--- a/index.php	Tue Oct 21 18:01:43 2014 +0900
+++ b/index.php	Tue Oct 21 21:31:38 2014 +0900
@@ -1,54 +1,65 @@
 <?php
-  //real men use UTC for internets
+  // Required for strftime(). Set to UTC because :internet:.
   date_default_timezone_set('UTC');
-  $wwwroot = $_ENV["DOCUMENT_ROOT"];
-  $link_prefix = "/";
-  $link_base = rtrim(preg_replace("#/+#", "/", urldecode($_ENV["REQUEST_URI"])),'/');
-  $link_path = substr($link_base,strlen(utf8_decode($link_prefix)));
-  $path = realpath("$wwwroot/".$link_path);
-  if (!$path) { die("fail"); }
-  $dir_handle = @opendir($path);
-  $to_dir = explode('/', trim($link_path,'/'));
-  array_unshift($to_dir, trim($link_prefix,'/'));
+
+  // $path: actual requested path, with $alias_prefix removed, relative to $root.
+  $path = $_SERVER["REQUEST_URI"];
+  $query_string_start = strpos($path, "?");
+  if ($query_string_start !== false) {
+    $path = substr($path, 0, $query_string_start);
+  }
+  $path = urldecode($path);
+
+  $prefix = $_SERVER["DL_PREFIX"];
+
+  $path = substr($path, strlen(utf8_decode($prefix)));
+  if ($path === false) { $path = "/"; }
+
+  // root of directory listing.
+  $root = $_SERVER["DL_ROOT"];
+  if ($root === "") { $root = $_SERVER["DOCUMENT_ROOT"]; }
+
+  // current directory being listed.
+  $current_dir = $root . $path;
+
+  if (realpath($root . $path) === false) {
+    header("HTTP/1.0 404 Not Found");
+  } elseif (substr($current_dir, -1) !== "/") {
+    header("Location: " . $path . "/", false, 301);
+  }
+
+  if (http_response_code() !== 200) { exit; }
+
+  // $link_prefix = "/";
+  // $link_base = rtrim(preg_replace("#/+#", "/", urldecode($_ENV["REQUEST_URI"])),'/');
+  // $link_path = substr($link_base,strlen(utf8_decode($link_prefix)));
+  // $path = realpath("$wwwroot/".$link_path);
+  // if (!$path) { die("fail"); }
+
+  $dir_handle = @opendir($root . $path);
   $files = array();
   $dirs = array();
-  while ($file = readdir($dir_handle)) {
-    if ($file == '.' or $file == '..') { continue; }
-    elseif (is_dir("$path/$file")) { $dirs[] = $file; }
+  while (($file = readdir($dir_handle)) !== false) {
+    if ($file === "." or $file === "..") { continue; }
+    elseif (is_dir($root . $path . $file)) { $dirs[] = $file; }
     else { $files[] = $file; }
   }
   sort($files);
   sort($dirs);
-  function h($string) { return htmlspecialchars($string, ENT_QUOTES, 'UTF-8'); }
+
+  // BEGIN UTILITY
+  function h($string) { return htmlspecialchars($string, ENT_QUOTES, "UTF-8"); }
   function a($string) { return preg_replace("#(%2F)+#", "/", rawurlencode($string)); }
-  function link_to($target, $title) {
-    return("<a href=\"".a($target)."\">".h($title)."</a>");
-  }
-  function path_tree_header() {
-    global $link_prefix, $link_base, $to_dir;
-    $path_tree = link_to('/', '[root]') . "/";
-    foreach ($to_dir as $level => $dir) {
-      if($dir) {
-        $link = "/";
-        for ($i = 0; $i <= $level; $i++) { $link .= "$to_dir[$i]/"; }
-        $path_tree .= link_to($link, $dir)."/";
-      }
-    }
-    return "Index of $path_tree";
-  }
-  function title() {
-    global $link_base;
-    return "Index of ".h(rtrim($link_base,"/")."/");
-  }
+  function link_to($target, $title) { return('<a href="' . a($target) . '">' . h($title) . "</a>"); }
 
-  function nice_size($size) {
-    $thousand_units = array('ko', 'Mo', 'Go', 'To', 'Po');
+  function human_size($size) {
+    $thousand_units = array("ko", "Mo", "Go", "To", "Po");
 
     $return_format = "%d %s";
 
     if ($size <= 1) {
       $return_unit = "octet";
-    } elseif ($size < 10000) {
+    } elseif ($size < 1000) {
       $return_unit = "octets";
     } else {
       $size /= 1000;
@@ -58,27 +69,49 @@
     }
     return sprintf($return_format, $size, $return_unit);
   }
+  // END UTILITY
+
+  function tree_link() {
+    global $path, $prefix;
+
+    $path_array = explode("/", trim($path, "/"));
+    array_unshift($path_array, trim($prefix, "/"));
+
+    $tree_path = "/";
+    $tree_link = link_to($tree_path, "[root]") . "/";
+
+    foreach ($path_array as $p) {
+      if ($p === "") { continue; }
+      $tree_path .= $p . "/";
+      $tree_link .= link_to($tree_path, $p) . "/";
+    }
+
+    return $tree_link;
+  }
 
   function file_rows($files, $is_dir) {
-    global $path, $link_base, $link_prefix;
+    global $path, $root, $prefix;
 
     $file_rows = "";
+    $file_suffix = "";
+
     if ($is_dir) {
       $file_suffix = "/";
-      if($link_base != $link_prefix) {
-        $file_rows .= "<tr><td colspan=3>".link_to(dirname($link_base)."/","..")."</td></tr>";
+
+      if ($path !== "/") {
+        $file_rows .= "<tr><td colspan=3>" . link_to(dirname($prefix . $path) . "/", "..") . "</td></tr>";
       }
-    } else { $file_suffix = ""; }
+    }
 
     foreach($files as $file) {
-      $file_stat = stat("$path/".$file);
+      $file_stat = stat($root . $path . "/". $file);
 
       $file_rows .= "<tr>";
-      $file_rows .= "<td>".link_to("$link_base/".$file.$file_suffix, $file.$file_suffix)."</td>";
+      $file_rows .= "<td>".link_to($file . $file_suffix, $file . $file_suffix)."</td>";
 
       $file_rows .= "<td>";
       if ($is_dir) { $file_rows .= "[dir]"; }
-      else { $file_rows .= nice_size($file_stat['size']); }
+      else { $file_rows .= human_size($file_stat['size']); }
       $file_rows .= "</td>";
 
       $file_rows .= "<td>".h(strftime("%Y-%m-%d %H:%M %Z", $file_stat['mtime']))."</td>";
@@ -92,7 +125,7 @@
 <!doctype html>
 <head>
   <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
-  <title><?php echo title(); ?></title>
+  <title>Index of <?php echo h($prefix . $path); ?></title>
   <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">
   <style type="text/css">
     * { box-sizing: border-box; }
@@ -147,7 +180,7 @@
   </style>
 </head>
 <body>
-  <h1><?php echo path_tree_header(); ?></h1>
+  <h1>Index of <?php echo tree_link(); ?></h1>
 
   <table>
     <thead><tr>
@@ -160,4 +193,11 @@
       <?php echo file_rows($files, false); ?>
     </tbody>
   </table>
+
+  <footer>
+    <hr>
+    <em>
+      Running <a href="https://bitbucket.org/edogawaconan/dirlist-php">dirlist-php</a>.
+      Powered by PHP <?php echo phpversion(); ?>.
+    </em>
 </body>