gzinflate

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

    gzinflate — deflate圧縮された文字列を解凍する

    説明

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

    この関数は圧縮された文字列を解凍(伸長)します。

    パラメータ

    data

    gzdeflate() により圧縮されたデータを指定します

    max_length

    解凍されたデータの最大長を指定します

    戻り値

    オリジナルの無圧縮なデータ、もしくはエラー時に false

    この関数は、もし無圧縮なデータが圧縮された入力 data の 32768 倍以上の場合、エラーを返します。 また、オプションのパラメータ max_length に 0 以外が指定された場合、 無圧縮なデータが max_length 以上の場合、エラーを返します。

    例

    例1 gzinflate() の例

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

    参考

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    User Contributed Notes 10 notes

    up
    35
    anonymous at dekho-ji dot com
    11 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
    15 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
    14 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
    21 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
    17 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
    18 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
    12 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
    12 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
    16 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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