* fhandler.h (dirent_states): Add dirent_isroot, dirent_saw_cygdrive,

dirent_saw_dev.
* dir.cc (opendir): Don't zero __flags here.  Push that responsibility to
opendir methods.
(seekdir): Preserve dirent_isrrot in __flags.
(rewinddir): Ditto.
* fhandler_disk_file.cc (fhandler_disk_file::opendir): Set dirent_isroot
appropriately.
(fhandler_disk_file::readdir): Fill in "cygdrive" and "dev" if it is the root
dir and they are missing.
* fhandler_process.cc (fhandler_process::opendir): Set __flags here.
* fhandler_virtual.cc (fhandler_virtual::opendir): Set __flags here.

winsup/cygwin/fhandler_process.cc

@@ -200,8 +200,12 @@ DIR *
 fhandler_process::opendir ()
 {
   DIR *dir = fhandler_virtual::opendir ();
-  if (dir && fileid == PROCESS_FD)
-    fill_filebuf ();
+  if (dir)
+    {
+      if (fileid == PROCESS_FD)
+	fill_filebuf ();
+      dir->__flags = 0;
+    }
   return dir;
 }