Description:
------------
---
From manual page: http://www.php.net/function.move-uploaded-file
---

Example #1 (which is intended to be a _good_ example) demonstrates a filesystem traversal attack by allowing the $destination filename to be determined by user input:

<?php
        $name = $_FILES["pictures"]["name"][$key];
        move_uploaded_file($tmp_name, "$uploads_dir/$name");
?>

Examples in the manual should demonstrate best practices, especially where security is involved.  

Suggest changing the example to include validation for the $destination path, e.g., 
<?php
$uploads_dir = '/uploads';
foreach ($_FILES["pictures"]["error"] as $key => $error) {
    if ($error == UPLOAD_ERR_OK) {
        $tmp_name = $_FILES["pictures"]["tmp_name"][$key];
        $name = $_FILES["pictures"]["name"][$key];

        // $name comes from user input, so we MUST NOT trust that it is safe or correct.
        // realpath() will fail if the destination directory does not exist,
        // and then we check that the destination directory *is* the uploads directory, as intended.
        $destination = "{$uploads_dir}/{$name}";
        $dest_dir = realpath(dirname($destination));
        if ($dest_dir !== $uploads_dir) {
            trigger_error('Bad file name!', E_USER_WARNING);
        } else {
            move_uploaded_file($tmp_name, $destination);
        }
    }
}
?>

Alternatively, the example could not use the user-provided filename at all; generating a hash or random string as the $destination filename.

Also suggest adding a "Warning" box explaining the risks involved in allowing a user to choose where to save files on your filesystem.

Test script:
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n/a

Expected result:
----------------
n/a

Actual result:
--------------
n/a