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