Add a simple prototype "terminal" example.

examples/echo_terminal/main.cc

Index: examples/echo_terminal/main.cc
diff --git a/examples/echo_terminal/main.cc b/examples/echo_terminal/main.cc
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--- /dev/null
+++ b/examples/echo_terminal/main.cc
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+// Copyright 2015 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/bind.h"
+#include "base/bind_helpers.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "examples/echo_terminal/terminal_client.mojom.h"
+#include "mojo/application/application_runner_chromium.h"
+#include "mojo/common/weak_binding_set.h"
+#include "mojo/public/c/system/main.h"
+#include "mojo/public/cpp/application/application_connection.h"
+#include "mojo/public/cpp/application/application_delegate.h"
+#include "mojo/public/cpp/application/interface_factory.h"
+#include "services/files/file.mojom.h"
+#include "services/files/types.mojom.h"
+
+const uint32_t kMaxBytesToRead = 1000;
+
+// Owns itself.
+class TerminalEchoer : mojo::ErrorHandler {
+ public:
+  explicit TerminalEchoer(mojo::files::FilePtr terminal)
+      : terminal_(terminal.Pass()), last_bytes_read_size_(0) {}
+
+  void StartReading() {
+    // TODO(vtl): Are |offset| and |whence| correct?
+    terminal_->Read(
+        kMaxBytesToRead, 0, mojo::files::WHENCE_FROM_CURRENT,
+        base::Bind(&TerminalEchoer::OnRead, base::Unretained(this)));
+  }
+
+ private:
+  ~TerminalEchoer() override {}
+
+  // |mojo::ErrorHandler| implementation:
+  void OnConnectionError() override { delete this; }
+
+  // |Read()| callback:
+  void OnRead(mojo::files::Error error, mojo::Array<uint8_t> bytes_read) {
+    if (error) {
+      LOG(ERROR) << "Error: Read(): " << error;
+      delete this;
+      return;
+    }
+
+    if (!bytes_read) {
+      LOG(ERROR) << "Error: no bytes read (null)";
+      delete this;
+      return;
+    }
+
+    if (bytes_read.size() == 0 || bytes_read.size() > kMaxBytesToRead) {
+      LOG(ERROR) << "Error: invalid amount of bytes read: " << bytes_read.size()
+                 << " bytes";
+      delete this;
+      return;
+    }
+
+    // Save this, so that we can check in |OnWrite()|.
+    last_bytes_read_size_ = bytes_read.size();
+
+    // TODO(vtl): Are |offset| and |whence| correct?
+    terminal_->Write(
+        bytes_read.Pass(), 0, mojo::files::WHENCE_FROM_CURRENT,
+        base::Bind(&TerminalEchoer::OnWrite, base::Unretained(this)));
+  }
+
+  // |Write()| callback:
+  void OnWrite(mojo::files::Error error, uint32_t num_bytes_written) {
+    if (error) {
+      LOG(ERROR) << "Error: Write(): " << error;
+      delete this;
+      return;
+    }
+
+    if (num_bytes_written != last_bytes_read_size_) {
+      LOG(ERROR) << "Error: failed to write all bytes (last read: "
+                 << last_bytes_read_size_
+                 << " bytes; wrote: " << num_bytes_written << " bytes)";
+      delete this;
+      return;
+    }
+
+    StartReading();
+  }
+
+  mojo::files::FilePtr terminal_;
+  size_t last_bytes_read_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(TerminalEchoer);
+};
+
+class EchoTerminalApp
+    : public mojo::ApplicationDelegate,
+      public mojo::InterfaceFactory<mojo::terminal::TerminalClient>,
+      public mojo::terminal::TerminalClient {
+ public:
+  EchoTerminalApp() {}
+  ~EchoTerminalApp() override {}
+
+ private:
+  // |ApplicationDelegate| override:
+  bool ConfigureIncomingConnection(
+      mojo::ApplicationConnection* connection) override {
+    connection->AddService<mojo::terminal::TerminalClient>(this);
+    return true;
+  }
+
+  // |InterfaceFactory<mojo::terminal::TerminalClient>| implementation:
+  void Create(
+      mojo::ApplicationConnection* connection,
+      mojo::InterfaceRequest<mojo::terminal::TerminalClient> request) override {
+    terminal_clients_.AddBinding(this, request.Pass());
+  }
+
+  // |mojo::terminal::TerminalClient| implementation:
+  void ConnectToTerminal(mojo::files::FilePtr terminal) override {
+    DCHECK(terminal);
+    // The |TerminalEchoer| will own itself.
+    (new TerminalEchoer(terminal.Pass()))->StartReading();
+  }
+
+  mojo::WeakBindingSet<mojo::terminal::TerminalClient> terminal_clients_;
+
+  DISALLOW_COPY_AND_ASSIGN(EchoTerminalApp);
+};
+
+MojoResult MojoMain(MojoHandle shell_handle) {
+  mojo::ApplicationRunnerChromium runner(new EchoTerminalApp());
+  return runner.Run(shell_handle);
+}