[newlib-cygwin] Cygwin: FIFO: remove incorrect duplexer code

[Ken Brown]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=1372021a2dc380946f9d8b549315975205132413

commit 1372021a2dc380946f9d8b549315975205132413
Author: Ken Brown <kbrown@cornell.edu>
Date:   Thu May 9 10:47:47 2019 -0400

    Cygwin: FIFO: remove incorrect duplexer code
    
    raw_read had some code that was based on an incorrect implementation
    of duplexers.

Diff:
---
 winsup/cygwin/fhandler_fifo.cc | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index a1e395b..dd59eb6 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -780,21 +780,14 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
 		fifo_client_unlock ();
 		return;
 	      }
-	    /* If the pipe is empty, we usually get nread == -1 with
-	       ERROR_NO_DATA or ERROR_PIPE_LISTENING.  An exception is
-	       that in the duplex case we may get nread == 0 when we
-	       attempt to read from the duplex pipe (fc_handler[0]). */
-	    else if (nread < 0)
-	      switch (GetLastError ())
-		{
-		case ERROR_NO_DATA:
-		case ERROR_PIPE_LISTENING:
-		  break;
-		default:
-		  fifo_client_unlock ();
-		  goto errout;
-		}
-	    else if (nread == 0 && (!duplexer || i > 0))
+	    /* If the pipe is empty, we  get nread == -1 with
+	       ERROR_NO_DATA. */
+	    else if (nread < 0 && GetLastError () != ERROR_NO_DATA)
+	      {
+		fifo_client_unlock ();
+		goto errout;
+	      }
+	    else if (nread == 0)
 	      /* Client has disconnected. */
 	      {
 		fc_handler[i].state = fc_invalid;