src/mojo/shell/dbus_application_loader_linux.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "mojo/shell/dbus_application_loader_linux.h"
   6
   7 #include <string>
   8
   9 #include "base/command_line.h"
  10 #include "base/location.h"
  11 #include "base/logging.h"
  12 #include "base/task_runner_util.h"
  13 #include "base/threading/thread_restrictions.h"
  14 #include "dbus/bus.h"
  15 #include "dbus/file_descriptor.h"
  16 #include "dbus/message.h"
  17 #include "dbus/object_path.h"
  18 #include "dbus/object_proxy.h"
  19 #include "mojo/dbus/dbus_external_service.h"
  20 #include "mojo/embedder/channel_init.h"
  21 #include "mojo/embedder/platform_channel_pair.h"
  22 #include "mojo/shell/context.h"
  23 #include "mojo/shell/external_service.mojom.h"
  24
  25 namespace mojo {
  26 namespace shell {
  27
  28 // Manages the connection to a single externally-running service.
  29 class DBusApplicationLoader::LoadContext {
  30  public:
  31   // Kicks off the attempt to bootstrap a connection to the externally-running
  32   // service specified by url_.
  33   // Creates a MessagePipe and passes one end over DBus to the service. Then,
  34   // calls ExternalService::Activate(ShellHandle) over the now-shared pipe.
  35   LoadContext(DBusApplicationLoader* loader,
  36               const scoped_refptr<dbus::Bus>& bus,
  37               const GURL& url,
  38               ScopedMessagePipeHandle service_provider_handle)
  39       : loader_(loader),
  40         bus_(bus),
  41         service_dbus_proxy_(NULL),
  42         url_(url),
  43         service_provider_handle_(service_provider_handle.Pass()) {
  44     base::PostTaskAndReplyWithResult(
  45         loader_->context_->task_runners()->io_runner(),
  46         FROM_HERE,
  47         base::Bind(&LoadContext::CreateChannelOnIOThread,
  48                    base::Unretained(this)),
  49         base::Bind(&LoadContext::ConnectChannel, base::Unretained(this)));
  50   }
  51
  52   virtual ~LoadContext() {}
  53
  54  private:
  55   // Sets up a pipe to share with the externally-running service and returns
  56   // the endpoint that should be sent over DBus.
  57   // The FD for the endpoint must be validated on an IO thread.
  58   scoped_ptr<dbus::FileDescriptor> CreateChannelOnIOThread() {
  59     base::ThreadRestrictions::AssertIOAllowed();
  60     CHECK(bus_->Connect());
  61     CHECK(bus_->SetUpAsyncOperations());
  62
  63     embedder::PlatformChannelPair channel_pair;
  64     channel_init_.reset(new embedder::ChannelInit);
  65     mojo::ScopedMessagePipeHandle bootstrap_message_pipe =
  66         channel_init_->Init(channel_pair.PassServerHandle().release().fd,
  67                             loader_->context_->task_runners()->io_runner());
  68     CHECK(bootstrap_message_pipe.is_valid());
  69
  70     external_service_.Bind(bootstrap_message_pipe.Pass());
  71
  72     scoped_ptr<dbus::FileDescriptor> client_fd(new dbus::FileDescriptor);
  73     client_fd->PutValue(channel_pair.PassClientHandle().release().fd);
  74     client_fd->CheckValidity();  // Must be run on an IO thread.
  75     return client_fd.Pass();
  76   }
  77
  78   // Sends client_fd over to the externally-running service. If that
  79   // attempt is successful, the service will then be "activated" by
  80   // sending it a ShellHandle.
  81   void ConnectChannel(scoped_ptr<dbus::FileDescriptor> client_fd) {
  82     size_t first_slash = url_.path().find_first_of('/');
  83     DCHECK_NE(first_slash, std::string::npos);
  84
  85     const std::string service_name = url_.path().substr(0, first_slash);
  86     const std::string object_path = url_.path().substr(first_slash);
  87     service_dbus_proxy_ =
  88         bus_->GetObjectProxy(service_name, dbus::ObjectPath(object_path));
  89
  90     dbus::MethodCall call(kMojoDBusInterface, kMojoDBusConnectMethod);
  91     dbus::MessageWriter writer(&call);
  92     writer.AppendFileDescriptor(*client_fd.get());
  93
  94     // TODO(cmasone): handle errors!
  95     service_dbus_proxy_->CallMethod(
  96         &call,
  97         dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
  98         base::Bind(&LoadContext::ActivateService, base::Unretained(this)));
  99   }
 100
 101   // Sends a ShellHandle over to the now-connected externally-running service,
 102   // using the Mojo ExternalService API.
 103   void ActivateService(dbus::Response* response) {
 104     external_service_->Activate(mojo::ScopedMessagePipeHandle(
 105         mojo::MessagePipeHandle(service_provider_handle_.release().value())));
 106   }
 107
 108   // Should the ExternalService disappear completely, destroy connection state.
 109   // NB: This triggers off of the service disappearing from
 110   // DBus. Perhaps there's a way to watch at the Mojo layer instead,
 111   // and that would be superior?
 112   void HandleNameOwnerChanged(const std::string& old_owner,
 113                               const std::string& new_owner) {
 114     DCHECK(loader_->context_->task_runners()
 115                ->shell_runner()
 116                ->BelongsToCurrentThread());
 117
 118     if (new_owner.empty()) {
 119       loader_->context_->task_runners()->shell_runner()->PostTask(
 120           FROM_HERE,
 121           base::Bind(&DBusApplicationLoader::ForgetService,
 122                      base::Unretained(loader_),
 123                      url_));
 124     }
 125   }
 126
 127   DBusApplicationLoader* const loader_;
 128   scoped_refptr<dbus::Bus> bus_;
 129   dbus::ObjectProxy* service_dbus_proxy_;  // Owned by bus_;
 130   const GURL url_;
 131   ScopedMessagePipeHandle service_provider_handle_;
 132   scoped_ptr<embedder::ChannelInit> channel_init_;
 133   ExternalServicePtr external_service_;
 134
 135   DISALLOW_COPY_AND_ASSIGN(LoadContext);
 136 };
 137
 138 DBusApplicationLoader::DBusApplicationLoader(Context* context)
 139     : context_(context) {
 140   dbus::Bus::Options options;
 141   options.bus_type = dbus::Bus::SESSION;
 142   options.dbus_task_runner = context_->task_runners()->io_runner();
 143   bus_ = new dbus::Bus(options);
 144 }
 145
 146 DBusApplicationLoader::~DBusApplicationLoader() {
 147   DCHECK(url_to_load_context_.empty());
 148 }
 149
 150 void DBusApplicationLoader::Load(ApplicationManager* manager,
 151                                  const GURL& url,
 152                                  scoped_refptr<LoadCallbacks> callbacks) {
 153   // TODO(aa): This could be delayed until later, when we know that loading is
 154   // going to succeed.
 155   ScopedMessagePipeHandle shell_handle = callbacks->RegisterApplication();
 156   if (!shell_handle.is_valid())
 157     return;
 158
 159   DCHECK(url.SchemeIs("dbus"));
 160   DCHECK(url_to_load_context_.find(url) == url_to_load_context_.end());
 161   url_to_load_context_[url] =
 162       new LoadContext(this, bus_, url, shell_handle.Pass());
 163 }
 164
 165 void DBusApplicationLoader::OnApplicationError(ApplicationManager* manager,
 166                                                const GURL& url) {
 167   // TODO(cmasone): Anything at all in this method here.
 168 }
 169
 170 void DBusApplicationLoader::ForgetService(const GURL& url) {
 171   DCHECK(context_->task_runners()->shell_runner()->BelongsToCurrentThread());
 172   DVLOG(2) << "Forgetting service (url: " << url << ")";
 173
 174   LoadContextMap::iterator it = url_to_load_context_.find(url);
 175   DCHECK(it != url_to_load_context_.end()) << url;
 176
 177   LoadContext* doomed = it->second;
 178   url_to_load_context_.erase(it);
 179
 180   delete doomed;
 181 }
 182
 183 }  // namespace shell
 184 }  // namespace mojo