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gzwrite

(PHP 4, PHP 5)

gzwriteBinary-safe gz-file write

Description

int gzwrite ( resource $zp , string $string [, int $length ] )

gzwrite() writes the contents of string to the given gz-file.

Parameters

zp

The gz-file pointer. It must be valid, and must point to a file successfully opened by gzopen().

string

The string to write.

length

The number of uncompressed bytes to write. If supplied, writing will stop after length (uncompressed) bytes have been written or the end of string is reached, whichever comes first.

Note:

Note that if the length argument is given, then the magic_quotes_runtime configuration option will be ignored and no slashes will be stripped from string.

Return Values

Returns the number of (uncompressed) bytes written to the given gz-file stream.

Examples

Example #1 gzwrite() example

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

See Also

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User Contributed Notes 6 notes

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2
Kioob
11 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.
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1
calmarius at nospam dot atw dot hu
5 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',''));
}

?>
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0
Take Heed
3 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.
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0
repository at lamaresh dot net
5 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);   
}
?>
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0
Anonymous
6 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.
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-1
katzlbtjunk at hotmail dot com
6 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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