen = $len-$headerlen-8;
  if ($bodylen < 1) {
    // This should never happen - IMPLEMENTATION BUG!
    return null;
  }
  $body = substr($data,$headerlen,$bodylen);
  $data = "";
  if ($bodylen > 0) {
    switch ($method) {
      case 8:
        // Currently the only supported compression method:
        $data = gzinflate($body);
        break;
      default:
        // Unknown compression method
        return false;
    }
  } else {
    // I'm not sure if zero-byte body content is allowed.
    // Allow it for now...  Do nothing...
  }

  // Verifiy decompressed size and CRC32:
  // NOTE: This may fail with large data sizes depending on how
  //       PHP's integer limitations affect strlen() since $isize
  //       may be negative for large sizes.
  if ($isize != strlen($data) || crc32($data) != $datacrc) {
    // Bad format!  Length or CRC doesn't match!
    return false;
  }
  return $data;
}

}

class gzipperError
{
 const FILENOTSET = 1401;
 const FILENOTFOUND = 1404;
 const FILENOTREADABLE = 1403;
 const DIRECTORYNOTSET = 2401;
 const DIRECTORYNOTCREATABLE = 2404;
 const DIRECTORYNOTWRITABLE = 2403;
 CONST GZIPFAILED = 9001;
 CONST GUNZIPFAILED = 9002;
 CONST NOTGZIPFILE = 9003;
 CONST NOTGZIPEXTENSION = 9004;
 CONST STRINGEMPTY = 3000;


 public static function getErrorMessage($error_code)
 {

   switch ($error_code) {

    case self::FILENOTSET:
     return "No file was specified";
     break;

    case self::DIRECTORYNOTSET:
     return "No directory was specified";
     break;

    case self::FILENOTFOUND:
     return  "The file cannot be found";
     break;

    case self::FILENOTREADABLE:
     return  "The file cannot be opened";
     break;

    case self::DIRECTORYNOTCREATABLE:
     return "The destination directory does not exist and could not be created";
     break;

    case self::DIRECTORYNOTWRITABLE:
     return "The destination directory exists, but is not writable";
     break;

    case self::GZIPFAILED:
     return "Expected to find a gzipped file--however, none exists.";
     break;

    case self::GUNZIPFAILED:
     return "Expected to find an unzipped file--however, none exists.";
     break;

    case self::NOTGZIPFILE:
     return "The file specified for decompression is not of the correct MIME/Content-Type (application/x-gzip)";
     break;

    case self::NOTGZIPEXTENSION:
     return "The file specified for decompression does not have the correct .gz extension";
     break;

    case self::STRINGEMPTY:
     return "The string specified for compression is empty. Seriously, don't compress that";
     break;

    default:
     return "Unknown error occured";
     break;
   }

 }
}

class gzipperException extends Exception
{

    public function __construct($code = 0, Exception $previous = null) {

        parent::__construct(gzipperError::getErrorMessage($code), $code, $previous);
    }

    public function __toString() {
        return __CLASS__ . ": [{$this->code}]: {$this->message}\n";
    }

    public static function returnError($e)
    {
       echo "<pre>";
       echo $e->__toString() . "<br>";
       echo $e->getTraceAsString() . "<br>";
       echo "</pre>";
    }
}