mojo/edk/embedder/multiprocess_embedder_unittest.cc

// 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 "mojo/edk/embedder/multiprocess_embedder.h"

#include <string.h>

#include <memory>

#include "base/logging.h"
#include "mojo/edk/embedder/test_embedder.h"
#include "mojo/edk/platform/platform_pipe.h"
#include "mojo/edk/system/test/test_command_line.h"
#include "mojo/edk/system/test/test_io_thread.h"
#include "mojo/edk/system/test/timeouts.h"
#include "mojo/edk/test/multiprocess_test_helper.h"
#include "mojo/edk/test/scoped_ipc_support.h"
#include "mojo/edk/util/command_line.h"
#include "mojo/edk/util/ref_ptr.h"
#include "mojo/edk/util/waitable_event.h"
#include "mojo/public/c/system/handle.h"
#include "mojo/public/c/system/time.h"
#include "mojo/public/c/system/wait.h"
#include "mojo/public/cpp/system/handle.h"
#include "mojo/public/cpp/system/macros.h"
#include "mojo/public/cpp/system/message_pipe.h"
#include "mojo/public/cpp/system/wait.h"
#include "testing/gtest/include/gtest/gtest.h"

using mojo::platform::PlatformHandleWatcher;
using mojo::platform::PlatformPipe;
using mojo::platform::ScopedPlatformHandle;
using mojo::platform::TaskRunner;
using mojo::system::test::TestIOThread;
using mojo::util::ManualResetWaitableEvent;
using mojo::util::RefPtr;

namespace mojo {
namespace embedder {
namespace {

const MojoHandleSignals kSignalReadadableWritable =
    MOJO_HANDLE_SIGNAL_READABLE | MOJO_HANDLE_SIGNAL_WRITABLE;

const MojoHandleSignals kSignalAll = MOJO_HANDLE_SIGNAL_READABLE |
                                     MOJO_HANDLE_SIGNAL_WRITABLE |
                                     MOJO_HANDLE_SIGNAL_PEER_CLOSED;

const char kConnectionIdFlag[] = "test-connection-id";

class ScopedTestChannel {
 public:
  // Creates a channel, which lives on the I/O thread given to
  // |InitIPCSupport()|. After construction, |bootstrap_message_pipe()| gives
  // the Mojo handle for the bootstrap message pipe on this channel; it is up to
  // the caller to close this handle. Note: The I/O thread must outlive this
  // object (and its message loop must continue pumping messages while this
  // object is alive).
  explicit ScopedTestChannel(ScopedPlatformHandle platform_handle)
      : bootstrap_message_pipe_(MOJO_HANDLE_INVALID),
        channel_info_(nullptr),
        wait_on_shutdown_(true) {
    bootstrap_message_pipe_ = CreateChannel(platform_handle.Pass(),
                                            [this](ChannelInfo* channel_info) {
                                              CHECK(channel_info);
                                              CHECK(!channel_info_);
                                              channel_info_ = channel_info;
                                              event_.Signal();
                                            },
                                            nullptr)
                                  .release()
                                  .value();
    CHECK_NE(bootstrap_message_pipe_, MOJO_HANDLE_INVALID);
  }

  // Destructor: Shuts down the channel. (As noted above, for this to happen,
  // the I/O thread must be alive and pumping messages.)
  ~ScopedTestChannel() {
    // |WaitForChannelCreationCompletion()| must be called before destruction.
    CHECK(event_.IsSignaledForTest());
    event_.Reset();
    if (wait_on_shutdown_) {
      DestroyChannel(channel_info_, [this]() { event_.Signal(); }, nullptr);
      event_.Wait();
    } else {
      DestroyChannel(channel_info_, []() {}, nullptr);
    }
  }

  // Waits for channel creation to be completed.
  void WaitForChannelCreationCompletion() { event_.Wait(); }

  MojoHandle bootstrap_message_pipe() const { return bootstrap_message_pipe_; }

  // Call only after |WaitForChannelCreationCompletion()|. Use only to check
  // that it's not null.
  const ChannelInfo* channel_info() const { return channel_info_; }

  // Don't wait for the channel shutdown to finish on destruction. Used to
  // exercise races.
  void NoWaitOnShutdown() { wait_on_shutdown_ = false; }

 private:
  // Valid from creation until whenever it gets closed (by the "owner" of this
  // object).
  // Note: We don't want use the C++ wrappers here, since we want to test the
  // API at the lowest level.
  MojoHandle bootstrap_message_pipe_;

  // Set after channel creation has been completed (i.e., the callback to
  // |CreateChannel()| has been called). Also used in the destructor to wait for
  // |DestroyChannel()| completion.
  ManualResetWaitableEvent event_;

  // Valid after channel creation completion until destruction.
  ChannelInfo* channel_info_;

  // Whether the destructor should wait until the channel is destroyed.
  bool wait_on_shutdown_;

  MOJO_DISALLOW_COPY_AND_ASSIGN(ScopedTestChannel);
};

class MultiprocessEmbedderTest : public testing::Test {
 public:
  MultiprocessEmbedderTest() : test_io_thread_(TestIOThread::StartMode::AUTO) {}
  ~MultiprocessEmbedderTest() override {}

 protected:
  TestIOThread& test_io_thread() { return test_io_thread_; }
  const RefPtr<TaskRunner>& test_io_task_runner() {
    return test_io_thread_.task_runner();
  }
  PlatformHandleWatcher* test_io_watcher() {
    return test_io_thread_.platform_handle_watcher();
  }

 private:
  void SetUp() override { test::InitWithSimplePlatformSupport(); }

  void TearDown() override { EXPECT_TRUE(test::Shutdown()); }

  TestIOThread test_io_thread_;

  MOJO_DISALLOW_COPY_AND_ASSIGN(MultiprocessEmbedderTest);
};

TEST_F(MultiprocessEmbedderTest, ChannelsBasic) {
  mojo::test::ScopedIPCSupport ipc_support(test_io_task_runner().Clone(),
                                           test_io_watcher());

  PlatformPipe channel_pair;
  ScopedTestChannel server_channel(channel_pair.handle0.Pass());
  MojoHandle server_mp = server_channel.bootstrap_message_pipe();
  EXPECT_NE(server_mp, MOJO_HANDLE_INVALID);
  ScopedTestChannel client_channel(channel_pair.handle1.Pass());
  MojoHandle client_mp = client_channel.bootstrap_message_pipe();
  EXPECT_NE(client_mp, MOJO_HANDLE_INVALID);

  // We can write to a message pipe handle immediately.
  const char kHello[] = "hello";
  EXPECT_EQ(
      MOJO_RESULT_OK,
      MojoWriteMessage(server_mp, kHello, static_cast<uint32_t>(sizeof(kHello)),
                       nullptr, 0, MOJO_WRITE_MESSAGE_FLAG_NONE));

  // Now wait for the other side to become readable.
  MojoHandleSignalsState state;
  EXPECT_EQ(MOJO_RESULT_OK, MojoWait(client_mp, MOJO_HANDLE_SIGNAL_READABLE,
                                     MOJO_DEADLINE_INDEFINITE, &state));
  EXPECT_EQ(kSignalReadadableWritable, state.satisfied_signals);
  EXPECT_EQ(kSignalAll, state.satisfiable_signals);

  char buffer[1000] = {};
  uint32_t num_bytes = static_cast<uint32_t>(sizeof(buffer));
  EXPECT_EQ(MOJO_RESULT_OK,
            MojoReadMessage(client_mp, buffer, &num_bytes, nullptr, nullptr,
                            MOJO_READ_MESSAGE_FLAG_NONE));
  EXPECT_EQ(sizeof(kHello), num_bytes);
  EXPECT_STREQ(kHello, buffer);

  EXPECT_EQ(MOJO_RESULT_OK, MojoClose(server_mp));
  EXPECT_EQ(MOJO_RESULT_OK, MojoClose(client_mp));

  // By this point, these waits should basically be no-ops (since we've waited
  // for the client message pipe to become readable, which implies that both
  // the server and client channels were completely created).
  server_channel.WaitForChannelCreationCompletion();
  client_channel.WaitForChannelCreationCompletion();
  EXPECT_TRUE(server_channel.channel_info());
  EXPECT_TRUE(client_channel.channel_info());
}

TEST_F(MultiprocessEmbedderTest, ChannelsHandlePassing) {
  mojo::test::ScopedIPCSupport ipc_support(test_io_task_runner().Clone(),
                                           test_io_watcher());

  PlatformPipe channel_pair;
  ScopedTestChannel server_channel(channel_pair.handle0.Pass());
  MojoHandle server_mp = server_channel.bootstrap_message_pipe();
  EXPECT_NE(server_mp, MOJO_HANDLE_INVALID);
  ScopedTestChannel client_channel(channel_pair.handle1.Pass());
  MojoHandle client_mp = client_channel.bootstrap_message_pipe();
  EXPECT_NE(client_mp, MOJO_HANDLE_INVALID);

  MojoHandle h0, h1;
  EXPECT_EQ(MOJO_RESULT_OK, MojoCreateMessagePipe(nullptr, &h0, &h1));

  // Write a message to |h0| (attaching nothing).
  const char kHello[] = "hello";
  EXPECT_EQ(MOJO_RESULT_OK,
            MojoWriteMessage(h0, kHello, static_cast<uint32_t>(sizeof(kHello)),
                             nullptr, 0, MOJO_WRITE_MESSAGE_FLAG_NONE));

  // Write one message to |server_mp|, attaching |h1|.
  const char kWorld[] = "world!!!";
  EXPECT_EQ(
      MOJO_RESULT_OK,
      MojoWriteMessage(server_mp, kWorld, static_cast<uint32_t>(sizeof(kWorld)),
                       &h1, 1, MOJO_WRITE_MESSAGE_FLAG_NONE));
  h1 = MOJO_HANDLE_INVALID;

  // Write another message to |h0|.
  const char kFoo[] = "foo";
  EXPECT_EQ(MOJO_RESULT_OK,
            MojoWriteMessage(h0, kFoo, static_cast<uint32_t>(sizeof(kFoo)),
                             nullptr, 0, MOJO_WRITE_MESSAGE_FLAG_NONE));

  // Wait for |client_mp| to become readable.
  MojoHandleSignalsState state;
  EXPECT_EQ(MOJO_RESULT_OK, MojoWait(client_mp, MOJO_HANDLE_SIGNAL_READABLE,
                                     MOJO_DEADLINE_INDEFINITE, &state));
  EXPECT_EQ(kSignalReadadableWritable, state.satisfied_signals);
  EXPECT_EQ(kSignalAll, state.satisfiable_signals);

  // Read a message from |client_mp|.
  char buffer[1000] = {};
  uint32_t num_bytes = static_cast<uint32_t>(sizeof(buffer));
  MojoHandle handles[10] = {};
  uint32_t num_handles = MOJO_ARRAYSIZE(handles);
  EXPECT_EQ(MOJO_RESULT_OK,
            MojoReadMessage(client_mp, buffer, &num_bytes, handles,
                            &num_handles, MOJO_READ_MESSAGE_FLAG_NONE));
  EXPECT_EQ(sizeof(kWorld), num_bytes);
  EXPECT_STREQ(kWorld, buffer);
  EXPECT_EQ(1u, num_handles);
  EXPECT_NE(handles[0], MOJO_HANDLE_INVALID);
  h1 = handles[0];

  // Wait for |h1| to become readable.
  EXPECT_EQ(MOJO_RESULT_OK, MojoWait(h1, MOJO_HANDLE_SIGNAL_READABLE,
                                     MOJO_DEADLINE_INDEFINITE, &state));
  EXPECT_EQ(kSignalReadadableWritable, state.satisfied_signals);
  EXPECT_EQ(kSignalAll, state.satisfiable_signals);

  // Read a message from |h1|.
  memset(buffer, 0, sizeof(buffer));
  num_bytes = static_cast<uint32_t>(sizeof(buffer));
  memset(handles, 0, sizeof(handles));
  num_handles = MOJO_ARRAYSIZE(handles);
  EXPECT_EQ(MOJO_RESULT_OK,
            MojoReadMessage(h1, buffer, &num_bytes, handles, &num_handles,
                            MOJO_READ_MESSAGE_FLAG_NONE));
  EXPECT_EQ(sizeof(kHello), num_bytes);
  EXPECT_STREQ(kHello, buffer);
  EXPECT_EQ(0u, num_handles);

  // Wait for |h1| to become readable (again).
  EXPECT_EQ(MOJO_RESULT_OK, MojoWait(h1, MOJO_HANDLE_SIGNAL_READABLE,
                                     MOJO_DEADLINE_INDEFINITE, &state));
  EXPECT_EQ(kSignalReadadableWritable, state.satisfied_signals);
  EXPECT_EQ(kSignalAll, state.satisfiable_signals);

  // Read the second message from |h1|.
  memset(buffer, 0, sizeof(buffer));
  num_bytes = static_cast<uint32_t>(sizeof(buffer));
  EXPECT_EQ(MOJO_RESULT_OK,
            MojoReadMessage(h1, buffer, &num_bytes, nullptr, nullptr,
                            MOJO_READ_MESSAGE_FLAG_NONE));
  EXPECT_EQ(sizeof(kFoo), num_bytes);
  EXPECT_STREQ(kFoo, buffer);

  // Write a message to |h1|.
  const char kBarBaz[] = "barbaz";
  EXPECT_EQ(
      MOJO_RESULT_OK,
      MojoWriteMessage(h1, kBarBaz, static_cast<uint32_t>(sizeof(kBarBaz)),
                       nullptr, 0, MOJO_WRITE_MESSAGE_FLAG_NONE));

  // Wait for |h0| to become readable.
  EXPECT_EQ(MOJO_RESULT_OK, MojoWait(h0, MOJO_HANDLE_SIGNAL_READABLE,
                                     MOJO_DEADLINE_INDEFINITE, &state));
  EXPECT_EQ(kSignalReadadableWritable, state.satisfied_signals);
  EXPECT_EQ(kSignalAll, state.satisfiable_signals);

  // Read a message from |h0|.
  memset(buffer, 0, sizeof(buffer));
  num_bytes = static_cast<uint32_t>(sizeof(buffer));
  EXPECT_EQ(MOJO_RESULT_OK,
            MojoReadMessage(h0, buffer, &num_bytes, nullptr, nullptr,
                            MOJO_READ_MESSAGE_FLAG_NONE));
  EXPECT_EQ(sizeof(kBarBaz), num_bytes);
  EXPECT_STREQ(kBarBaz, buffer);

  EXPECT_EQ(MOJO_RESULT_OK, MojoClose(server_mp));
  EXPECT_EQ(MOJO_RESULT_OK, MojoClose(client_mp));
  EXPECT_EQ(MOJO_RESULT_OK, MojoClose(h0));
  EXPECT_EQ(MOJO_RESULT_OK, MojoClose(h1));

  server_channel.WaitForChannelCreationCompletion();
  client_channel.WaitForChannelCreationCompletion();
  EXPECT_TRUE(server_channel.channel_info());
  EXPECT_TRUE(client_channel.channel_info());
}

#if defined(OS_ANDROID)
// Android multi-process tests are not executing the new process. This is flaky.
// TODO(vtl): I'm guessing this is true of this test too?
#define MAYBE_MultiprocessMasterSlave DISABLED_MultiprocessMasterSlave
#else
#define MAYBE_MultiprocessMasterSlave MultiprocessMasterSlave
#endif  // defined(OS_ANDROID)
TEST_F(MultiprocessEmbedderTest, MAYBE_MultiprocessMasterSlave) {
  mojo::test::ScopedMasterIPCSupport ipc_support(test_io_task_runner().Clone(),
                                                 test_io_watcher());

  mojo::test::MultiprocessTestHelper multiprocess_test_helper;
  std::string connection_id;
  ManualResetWaitableEvent event;
  ChannelInfo* channel_info = nullptr;
  ScopedMessagePipeHandle mp = ConnectToSlave(
      nullptr, multiprocess_test_helper.server_platform_handle.Pass(),
      [&event]() { event.Signal(); }, nullptr, &connection_id, &channel_info);
  ASSERT_TRUE(mp.is_valid());
  EXPECT_TRUE(channel_info);
  ASSERT_FALSE(connection_id.empty());

  multiprocess_test_helper.StartChildWithExtraSwitch(
      "MultiprocessMasterSlave", kConnectionIdFlag, connection_id);

  // Send a message saying "hello".
  EXPECT_EQ(MOJO_RESULT_OK, WriteMessageRaw(mp.get(), "hello", 5, nullptr, 0,
                                            MOJO_WRITE_MESSAGE_FLAG_NONE));

  // Wait for a response.
  EXPECT_EQ(MOJO_RESULT_OK, Wait(mp.get(), MOJO_HANDLE_SIGNAL_READABLE,
                                 mojo::system::test::ActionTimeout(), nullptr));

  // The response message should say "world".
  char buffer[100];
  uint32_t num_bytes = static_cast<uint32_t>(sizeof(buffer));
  EXPECT_EQ(MOJO_RESULT_OK,
            ReadMessageRaw(mp.get(), buffer, &num_bytes, nullptr, nullptr,
                           MOJO_READ_MESSAGE_FLAG_NONE));
  EXPECT_EQ(5u, num_bytes);
  EXPECT_EQ(0, memcmp(buffer, "world", 5));

  mp.reset();

  EXPECT_TRUE(multiprocess_test_helper.WaitForChildTestShutdown());

  EXPECT_FALSE(event.WaitWithTimeout(mojo::system::test::ActionTimeout()));
  test_io_thread().PostTaskAndWait(
      [channel_info]() { DestroyChannelOnIOThread(channel_info); });
}

TEST_F(MultiprocessEmbedderTest, ChannelShutdownRace_MessagePipeClose) {
  const size_t kIterations = 1000;
  mojo::test::ScopedIPCSupport ipc_support(test_io_task_runner().Clone(),
                                           test_io_watcher());

  for (size_t i = 0; i < kIterations; i++) {
    PlatformPipe channel_pair;
    std::unique_ptr<ScopedTestChannel> server_channel(
        new ScopedTestChannel(channel_pair.handle0.Pass()));
    server_channel->WaitForChannelCreationCompletion();
    server_channel->NoWaitOnShutdown();

    MojoHandle server_mp = server_channel->bootstrap_message_pipe();
    EXPECT_NE(server_mp, MOJO_HANDLE_INVALID);

    // Race between channel shutdown and closing a message pipe. The message
    // pipe doesn't have to be the bootstrap pipe. It just has to be bound to
    // the channel.
    server_channel.reset();
    MojoClose(server_mp);
  }
}

MOJO_MULTIPROCESS_TEST_CHILD_TEST(MultiprocessMasterSlave) {
  ScopedPlatformHandle client_platform_handle =
      mojo::test::MultiprocessTestHelper::client_platform_handle.Pass();
  EXPECT_TRUE(client_platform_handle.is_valid());

  TestIOThread test_io_thread(TestIOThread::StartMode::AUTO);
  test::InitWithSimplePlatformSupport();

  {
    mojo::test::ScopedSlaveIPCSupport ipc_support(
        test_io_thread.task_runner().Clone(),
        test_io_thread.platform_handle_watcher(),
        client_platform_handle.Pass());

    std::string connection_id;
    ASSERT_TRUE(mojo::system::test::GetTestCommandLine()->GetOptionValue(
        kConnectionIdFlag, &connection_id));
    ASSERT_FALSE(connection_id.empty());
    ManualResetWaitableEvent event;
    ChannelInfo* channel_info = nullptr;
    ScopedMessagePipeHandle mp = ConnectToMaster(
        connection_id, [&event]() { event.Signal(); }, nullptr, &channel_info);
    ASSERT_TRUE(mp.is_valid());
    EXPECT_TRUE(channel_info);

    // Wait for the master to send us a message.
    EXPECT_EQ(MOJO_RESULT_OK,
              Wait(mp.get(), MOJO_HANDLE_SIGNAL_READABLE,
                   mojo::system::test::ActionTimeout(), nullptr));

    // It should say "hello".
    char buffer[100];
    uint32_t num_bytes = static_cast<uint32_t>(sizeof(buffer));
    EXPECT_EQ(MOJO_RESULT_OK,
              ReadMessageRaw(mp.get(), buffer, &num_bytes, nullptr, nullptr,
                             MOJO_READ_MESSAGE_FLAG_NONE));
    EXPECT_EQ(5u, num_bytes);
    EXPECT_EQ(0, memcmp(buffer, "hello", 5));

    // In response send a message saying "world".
    EXPECT_EQ(MOJO_RESULT_OK, WriteMessageRaw(mp.get(), "world", 5, nullptr, 0,
                                              MOJO_WRITE_MESSAGE_FLAG_NONE));

    mp.reset();

    EXPECT_FALSE(event.WaitWithTimeout(mojo::system::test::ActionTimeout()));
    test_io_thread.PostTaskAndWait(
        [channel_info]() { DestroyChannelOnIOThread(channel_info); });
  }

  EXPECT_TRUE(test::Shutdown());
}

// The sequence of messages sent is:
//       server_mp   client_mp   mp0         mp1         mp2         mp3
//   1.  "hello"
//   2.              "world!"
//   3.                          "FOO"
//   4.  "Bar"+mp1
//   5.  (close)
//   6.              (close)
//   7.                                                              "baz"
//   8.                                                              (closed)
//   9.                                      "quux"+mp2
//  10.                          (close)
//  11.                                      (wait/cl.)
//  12.                                                  (wait/cl.)

#if defined(OS_ANDROID)
// Android multi-process tests are not executing the new process. This is flaky.
#define MAYBE_MultiprocessChannels DISABLED_MultiprocessChannels
#else
#define MAYBE_MultiprocessChannels MultiprocessChannels
#endif  // defined(OS_ANDROID)
TEST_F(MultiprocessEmbedderTest, MAYBE_MultiprocessChannels) {
  // TODO(vtl): This should eventually initialize a master process instead,
  // probably.
  mojo::test::ScopedIPCSupport ipc_support(test_io_task_runner().Clone(),
                                           test_io_watcher());

  mojo::test::MultiprocessTestHelper multiprocess_test_helper;
  multiprocess_test_helper.StartChild("MultiprocessChannelsClient");

  {
    ScopedTestChannel server_channel(
        multiprocess_test_helper.server_platform_handle.Pass());
    MojoHandle server_mp = server_channel.bootstrap_message_pipe();
    EXPECT_NE(server_mp, MOJO_HANDLE_INVALID);
    server_channel.WaitForChannelCreationCompletion();
    EXPECT_TRUE(server_channel.channel_info());

    // 1. Write a message to |server_mp| (attaching nothing).
    const char kHello[] = "hello";
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoWriteMessage(server_mp, kHello,
                               static_cast<uint32_t>(sizeof(kHello)), nullptr,
                               0, MOJO_WRITE_MESSAGE_FLAG_NONE));

    // TODO(vtl): If the scope were ended immediately here (maybe after closing
    // |server_mp|), we die with a fatal error in |Channel::HandleLocalError()|.

    // 2. Read a message from |server_mp|.
    MojoHandleSignalsState state;
    EXPECT_EQ(MOJO_RESULT_OK, MojoWait(server_mp, MOJO_HANDLE_SIGNAL_READABLE,
                                       MOJO_DEADLINE_INDEFINITE, &state));
    EXPECT_EQ(kSignalReadadableWritable, state.satisfied_signals);
    EXPECT_EQ(kSignalAll, state.satisfiable_signals);

    char buffer[1000] = {};
    uint32_t num_bytes = static_cast<uint32_t>(sizeof(buffer));
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoReadMessage(server_mp, buffer, &num_bytes, nullptr, nullptr,
                              MOJO_READ_MESSAGE_FLAG_NONE));
    const char kWorld[] = "world!";
    EXPECT_EQ(sizeof(kWorld), num_bytes);
    EXPECT_STREQ(kWorld, buffer);

    // Create a new message pipe (endpoints |mp0| and |mp1|).
    MojoHandle mp0, mp1;
    EXPECT_EQ(MOJO_RESULT_OK, MojoCreateMessagePipe(nullptr, &mp0, &mp1));

    // 3. Write something to |mp0|.
    const char kFoo[] = "FOO";
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoWriteMessage(mp0, kFoo, static_cast<uint32_t>(sizeof(kFoo)),
                               nullptr, 0, MOJO_WRITE_MESSAGE_FLAG_NONE));

    // 4. Write a message to |server_mp|, attaching |mp1|.
    const char kBar[] = "Bar";
    EXPECT_EQ(
        MOJO_RESULT_OK,
        MojoWriteMessage(server_mp, kBar, static_cast<uint32_t>(sizeof(kBar)),
                         &mp1, 1, MOJO_WRITE_MESSAGE_FLAG_NONE));
    mp1 = MOJO_HANDLE_INVALID;

    // 5. Close |server_mp|.
    EXPECT_EQ(MOJO_RESULT_OK, MojoClose(server_mp));

    // 9. Read a message from |mp0|, which should have |mp2| attached.
    EXPECT_EQ(MOJO_RESULT_OK, MojoWait(mp0, MOJO_HANDLE_SIGNAL_READABLE,
                                       MOJO_DEADLINE_INDEFINITE, &state));
    EXPECT_EQ(kSignalReadadableWritable, state.satisfied_signals);
    EXPECT_EQ(kSignalAll, state.satisfiable_signals);

    memset(buffer, 0, sizeof(buffer));
    num_bytes = static_cast<uint32_t>(sizeof(buffer));
    MojoHandle mp2 = MOJO_HANDLE_INVALID;
    uint32_t num_handles = 1;
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoReadMessage(mp0, buffer, &num_bytes, &mp2, &num_handles,
                              MOJO_READ_MESSAGE_FLAG_NONE));
    const char kQuux[] = "quux";
    EXPECT_EQ(sizeof(kQuux), num_bytes);
    EXPECT_STREQ(kQuux, buffer);
    EXPECT_EQ(1u, num_handles);
    EXPECT_NE(mp2, MOJO_HANDLE_INVALID);

    // 7. Read a message from |mp2|.
    EXPECT_EQ(MOJO_RESULT_OK, MojoWait(mp2, MOJO_HANDLE_SIGNAL_READABLE,
                                       MOJO_DEADLINE_INDEFINITE, &state));
    EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE | MOJO_HANDLE_SIGNAL_PEER_CLOSED,
              state.satisfied_signals);
    EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE | MOJO_HANDLE_SIGNAL_PEER_CLOSED,
              state.satisfiable_signals);

    memset(buffer, 0, sizeof(buffer));
    num_bytes = static_cast<uint32_t>(sizeof(buffer));
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoReadMessage(mp2, buffer, &num_bytes, nullptr, nullptr,
                              MOJO_READ_MESSAGE_FLAG_NONE));
    const char kBaz[] = "baz";
    EXPECT_EQ(sizeof(kBaz), num_bytes);
    EXPECT_STREQ(kBaz, buffer);

    // 10. Close |mp0|.
    EXPECT_EQ(MOJO_RESULT_OK, MojoClose(mp0));

// 12. Wait on |mp2| (which should eventually fail) and then close it.
// TODO(vtl): crbug.com/351768
#if 0
    EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION,
              MojoWait(mp2, MOJO_HANDLE_SIGNAL_READABLE,
                       MOJO_DEADLINE_INDEFINITE,
                       &state));
    EXPECT_EQ(MOJO_HANDLE_SIGNAL_NONE, state.satisfied_signals);
    EXPECT_EQ(MOJO_HANDLE_SIGNAL_NONE, state.satisfiable_signals);
#endif
    EXPECT_EQ(MOJO_RESULT_OK, MojoClose(mp2));
  }

  EXPECT_TRUE(multiprocess_test_helper.WaitForChildTestShutdown());
}

MOJO_MULTIPROCESS_TEST_CHILD_TEST(MultiprocessChannelsClient) {
  ScopedPlatformHandle client_platform_handle =
      mojo::test::MultiprocessTestHelper::client_platform_handle.Pass();
  EXPECT_TRUE(client_platform_handle.is_valid());

  TestIOThread test_io_thread(TestIOThread::StartMode::AUTO);
  test::InitWithSimplePlatformSupport();

  {
    // TODO(vtl): This should eventually initialize a slave process instead,
    // probably.
    mojo::test::ScopedIPCSupport ipc_support(
        test_io_thread.task_runner().Clone(),
        test_io_thread.platform_handle_watcher());

    ScopedTestChannel client_channel(client_platform_handle.Pass());
    MojoHandle client_mp = client_channel.bootstrap_message_pipe();
    EXPECT_NE(client_mp, MOJO_HANDLE_INVALID);
    client_channel.WaitForChannelCreationCompletion();
    CHECK(client_channel.channel_info() != nullptr);

    // 1. Read the first message from |client_mp|.
    MojoHandleSignalsState state;
    EXPECT_EQ(MOJO_RESULT_OK, MojoWait(client_mp, MOJO_HANDLE_SIGNAL_READABLE,
                                       MOJO_DEADLINE_INDEFINITE, &state));
    EXPECT_EQ(kSignalReadadableWritable, state.satisfied_signals);
    EXPECT_EQ(kSignalAll, state.satisfiable_signals);

    char buffer[1000] = {};
    uint32_t num_bytes = static_cast<uint32_t>(sizeof(buffer));
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoReadMessage(client_mp, buffer, &num_bytes, nullptr, nullptr,
                              MOJO_READ_MESSAGE_FLAG_NONE));
    const char kHello[] = "hello";
    EXPECT_EQ(sizeof(kHello), num_bytes);
    EXPECT_STREQ(kHello, buffer);

    // 2. Write a message to |client_mp| (attaching nothing).
    const char kWorld[] = "world!";
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoWriteMessage(client_mp, kWorld,
                               static_cast<uint32_t>(sizeof(kWorld)), nullptr,
                               0, MOJO_WRITE_MESSAGE_FLAG_NONE));

    // 4. Read a message from |client_mp|, which should have |mp1| attached.
    EXPECT_EQ(MOJO_RESULT_OK, MojoWait(client_mp, MOJO_HANDLE_SIGNAL_READABLE,
                                       MOJO_DEADLINE_INDEFINITE, &state));
    // The other end of the handle may or may not be closed at this point, so we
    // can't test MOJO_HANDLE_SIGNAL_WRITABLE or MOJO_HANDLE_SIGNAL_PEER_CLOSED.
    EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE,
              state.satisfied_signals & MOJO_HANDLE_SIGNAL_READABLE);
    EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE,
              state.satisfiable_signals & MOJO_HANDLE_SIGNAL_READABLE);
    // TODO(vtl): If the scope were to end here (and |client_mp| closed), we'd
    // die (again due to |Channel::HandleLocalError()|).
    memset(buffer, 0, sizeof(buffer));
    num_bytes = static_cast<uint32_t>(sizeof(buffer));
    MojoHandle mp1 = MOJO_HANDLE_INVALID;
    uint32_t num_handles = 1;
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoReadMessage(client_mp, buffer, &num_bytes, &mp1, &num_handles,
                              MOJO_READ_MESSAGE_FLAG_NONE));
    const char kBar[] = "Bar";
    EXPECT_EQ(sizeof(kBar), num_bytes);
    EXPECT_STREQ(kBar, buffer);
    EXPECT_EQ(1u, num_handles);
    EXPECT_NE(mp1, MOJO_HANDLE_INVALID);
    // TODO(vtl): If the scope were to end here (and the two handles closed),
    // we'd die due to |Channel::RunRemoteMessagePipeEndpoint()| not handling
    // write errors (assuming the parent had closed the pipe).

    // 6. Close |client_mp|.
    EXPECT_EQ(MOJO_RESULT_OK, MojoClose(client_mp));

    // Create a new message pipe (endpoints |mp2| and |mp3|).
    MojoHandle mp2, mp3;
    EXPECT_EQ(MOJO_RESULT_OK, MojoCreateMessagePipe(nullptr, &mp2, &mp3));

    // 7. Write a message to |mp3|.
    const char kBaz[] = "baz";
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoWriteMessage(mp3, kBaz, static_cast<uint32_t>(sizeof(kBaz)),
                               nullptr, 0, MOJO_WRITE_MESSAGE_FLAG_NONE));

    // 8. Close |mp3|.
    EXPECT_EQ(MOJO_RESULT_OK, MojoClose(mp3));

    // 9. Write a message to |mp1|, attaching |mp2|.
    const char kQuux[] = "quux";
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoWriteMessage(mp1, kQuux, static_cast<uint32_t>(sizeof(kQuux)),
                               &mp2, 1, MOJO_WRITE_MESSAGE_FLAG_NONE));
    mp2 = MOJO_HANDLE_INVALID;

    // 3. Read a message from |mp1|.
    EXPECT_EQ(MOJO_RESULT_OK, MojoWait(mp1, MOJO_HANDLE_SIGNAL_READABLE,
                                       MOJO_DEADLINE_INDEFINITE, &state));
    EXPECT_EQ(kSignalReadadableWritable, state.satisfied_signals);
    EXPECT_EQ(kSignalAll, state.satisfiable_signals);

    memset(buffer, 0, sizeof(buffer));
    num_bytes = static_cast<uint32_t>(sizeof(buffer));
    EXPECT_EQ(MOJO_RESULT_OK,
              MojoReadMessage(mp1, buffer, &num_bytes, nullptr, nullptr,
                              MOJO_READ_MESSAGE_FLAG_NONE));
    const char kFoo[] = "FOO";
    EXPECT_EQ(sizeof(kFoo), num_bytes);
    EXPECT_STREQ(kFoo, buffer);

    // 11. Wait on |mp1| (which should eventually fail) and then close it.
    EXPECT_EQ(MOJO_RESULT_FAILED_PRECONDITION,
              MojoWait(mp1, MOJO_HANDLE_SIGNAL_READABLE,
                       MOJO_DEADLINE_INDEFINITE, &state));
    EXPECT_EQ(MOJO_HANDLE_SIGNAL_PEER_CLOSED, state.satisfied_signals);
    EXPECT_EQ(MOJO_HANDLE_SIGNAL_PEER_CLOSED, state.satisfiable_signals);
    EXPECT_EQ(MOJO_RESULT_OK, MojoClose(mp1));
  }

  EXPECT_TRUE(test::Shutdown());
}

// TODO(vtl): Test immediate write & close.
// TODO(vtl): Test broken-connection cases.

}  // namespace
}  // namespace embedder
}  // namespace mojo