PHPのお勉強！

PHP TOP
PHP 8.4.2 Released!

    gzuncompress

    (PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)

    gzuncompress — 圧縮された文字列を解凍する

    説明

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

    この関数は圧縮された文字列を解凍します。

    パラメータ

    data

    gzcompress() によって圧縮されたデータを指定します。

    max_length

    デコードする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、もしくはオプションのパラメータ max_length 以上の場合、エラーを返します。

    例

    例1 gzuncompress() の例

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

    参考

    Found A Problem?

    Learn How To Improve This Page • Submit a Pull Request • Report a Bug
    ＋add a note

    User Contributed Notes 7 notes

    up
    16
    heavyccasey at gmail dot com
    17 years ago
    Note that gzuncompress() may not decompress some compressed strings and return a Data Error.

    The problem could be that the outside compressed string has a CRC32 checksum at the end of the file instead of Adler-32, like PHP expects.

    Workaround:
    <?php
    function gzuncompress_crc32($data) {
    $f = tempnam('/tmp', 'gz_fix');
    file_put_contents($f, "\x1f\x8b\x08\x00\x00\x00\x00\x00" . $data);
    return     file_get_contents('compress.zlib://' . $f);
    }
    ?>
    up
    14
    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
    6
    MagicalTux at php dot net
    13 years ago
    Hi, I got an alternative for those zipped strings that gzuncompress() cannot extract.

    It is a bit better than previous options as it do not create any temporary files, but it has to encode the string in base64, meaning it won't be as fast as a native equivalent (which is probably going to be gzdecode())

    <?php
    if (!function_exists('gzdecode')) {
    function     gzdecode($string) { // no support for 2nd argument
    return file_get_contents('compress.zlib://data:who/cares;base64,'. base64_encode($string));
    }
    }
    ?>
    up
    4
    gabriel at bumpt dot n-et
    17 years ago
    To uncompress in PHP a string that has been compressed using MySQL's COMPRESS() function, you need to discard the first four bytes of the binary data:

    <?php

    /*
    * Example:
    *
    * insert into mytable (myfield, ...) values (COMPRESS('foobar'), ...)
    *
    * then:
    */
    $compressed = //...select myfield from mytable where...
    /*
    * then:
    */
    $uncompressed = gzuncompress(substr($compressed, 4));
    ?>

    Of course, you can use MySQL's UNCOMPRESS() function.
    I was just providing an alternate method.
    up
    2
    squeegee
    15 years ago
    One way to uncompress zlib-compressed data that is in a file without first reading in the file and then gzuncompressing it (maybe you have memory problems doing it that way) is to compile the zpipe.c program from zlib ( http://www.zlib.net/zpipe.c )...

    on linux, etc:

    # gcc -lz -o zpipe zpipe.c

    # cp zpipe /usr/local/bin

    Then do this

    <?php

    $uncompressed     = shell_exec("cat $compressed_file | zpipe -d");

    ?>
    up
    0
    emanuele at fondani dot it
    18 years ago
    Note that the manual states that the input parameter must be a string compressed with gzcompress(), so it is not guaranteed that it will compress ANY zlib compressed string.
    I realized this while decompressing some compressed string in a pdf file. The gzuncompress() function produces a data error, but the string can be successfully decompressed with other zlib decompressors.

    More info here:
    http://bugs.php.net/?id=39616
    up
    -2
    chappy at citromail dot hu
    18 years ago
    Reading an ID3v2.3+ tag it is versy useful, because these tag's frames might be compressed. Zlib compressed frame layout (ID3v2.3):

    Descriptior Size
    -------------------
    Frameheader:
    Frame id: 4 bytes
    Frame size (full frame size - frameheader size): 4 bytes
    Frame flags: 2 bytes
    The 2nd byte's 7th bit must be 1 (e.g.: %1xy00000)
    Frame content decrompessed size: 4 bytes
    --------------------
    Framecontent:
    Compressed string described in 'frame size'

    <?php
    $frame    ="[read from a mp3 file]";
    $frame_id=substr($frame,0,4);
    /*....*/
    $cs=substr($frame,10,4);
    $checksize=$cs[3]*16777216+$cs[2]*65536+$cs[1]*256+$cs[0];

    $content=substr($frame,14,$contentsize);
    $content=gzuncompress($content);
    if(    strlen($content)!=$checksize){
    echo     'Error whil uncrompessing frame data<br>';
    }
    echo     $content;
    ?>
    ＋add a note
    To Top