* fhandler.h (fhandler_base::has_ongoing_io): Declare new function.

* fhandler.cc (fhandler_base::has_ongoing_io): Define new function.
(fhandler_base::read_overlapped): Use has_ongoing_io to avoid writing when
handle has not completed last I/O.
(fhandler_base::write_overlapped): Ditto.
* select.cc (peek_pipe): Be more careful about accessing hEvent field from
get_overlapped().

4 files changed, 53 insertions, 12 deletions

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index b5197b6..24a66be 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,10 +1,28 @@
 2009-06-28  Christopher Faylor  <me+cygwin@cgf.cx>
 
+	* fhandler.h (fhandler_base::has_ongoing_io): Declare new function.
+	* fhandler.cc (fhandler_base::has_ongoing_io): Define new function.
+	(fhandler_base::read_overlapped): Use has_ongoing_io to avoid writing
+	when handle has not completed last I/O.
+	(fhandler_base::write_overlapped): Ditto.
+	* select.cc (peek_pipe): Be more careful about accessing hEvent field
+	from get_overlapped().
+
+2009-06-28  Christopher Faylor  <me+cygwin@cgf.cx>
+
 	* gendef (cleanup): Rename from 'nocr'.  Remove comments and trailing
 	spaces.
 	* cygwin.din: Add long-needed comment describing what
 	dll_crt0__FP11per_process demangles to.
 
+	* select.cc (peek_pipe): Flag handle as not ready for write if event is
+	not signalled.
+	* fhandler.cc (fhandler_base::setup_overlapped): Establish event as
+	already signalled.
+	(fhandler_base::wait_overlapped): Don't reset event after we've
+	successfully waited.  MSDN documentation says that this happens
+	automatically after a WriteFileEx/ReadFileEx.
+
 2009-06-26  Corinna Vinschen  <corinna@vinschen.de>
 
 	* wincap.h (wincaps::has_broken_alloc_console): New element.
diff --git a/winsup/cygwin/fhandler.cc b/winsup/cygwin/fhandler.cc
index da656ce..650cca9 100644
--- a/winsup/cygwin/fhandler.cc
+++ b/winsup/cygwin/fhandler.cc
@@ -1763,33 +1763,55 @@ fhandler_base::wait_overlapped (bool inres, bool writing, DWORD *bytes, DWORD le
   return res;
 }
 
-void
+bool __stdcall
+fhandler_base::has_ongoing_io ()
+{
+  if (get_overlapped () && get_overlapped ()->hEvent
+      && WaitForSingleObject (get_overlapped ()->hEvent, 0) != WAIT_OBJECT_0)
+    {
+      set_errno (EAGAIN);
+      return true;
+    }
+  return false;
+}
+
+void __stdcall
 fhandler_base::read_overlapped (void *ptr, size_t& len)
 {
-  DWORD bytes_read;
+  DWORD nbytes;
   while (1)
     {
-      bool res = ReadFile (get_handle (), ptr, len, &bytes_read,
+      if (has_ongoing_io ())
+	{
+	  nbytes = (DWORD) -1;
+	  break;
+	}
+      bool res = ReadFile (get_handle (), ptr, len, &nbytes,
 			   get_overlapped ());
-      int wres = wait_overlapped (res, false, &bytes_read);
+      int wres = wait_overlapped (res, false, &nbytes);
       if (wres || !_my_tls.call_signal_handler ())
 	break;
     }
-  len = (size_t) bytes_read;
+  len = (size_t) nbytes;
 }
 
-int
+int __stdcall
 fhandler_base::write_overlapped (const void *ptr, size_t len)
 {
-  DWORD bytes_written;
+  DWORD nbytes;
   while (1)
     {
-      bool res = WriteFile (get_output_handle (), ptr, len, &bytes_written,
+      if (has_ongoing_io ())
+	{
+	  nbytes = (DWORD) -1;
+	  break;
+	}
+      bool res = WriteFile (get_output_handle (), ptr, len, &nbytes,
 			    get_overlapped ());
-      int wres = wait_overlapped (res, true, &bytes_written, (size_t) len);
+      int wres = wait_overlapped (res, true, &nbytes, (size_t) len);
       if (wres || !_my_tls.call_signal_handler ())
 	break;
     }
-  debug_printf ("returning %u", bytes_written);
-  return bytes_written;
+  debug_printf ("returning %u", nbytes);
+  return nbytes;
 }
diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 1efd8fd..a4cc50f 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -302,6 +302,7 @@ class fhandler_base
   virtual char const *ttyname () { return get_name (); }
   virtual void __stdcall read (void *ptr, size_t& len) __attribute__ ((regparm (3)));
   virtual void __stdcall read_overlapped (void *ptr, size_t& len) __attribute__ ((regparm (3)));
+  virtual bool __stdcall has_ongoing_io () __attribute__ ((regparm (1)));
   virtual int write (const void *ptr, size_t len);
   virtual int __stdcall write_overlapped (const void *ptr, size_t len);
   virtual ssize_t readv (const struct iovec *, int iovcnt, ssize_t tot = -1);
diff --git a/winsup/cygwin/select.cc b/winsup/cygwin/select.cc
index c3dc005..26cb3b4 100644
--- a/winsup/cygwin/select.cc
+++ b/winsup/cygwin/select.cc
@@ -513,7 +513,7 @@ out:
       else if (fh->get_device () == FH_PIPER)
 	select_printf ("%s, select for write on read end of pipe",
 		       fh->get_name ());
-      else if (fh->get_overlapped ()->hEvent
+      else if (fh->get_overlapped () && fh->get_overlapped ()->hEvent
 	       && WaitForSingleObject (fh->get_overlapped ()->hEvent, 0)
 	           != WAIT_OBJECT_0)
 	s->write_ready = false;