How do I assign a chmod value of 0777 at the point it the file is uploaded (PHP)?

Question

My system features a conversation area which writes to and draws from a .txt file. I am obviously able to set the permissions through my FTP client but I'm looking to apply the writable functionailty to all files that are uploaded through my system within the PHP. I'll add that security is not an issue.

    <?php

$adminID = $_GET['adminID'];

$name = stripslashes(trim($_POST['name']));
$area = stripslashes(trim($_POST['area']));

mysql_query("INSERT INTO chat_rooms (id, name, area, adminID) VALUES ('', '$name', '$area', '$adminID')");

$image = ($_FILES['image_url']['name']);
$empty = '';


if ($image == $empty)

{
    echo 'NO IMAGE';


}else
{

 $target = "room/test/"; 
 $target = $target .basename($_FILES['image_url']['name']); 
 $target2 = basename($_FILES['image_url']['name']); 



 $image_url = ($_FILES['image_url']['name']);
 $adminarea = 'admin-index.php'; 


mysql_query("UPDATE chat_rooms set file='$image_url' WHERE name = '$name'");



 if(move_uploaded_file($_FILES['image_url']['tmp_name'], $target))
 {

 echo "";
 echo "Your room has been created using the file " . basename( $_FILES['image_url']['name']) ." <br /> <br /> Click <a href=".$adminarea."> here </a> to return to the admin area"; 
 } 
 else { 

 echo "Sorry, there was a problem uploading your file."; 
 } 


}
?>

I apologise for the layout and general syntax of my code