Problem med upload bibliotek.

Vha. af scriptet herunder uploader jeg et billede, og laver automatisk en thumb. Scriptet virker som det er nu, men med et enkelt problem.

$updir defineres og angiver hvilket bibliotek billedet skal uploades til, hvilket virker fint.
Men når jeg skal lave min thumbnail, så er jeg nødt til at angive hvor det originale billede befinder sig. Det ville jo være dejligt, at det automatisk fulgtes med upload biblioteket.

///////// SCRIPT START ////////////////
<?php
$updir = $_SERVER["DOCUMENT_ROOT"]."/test/upload";  // Definer stien til dit oploadbibliotek
echo $updir." :updir<br />";
$aft = array('image/jpeg','image/pjpeg','image/png'); // De filtyper der kan uploades

/*
    Function checkgd()
    checks the version of gd, and returns "yes" when it's higher than 2
*/
function checkgd(){
    $gd2="";
    ob_start();
    phpinfo(8);
    $phpinfo=ob_get_contents();
    ob_end_clean();
    $phpinfo=strip_tags($phpinfo);
    $phpinfo=stristr($phpinfo,"gd version");
    $phpinfo=stristr($phpinfo,"version");
    preg_match('/\d/',$phpinfo,$gd);
    if ($gd[0]=='2'){$gd2="yes";}
    return $gd2;
}

/*
    Function ditchtn($arr,$thumbname)
    filters out thumbnails
*/
function ditchtn($arr,$thumbname){
    foreach ($arr as $item){
        if (!preg_match("/^".$thumbname."/",$item)){$tmparr[]=$item;}
    }
    return $tmparr;
}

/*
    Function createthumb($name,$filename,$new_w,$new_h)
    creates a resized image
    variables:
    $name        Original filename
    $filename    Filename of the resized image
    $new_w        width of resized image
    $new_h        height of resized image
*/   
function createthumb($name,$filename,$new_w,$new_h){
    global $gd2;
    $system=explode(".",$name);

    echo $system[1]." :system[1]<br />";
    echo $name." :name<br />";

    if (preg_match("/jpg|jpeg/",$system[1])){$src_img=imagecreatefromjpeg("upload/".$name);}
    if (preg_match("/png/",$system[1])){$src_img=imagecreatefrompng("upload/".$name);}
    $old_x=imageSX($src_img);
    $old_y=imageSY($src_img);
    if ($old_x > $old_y) {
        $thumb_w=$new_w;
        $thumb_h=$old_y*($new_h/$old_x);
    }
    if ($old_x < $old_y) {
        $thumb_w=$old_x*($new_w/$old_y);
        $thumb_h=$new_h;
    }
    if ($old_x == $old_y) {
        $thumb_w=$new_w;
        $thumb_h=$new_h;
    }
    if ($gd2==""){
        $dst_img=ImageCreate($thumb_w,$thumb_h);
        imagecopyresized($dst_img,$src_img,0,0,0,0,$thumb_w,$thumb_h,$old_x,$old_y);
    }else{
        $dst_img=ImageCreateTrueColor($thumb_w,$thumb_h);
        imagecopyresampled($dst_img,$src_img,0,0,0,0,$thumb_w,$thumb_h,$old_x,$old_y);
    }
    if (preg_match("/png/",$system[1])){
        imagepng($dst_img,$filename);
    } else {
        imagejpeg($dst_img,$filename);
    }
    imagedestroy($dst_img);
    imagedestroy($src_img);
}

/*
        Function directory($directory,$filters)
        reads the content of $directory, takes the files that apply to $filter
        and returns an array of the filenames.
        You can specify which files to read, for example
        $files = directory(".","jpg,gif");
                gets all jpg and gif files in this directory.
        $files = directory(".","all");
                gets all files.
*/
function directory($dir,$filters){
    $handle=opendir($dir);
    $files=array();
    if ($filters == "all"){while(($file = readdir($handle))!==false){$files[] = $file;}}
    if ($filters != "all"){
        $filters=explode(",",$filters);
        while (($file = readdir($handle))!==false) {
            for ($f=0;$f<sizeof($filters);$f++):
                $system=explode(".",$file);
                if ($system[1] == $filters[$f]){$files[] = $file;}
            endfor;
        }
    }
    closedir($handle);
    return $files;
}

?>
<html>
<head>
<title>Untitled Document</title>
<link href="scroll.css" type="text/css" rel="stylesheet">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>

<body bgcolor="#D0D0D0" text="#000000">
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">upload</font>
<br><br>
<?php

if (isset($_GET['mode']) && $_GET['mode'] == "upload") {
  $newfilename = $updir."/".$_FILES['fil']['name'];

    if (empty($_REQUEST['fil'])) {
        echo "Du skal vælge en fil";
    }
    else {

      if (in_array($_FILES['fil']['type'],$aft)) {
      if (move_uploaded_file($_FILES['fil']['tmp_name'], $newfilename)) {
        $gd2=checkgd();
        createthumb($_FILES['fil']['name'],$updir."/"."thumb_".$_FILES['fil']['name'],100,100);

        $imginfo = getimagesize($newfilename);
        $imgwidth = $imginfo[0];  //bredde i pixels
        $imgheight = $imginfo[1]; //højde i pixels
        $imgtype = $imginfo[2];  //jpg, gif, bmp osv
        $imghtml = $imginfo[3];  //height="yyy" width="xxx" - for use directly in html
            Echo "Alt OK<br />";
            Echo $_REQUEST['tekst'];
            }
            else {}
        }
        else {
              echo "Filtypen er ikke korrekt!";
        }   
    }

}

elseif (empty($_GET['mode'])) {
    ?>

    <form action="test2.php?mode=upload" method="post" enctype="multipart/form-data">
    <input type="hidden" name="MAX_FILE_SIZE" value="100000">
    <input type="file" name="fil"><br />
    <input type="text" name="tekst">
    <br /><br />
    <input type="submit" name="submit" value="Upload" >
    </form>

    <?php

}
else {
    echo "Bad guy!";
}
?>

</body>
</html>
///////////////// SCRIPT SLUT/////////////////