The following code list all files in a folder and allows the user to download one of them. It is working but I think it could be done better.

Is there a way to reduce the number of forms to only one and to improve the way I retrieve the name of the file to download?

My second concern is about the security of my getFile function.

function listDir($directoryName)
    $directory = opendir($directoryName);
    $files = array();
    while ($elem = readdir($directory))
        if ($elem != '.' && $elem != '..' && $elem != '.htaccess')
            $files[] = $elem;
    if (!empty($directory))
        echo "<ul>";
        foreach ($files as $file)
            $filePath = $directoryName.'/'.$file;
            echo "<form method='post' action=".htmlentities($_SERVER['PHP_SELF']).">";
            echo "<li>($fileDate)";
            echo "<input type='hidden' name='$file' value='$filePath'>";
            echo " <button type='submit' name='getFile'>Télécharger</button> ";
            echo "$file</li>";
            echo "</form>";
        echo "</ul>";

function getFile($file)
    if (file_exists($file))
        header('Content-Description: File Transfer');
        header('Content-Type: application/octet-stream');
        header('Content-Disposition: attachment; filename='.basename($file));
        header('Expires: 0');
        header('Cache-Control: must-revalidate');
        header('Pragma: public');
        header('Content-Length: ' . filesize($file));

if (isset($_POST['getFile']))
    $keys = array_keys($_POST);
    $file = $_POST[$keys[0]];

  • \$\begingroup\$ Your getFile function is incredibly insecure. The number one rule is to never trust the user. I could POST getFile=/var/etc/passwd or getFile=../my/secret/file or something. \$\endgroup\$
    – Schism
    Jul 8 '14 at 5:06

Let's post a dry review first, before jumping in to the conceptual stuff:

  • You are allowing your end-users download any file on the server. All I need to do is to change the path to /etc/passwd on any form and submit, and I get your server's password file! And if I don't have permissions to that, no biggy, I can still download all of your owned files on the server.
  • Invalid HTML markup - <form> isn't allowed directly inside of <ul>. Only <li> is.
  • Separate logic and presentation - You shouldn't mix the part where the user sees your form, and the part where he downloads the file.

A better approach?

A better approach would be a PHP file which is capable of serving files. That PHP file needs to make sure that the file being requested is found in a very specific list of allowed directories (i.e. I allow from images/ and from static/ but not from anywhere else.

Then, when you download a file, all you need to do is to link (With an <a>) to


And have the PHP file_server handle the serving of the requested file.

Getting Fancy

You can even use .htaccess and mod_rewrite to rewrite URLs like this:




Making the fact that PHP is the one sending the file completely transparent to the user!

  • \$\begingroup\$ Taking into account your advice, I replaced my getFile with this script (improved with $finfo = new finfo; $ctype = $finfo->file($file, FILEINFO_MIME_TYPE); for the MIME) \$\endgroup\$
    – lbeziaud
    Jul 8 '14 at 12:50

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