Linux Sandbox: always discover Zygote PID properly

content/zygote/zygote_main_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.
 
 #include "content/zygote/zygote_main.h"
 
 #include <dlfcn.h>
 #include <fcntl.h>
 #include <pthread.h>
 #include <signal.h>
@@ skipping 515 matching lines @@
   if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kNoSandbox)) {
     // This will pre-initialize the various sandboxes that need it.
     linux_sandbox->PreinitializeSandbox();
   }
 
   const bool using_setuid_sandbox =
       linux_sandbox->setuid_sandbox_client()->IsSuidSandboxChild();
   const bool using_namespace_sandbox =
       sandbox::NamespaceSandbox::InNewUserNamespace();
+  const bool using_layer1_sandbox =
+      using_setuid_sandbox || using_namespace_sandbox;
 
   if (using_setuid_sandbox) {
     linux_sandbox->setuid_sandbox_client()->CloseDummyFile();
+  }
 
+  if (using_layer1_sandbox) {
     // Let the ZygoteHost know we're booting up.
     CHECK(UnixDomainSocket::SendMsg(kZygoteSocketPairFd,
                                     kZygoteBootMessage,
                                     sizeof(kZygoteBootMessage),
                                     std::vector<int>()));
   }
 
   VLOG(1) << "ZygoteMain: initializing " << fork_delegates.size()
           << " fork delegates";
-  const bool using_layer1_sandbox =
-      using_setuid_sandbox || using_namespace_sandbox;
   for (ZygoteForkDelegate* fork_delegate : fork_delegates) {
     fork_delegate->Init(GetSandboxFD(), using_layer1_sandbox);
   }
 
   const std::vector<int> sandbox_fds_to_close_post_fork =
       linux_sandbox->GetFileDescriptorsToClose();
 
   fds_to_close_post_fork.insert(fds_to_close_post_fork.end(),
                                 sandbox_fds_to_close_post_fork.begin(),
                                 sandbox_fds_to_close_post_fork.end());
@@ skipping 32 matching lines @@
   const bool namespace_sandbox_engaged = sandbox_flags & kSandboxLinuxUserNS;
   CHECK_EQ(using_namespace_sandbox, namespace_sandbox_engaged);
 
   Zygote zygote(sandbox_flags, fork_delegates.Pass(), extra_children,
                 extra_fds);
   // This function call can return multiple times, once per fork().
   return zygote.ProcessRequests();
 }
 
 }  // namespace content