Added FD_CLOEXEC flag to client/server socket file descriptors

runtime/bin/socket_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 <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
@@ skipping 11 matching lines @@
   intptr_t fd;
   struct hostent* server;
   struct sockaddr_in server_address;
 
   fd = TEMP_FAILURE_RETRY(socket(AF_INET, SOCK_STREAM, 0));
   if (fd < 0) {
     fprintf(stderr, "Error CreateConnect: %s\n", strerror(errno));
     return -1;
   }
 
+  FDUtils::SetCloseOnExec(fd);
   FDUtils::SetNonBlocking(fd);
 
   server = gethostbyname(host);
   if (server == NULL) {
     TEMP_FAILURE_RETRY(close(fd));
     fprintf(stderr, "Error CreateConnect: %s\n", strerror(errno));
     return -1;
   }
 
   server_address.sin_family = AF_INET;
@@ skipping 138 matching lines @@
   if (s_addr == INADDR_NONE) {
     return -5;
   }
 
   fd = TEMP_FAILURE_RETRY(socket(AF_INET, SOCK_STREAM, 0));
   if (fd < 0) {
     fprintf(stderr, "Error CreateBind: %s\n", strerror(errno));
     return -1;
   }
 
+  FDUtils::SetCloseOnExec(fd);
+
   int optval = 1;
   TEMP_FAILURE_RETRY(
       setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)));
 
   server_address.sin_family = AF_INET;
   server_address.sin_port = htons(port);
   server_address.sin_addr.s_addr = s_addr;
   memset(&server_address.sin_zero, 0, sizeof(server_address.sin_zero));
 
   if (TEMP_FAILURE_RETRY(
@@ skipping 26 matching lines @@
       // error. We got woken up from the poll on the listening socket,
       // but there is no connection ready to be accepted.
       ASSERT(kTemporaryFailure != -1);
       socket = kTemporaryFailure;
     }
   } else {
     FDUtils::SetNonBlocking(socket);
   }
   return socket;
 }