gzwrite

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

gzwrite — Écrit dans un fichier compressé gzip

Description

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

gzwrite() écrit le contenu de la chaîne data dans le fichier compressé zp.

Liste de paramètres

stream: Le pointeur de fichier. Il doit être valide et doit pointer vers un fichier ouvert avec succès grâce à la fonction gzopen().
data: La chaîne à écrire.
length: Le nombre d'octets décompressés à écrire. Si fournie, l'écriture s'arrêtera après length (décompressé) octets écrits ou si la fin de la chaîne data est atteinte ; celui qui survient le premier.

Valeurs de retour

Retourne le nombre d'octets (décompressés) écrits dans le flux gz donné, ou false si une erreur survient.

Historique

Version	Description
8.0.0	`length` est désormais nullable; auparavant la valeur par défaut était `0`.
7.4.0	Cette fonction retourne désormais `false` en cas d'échec; auparavant `0` était retourné.

Exemples

Exemple #1 Exemple avec gzwrite()

<?php
$string = 'Quelques informations à compresser';
$gz = gzopen('somefile.gz','w9');
gzwrite($gz, $string);
gzclose($gz);
?>

Voir aussi

gzread() - Lecture de fichier compressé binaire
gzopen() - Ouvre un fichier compressé avec gzip

Improve This Page

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

＋add a note

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));

＋add a note