Source of upload.php

<!DOCTYPE HTML>
<html lang="en-US">
<head>
    <meta charset="UTF-8">
    <title>upload.php</title>
</head>
<body>
    
<?php
$fileName = $_FILES['uploadedFile']['name'];
$tmpName = $_FILES['uploadedFile']['tmp_name'];
$size = $_FILES['uploadedFile']['size'];

print "Trying to upload $fileName <br />";
if (preg_match("/txt$/", $fileName)){
  if ($size < 100000){
    $result = move_uploaded_file($tmpName, "uploaded.txt");
    if ($result){
      print "File successfully uploaded!";
    }
  } else {
    print "must be < 100K";
  } // end if
} else {
  print "only text files allowed";
} // end if

?>
    
</body>
</html>