session.upload_progress.enabled = on
session.upload_progress.prefix = "upload_progress_"
session.upload_progress.name = "blabla"

<form action="upload.php" method="POST" enctype="multipart/form-data">
 <input type="hidden" name="<?php echo ini_get("session.upload_progress.name"); ?>" value="blabla" />
 <input type="file" name="file1" />
 <input type="file" name="file2" />
 <input type="submit" />
</form>

<?php
$_SESSION["upload_progress_blabla"] = array(
 "start_time" => 1234567890,   // The request time
 "content_length" => 57343257, // POST content length
 "bytes_processed" => 453489,  // Amount of bytes received and processed
 "done" => false,              // true when the POST handler has finished, successfully or not
 "files" => array(