* fhandler.h (class fhandler_base): Add was_nonblocking status flag.

	* fhandler.cc (fhandler_base::set_flags): Set was_nonblocking if the
	O_NONBLOCK flag has been specified.
	(fhandler_base_overlapped::close): Check for was_nonblocking instead
	of for is_nonblocking.  Explain why.
	(fhandler_base::set_nonblocking): Set was_nonblocking if noblocking
	mode gets enabled.

4 files changed, 33 insertions, 4 deletions

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 746881500..21a62461e 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,13 @@
+2015-02-24  Corinna Vinschen  <corinna@vinschen.de>
+
+	* fhandler.h (class fhandler_base): Add was_nonblocking status flag.
+	* fhandler.cc (fhandler_base::set_flags): Set was_nonblocking if the
+	O_NONBLOCK flag has been specified.
+	(fhandler_base_overlapped::close): Check for was_nonblocking instead
+	of for is_nonblocking.  Explain why.
+	(fhandler_base::set_nonblocking): Set was_nonblocking if noblocking
+	mode gets enabled.
+
 2015-02-24  Ken Brown  <kbrown@cornell.edu>
 
 	* include/sys/socket.h (sockatmark): Add prototype.
diff --git a/winsup/cygwin/fhandler.cc b/winsup/cygwin/fhandler.cc
index 8444d4abc..6f024da32 100644
--- a/winsup/cygwin/fhandler.cc
+++ b/winsup/cygwin/fhandler.cc
@@ -1,7 +1,7 @@
 /* fhandler.cc.  See console.cc for fhandler_console functions.
 
    Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
-   2007, 2008, 2009, 2010, 2011, 2012, 2013 Red Hat, Inc.
+   2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015 Red Hat, Inc.
 
 This file is part of Cygwin.
 
@@ -205,6 +205,8 @@ fhandler_base::set_flags (int flags, int supplied_bin)
     bin = wbinary () || rbinary () ? O_BINARY : O_TEXT;
 
   openflags = flags | bin;
+  if (openflags & O_NONBLOCK)
+    was_nonblocking (true);
 
   bin &= O_BINARY;
   rbinary (bin ? true : false);
@@ -1242,8 +1244,13 @@ fhandler_base_overlapped::close ()
   int res;
   int writer = (get_access () & GENERIC_WRITE);
   /* Need to treat non-blocking I/O specially because Windows appears to
-     be brain-dead  */
-  if (writer && is_nonblocking () && has_ongoing_io ())
+     be brain-dead.  We're checking here if the descriptor was ever set
+     to nonblocking, rather than checking if it's nonblocking at close time.
+     The reason is that applications may switch back to blocking (for the
+     sake of some other application accessing this descriptor) without
+     performaing any further I/O.  These applications would suffer data
+     loss, which this workaround is trying to fix. */
+  if (writer && was_nonblocking () && has_ongoing_io ())
     {
       clone (HEAP_3_FHANDLER)->check_later ();
       res = 0;
@@ -1629,6 +1636,8 @@ fhandler_base::set_nonblocking (int yes)
   int current = openflags & O_NONBLOCK_MASK;
   int new_flags = yes ? (!current ? O_NONBLOCK : current) : 0;
   openflags = (openflags & ~O_NONBLOCK_MASK) | new_flags;
+  if (new_flags)
+    was_nonblocking (true);
 }
 
 int
diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 0298a6f6a..10eacd106 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -149,12 +149,16 @@ class fhandler_base
     unsigned need_fork_fixup    : 1; /* Set if need to fixup after fork. */
     unsigned isclosed		: 1; /* Set when fhandler is closed. */
     unsigned mandatory_locking	: 1; /* Windows mandatory locking */
+    unsigned was_nonblocking	: 1; /* Set when setting O_NONBLOCK.  Never
+					reset.  This is for the sake of
+					fhandler_base_overlapped::close. */
 
    public:
     status_flags () :
       rbinary (0), rbinset (0), wbinary (0), wbinset (0), nohandle (0),
       did_lseek (0), query_open (no_query), close_on_exec (0),
-      need_fork_fixup (0), isclosed (0), mandatory_locking (0)
+      need_fork_fixup (0), isclosed (0), mandatory_locking (0),
+      was_nonblocking (0)
       {}
   } status, open_status;
 
@@ -250,6 +254,7 @@ class fhandler_base
   IMPLEMENT_STATUS_FLAG (bool, need_fork_fixup)
   IMPLEMENT_STATUS_FLAG (bool, isclosed)
   IMPLEMENT_STATUS_FLAG (bool, mandatory_locking)
+  IMPLEMENT_STATUS_FLAG (bool, was_nonblocking)
 
   int get_default_fmode (int flags);
 
diff --git a/winsup/cygwin/release/1.7.35 b/winsup/cygwin/release/1.7.35
index 564698907..93335bcdb 100644
--- a/winsup/cygwin/release/1.7.35
+++ b/winsup/cygwin/release/1.7.35
@@ -7,6 +7,8 @@ What's new:
 What changed:
 -------------
 
+- Performance improvements of the new account DB handling.
+
 
 Bug Fixes
 ---------
@@ -38,3 +40,6 @@ Bug Fixes
 
 - 64 bit: Avoid misbehaviour in signal mask computation.
   Addresses: https://cygwin.com/ml/cygwin/2015-02/msg00665.html
+
+- Avoid data loss on non-blocking pipes after switching back to blocking.
+  Addresses: https://cygwin.com/ml/cygwin/2015-02/msg00575.html