Turn FileDescriptorInfo a collection class

content/browser/child_process_launcher.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/browser/child_process_launcher.h"
 
 #include <utility>  // For std::pair.
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 183 matching lines @@
     if (launch_elevated) {
       base::LaunchOptions options;
       options.start_hidden = true;
       base::LaunchElevatedProcess(*cmd_line, options, &handle);
     } else {
       handle = StartSandboxedProcess(delegate, cmd_line);
     }
 #elif defined(OS_POSIX)
     std::string process_type =
         cmd_line->GetSwitchValueASCII(switches::kProcessType);
-    std::vector<FileDescriptorInfo> files_to_register;
-    files_to_register.push_back(
-        FileDescriptorInfo(kPrimaryIPCChannel,
-                           base::FileDescriptor(ipcfd, false)));
+    scoped_ptr<FileDescriptorInfo> files_to_register =
+        make_scoped_ptr(new FileDescriptorInfo());
+    files_to_register->Share(kPrimaryIPCChannel, ipcfd);
     base::StatsTable* stats_table = base::StatsTable::current();
     if (stats_table &&
         base::SharedMemory::IsHandleValid(
             stats_table->GetSharedMemoryHandle())) {
-      files_to_register.push_back(
-          FileDescriptorInfo(kStatsTableSharedMemFd,
-                             stats_table->GetSharedMemoryHandle()));
+      base::FileDescriptor fd = stats_table->GetSharedMemoryHandle();
+      DCHECK(fd.auto_close);
+      files_to_register->Transfer(kStatsTableSharedMemFd,
+                                  base::ScopedFD(fd.fd));
     }
 #endif
 
 #if defined(OS_ANDROID)
     // Android WebView runs in single process, ensure that we never get here
     // when running in single process mode.
     CHECK(!cmd_line->HasSwitch(switches::kSingleProcess));
 
-    GetContentClient()->browser()->
-        GetAdditionalMappedFilesForChildProcess(*cmd_line, child_process_id,
-                                                &files_to_register);
+    GetContentClient()->browser()->GetAdditionalMappedFilesForChildProcess(
+        *cmd_line, child_process_id, files_to_register.get());
 
-    StartChildProcess(cmd_line->argv(), child_process_id, files_to_register,
+    StartChildProcess(
+        cmd_line->argv(),
+        child_process_id,
+        files_to_register.Pass(),
         base::Bind(&ChildProcessLauncher::Context::OnChildProcessStarted,
-                   this_object, client_thread_id, begin_launch_time));
+                   this_object,
+                   client_thread_id,
+                   begin_launch_time));
 
 #elif defined(OS_POSIX)
     base::ProcessHandle handle = base::kNullProcessHandle;
     // We need to close the client end of the IPC channel to reliably detect
     // child termination.
     base::ScopedFD ipcfd_closer(ipcfd);
 
 #if !defined(OS_MACOSX)
-    GetContentClient()->browser()->
-        GetAdditionalMappedFilesForChildProcess(*cmd_line, child_process_id,
-                                                &files_to_register);
+    GetContentClient()->browser()->GetAdditionalMappedFilesForChildProcess(
+        *cmd_line, child_process_id, files_to_register.get());
     if (use_zygote) {
-      handle = ZygoteHostImpl::GetInstance()->ForkRequest(cmd_line->argv(),
-                                                          files_to_register,
-                                                          process_type);
+      handle = ZygoteHostImpl::GetInstance()->ForkRequest(
+          cmd_line->argv(), files_to_register.Pass(), process_type);
     } else
     // Fall through to the normal posix case below when we're not zygoting.
 #endif  // !defined(OS_MACOSX)
     {
       // Convert FD mapping to FileHandleMappingVector
-      base::FileHandleMappingVector fds_to_map;
-      for (size_t i = 0; i < files_to_register.size(); ++i) {
-        fds_to_map.push_back(std::make_pair(
-            files_to_register[i].fd.fd,
-            files_to_register[i].id +
-                base::GlobalDescriptors::kBaseDescriptor));
+      base::FileHandleMappingVector fds_to_map =
+          files_to_register->descriptors();
+      for (size_t i = 0; i < fds_to_map.size(); ++i) {
+        fds_to_map[i].second += base::GlobalDescriptors::kBaseDescriptor;

[mdempsky, 2014/09/22 18:30:51]

I know FileHandleMappingVector predates your CL, but I feel like this is a
really bad API: "first" and "second" are both ints, so from just reading the new
code in isolation, it's entirely unobvious what's going on here.

It also at first strikes me initially as a mistake that you've made a copy for
fds_to_map, and also that you're using +=.  I feel like the new logic is subtle
enough to warrant a better comment.  Something like "Make a copy of the file
descriptor mapping vector and adjust the IDs by kBaseDescriptor."

[Hajime Morrita, 2014/09/22 22:59:26]

Agreed. I cannot kill FileHandleMappingVector so let me hide the weird part
behind a FileDescriporInfo API.

       }
 
 #if !defined(OS_MACOSX)
       if (process_type == switches::kRendererProcess) {
         const int sandbox_fd =
             RenderSandboxHostLinux::GetInstance()->GetRendererSocket();
         fds_to_map.push_back(std::make_pair(
             sandbox_fd,
             GetSandboxFD()));
       }
@@ skipping 251 matching lines @@
          GetHandle(), background));
 }
 
 void ChildProcessLauncher::SetTerminateChildOnShutdown(
     bool terminate_on_shutdown) {
   if (context_.get())
     context_->set_terminate_child_on_shutdown(terminate_on_shutdown);
 }
 
 }  // namespace content