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<?php
#
# ZipStream - Streamed, dynamically generated zip archives.
# Paul Duncan <pabs@pablotron.org>
#
# Usage:
#
# # create a new zip stream object
# $zs = new ZipStream();
#
# # list of local files
# $files = array('foo.txt', 'bar.jpg');
#
# # read and add each file to the archive
# foreach ($files as $path)
# $zs->add_file($path, file_get_contents($path));
#
# # write archive footer to stream
# $zs->finish();
#
class ZipStream {
var $files = array(),
$cdr_ofs = 0,
$ofs = 0;
function ZipStream($name = 'untitled.zip', $send_http_headers = false) {
$this->output_name = $name;
$this->need_headers = $send_http_headers;
}
#
# add_file - add a file to the archive
#
# Parameters:
#
# $name - path of file in archive (including directory).
# $data - contents of file
# $time - last-modified timestamp of file (optional)
#
# Example:
#
# $data = file_get_contents('foo.txt');
# $zs->add_file('foo.txt', $data);
#
function add_file($name, $data, $time = 0) {
# compress data
$zdata = substr(gzcompress($data), 2, -4);
# calculate header attributes
$crc = crc32($data);
$zlen = strlen($zdata);
$nlen = strlen($name);
$len = strlen($data);
# TODO: create unix timestamp
# build file header
$fields = array( # (from V.A of APPNOTE.TXT)
array('V', 0x04034b50), # local file header signature
array('v', 0x14), # version needed to extract
array('v', 0x00), # general purpose bit flag
array('v', 0x08), # compresion method (deflate)
array('v', 0x00), # file mod time (dos) FIXME
array('v', 0x00), # file mod date (dos) FIXME
array('V', $crc), # crc32 of data
array('V', $zlen), # compressed data length
array('V', $len), # uncompressed data length
array('v', $nlen), # filename length
array('v', 0), # extra data len
);
# pack fields
$ret = $this->pack_fields($fields) . $name . $zdata;
# add to central directory record and increment offset
$this->add_to_cdr($name, $time, $crc, $zlen, $len, strlen($ret));
# print data
$this->send($ret);
}
#
# finish - Write zip footer to stream.
#
# Example:
#
# # add a list of files to the archive
# $files = array('foo.txt', 'bar.jpg');
# foreach ($files as $path)
# $zs->add_file($path, file_get_contents($path));
#
# # write footer to stream
# $zs->finish();
#
function finish() {
$this->add_cdr();
$this->clear();
}
function send_http_headers($name = 'untitled.zip') {
$headers = array(
'Content-Type' => 'application/x-zip',
'Content-Disposition' => "attachment; filename=\"{$name}\"",
'Pragma' => 'public',
'Cache-Control' => 'public, must-revalidate',
'Content-Transfer-Encoding' => 'binary',
);
foreach ($headers as $key => $val)
header("$key: $val");
}
###################
# PRIVATE METHODS #
###################
function add_to_cdr($name, $time, $crc, $zlen, $len, $rec_len) {
$this->files[] = array($name, $time, $crc, $zlen, $len, $this->ofs);
$this->ofs += $rec_len;
}
function add_cdr_file($args) {
list ($name, $time, $crc, $zlen, $len, $ofs) = $args;
$fields = array( # (from V,F of APPNOTE.TXT)
array('V', 0x02014b50), # central file header signature
array('v', 0x00), # version made by
array('v', 0x14), # version needed to extract
array('v', 0x00), # general purpose bit flag
array('v', 0x08), # compresion method (deflate)
array('v', 0x00), # file mod time (dos) FIXME
array('v', 0x00), # file mod date (dos) FIXME
array('V', $crc), # crc32 of data
array('V', $zlen), # compressed data length
array('V', $len), # uncompressed data length
array('v', $nlen), # filename length
array('v', 0), # extra data len
array('v', 0), # file comment length
array('v', 0), # disk number start
array('v', 0), # internal file attributes
array('V', 32), # external file attributes
array('V', $ofs), # relative offset of local header
);
# pack fields and append name
$ret = $this->pack_fields($fields) . $name;
$this->send($ret);
# increment cdr offset
$this->cdr_ofs += strlen($ret);
}
function add_cdr_eof() {
$num = count($this->files);
$cdr_len = $this->cdr_ofs;
$cdr_ofs = $this->ofs;
$fields = array( # (from V,F of APPNOTE.TXT)
array('V', 0x06054b50), # end of central file header signature
array('v', 0x00), # this disk number
array('v', 0x00), # number of disk with cdr
array('v', $num), # number of entries in the cdr on this disk
array('v', $num), # number of entries in the cdr
array('V', $cdr_len), # cdr size
array('V', $cdr_ofs), # cdr ofs
array('v', 0x00), # zip file comment length
);
$ret = $this->pack_fields($fields);
$this->send($ret);
}
function add_cdr() {
foreach ($this->files as $file)
$this->add_cdr_file($file);
$this->add_cdr_eof();
}
function clear() {
$this->files = array();
$this->ofs = 0;
$this->cdr_ofs = 0;
}
function send($str) {
if ($this->need_headers)
$this->send_http_headers($this->output_name);
$this->need_headers = false;
echo $str;
}
function pack_fields($fields) {
list ($fmt, $args) = array('', array());
# populate format string and argument list
foreach ($fields as $field) {
$fmt .= $field[0];
$args[] = $field[1];
}
# prepend format string to argument list
array_unshift($args, $fmt);
# build output string from header and compressed data
return call_user_func_array('pack', $args);
}
};
?>
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