Posted by petersprc on 10/04/06 02:18

Hi,

You can use command-line zip to do this. For example, to zip a file to
stdout in unix:

zip - file.txt

Here's a function to zip and stream a file on the fly in PHP using the
zip command:

<?

// This function will zip and transmit a file on the
// fly using the zip command.
//
// Usage example:
//
// zipfly('/tmp/data.txt');

function zipfly($path)
{
// Try to disable the browser cache

header('Pragma: public');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Cache-Control: private', false);

// Run the zip command

$zipErrorFile = tempnam('/tmp', 'zipfly-');

$cmd = 'zip - ' . escapeshellarg($path) .
' 2> ' . escapeshellarg($zipErrorFile);

$proc = popen($cmd, 'r') or die();

// Stream the zip data

if (is_resource($proc) && !feof($proc)) {
if (($data = fread($proc, 8192)) !== false && $data !== '') {
header('Content-Transfer-Encoding: binary');
header('Content-Type: application/zip');
$fileName = preg_replace('/\..*?$/', '', basename($path)) .
'.zip';
header('Content-Disposition: attachment; filename="' .
"$fileName\";");
echo $data;
if (!feof($proc)) {
fpassthru($proc);
}
}
}

// Get the exit code of the command

$exitCode = pclose($proc);

if ($exitCode != 0) {
$msg = "Command \"$cmd\" failed with exit code $exitCode";
$errors = is_file($zipErrorFile) ? file_get_contents($zipErrorFile)
: false;
$msg .= $errors !== false ? ": $errors" : '.';
trigger_error($msg);
}
}

?>

Best Regards,

John Peters

Arkady Renko wrote:
> Gday Guys
>
> I'm attempting to create zip files on the fly for some highly
> compressible, yet very large files stored on my Web server. At present
> I'm using a class from the Zend library by Eric Mueller which I've
> modified to suit my purposes. The problem occurs when I have files of
> an arbitrarily large size.. say > 100mb, whereby I end up with high
> memory usage. At the moment I'm using a workaround whereby the scripts
> may use a very large amount of memory and work on no time limit but
> obviously this is something that must not be done in a production
> environment.
>
> What I'm hoping is that someone has written a class, or solved this by
> 'streaming' a zip file as it's being created to the user to avoid high
> memory usage during the process. My understanding is that using the
> deflate algorithm, you can create sequential 'blocks' of compressed data
> which I imagine would play directly into the hands of what I'd want to
> achieve
>
> Time is not an issue for my clients, as the 2 minutes they may have to
> wait for the script to execute are far better than the extra 200mb they
> would have to download for an uncompressed file. (Example, reduction
> from 420mb to 78mb), however I would like to be able to handle several
> of these operations occurring at once.
>
> Failing that.. looks like I'll have to write something to suit my needs.
> --
> --------------------
> Arkady Renko
> Network Admin
> To email me directly
> Remove all capitals
> and underscores from
> my posting address

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