Pass StatsTable shared memory via global descriptors on Posix rather than using named shared memory.

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 "components/nacl/common/nacl_helper_linux.h"
 
 #include <errno.h>
 #include <fcntl.h>
@@ skipping 59 matching lines @@
 // Start the NaCl loader in a child created by the NaCl loader Zygote.
 void ChildNaClLoaderInit(const std::vector<int>& child_fds,
                          const NaClLoaderSystemInfo& system_info) {
   bool validack = false;
   const size_t kMaxReadSize = 1024;
   char buffer[kMaxReadSize];
   // Wait until the parent process has discovered our PID.  We
   // should not fork any child processes (which the seccomp
   // sandbox does) until then, because that can interfere with the
   // parent's discovery of our PID.
-  const int nread = HANDLE_EINTR(read(child_fds[kNaClParentFDIndex], buffer,
-                                      kMaxReadSize));
+  const int nread = HANDLE_EINTR(
+      read(child_fds[kNaClParentFDIndex(child_fds.size())], buffer,
+           kMaxReadSize));
   const std::string switch_prefix = std::string("--") +
       switches::kProcessChannelID + std::string("=");
   const size_t len = switch_prefix.length();
 
   if (nread < 0) {
     perror("read");
     LOG(ERROR) << "read returned " << nread;
   } else if (nread > static_cast<int>(len)) {
     if (switch_prefix.compare(0, len, buffer, 0, len) == 0) {
       VLOG(1) << "NaCl loader is synchronised with Chrome zygote";
       CommandLine::ForCurrentProcess()->AppendSwitchASCII(
           switches::kProcessChannelID,
           std::string(&buffer[len], nread - len));
       validack = true;
     }
   }
-  if (HANDLE_EINTR(close(child_fds[kNaClDummyFDIndex])) != 0)
+  if (HANDLE_EINTR(close(child_fds[kNaClDummyFDIndex(child_fds.size())])) != 0)
     LOG(ERROR) << "close(child_fds[kNaClDummyFDIndex]) failed";
-  if (HANDLE_EINTR(close(child_fds[kNaClParentFDIndex])) != 0)
+  if (HANDLE_EINTR(close(child_fds[kNaClParentFDIndex(child_fds.size())])) != 0)
     LOG(ERROR) << "close(child_fds[kNaClParentFDIndex]) failed";
   if (validack) {
     BecomeNaClLoader(child_fds, system_info);
   } else {
     LOG(ERROR) << "Failed to synch with zygote";
   }
   _exit(1);
 }
 
 // Handle a fork request from the Zygote.
 // Some of this code was lifted from
 // content/browser/zygote_main_linux.cc:ForkWithRealPid()
 bool HandleForkRequest(const std::vector<int>& child_fds,
                        const NaClLoaderSystemInfo& system_info,
                        Pickle* output_pickle) {
-  if (kNaClParentFDIndex + 1 != child_fds.size()) {
+  if (kNaClParentFDIndex(child_fds.size()) + 1 != child_fds.size()) {
     LOG(ERROR) << "nacl_helper: unexpected number of fds, got "
         << child_fds.size();
     return false;
   }
 
   VLOG(1) << "nacl_helper: forking";
   pid_t child_pid = fork();
   if (child_pid < 0) {
     PLOG(ERROR) << "*** fork() failed.";
   }
@@ skipping 258 matching lines @@
   // Now handle requests from the Zygote.
   while (true) {
     bool request_handled = HandleZygoteRequest(kNaClZygoteDescriptor,
                                                system_info);
     // Do not turn this into a CHECK() without thinking about robustness
     // against malicious IPC requests.
     DCHECK(request_handled);
   }
   NOTREACHED();
 }