PHP ZIP files on the fly

Question

What's the easiest way to zip, say 2 files, from a folder on the server and force download? Without saving the "zip" to the server.

    $zip = new ZipArchive();
   //the string "file1" is the name we're assigning the file in the archive
$zip->addFile(file_get_contents($filepath1), 'file1'); //file 1 that you want compressed
$zip->addFile(file_get_contents($filepath2), 'file2'); //file 2 that you want compressed
$zip->addFile(file_get_contents($filepath3), 'file3'); //file 3 that you want compressed
echo $zip->file(); //this sends the compressed archive to the output buffer instead of writing it to a file.

Can someone verify: I have a folder with test1.doc, test2.doc, and test3.doc

with the above example - file1 (file2 and file3) might just be test1.doc, etc.

do I have to do anything with "$filepath1"? Is that the folder directory that holds the 3 docs?

Sorry for my basic question..

Answer 1

Unfortunately w/ PHP 5.3.4-dev and Zend Engine v2.3.0 on CentOS 5.x I couldn't get the code above to work. An "Invalid or unitialized Zip object" error message was all I could get. So, in order to make it work, I had to use following snippet (taken from the example by Jonathan Baltazar on PHP.net manual, at the ZipArchive::open page):

// Prepare File
$file = tempnam("tmp", "zip");
$zip = new ZipArchive();
$zip->open($file, ZipArchive::OVERWRITE);

// Stuff with content
$zip->addFromString('file_name_within_archive.ext', $your_string_data);
$zip->addFile('file_on_server.ext', 'second_file_name_within_archive.ext');

// Close and send to users
$zip->close();
header('Content-Type: application/zip');
header('Content-Length: ' . filesize($file));
header('Content-Disposition: attachment; filename="file.zip"');
readfile($file);
unlink($file); 

I know this is different than working w/ memory only - unless you have your tmp area in ram ;-) - but maybe this can help out someone else, who's struggling with the solution above, like I was; and for which performance penalty is not an issue.

Answer 2

Your code is very close. You need to use the file name instead of the file contents.

$zip->addFile(file_get_contents($filepath1), 'file1');

should be

$zip->addFile($filepath1, 'file1');

http://us3.php.net/manual/en/function.ziparchive-addfile.php

If you need to add files from a variable instead of a file you can use the addFromString function.

$zip->addFromString( 'file1', $data );

Answer 3

If you have access to the zip commandline utility you can try

<?php
$zipped_data = `zip -q - files`;
header('Content-type: application/zip');
header('Content-Disposition: attachment; filename="download.zip"');
echo $zipped_data;
?>

where files is the things you want to zip and zip the location to the zip executable.

This assumes Linux or similar, of course. In Windows you might be able to do similar with another compression tool, I guess.

There's also a zip extension, usage shown here.

Answer 4

This works for me (nothing is written to disk)

$tmp_file = tmpfile(); //temp file in memory
$tmp_location = stream_get_meta_data($tmp_file)['uri']; //"location" of temp file

$zip = new ZipArchive;
$res = $zip->open($tmp_location, ZipArchive::CREATE);
$zip->addFile($filepath1, 'file1');
$zip->close();

header('Content-type: application/zip');
header('Content-Disposition: attachment; filename="download.zip"');
echo(file_get_contents($tmp_location));

Answer 5

To create ZIP files on the fly (in memory), you can use ZipFile class from phpMyAdmin:

• PMA\libraries\ZipFile.php

An example of how to use it in your own application:

• https://stackoverflow.com/a/9648562/767871

Note: Your ZIP files will be limited by PHP's memory limit, resulting in corrupted archive if you exceed the limit.

Answer 6

maraspin's Answer is what I tried. Strangely, I got it working by removing the header line that references the file size:

header('Content-Length: ' . filesize($file));

With the above change, the code works like a breeze! Without this change, I used to get the following error message:

End-of-central-directory signature not found. Either this file is not a zipfile, or it constitutes one disk of a multi-part archive. In the latter case the central directory and zipfile comment will be found on the last disk(s) of this archive.

Test environment:

OS: Ubuntu 10.10 Browser: Firefox And the default LAMP stack.

Answer 7

itsols If you want to insert the 'Content-Length' do it like this:

$length = filesize($file);
header('Content-Length: ' . $length);

I don't know why, but it crashes if you put it in the same line.

Answer 8

On Unix systems (and maybe others),

you can apply a simple trick to @maraspin's answer by deleting the file entry for the file ("unlinking" it from its inode), and send its data using a handle opened previously. This is basically the same thing tmpfile() does; this way you can "temporarify" any file.

The code is the same as maraspin's up to the very last lines:

// Prepare File
$file = tempnam("tmp", "zip");
$zip = new ZipArchive();
$zip->open($file, ZipArchive::OVERWRITE);

// Stuff with content
$zip->addFromString('file_name_within_archive.ext', $your_string_data);
$zip->addFile('file_on_server.ext', 'second_file_name_within_archive.ext');

// Close and send to users
$zip->close();

header('Content-Type: application/zip');
header('Content-Length: ' . filesize($file));
header('Content-Disposition: attachment; filename="file.zip"');

// open a handle to the zip file.
$fp = fopen($file, 'rb');
// unlink the file. The handle will stay valid, and the disk space will remain occupied, until the script ends or all file readers have terminated and closed.
unlink($file);
// Pass the file descriptor to the Web server.
fpassthru($fp);

As soon as the script finishes, or terminates abnormally, or the application pool is cycled, or the Apache child gets recycled -- the "disappearance" of the file will be formalized and its disk space released.