Use RecvMsgWithPid to find zygote PID instead of chrome-sandbox

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 <errno.h>
 #include <fcntl.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/linux_util.h"
 #include "base/native_library.h"
 #include "base/pickle.h"
+#include "base/posix/eintr_wrapper.h"
 #include "base/posix/unix_domain_socket_linux.h"
 #include "base/rand_util.h"
 #include "base/sys_info.h"
 #include "build/build_config.h"
 #include "content/common/child_process_sandbox_support_impl_linux.h"
 #include "content/common/font_config_ipc_linux.h"
 #include "content/common/pepper_plugin_list.h"
 #include "content/common/sandbox_linux/sandbox_linux.h"
 #include "content/common/zygote_commands_linux.h"
 #include "content/public/common/content_switches.h"
@@ skipping 301 matching lines @@
   // Ensure access to the Pepper plugins before the sandbox is turned on.
   PreloadPepperPlugins();
 #endif
 #if defined(ENABLE_WEBRTC)
   InitializeWebRtcModule();
 #endif
   SkFontConfigInterface::SetGlobal(
       new FontConfigIPC(GetSandboxFD()))->unref();
 }
 
-static void CloseFdAndHandleEintr(int fd) {
-  close(fd);
-}
-
 static bool CreateInitProcessReaper() {
-  // This "magic" socket must only appear in one process, so make sure
-  // it gets closed in the parent after fork().
-  base::Closure zygoteid_fd_closer =
-      base::Bind(CloseFdAndHandleEintr, kZygoteIdFd);
   // The current process becomes init(1), this function returns from a
   // newly created process.
-  const bool init_created =
-      sandbox::CreateInitProcessReaper(&zygoteid_fd_closer);
+  const bool init_created = sandbox::CreateInitProcessReaper(NULL);
   if (!init_created) {
     LOG(ERROR) << "Error creating an init process to reap zombies";
     return false;
   }
   return true;
 }
 
 // Enter the setuid sandbox. This requires the current process to have been
 // created through the setuid sandbox.
 static bool EnterSuidSandbox(sandbox::SetuidSandboxClient* setuid_sandbox) {
@@ skipping 83 matching lines @@
                 ZygoteForkDelegate* forkdelegate) {
   g_am_zygote_or_renderer = true;
   sandbox::InitLibcUrandomOverrides();
 
   LinuxSandbox* linux_sandbox = LinuxSandbox::GetInstance();
   // This will pre-initialize the various sandboxes that need it.
   linux_sandbox->PreinitializeSandbox();
 
   const bool must_enable_setuid_sandbox =
       linux_sandbox->setuid_sandbox_client()->IsSuidSandboxChild();
+  if (must_enable_setuid_sandbox) {
+    // We have no use for the zygote ID descriptor anymore.

[jln (very slow on Chromium), 2014/04/26 00:54:10]

Maybe be more explicit? "kZygoteIdFd has been passed to US because of an ancient
setuid sandbox ABI requirement. It's a useless dummy, close it."

[mdempsky, 2014/04/26 06:05:58]

Done.

+    CHECK_EQ(0, IGNORE_EINTR(close(kZygoteIdFd)));
+  }
 
   if (forkdelegate != NULL) {
     VLOG(1) << "ZygoteMain: initializing fork delegate";
     forkdelegate->Init(GetSandboxFD(), must_enable_setuid_sandbox);
   } else {
     VLOG(1) << "ZygoteMain: fork delegate is NULL";
   }
 
   // Turn on the first layer of the sandbox if the configuration warrants it.
   EnterLayerOneSandbox(linux_sandbox, must_enable_setuid_sandbox);
 
   int sandbox_flags = linux_sandbox->GetStatus();
   bool setuid_sandbox_engaged = sandbox_flags & kSandboxLinuxSUID;
   CHECK_EQ(must_enable_setuid_sandbox, setuid_sandbox_engaged);
 
   Zygote zygote(sandbox_flags, forkdelegate);
   // This function call can return multiple times, once per fork().
   return zygote.ProcessRequests();
 }
 
 }  // namespace content