Fix bug #18420 with deadlocks communicating with subprocess on MS-Windows.

 src/w32.c (fcntl): Support O_NONBLOCK fcntl on the write side of
 pipes.
 (sys_write): When a write to a non-blocking pipe returns ENOSPC,
 set errno to EAGAIN instead, to allow the caller to retry the
 write after some waiting.  Fixes deadlocks when Emacs exchanges a
 lot of data through the pipe.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 4f851edb0fd..c32b4c44988 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,12 @@
+2014-09-14  Eli Zaretskii  <eliz@gnu.org>
+
+        * w32.c (fcntl): Support O_NONBLOCK fcntl on the write side of
+        pipes.
+        (sys_write): When a write to a non-blocking pipe returns ENOSPC,
+        set errno to EAGAIN instead, to allow the caller to retry the
+        write after some waiting.  Fixes deadlocks when Emacs exchanges a
+        lot of data through the pipe.  (Bug#18420)
+
 2014-09-13  Eli Zaretskii  <eliz@gnu.org>
 
         * sound.c (Fplay_sound_internal): Encode the sound file name in