[PATCH] Cygwin: pipe: Handle STATUS_PENDING even for nonblocking mode.

[Takashi Yano]

- NtReadFile() and NtWriteFile() seems to return STATUS_PENDING
  occasionally even in nonblocking mode. This patch adds handling
  for STATUS_PENDING in nonblocking mode.

Addresses:
  https://cygwin.com/pipermail/cygwin/2021-November/249910.html
---
 winsup/cygwin/fhandler_pipe.cc | 10 ++++++----
 winsup/cygwin/release/3.3.3    |  5 +++++
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc
index 1ebf4de10..f70ff56fe 100644
--- a/winsup/cygwin/fhandler_pipe.cc
+++ b/winsup/cygwin/fhandler_pipe.cc
@@ -336,9 +336,10 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
 	break;
       status = NtReadFile (get_handle (), evt, NULL, NULL, &io, ptr,
 			   len1, NULL, NULL);
-      if (evt && status == STATUS_PENDING)
+      if (status == STATUS_PENDING)
 	{
-	  waitret = cygwait (evt, INFINITE, cw_cancel | cw_sig);
+	  HANDLE w = evt ?: get_handle ();
+	  waitret = cygwait (w, 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.
@@ -507,10 +508,11 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
 	    break;
 	  len1 >>= 1;
 	}
-      if (evt && status == STATUS_PENDING)
+      if (status == STATUS_PENDING)
 	{
+	  HANDLE w = evt ?: get_handle ();
 	  while (WAIT_TIMEOUT ==
-		 (waitret = cygwait (evt, (DWORD) 0, cw_cancel | cw_sig)))
+		 (waitret = cygwait (w, (DWORD) 0, cw_cancel | cw_sig)))
 	    {
 	      if (reader_closed ())
 		{
diff --git a/winsup/cygwin/release/3.3.3 b/winsup/cygwin/release/3.3.3
index 1eb25e2fc..49c1bcdc3 100644
--- a/winsup/cygwin/release/3.3.3
+++ b/winsup/cygwin/release/3.3.3
@@ -16,3 +16,8 @@ Bug Fixes
 - Fix long-standing problem that new files don't get created with the
   FILE_ATTRIBUTE_ARCHIVE DOS attribute set.
   Addresses: https://cygwin.com/pipermail/cygwin/2021-November/249909.html
+
+- Fix issue that pipe read()/write() occationally returns a garnage
+  length when NtReadFile/NtWriteFile returns STATUS_PENDING in non-
+  blocking mode.
+  Addresses: https://cygwin.com/pipermail/cygwin/2021-November/249910.html
-- 
2.33.0