* dtable.cc (dtable::find_fifo): Release lock after fifo found (still racy).

* fhandler.h (fhandler_fifo::get_io_handle): New fifo-specific method.
* fhandler_fifo.cc (fhandler_fifo::close): Close output_handle only if it is
open.
(fhandler_fifo::open_not_mine): Reorganize slightly.  Don't call _pinfo methods
when the fifo is owned by me or suffer dtable lock_cs deadlock.
(fhandler_fifo::open): Call open_not_mine first, otherwise open myself
(racy).
* pinfo.cc (_pinfo::commune_recv): Duplicate fifo handles here in requesting
processes arena to avoid one potential race (of many).
(_pinfo::commune_send): Move all PICOM_FIFO code under one case statement.
* thread.cc (pthread::init_mainthread) Use existing hMainProc handle rather
than calling GetCurrentProcess.

winsup/cygwin/dtable.cc

@@ -557,13 +557,18 @@ fhandler_fifo *
 dtable::find_fifo (const char *path)
 {
   lock ();
+  fhandler_fifo *fh_res = NULL;
   for (unsigned i = 0; i < size; i++)
     {
       fhandler_base *fh = fds[i];
       if (fh && fh->isfifo () && strcmp (path, fh->get_win32_name ()) == 0)
-	return (fhandler_fifo *) fh;
+	{
+	  fh_res = (fhandler_fifo *) fh;
+	  break;
+	}
     }
-  return NULL;
+  unlock ();
+  return fh_res;
 }
 
 select_record *