Creating zip files dynamically can be quite useful under a number of circumstances. When I first had a need to do this I found an article at Zend.com (Creating Zip Files Dynamically) that covered this topic. The original code was designed to zip text passed as a string. I needed something that would allow me to zip existing files on the filesystem. The resulting code is below. In the time since I made these original modifications, the discussion has continued on the article page, so you may want to check it out. You could easily combine my updated code with the original to support both text and filesystem encoding. It may already be done on the site. Code:


< ?php // Class definition found at http://www.zend.com/zend/spotlight/creating-zip-files3.php // Some alterations to the original posted code were made in order to get everything working properly // See example usage at the bottom of this page class zipfile { var $datasec = array(); var $ctrl_dir = array(); var $eof_ctrl_dir = "\x50\x4b\x05\x06\x00\x00\x00\x00"; var $old_offset = 0; function add_dir($name) { $name = str_replace("", "/", $name); $fr = "\x50\x4b\x03\x04"; $fr .= "\x0a\x00"; $fr .= "\x00\x00"; $fr .= "\x00\x00"; $fr .= "\x00\x00\x00\x00"; $fr .= pack("V",0); $fr .= pack("V",0); $fr .= pack("V",0); $fr .= pack("v", strlen($name) ); $fr .= pack("v", 0 ); $fr .= $name; $fr .= pack("V", 0); $fr .= pack("V", 0); $fr .= pack("V", 0); $this -> datasec[] = $fr;
$new_offset = strlen(implode("", $this->datasec));

$cdrec = "\x50\x4b\x01\x02";
$cdrec .="\x00\x00";
$cdrec .="\x0a\x00";
$cdrec .="\x00\x00";
$cdrec .="\x00\x00";
$cdrec .="\x00\x00\x00\x00";
$cdrec .= pack("V",0);
$cdrec .= pack("V",0);
$cdrec .= pack("V",0);
$cdrec .= pack("v", strlen($name) );
$cdrec .= pack("v", 0 );
$cdrec .= pack("v", 0 );
$cdrec .= pack("v", 0 );
$cdrec .= pack("v", 0 );
$ext = "\x00\x00\x10\x00";
$ext = "\xff\xff\xff\xff";
$cdrec .= pack("V", 16 );
$cdrec .= pack("V", $this -> old_offset );
$cdrec .= $name;

$this -> ctrl_dir[] = $cdrec;
$this -> old_offset = $new_offset;
return;
}

function add_file($data, $name) {
$fp = fopen($data,"r");
$data = fread($fp,filesize($data));
fclose($fp);
$name = str_replace("", "/", $name);
$unc_len = strlen($data);
$crc = crc32($data);
$zdata = gzcompress($data);
$zdata = substr ($zdata, 2, -4);
$c_len = strlen($zdata);
$fr = "\x50\x4b\x03\x04";
$fr .= "\x14\x00";
$fr .= "\x00\x00";
$fr .= "\x08\x00";
$fr .= "\x00\x00\x00\x00";
$fr .= pack("V",$crc);
$fr .= pack("V",$c_len);
$fr .= pack("V",$unc_len);
$fr .= pack("v", strlen($name) );
$fr .= pack("v", 0 );
$fr .= $name;
$fr .= $zdata;
$fr .= pack("V",$crc);
$fr .= pack("V",$c_len);
$fr .= pack("V",$unc_len);

$this -> datasec[] = $fr;
$new_offset = strlen(implode("", $this->datasec));

$cdrec = "\x50\x4b\x01\x02";
$cdrec .="\x00\x00";
$cdrec .="\x14\x00";
$cdrec .="\x00\x00";
$cdrec .="\x08\x00";
$cdrec .="\x00\x00\x00\x00";
$cdrec .= pack("V",$crc);
$cdrec .= pack("V",$c_len);
$cdrec .= pack("V",$unc_len);
$cdrec .= pack("v", strlen($name) );
$cdrec .= pack("v", 0 );
$cdrec .= pack("v", 0 );
$cdrec .= pack("v", 0 );
$cdrec .= pack("v", 0 );
$cdrec .= pack("V", 32 );
$cdrec .= pack("V", $this -> old_offset );

$this -> old_offset = $new_offset;

$cdrec .= $name;
$this -> ctrl_dir[] = $cdrec;
}

function file() {
$data = implode("", $this -> datasec);
$ctrldir = implode("", $this -> ctrl_dir);

return
$data .
$ctrldir .
$this -> eof_ctrl_dir .
pack("v", sizeof($this -> ctrl_dir)) .
pack("v", sizeof($this -> ctrl_dir)) .
pack("V", strlen($ctrldir)) .
pack("V", strlen($data)) .
"\x00\x00";
}
}

// Test this class
$zipTest = new zipfile();
$zipTest->add_dir("images/");
$zipTest->add_file("images/box1.jpg", "images/box1.jpg");
$zipTest->add_file("images/box2.jpg", "images/box2.jpg");

// Return Zip File to Browser
Header("Content-type: application/octet-stream");
Header ("Content-disposition: attachment; filename=zipTest.zip");
echo $zipTest->file();

// Alternatively, you can write the file to the file system and provide a link:
/*
$filename = "output.zip";
$fd = fopen ($filename, "wb");
$out = fwrite ($fd, $zipTest -> file());
fclose ($fd);

echo "Click here to download the new zip file.";
*/

?>