Make GlobalDescriptors::MaybeGet return -1 when the key is not found.

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>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/socket.h>
 #include <sys/types.h>
 
 #include <string>
 #include <vector>
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/eintr_wrapper.h"
+#include "base/global_descriptors_posix.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/posix/unix_domain_socket.h"
 #include "base/rand_util.h"
 #include "chrome/nacl/nacl_listener.h"
 #include "crypto/nss_util.h"
+#include "ipc/ipc_descriptors.h"
 #include "ipc/ipc_switches.h"
 #include "native_client/src/trusted/service_runtime/sel_addrspace.h"
 
 namespace {
 
 bool g_suid_sandbox_active;
 
 // 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) {
   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 as expected by Chrome on fd 3
-  // The zygote takes care of putting the sandbox IPC channel on fd 5
+  // 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);
   }
 
   MessageLoopForIO main_message_loop;
   NaClListener listener;
   listener.Listen();
   _exit(0);
@@ skipping 174 matching lines @@
       }
     }
     // 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
 }