gzinflate

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

gzinflate — Inflate a deflated string

说明

gzinflate ( string $data , int $max_length = 0 ) : string|false

This function inflates a deflated string.

参数

data

The data compressed by gzdeflate().

max_length

The maximum length of data to decode.

返回值

The original uncompressed data or false on error.

The function will return an error if the uncompressed data is more than 32768 times the length of the compressed input data or more than the optional parameter max_length.

范例

Example #1 gzinflate() example

<?php
$compressed   = gzdeflate('Compress me', 9);
$uncompressed = gzinflate($compressed);
echo $uncompressed;
?>

参见

User Contributed Notes

anonymous at dekho-ji dot com 16-May-2013 11:34
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.
felix dot klee at inka dot de 27-Feb-2013 10:38
The code below illustrates usage of the second parameter, in particular to protect against fatal out-of-memory errors. It outputs:

1000000
1000000
error

Tested with PHP 5.3 on 32bit Linux.

<?php

function tryToGzinflate($deflatedData, $maxLen = 0) {
  $data = gzinflate($deflatedData, $maxLen);
  if ($data === false)
    echo 'error<br>';
  else
    echo strlen($data).'<br>';
}

// random data:
$data = '';
for ($i = 0; $i < 1000000; $i++)
  $data .= chr(mt_rand(97, 122)); // a-z

$deflatedData = gzdeflate($data);

ini_set('memory_limit', '5M'); // plenty of memory
tryToGzinflate($deflatedData);
tryToGzinflate($deflatedData, strlen($data));

ini_set('memory_limit', '100'); // little memory
tryToGzinflate($deflatedData, 100);
tryToGzinflate($deflatedData); // causes fatal out-of-memory error
?>
akniep at rayo dot info 11-Dec-2012 03:11
Take care when using the optional second parameter $length!
In our tests -at least in certain situations- we were unable to determine the actual use of this parameter, plus, it lead to the script either being unable to inflate compressed data or crash due to memory-problems.

Example:
When trying to inflate the compressed data from a website, we were literally unable to find a value (other than 0) for $length in order to make gzinflate work... while without the second parameter (or setting it to 0) gzinflate worked like a charm:

<?php
// -----------------------------------------------------------------------
// Test 1 works without problems. Memory peak usage: Before inflating: 24.787 kB; after: 24.844 kB.
gzinflate( substr($deflated_body, 10) );

// -----------------------------------------------------------------------
// ALL three of the following tests failed with a warning. Memory peak usage: Before inflating: 24.787 kB; after: 298.262 kB.
gzinflate( substr($deflated_body, 10),       200 * strlen($deflated_body) );
gzinflate( substr($deflated_body, 10),     32768 * strlen($deflated_body) );
gzinflate( substr($deflated_body, 10),     11000 );
gzinflate( substr($deflated_body, 10), 280000000 );    // the PHP memory limit was set to 300MB  (memory_limit=300M)
=>
Warning:  gzinflate() [function.gzinflate]: insufficient memory in [...]

// -----------------------------------------------------------------------
// The last test failed with a fatal error. Memory peak usage: Before inflating: 24.787 kB; after: ? (> 300M).
gzinflate( substr($deflated_body, 10), 300000000 );    // the PHP memory limit was set to 300MB  (memory_limit=300M)
=>
Fatal error:  Allowed memory size of 314572800 bytes exhausted (tried to allocate 300000000 bytes) in
?>

In short: We were unable to determine the actual use of the second parameter in certain situations.
Be careful with using the second parameter $length!
niblett at gmail dot com 07-Jun-2012 02:08
alternative, with detection for optional filename header
<?php
function gzdecode($data) {

        // check if filename field is set in FLG, is 4th byte
        $hex = bin2hex($data);

        $flg = (int)hexdec(substr($hex, 6, 2));

        // remove headers
        $hex = substr($hex, 20);

        $ret = '';
        if (  ($flg & 0x8) == 8 ){
                print "ello";
                for ( $i = 0; $i < strlen($hex); $i += 2 ){
                        $value = substr($hex, $i, 2);
                        if ( $value == '00' ){
                                $ret = substr($hex, ($i+2));
                                break;
                        }
                }
        }
        return gzinflate(pack('H*', $ret));
}
?>
Steven Lustig 05-Nov-2010 09:44
You can use this to uncompress a string from Linux command line gzip by stripping the first 10 bytes:

<?php
$inflatedOutput = gzinflate(substr($output, 10, -8));
?>
vitall at ua dot fm 09-Sep-2009 05:10
The correct function for gzip and chunked data particularly when you get "Content-Encoding: gzip" and "Transfer-Encoding: chunked" headers:

<?php
function decode_gzip($h,$d,$rn="\r\n"){
if (isset($h['Transfer-Encoding'])){
 $lrn = strlen($rn);
 $str = '';
 $ofs=0;
 do{
    $p = strpos($d,$rn,$ofs);
    $len = hexdec(substr($d,$ofs,$p-$ofs));
    $str .= substr($d,$p+$lrn,$len);
     $ofs = $p+$lrn*2+$len;
 }while ($d[$ofs]!=='0');
 $d=$str;
}
if (isset($h['Content-Encoding'])) $d = gzinflate(substr($d,10));
return $d;
}
?>

Enjoy!
John 12-Jun-2008 10:22
And when retrieving mod_deflate gzip'ed content and using gzinflate() to decode the data, be sure to strip the first 11 chars from the retrieved content.

<?php $dec = gzinflate(substr($enc,11)); ?>
patatraboum at free dot fr 24-Aug-2007 10:57
Some gz string strip header and return inflated
It actualy processes some first member of the gz
See rfc1952 at http://www.faqs.org/rfcs/rfc1952.html for more details and improvment as gzdecode

<?php
function gzBody($gzData){
    if(substr($gzData,0,3)=="\x1f\x8b\x08"){
        $i=10;
        $flg=ord(substr($gzData,3,1));
        if($flg>0){
            if($flg&4){
                list($xlen)=unpack('v',substr($gzData,$i,2));
                $i=$i+2+$xlen;
            }
            if($flg&8) $i=strpos($gzData,"\0",$i)+1;
            if($flg&16) $i=strpos($gzData,"\0",$i)+1;
            if($flg&2) $i=$i+2;
        }
        return gzinflate(substr($gzData,$i,-8));
    }
    else return false;
}
?>
spikeles_ at hotmail dot com 01-Nov-2006 08:12
This can be used to inflate streams compressed by the Java class java.util.zip.Deflater but you must strip the first 2 bytes off it. ( much like the above comment )

<?php $result = gzinflate(substr($compressedData, 2)); ?>
boris at gamate dot com 08-Jul-2003 05:49
When retrieving mod_gzip'ed content and using gzinflate() to decode the data, be sure to strip the first 10 chars from the retrieved content.

<?php $dec = gzinflate(substr($enc,10)); ?>
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