zircon/system/utest/fidl/encoding_tests.cc

// Copyright 2017 The Fuchsia 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 <lib/fidl/coding.h>
#include <lib/zx/eventpair.h>
#include <limits.h>
#include <stddef.h>
#include <unittest/unittest.h>
#include <zircon/syscalls.h>

#include <memory>

#include "fidl_coded_types.h"
#include "fidl_structs.h"

namespace fidl {
namespace {

// Some notes:
//
// - All tests of out-of-line bounded allocation overruns need to have
//   another big out-of-line allocation following it. This
//   distinguishes "the buffer is too small" from "the bits on the
//   wire asked for more than the type allowed".

// TODO(kulakowski) Change the tests to check for more specific error
// values, once those are settled.

constexpr zx_handle_t dummy_handle_0 = static_cast<zx_handle_t>(23);
constexpr zx_handle_t dummy_handle_1 = static_cast<zx_handle_t>(24);
constexpr zx_handle_t dummy_handle_2 = static_cast<zx_handle_t>(25);
constexpr zx_handle_t dummy_handle_3 = static_cast<zx_handle_t>(26);
constexpr zx_handle_t dummy_handle_4 = static_cast<zx_handle_t>(27);
constexpr zx_handle_t dummy_handle_5 = static_cast<zx_handle_t>(28);
constexpr zx_handle_t dummy_handle_6 = static_cast<zx_handle_t>(29);
constexpr zx_handle_t dummy_handle_7 = static_cast<zx_handle_t>(30);
constexpr zx_handle_t dummy_handle_8 = static_cast<zx_handle_t>(31);
constexpr zx_handle_t dummy_handle_9 = static_cast<zx_handle_t>(32);
constexpr zx_handle_t dummy_handle_10 = static_cast<zx_handle_t>(33);
constexpr zx_handle_t dummy_handle_11 = static_cast<zx_handle_t>(34);
constexpr zx_handle_t dummy_handle_12 = static_cast<zx_handle_t>(35);
constexpr zx_handle_t dummy_handle_13 = static_cast<zx_handle_t>(36);
constexpr zx_handle_t dummy_handle_14 = static_cast<zx_handle_t>(37);
constexpr zx_handle_t dummy_handle_15 = static_cast<zx_handle_t>(38);
constexpr zx_handle_t dummy_handle_16 = static_cast<zx_handle_t>(39);
constexpr zx_handle_t dummy_handle_17 = static_cast<zx_handle_t>(40);
constexpr zx_handle_t dummy_handle_18 = static_cast<zx_handle_t>(41);
constexpr zx_handle_t dummy_handle_19 = static_cast<zx_handle_t>(42);
constexpr zx_handle_t dummy_handle_20 = static_cast<zx_handle_t>(43);
constexpr zx_handle_t dummy_handle_21 = static_cast<zx_handle_t>(44);
constexpr zx_handle_t dummy_handle_22 = static_cast<zx_handle_t>(45);
constexpr zx_handle_t dummy_handle_23 = static_cast<zx_handle_t>(46);
constexpr zx_handle_t dummy_handle_24 = static_cast<zx_handle_t>(47);
constexpr zx_handle_t dummy_handle_25 = static_cast<zx_handle_t>(48);
constexpr zx_handle_t dummy_handle_26 = static_cast<zx_handle_t>(49);
constexpr zx_handle_t dummy_handle_27 = static_cast<zx_handle_t>(50);
constexpr zx_handle_t dummy_handle_28 = static_cast<zx_handle_t>(51);
constexpr zx_handle_t dummy_handle_29 = static_cast<zx_handle_t>(52);

// All sizes in fidl encoding tables are 32 bits. The fidl compiler
// normally enforces this. Check manually in manual tests.
template <typename T, size_t N>
uint32_t ArrayCount(T const (&array)[N]) {
  static_assert(N < UINT32_MAX, "Array is too large!");
  return N;
}

template <typename T, size_t N>
uint32_t ArraySize(T const (&array)[N]) {
  static_assert(sizeof(array) < UINT32_MAX, "Array is too large!");
  return sizeof(array);
}

// Check if the other end of the eventpair is valid
bool IsPeerValid(const zx::unowned_eventpair handle) {
  zx_signals_t observed_signals = {};
  switch (handle->wait_one(ZX_EVENTPAIR_PEER_CLOSED, zx::deadline_after(zx::msec(1)),
                           &observed_signals)) {
    case ZX_ERR_TIMED_OUT:
      // timeout implies peer-closed was not observed
      return true;
    case ZX_OK:
      return (observed_signals & ZX_EVENTPAIR_PEER_CLOSED) == 0;
    default:
      return false;
  }
}

bool encode_null_encode_parameters() {
  BEGIN_TEST;

  zx_handle_t handles[1] = {};

  // Null message type.
  {
    nonnullable_handle_message_layout message;
    const char* error = nullptr;
    uint32_t actual_handles = 0u;
    auto status = fidl_encode(nullptr, &message, sizeof(nonnullable_handle_message_layout), handles,
                              ArrayCount(handles), &actual_handles, &error);
    EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
    EXPECT_NONNULL(error);
  }

  // Null message.
  {
    const char* error = nullptr;
    uint32_t actual_handles = 0u;
    auto status = fidl_encode(&nonnullable_handle_message_type, nullptr,
                              sizeof(nonnullable_handle_message_layout), handles,
                              ArrayCount(handles), &actual_handles, &error);
    EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
    EXPECT_NONNULL(error);
  }

  // Null handles, for a message that has a handle.
  {
    nonnullable_handle_message_layout message;
    const char* error = nullptr;
    uint32_t actual_handles = 0u;
    auto status =
        fidl_encode(&nonnullable_handle_message_type, &message,
                    sizeof(nonnullable_handle_message_layout), nullptr, 0, &actual_handles, &error);
    EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
    EXPECT_NONNULL(error);
  }

  // Null handles but positive handle count.
  {
    nonnullable_handle_message_layout message;
    const char* error = nullptr;
    uint32_t actual_handles = 0u;
    auto status =
        fidl_encode(&nonnullable_handle_message_type, &message,
                    sizeof(nonnullable_handle_message_layout), nullptr, 1, &actual_handles, &error);
    EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
    EXPECT_NONNULL(error);
  }

  // A null actual handle count pointer.
  {
    nonnullable_handle_message_layout message;
    const char* error = nullptr;
    auto status = fidl_encode(&nonnullable_handle_message_type, &message,
                              sizeof(nonnullable_handle_message_layout), handles,
                              ArrayCount(handles), nullptr, &error);
    EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
    EXPECT_NONNULL(error);
  }

  // A null error string pointer is ok, though.
  {
    uint32_t actual_handles = 0u;
    auto status = fidl_encode(nullptr, nullptr, 0u, nullptr, 0u, &actual_handles, nullptr);
    EXPECT_NE(status, ZX_OK);
  }

  // A null error is also ok in success cases.
  {
    nonnullable_handle_message_layout message = {};
    message.inline_struct.handle = dummy_handle_0;

    uint32_t actual_handles = 0u;
    auto status = fidl_encode(&nonnullable_handle_message_type, &message,
                              sizeof(nonnullable_handle_message_layout), handles,
                              ArrayCount(handles), &actual_handles, nullptr);
    EXPECT_EQ(status, ZX_OK);
    EXPECT_EQ(actual_handles, 1u);
    EXPECT_EQ(handles[0], dummy_handle_0);
    EXPECT_EQ(message.inline_struct.handle, FIDL_HANDLE_PRESENT);
  }

  END_TEST;
}

bool encode_single_present_handle_unaligned_error() {
  BEGIN_TEST;

  // Test a short, unaligned version of nonnullable message
  // handle. All fidl message objects should be 8 byte aligned.
  //
  // We use a byte array rather than fidl_message_header_t to avoid
  // aligning to 8 bytes.
  struct unaligned_nonnullable_handle_inline_data {
    uint8_t header[sizeof(fidl_message_header_t)];
    zx_handle_t handle;
  };
  struct unaligned_nonnullable_handle_message_layout {
    unaligned_nonnullable_handle_inline_data inline_struct;
  };

  unaligned_nonnullable_handle_message_layout message = {};
  message.inline_struct.handle = dummy_handle_0;

  zx_handle_t handles[1] = {};

  // Encoding the unaligned version of the struct should fail.
  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nonnullable_handle_message_type, &message, sizeof(message), handles,
                            ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nonnullable_string_unaligned_error() {
  BEGIN_TEST;

  unbounded_nonnullable_string_message_layout message = {};
  message.inline_struct.string = fidl_string_t{6, &message.data[0]};
  memcpy(message.data, "hello!", 6);

  // Copy the message to unaligned storage one byte off from true alignment
  unbounded_nonnullable_string_message_layout message_storage[2];
  uint8_t* unaligned_ptr = reinterpret_cast<uint8_t*>(&message_storage[0]) + 1;
  memcpy(unaligned_ptr, &message, sizeof(message));
  auto unaligned_msg =
      reinterpret_cast<unbounded_nonnullable_string_message_layout*>(unaligned_ptr);
  unaligned_msg->inline_struct.string.data = &unaligned_msg->data[0];

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nonnullable_string_message_type, unaligned_msg,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);
  ASSERT_STR_STR(error, "must be aligned to FIDL_ALIGNMENT");

  END_TEST;
}

bool encode_single_present_handle() {
  BEGIN_TEST;

  nonnullable_handle_message_layout message = {};
  message.inline_struct.handle = dummy_handle_0;

  zx_handle_t handles[1] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nonnullable_handle_message_type, &message, sizeof(message), handles,
                            ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 1u);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(message.inline_struct.handle, FIDL_HANDLE_PRESENT);

  END_TEST;
}

bool encode_single_present_handle_zero_trailing_padding() {
  BEGIN_TEST;

  // Initialize a buffer with garbage value of 0xAA.
  constexpr size_t kBufferSize = sizeof(nonnullable_handle_message_layout);
  uint8_t buffer[kBufferSize];
  memset(buffer, 0xAA, sizeof(buffer));

  nonnullable_handle_message_layout* message = new (&buffer[0]) nonnullable_handle_message_layout;
  message->inline_struct.handle = dummy_handle_0;

  EXPECT_EQ(buffer[kBufferSize - 4], 0xAA);
  EXPECT_EQ(buffer[kBufferSize - 3], 0xAA);
  EXPECT_EQ(buffer[kBufferSize - 2], 0xAA);
  EXPECT_EQ(buffer[kBufferSize - 1], 0xAA);

  zx_handle_t handles[1] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nonnullable_handle_message_type, message, kBufferSize, handles,
                            ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 1u);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(message->inline_struct.handle, FIDL_HANDLE_PRESENT);

  // Last 4 bytes are trailing padding after the handle and before the end of the structure.
  // Despite being initialized to 0xAA, these should be set to zero by the encoder.
  EXPECT_EQ(buffer[kBufferSize - 4], 0);
  EXPECT_EQ(buffer[kBufferSize - 3], 0);
  EXPECT_EQ(buffer[kBufferSize - 2], 0);
  EXPECT_EQ(buffer[kBufferSize - 1], 0);

  END_TEST;
}

bool encode_too_many_bytes_specified_should_close_handles() {
  BEGIN_TEST;

  zx::eventpair ep0, ep1;
  ASSERT_EQ(zx::eventpair::create(0, &ep0, &ep1), ZX_OK);

  constexpr size_t kSizeTooBig = sizeof(nonnullable_handle_message_layout) * 2;
  std::unique_ptr<uint8_t[]> buffer = std::make_unique<uint8_t[]>(kSizeTooBig);
  nonnullable_handle_message_layout& message =
      *reinterpret_cast<nonnullable_handle_message_layout*>(buffer.get());
  message.inline_struct.handle = ep0.get();

  ASSERT_TRUE(IsPeerValid(zx::unowned_eventpair(ep1)));

  zx_handle_t handles[1] = {};
  const char* error = nullptr;
  uint32_t actual_handles = 1234;
  auto status = fidl_encode(&nonnullable_handle_message_type, &message, kSizeTooBig, handles,
                            ArrayCount(handles), &actual_handles, &error);

  ASSERT_EQ(status, ZX_ERR_INVALID_ARGS);
  ASSERT_NONNULL(error);
  ASSERT_EQ(actual_handles, 0);
  ASSERT_EQ(message.inline_struct.handle, FIDL_HANDLE_PRESENT);
  ASSERT_EQ(handles[0], ep0.get());
  ASSERT_FALSE(IsPeerValid(zx::unowned_eventpair(ep1)));

  // When the test succeeds, |ep0| is closed by the encoder.
  zx_handle_t unused = ep0.release();
  (void)unused;

  END_TEST;
}

bool encode_multiple_present_handles() {
  BEGIN_TEST;

  multiple_nonnullable_handles_message_layout message = {};
  message.inline_struct.handle_0 = dummy_handle_0;
  message.inline_struct.handle_1 = dummy_handle_1;
  message.inline_struct.handle_2 = dummy_handle_2;

  zx_handle_t handles[3] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&multiple_nonnullable_handles_message_type, &message, sizeof(message),
                            handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 3u);
  EXPECT_EQ(message.inline_struct.data_0, 0u);
  EXPECT_EQ(message.inline_struct.handle_0, FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.data_1, 0u);
  EXPECT_EQ(message.inline_struct.handle_1, FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handle_2, FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.data_2, 0u);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);

  END_TEST;
}

bool encode_single_absent_handle() {
  BEGIN_TEST;

  nullable_handle_message_layout message = {};
  message.inline_struct.handle = ZX_HANDLE_INVALID;

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nullable_handle_message_type, &message, sizeof(message), nullptr, 0,
                            &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(message.inline_struct.handle, FIDL_HANDLE_ABSENT);

  END_TEST;
}

bool encode_multiple_absent_handles() {
  BEGIN_TEST;

  multiple_nullable_handles_message_layout message = {};
  message.inline_struct.handle_0 = ZX_HANDLE_INVALID;
  message.inline_struct.handle_1 = ZX_HANDLE_INVALID;
  message.inline_struct.handle_2 = ZX_HANDLE_INVALID;

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&multiple_nullable_handles_message_type, &message, sizeof(message),
                            nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(message.inline_struct.data_0, 0u);
  EXPECT_EQ(message.inline_struct.handle_0, FIDL_HANDLE_ABSENT);
  EXPECT_EQ(message.inline_struct.data_1, 0u);
  EXPECT_EQ(message.inline_struct.handle_1, FIDL_HANDLE_ABSENT);
  EXPECT_EQ(message.inline_struct.handle_2, FIDL_HANDLE_ABSENT);
  EXPECT_EQ(message.inline_struct.data_2, 0u);

  END_TEST;
}

bool encode_array_of_present_handles() {
  BEGIN_TEST;

  array_of_nonnullable_handles_message_layout message = {};
  message.inline_struct.handles[0] = dummy_handle_0;
  message.inline_struct.handles[1] = dummy_handle_1;
  message.inline_struct.handles[2] = dummy_handle_2;
  message.inline_struct.handles[3] = dummy_handle_3;

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&array_of_nonnullable_handles_message_type, &message, sizeof(message),
                            handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 4u);
  EXPECT_EQ(message.inline_struct.handles[0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[3], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);

  END_TEST;
}

bool encode_array_of_present_handles_error_closes_handles() {
  BEGIN_TEST;

  array_of_nonnullable_handles_message_layout message = {};
  zx_handle_t handle_pairs[4][2];
  // Use eventpairs so that we can know for sure that handles were closed by fidl_encode.
  for (uint32_t i = 0; i < ArrayCount(handle_pairs); ++i) {
    ASSERT_EQ(zx_eventpair_create(0u, &handle_pairs[i][0], &handle_pairs[i][1]), ZX_OK);
  }
  message.inline_struct.handles[0] = handle_pairs[0][0];
  message.inline_struct.handles[1] = handle_pairs[1][0];
  message.inline_struct.handles[2] = handle_pairs[2][0];
  message.inline_struct.handles[3] = handle_pairs[3][0];

  zx_handle_t output_handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&array_of_nonnullable_handles_message_type, &message, sizeof(message),
                            output_handles,
                            // -2 makes this invalid.
                            ArrayCount(message.inline_struct.handles) - 2, &actual_handles, &error);
  // Should fail because we we pass in a max_handles < the actual number of handles.
  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_EQ(actual_handles, 0);
  // All handles should be closed, those before the error was encountered and those after.
  for (uint32_t i = 0; i < ArrayCount(handle_pairs); ++i) {
    zx_signals_t observed_signals;
    EXPECT_EQ(zx_object_wait_one(handle_pairs[i][1], ZX_EVENTPAIR_PEER_CLOSED,
                                 1,  // deadline shouldn't matter, should return immediately.
                                 &observed_signals),
              ZX_OK);
    EXPECT_EQ(observed_signals & ZX_EVENTPAIR_PEER_CLOSED, ZX_EVENTPAIR_PEER_CLOSED);
    EXPECT_EQ(zx_handle_close(handle_pairs[i][1]), ZX_OK);  // [i][0] was closed by fidl_encode.
  }

  END_TEST;
}

bool encode_array_of_nullable_handles() {
  BEGIN_TEST;

  array_of_nullable_handles_message_layout message = {};
  message.inline_struct.handles[0] = dummy_handle_0;
  message.inline_struct.handles[1] = ZX_HANDLE_INVALID;
  message.inline_struct.handles[2] = dummy_handle_1;
  message.inline_struct.handles[3] = ZX_HANDLE_INVALID;
  message.inline_struct.handles[4] = dummy_handle_2;

  zx_handle_t handles[3] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&array_of_nullable_handles_message_type, &message, sizeof(message),
                            handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 3u);
  EXPECT_EQ(message.inline_struct.handles[0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[1], FIDL_HANDLE_ABSENT);
  EXPECT_EQ(message.inline_struct.handles[2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[3], FIDL_HANDLE_ABSENT);
  EXPECT_EQ(message.inline_struct.handles[4], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);

  END_TEST;
}

bool encode_array_of_nullable_handles_with_insufficient_handles_error() {
  BEGIN_TEST;

  array_of_nullable_handles_message_layout message = {};
  message.inline_struct.handles[0] = dummy_handle_0;
  message.inline_struct.handles[1] = ZX_HANDLE_INVALID;
  message.inline_struct.handles[2] = dummy_handle_1;
  message.inline_struct.handles[3] = ZX_HANDLE_INVALID;
  message.inline_struct.handles[4] = dummy_handle_2;

  zx_handle_t handles[2] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&array_of_nullable_handles_message_type, &message, sizeof(message),
                            handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_array_of_array_of_present_handles() {
  BEGIN_TEST;

  array_of_array_of_nonnullable_handles_message_layout message = {};
  message.inline_struct.handles[0][0] = dummy_handle_0;
  message.inline_struct.handles[0][1] = dummy_handle_1;
  message.inline_struct.handles[0][2] = dummy_handle_2;
  message.inline_struct.handles[0][3] = dummy_handle_3;
  message.inline_struct.handles[1][0] = dummy_handle_4;
  message.inline_struct.handles[1][1] = dummy_handle_5;
  message.inline_struct.handles[1][2] = dummy_handle_6;
  message.inline_struct.handles[1][3] = dummy_handle_7;
  message.inline_struct.handles[2][0] = dummy_handle_8;
  message.inline_struct.handles[2][1] = dummy_handle_9;
  message.inline_struct.handles[2][2] = dummy_handle_10;
  message.inline_struct.handles[2][3] = dummy_handle_11;

  zx_handle_t handles[12] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&array_of_array_of_nonnullable_handles_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 12u);
  EXPECT_EQ(message.inline_struct.handles[0][0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[0][1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[0][2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[0][3], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[1][0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[1][1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[1][2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[1][3], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[2][0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[2][1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[2][2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.handles[2][3], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);
  EXPECT_EQ(handles[4], dummy_handle_4);
  EXPECT_EQ(handles[5], dummy_handle_5);
  EXPECT_EQ(handles[6], dummy_handle_6);
  EXPECT_EQ(handles[7], dummy_handle_7);
  EXPECT_EQ(handles[8], dummy_handle_8);
  EXPECT_EQ(handles[9], dummy_handle_9);
  EXPECT_EQ(handles[10], dummy_handle_10);
  EXPECT_EQ(handles[11], dummy_handle_11);

  END_TEST;
}

bool encode_out_of_line_array_of_nonnullable_handles() {
  BEGIN_TEST;

  out_of_line_array_of_nonnullable_handles_message_layout message = {};
  message.inline_struct.maybe_array = &message.data;
  message.data.handles[0] = dummy_handle_0;
  message.data.handles[1] = dummy_handle_1;
  message.data.handles[2] = dummy_handle_2;
  message.data.handles[3] = dummy_handle_3;

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&out_of_line_array_of_nonnullable_handles_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 4u);

  auto array_ptr = reinterpret_cast<uint64_t>(message.inline_struct.maybe_array);
  EXPECT_EQ(array_ptr, FIDL_ALLOC_PRESENT);
  EXPECT_EQ(message.data.handles[0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.data.handles[1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.data.handles[2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.data.handles[3], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);

  END_TEST;
}

bool encode_present_nonnullable_string() {
  BEGIN_TEST;

  unbounded_nonnullable_string_message_layout message = {};
  message.inline_struct.string = fidl_string_t{6, &message.data[0]};
  memcpy(message.data, "hello!", 6);

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nonnullable_string_message_type, &message, sizeof(message),
                            nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.string.data), FIDL_ALLOC_PRESENT);
  EXPECT_EQ(message.inline_struct.string.size, 6);
  EXPECT_EQ(message.data[0], 'h');
  EXPECT_EQ(message.data[1], 'e');
  EXPECT_EQ(message.data[2], 'l');
  EXPECT_EQ(message.data[3], 'l');
  EXPECT_EQ(message.data[4], 'o');
  EXPECT_EQ(message.data[5], '!');

  END_TEST;
}

bool encode_present_nullable_string() {
  BEGIN_TEST;

  unbounded_nullable_string_message_layout message = {};
  message.inline_struct.string = fidl_string_t{6, &message.data[0]};
  memcpy(message.data, "hello!", 6);

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nullable_string_message_type, &message, sizeof(message),
                            nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(message.inline_struct.string.size, 6);
  EXPECT_EQ(message.data[0], 'h');
  EXPECT_EQ(message.data[1], 'e');
  EXPECT_EQ(message.data[2], 'l');
  EXPECT_EQ(message.data[3], 'l');
  EXPECT_EQ(message.data[4], 'o');
  EXPECT_EQ(message.data[5], '!');

  END_TEST;
}

bool encode_multiple_present_nullable_string() {
  BEGIN_TEST;

  // Among other things, this test ensures we handle out-of-line
  // alignment to FIDL_ALIGNMENT (i.e., 8) bytes correctly.
  multiple_nullable_strings_message_layout message;
  message.inline_struct.string = fidl_string_t{6, &message.data[0]};
  message.inline_struct.string2 = fidl_string_t{8, &message.data2[0]};
  memcpy(message.data, "hello ", 6);
  memcpy(message.data2, "world!!!", 8);

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&multiple_nullable_strings_message_type, &message, sizeof(message),
                            nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(message.inline_struct.string.size, 6);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.string.data), FIDL_ALLOC_PRESENT);
  EXPECT_EQ(message.data[0], 'h');
  EXPECT_EQ(message.data[1], 'e');
  EXPECT_EQ(message.data[2], 'l');
  EXPECT_EQ(message.data[3], 'l');
  EXPECT_EQ(message.data[4], 'o');
  EXPECT_EQ(message.data[5], ' ');
  EXPECT_EQ(message.inline_struct.string2.size, 8);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.string2.data), FIDL_ALLOC_PRESENT);
  EXPECT_EQ(message.data2[0], 'w');
  EXPECT_EQ(message.data2[1], 'o');
  EXPECT_EQ(message.data2[2], 'r');
  EXPECT_EQ(message.data2[3], 'l');
  EXPECT_EQ(message.data2[4], 'd');
  EXPECT_EQ(message.data2[5], '!');
  EXPECT_EQ(message.data2[6], '!');
  EXPECT_EQ(message.data2[7], '!');

  END_TEST;
}

bool encode_absent_nonnullable_string_error() {
  BEGIN_TEST;

  unbounded_nonnullable_string_message_layout message = {};
  message.inline_struct.string = fidl_string_t{0u, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nonnullable_string_message_type, &message, sizeof(message),
                            nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_absent_nullable_string() {
  BEGIN_TEST;

  unbounded_nullable_string_message_layout message = {};
  message.inline_struct.string = fidl_string_t{0u, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nullable_string_message_type, &message,
                            sizeof(message.inline_struct), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.string.data), FIDL_ALLOC_ABSENT);

  END_TEST;
}

bool encode_present_nonnullable_bounded_string() {
  BEGIN_TEST;

  bounded_32_nonnullable_string_message_layout message = {};
  message.inline_struct.string = fidl_string_t{6, &message.data[0]};
  memcpy(message.data, "hello!", 6);

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nonnullable_string_message_type, &message, sizeof(message),
                            nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(message.inline_struct.string.size, 6);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.string.data), FIDL_ALLOC_PRESENT);
  EXPECT_EQ(message.data[0], 'h');
  EXPECT_EQ(message.data[1], 'e');
  EXPECT_EQ(message.data[2], 'l');
  EXPECT_EQ(message.data[3], 'l');
  EXPECT_EQ(message.data[4], 'o');
  EXPECT_EQ(message.data[5], '!');

  END_TEST;
}

bool encode_present_nullable_bounded_string() {
  BEGIN_TEST;

  bounded_32_nullable_string_message_layout message = {};
  message.inline_struct.string = fidl_string_t{6, &message.data[0]};
  memcpy(message.data, "hello!", 6);

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nullable_string_message_type, &message, sizeof(message),
                            nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(message.inline_struct.string.size, 6);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.string.data), FIDL_ALLOC_PRESENT);
  EXPECT_EQ(message.data[0], 'h');
  EXPECT_EQ(message.data[1], 'e');
  EXPECT_EQ(message.data[2], 'l');
  EXPECT_EQ(message.data[3], 'l');
  EXPECT_EQ(message.data[4], 'o');
  EXPECT_EQ(message.data[5], '!');

  END_TEST;
}

bool encode_absent_nonnullable_bounded_string_error() {
  BEGIN_TEST;

  bounded_32_nonnullable_string_message_layout message = {};
  message.inline_struct.string = fidl_string_t{6, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nonnullable_string_message_type, &message, sizeof(message),
                            nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.string.data), FIDL_ALLOC_ABSENT);

  END_TEST;
}

bool encode_absent_nullable_bounded_string() {
  BEGIN_TEST;

  bounded_32_nullable_string_message_layout message = {};
  message.inline_struct.string = fidl_string_t{6, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nullable_string_message_type, &message,
                            sizeof(message.inline_struct), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nonnullable_bounded_string_short_error() {
  BEGIN_TEST;

  multiple_short_nonnullable_strings_message_layout message = {};
  message.inline_struct.string = fidl_string_t{6, &message.data[0]};
  message.inline_struct.string2 = fidl_string_t{6, &message.data2[0]};
  memcpy(message.data, "hello!", 6);
  memcpy(message.data2, "hello!", 6);

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&multiple_short_nonnullable_strings_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nullable_bounded_string_short_error() {
  BEGIN_TEST;

  multiple_short_nullable_strings_message_layout message = {};
  message.inline_struct.string = fidl_string_t{6, &message.data[0]};
  message.inline_struct.string2 = fidl_string_t{6, &message.data2[0]};
  memcpy(message.data, "hello!", 6);
  memcpy(message.data2, "hello!", 6);

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&multiple_short_nullable_strings_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_vector_with_huge_count() {
  BEGIN_TEST;

  unbounded_nonnullable_vector_of_uint32_message_layout message = {};
  // (2^30 + 4) * 4 (4 == sizeof(uint32_t)) overflows to 16 when stored as uint32_t.
  // We want 16 because it happens to be the actual size of the vector data in the message,
  // so we can trigger the overflow without triggering the "tried to claim too many bytes" or
  // "didn't use all the bytes in the message" errors.
  message.inline_struct.vector = fidl_vector_t{(1ull << 30) + 4, &message.uint32[0]};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nonnullable_vector_of_uint32_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);
  const char expected_error_msg[] = "integer overflow calculating vector size";
  EXPECT_STR_EQ(expected_error_msg, error, "wrong error msg");
  EXPECT_EQ(actual_handles, 0u);

  END_TEST;
}

bool encode_present_nonnullable_vector_of_handles() {
  BEGIN_TEST;

  unbounded_nonnullable_vector_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.handles[0]};
  message.handles[0] = dummy_handle_0;
  message.handles[1] = dummy_handle_1;
  message.handles[2] = dummy_handle_2;
  message.handles[3] = dummy_handle_3;

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nonnullable_vector_of_handles_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 4u);

  auto message_handles = reinterpret_cast<uint64_t>(message.inline_struct.vector.data);
  EXPECT_EQ(message_handles, FIDL_ALLOC_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);
  EXPECT_EQ(message.handles[0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[3], FIDL_HANDLE_PRESENT);

  END_TEST;
}

bool encode_present_nullable_vector_of_handles() {
  BEGIN_TEST;

  unbounded_nullable_vector_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.handles[0]};
  message.handles[0] = dummy_handle_0;
  message.handles[1] = dummy_handle_1;
  message.handles[2] = dummy_handle_2;
  message.handles[3] = dummy_handle_3;

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nullable_vector_of_handles_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 4u);

  auto message_handles = reinterpret_cast<uint64_t>(message.inline_struct.vector.data);
  EXPECT_EQ(message_handles, FIDL_ALLOC_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);
  EXPECT_EQ(message.handles[0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[3], FIDL_HANDLE_PRESENT);

  END_TEST;
}

bool encode_absent_nonnullable_vector_of_handles_error() {
  BEGIN_TEST;

  unbounded_nonnullable_vector_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, nullptr};

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nonnullable_vector_of_handles_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_absent_nullable_vector_of_handles() {
  BEGIN_TEST;

  unbounded_nullable_vector_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nullable_vector_of_handles_message_type, &message,
                            sizeof(message.inline_struct), nullptr, 0u, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nonnullable_bounded_vector_of_handles() {
  BEGIN_TEST;

  bounded_32_nonnullable_vector_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.handles[0]};
  message.handles[0] = dummy_handle_0;
  message.handles[1] = dummy_handle_1;
  message.handles[2] = dummy_handle_2;
  message.handles[3] = dummy_handle_3;

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nonnullable_vector_of_handles_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 4u);

  auto message_handles = reinterpret_cast<uint64_t>(message.inline_struct.vector.data);
  EXPECT_EQ(message_handles, FIDL_ALLOC_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);
  EXPECT_EQ(message.handles[0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[3], FIDL_HANDLE_PRESENT);

  END_TEST;
}

bool encode_present_nullable_bounded_vector_of_handles() {
  BEGIN_TEST;

  bounded_32_nullable_vector_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.handles[0]};
  message.handles[0] = dummy_handle_0;
  message.handles[1] = dummy_handle_1;
  message.handles[2] = dummy_handle_2;
  message.handles[3] = dummy_handle_3;

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nullable_vector_of_handles_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 4u);

  auto message_handles = reinterpret_cast<uint64_t>(message.inline_struct.vector.data);
  EXPECT_EQ(message_handles, FIDL_ALLOC_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);
  EXPECT_EQ(message.handles[0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[2], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.handles[3], FIDL_HANDLE_PRESENT);

  END_TEST;
}

bool encode_absent_nonnullable_bounded_vector_of_handles() {
  BEGIN_TEST;

  bounded_32_nonnullable_vector_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nonnullable_vector_of_handles_message_type, &message,
                            sizeof(message), nullptr, 0u, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_absent_nullable_bounded_vector_of_handles() {
  BEGIN_TEST;

  bounded_32_nullable_vector_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nullable_vector_of_handles_message_type, &message,
                            sizeof(message.inline_struct), nullptr, 0u, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nonnullable_bounded_vector_of_handles_short_error() {
  BEGIN_TEST;

  multiple_nonnullable_vectors_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.handles[0]};
  message.inline_struct.vector2 = fidl_vector_t{4, &message.handles2[0]};
  message.handles[0] = dummy_handle_0;
  message.handles[1] = dummy_handle_1;
  message.handles[2] = dummy_handle_2;
  message.handles[3] = dummy_handle_3;
  message.handles2[0] = dummy_handle_4;
  message.handles2[1] = dummy_handle_5;
  message.handles2[2] = dummy_handle_6;
  message.handles2[3] = dummy_handle_7;

  zx_handle_t handles[8] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&multiple_nonnullable_vectors_of_handles_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nullable_bounded_vector_of_handles_short_error() {
  BEGIN_TEST;

  multiple_nullable_vectors_of_handles_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.handles[0]};
  message.inline_struct.vector2 = fidl_vector_t{4, &message.handles2[0]};
  message.handles[0] = dummy_handle_0;
  message.handles[1] = dummy_handle_1;
  message.handles[2] = dummy_handle_2;
  message.handles[3] = dummy_handle_3;
  message.handles2[0] = dummy_handle_4;
  message.handles2[1] = dummy_handle_5;
  message.handles2[2] = dummy_handle_6;
  message.handles2[3] = dummy_handle_7;

  zx_handle_t handles[8] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&multiple_nullable_vectors_of_handles_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nonnullable_vector_of_uint32() {
  BEGIN_TEST;

  unbounded_nonnullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.uint32[0]};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nonnullable_vector_of_uint32_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);

  auto message_uint32 = reinterpret_cast<uint64_t>(message.inline_struct.vector.data);
  EXPECT_EQ(message_uint32, FIDL_ALLOC_PRESENT);

  END_TEST;
}

bool encode_present_nullable_vector_of_uint32() {
  BEGIN_TEST;

  unbounded_nullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.uint32[0]};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nullable_vector_of_uint32_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);

  auto message_uint32 = reinterpret_cast<uint64_t>(message.inline_struct.vector.data);
  EXPECT_EQ(message_uint32, FIDL_ALLOC_PRESENT);

  END_TEST;
}

bool encode_absent_nonnullable_vector_of_uint32_error() {
  BEGIN_TEST;

  unbounded_nonnullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nonnullable_vector_of_uint32_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_absent_and_empty_nonnullable_vector_of_uint32_error() {
  BEGIN_TEST;

  unbounded_nonnullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{0, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nonnullable_vector_of_uint32_message_type, &message,
                            sizeof(message.inline_struct), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_absent_nullable_vector_of_uint32() {
  BEGIN_TEST;

  unbounded_nullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{0, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nullable_vector_of_uint32_message_type, &message,
                            sizeof(message.inline_struct), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error);

  auto message_uint32 = reinterpret_cast<uint64_t>(message.inline_struct.vector.data);
  EXPECT_EQ(message_uint32, FIDL_ALLOC_ABSENT);

  END_TEST;
}

bool encode_absent_nullable_vector_of_uint32_non_zero_length_error() {
  BEGIN_TEST;

  unbounded_nullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&unbounded_nullable_vector_of_uint32_message_type, &message,
                            sizeof(message.inline_struct), nullptr, 0u, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nonnullable_bounded_vector_of_uint32() {
  BEGIN_TEST;

  bounded_32_nonnullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.uint32[0]};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nonnullable_vector_of_uint32_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);

  auto message_uint32 = reinterpret_cast<uint64_t>(message.inline_struct.vector.data);
  EXPECT_EQ(message_uint32, FIDL_ALLOC_PRESENT);

  END_TEST;
}

bool encode_present_nullable_bounded_vector_of_uint32() {
  BEGIN_TEST;

  bounded_32_nullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.uint32[0]};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nullable_vector_of_uint32_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);

  auto message_uint32 = reinterpret_cast<uint64_t>(message.inline_struct.vector.data);
  EXPECT_EQ(message_uint32, FIDL_ALLOC_PRESENT);

  END_TEST;
}

bool encode_absent_nonnullable_bounded_vector_of_uint32() {
  BEGIN_TEST;

  bounded_32_nonnullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nonnullable_vector_of_uint32_message_type, &message,
                            sizeof(message), nullptr, 0u, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_absent_nullable_bounded_vector_of_uint32() {
  BEGIN_TEST;

  bounded_32_nullable_vector_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, nullptr};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&bounded_32_nullable_vector_of_uint32_message_type, &message,
                            sizeof(message.inline_struct), nullptr, 0u, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nonnullable_bounded_vector_of_uint32_short_error() {
  BEGIN_TEST;

  multiple_nonnullable_vectors_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.uint32[0]};
  message.inline_struct.vector2 = fidl_vector_t{4, &message.uint32_2[0]};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&multiple_nonnullable_vectors_of_uint32_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_present_nullable_bounded_vector_of_uint32_short_error() {
  BEGIN_TEST;

  multiple_nullable_vectors_of_uint32_message_layout message = {};
  message.inline_struct.vector = fidl_vector_t{4, &message.uint32[0]};
  message.inline_struct.vector2 = fidl_vector_t{4, &message.uint32_2[0]};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&multiple_nullable_vectors_of_uint32_message_type, &message,
                            sizeof(message), nullptr, 0, &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_bad_tagged_union_error() {
  BEGIN_TEST;

  nonnullable_handle_union_message_layout message = {};
  message.inline_struct.data.tag = 52u;
  message.inline_struct.data.handle = dummy_handle_0;

  zx_handle_t handles[1] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nonnullable_handle_union_message_type, &message, sizeof(message),
                            handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);

  END_TEST;
}

bool encode_single_armed_present_nonnullable_union() {
  BEGIN_TEST;

  nonnullable_handle_union_message_layout message = {};
  message.inline_struct.data.tag = nonnullable_handle_union_kHandle;
  message.inline_struct.data.handle = dummy_handle_0;

  zx_handle_t handles[1] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nonnullable_handle_union_message_type, &message, sizeof(message),
                            handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 1u);
  EXPECT_EQ(message.inline_struct.data.tag, nonnullable_handle_union_kHandle);
  EXPECT_EQ(message.inline_struct.data.handle, FIDL_HANDLE_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);

  END_TEST;
}

bool encode_many_armed_present_nonnullable_union() {
  BEGIN_TEST;

  array_of_nonnullable_handles_union_message_layout message = {};
  message.inline_struct.data.tag = array_of_nonnullable_handles_union_kArrayOfArrayOfHandles;
  message.inline_struct.data.array_of_array_of_handles[0][0] = dummy_handle_0;
  message.inline_struct.data.array_of_array_of_handles[0][1] = dummy_handle_1;
  message.inline_struct.data.array_of_array_of_handles[1][0] = dummy_handle_2;
  message.inline_struct.data.array_of_array_of_handles[1][1] = dummy_handle_3;

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&array_of_nonnullable_handles_union_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 4u);
  EXPECT_EQ(message.inline_struct.data.tag,
            array_of_nonnullable_handles_union_kArrayOfArrayOfHandles);
  EXPECT_EQ(message.inline_struct.data.array_of_array_of_handles[0][0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.data.array_of_array_of_handles[0][1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.data.array_of_array_of_handles[1][0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.data.array_of_array_of_handles[1][1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);

  END_TEST;
}

bool encode_many_armed_present_nonnullable_union_zero_trailing_padding() {
  BEGIN_TEST;

  // Initialize a buffer with garbage value of 0xAA.
  constexpr size_t kBufferSize = sizeof(array_of_nonnullable_handles_union_message_layout);
  uint8_t buffer[kBufferSize];
  memset(buffer, 0xAA, sizeof(buffer));

  array_of_nonnullable_handles_union_message_layout* message =
      new (&buffer[0]) array_of_nonnullable_handles_union_message_layout;

  message->inline_struct.data.tag = array_of_nonnullable_handles_union_kHandle;
  message->inline_struct.data.handle = dummy_handle_0;

  // 4 bytes tag + 16 bytes largest variant + 4 bytes padding = 24
  constexpr size_t kUnionSize = 24;
  static_assert(sizeof(message->inline_struct.data) == kUnionSize);
  // The union comes after the 16 byte message header.
  constexpr size_t kUnionOffset = 16;
  ASSERT_EQ(reinterpret_cast<uint8_t*>(&message->inline_struct.data) -
                reinterpret_cast<uint8_t*>(message),
            kUnionOffset);
  // 4 bytes tag
  constexpr size_t kHandleOffset = 4;
  ASSERT_EQ(reinterpret_cast<uint8_t*>(&message->inline_struct.data.handle) -
                reinterpret_cast<uint8_t*>(&message->inline_struct.data),
            kHandleOffset);
  for (size_t i = kHandleOffset + sizeof(zx_handle_t); i < kUnionSize; i++) {
    EXPECT_EQ(buffer[kUnionOffset + i], 0xAA);
  }

  zx_handle_t handles[1] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&array_of_nonnullable_handles_union_message_type, message, kBufferSize,
                            handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 1u);
  EXPECT_EQ(message->inline_struct.data.tag, array_of_nonnullable_handles_union_kHandle);
  EXPECT_EQ(message->inline_struct.data.handle, FIDL_HANDLE_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);

  // Validate that padding bytes have been cleared
  for (size_t i = kHandleOffset + sizeof(zx_handle_t); i < kUnionSize; i++) {
    EXPECT_EQ(buffer[kUnionOffset + i], 0);
  }

  END_TEST;
}

bool encode_single_armed_present_nullable_union() {
  BEGIN_TEST;

  nonnullable_handle_union_ptr_message_layout message = {};
  message.inline_struct.data = &message.data;
  message.data.tag = nonnullable_handle_union_kHandle;
  message.data.handle = dummy_handle_0;

  zx_handle_t handles[1] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nonnullable_handle_union_ptr_message_type, &message, sizeof(message),
                            handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 1u);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.data), FIDL_ALLOC_PRESENT);
  EXPECT_EQ(message.data.tag, nonnullable_handle_union_kHandle);
  EXPECT_EQ(message.data.handle, FIDL_HANDLE_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);

  END_TEST;
}

bool encode_many_armed_present_nullable_union() {
  BEGIN_TEST;

  array_of_nonnullable_handles_union_ptr_message_layout message = {};
  message.inline_struct.data = &message.data;
  message.data.tag = array_of_nonnullable_handles_union_kArrayOfArrayOfHandles;
  message.data.array_of_array_of_handles[0][0] = dummy_handle_0;
  message.data.array_of_array_of_handles[0][1] = dummy_handle_1;
  message.data.array_of_array_of_handles[1][0] = dummy_handle_2;
  message.data.array_of_array_of_handles[1][1] = dummy_handle_3;

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&array_of_nonnullable_handles_union_ptr_message_type, &message,
                            sizeof(message), handles, ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 4u);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.data), FIDL_ALLOC_PRESENT);
  EXPECT_EQ(message.data.tag, array_of_nonnullable_handles_union_kArrayOfArrayOfHandles);
  EXPECT_EQ(message.data.array_of_array_of_handles[0][0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.data.array_of_array_of_handles[0][1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.data.array_of_array_of_handles[1][0], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.data.array_of_array_of_handles[1][1], FIDL_HANDLE_PRESENT);
  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);

  END_TEST;
}

bool encode_single_armed_absent_nullable_union() {
  BEGIN_TEST;

  nonnullable_handle_union_ptr_message_layout message = {};
  message.inline_struct.data = nullptr;

  zx_handle_t handles[1] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nonnullable_handle_union_ptr_message_type, &message,
                            sizeof(message.inline_struct), handles, ArrayCount(handles),
                            &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.data), FIDL_ALLOC_ABSENT);

  END_TEST;
}

bool encode_many_armed_absent_nullable_union() {
  BEGIN_TEST;

  array_of_nonnullable_handles_union_ptr_message_layout message = {};
  message.inline_struct.data = nullptr;

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&array_of_nonnullable_handles_union_ptr_message_type, &message,
                            sizeof(message.inline_struct), nullptr, 0u, &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);
  EXPECT_EQ(actual_handles, 0u);
  EXPECT_EQ(reinterpret_cast<uint64_t>(message.inline_struct.data), FIDL_ALLOC_ABSENT);

  END_TEST;
}

bool encode_nested_nonnullable_structs() {
  BEGIN_TEST;

  // Note the traversal order! l1 -> l3 -> l2 -> l0
  nested_structs_message_layout message = {};
  message.inline_struct.l0.l1.handle_1 = dummy_handle_0;
  message.inline_struct.l0.l1.l2.l3.handle_3 = dummy_handle_1;
  message.inline_struct.l0.l1.l2.handle_2 = dummy_handle_2;
  message.inline_struct.l0.handle_0 = dummy_handle_3;

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nested_structs_message_type, &message, sizeof(message), handles,
                            ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);

  EXPECT_EQ(message.inline_struct.l0.l1.handle_1, FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.l0.l1.l2.l3.handle_3, FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.l0.l1.l2.handle_2, FIDL_HANDLE_PRESENT);
  EXPECT_EQ(message.inline_struct.l0.handle_0, FIDL_HANDLE_PRESENT);

  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);

  END_TEST;
}

bool encode_nested_nonnullable_structs_zero_padding() {
  BEGIN_TEST;

  // Initialize a buffer with garbage value of 0xAA.
  constexpr size_t kBufferSize = sizeof(nested_structs_message_layout);
  uint8_t buffer[kBufferSize];
  memset(buffer, 0xAA, sizeof(buffer));

  nested_structs_message_layout* message = new (&buffer[0]) nested_structs_message_layout;
  message->inline_struct.l0.l1.handle_1 = dummy_handle_0;
  message->inline_struct.l0.l1.l2.l3.handle_3 = dummy_handle_1;
  message->inline_struct.l0.l1.l2.handle_2 = dummy_handle_2;
  message->inline_struct.l0.handle_0 = dummy_handle_3;

  // Wire-format:
  // message
  // - 16 bytes header
  // + struct_level_0  -------------  offset 16 = 4 * 4
  //   - uint64_t
  //   + struct_level_1  -----------  offset 24 = 4 * 6
  //     - zx_handle_t
  //     - (4 bytes padding)  ------  offset 28 = 4 * 7
  //     + struct_level_2  ---------  offset 32 = 4 * 8
  //       - uint64_t
  //       + struct_level_3  -------  offset 40 = 4 * 10
  //         - uint32_t
  //         - zx_handle_t
  //       - zx_handle_t
  //       - (4 bytes padding)  ----  offset 52 = 4 * 13
  //     - uint64_t
  //   - zx_handle_t
  //   - (4 bytes padding)  --------  offset 68 = 4 * 17
  static_assert(sizeof(nested_structs_message_layout) == 68 + 4);

  // Read padding bytes, four bytes at a time.
  uint32_t* dwords = reinterpret_cast<uint32_t*>(&buffer[0]);
  EXPECT_EQ(dwords[7], 0xAAAAAAAA);
  EXPECT_EQ(dwords[13], 0xAAAAAAAA);
  EXPECT_EQ(dwords[17], 0xAAAAAAAA);

  zx_handle_t handles[4] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nested_structs_message_type, message, kBufferSize, handles,
                            ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);

  // Validate that all padding bytes are zero, by checking four bytes at a time.
  EXPECT_EQ(dwords[7], 0);
  EXPECT_EQ(dwords[13], 0);
  EXPECT_EQ(dwords[17], 0);

  END_TEST;
}

bool encode_nested_nullable_structs() {
  BEGIN_TEST;

  nested_struct_ptrs_message_layout message = {};
  message.inline_struct.l0_inline.l1_inline.l2_present = &message.in_in_out_2;
  message.inline_struct.l0_inline.l1_inline.l2_present->l3_present = &message.in_in_out_out_3;
  message.inline_struct.l0_inline.l1_inline.l2_inline.l3_present = &message.in_in_in_out_3;
  message.inline_struct.l0_inline.l1_present = &message.in_out_1;
  message.inline_struct.l0_inline.l1_present->l2_present = &message.in_out_out_2;
  message.inline_struct.l0_inline.l1_present->l2_present->l3_present = &message.in_out_out_out_3;
  message.inline_struct.l0_inline.l1_present->l2_inline.l3_present = &message.in_out_in_out_3;
  message.inline_struct.l0_present = &message.out_0;
  message.inline_struct.l0_present->l1_inline.l2_present = &message.out_in_out_2;
  message.inline_struct.l0_present->l1_inline.l2_present->l3_present = &message.out_in_out_out_3;
  message.inline_struct.l0_present->l1_inline.l2_inline.l3_present = &message.out_in_in_out_3;
  message.inline_struct.l0_present->l1_present = &message.out_out_1;
  message.inline_struct.l0_present->l1_present->l2_present = &message.out_out_out_2;
  message.inline_struct.l0_present->l1_present->l2_present->l3_present = &message.out_out_out_out_3;
  message.inline_struct.l0_present->l1_present->l2_inline.l3_present = &message.out_out_in_out_3;

  // 0 inline
  //     1 inline
  //         handle
  message.inline_struct.l0_inline.l1_inline.handle_1 = dummy_handle_0;
  //         2 out of line
  //             3 out of line
  message.in_in_out_out_3.handle_3 = dummy_handle_1;
  //             3 inline
  message.in_in_out_2.l3_inline.handle_3 = dummy_handle_2;
  //             handle
  message.in_in_out_2.handle_2 = dummy_handle_3;
  //         2 inline
  //             3 out of line
  message.in_in_in_out_3.handle_3 = dummy_handle_4;
  //             3 inline
  message.inline_struct.l0_inline.l1_inline.l2_inline.l3_inline.handle_3 = dummy_handle_5;
  //             handle
  message.inline_struct.l0_inline.l1_inline.l2_inline.handle_2 = dummy_handle_6;
  //     handle
  message.inline_struct.l0_inline.handle_0 = dummy_handle_7;
  //     1 out of line
  //         handle
  message.in_out_1.handle_1 = dummy_handle_8;
  //         2 out of line
  //             3 out of line
  message.in_out_out_out_3.handle_3 = dummy_handle_9;
  //             3 inline
  message.in_out_out_2.l3_inline.handle_3 = dummy_handle_10;
  //             handle
  message.in_out_out_2.handle_2 = dummy_handle_11;
  //         2 inline
  //             3 out of line
  message.in_out_in_out_3.handle_3 = dummy_handle_12;
  //             3 inline
  message.in_out_1.l2_inline.l3_inline.handle_3 = dummy_handle_13;
  //             handle
  message.in_out_1.l2_inline.handle_2 = dummy_handle_14;
  // 0 out of line
  //     1 inline
  //         handle
  message.out_0.l1_inline.handle_1 = dummy_handle_15;
  //         2 out of line
  //             3 out of line
  message.out_in_out_out_3.handle_3 = dummy_handle_16;
  //             3 inline
  message.out_in_out_2.l3_inline.handle_3 = dummy_handle_17;
  //             handle
  message.out_in_out_2.handle_2 = dummy_handle_18;
  //         2 inline
  //             3 out of line
  message.out_in_in_out_3.handle_3 = dummy_handle_19;
  //             3 inline
  message.out_0.l1_inline.l2_inline.l3_inline.handle_3 = dummy_handle_20;
  //             handle
  message.out_0.l1_inline.l2_inline.handle_2 = dummy_handle_21;
  //     handle
  message.out_0.handle_0 = dummy_handle_22;
  //     1 out of line
  //         handle
  message.out_out_1.handle_1 = dummy_handle_23;
  //         2 out of line
  //             3 out of line
  message.out_out_out_out_3.handle_3 = dummy_handle_24;
  //             3 inline
  message.out_out_out_2.l3_inline.handle_3 = dummy_handle_25;
  //             handle
  message.out_out_out_2.handle_2 = dummy_handle_26;
  //         2 inline
  //             3 out of line
  message.out_out_in_out_3.handle_3 = dummy_handle_27;
  //             3 inline
  message.out_out_1.l2_inline.l3_inline.handle_3 = dummy_handle_28;
  //             handle
  message.out_out_1.l2_inline.handle_2 = dummy_handle_29;

  zx_handle_t handles[30] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&nested_struct_ptrs_message_type, &message, sizeof(message), handles,
                            ArrayCount(handles), &actual_handles, &error);

  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);

  EXPECT_EQ(handles[0], dummy_handle_0);
  EXPECT_EQ(handles[1], dummy_handle_1);
  EXPECT_EQ(handles[2], dummy_handle_2);
  EXPECT_EQ(handles[3], dummy_handle_3);
  EXPECT_EQ(handles[4], dummy_handle_4);
  EXPECT_EQ(handles[5], dummy_handle_5);
  EXPECT_EQ(handles[6], dummy_handle_6);
  EXPECT_EQ(handles[7], dummy_handle_7);
  EXPECT_EQ(handles[8], dummy_handle_8);
  EXPECT_EQ(handles[9], dummy_handle_9);
  EXPECT_EQ(handles[10], dummy_handle_10);
  EXPECT_EQ(handles[11], dummy_handle_11);
  EXPECT_EQ(handles[12], dummy_handle_12);
  EXPECT_EQ(handles[13], dummy_handle_13);
  EXPECT_EQ(handles[14], dummy_handle_14);
  EXPECT_EQ(handles[15], dummy_handle_15);
  EXPECT_EQ(handles[16], dummy_handle_16);
  EXPECT_EQ(handles[17], dummy_handle_17);
  EXPECT_EQ(handles[18], dummy_handle_18);
  EXPECT_EQ(handles[19], dummy_handle_19);
  EXPECT_EQ(handles[20], dummy_handle_20);
  EXPECT_EQ(handles[21], dummy_handle_21);
  EXPECT_EQ(handles[22], dummy_handle_22);
  EXPECT_EQ(handles[23], dummy_handle_23);
  EXPECT_EQ(handles[24], dummy_handle_24);
  EXPECT_EQ(handles[25], dummy_handle_25);
  EXPECT_EQ(handles[26], dummy_handle_26);
  EXPECT_EQ(handles[27], dummy_handle_27);
  EXPECT_EQ(handles[28], dummy_handle_28);
  EXPECT_EQ(handles[29], dummy_handle_29);

  // Finally, check that all absent members are FIDL_ALLOC_ABSENT.
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.inline_struct.l0_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.inline_struct.l0_inline.l1_absent),
            FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.inline_struct.l0_inline.l1_inline.l2_absent),
            FIDL_ALLOC_ABSENT);
  EXPECT_EQ(
      reinterpret_cast<uintptr_t>(message.inline_struct.l0_inline.l1_inline.l2_inline.l3_absent),
      FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.in_in_out_2.l3_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.in_out_1.l2_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.in_out_1.l2_inline.l3_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.in_out_out_2.l3_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.out_0.l1_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.out_0.l1_inline.l2_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.out_0.l1_inline.l2_inline.l3_absent),
            FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.out_in_out_2.l3_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.out_out_1.l2_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.out_out_1.l2_inline.l3_absent), FIDL_ALLOC_ABSENT);
  EXPECT_EQ(reinterpret_cast<uintptr_t>(message.out_out_out_2.l3_absent), FIDL_ALLOC_ABSENT);

  END_TEST;
}

void SetUpRecursionMessage(recursion_message_layout* message) {
  message->inline_struct.inline_union.tag = maybe_recurse_union_kMore;
  message->inline_struct.inline_union.more = &message->depth_0;
  message->depth_0.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_0.inline_union.more = &message->depth_1;
  message->depth_1.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_1.inline_union.more = &message->depth_2;
  message->depth_2.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_2.inline_union.more = &message->depth_3;
  message->depth_3.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_3.inline_union.more = &message->depth_4;
  message->depth_4.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_4.inline_union.more = &message->depth_5;
  message->depth_5.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_5.inline_union.more = &message->depth_6;
  message->depth_6.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_6.inline_union.more = &message->depth_7;
  message->depth_7.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_7.inline_union.more = &message->depth_8;
  message->depth_8.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_8.inline_union.more = &message->depth_9;
  message->depth_9.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_9.inline_union.more = &message->depth_10;
  message->depth_10.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_10.inline_union.more = &message->depth_11;
  message->depth_11.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_11.inline_union.more = &message->depth_12;
  message->depth_12.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_12.inline_union.more = &message->depth_13;
  message->depth_13.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_13.inline_union.more = &message->depth_14;
  message->depth_14.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_14.inline_union.more = &message->depth_15;
  message->depth_15.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_15.inline_union.more = &message->depth_16;
  message->depth_16.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_16.inline_union.more = &message->depth_17;
  message->depth_17.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_17.inline_union.more = &message->depth_18;
  message->depth_18.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_18.inline_union.more = &message->depth_19;
  message->depth_19.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_19.inline_union.more = &message->depth_20;
  message->depth_20.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_20.inline_union.more = &message->depth_21;
  message->depth_21.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_21.inline_union.more = &message->depth_22;
  message->depth_22.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_22.inline_union.more = &message->depth_23;
  message->depth_23.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_23.inline_union.more = &message->depth_24;
  message->depth_24.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_24.inline_union.more = &message->depth_25;
  message->depth_25.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_25.inline_union.more = &message->depth_26;
  message->depth_26.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_26.inline_union.more = &message->depth_27;
  message->depth_27.inline_union.tag = maybe_recurse_union_kMore;
  message->depth_27.inline_union.more = &message->depth_28;
}

bool encode_nested_struct_recursion_too_deep_error() {
  BEGIN_TEST;

  recursion_message_layout message = {};
  // First we check that FIDL_RECURSION_DEPTH - 1 levels of recursion is OK.
  SetUpRecursionMessage(&message);
  message.depth_28.inline_union.tag = maybe_recurse_union_kDone;
  message.depth_28.inline_union.handle = dummy_handle_0;

  zx_handle_t handles[1] = {};

  const char* error = nullptr;
  uint32_t actual_handles = 0u;
  auto status = fidl_encode(&recursion_message_type, &message,
                            // Tell it to ignore everything after we stop recursion.
                            offsetof(recursion_message_layout, depth_29), handles,
                            ArrayCount(handles), &actual_handles, &error);
  EXPECT_EQ(status, ZX_OK);
  EXPECT_NULL(error, error);

  // Now add another level of recursion.
  SetUpRecursionMessage(&message);
  message.depth_28.inline_union.tag = maybe_recurse_union_kMore;
  message.depth_28.inline_union.more = &message.depth_29;
  message.depth_29.inline_union.tag = maybe_recurse_union_kDone;
  message.depth_29.inline_union.handle = dummy_handle_0;

  error = nullptr;
  actual_handles = 0u;
  status = fidl_encode(&recursion_message_type, &message, sizeof(message), handles,
                       ArrayCount(handles), &actual_handles, &error);
  EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
  EXPECT_NONNULL(error);
  const char expected_error_msg[] = "recursion depth exceeded processing struct";
  EXPECT_STR_EQ(expected_error_msg, error, "wrong error msg");

  END_TEST;
}

BEGIN_TEST_CASE(null_parameters)
RUN_TEST(encode_null_encode_parameters)
END_TEST_CASE(null_parameters)

BEGIN_TEST_CASE(unaligned)
RUN_TEST(encode_single_present_handle_unaligned_error)
RUN_TEST(encode_present_nonnullable_string_unaligned_error)
END_TEST_CASE(unaligned)

BEGIN_TEST_CASE(handles)
RUN_TEST(encode_single_present_handle)
RUN_TEST(encode_single_present_handle_zero_trailing_padding)
RUN_TEST(encode_too_many_bytes_specified_should_close_handles)
RUN_TEST(encode_multiple_present_handles)
RUN_TEST(encode_single_absent_handle)
RUN_TEST(encode_multiple_absent_handles)
END_TEST_CASE(handles)

BEGIN_TEST_CASE(arrays)
RUN_TEST(encode_array_of_present_handles)
RUN_TEST(encode_array_of_nullable_handles)
RUN_TEST(encode_array_of_nullable_handles_with_insufficient_handles_error)
RUN_TEST(encode_array_of_array_of_present_handles)
RUN_TEST(encode_out_of_line_array_of_nonnullable_handles)
RUN_TEST(encode_array_of_present_handles_error_closes_handles)
END_TEST_CASE(arrays)

BEGIN_TEST_CASE(strings)
RUN_TEST(encode_present_nonnullable_string)
RUN_TEST(encode_multiple_present_nullable_string)
RUN_TEST(encode_present_nullable_string)
RUN_TEST(encode_absent_nonnullable_string_error)
RUN_TEST(encode_absent_nullable_string)
RUN_TEST(encode_present_nonnullable_bounded_string)
RUN_TEST(encode_present_nullable_bounded_string)
RUN_TEST(encode_absent_nonnullable_bounded_string_error)
RUN_TEST(encode_absent_nullable_bounded_string)
RUN_TEST(encode_present_nonnullable_bounded_string_short_error)
RUN_TEST(encode_present_nullable_bounded_string_short_error)
END_TEST_CASE(strings)

BEGIN_TEST_CASE(vectors)
RUN_TEST(encode_vector_with_huge_count)
RUN_TEST(encode_present_nonnullable_vector_of_handles)
RUN_TEST(encode_present_nullable_vector_of_handles)
RUN_TEST(encode_absent_nonnullable_vector_of_handles_error)
RUN_TEST(encode_absent_nullable_vector_of_handles)
RUN_TEST(encode_present_nonnullable_bounded_vector_of_handles)
RUN_TEST(encode_present_nullable_bounded_vector_of_handles)
RUN_TEST(encode_absent_nonnullable_bounded_vector_of_handles)
RUN_TEST(encode_absent_nullable_bounded_vector_of_handles)
RUN_TEST(encode_present_nonnullable_bounded_vector_of_handles_short_error)
RUN_TEST(encode_present_nullable_bounded_vector_of_handles_short_error)
RUN_TEST(encode_present_nonnullable_vector_of_uint32)
RUN_TEST(encode_present_nullable_vector_of_uint32)
RUN_TEST(encode_absent_nonnullable_vector_of_uint32_error)
RUN_TEST(encode_absent_and_empty_nonnullable_vector_of_uint32_error)
RUN_TEST(encode_absent_nullable_vector_of_uint32)
RUN_TEST(encode_absent_nullable_vector_of_uint32_non_zero_length_error)
RUN_TEST(encode_present_nonnullable_bounded_vector_of_uint32)
RUN_TEST(encode_present_nullable_bounded_vector_of_uint32)
RUN_TEST(encode_absent_nonnullable_bounded_vector_of_uint32)
RUN_TEST(encode_absent_nullable_bounded_vector_of_uint32)
RUN_TEST(encode_present_nonnullable_bounded_vector_of_uint32_short_error)
RUN_TEST(encode_present_nullable_bounded_vector_of_uint32_short_error)
END_TEST_CASE(vectors)

BEGIN_TEST_CASE(unions)
RUN_TEST(encode_bad_tagged_union_error)
RUN_TEST(encode_single_armed_present_nonnullable_union)
RUN_TEST(encode_many_armed_present_nonnullable_union)
RUN_TEST(encode_many_armed_present_nonnullable_union_zero_trailing_padding)
RUN_TEST(encode_single_armed_present_nullable_union)
RUN_TEST(encode_many_armed_present_nullable_union)
RUN_TEST(encode_single_armed_absent_nullable_union)
RUN_TEST(encode_many_armed_absent_nullable_union)
END_TEST_CASE(unions)

BEGIN_TEST_CASE(structs)
RUN_TEST(encode_nested_nonnullable_structs)
RUN_TEST(encode_nested_nonnullable_structs_zero_padding)
RUN_TEST(encode_nested_nullable_structs)
RUN_TEST(encode_nested_struct_recursion_too_deep_error)
END_TEST_CASE(structs)

}  // namespace
}  // namespace fidl