gzwrite

(PHP 4, PHP 5, PHP 7, PHP 8)

gzwrite — Ausgabe in gz-komprimierte Dateien

Beschreibung

gzwrite(resource $stream, string $data, ?int $length = null): int|false

gzwrite() schreibt den Inhalt von data in die angegebene gz-Datei aus.

Parameter-Liste

stream: Ein gz-Dateizeiger. Dieser muss gültig sein und auf eine Datei zeigen, die erfolgreich mit gzopen() geöffnet wurde.
data: Der auszugebende String.
length: Die Anzahl unkomprimierter Bytes, die ausgegeben werden sollen. Wenn angegeben, wird nach length aus data geschriebenen Bytes abgebrochen, wenn bis dahin das Ende des Strings nicht erreicht ist.

Rückgabewerte

Gibt die Anzahl der (unkomprimierten) Bytes zurück, die auf den gegebenen gz-Stream ausgegeben wurden. Bei einem Fehler wird false zurückgegeben..

Changelog

Version	Beschreibung
8.0.0	`length` ist jetzt ein Nullable-Typ; vorher war der Standardwert `0`.
7.4.0	Falls ein Fehler auftritt, gibt diese Funktion jetzt `false` zurück; vorher wurde `0` zurückgegeben.

Beispiele

Beispiel #1 gzwrite()-Beispiel

<?php
$string = 'Zu komprimierende Daten';
$gz = gzopen('somefile.gz','w9');
gzwrite($gz, $string);
gzclose($gz);
?>

Siehe auch

gzread() - Liest binary-safe aus einer gz-Datei
gzopen() - Öffnet eine gz-Datei

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User Contributed Notes 6 notes

down

calmarius at nospam dot atw dot hu ¶

15 years ago

gz compression is often used with tar archives. Building tar archives is quite easy. Here is a code snipplet which can be used for building tar archives before compressing them to tar.gz.

<?php

//\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
// Adds file header to the tar file, it is used before adding file content.
// f: file resource (provided by eg. fopen)
// phisfn: path to file
// archfn: path to file in archive, directory names must be followed by '/'
//\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
function TarAddHeader($f,$phisfn,$archfn)
{
    $info=stat($phisfn);
    $ouid=sprintf("%6s ", decoct($info[4]));
    $ogid=sprintf("%6s ", decoct($info[5]));
    $omode=sprintf("%6s ", decoct(fileperms($phisfn)));
    $omtime=sprintf("%11s", decoct(filemtime($phisfn)));
    if (@is_dir($phisfn))
    {
         $type="5";
         $osize=sprintf("%11s ", decoct(0));
    }
    else
    {
         $type='';
         $osize=sprintf("%11s ", decoct(filesize($phisfn)));
         clearstatcache();
    }
    $dmajor = '';
    $dminor = '';
    $gname = '';
    $linkname = '';
    $magic = '';
    $prefix = '';
    $uname = '';
    $version = '';
    $chunkbeforeCS=pack("a100a8a8a8a12A12",$archfn, $omode, $ouid, $ogid, $osize, $omtime);
    $chunkafterCS=pack("a1a100a6a2a32a32a8a8a155a12", $type, $linkname, $magic, $version, $uname, $gname, $dmajor, $dminor ,$prefix,'');

    $checksum = 0;
    for ($i=0; $i<148; $i++) $checksum+=ord(substr($chunkbeforeCS,$i,1));
    for ($i=148; $i<156; $i++) $checksum+=ord(' ');
    for ($i=156, $j=0; $i<512; $i++, $j++)    $checksum+=ord(substr($chunkafterCS,$j,1));

    fwrite($f,$chunkbeforeCS,148);
    $checksum=sprintf("%6s ",decoct($checksum));
    $bdchecksum=pack("a8", $checksum);
    fwrite($f,$bdchecksum,8);
    fwrite($f,$chunkafterCS,356);
    return true;
}
//\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
// Writes file content to the tar file must be called after a TarAddHeader
// f:file resource provided by fopen
// phisfn: path to file
//\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
function TarWriteContents($f,$phisfn)
{
    if (@is_dir($phisfn))
    {
        return;
    }
    else
    {
        $size=filesize($phisfn);
        $padding=$size % 512 ? 512-$size%512 : 0;
        $f2=fopen($phisfn,"rb");
        while (!feof($f2)) fwrite($f,fread($f2,1024*1024));
        $pstr=sprintf("a%d",$padding);
        fwrite($f,pack($pstr,''));
    }
}
//\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
// Adds 1024 byte footer at the end of the tar file
// f: file resource
//\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
function TarAddFooter($f)
{
    fwrite($f,pack('a1024',''));
}

?>

down

Kioob ¶

21 years ago

This is a short example of use gzwrite function. 

<?php

function gzcompressfile($source,$level=false){

    $dest=$source.'.gz';

    $mode='wb'.$level;

    $error=false;

    if($fp_out=gzopen($dest,$mode)){

        if($fp_in=fopen($source,'rb')){

            while(!feof($fp_in))

                gzwrite($fp_out,fread($fp_in,1024*512));

            fclose($fp_in);

            }

          else $error=true;

        gzclose($fp_out);

        }

      else $error=true;

    if($error) return false;

      else return $dest;

    }

?>



the function gzcompressfile() compress a file 'data.csv' to 'data.csv.gz'. the function return false if error, and the new file name if it's ok.

down

Take Heed ¶

14 years ago

Read the description of gzwrite() very carefully.  If the 'length' option is not specified, then the input data will have slashes stripped on systems where magic quotes are enabled.  This is important information to know when compressing files.



<?php

$data = fread($fp, 5000);

gzwrite($fp2, $data, strlen($data));

?>



Is the correct way to avoid issues with magic quotes.

down

Anonymous ¶

16 years ago

katzlbtjunk's method is certainly shorter, but it is unusable for anything except small files.  It would try to load the whole file into memory, then create an entire compressed copy, and only then write it to disk.  The other method given below will not exhaust memory like that.

down

-3

repository at lamaresh dot net ¶

15 years ago

This function add a line to a .gz compressed file



<?php

function AppendLineGz($file,$string) {

    if (file_exists($file)) {

        $lines = gzfile($file);

        $lines[count($lines)] = "$string\r\n";

        $input=implode($lines);

    } else {$input="$string\r\n";}

    $gz = gzopen($file,'w9');

    gzwrite($gz, $input);

    gzclose($gz);    

}

?>

down

-4

katzlbtjunk at hotmail dot com ¶

16 years ago

How about this instead:
$s = file_get_contents('file.tar'); 
file_put_contents('file.tar.gz',gzencode($s,9));

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