Index: includes/file.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/file.inc,v
retrieving revision 1.79
diff -u -F^f -r1.79 file.inc
--- includes/file.inc	5 Jul 2006 11:45:51 -0000	1.79
+++ includes/file.inc	19 Jul 2006 16:01:16 -0000
@@ -14,6 +14,7 @@
 
 define('FILE_DOWNLOADS_PUBLIC', 1);
 define('FILE_DOWNLOADS_PRIVATE', 2);
+define('FILE_DOWNLOADS_CUSTOM', 3);
 define('FILE_CREATE_DIRECTORY', 1);
 define('FILE_MODIFY_PERMISSIONS', 2);
 define('FILE_EXISTS_RENAME', 0);
@@ -35,6 +36,7 @@ function file_create_url($path) {
     case FILE_DOWNLOADS_PUBLIC:
       return $GLOBALS['base_url'] .'/'. file_directory_path() .'/'. str_replace('\\', '/', $path);
     case FILE_DOWNLOADS_PRIVATE:
+    case FILE_DOWNLOADS_CUSTOM:
       return url('system/files/'. $path, NULL, NULL, TRUE);
   }
 }
@@ -551,12 +553,17 @@ function file_transfer($source, $headers
     // To prevent HTTP header injection, we delete new lines that are
     // not followed by a space or a tab.
     // See http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
-    $header = preg_replace('/\r?\n(?!\t| )/', '', $header);
-    header($header);
+    header(preg_replace('/\r?\n(?!\t| )/', '', $header));
   }
 
-  $source = file_create_path($source);
+  $handler = variable_get('file_downloads', FILE_DOWNLOADS_PUBLIC) == FILE_DOWNLOADS_CUSTOM ?
+    variable_get('file_transfer_handler', 'file_transfer_php') : 'file_transfer_php';
+  call_user_func($handler, file_create_path($source));
 
+  exit();
+}
+
+function file_transfer_php($source) {
   // Transfer file in 1024 byte chunks to save memory usage.
   if ($fd = fopen($source, 'rb')) {
     while (!feof($fd)) {
@@ -567,7 +574,11 @@ function file_transfer($source, $headers
   else {
     drupal_not_found();
   }
-  exit();
+}
+
+function file_transfer_xsendfile($source) {
+  // Let the web server do the heavy lifting.
+  header('X-Sendfile: ' . $source);
 }
 
 /**
Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.332
diff -u -F^f -r1.332 system.module
--- modules/system/system.module	10 Jul 2006 21:12:09 -0000	1.332
+++ modules/system/system.module	19 Jul 2006 16:01:20 -0000
@@ -442,7 +442,7 @@ function system_file_system_settings() {
     '#type' => 'radios',
     '#title' => t('Download method'),
     '#default_value' => variable_get('file_downloads', FILE_DOWNLOADS_PUBLIC),
-    '#options' => array(FILE_DOWNLOADS_PUBLIC => t('Public - files are available using http directly.'), FILE_DOWNLOADS_PRIVATE => t('Private - files are transferred by Drupal.')),
+    '#options' => array(FILE_DOWNLOADS_PUBLIC => t('Public - files are available directly using HTTP.'), FILE_DOWNLOADS_PRIVATE => t('Private - after applying access controls, files are transferred by Drupal.'), FILE_DOWNLOADS_CUSTOM => t('Custom - after applying access controls, files are transferred by a user-defined handler.')),
     '#description' => t('If you want any sort of access control on the downloading of files, this needs to be set to <em>private</em>. You can change this at any time, however all download URLs will change and there may be unexpected problems so it is not recommended.')
   );
 
Index: modules/upload/upload.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/upload/upload.module,v
retrieving revision 1.113
diff -u -F^f -r1.113 upload.module
--- modules/upload/upload.module	19 Jul 2006 07:15:35 -0000	1.113
+++ modules/upload/upload.module	19 Jul 2006 16:01:20 -0000
@@ -89,7 +89,7 @@ function upload_menu($may_cache) {
     if (isset($_SESSION['file_previews'])) {
       foreach ($_SESSION['file_previews'] as $fid => $file) {
         $filename = file_create_filename($file->filename, file_create_path());
-        if (variable_get('file_downloads', FILE_DOWNLOADS_PUBLIC) ==  FILE_DOWNLOADS_PRIVATE) {
+        if (variable_get('file_downloads', FILE_DOWNLOADS_PUBLIC) !=  FILE_DOWNLOADS_PUBLIC) {
           // strip file_directory_path() from filename. @see file_create_url
           if (strpos($filename, file_directory_path()) !== FALSE) {
             $filename = trim(substr($filename, strlen(file_directory_path())), '\\/');