Create Zip Archive for download in memory(without using file system)

gistfile1.txt

sometimes we don't want to make any usage to the hardisk, when we just want to grab something from remote server, and make a Zip archive for download, and the offical php ZipArchive module don't support this till now, so here is a class to make this(from phpMyAdmin library).

Here is sample usage:

require_once('zip.lib.php');

//create the zip
$zip = new zipfile();

//add files to the zip, passing file contents, not actual files
$zip->addFile($file_content, $file_name);
...

//prepare the proper content type
header("Content-type: application/octet-stream");
header("Content-Disposition: attachment; filename=my_archive.zip");
header("Content-Description: Files of an applicant");

//get the zip content and send it back to the browser
echo $zip->file();

zip.lib.php

<?php
/**
 * Zip file creation
 *
 * @package PhpMyAdmin
 */

/**
 * Zip file creation class.
 * Makes zip files.
 *
 * @access  public
 * @package PhpMyAdmin
 * @see     Official ZIP file format: http://www.pkware.com/support/zip-app-note
 */
class ZipFile
{
    /**
     * Whether to echo zip as it's built or return as string from -> file
     *
     * @var  boolean $doWrite
     */
    var $doWrite = false;
    /**
     * Array to store compressed data
     *
     * @var  array $datasec
     */
    var $datasec = array();
    /**
     * Central directory
     *
     * @var  array $ctrl_dir
     */
    var $ctrl_dir = array();
    /**
     * End of central directory record
     *
     * @var  string $eof_ctrl_dir
     */
    var $eof_ctrl_dir = "\x50\x4b\x05\x06\x00\x00\x00\x00";
    /**
     * Last offset position
     *
     * @var  integer $old_offset
     */
    var $old_offset = 0;

    /**
     * Sets member variable this -> doWrite to true
     * - Should be called immediately after class instantiation
     * - If set to true, then ZIP archive are echo'ed to STDOUT as each
     *   file is added via this -> addfile(), and central directories are
     *   echoed to STDOUT on final call to this -> file().  Also,
     *   this -> file() returns an empty string so it is safe to issue a
     *   "echo $zipfile;" command
     *
     * @access public
     *
     * @return void
     */
    function setDoWrite() {
        $this->doWrite = true;
    } // end of the 'setDoWrite()' method

    /**
     * Adds "file" to archive
     *
     * @param string $data file contents
     * @param string $name name of the file in the archive (may contains the path)
     * @param integer $time the current timestamp
     *
     * @access public
     *
     * @return void
     */
    function addFile($data, $name, $time = 0) {
        $name     = str_replace('\\', '/', $name);
        $hexdtime = pack('V', $this->unix2DosTime($time));
        $fr       = "\x50\x4b\x03\x04";
        $fr .= "\x14\x00";            // ver needed to extract
        $fr .= "\x00\x00";            // gen purpose bit flag
        $fr .= "\x08\x00";            // compression method
        $fr .= $hexdtime;             // last mod time and date
        // "local file header" segment
        $unc_len = strlen($data);
        $crc     = crc32($data);
        $zdata   = gzcompress($data);
        $zdata   = substr(substr($zdata, 0, strlen($zdata) - 4), 2); // fix crc bug
        $c_len   = strlen($zdata);
        $fr .= pack('V', $crc);             // crc32
        $fr .= pack('V', $c_len);           // compressed filesize
        $fr .= pack('V', $unc_len);         // uncompressed filesize
        $fr .= pack('v', strlen($name));    // length of filename
        $fr .= pack('v', 0);                // extra field length
        $fr .= $name;
        // "file data" segment
        $fr .= $zdata;
        // echo this entry on the fly, ...
        if ($this->doWrite) {
            echo $fr;
        } else {                     // ... OR add this entry to array
            $this->datasec[] = $fr;
        }
        // now add to central directory record
        $cdrec = "\x50\x4b\x01\x02";
        $cdrec .= "\x00\x00";                // version made by
        $cdrec .= "\x14\x00";                // version needed to extract
        $cdrec .= "\x00\x00";                // gen purpose bit flag
        $cdrec .= "\x08\x00";                // compression method
        $cdrec .= $hexdtime;                 // last mod time & date
        $cdrec .= pack('V', $crc);           // crc32
        $cdrec .= pack('V', $c_len);         // compressed filesize
        $cdrec .= pack('V', $unc_len);       // uncompressed filesize
        $cdrec .= pack('v', strlen($name)); // length of filename
        $cdrec .= pack('v', 0);             // extra field length
        $cdrec .= pack('v', 0);             // file comment length
        $cdrec .= pack('v', 0);             // disk number start
        $cdrec .= pack('v', 0);             // internal file attributes
        $cdrec .= pack('V', 32);            // external file attributes
        // - 'archive' bit set
        $cdrec .= pack('V', $this->old_offset); // relative offset of local header
        $this->old_offset += strlen($fr);
        $cdrec .= $name;
        // optional extra field, file comment goes here
        // save to central directory
        $this->ctrl_dir[] = $cdrec;
    } // end of the 'unix2DosTime()' method

    /**
     * Converts an Unix timestamp to a four byte DOS date and time format (date
     * in high two bytes, time in low two bytes allowing magnitude comparison).
     *
     * @param integer $unixtime the current Unix timestamp
     *
     * @return integer the current date in a four byte DOS format
     *
     * @access private
     */
    function unix2DosTime($unixtime = 0) {
        $timearray = ($unixtime == 0) ? getdate() : getdate($unixtime);
        if ($timearray['year'] < 1980) {
            $timearray['year']    = 1980;
            $timearray['mon']     = 1;
            $timearray['mday']    = 1;
            $timearray['hours']   = 0;
            $timearray['minutes'] = 0;
            $timearray['seconds'] = 0;
        } // end if
        return (($timearray['year'] - 1980) << 25)
        | ($timearray['mon'] << 21)
        | ($timearray['mday'] << 16)
        | ($timearray['hours'] << 11)
        | ($timearray['minutes'] << 5)
        | ($timearray['seconds'] >> 1);
    } // end of the 'addFile()' method

    /**
     * Echo central dir if ->doWrite==true, else build string to return
     *
     * @return string  if ->doWrite {empty string} else the ZIP file contents
     *
     * @access public
     */
    function file() {
        $ctrldir = implode('', $this->ctrl_dir);
        $header  = $ctrldir .
            $this->eof_ctrl_dir .
            pack('v', sizeof($this->ctrl_dir)) . //total #of entries "on this disk"
            pack('v', sizeof($this->ctrl_dir)) . //total #of entries overall
            pack('V', strlen($ctrldir)) .          //size of central dir
            pack('V', $this->old_offset) .       //offset to start of central dir
            "\x00\x00";                            //.zip file comment length
        if ($this->doWrite) { // Send central directory & end ctrl dir to STDOUT
            echo $header;
            return "";            // Return empty string
        } else {                  // Return entire ZIP archive as string
            $data = implode('', $this->datasec);
            return $data . $header;
        }
    } // end of the 'file()' method
} // end of the 'ZipFile' class

THANK YOU