递归读取文件和文件夹，并使用PHP创建它们的超链接

Question

我的目录中有以下文件结构。

file.txt
file2.txt
  folder1
    file1.txt
  folder2
    file1.txt
    file2.txt

对于读取文件和文件夹，我使用此脚本

function read_dir($dir, $mark = '-') {
    $d = opendir($dir);
    while ($name = readdir($d)) {       
        if ($name == '.' || $name == '..') {
            continue;
        }
        elseif (is_dir($name)) {
            echo $mark.'<div class="folder"><b>'.$name.'</b></div>';
            read_dir($name);                
        }
        else
            echo $name.'<br />';
    }
}

read_dir('/path/to/myfolder/.');

我得到了HTML

file.txt<br />
file2.txt<br />-
    <div class="folder"><b>folder1</b></div>
    file1.txt<br />-
    <div class="folder"><b>folder2</b></div>
    file1.txt<br />
file2.txt<br />

我需要设置下载文件的链接，比如

<a href="path/to/myfolder/file.txt">file.txt</a><br />
<a href="path/to/myfolder/file2.txt">file2.txt</a><br />-
<div class="folder"><b>folder1</b></div>
<a href="path/to/myfolder/folder1/file1.txt">file1.txt</a><br />-
<div class="folder"><b>folder2</b></div>
<a href="path/to/myfolder/folder1/file1.txt">file1.txt</a><br />
<a href="path/to/myfolder/folder1/file2.txt">file2.txt</a><br />

如何更改要下载的文件的设置链接的脚本？