[newlib-cygwin] Cygwin: FIFO: improve the check for the listen_client thread

[newlib-cygwin] Cygwin: FIFO: improve the check for the listen_client thread

[Ken Brown]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=102571f85da6344591848df2c8ebc200699cb031

commit 102571f85da6344591848df2c8ebc200699cb031
Author: Ken Brown <kbrown@cornell.edu>
Date:   Thu May 9 12:28:21 2019 -0400

    Cygwin: FIFO: improve the check for the listen_client thread
    
    Add a method fhandler_fifo::check_listen_client_thread that checks
    whether the thread is running.  Use it in raw_read instead of just
    testing the handle listen_client_thr.

Diff:
---
 winsup/cygwin/fhandler.h       |  1 +
 winsup/cygwin/fhandler_fifo.cc | 34 ++++++++++++++++++++++++++++++++--
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index f4c0f03..969b23a 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -1274,6 +1274,7 @@ class fhandler_fifo: public fhandler_base
   void delete_client_handler (int);
   bool listen_client ();
   int stop_listen_client ();
+  int check_listen_client_thread ();
   void record_connection (fifo_client_handler&);
 public:
   fhandler_fifo ();
diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index 1b1b3c7..4bf157d 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -744,13 +744,43 @@ retry:
   return eof;
 }
 
+/* Is the lct running? */
+int
+fhandler_fifo::check_listen_client_thread ()
+{
+  int ret = 0;
+
+  if (listen_client_thr)
+    {
+      DWORD waitret = WaitForSingleObject (listen_client_thr, 0);
+      switch (waitret)
+	{
+	case WAIT_OBJECT_0:
+	  CloseHandle (listen_client_thr);
+	  break;
+	case WAIT_TIMEOUT:
+	  ret = 1;
+	  break;
+	default:
+	  debug_printf ("WaitForSingleObject failed, %E");
+	  ret = -1;
+	  __seterrno ();
+	  CloseHandle (listen_client_thr);
+	  break;
+	}
+    }
+  return ret;
+}
+
 void __reg3
 fhandler_fifo::raw_read (void *in_ptr, size_t& len)
 {
   size_t orig_len = len;
 
-  /* Start the listen_client thread if necessary (shouldn't be). */
-  if (!listen_client_thr && !listen_client ())
+  /* Make sure the lct is running. */
+  int res = check_listen_client_thread ();
+  debug_printf ("lct status %d", res);
+  if (res < 0 || (res == 0 && !listen_client ()))
     goto errout;
 
   while (1)