Added FD_CLOEXEC flag to client/server socket file descriptors

runtime/bin/fdutils_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 <errno.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <sys/ioctl.h>
 
 #include "bin/fdutils.h"
 
 
+bool FDUtils::SetCloseOnExec(intptr_t fd) {
+  intptr_t status;
+  status = TEMP_FAILURE_RETRY(fcntl(fd, F_GETFD));
+  if (status < 0) {
+    perror("fcntl F_GETFD failed");
+    return false;
+  }
+  status |= FD_CLOEXEC;
+  if (TEMP_FAILURE_RETRY(fcntl(fd, F_SETFD, status)) < 0) {
+    perror("fcntl F_SETFD failed");
+    return false;
+  }
+  return true;
+}
+
+
 static bool SetBlockingHelper(intptr_t fd, bool blocking) {
   intptr_t status;
   status = TEMP_FAILURE_RETRY(fcntl(fd, F_GETFL));
   if (status < 0) {
     perror("fcntl F_GETFL failed");
     return false;
   }
   status = blocking ? (status & ~O_NONBLOCK) : (status | O_NONBLOCK);
   if (TEMP_FAILURE_RETRY(fcntl(fd, F_SETFL, status)) < 0) {
     perror("fcntl F_SETFL failed");
@@ skipping 87 matching lines @@
       ASSERT(errno != EWOULDBLOCK);
       return -1;
     } else {
       ASSERT(bytes_written > 0);
       remaining -= bytes_written;
       buffer_pos += bytes_written;
     }
   }
   return count;
 }