Use ForkWithFlags on the zygote.

content/zygote/zygote_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_linux.h"
 
 #include <fcntl.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/types.h>
@@ skipping 15 matching lines @@
 #include "content/common/sandbox_linux/sandbox_linux.h"
 #include "content/common/set_process_title.h"
 #include "content/common/zygote_commands_linux.h"
 #include "content/public/common/content_descriptors.h"
 #include "content/public/common/result_codes.h"
 #include "content/public/common/sandbox_linux.h"
 #include "content/public/common/send_zygote_child_ping_linux.h"
 #include "content/public/common/zygote_fork_delegate_linux.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_switches.h"
+#include "sandbox/linux/services/syscall_wrappers.h"
 
 #if defined(ADDRESS_SANITIZER)
 #include <sanitizer/asan_interface.h>
 #endif
 
 // See http://code.google.com/p/chromium/wiki/LinuxZygote
 
 namespace content {
 
 namespace {
@@ skipping 321 matching lines @@
     }
     std::vector<int> fds;
     fds.push_back(ipc_channel_fd);  // kBrowserFDIndex
     fds.push_back(pid_oracle.get());  // kPIDOracleFDIndex
     pid = helper->Fork(process_type, fds, channel_id);
 
     // Helpers should never return in the child process.
     CHECK_NE(pid, 0);
   } else {
     CreatePipe(&read_pipe, &write_pipe);
-    pid = fork();
+    // This is roughly equivalent to a fork(). We are using ForkWithFlags mainly
+    // to give it some more diverse test coverage.
+    pid = sandbox::ForkWithFlags(SIGCHLD, nullptr, nullptr);
   }
 
   if (pid == 0) {
     // In the child process.
     write_pipe.reset();
 
     // Ping the PID oracle socket so the browser can find our PID.
     CHECK(SendZygoteChildPing(pid_oracle.get()));
 
     // Now read back our real PID from the zygote.
@@ skipping 197 matching lines @@
                                     PickleIterator iter) {
   if (HANDLE_EINTR(write(fd, &sandbox_flags_, sizeof(sandbox_flags_))) !=
                    sizeof(sandbox_flags_)) {
     PLOG(ERROR) << "write";
   }
 
   return false;
 }
 
 }  // namespace content