gzinflate
(PHP 4 >= 4.0.4, PHP 5, PHP 7)
gzinflate — Распаковывает строку
Описание
string gzinflate
( string
$data
[, int $length = 0
] )Распаковывает сжатую строку.
Список параметров
-
data -
Данные, сжатые функцией gzdeflate().
-
length -
Максимальный размер данных для распаковки.
Возвращаемые значения
Распакованные данные или FALSE в случае ошибки.
Функция также сообщит об ошибке в случае, если несжатые данные в
32768 раз больше размера сжатых данных data или
больше параметра length.
Примеры
Пример #1 Пример использования gzinflate()
<?php
$compressed = gzdeflate('Сожми меня', 9);
$uncompressed = gzinflate($compressed);
echo $uncompressed;
?>
Смотрите также
- gzdeflate() - Сжимает строку
- gzcompress() - Сжимает строку
- gzuncompress() - Распаковывает строку
- gzencode() - Сжимает строку в формате gzip
Коментарии
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)); ?>
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)); ?>
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;
}
?>
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)); ?>
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!
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));
?>
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));
}
?>
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 $length!
The code below illustrates usage of the second parameter, in particular to protect against fatal out-of-memory errors. It outputs:
1000000
1000000
error
Tested with PHP 5.3 on 32bit Linux.
<?php
function tryToGzinflate($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($deflatedData); // causes fatal out-of-memory error
?>
To decode / uncompress the received HTTP POST data in PHP code, request data coming from Java / Android application via HTTP POST GZIP / DEFLATE compressed format
1) Data sent from Java Android app to PHP using DeflaterOutputStream java class and received in PHP as shown below
echo gzinflate( substr($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.