Generalize DBus-Mojo bootstrapping code

Most of the code to bootstrap a Mojo service over DBus is
moved into a templated class under mojo/dbus. Simply implement your Mojo service
and then specialize DBusExternalService with your service implementation.

TBR=darin@chromium.org
BUG=chromium:367816
TEST=run mojo_dbus_echo_service in one shell, and then ./out/Debug/mojo_shell --origin=http://127.0.0.1:4444 --disable-cache mojo:mojo_dbus_echo in the other.

Review URL: https://codereview.chromium.org/245253004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@267662 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 184 insertions, 0 deletions

diff --git a/mojo/dbus/DEPS b/mojo/dbus/DEPS
new file mode 100644
index 0000000..0abf683
--- /dev/null
+++ b/mojo/dbus/DEPS
@@ -0,0 +1,4 @@
+include_rules = [
+  "+base",
+  "+dbus",
+]
diff --git a/mojo/dbus/dbus_external_service.cc b/mojo/dbus/dbus_external_service.cc
new file mode 100644
index 0000000..3a13cf7
--- /dev/null
+++ b/mojo/dbus/dbus_external_service.cc
@@ -0,0 +1,95 @@
+// Copyright 2014 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/dbus/dbus_external_service.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "dbus/bus.h"
+#include "dbus/exported_object.h"
+#include "dbus/file_descriptor.h"
+#include "dbus/message.h"
+#include "dbus/object_path.h"
+#include "mojo/common/channel_init.h"
+#include "mojo/public/cpp/bindings/error_handler.h"
+#include "mojo/public/cpp/bindings/remote_ptr.h"
+#include "mojo/public/cpp/shell/application.h"
+#include "mojo/public/interfaces/shell/shell.mojom.h"
+#include "mojo/shell/external_service.mojom.h"
+
+namespace mojo {
+
+DBusExternalServiceBase::DBusExternalServiceBase(
+    const std::string& service_name)
+    : service_name_(service_name),
+      exported_object_(NULL) {
+}
+DBusExternalServiceBase::~DBusExternalServiceBase() {}
+
+void DBusExternalServiceBase::Start() {
+  InitializeDBus();
+  ExportMethods();
+  TakeDBusServiceOwnership();
+  DVLOG(1) << "External service started";
+}
+
+void DBusExternalServiceBase::OnError() {
+  Disconnect();
+}
+
+void DBusExternalServiceBase::ConnectChannel(
+    dbus::MethodCall* method_call,
+    dbus::ExportedObject::ResponseSender sender) {
+  dbus::MessageReader reader(method_call);
+  dbus::FileDescriptor wrapped_fd;
+  if (!reader.PopFileDescriptor(&wrapped_fd)) {
+    sender.Run(
+        dbus::ErrorResponse::FromMethodCall(
+            method_call,
+            "org.chromium.Mojo.BadHandle",
+            "Invalid FD.").PassAs<dbus::Response>());
+    return;
+  }
+  wrapped_fd.CheckValidity();
+  channel_init_.reset(new mojo::common::ChannelInit);
+  mojo::ScopedMessagePipeHandle message_pipe =
+      channel_init_->Init(wrapped_fd.TakeValue(),
+                          base::MessageLoopProxy::current());
+  CHECK(message_pipe.is_valid());
+
+  Connect(mojo::ScopedExternalServiceHostHandle::From(message_pipe.Pass()));
+  sender.Run(dbus::Response::FromMethodCall(method_call));
+}
+
+void DBusExternalServiceBase::ExportMethods() {
+  CHECK(exported_object_);
+  CHECK(exported_object_->ExportMethodAndBlock(
+      kMojoDBusInterface, kMojoDBusConnectMethod,
+      base::Bind(&DBusExternalServiceBase::ConnectChannel,
+                 base::Unretained(this))));
+}
+
+void DBusExternalServiceBase::InitializeDBus() {
+  CHECK(!bus_);
+  dbus::Bus::Options options;
+  options.bus_type = dbus::Bus::SESSION;
+  bus_ = new dbus::Bus(options);
+  CHECK(bus_->Connect());
+  CHECK(bus_->SetUpAsyncOperations());
+
+  exported_object_ =
+      bus_->GetExportedObject(dbus::ObjectPath(kMojoDBusImplPath));
+}
+
+void DBusExternalServiceBase::TakeDBusServiceOwnership() {
+  CHECK(bus_->RequestOwnershipAndBlock(
+      service_name_,
+      dbus::Bus::REQUIRE_PRIMARY_ALLOW_REPLACEMENT))
+      << "Unable to take ownership of " << service_name_;
+}
+
+}  // namespace mojo
diff --git a/mojo/dbus/dbus_external_service.h b/mojo/dbus/dbus_external_service.h
new file mode 100644
index 0000000..1a33c4c7
--- /dev/null
+++ b/mojo/dbus/dbus_external_service.h
@@ -0,0 +1,85 @@
+// Copyright 2014 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 "base/memory/scoped_ptr.h"
+#include "dbus/bus.h"
+#include "dbus/exported_object.h"
+#include "dbus/message.h"
+#include "dbus/object_path.h"
+#include "mojo/common/channel_init.h"
+#include "mojo/public/cpp/bindings/interface.h"
+#include "mojo/public/cpp/bindings/remote_ptr.h"
+#include "mojo/public/cpp/shell/application.h"
+#include "mojo/public/interfaces/shell/shell.mojom.h"
+#include "mojo/shell/external_service.mojom.h"
+
+namespace mojo {
+const char kMojoDBusImplPath[] = "/org/chromium/MojoImpl";
+const char kMojoDBusInterface[] = "org.chromium.Mojo";
+const char kMojoDBusConnectMethod[] = "ConnectChannel";
+
+class DBusExternalServiceBase : public mojo::ErrorHandler {
+ public:
+  explicit DBusExternalServiceBase(const std::string& service_name);
+  virtual ~DBusExternalServiceBase();
+
+  void Start();
+
+ protected:
+  // TODO(cmasone): Enable multiple peers to connect/disconnect
+  virtual void Connect(ScopedExternalServiceHostHandle client_handle) = 0;
+  virtual void Disconnect() = 0;
+
+ private:
+  virtual void OnError() OVERRIDE;
+
+  // Implementation of org.chromium.Mojo.ConnectChannel, exported over DBus.
+  // Takes a file descriptor and uses it to create a MessagePipe that is then
+  // hooked to a RemotePtr<mojo::ExternalServiceHost>.
+  void ConnectChannel(dbus::MethodCall* method_call,
+                      dbus::ExportedObject::ResponseSender sender);
+
+  void ExportMethods();
+  void InitializeDBus();
+  void TakeDBusServiceOwnership();
+
+  const std::string service_name_;
+  scoped_refptr<dbus::Bus> bus_;
+  dbus::ExportedObject* exported_object_;  // Owned by bus_;
+  scoped_ptr<mojo::common::ChannelInit> channel_init_;
+  DISALLOW_COPY_AND_ASSIGN(DBusExternalServiceBase);
+};
+
+template <class ServiceImpl>
+class DBusExternalService : public DBusExternalServiceBase,
+                            public mojo::ExternalService {
+ public:
+  explicit DBusExternalService(const std::string& service_name)
+      : DBusExternalServiceBase(service_name) {
+  }
+  virtual ~DBusExternalService() {}
+
+ protected:
+  virtual void Connect(ScopedExternalServiceHostHandle client_handle) OVERRIDE {
+    external_service_host_.reset(client_handle.Pass(), this, this);
+  }
+
+  virtual void Disconnect() OVERRIDE {
+    app_.reset();
+    external_service_host_.reset();
+  }
+
+ private:
+  virtual void Activate(mojo::ScopedMessagePipeHandle client_handle) OVERRIDE {
+    mojo::ScopedShellHandle shell_handle(
+        mojo::ShellHandle(client_handle.release().value()));
+    app_.reset(new mojo::Application(shell_handle.Pass()));
+    app_->AddServiceConnector(new mojo::ServiceConnector<ServiceImpl>());
+  }
+
+  mojo::RemotePtr<mojo::ExternalServiceHost> external_service_host_;
+  scoped_ptr<mojo::Application> app_;
+};
+
+}  // namespace mojo