Mojo: Move PlatformChannelPair to its own files.

mojo/system/platform_channel_posix.cc

-// Copyright 2013 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 "mojo/system/platform_channel.h"
-
-#include <fcntl.h>
-#include <sys/socket.h>
-#include <sys/types.h>
-#include <unistd.h>
-
-#include "base/command_line.h"
-#include "base/logging.h"
-#include "base/posix/global_descriptors.h"
-#include "base/strings/string_number_conversions.h"
-
-namespace mojo {
-namespace system {
-
-namespace {
-
-const char kMojoChannelDescriptorSwitch[] = "mojo-channel-descriptor";
-
-bool IsTargetDescriptorUsed(
-    const base::FileHandleMappingVector& file_handle_mapping,
-    int target_fd) {
-  for (size_t i = 0; i < file_handle_mapping.size(); i++) {
-    if (file_handle_mapping[i].second == target_fd)
-      return true;
-  }
-  return false;
-}
-
-}  // namespace
-
-PlatformChannelPair::PlatformChannelPair() {
-  // Create the Unix domain socket and set the ends to nonblocking.
-  int fds[2];
-  // TODO(vtl): Maybe fail gracefully if |socketpair()| fails.
-  PCHECK(socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0);
-  PCHECK(fcntl(fds[0], F_SETFL, O_NONBLOCK) == 0);
-  PCHECK(fcntl(fds[1], F_SETFL, O_NONBLOCK) == 0);
-
-  server_handle_.fd = fds[0];
-  DCHECK(server_handle_.is_valid());
-  client_handle_.fd = fds[1];
-  DCHECK(client_handle_.is_valid());
-}
-
-// static
-scoped_ptr<PlatformChannel>
-PlatformChannelPair::CreateClientChannelFromParentProcess(
-    const CommandLine& command_line) {
-  std::string client_fd_string =
-      command_line.GetSwitchValueASCII(kMojoChannelDescriptorSwitch);
-  int client_fd = -1;
-  if (client_fd_string.empty() ||
-      !base::StringToInt(client_fd_string, &client_fd) ||
-      client_fd < base::GlobalDescriptors::kBaseDescriptor) {
-    LOG(ERROR) << "Missing or invalid --" << kMojoChannelDescriptorSwitch;
-    return scoped_ptr<PlatformChannel>();
-  }
-
-  return PlatformChannel::CreateFromHandle(PlatformChannelHandle(client_fd));
-}
-
-void PlatformChannelPair::PrepareToPassClientChannelToChildProcess(
-    CommandLine* command_line,
-    base::FileHandleMappingVector* file_handle_mapping) const {
-  DCHECK(command_line);
-  DCHECK(file_handle_mapping);
-  // This is an arbitrary sanity check. (Note that this guarantees that the loop
-  // below will terminate sanely.)
-  CHECK_LT(file_handle_mapping->size(), 1000u);
-
-  DCHECK(client_handle_.is_valid());
-
-  // Find a suitable FD to map our client handle to in the child process.
-  // This has quadratic time complexity in the size of |*file_handle_mapping|,
-  // but |*file_handle_mapping| should be very small (usually/often empty).
-  int target_fd = base::GlobalDescriptors::kBaseDescriptor;
-  while (IsTargetDescriptorUsed(*file_handle_mapping, target_fd))
-    target_fd++;
-
-  file_handle_mapping->push_back(std::pair<int, int>(client_handle_.fd,
-                                                     target_fd));
-  // Log a warning if the command line already has the switch, but "clobber" it
-  // anyway, since it's reasonably likely that all the switches were just copied
-  // from the parent.
-  LOG_IF(WARNING, command_line->HasSwitch(kMojoChannelDescriptorSwitch))
-      << "Child command line already has switch --"
-      << kMojoChannelDescriptorSwitch << "="
-      << command_line->GetSwitchValueASCII(kMojoChannelDescriptorSwitch);
-  // (Any existing switch won't actually be removed from the command line, but
-  // the last one appended takes precedence.)
-  command_line->AppendSwitchASCII(kMojoChannelDescriptorSwitch,
-                                  base::IntToString(target_fd));
-}
-
-void PlatformChannelPair::ChildProcessLaunched() {
-  DCHECK(client_handle_.is_valid());
-  client_handle_.CloseIfNecessary();
-}
-
-}  // namespace system
-}  // namespace mojo