How to finish batch and redirect then - redirect

Question

I'm working on a Drupal 7 project. I'm using a batch, implenting some operations, and showing a progress bar. in my "formulaire_finished", wich is executed at the end, as last operation of the batch, I want to download a file, and then redirect to another page, because the process is over.
However, The readfile() function use a drupal_exit(), and so my redirection isn't done.
Here is my code:
function formulaire_finished($success, $results, $operations) {
if ($success) {
$path = $results['infos']['path'];
download_file($path);
// Redirection
drupal_goto($_SESSION['my_page'], array('query' => array('details' => '1')));
} else {
// An error occurred.
// $operations contains the operations that remained unprocessed.
$error_operation = reset($operations);
drupal_set_message(t('An error occurred while processing #operation with arguments : #args', array('#operation' => $error_operation[0], '#args' => print_r($error_operation[0], TRUE), )));
}
}
download function:
function download_file($path) {
$dir = $path;
$filename = basename($dir);
if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE')) {
drupal_add_http_header('Pragma', 'public');
drupal_add_http_header('Cache-Control', 'must-revalidate, post-check=0, pre-check=0');
} else {
drupal_add_http_header('Pragma', 'no-cache');
}
drupal_add_http_header('Expires', '0');
drupal_add_http_header('Content-Type', 'application/vnd.ms-excel');
drupal_add_http_header('Content-Disposition', 'attachment; filename=' . basename($dir) . ';');
drupal_add_http_header('Content-Transfer-Encoding', 'binary');
drupal_add_http_header('Content-Length', filesize($dir));
readfile($dir);
unlink($dir);
drupal_exit();
}
All ideas are welcome.

Answer 1

In the below function , can you try to return true always from the below function.
function download_file($path) {
$dir = $path;
$filename = basename($dir);
if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE')) {
drupal_add_http_header('Pragma', 'public');
drupal_add_http_header('Cache-Control', 'must-revalidate, post-check=0, pre-check=0');
} else {
drupal_add_http_header('Pragma', 'no-cache');
}
drupal_add_http_header('Expires', '0');
drupal_add_http_header('Content-Type', 'application/vnd.ms-excel');
drupal_add_http_header('Content-Disposition', 'attachment; filename=' . basename($dir) . ';');
drupal_add_http_header('Content-Transfer-Encoding', 'binary');
drupal_add_http_header('Content-Length', filesize($dir));
readfile($dir);
unlink($dir);
//drupal_exit();
// Can you use simple return here
return true;
}

Answer 2

I don't think you should output the file for download during the finish callback of a batch operation. You should save the file to drupal's file system and save a reference to the file. You can then download it after the batch finishes.