Adding Content-Length header

Adding a Content-Length header for ZipStream can be achieved by using the options SIMULATION_STRICT or SIMULATION_LAX in the operationMode parameter.

In the SIMULATION_STRICT mode, ZipStream will not allow to calculate the size based on reading the whole file. SIMULATION_LAX will read the whole file if necessary.

SIMULATION_STRICT is therefore useful to make sure that the size can be calculated efficiently.

use ZipStream\OperationMode;
use ZipStream\ZipStream;

$zip = new ZipStream(
    operationMode: OperationMode::SIMULATE_STRICT, // or SIMULATE_LAX
    defaultEnableZeroHeader: false,
    sendHttpHeaders: true,
    outputStream: $stream,
);

// Normally add files
$zip->addFile('sample.txt', 'Sample String Data');

// Use addFileFromCallback and exactSize if you want to defer opening of
// the file resource
$zip->addFileFromCallback(
    'sample.txt',
    exactSize: 18,
    callback: function () {
        return fopen('...');
    }
);

// Read resulting file size
$size = $zip->finish();

// Tell it to the browser
header('Content-Length: '. $size);

// Execute the Simulation and stream the actual zip to the client
$zip->executeSimulation();