Crear archivos comprimidos en ZIP

Crear archivos comprimidos en drupal es muy fácil, sólo hace falta introducir en el módulo el archivo zip.inc y algo de programación.

En las líneas que se añaden en ejemplo.module se tiene que especificar el archivo o archivos a comprimir y el nombre del fichero zip. En este ejemplo los archivos a comprimir son foto1.jpg y foto2.jpg y el zip resultante es fotos_comprimidas.zip

Basado en el artículo de Michael.M: Creating ZIP files

ejemplo.module:

<?php
require_once("./includes/zip.inc");
$zip = new zipfile();
$files_to_zip = array('foto1.jpg', 'foto2.doc');
foreach ($files_to_zip as $filename) {
$zip->addFile(file_get_contents(file_create_path($filename)), $filename); // the second parameter specifies the filename in the zip
}
if (!file_save_data($zip->file(), file_create_path('fotos_comprimidas.zip'))) {
drupal_set_message(t('The zip could not be created.'), 'error');
}
?>

zip.inc:

<?php
/* $Id: zip.lib.php,v 2.4 2004/11/03 13:56:52 garvinhicking Exp $ */
// vim: expandtab sw=4 ts=4 sts=4:
/**
* Zip file creation class.
* Makes zip files.
*
* Based on :
*
* http://www.zend.com/codex.php?id=535&single=1
* By Eric Mueller
*
* http://www.zend.com/codex.php?id=470&single=1
* by Denis125
*
* a patch from Peter Listiak for last modified
* date and time of the compressed file
*
* Official ZIP file format: http://www.pkware.com/appnote.txt
*
* @access public
*/
class zipfile
{
/**
* 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;

/**
* 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 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 'unix2DosTime()' method

/**
* Adds "file" to archive
*
* @param string file contents
* @param string name of the file in the archive (may contains the path)
* @param integer the current timestamp
*
* @access public
*/
function addFile($data, $name, $time = 0)
{
$name = str_replace('\\', '/', $name);

$dtime = dechex($this->unix2DosTime($time));
$hexdtime = '\x' . $dtime[6] . $dtime[7]
. '\x' . $dtime[4] . $dtime[5]
. '\x' . $dtime[2] . $dtime[3]
. '\x' . $dtime[0] . $dtime[1];
eval('$hexdtime = "' . $hexdtime . '";');

$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;

// "data descriptor" segment (optional but necessary if archive is not
// served as file)
// nijel(2004-10-19): this seems not to be needed at all and causes
// problems in some cases (bug #1037737)
//$fr .= pack('V', $crc); // crc32
//$fr .= pack('V', $c_len); // compressed filesize
//$fr .= pack('V', $unc_len); // uncompressed filesize

// 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 'addFile()' method

/**
* Dumps out file
*
* @return string the zipped file
*
* @access public
*/
function file()
{
$data = implode('', $this -> datasec);
$ctrldir = implode('', $this -> ctrl_dir);

return
$data .
$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', strlen($data)) . // offset to start of central dir
"\x00\x00"; // .zip file comment length
} // end of the 'file()' method

}?>