Zygote: create variables for magic fd numbers

content/common/zygote_commands_linux.h

 // 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.
 
 #ifndef CONTENT_COMMON_ZYGOTE_COMMANDS_LINUX_H_
 #define CONTENT_COMMON_ZYGOTE_COMMANDS_LINUX_H_
 
 namespace content {
 
 // Contents of the initial message sent from the zygote to the browser when it
 // is ready to go.
 static const char kZygoteHelloMessage[] = "ZYGOTE_OK";
 
+// File descriptors initialized by the Zygote Host
+const int kZygoteSocketPairFd = 3;
+const int kZygoteRendererSocketFd = 5;
+// This file descriptor is special. It is passed to the Zygote and a setuid
+// helper will be called to locate the process of the Zygote on the system.
+// This mechanism is used when multiple PID namespaces exist because of the
+// setuid sandbox.
+// It is very important that this file descriptor does not exist in multiple
+// processes.
+const int kZygoteIdFd = 7;
+
 // These are the command codes used on the wire between the browser and the
 // zygote.
 enum {
   // Fork off a new renderer.
   kZygoteCommandFork = 0,
 
   // Reap a renderer child.
   kZygoteCommandReap = 1,
 
   // Check what happend to a child process.
   kZygoteCommandGetTerminationStatus = 2,
 
   // Read a bitmask of kSandboxLinux*
   kZygoteCommandGetSandboxStatus = 3
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_ZYGOTE_COMMANDS_LINUX_H_