NaCl: Clean up file descriptor setup in nacl_helper on linux

chrome/nacl/nacl_helper_linux.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A mini-zygote specifically for Native Client.
 
 #include "chrome/common/nacl_helper_linux.h"
 
 #include <errno.h>
 #include <link.h>
@@ skipping 25 matching lines @@
 // The child must mimic the behavior of zygote_main_linux.cc on the child
 // side of the fork. See zygote_main_linux.cc:HandleForkRequest from
 //   if (!child) {
 // Note: this code doesn't attempt to support SELINUX or the SECCOMP sandbox.
 void BecomeNaClLoader(const std::vector<int>& child_fds,
                       size_t prereserved_sandbox_size) {
   VLOG(1) << "NaCl loader: setting up IPC descriptor";
   // don't need zygote FD any more
   if (HANDLE_EINTR(close(kNaClZygoteDescriptor)) != 0)
     LOG(ERROR) << "close(kNaClZygoteDescriptor) failed.";
-  // Set up browser descriptor on fd 3 and IPC as expected by Chrome.
   base::GlobalDescriptors::GetInstance()->Set(kPrimaryIPCChannel,
-      kPrimaryIPCChannel + base::GlobalDescriptors::kBaseDescriptor);
-  int zfd = dup2(child_fds[kNaClBrowserFDIndex], kNaClBrowserDescriptor);
-  if (zfd != kNaClBrowserDescriptor) {
-    LOG(ERROR) << "Could not initialize kNaClBrowserDescriptor";
-    _exit(-1);
-  }
+                                              child_fds[kNaClBrowserFDIndex]);
 
   MessageLoopForIO main_message_loop;
   NaClListener listener;
   listener.set_prereserved_sandbox_size(prereserved_sandbox_size);
   listener.Listen();
   _exit(0);
 }
 
 // Some of this code was lifted from
 // content/browser/zygote_main_linux.cc:ForkWithRealPid()
@@ skipping 204 matching lines @@
       _exit(-1);
     }
     // if fork fails, send PID=-1 to zygote
     if (!UnixDomainSocket::SendMsg(kNaClZygoteDescriptor, &badpid,
                                    sizeof(badpid), empty)) {
       LOG(ERROR) << "*** send() to zygote failed";
     }
   }
   CHECK(false);  // This routine must not return
 }