gzdecode

To decode / uncompress the received HTTP POST data in PHP code, request data coming from Java / Android application via HTTP POST GZIP / DEFLATE compressed format1) Data sent from Java Android app to PHP using DeflaterOutputStream java class and received in PHP as shown belowecho gzinflate( substr($HTTP_RAW_POST_DATA,2,-4) ) . PHP_EOL  . PHP_EOL;2) Data sent from Java Android app to PHP using GZIPOutputStream java class and received in PHP code as shown belowecho gzinflate( substr($HTTP_RAW_POST_DATA,10,-8) ) . PHP_EOL  . PHP_EOL;From Java Android side (API level 10+), data being sent in DEFLATE compressed format        String body = "Lorem ipsum shizzle ma nizle";        URL url = new URL("http://www.url.com/postthisdata.php");        URLConnection conn = url.openConnection();        conn.setDoOutput(true);        conn.setRequestProperty("Content-encoding", "deflate");        conn.setRequestProperty("Content-type", "application/octet-stream");        DeflaterOutputStream dos = new DeflaterOutputStream(                conn.getOutputStream());        dos.write(body.getBytes());        dos.flush();        dos.close();        BufferedReader in = new BufferedReader(new InputStreamReader(                conn.getInputStream()));        String decodedString = "";        while ((decodedString = in.readLine()) != null) {            Log.e("dump",decodedString);        }        in.close();On PHP side (v 5.3.1), code for decompressing this DEFLATE data will be    echo substr($HTTP_RAW_POST_DATA,2,-4);From Java Android side (API level 10+), data being sent in GZIP compressed format        String body1 = "Lorem ipsum shizzle ma nizle";        URL url1 = new URL("http://www.url.com/postthisdata.php");        URLConnection conn1 = url1.openConnection();        conn1.setDoOutput(true);        conn1.setRequestProperty("Content-encoding", "gzip");        conn1.setRequestProperty("Content-type", "application/octet-stream");        GZIPOutputStream dos1 = new GZIPOutputStream(conn1.getOutputStream());        dos1.write(body1.getBytes());        dos1.flush();        dos1.close();        BufferedReader in1 = new BufferedReader(new InputStreamReader(                conn1.getInputStream()));        String decodedString1 = "";        while ((decodedString1 = in1.readLine()) != null) {            Log.e("dump",decodedString1);        }        in1.close();On PHP side (v 5.3.1), code for decompressing this GZIP data will be    echo substr($HTTP_RAW_POST_DATA,10,-8);Useful PHP code for printing out compressed data using all available formats.$data = "Lorem ipsum shizzle ma nizle";echo "\n\n\n";for($i=-1;$i<=9;$i++)    echo chunk_split(strtoupper(bin2hex(gzcompress($data,$i))),2," ") . PHP_EOL  . PHP_EOL;echo "\n\n\n";for($i=-1;$i<=9;$i++)    echo chunk_split(strtoupper(bin2hex(gzdeflate($data,$i))),2," ") . PHP_EOL  . PHP_EOL;echo "\n\n\n";for($i=-1;$i<=9;$i++)    echo chunk_split(strtoupper(bin2hex(gzencode($data,$i,FORCE_GZIP))),2," ") . PHP_EOL  . PHP_EOL;echo "\n\n\n";for($i=-1;$i<=9;$i++)    echo chunk_split(strtoupper(bin2hex(gzencode($data,$i,FORCE_DEFLATE))),2," ") . PHP_EOL  . PHP_EOL;echo "\n\n\n";Hope this helps. Please ThumbsUp if this saved you a lot of effort and time.

I don't have any deep knowledge in compression algorithms and formats, so I have no idea if this works the same on all platforms. But by several experiments on my Linux box I found how to get gzdecoded data without temporary files. Here it is:

<?php
function gzdecode($data)
{
   return gzinflate(substr($data,10,-8));
}
?>

That's it. Simply strip header and footer bytes and you get raw deflated data for inflation.

3 more bugs found and fixed: 1. failed to work when the gz contained a filename - FIXED2. failed to work on 64-bit architecture (checksum) - FIXED3. failed to work when the gz contained a comment - cannot verify. Returns some errors (not all!) and filename.<?php function gzdecode($data,&$filename='',&$error='',$maxlength=null) {    $len = strlen($data);    if ($len < 18 || strcmp(substr($data,0,2),"\x1f\x8b")) {        $error = "Not in GZIP format.";        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) {        $error = "Reserved bits not allowed.";        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        }        $extralen = unpack("v",substr($data,8,2));        $extralen = $extralen[1];        if ($len - $headerlen - 2 - $extralen < 8) {            return false;  // invalid        }        $extra = substr($data,10,$extralen);        $headerlen += 2 + $extralen;    }    $filenamelen = 0;    $filename = "";    if ($flags & 8) {        // C-style string        if ($len - $headerlen - 1 < 8) {            return false; // invalid        }        $filenamelen = strpos(substr($data,$headerlen),chr(0));        if ($filenamelen === false || $len - $headerlen - $filenamelen - 1 < 8) {            return false; // invalid        }        $filename = substr($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        }        $commentlen = strpos(substr($data,$headerlen),chr(0));        if ($commentlen === false || $len - $headerlen - $commentlen - 1 < 8) {            return false;    // Invalid header format        }        $comment = substr($data,$headerlen,$commentlen);        $headerlen += $commentlen + 1;    }    $headercrc = "";    if ($flags & 2) {        // 2-bytes (lowest order) of CRC32 on header present        if ($len - $headerlen - 2 < 8) {            return false;    // invalid        }        $calccrc = crc32(substr($data,0,$headerlen)) & 0xffff;        $headercrc = unpack("v", substr($data,$headerlen,2));        $headercrc = $headercrc[1];        if ($headercrc != $calccrc) {            $error = "Header checksum failed.";            return false;    // Bad header CRC        }        $headerlen += 2;    }    // GZIP FOOTER    $datacrc = unpack("V",substr($data,-8,4));    $datacrc = sprintf('%u',$datacrc[1] & 0xFFFFFFFF);    $isize = unpack("V",substr($data,-4));    $isize = $isize[1];    // decompression:    $bodylen = $len-$headerlen-8;    if ($bodylen < 1) {        // 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,$maxlength);            break;        default:            $error = "Unknown compression method.";            return false;        }    }  // zero-byte body content is allowed    // Verifiy CRC32    $crc   = sprintf("%u",crc32($data));    $crcOK = $crc == $datacrc;    $lenOK = $isize == strlen($data);    if (!$lenOK || !$crcOK) {        $error = ( $lenOK ? '' : 'Length check FAILED. ') . ( $crcOK ? '' : 'Checksum FAILED.');        return false;    }    return $data;}?>

Aaron G. 07-Aug-2004 03:29 posted the function gzdecode()to gzencode comments. I FIXED the BUG: if($flags & 1) to the correct if($flags & 2)Unfortunately the function gzencode() does NOT append a CRC so I did not notice until I tried to upload a file compressed with gzip itself.<?phpfunction 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 & 2) {    // 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;}?>

I have used this simple function to gzdecode gzipped files downloaded from the web.<?phpfunction gzdecode($data){  $g=tempnam('/tmp','ff');  @file_put_contents($g,$data);  ob_start();  readgzfile($g);  $d=ob_get_clean();  return $d;}?>

This can help to decompress the data from tar archive in certain cases, hope this helps somebody<?php$tarName = 'example.ini';try {    /** For files with tar.gz extensions **/    $phar = new \PharData($path, 0, $tarName);} catch ($e) {    /** Decode the file first **/    $decodedFile = file_put_contents($path, gzdecode(file_get_contents($path)));    /** create PharData object second **/    $phar = new \PharData($path, 0, $tarName);}?>