PHP 5.5.15 is released

gzdecode

(PHP 5 >= 5.4.0)

gzdecodeDecodifica uma string comprimida usando o gzip

Descrição

string gzdecode ( string $data [, int $length ] )

Essa função retorna a versão decodifica de data.

Parâmetros

data

Os dados a serem decodificados, encodificados por gzencode().

length

Tamanho máximo dos dados a serem decodificados.

Valor Retornado

A string decodificada, ou FALSE se um erro ocorrer.

Veja Também

  • gzencode() - Cria uma string comprimida com gzip

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User Contributed Notes 8 notes

up
7
anonymous at dekho-ji dot com
1 year ago
To decode / uncompress the received HTTP POST data in PHP code, request data coming from Java / Android application via HTTP POST GZIP / DEFLATE compressed format

1) Data sent from Java Android app to PHP using DeflaterOutputStream java class and received in PHP as shown below
echo 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 below
echo 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.
up
6
tomas at slax dot org
2 years ago
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.
up
3
webmaster at askapache dot com
6 years ago
I have used this simple function to gzdecode gzipped files downloaded from the web.

<?php

function gzdecode($data){
 
$g=tempnam('/tmp','ff');
  @
file_put_contents($g,$data);
 
ob_start();
 
readgzfile($g);
 
$d=ob_get_clean();
  return
$d;
}

?>
up
2
katzlbtjunk at hotmail dot com
6 years ago
3 more bugs found and fixed:
1. failed to work when the gz contained a filename - FIXED
2. failed to work on 64-bit architecture (checksum) - FIXED
3. 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
$data;
}
?>
up
2
katzlbtjunk at hotmail dot com
6 years ago
Aaron G. 07-Aug-2004 03:29 posted the function gzdecode()
to gzencode comments. I FIXED the BUG: if($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.

<?php

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 & 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;
}

?>
up
0
Anonymous
6 days ago
if (!function_exists('gzdecode')) {
    function gzdecode($data)
    {
        return gzinflate(substr($data,10,-8));
    }
}
up
-4
6869hlopcik at inbox dot lv
2 years ago
Windows compitable with auto delete temp file.

<?php
function softcoded_gzdecode($data){
   
$g=tempnam('./','gz');
   
file_put_contents($g,$data);
   
ob_start();
   
readgzfile($g);
   
$d=ob_get_clean();
   
unlink($g);
    return
$d;
}
?>
up
-4
TheSeoDude
6 years ago
This function is not found in any of the PHP distribution I use and used so had to figure out a replacement in order to extract and process my server's raw logs automagically.

Check it here http://www.tellinya.com/art2/83/gzdecode . Just a function to extract gzencoded data and hope it helps any1.
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