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gzinflate

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

gzinflateDécompresse une chaîne

Description

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

gzinflate() décompresse une chaîne.

Liste de paramètres

data

Les données compressées avec la fonction gzdeflate().

max_length

La longueur maximale de données décodé.

Valeurs de retour

Les données originales décompressées ou false si une erreur survient.

gzinflate() retourne une erreur si la chaîne décompressée est plus de 32768 fois plus longue que la chaîne compressée data ou, sauf si max_length est 0, plus grande que la taille de max_length octets, passé comme paramètre optionnel.

Exemples

Exemple #1 Exemple avec gzinflate()

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

Voir aussi

add a note

User Contributed Notes 10 notes

up
35
anonymous at dekho-ji dot com
10 years 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
5
felix dot klee at inka dot de
11 years ago
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
?>
up
8
vitall at ua dot fm
14 years ago
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!
up
7
Steven Lustig
13 years ago
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));
?>
up
4
boris at gamate dot com
20 years ago
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)); ?>
up
5
patatraboum at free dot fr
16 years ago
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;
}
?>
up
3
spikeles_ at hotmail dot com
17 years ago
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)); ?>
up
1
niblett at gmail dot com
11 years ago
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));
}
?>
up
1
akniep at rayo dot info
11 years ago
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!
up
-4
John
15 years ago
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)); ?>
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