// Copyright 2018 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 <cstddef>
#include <limits.h>
#include <memory>

#include <lib/fidl/coding.h>
#include <lib/fidl/cpp/string_view.h>
#include <lib/fidl/cpp/vector_view.h>
#include <unittest/unittest.h>
#include <zircon/syscalls.h>

#include "fidl_coded_types.h"
#include "fidl_structs.h"
#include "fidl/extra_messages.h"

namespace fidl {
namespace {

bool linearize_present_nonnullable_string() {
    BEGIN_TEST;

    unbounded_nonnullable_string_inline_data message = {};
    constexpr const char* kStr = "hello!";
    constexpr size_t kLength = 6;

    char some_other_string[kLength] = {0};
    message.string = fidl_string_t{kLength, some_other_string};
    memcpy(some_other_string, kStr, kLength);

    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;

    // Manually compute linearized size
    constexpr uint32_t buf_size = 32u + FIDL_ALIGN(kLength);
    // Allocate a buffer of the specified size
    std::unique_ptr<uint8_t[]> buf(new uint8_t[buf_size]);
    status = fidl_linearize(&unbounded_nonnullable_string_message_type,
                            &message, buf.get(), buf_size, &actual_num_bytes, &error);
    EXPECT_EQ(status, ZX_OK);
    EXPECT_NULL(error, error);
    EXPECT_EQ(actual_num_bytes, buf_size);
    // Verify pointers and object packing
    auto inline_data = reinterpret_cast<unbounded_nonnullable_string_inline_data*>(buf.get());
    EXPECT_EQ(static_cast<void*>(inline_data->string.data),
              static_cast<void*>(&buf[FIDL_ALIGN(sizeof(message))]));
    EXPECT_BYTES_EQ(reinterpret_cast<const uint8_t*>("hello!"),
                    reinterpret_cast<const uint8_t*>(inline_data->string.data),
                    kLength,
                    "Secondary object string must be hello!");

    END_TEST;
}

bool linearize_present_nonnullable_string_unaligned_error() {
    BEGIN_TEST;

    unbounded_nonnullable_string_inline_data message = {};
    constexpr const char* kStr = "hello!";
    constexpr size_t kLength = 6;

    char some_other_string[kLength] = {0};
    message.string = fidl_string_t{kLength, some_other_string};
    memcpy(some_other_string, kStr, kLength);

    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;

    // Pass in an unaligned storage
    constexpr uint32_t buf_size = 32u + FIDL_ALIGN(kLength);
    std::unique_ptr<uint8_t[]> buf(new uint8_t[buf_size * 2]);
    uint8_t* unaligned_ptr = buf.get() + 1;
    status = fidl_linearize(&unbounded_nonnullable_string_message_type,
                            &message, unaligned_ptr, buf_size, &actual_num_bytes, &error);
    EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
    EXPECT_NONNULL(error);
    ASSERT_STR_STR(error, "must be aligned to FIDL_ALIGNMENT");

    END_TEST;
}

bool linearize_present_nonnullable_longer_string() {
    BEGIN_TEST;

    unbounded_nonnullable_string_inline_data message = {};
    constexpr const char* kStr = "hello world!";
    constexpr size_t kLength = 12;

    char some_other_string[kLength] = {0};
    message.string = fidl_string_t{kLength, some_other_string};
    memcpy(some_other_string, kStr, kLength);

    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;

    // Manually compute linearized size
    constexpr uint32_t buf_size = 32u + FIDL_ALIGN(kLength);

    // For non-handle-containing structures, linearizing should not change anything
    const unbounded_nonnullable_string_inline_data message_shallow_copy = message;

    // Allocate a buffer of the specified size
    std::unique_ptr<uint8_t[]> buf(new uint8_t[buf_size]);
    status = fidl_linearize(&unbounded_nonnullable_string_message_type,
                            &message, buf.get(), buf_size, &actual_num_bytes, &error);
    EXPECT_EQ(status, ZX_OK);
    EXPECT_NULL(error, error);
    EXPECT_EQ(actual_num_bytes, buf_size);
    // Verify pointers and object packing
    auto inline_data = reinterpret_cast<unbounded_nonnullable_string_inline_data*>(buf.get());
    EXPECT_EQ(static_cast<void*>(inline_data->string.data),
            static_cast<void*>(&buf[FIDL_ALIGN(sizeof(message))]));
    EXPECT_BYTES_EQ(reinterpret_cast<const uint8_t*>("hello world!"),
                    reinterpret_cast<const uint8_t*>(inline_data->string.data),
                    kLength,
                    "Secondary object string must be hello world!");
    // Verify that message is not destroyed
    EXPECT_BYTES_EQ(reinterpret_cast<const uint8_t*>(&message_shallow_copy),
                    reinterpret_cast<uint8_t*>(&message),
                    sizeof(message),
                    "Input object should not change");

    // Linearizing with a buffer size smaller than allowed should error out
    status = fidl_linearize(&unbounded_nonnullable_string_message_type,
                            &message, buf.get(), buf_size - 1, nullptr, &error);
    EXPECT_EQ(status, ZX_ERR_BUFFER_TOO_SMALL);
    EXPECT_NONNULL(error, "Should report error when buffer too small");

    END_TEST;
}

bool linearize_vector_of_uint32() {
    BEGIN_TEST;

    // Linearizing this array...
    constexpr uint32_t array_len = 40;
    std::unique_ptr<uint32_t[]> numbers(new uint32_t[array_len]);
    for (uint32_t i = 0; i < array_len; i++) {
        numbers[i] = i;
    }
    // into this buffer, which is big enough for the entire message
    constexpr uint32_t buf_size = 512;
    std::unique_ptr<uint8_t[]> buffer(new uint8_t[buf_size]);

    unbounded_nonnullable_vector_of_uint32_inline_data message = {};
    message.header.flags = 123;
    message.header.ordinal = 456;
    message.header.txid = 789;
    message.vector = (fidl_vector_t) {
        .count = array_len,
        .data = numbers.get(),
    };

    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;
    status = fidl_linearize(&unbounded_nonnullable_vector_of_uint32_message_type,
                            &message,
                            buffer.get(),
                            buf_size,
                            &actual_num_bytes,
                            &error);
    ASSERT_EQ(status, ZX_OK);
    ASSERT_NULL(error, error);
    ASSERT_GT(actual_num_bytes, sizeof(message));

    // Verify that vector contents have been copied copied correctly
    auto linearized_message =
        reinterpret_cast<unbounded_nonnullable_vector_of_uint32_inline_data*>(buffer.get());
    EXPECT_NONNULL(linearized_message->vector.data);
    EXPECT_NE(linearized_message->vector.data, message.vector.data);
    auto copied_numbers = reinterpret_cast<uint32_t*>(linearized_message->vector.data);
    for (uint32_t i = 0; i < array_len; i++) {
        EXPECT_EQ(copied_numbers[i], i);
    }
    EXPECT_EQ(memcmp(&message.header,
                     &linearized_message->header,
                     sizeof(message.header)), 0);

    // Verify that linearizing with less number of bytes does fail
    status = fidl_linearize(&unbounded_nonnullable_vector_of_uint32_message_type,
                            &message,
                            buffer.get(),
                            actual_num_bytes - 1,
                            nullptr,
                            &error);
    EXPECT_EQ(status, ZX_ERR_BUFFER_TOO_SMALL);
    EXPECT_NONNULL(error);

    END_TEST;
}

bool linearize_vector_of_string() {
    BEGIN_TEST;

    // Define the memory-layout of the inline object
    struct VectorOfStringRequest {
        alignas(FIDL_ALIGNMENT)
        fidl_message_header_t header;
        fidl::VectorView<fidl::StringView> vector;
    };

    // Serialize these strings...
    const char str1[] = "Open connection,";
    const char str2[] = "Send the wrong FIDL message,";
    const char str3[] = "Get an epitaph.";
    // into this buffer, which is big enough for the entire message
    constexpr uint32_t buf_size = 512;
    std::unique_ptr<uint8_t[]> buffer(new uint8_t[buf_size]);

    fidl::StringView strings[3] = {};
    strings[0].set_data(str1);
    strings[0].set_size(sizeof(str1));
    strings[1].set_data(str2);
    strings[1].set_size(sizeof(str2));
    strings[2].set_data(str3);
    strings[2].set_size(sizeof(str3));

    VectorOfStringRequest message;
    message.vector.set_data(strings);
    message.vector.set_count(3);

    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;
    status = fidl_linearize(&fidl_test_coding_LinearizerTestVectorOfStringRequestTable,
                            &message,
                            buffer.get(),
                            buf_size,
                            &actual_num_bytes,
                            &error);
    ASSERT_EQ(status, ZX_OK);
    ASSERT_NULL(error, error);
    ASSERT_GT(actual_num_bytes, sizeof(message));

    // Verify that vector contents have been copied copied correctly
    auto linearized_message =
        reinterpret_cast<VectorOfStringRequest*>(buffer.get());
    EXPECT_NONNULL(linearized_message->vector.data());
    EXPECT_EQ(linearized_message->vector.count(), 3);

    EXPECT_NE(linearized_message->vector[0].data(), str1);
    EXPECT_BYTES_EQ(
        reinterpret_cast<const uint8_t*>(linearized_message->vector[0].data()),
        reinterpret_cast<const uint8_t*>(str1),
        sizeof(str1),
        str1);
    EXPECT_NE(linearized_message->vector[1].data(), str2);
    EXPECT_BYTES_EQ(
        reinterpret_cast<const uint8_t*>(linearized_message->vector[1].data()),
        reinterpret_cast<const uint8_t*>(str2),
        sizeof(str2),
        str2);
    EXPECT_NE(linearized_message->vector[2].data(), str3);
    EXPECT_BYTES_EQ(
        reinterpret_cast<const uint8_t*>(linearized_message->vector[2].data()),
        reinterpret_cast<const uint8_t*>(str3),
        sizeof(str3),
        str3);

    END_TEST;
}

bool linearize_struct_with_handle() {
    BEGIN_TEST;

    constexpr zx_handle_t dummy_handle = static_cast<zx_handle_t>(42);

    // Define the memory-layout of the inline object
    struct StructWithHandle {
        alignas(FIDL_ALIGNMENT)
        zx_handle_t h;
        int32_t foo;
    };

    // Since there are no out-of-line objects, the size is known
    constexpr uint32_t buf_size = sizeof(StructWithHandle);
    StructWithHandle message = {
        .h = dummy_handle,
        .foo = 0,
    };
    uint8_t buffer[buf_size];

    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;
    status = fidl_linearize(&fidl_test_coding_StructWithHandleTable,
                            &message,
                            buffer,
                            buf_size,
                            &actual_num_bytes,
                            &error);
    ASSERT_EQ(status, ZX_OK);
    ASSERT_EQ(actual_num_bytes, sizeof(StructWithHandle));
    ASSERT_NULL(error, error);

    // Handles in the original object are moved
    auto linearized_message = reinterpret_cast<StructWithHandle*>(buffer);
    EXPECT_EQ(message.h, ZX_HANDLE_INVALID);
    EXPECT_EQ(linearized_message->h, dummy_handle);

    END_TEST;
}

bool linearize_struct_with_many_handles() {
    BEGIN_TEST;

    zx_handle_t dummy_handles[4] = {};
    auto handle_value_at = [] (int i) ->zx_handle_t { return static_cast<zx_handle_t>(100 + i); };
    for (int i = 0; i < 4; i++) {
        dummy_handles[i] = handle_value_at(i);
    }

    // Define the memory-layout of the inline object
    struct StructWithManyHandles {
        alignas(FIDL_ALIGNMENT)
        zx_handle_t h1;
        zx_handle_t h2;
        fidl::VectorView<zx_handle_t> hs;
    };

    fidl::VectorView<zx_handle_t> hs;
    hs.set_count(2);
    hs.set_data(&dummy_handles[2]);

    constexpr uint32_t buf_size = 512;
    StructWithManyHandles message = {
        .h1 = dummy_handles[0],
        .h2 = dummy_handles[1],
        .hs = hs,
    };
    uint8_t buffer[buf_size];

    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;
    status = fidl_linearize(&fidl_test_coding_StructWithManyHandlesTable,
                            &message,
                            buffer,
                            buf_size,
                            &actual_num_bytes,
                            &error);
    ASSERT_EQ(status, ZX_OK);
    ASSERT_GT(actual_num_bytes, sizeof(StructWithManyHandles));
    ASSERT_NULL(error, error);

    // Handles in the original object are moved
    auto linearized_message = reinterpret_cast<StructWithManyHandles*>(buffer);
    EXPECT_EQ(message.h1, ZX_HANDLE_INVALID);
    EXPECT_EQ(message.h2, ZX_HANDLE_INVALID);
    EXPECT_EQ(message.hs[0], ZX_HANDLE_INVALID);
    EXPECT_EQ(message.hs[1], ZX_HANDLE_INVALID);
    EXPECT_EQ(linearized_message->h1, handle_value_at(0));
    EXPECT_EQ(linearized_message->h2, handle_value_at(1));
    EXPECT_EQ(linearized_message->hs[0], handle_value_at(2));
    EXPECT_EQ(linearized_message->hs[1], handle_value_at(3));

    END_TEST;
}

bool linearize_simple_table() {
    BEGIN_TEST;

    SimpleTableEnvelopes envelopes = {};
    SimpleTable simple_table;
    simple_table.set_count(5);
    simple_table.set_data(&envelopes.x);

    IntStruct x = {10};
    IntStruct y = {20};
    envelopes.x.data = &x;
    envelopes.y.data = &y;

    // Attempt to linearize with different table schemas to verify evolution-compatibility
    for (auto coding_table : {
        &fidl_test_coding_SimpleTableTable,
        &fidl_test_coding_NewerSimpleTableTable
    }) {
        constexpr uint32_t buf_size = 512;
        uint8_t buffer[buf_size];
        const char* error = nullptr;
        zx_status_t status;
        uint32_t actual_num_bytes = 0;
        status = fidl_linearize(coding_table,
                                &simple_table,
                                buffer,
                                buf_size,
                                &actual_num_bytes,
                                &error);
        EXPECT_EQ(status, ZX_OK);
        EXPECT_GT(actual_num_bytes, sizeof(SimpleTable));
        EXPECT_NULL(error, error);

        // Verify object placement
        const auto& linearized = *reinterpret_cast<SimpleTable*>(buffer);
        EXPECT_EQ(reinterpret_cast<IntStruct*>(linearized[0].data)->v, 10);
        EXPECT_EQ(reinterpret_cast<IntStruct*>(linearized[4].data)->v, 20);

        // Verify auto-filling envelope header
        for (int i = 0; i < 5; i++) {
            if (i == 0 || i == 4) {
                EXPECT_EQ(linearized[i].num_bytes, 8);
                EXPECT_EQ(linearized[i].num_handles, 0);
            } else {
                EXPECT_EQ(linearized[i].num_bytes, 0);
                EXPECT_EQ(linearized[i].num_handles, 0);
            }
        }
    }

    // Alternative version with only x set, such that we can use OlderSimpleTable
    envelopes.y.data = nullptr;
    // Attempt to linearize with different table schemas to verify evolution-compatibility
    for (auto coding_table : {
        &fidl_test_coding_OlderSimpleTableTable,
        &fidl_test_coding_SimpleTableTable,
        &fidl_test_coding_NewerSimpleTableTable
    }) {
        constexpr uint32_t buf_size = 512;
        uint8_t buffer[buf_size];
        const char* error = nullptr;
        zx_status_t status;
        uint32_t actual_num_bytes = 0;
        status = fidl_linearize(coding_table,
                                &simple_table,
                                buffer,
                                buf_size,
                                &actual_num_bytes,
                                &error);
        EXPECT_EQ(status, ZX_OK);
        EXPECT_GT(actual_num_bytes, sizeof(SimpleTable));
        EXPECT_NULL(error, error);

        // Verify object placement
        const auto& linearized = *reinterpret_cast<SimpleTable*>(buffer);
        EXPECT_EQ(reinterpret_cast<IntStruct*>(linearized[0].data)->v, 10);

        // Verify auto-filling envelope header
        EXPECT_EQ(linearized[0].num_bytes, 8);
        EXPECT_EQ(linearized[0].num_handles, 0);
        for (int i = 1; i < 5; i++) {
            EXPECT_EQ(linearized[i].num_bytes, 0);
            EXPECT_EQ(linearized[i].num_handles, 0);
        }
    }

    // If y is set,
    envelopes.y.data = &y;
    // but OlderSimpleTable is used, it should error as the walker does not know how to process y.
    {
        constexpr uint32_t buf_size = 512;
        uint8_t buffer[buf_size];
        const char* error = nullptr;
        zx_status_t status;
        uint32_t actual_num_bytes = 0;
        status = fidl_linearize(&fidl_test_coding_OlderSimpleTableTable,
                                &simple_table,
                                buffer,
                                buf_size,
                                &actual_num_bytes,
                                &error);
        EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
        EXPECT_EQ(actual_num_bytes, 0);
        EXPECT_NONNULL(error);
    }

    END_TEST;
}

namespace {

bool linearize_table_field_1() {
    BEGIN_TEST;

    TableOfStructEnvelopes envelopes = {};
    TableOfStruct table;
    table.set_count(1);
    table.set_data(&envelopes.a);

    constexpr zx_handle_t dummy_handle = static_cast<zx_handle_t>(42);
    OrdinalOneStructWithHandle ordinal1 = {
        .h = dummy_handle,
        .foo = 0
    };
    envelopes.a.data = &ordinal1;

    constexpr uint32_t buf_size = 512;
    uint8_t buffer[buf_size];
    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;
    status = fidl_linearize(&fidl_test_coding_TableOfStructWithHandleTable,
                            &table,
                            buffer,
                            buf_size,
                            &actual_num_bytes,
                            &error);
    EXPECT_EQ(status, ZX_OK);
    EXPECT_GT(actual_num_bytes, sizeof(TableOfStruct));
    EXPECT_NULL(error, error);

    // Verify that handles have been moved
    const auto& linearized = *reinterpret_cast<TableOfStruct*>(buffer);
    EXPECT_EQ(reinterpret_cast<OrdinalOneStructWithHandle*>(linearized[0].data)->h, dummy_handle);
    EXPECT_EQ(ordinal1.h, ZX_HANDLE_INVALID);

    // Verify auto-filling envelope header
    EXPECT_EQ(linearized[0].num_bytes, sizeof(ordinal1));
    EXPECT_EQ(linearized[0].num_handles, 1);

    END_TEST;
}

bool linearize_table_field_2() {
    BEGIN_TEST;

    TableOfStructEnvelopes envelopes = {};
    TableOfStruct table;
    table.set_count(2);
    table.set_data(&envelopes.a);

    zx_handle_t dummy_handles[4] = {};
    auto handle_value_at = [] (int i) -> zx_handle_t { return static_cast<zx_handle_t>(100 + i); };
    for (int i = 0; i < 4; i++) {
        dummy_handles[i] = handle_value_at(i);
    }
    fidl::VectorView<zx_handle_t> hs;
    hs.set_count(2);
    hs.set_data(&dummy_handles[2]);

    OrdinalTwoStructWithManyHandles ordinal2 = {
        .h1 = dummy_handles[0],
        .h2 = dummy_handles[1],
        .hs = hs,
    };
    envelopes.b.data = &ordinal2;

    constexpr uint32_t buf_size = 512;
    uint8_t buffer[buf_size];
    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;
    status = fidl_linearize(&fidl_test_coding_TableOfStructWithHandleTable,
                            &table,
                            buffer,
                            buf_size,
                            &actual_num_bytes,
                            &error);
    EXPECT_EQ(status, ZX_OK);
    EXPECT_GT(actual_num_bytes, sizeof(TableOfStruct));
    EXPECT_NULL(error, error);

    // Verify that handles have been moved
    const auto& linearized = *reinterpret_cast<TableOfStruct*>(buffer);
    auto linearized_field = reinterpret_cast<OrdinalTwoStructWithManyHandles*>(linearized[1].data);
    ASSERT_NONNULL(linearized_field);
    EXPECT_EQ(linearized_field->h1, handle_value_at(0));
    EXPECT_EQ(ordinal2.h1, ZX_HANDLE_INVALID);
    EXPECT_EQ(linearized_field->h2, handle_value_at(1));
    EXPECT_EQ(ordinal2.h2, ZX_HANDLE_INVALID);
    EXPECT_EQ(linearized_field->hs[0], handle_value_at(2));
    EXPECT_EQ(ordinal2.hs[0], ZX_HANDLE_INVALID);
    EXPECT_EQ(linearized_field->hs[1], handle_value_at(3));
    EXPECT_EQ(ordinal2.hs[1], ZX_HANDLE_INVALID);


    // Verify auto-filling envelope header
    EXPECT_EQ(linearized[0].num_bytes, 0);
    EXPECT_EQ(linearized[0].num_handles, 0);
    EXPECT_EQ(linearized[1].num_bytes,
              FIDL_ALIGN(sizeof(ordinal2)) + sizeof(zx_handle_t) * hs.count());
    EXPECT_EQ(linearized[1].num_handles, 4);

    END_TEST;
}

} // namespace

bool linearize_xunion_empty_invariant_empty() {
    BEGIN_TEST;

    // Non-zero ordinal with empty envelope is an error
    SampleNullableXUnionStruct xunion = {};
    xunion.opt_xu.header = (fidl_xunion_t) {
        .tag = kSampleXUnionIntStructOrdinal,
        .padding = 0,
        .envelope = {}
    };
    constexpr uint32_t buf_size = 512;
    uint8_t buffer[buf_size];
    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;
    status = fidl_linearize(&fidl_test_coding_SampleNullableXUnionStructTable,
                            &xunion,
                            buffer,
                            buf_size,
                            &actual_num_bytes,
                            &error);
    EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
    EXPECT_NONNULL(error);
    EXPECT_STR_EQ(error, "empty xunion must have zero as ordinal");

    END_TEST;
}

bool linearize_xunion_empty_invariant_zero_ordinal() {
    BEGIN_TEST;

    // Zero ordinal with non-empty envelope is an error
    IntStruct int_struct = {
        .v = 100
    };
    SampleNullableXUnionStruct xunion = {};
    xunion.opt_xu.header = (fidl_xunion_t) {
        .tag = 0,
        .padding = 0,
        .envelope = (fidl_envelope_t) {
            .num_bytes = 8,
            .num_handles = 0,
            .data = &int_struct
        }
    };
    constexpr uint32_t buf_size = 512;
    uint8_t buffer[buf_size];
    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;
    status = fidl_linearize(&fidl_test_coding_SampleNullableXUnionStructTable,
                            &xunion,
                            buffer,
                            buf_size,
                            &actual_num_bytes,
                            &error);
    EXPECT_EQ(status, ZX_ERR_INVALID_ARGS);
    EXPECT_NONNULL(error);
    EXPECT_STR_EQ(error, "xunion with zero as ordinal must be empty");

    END_TEST;
}

bool linearize_xunion_primitive_field() {
    BEGIN_TEST;

    int32_t raw_int = 42;
    SampleXUnionStruct xunion = {};
    xunion.xu.header = (fidl_xunion_t) {
        .tag = kSampleXUnionRawIntOrdinal,
        .padding = 0,
        .envelope = (fidl_envelope_t) {
            .num_bytes = 0,
            .num_handles = 0,
            .data = &raw_int
        }
    };
    constexpr uint32_t buf_size = 512;
    uint8_t buffer[buf_size];
    const char* error = nullptr;
    zx_status_t status;
    uint32_t actual_num_bytes = 0;
    status = fidl_linearize(&fidl_test_coding_SampleXUnionStructTable,
                            &xunion,
                            buffer,
                            buf_size,
                            &actual_num_bytes,
                            &error);
    EXPECT_EQ(status, ZX_OK);
    EXPECT_NULL(error, error);

    uint8_t golden_linearized_prefix[] = {
        0xe3, 0x60, 0x0e, 0x13, // The ordinal value is 0x130e60e3
        0x00, 0x00, 0x00, 0x00, // xunion padding
        0x08, 0x00, 0x00, 0x00, // num_bytes of envelope
        0x00, 0x00, 0x00, 0x00, // num_handles of envelope
        // The out-of-line address of the payload would follow.
    };
    constexpr uint32_t kEnvelopeDataPointerSize = sizeof(uintptr_t);
    constexpr uint32_t kEnvelopePayloadSize = fidl::FidlAlign(sizeof(int32_t));
    ASSERT_EQ(actual_num_bytes,
              sizeof(golden_linearized_prefix) + kEnvelopeDataPointerSize + kEnvelopePayloadSize);
    ASSERT_BYTES_EQ(buffer, golden_linearized_prefix, sizeof(golden_linearized_prefix),
                    "linearized result is different from goldens");
    SampleXUnionStruct* linearized = reinterpret_cast<SampleXUnionStruct*>(&buffer[0]);
    int32_t* payload_addr = reinterpret_cast<int32_t*>(linearized->xu.header.envelope.data);
    std::ptrdiff_t distance = reinterpret_cast<uint8_t*>(payload_addr) - &buffer[0];
    ASSERT_EQ(distance,
              sizeof(golden_linearized_prefix) + kEnvelopeDataPointerSize);
    ASSERT_EQ(*payload_addr, raw_int);

    END_TEST;
}

BEGIN_TEST_CASE(strings)
RUN_TEST(linearize_present_nonnullable_string)
RUN_TEST(linearize_present_nonnullable_longer_string)
END_TEST_CASE(strings)

BEGIN_TEST_CASE(unaligned)
RUN_TEST(linearize_present_nonnullable_string_unaligned_error)
END_TEST_CASE(unaligned)

BEGIN_TEST_CASE(vectors)
RUN_TEST(linearize_vector_of_uint32)
RUN_TEST(linearize_vector_of_string)
END_TEST_CASE(vectors)

BEGIN_TEST_CASE(handles)
RUN_TEST(linearize_struct_with_handle)
RUN_TEST(linearize_struct_with_many_handles)
END_TEST_CASE(handles)

BEGIN_TEST_CASE(tables)
RUN_TEST(linearize_simple_table)
RUN_TEST(linearize_table_field_1)
RUN_TEST(linearize_table_field_2)
END_TEST_CASE(tables)

BEGIN_TEST_CASE(xunions)
RUN_TEST(linearize_xunion_empty_invariant_empty)
RUN_TEST(linearize_xunion_empty_invariant_zero_ordinal)
RUN_TEST(linearize_xunion_primitive_field)
END_TEST_CASE(xunions)


} // namespace
} // namespace fidl