[newlib-cygwin] Cygwin: pipes: always terminate async IO in blocking mode

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=4003e3dfa1b9bfee12d686f016353a1e20b51e74

commit 4003e3dfa1b9bfee12d686f016353a1e20b51e74
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Tue Sep 7 10:50:47 2021 +0200

    Cygwin: pipes: always terminate async IO in blocking mode
    
    In blocking mode, the underlying IO must always be terminated,
    one way or the other, to make sure the application knows the exact
    state after returning from the IO function.  Therefore, always call
    CancelIo in blocking mode.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/fhandler_pipe.cc | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc
index 76ce895e2..8041a5d51 100644
--- a/winsup/cygwin/fhandler_pipe.cc
+++ b/winsup/cygwin/fhandler_pipe.cc
@@ -293,6 +293,14 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
       if (evt && status == STATUS_PENDING)
 	{
 	  waitret = cygwait (evt, INFINITE, cw_cancel | cw_sig);
+	  /* If io.Status is STATUS_CANCELLED after CancelIo, IO has actually
+	     been cancelled and io.Information contains the number of bytes
+	     processed so far.
+	     Otherwise IO has been finished regulary and io.Status contains
+	     valid success or error information. */
+	  CancelIo (get_handle ());
+	  if (waitret == WAIT_SIGNALED && io.Status != STATUS_CANCELLED)
+	    waitret = WAIT_OBJECT_0;
 	  if (waitret == WAIT_OBJECT_0)
 	    status = io.Status;
 	}
@@ -302,7 +310,11 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
 	  break;
 	}
       else if (waitret == WAIT_SIGNALED)
-	status = STATUS_THREAD_SIGNALED;
+	{
+	  status = STATUS_THREAD_SIGNALED;
+	  nbytes += io.Information;
+	  break;
+	}
       else if (isclosed ())  /* A signal handler might have closed the fd. */
 	{
 	  if (waitret == WAIT_OBJECT_0)
@@ -363,10 +375,7 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
       nbytes = (size_t) -1;
     }
   else if (status == STATUS_THREAD_CANCELED)
-    {
-      CancelIo (get_handle ());
-      pthread::static_cancel_self ();
-    }
+    pthread::static_cancel_self ();
   len = nbytes;
 }
 
@@ -443,6 +452,14 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
       if (evt && status == STATUS_PENDING)
 	{
 	  waitret = cygwait (evt, INFINITE, cw_cancel | cw_sig);
+	  /* If io.Status is STATUS_CANCELLED after CancelIo, IO has actually
+	     been cancelled and io.Information contains the number of bytes
+	     processed so far.
+	     Otherwise IO has been finished regulary and io.Status contains
+	     valid success or error information. */
+	  CancelIo (get_handle ());
+	  if (waitret == WAIT_SIGNALED && io.Status != STATUS_CANCELLED)
+	    waitret = WAIT_OBJECT_0;
 	  if (waitret == WAIT_OBJECT_0)
 	    status = io.Status;
 	}
@@ -452,7 +469,11 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
 	  break;
 	}
       else if (waitret == WAIT_SIGNALED)
-	status = STATUS_THREAD_SIGNALED;
+	{
+	  status = STATUS_THREAD_SIGNALED;
+	  nbytes += io.Information;
+	  break;
+	}
       else if (isclosed ())  /* A signal handler might have closed the fd. */
 	{
 	  if (waitret == WAIT_OBJECT_0)
@@ -485,10 +506,7 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
   if (status == STATUS_THREAD_SIGNALED && nbytes == 0)
     set_errno (EINTR);
   else if (status == STATUS_THREAD_CANCELED)
-    {
-      CancelIo (get_handle ());
-      pthread::static_cancel_self ();
-    }
+    pthread::static_cancel_self ();
   return nbytes ?: -1;
 }