Index: modules/upload.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/Attic/upload.module,v
retrieving revision 1.100.2.12
diff -u -Ftion -r1.100.2.12 upload.module
--- modules/upload.module	1 Jan 2007 18:10:05 -0000	1.100.2.12
+++ modules/upload.module	5 Jan 2007 11:07:12 -0000
@@ -189,6 +189,19 @@ function upload_file_download($file) {
       $node = node_load($file->nid);
       if (node_access('view', $node)) {
         $name = mime_header_encode($file->filename);
+        // Mime filename should be double quoted to handle filenames with spaces.
+        if (preg_match('/[^\x20-\x7E]/', $file->filename)) { 
+          // non-ascii --> needs encoding.
+          $name = mime_header_encode($file->filename);
+        }
+        else if (preg_match('/[ \(\)\<\>\@\,\;\:\\\"\/\[\]\?\=]/', $file->filename)) {
+          // n tokens, tspecials characters, SHOULD be 'quoted-string'.
+          $name = '"'. $file->filename .'"';
+        }
+        else {
+          // only ascii, one token, no tspecials.
+          $name = $file->filename;
+        }
         $type = mime_header_encode($file->filemime);
         return array(
           'Content-Type: '. $type .'; name='. $name,