[newlib-cygwin] Cygwin: pipe: Fix notification timing of select_sem.

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=08b8534d0a0fc65b800433f88c278a18de70d842

commit 08b8534d0a0fc65b800433f88c278a18de70d842
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Thu Sep 9 12:08:39 2021 +0900

    Cygwin: pipe: Fix notification timing of select_sem.
    
    - Make select_sem notify even when read/write partially.

Diff:
---
 winsup/cygwin/fhandler_pipe.cc | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc
index ea8ea41dd..488e14be8 100644
--- a/winsup/cygwin/fhandler_pipe.cc
+++ b/winsup/cygwin/fhandler_pipe.cc
@@ -311,6 +311,9 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
 	    {
 	      status = STATUS_THREAD_SIGNALED;
 	      nbytes += io.Information;
+	      if (select_sem && io.Information > 0)
+		ReleaseSemaphore (select_sem,
+				  get_obj_handle_count (select_sem), NULL);
 	      break;
 	    }
 	  status = io.Status;
@@ -365,6 +368,8 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
 
       if (nbytes_now == 0)
 	break;
+      else if (select_sem)
+	ReleaseSemaphore (select_sem, get_obj_handle_count (select_sem), NULL);
     }
   ReleaseMutex (read_mtx);
   if (evt)
@@ -376,8 +381,6 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
     }
   else if (status == STATUS_THREAD_CANCELED)
     pthread::static_cancel_self ();
-  if (select_sem && nbytes)
-    ReleaseSemaphore (select_sem, get_obj_handle_count (select_sem), NULL);
   len = nbytes;
 }
 
@@ -472,6 +475,9 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
 	    {
 	      status = STATUS_THREAD_SIGNALED;
 	      nbytes += io.Information;
+	      if (select_sem && io.Information > 0)
+		ReleaseSemaphore (select_sem,
+				  get_obj_handle_count (select_sem), NULL);
 	      break;
 	    }
 	  status = io.Status;
@@ -502,6 +508,8 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
 
       if (nbytes_now == 0)
 	break;
+      else if (select_sem)
+	ReleaseSemaphore (select_sem, get_obj_handle_count (select_sem), NULL);
     }
   if (evt)
     CloseHandle (evt);
@@ -509,8 +517,6 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
     set_errno (EINTR);
   else if (status == STATUS_THREAD_CANCELED)
     pthread::static_cancel_self ();
-  if (select_sem && nbytes)
-    ReleaseSemaphore (select_sem, get_obj_handle_count (select_sem), NULL);
   return nbytes ?: -1;
 }