gzwrite

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

gzwrite — Escrita segura para binário em arquivo-gz

Descrição

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

gzwrite() escreve o conteúdo de data para o arquivo-gz.

Parâmetros

stream: O ponteiro do arquivo gz. Precisa ser válido, e apontar para um arquivo aberto com sucesso por gzopen().
data: A string a ser escrita.
length: O número de bytes descomprimidos para escrever. Se fornecido, a escrita irá parar depois de length (descomprimido) bytes ter sido escritos, ou ao final de data, o que vier primeiro.

Valor Retornado

Retorna o número de (descomprimido) bytes escrito no dado stream do arquivo gz, ou false em caso de falha.

Registro de Alterações

Versão	Descrição
8.0.0	`length` permite null; anteriormente o default era `0`.
7.4.0	Esta função agora retorna `false` em caso de falha; anteriormente retornava `0`.

Exemplos

Exemplo #1 Exemplo da gzwrite()

<?php
$string = 'Some information to compress';
$gz = gzopen('somefile.gz','w9');
gzwrite($gz, $string);
gzclose($gz);
?>

Veja Também

gzread() - Leitura de arquivo gz binária segura
gzopen() - Abre arquivo gz

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Notas Enviadas por Usuários (em inglês) 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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