Stop printing when stdout is closed.

runtime/bin/eventhandler_macos.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_MACOS)
 
 #include "bin/eventhandler.h"
 
 #include <errno.h>  // NOLINT
@@ skipping 217 matching lines @@
       } else if ((msg.data & (1 << kShutdownWriteCommand)) != 0) {
         ASSERT(msg.data == (1 << kShutdownWriteCommand));
         // Close the socket for writing.
         sd->ShutdownWrite();
         UpdateKqueue(kqueue_fd_, sd);
       } else if ((msg.data & (1 << kCloseCommand)) != 0) {
         ASSERT(msg.data == (1 << kCloseCommand));
         // Close the socket and free system resources.
         RemoveFromKqueue(kqueue_fd_, sd);
         intptr_t fd = sd->fd();
-        sd->Close();
+        if (fd == STDOUT_FILENO) {
+          // If stdout, redirect fd to /dev/null.
+          USE(dup2(open("/dev/null", O_WRONLY), STDOUT_FILENO));
+        } else {
+          sd->Close();
+        }
         socket_map_.Remove(GetHashmapKeyFromFd(fd), GetHashmapHashFromFd(fd));
         delete sd;
       } else {
         if ((msg.data & (1 << kInEvent)) != 0 && sd->IsClosedRead()) {
           DartUtils::PostInt32(msg.dart_port, 1 << kCloseEvent);
         } else {
           // Setup events to wait for.
           sd->SetPortAndMask(msg.dart_port, msg.data);
           UpdateKqueue(kqueue_fd_, sd);
         }
@@ skipping 188 matching lines @@
 
 uint32_t EventHandlerImplementation::GetHashmapHashFromFd(intptr_t fd) {
   // The hashmap does not support keys with value 0.
   return dart::Utils::WordHash(fd + 1);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)