/*
 * Copyright 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// The API layer of the loader defines Vulkan API and manages layers.  The
// entrypoints are generated and defined in api_dispatch.cpp.  Most of them
// simply find the dispatch table and jump.
//
// There are a few of them requiring manual code for things such as layer
// discovery or chaining.  They call into functions defined in this file.

#define ATRACE_TAG ATRACE_TAG_GRAPHICS

#include <stdlib.h>
#include <string.h>

#include <algorithm>
#include <mutex>
#include <new>
#include <string>
#include <unordered_set>
#include <utility>

#include <android-base/properties.h>
#include <android-base/strings.h>
#include <cutils/properties.h>
#include <log/log.h>
#include <utils/Trace.h>

#include <vulkan/vk_layer_interface.h>
#include <graphicsenv/GraphicsEnv.h>
#include "api.h"
#include "driver.h"
#include "layers_extensions.h"

#include <com_android_graphics_libvulkan_flags.h>

using namespace com::android::graphics::libvulkan;

namespace vulkan {
namespace api {

namespace {

// Provide overridden layer names when there are implicit layers.  No effect
// otherwise.
class OverrideLayerNames {
   public:
    OverrideLayerNames(bool is_instance, const VkAllocationCallbacks& allocator)
        : is_instance_(is_instance),
          allocator_(allocator),
          scope_(VK_SYSTEM_ALLOCATION_SCOPE_COMMAND),
          names_(nullptr),
          name_count_(0),
          implicit_layers_() {
        implicit_layers_.result = VK_SUCCESS;
    }

    ~OverrideLayerNames() {
        allocator_.pfnFree(allocator_.pUserData, names_);
        allocator_.pfnFree(allocator_.pUserData, implicit_layers_.elements);
        allocator_.pfnFree(allocator_.pUserData, implicit_layers_.name_pool);
    }

    /* Build an array of layer names that should be enabled, compiled from:
     *
     * - Settings-enabled implicit layers
     * - Appplication-requested explicit layers
     * - Platform layers
     * - OEM layers
     *
     * TODO (b/455899446): Potentially restrict AddImplicitLayers() from
     * including EXPLICIT layers (i.e. disallow layers from the application's
     * own APK from being enabled via the IMPLICIT layer mechanism, via debug
     * settings).
     */
    VkResult Parse(const char* const* names, uint32_t count) {
        // Determine which implicit layers are enabled by settings
        AddImplicitLayers();

        const auto& arr = implicit_layers_;
        if (arr.result != VK_SUCCESS)
            return arr.result;

        // No need to override when there are no implicit layers nor OPLs
        uint32_t oemAndPlatformLayerCount = GetOemAndPlatformLayerCount();
        uint32_t layersToAdd = arr.count + oemAndPlatformLayerCount;
        if (!layersToAdd)
            return VK_SUCCESS;

        // Allocate memory for implicit layer names
        names_ = AllocateNameArray(layersToAdd + count);
        if (!names_)
            return VK_ERROR_OUT_OF_HOST_MEMORY;

        // Add implicit layer names
        for (uint32_t i = 0; i < arr.count; i++)
            names_[i] = GetImplicitLayerName(i);

        // Update name_count_
        name_count_ = arr.count;

        // Add explicit layer names
        for (uint32_t i = 0; i < count; i++) {
            // ignore explicit layers that are also implicit
            if (IsImplicitLayer(names[i]))
                continue;

            names_[name_count_++] = names[i];
        }

        // Add platform and OEM layer names
        uint32_t oplStartIdx = GetEnumeratedLayerCount();
        for (uint32_t i = oplStartIdx; i < oemAndPlatformLayerCount; i++) {
            names_[name_count_++] = GetLayerProperties(GetLayer(i)).layerName;
        }

        return VK_SUCCESS;
    }

    const char* const* Names() const { return names_; }

    uint32_t Count() const { return name_count_; }

   private:
    struct ImplicitLayer {
        int priority;
        size_t name_offset;
    };

    struct ImplicitLayerArray {
        ImplicitLayer* elements;
        uint32_t max_count;
        uint32_t count;

        char* name_pool;
        size_t max_pool_size;
        size_t pool_size;

        VkResult result;
    };

    void AddImplicitLayers() {
        if (!is_instance_)
            return;

        GetLayersFromSettings();

        // If no layers specified via Settings, check legacy properties
        if (implicit_layers_.count <= 0) {
            ParseDebugVulkanLayers();
            ParseDebugVulkanLayer();

            // sort by priorities
            auto& arr = implicit_layers_;
            std::sort(arr.elements, arr.elements + arr.count,
                      [](const ImplicitLayer& a, const ImplicitLayer& b) {
                          return (a.priority < b.priority);
                      });
        }
    }

    void GetLayersFromSettings() {
        // These will only be available if conditions are met in GraphicsEnvironment
        // gpu_debug_layers = layer1:layer2:layerN
        const std::string layers = android::GraphicsEnv::getInstance().getDebugLayers();
        if (!layers.empty()) {
            ALOGV("Debug layer list: %s", layers.c_str());
            std::vector<std::string> paths = android::base::Split(layers, ":");
            for (uint32_t i = 0; i < paths.size(); i++) {
                AddImplicitLayer(int(i), paths[i].c_str(), paths[i].length());
            }
        }
    }

    void ParseDebugVulkanLayers() {
        // debug.vulkan.layers specifies colon-separated layer names
        char prop[PROPERTY_VALUE_MAX];
        if (!property_get("debug.vulkan.layers", prop, ""))
            return;

        // assign negative/high priorities to them
        int prio = -PROPERTY_VALUE_MAX;

        const char* p = prop;
        const char* delim;
        while ((delim = strchr(p, ':'))) {
            if (delim > p)
                AddImplicitLayer(prio, p, static_cast<size_t>(delim - p));

            prio++;
            p = delim + 1;
        }

        if (p[0] != '\0')
            AddImplicitLayer(prio, p, strlen(p));
    }

    void ParseDebugVulkanLayer() {
        // Checks for consecutive debug.vulkan.layer.<priority> system
        // properties after always checking an initial fixed range.
        static const char prefix[] = "debug.vulkan.layer.";
        static constexpr int kFixedRangeBeginInclusive = 0;
        static constexpr int kFixedRangeEndInclusive = 9;

        bool logged = false;

        int priority = kFixedRangeBeginInclusive;
        while (true) {
            const std::string prop_key =
                std::string(prefix) + std::to_string(priority);
            const std::string prop_val =
                android::base::GetProperty(prop_key, "");

            if (!prop_val.empty()) {
                if (!logged) {
                    ALOGI(
                        "Detected Vulkan layers configured with "
                        "debug.vulkan.layer.<priority>. Checking for "
                        "debug.vulkan.layer.<priority> in the range [%d, %d] "
                        "followed by a consecutive scan.",
                        kFixedRangeBeginInclusive, kFixedRangeEndInclusive);
                    logged = true;
                }
                AddImplicitLayer(priority, prop_val.c_str(), prop_val.length());
            } else if (priority >= kFixedRangeEndInclusive) {
                return;
            }

            ++priority;
        }
    }

    void AddImplicitLayer(int priority, const char* name, size_t len) {
        if (!GrowImplicitLayerArray(1, 0))
            return;

        auto& arr = implicit_layers_;
        auto& layer = arr.elements[arr.count++];

        layer.priority = priority;
        layer.name_offset = AddImplicitLayerName(name, len);

        ALOGV("Added implicit layer %s", GetImplicitLayerName(arr.count - 1));
    }

    size_t AddImplicitLayerName(const char* name, size_t len) {
        if (!GrowImplicitLayerArray(0, len + 1))
            return 0;

        // add the name to the pool
        auto& arr = implicit_layers_;
        size_t offset = arr.pool_size;
        char* dst = arr.name_pool + offset;

        std::copy(name, name + len, dst);
        dst[len] = '\0';

        arr.pool_size += len + 1;

        return offset;
    }

    bool GrowImplicitLayerArray(uint32_t layer_count, size_t name_size) {
        const uint32_t initial_max_count = 16;
        const size_t initial_max_pool_size = 512;

        auto& arr = implicit_layers_;

        // grow the element array if needed
        while (arr.count + layer_count > arr.max_count) {
            uint32_t new_max_count =
                (arr.max_count) ? (arr.max_count << 1) : initial_max_count;
            void* new_mem = nullptr;

            if (new_max_count > arr.max_count) {
                new_mem = allocator_.pfnReallocation(
                    allocator_.pUserData, arr.elements,
                    sizeof(ImplicitLayer) * new_max_count,
                    alignof(ImplicitLayer), scope_);
            }

            if (!new_mem) {
                arr.result = VK_ERROR_OUT_OF_HOST_MEMORY;
                arr.count = 0;
                return false;
            }

            arr.elements = reinterpret_cast<ImplicitLayer*>(new_mem);
            arr.max_count = new_max_count;
        }

        // grow the name pool if needed
        while (arr.pool_size + name_size > arr.max_pool_size) {
            size_t new_max_pool_size = (arr.max_pool_size)
                                           ? (arr.max_pool_size << 1)
                                           : initial_max_pool_size;
            void* new_mem = nullptr;

            if (new_max_pool_size > arr.max_pool_size) {
                new_mem = allocator_.pfnReallocation(
                    allocator_.pUserData, arr.name_pool, new_max_pool_size,
                    alignof(char), scope_);
            }

            if (!new_mem) {
                arr.result = VK_ERROR_OUT_OF_HOST_MEMORY;
                arr.pool_size = 0;
                return false;
            }

            arr.name_pool = reinterpret_cast<char*>(new_mem);
            arr.max_pool_size = new_max_pool_size;
        }

        return true;
    }

    const char* GetImplicitLayerName(uint32_t index) const {
        const auto& arr = implicit_layers_;

        // this may return nullptr when arr.result is not VK_SUCCESS
        return implicit_layers_.name_pool + arr.elements[index].name_offset;
    }

    bool IsImplicitLayer(const char* name) const {
        const auto& arr = implicit_layers_;

        for (uint32_t i = 0; i < arr.count; i++) {
            if (strcmp(name, GetImplicitLayerName(i)) == 0)
                return true;
        }

        return false;
    }

    const char** AllocateNameArray(uint32_t count) const {
        return reinterpret_cast<const char**>(allocator_.pfnAllocation(
            allocator_.pUserData, sizeof(const char*) * count,
            alignof(const char*), scope_));
    }

    const bool is_instance_;
    const VkAllocationCallbacks& allocator_;
    const VkSystemAllocationScope scope_;

    const char** names_;
    uint32_t name_count_;

    ImplicitLayerArray implicit_layers_;
};

// Provide overridden extension names when there are implicit extensions.
// No effect otherwise.
//
// This is used only to enable VK_EXT_debug_report.
class OverrideExtensionNames {
   public:
    OverrideExtensionNames(bool is_instance,
                           const VkAllocationCallbacks& allocator)
        : is_instance_(is_instance),
          allocator_(allocator),
          scope_(VK_SYSTEM_ALLOCATION_SCOPE_COMMAND),
          names_(nullptr),
          name_count_(0),
          install_debug_callback_(false) {}

    ~OverrideExtensionNames() {
        allocator_.pfnFree(allocator_.pUserData, names_);
    }

    VkResult Parse(const char* const* names, uint32_t count) {
        // this is only for debug.vulkan.enable_callback
        if (!EnableDebugCallback())
            return VK_SUCCESS;

        names_ = AllocateNameArray(count + 1);
        if (!names_)
            return VK_ERROR_OUT_OF_HOST_MEMORY;

        std::copy(names, names + count, names_);

        name_count_ = count;
        names_[name_count_++] = "VK_EXT_debug_report";

        install_debug_callback_ = true;

        return VK_SUCCESS;
    }

    const char* const* Names() const { return names_; }

    uint32_t Count() const { return name_count_; }

    bool InstallDebugCallback() const { return install_debug_callback_; }

   private:
    bool EnableDebugCallback() const {
        return (is_instance_ &&
                android::GraphicsEnv::getInstance().isDebuggable() &&
                property_get_bool("debug.vulkan.enable_callback", false));
    }

    const char** AllocateNameArray(uint32_t count) const {
        return reinterpret_cast<const char**>(allocator_.pfnAllocation(
            allocator_.pUserData, sizeof(const char*) * count,
            alignof(const char*), scope_));
    }

    const bool is_instance_;
    const VkAllocationCallbacks& allocator_;
    const VkSystemAllocationScope scope_;

    const char** names_;
    uint32_t name_count_;
    bool install_debug_callback_;
};

// vkCreateInstance and vkCreateDevice helpers with support for layer
// chaining.
class LayerChain {
   public:
    struct ActiveLayer {
        LayerRef ref;
        union {
            VkLayerInstanceLink instance_link;
            VkLayerDeviceLink device_link;
        };
    };

    static VkResult CreateInstance(const VkInstanceCreateInfo* create_info,
                                   const VkAllocationCallbacks* allocator,
                                   VkInstance* instance_out);

    static VkResult CreateDevice(VkPhysicalDevice physical_dev,
                                 const VkDeviceCreateInfo* create_info,
                                 const VkAllocationCallbacks* allocator,
                                 VkDevice* dev_out);

    static void DestroyInstance(VkInstance instance,
                                const VkAllocationCallbacks* allocator);

    static void DestroyDevice(VkDevice dev,
                              const VkAllocationCallbacks* allocator);

    static const ActiveLayer* GetActiveLayers(VkPhysicalDevice physical_dev,
                                              uint32_t& count);

   private:
    LayerChain(bool is_instance,
               const driver::DebugReportLogger& logger,
               const VkAllocationCallbacks& allocator);
    ~LayerChain();

    VkResult ActivateLayers(const char* const* layer_names,
                            uint32_t layer_count,
                            const char* const* extension_names,
                            uint32_t extension_count);
    VkResult ActivateLayers(VkPhysicalDevice physical_dev,
                            const char* const* layer_names,
                            uint32_t layer_count,
                            const char* const* extension_names,
                            uint32_t extension_count);
    ActiveLayer* AllocateLayerArray(uint32_t count) const;
    VkResult LoadLayer(ActiveLayer& layer, const char* name);
    void SetupLayerLinks();

    bool Empty() const;
    void ModifyCreateInfo(VkInstanceCreateInfo& info);
    void ModifyCreateInfo(VkDeviceCreateInfo& info);

    VkResult Create(const VkInstanceCreateInfo* create_info,
                    const VkAllocationCallbacks* allocator,
                    VkInstance* instance_out);

    VkResult Create(VkPhysicalDevice physical_dev,
                    const VkDeviceCreateInfo* create_info,
                    const VkAllocationCallbacks* allocator,
                    VkDevice* dev_out);

    VkResult ValidateExtensions(const char* const* extension_names,
                                uint32_t extension_count);
    VkResult ValidateExtensions(VkPhysicalDevice physical_dev,
                                const char* const* extension_names,
                                uint32_t extension_count);
    VkExtensionProperties* AllocateDriverExtensionArray(uint32_t count) const;
    bool IsLayerExtension(const char* name) const;
    bool IsDriverExtension(const char* name) const;

    template <typename DataType>
    void StealLayers(DataType& data);

    static void DestroyLayers(ActiveLayer* layers,
                              uint32_t count,
                              const VkAllocationCallbacks& allocator);

    static VKAPI_ATTR VkResult SetInstanceLoaderData(VkInstance instance,
                                                     void* object);
    static VKAPI_ATTR VkResult SetDeviceLoaderData(VkDevice device,
                                                   void* object);

    static VKAPI_ATTR VkBool32
    DebugReportCallback(VkDebugReportFlagsEXT flags,
                        VkDebugReportObjectTypeEXT obj_type,
                        uint64_t obj,
                        size_t location,
                        int32_t msg_code,
                        const char* layer_prefix,
                        const char* msg,
                        void* user_data);

    const bool is_instance_;
    const driver::DebugReportLogger& logger_;
    const VkAllocationCallbacks& allocator_;

    OverrideLayerNames override_layers_;
    OverrideExtensionNames override_extensions_;

    ActiveLayer* layers_;
    uint32_t layer_count_;

    PFN_vkGetInstanceProcAddr get_instance_proc_addr_;
    PFN_vkGetDeviceProcAddr get_device_proc_addr_;

    union {
        VkLayerInstanceCreateInfo instance_chain_info_[2];
        VkLayerDeviceCreateInfo device_chain_info_[2];
    };

    VkExtensionProperties* driver_extensions_;
    uint32_t driver_extension_count_;
    std::bitset<driver::ProcHook::EXTENSION_COUNT> enabled_extensions_;
};

LayerChain::LayerChain(bool is_instance,
                       const driver::DebugReportLogger& logger,
                       const VkAllocationCallbacks& allocator)
    : is_instance_(is_instance),
      logger_(logger),
      allocator_(allocator),
      override_layers_(is_instance, allocator),
      override_extensions_(is_instance, allocator),
      layers_(nullptr),
      layer_count_(0),
      get_instance_proc_addr_(nullptr),
      get_device_proc_addr_(nullptr),
      driver_extensions_(nullptr),
      driver_extension_count_(0) {
    // advertise the loader supported core Vulkan API version at vulkan::api
    for (uint32_t i = driver::ProcHook::EXTENSION_CORE_1_0;
         i != driver::ProcHook::EXTENSION_COUNT; ++i) {
        enabled_extensions_.set(i);
    }
}

LayerChain::~LayerChain() {
    allocator_.pfnFree(allocator_.pUserData, driver_extensions_);
    DestroyLayers(layers_, layer_count_, allocator_);
}

/* Activate desired layers  early in
 * vkCreateInstance, activate the desired layers.  Early in vkCreateInstance,
 * activate the desired layers.  Early in vkCreateInstance, activate the desired
 * layers.  Early in vkCreateInstance, activate the desired layers.
 */
VkResult LayerChain::ActivateLayers(const char* const* layer_names,
                                    uint32_t layer_count,
                                    const char* const* extension_names,
                                    uint32_t extension_count) {
    VkResult result = override_layers_.Parse(layer_names, layer_count);
    if (result != VK_SUCCESS)
        return result;

    result = override_extensions_.Parse(extension_names, extension_count);
    if (result != VK_SUCCESS)
        return result;

    if (override_layers_.Count()) {
        layer_names = override_layers_.Names();
        layer_count = override_layers_.Count();
    }

    if (!layer_count) {
        // point head of chain to the driver
        get_instance_proc_addr_ = driver::GetInstanceProcAddr;

        return VK_SUCCESS;
    }

    layers_ = AllocateLayerArray(layer_count);
    if (!layers_)
        return VK_ERROR_OUT_OF_HOST_MEMORY;

    // load layers
    for (uint32_t i = 0; i < layer_count; i++) {
        result = LoadLayer(layers_[i], layer_names[i]);
        if (result != VK_SUCCESS)
            return result;

        // count loaded layers for proper destructions on errors
        layer_count_++;
    }

    SetupLayerLinks();

    return VK_SUCCESS;
}

VkResult LayerChain::ActivateLayers(VkPhysicalDevice physical_dev,
                                    const char* const* layer_names,
                                    uint32_t layer_count,
                                    const char* const* extension_names,
                                    uint32_t extension_count) {
    uint32_t instance_layer_count;
    const ActiveLayer* instance_layers =
        GetActiveLayers(physical_dev, instance_layer_count);

    // log a message if the application device layer array is not empty nor an
    // exact match of the instance layer array.
    if (layer_count) {
        bool exact_match = (instance_layer_count == layer_count);
        if (exact_match) {
            for (uint32_t i = 0; i < instance_layer_count; i++) {
                const Layer& l = *instance_layers[i].ref;
                if (strcmp(GetLayerProperties(l).layerName, layer_names[i])) {
                    exact_match = false;
                    break;
                }
            }
        }

        if (!exact_match) {
            logger_.Warn(physical_dev,
                         "Device layers disagree with instance layers and are "
                         "overridden by instance layers");
        }
    }

    VkResult result =
        override_extensions_.Parse(extension_names, extension_count);
    if (result != VK_SUCCESS)
        return result;

    if (!instance_layer_count) {
        // point head of chain to the driver
        get_instance_proc_addr_ = driver::GetInstanceProcAddr;
        get_device_proc_addr_ = driver::GetDeviceProcAddr;

        return VK_SUCCESS;
    }

    layers_ = AllocateLayerArray(instance_layer_count);
    if (!layers_)
        return VK_ERROR_OUT_OF_HOST_MEMORY;

    for (uint32_t i = 0; i < instance_layer_count; i++) {
        const Layer& l = *instance_layers[i].ref;

        // no need to and cannot chain non-global layers
        if (!IsLayerGlobal(l))
            continue;

        // this never fails
        new (&layers_[layer_count_++]) ActiveLayer{GetLayerRef(l), {}};
    }

    // this may happen when all layers are non-global ones
    if (!layer_count_) {
        get_instance_proc_addr_ = driver::GetInstanceProcAddr;
        get_device_proc_addr_ = driver::GetDeviceProcAddr;
        return VK_SUCCESS;
    }

    SetupLayerLinks();

    return VK_SUCCESS;
}

LayerChain::ActiveLayer* LayerChain::AllocateLayerArray(uint32_t count) const {
    VkSystemAllocationScope scope = (is_instance_)
                                        ? VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE
                                        : VK_SYSTEM_ALLOCATION_SCOPE_COMMAND;

    return reinterpret_cast<ActiveLayer*>(allocator_.pfnAllocation(
        allocator_.pUserData, sizeof(ActiveLayer) * count, alignof(ActiveLayer),
        scope));
}

VkResult LayerChain::LoadLayer(ActiveLayer& layer, const char* name) {
    const Layer* l = FindLayer(name);
    if (!l) {
        logger_.Err(VK_NULL_HANDLE, "Failed to find layer %s", name);
        return VK_ERROR_LAYER_NOT_PRESENT;
    }

    new (&layer) ActiveLayer{GetLayerRef(*l), {}};
    if (!layer.ref) {
        ALOGW("Failed to open layer %s", name);
        layer.ref.~LayerRef();
        return VK_ERROR_LAYER_NOT_PRESENT;
    }

    if (!layer.ref.GetGetInstanceProcAddr()) {
        ALOGW("Failed to locate vkGetInstanceProcAddr in layer %s", name);
        layer.ref.~LayerRef();
        return VK_ERROR_LAYER_NOT_PRESENT;
    }

    ALOGI("Loaded layer %s", name);

    return VK_SUCCESS;
}

void LayerChain::SetupLayerLinks() {
    if (is_instance_) {
        for (uint32_t i = 0; i < layer_count_; i++) {
            ActiveLayer& layer = layers_[i];

            // point head of chain to the first layer
            if (i == 0)
                get_instance_proc_addr_ = layer.ref.GetGetInstanceProcAddr();

            // point tail of chain to the driver
            if (i == layer_count_ - 1) {
                layer.instance_link.pNext = nullptr;
                layer.instance_link.pfnNextGetInstanceProcAddr =
                    driver::GetInstanceProcAddr;
                break;
            }

            const ActiveLayer& next = layers_[i + 1];

            // const_cast as some naughty layers want to modify our links!
            layer.instance_link.pNext =
                const_cast<VkLayerInstanceLink*>(&next.instance_link);
            layer.instance_link.pfnNextGetInstanceProcAddr =
                next.ref.GetGetInstanceProcAddr();
        }
    } else {
        for (uint32_t i = 0; i < layer_count_; i++) {
            ActiveLayer& layer = layers_[i];

            // point head of chain to the first layer
            if (i == 0) {
                get_instance_proc_addr_ = layer.ref.GetGetInstanceProcAddr();
                get_device_proc_addr_ = layer.ref.GetGetDeviceProcAddr();
            }

            // point tail of chain to the driver
            if (i == layer_count_ - 1) {
                layer.device_link.pNext = nullptr;
                layer.device_link.pfnNextGetInstanceProcAddr =
                    driver::GetInstanceProcAddr;
                layer.device_link.pfnNextGetDeviceProcAddr =
                    driver::GetDeviceProcAddr;
                break;
            }

            const ActiveLayer& next = layers_[i + 1];

            // const_cast as some naughty layers want to modify our links!
            layer.device_link.pNext =
                const_cast<VkLayerDeviceLink*>(&next.device_link);
            layer.device_link.pfnNextGetInstanceProcAddr =
                next.ref.GetGetInstanceProcAddr();
            layer.device_link.pfnNextGetDeviceProcAddr =
                next.ref.GetGetDeviceProcAddr();
        }
    }
}

bool LayerChain::Empty() const {
    return (!layer_count_ && !override_layers_.Count() &&
            !override_extensions_.Count());
}

void LayerChain::ModifyCreateInfo(VkInstanceCreateInfo& info) {
    if (layer_count_) {
        auto& link_info = instance_chain_info_[1];
        link_info.sType = VK_STRUCTURE_TYPE_LOADER_INSTANCE_CREATE_INFO;
        link_info.pNext = info.pNext;
        link_info.function = VK_LAYER_FUNCTION_LINK;
        link_info.u.pLayerInfo = &layers_[0].instance_link;

        auto& cb_info = instance_chain_info_[0];
        cb_info.sType = VK_STRUCTURE_TYPE_LOADER_INSTANCE_CREATE_INFO;
        cb_info.pNext = &link_info;
        cb_info.function = VK_LAYER_FUNCTION_DATA_CALLBACK;
        cb_info.u.pfnSetInstanceLoaderData = SetInstanceLoaderData;

        info.pNext = &cb_info;
    }

    if (override_layers_.Count()) {
        info.enabledLayerCount = override_layers_.Count();
        info.ppEnabledLayerNames = override_layers_.Names();
    }

    if (override_extensions_.Count()) {
        info.enabledExtensionCount = override_extensions_.Count();
        info.ppEnabledExtensionNames = override_extensions_.Names();
    }
}

void LayerChain::ModifyCreateInfo(VkDeviceCreateInfo& info) {
    if (layer_count_) {
        auto& link_info = device_chain_info_[1];
        link_info.sType = VK_STRUCTURE_TYPE_LOADER_DEVICE_CREATE_INFO;
        link_info.pNext = info.pNext;
        link_info.function = VK_LAYER_FUNCTION_LINK;
        link_info.u.pLayerInfo = &layers_[0].device_link;

        auto& cb_info = device_chain_info_[0];
        cb_info.sType = VK_STRUCTURE_TYPE_LOADER_DEVICE_CREATE_INFO;
        cb_info.pNext = &link_info;
        cb_info.function = VK_LAYER_FUNCTION_DATA_CALLBACK;
        cb_info.u.pfnSetDeviceLoaderData = SetDeviceLoaderData;

        info.pNext = &cb_info;
    }

    if (override_layers_.Count()) {
        info.enabledLayerCount = override_layers_.Count();
        info.ppEnabledLayerNames = override_layers_.Names();
    }

    if (override_extensions_.Count()) {
        info.enabledExtensionCount = override_extensions_.Count();
        info.ppEnabledExtensionNames = override_extensions_.Names();
    }
}

VkResult LayerChain::Create(const VkInstanceCreateInfo* create_info,
                            const VkAllocationCallbacks* allocator,
                            VkInstance* instance_out) {
    VkResult result = ValidateExtensions(create_info->ppEnabledExtensionNames,
                                         create_info->enabledExtensionCount);
    if (result != VK_SUCCESS)
        return result;

    // call down the chain
    PFN_vkCreateInstance create_instance =
        reinterpret_cast<PFN_vkCreateInstance>(
            get_instance_proc_addr_(VK_NULL_HANDLE, "vkCreateInstance"));
    VkInstance instance;
    result = create_instance(create_info, allocator, &instance);
    if (result != VK_SUCCESS)
        return result;

    // initialize InstanceData
    InstanceData& data = GetData(instance);

    if (!InitDispatchTable(instance, get_instance_proc_addr_,
                           enabled_extensions_)) {
        if (data.dispatch.DestroyInstance)
            data.dispatch.DestroyInstance(instance, allocator);

        return VK_ERROR_INITIALIZATION_FAILED;
    }

    // install debug report callback
    if (override_extensions_.InstallDebugCallback()) {
        PFN_vkCreateDebugReportCallbackEXT create_debug_report_callback =
            reinterpret_cast<PFN_vkCreateDebugReportCallbackEXT>(
                get_instance_proc_addr_(instance,
                                        "vkCreateDebugReportCallbackEXT"));
        data.destroy_debug_callback =
            reinterpret_cast<PFN_vkDestroyDebugReportCallbackEXT>(
                get_instance_proc_addr_(instance,
                                        "vkDestroyDebugReportCallbackEXT"));
        if (!create_debug_report_callback || !data.destroy_debug_callback) {
            ALOGE("Broken VK_EXT_debug_report support");
            data.dispatch.DestroyInstance(instance, allocator);
            return VK_ERROR_INITIALIZATION_FAILED;
        }

        VkDebugReportCallbackCreateInfoEXT debug_callback_info = {};
        debug_callback_info.sType =
            VK_STRUCTURE_TYPE_DEBUG_REPORT_CREATE_INFO_EXT;
        debug_callback_info.flags =
            VK_DEBUG_REPORT_ERROR_BIT_EXT | VK_DEBUG_REPORT_WARNING_BIT_EXT;
        debug_callback_info.pfnCallback = DebugReportCallback;

        VkDebugReportCallbackEXT debug_callback;
        result = create_debug_report_callback(instance, &debug_callback_info,
                                              nullptr, &debug_callback);
        if (result != VK_SUCCESS) {
            ALOGE("Failed to install debug report callback");
            data.dispatch.DestroyInstance(instance, allocator);
            return VK_ERROR_INITIALIZATION_FAILED;
        }

        data.debug_callback = debug_callback;

        ALOGI("Installed debug report callback");
    }

    StealLayers(data);

    *instance_out = instance;

    return VK_SUCCESS;
}

VkResult LayerChain::Create(VkPhysicalDevice physical_dev,
                            const VkDeviceCreateInfo* create_info,
                            const VkAllocationCallbacks* allocator,
                            VkDevice* dev_out) {
    VkResult result =
        ValidateExtensions(physical_dev, create_info->ppEnabledExtensionNames,
                           create_info->enabledExtensionCount);
    if (result != VK_SUCCESS)
        return result;

    // call down the chain
    PFN_vkCreateDevice create_device =
        GetData(physical_dev).dispatch.CreateDevice;
    VkDevice dev;
    result = create_device(physical_dev, create_info, allocator, &dev);
    if (result != VK_SUCCESS)
        return result;

    // initialize DeviceData
    DeviceData& data = GetData(dev);

    if (!InitDispatchTable(dev, get_device_proc_addr_, enabled_extensions_)) {
        if (data.dispatch.DestroyDevice)
            data.dispatch.DestroyDevice(dev, allocator);

        return VK_ERROR_INITIALIZATION_FAILED;
    }

    // no StealLayers so that active layers are destroyed with this
    // LayerChain
    *dev_out = dev;

    return VK_SUCCESS;
}

VkResult LayerChain::ValidateExtensions(const char* const* extension_names,
                                        uint32_t extension_count) {
    if (!extension_count)
        return VK_SUCCESS;

    // query driver instance extensions
    uint32_t count;
    VkResult result =
        EnumerateInstanceExtensionProperties(nullptr, &count, nullptr);
    if (result == VK_SUCCESS && count) {
        driver_extensions_ = AllocateDriverExtensionArray(count);
        result = (driver_extensions_) ? EnumerateInstanceExtensionProperties(
                                            nullptr, &count, driver_extensions_)
                                      : VK_ERROR_OUT_OF_HOST_MEMORY;
    }
    if (result != VK_SUCCESS)
        return result;

    driver_extension_count_ = count;

    for (uint32_t i = 0; i < extension_count; i++) {
        const char* name = extension_names[i];
        if (!IsLayerExtension(name) && !IsDriverExtension(name)) {
            logger_.Err(VK_NULL_HANDLE,
                        "Failed to enable missing instance extension %s", name);
            return VK_ERROR_EXTENSION_NOT_PRESENT;
        }

        auto ext_bit = driver::GetProcHookExtension(name);
        if (ext_bit != driver::ProcHook::EXTENSION_UNKNOWN)
            enabled_extensions_.set(ext_bit);
    }

    return VK_SUCCESS;
}

VkResult LayerChain::ValidateExtensions(VkPhysicalDevice physical_dev,
                                        const char* const* extension_names,
                                        uint32_t extension_count) {
    if (!extension_count)
        return VK_SUCCESS;

    // query driver device extensions
    uint32_t count;
    VkResult result = EnumerateDeviceExtensionProperties(physical_dev, nullptr,
                                                         &count, nullptr);
    if (result == VK_SUCCESS && count) {
        // Work-around a race condition during Android start-up, that can result
        // in the second call to EnumerateDeviceExtensionProperties having
        // another extension.  That causes the second call to return
        // VK_INCOMPLETE.  A work-around is to add 1 to "count" and ask for one
        // more extension property.  See: http://anglebug.com/6715 and
        // internal-to-Google b/206733351.
        count++;
        driver_extensions_ = AllocateDriverExtensionArray(count);
        result = (driver_extensions_)
                     ? EnumerateDeviceExtensionProperties(
                           physical_dev, nullptr, &count, driver_extensions_)
                     : VK_ERROR_OUT_OF_HOST_MEMORY;
    }
    if (result != VK_SUCCESS)
        return result;

    driver_extension_count_ = count;

    for (uint32_t i = 0; i < extension_count; i++) {
        const char* name = extension_names[i];
        if (!IsLayerExtension(name) && !IsDriverExtension(name)) {
            logger_.Err(physical_dev,
                        "Failed to enable missing device extension %s", name);
            return VK_ERROR_EXTENSION_NOT_PRESENT;
        }

        auto ext_bit = driver::GetProcHookExtension(name);
        if (ext_bit != driver::ProcHook::EXTENSION_UNKNOWN)
            enabled_extensions_.set(ext_bit);
    }

    return VK_SUCCESS;
}

VkExtensionProperties* LayerChain::AllocateDriverExtensionArray(
    uint32_t count) const {
    return reinterpret_cast<VkExtensionProperties*>(allocator_.pfnAllocation(
        allocator_.pUserData, sizeof(VkExtensionProperties) * count,
        alignof(VkExtensionProperties), VK_SYSTEM_ALLOCATION_SCOPE_COMMAND));
}

bool LayerChain::IsLayerExtension(const char* name) const {
    if (is_instance_) {
        for (uint32_t i = 0; i < layer_count_; i++) {
            const ActiveLayer& layer = layers_[i];
            if (FindLayerInstanceExtension(*layer.ref, name))
                return true;
        }
    } else {
        for (uint32_t i = 0; i < layer_count_; i++) {
            const ActiveLayer& layer = layers_[i];
            if (FindLayerDeviceExtension(*layer.ref, name))
                return true;
        }
    }

    return false;
}

bool LayerChain::IsDriverExtension(const char* name) const {
    for (uint32_t i = 0; i < driver_extension_count_; i++) {
        if (strcmp(driver_extensions_[i].extensionName, name) == 0)
            return true;
    }

    return false;
}

template <typename DataType>
void LayerChain::StealLayers(DataType& data) {
    data.layers = layers_;
    data.layer_count = layer_count_;

    layers_ = nullptr;
    layer_count_ = 0;
}

void LayerChain::DestroyLayers(ActiveLayer* layers,
                               uint32_t count,
                               const VkAllocationCallbacks& allocator) {
    for (uint32_t i = 0; i < count; i++)
        layers[i].ref.~LayerRef();

    allocator.pfnFree(allocator.pUserData, layers);
}

VkResult LayerChain::SetInstanceLoaderData(VkInstance instance, void* object) {
    driver::InstanceDispatchable dispatchable =
        reinterpret_cast<driver::InstanceDispatchable>(object);

    return (driver::SetDataInternal(dispatchable, &driver::GetData(instance)))
               ? VK_SUCCESS
               : VK_ERROR_INITIALIZATION_FAILED;
}

VkResult LayerChain::SetDeviceLoaderData(VkDevice device, void* object) {
    driver::DeviceDispatchable dispatchable =
        reinterpret_cast<driver::DeviceDispatchable>(object);

    return (driver::SetDataInternal(dispatchable, &driver::GetData(device)))
               ? VK_SUCCESS
               : VK_ERROR_INITIALIZATION_FAILED;
}

VkBool32 LayerChain::DebugReportCallback(VkDebugReportFlagsEXT flags,
                                         VkDebugReportObjectTypeEXT obj_type,
                                         uint64_t obj,
                                         size_t location,
                                         int32_t msg_code,
                                         const char* layer_prefix,
                                         const char* msg,
                                         void* user_data) {
    int prio;

    if (flags & VK_DEBUG_REPORT_ERROR_BIT_EXT)
        prio = ANDROID_LOG_ERROR;
    else if (flags & (VK_DEBUG_REPORT_WARNING_BIT_EXT |
                      VK_DEBUG_REPORT_PERFORMANCE_WARNING_BIT_EXT))
        prio = ANDROID_LOG_WARN;
    else if (flags & VK_DEBUG_REPORT_INFORMATION_BIT_EXT)
        prio = ANDROID_LOG_INFO;
    else if (flags & VK_DEBUG_REPORT_DEBUG_BIT_EXT)
        prio = ANDROID_LOG_DEBUG;
    else
        prio = ANDROID_LOG_UNKNOWN;

    LOG_PRI(prio, LOG_TAG, "[%s] Code %d : %s", layer_prefix, msg_code, msg);

    (void)obj_type;
    (void)obj;
    (void)location;
    (void)user_data;

    return false;
}

/* The loader's actual implementation of vkCreateInstance.  Since the loader is
 * the instance (recognized during the specification of Vulkan 1.1), the primary
 * activity is activating the desired layers, building the layer stack (a chain
 * of all Vulkan API functions from the loader's trampoline function, through
 * any layer functions, and down to the driver).
 */
VkResult LayerChain::CreateInstance(const VkInstanceCreateInfo* create_info,
                                    const VkAllocationCallbacks* allocator,
                                    VkInstance* instance_out) {
    const driver::DebugReportLogger logger(*create_info);
    LayerChain chain(true, logger,
                     (allocator) ? *allocator : driver::GetDefaultAllocator());

    VkResult result = chain.ActivateLayers(create_info->ppEnabledLayerNames,
                                           create_info->enabledLayerCount,
                                           create_info->ppEnabledExtensionNames,
                                           create_info->enabledExtensionCount);
    if (result != VK_SUCCESS)
        return result;

    // use a local create info when the chain is not empty
    VkInstanceCreateInfo local_create_info;
    if (!chain.Empty()) {
        local_create_info = *create_info;
        chain.ModifyCreateInfo(local_create_info);
        create_info = &local_create_info;
    }

    return chain.Create(create_info, allocator, instance_out);
}

VkResult LayerChain::CreateDevice(VkPhysicalDevice physical_dev,
                                  const VkDeviceCreateInfo* create_info,
                                  const VkAllocationCallbacks* allocator,
                                  VkDevice* dev_out) {
    const driver::DebugReportLogger logger = driver::Logger(physical_dev);
    LayerChain chain(
        false, logger,
        (allocator) ? *allocator : driver::GetData(physical_dev).allocator);

    VkResult result = chain.ActivateLayers(
        physical_dev, create_info->ppEnabledLayerNames,
        create_info->enabledLayerCount, create_info->ppEnabledExtensionNames,
        create_info->enabledExtensionCount);
    if (result != VK_SUCCESS)
        return result;

    // use a local create info when the chain is not empty
    VkDeviceCreateInfo local_create_info;
    if (!chain.Empty()) {
        local_create_info = *create_info;
        chain.ModifyCreateInfo(local_create_info);
        create_info = &local_create_info;
    }

    return chain.Create(physical_dev, create_info, allocator, dev_out);
}

void LayerChain::DestroyInstance(VkInstance instance,
                                 const VkAllocationCallbacks* allocator) {
    InstanceData& data = GetData(instance);

    if (data.debug_callback != VK_NULL_HANDLE)
        data.destroy_debug_callback(instance, data.debug_callback, allocator);

    ActiveLayer* layers = reinterpret_cast<ActiveLayer*>(data.layers);
    uint32_t layer_count = data.layer_count;

    VkAllocationCallbacks local_allocator;
    if (!allocator)
        local_allocator = driver::GetData(instance).allocator;

    // this also destroys InstanceData
    data.dispatch.DestroyInstance(instance, allocator);

    DestroyLayers(layers, layer_count,
                  (allocator) ? *allocator : local_allocator);
}

void LayerChain::DestroyDevice(VkDevice device,
                               const VkAllocationCallbacks* allocator) {
    DeviceData& data = GetData(device);
    // this also destroys DeviceData
    data.dispatch.DestroyDevice(device, allocator);
}

const LayerChain::ActiveLayer* LayerChain::GetActiveLayers(
    VkPhysicalDevice physical_dev,
    uint32_t& count) {
    count = GetData(physical_dev).layer_count;
    return reinterpret_cast<const ActiveLayer*>(GetData(physical_dev).layers);
}

// ----------------------------------------------------------------------------

/* This function is called by the following early Vulkan API functions, in order
 * to make sure that the driver and any layers are discovered and loaded:
 *
 * - EnumerateInstanceVersion
 * - EnumerateInstanceLayerProperties
 * - EnumerateInstanceExtensionProperties
 * - CreateInstance
 */
bool EnsureInitialized() {
    static bool initialized = false;
    static pid_t init_attempted_for_pid = 0;
    static std::mutex init_lock;

    std::lock_guard<std::mutex> lock(init_lock);
    if (init_attempted_for_pid == getpid())
        return initialized;

    init_attempted_for_pid = getpid();
    if (driver::OpenHAL()) {
        DiscoverLayers();
        initialized = true;
    }

    return initialized;
}

template <typename Functor>
void ForEachLayerFromSettings(Functor functor) {
    const std::string layersSetting =
        android::GraphicsEnv::getInstance().getDebugLayers();
    if (!layersSetting.empty()) {
        std::vector<std::string> layers =
            android::base::Split(layersSetting, ":");
        for (uint32_t i = 0; i < layers.size(); i++) {
            const Layer* layer = FindLayer(layers[i].c_str());
            if (!layer) {
                continue;
            }
            functor(layer);
        }
    }
}

}  // anonymous namespace

/* The loader's entry point for vkCreateInstance, which ensures that the loader
 * is initialized and then uses LayerChain::CreateInstance to do the actual
 * work.
 */
VkResult CreateInstance(const VkInstanceCreateInfo* pCreateInfo,
                        const VkAllocationCallbacks* pAllocator,
                        VkInstance* pInstance) {
    ATRACE_CALL();

    if (!EnsureInitialized())
        return VK_ERROR_INITIALIZATION_FAILED;

    return LayerChain::CreateInstance(pCreateInfo, pAllocator, pInstance);
}

void DestroyInstance(VkInstance instance,
                     const VkAllocationCallbacks* pAllocator) {
    ATRACE_CALL();

    if (instance != VK_NULL_HANDLE)
        LayerChain::DestroyInstance(instance, pAllocator);
}

VkResult CreateDevice(VkPhysicalDevice physicalDevice,
                      const VkDeviceCreateInfo* pCreateInfo,
                      const VkAllocationCallbacks* pAllocator,
                      VkDevice* pDevice) {
    ATRACE_CALL();

    return LayerChain::CreateDevice(physicalDevice, pCreateInfo, pAllocator,
                                    pDevice);
}

void DestroyDevice(VkDevice device, const VkAllocationCallbacks* pAllocator) {
    ATRACE_CALL();

    if (device != VK_NULL_HANDLE)
        LayerChain::DestroyDevice(device, pAllocator);
}

/* The implementation of vkEnumerateInstanceLayerProperties.  As expected, all
 * explicit layers are returned to the application.  For compatibility with the
 * LunarG loader, all implicit layers are also returned to the application, even
 * though implicit layers are enabled without application involvement.  No
 * platform or OEM layers are returned, as those layers are enabled without
 * application knowledge or involvement.
 */
VkResult EnumerateInstanceLayerProperties(uint32_t* pPropertyCount,
                                          VkLayerProperties* pProperties) {
    ATRACE_CALL();

    if (!EnsureInitialized())
        return VK_ERROR_OUT_OF_HOST_MEMORY;

    // NOTE: GetEnumeratedLayerCount relies on all IMPLICIT and EXPLICIT Layer's
    // being added to g_instance_layers before any PLATFORM or OEM Layer's.
    uint32_t count = GetEnumeratedLayerCount();

    if (!pProperties) {
        *pPropertyCount = count;
        return VK_SUCCESS;
    }

    uint32_t copied = std::min(*pPropertyCount, count);
    for (uint32_t i = 0; i < copied; i++) {
        pProperties[i] = GetLayerProperties(GetLayer(i));
    }
    *pPropertyCount = copied;

    return (copied == count) ? VK_SUCCESS : VK_INCOMPLETE;
}

/* The loader's "instance" implementation of
 * vkEnumerateInstanceExtensionProperties (see "driver.cpp" for the loader's
 * "device" implementation).  All instance extensions from all layers are
 * returned to the application, in addition to the loader's instance extensions.
 *
 * TODO: is it true that all instance extensions from all layers are returned?
 * It won't work if an application tries to enable an instance extension from a
 * layer that isn't given to vkCreateInstance.
 */
VkResult EnumerateInstanceExtensionProperties(
    const char* pLayerName,
    uint32_t* pPropertyCount,
    VkExtensionProperties* pProperties) {
    ATRACE_CALL();

    if (!EnsureInitialized())
        return VK_ERROR_OUT_OF_HOST_MEMORY;

    if (pLayerName) {
        const Layer* layer = FindLayer(pLayerName);
        if (!layer)
            return VK_ERROR_LAYER_NOT_PRESENT;

        uint32_t count;
        const VkExtensionProperties* props =
            GetLayerInstanceExtensions(*layer, count);

        if (!pProperties || *pPropertyCount > count)
            *pPropertyCount = count;
        if (pProperties)
            std::copy(props, props + *pPropertyCount, pProperties);

        return *pPropertyCount < count ? VK_INCOMPLETE : VK_SUCCESS;
    }

    // If the pLayerName is nullptr, we must advertise all instance extensions
    // from all implicitly enabled layers and the driver implementation. If
    // there are duplicates among layers and the driver implementation, always
    // only preserve the top layer closest to the application regardless of the
    // spec version.
    std::vector<VkExtensionProperties> properties;
    std::unordered_set<std::string> extensionNames;

    // Expose extensions from implicitly enabled layers.
    ForEachLayerFromSettings([&](const Layer* layer) {
        uint32_t count = 0;
        const VkExtensionProperties* props =
            GetLayerInstanceExtensions(*layer, count);
        if (count > 0) {
            for (uint32_t i = 0; i < count; ++i) {
                if (extensionNames.emplace(props[i].extensionName).second) {
                    properties.push_back(props[i]);
                }
            }
        }
    });

    // Expose extensions from driver implementation.
    {
        uint32_t count = 0;
        VkResult result = vulkan::driver::EnumerateInstanceExtensionProperties(
            nullptr, &count, nullptr);
        if (result == VK_SUCCESS && count > 0) {
            std::vector<VkExtensionProperties> props(count);
            result = vulkan::driver::EnumerateInstanceExtensionProperties(
                nullptr, &count, props.data());
            for (auto prop : props) {
                if (extensionNames.emplace(prop.extensionName).second) {
                    properties.push_back(prop);
                }
            }
        }
    }

    uint32_t totalCount = properties.size();
    if (!pProperties || *pPropertyCount > totalCount) {
        *pPropertyCount = totalCount;
    }
    if (pProperties) {
        std::copy(properties.data(), properties.data() + *pPropertyCount,
                  pProperties);
    }
    return *pPropertyCount < totalCount ? VK_INCOMPLETE : VK_SUCCESS;
}

VkResult EnumerateDeviceLayerProperties(VkPhysicalDevice physicalDevice,
                                        uint32_t* pPropertyCount,
                                        VkLayerProperties* pProperties) {
    ATRACE_CALL();

    uint32_t count;
    const LayerChain::ActiveLayer* layers =
        LayerChain::GetActiveLayers(physicalDevice, count);

    if (!pProperties) {
        *pPropertyCount = count;
        return VK_SUCCESS;
    }

    uint32_t copied = std::min(*pPropertyCount, count);
    for (uint32_t i = 0; i < copied; i++)
        pProperties[i] = GetLayerProperties(*layers[i].ref);
    *pPropertyCount = copied;

    return (copied == count) ? VK_SUCCESS : VK_INCOMPLETE;
}

VkResult EnumerateDeviceExtensionProperties(
    VkPhysicalDevice physicalDevice,
    const char* pLayerName,
    uint32_t* pPropertyCount,
    VkExtensionProperties* pProperties) {
    ATRACE_CALL();

    if (pLayerName) {
        // EnumerateDeviceLayerProperties enumerates active layers for
        // backward compatibility.  The extension query here should work for
        // all layers.
        const Layer* layer = FindLayer(pLayerName);
        if (!layer)
            return VK_ERROR_LAYER_NOT_PRESENT;

        uint32_t count;
        const VkExtensionProperties* props =
            GetLayerDeviceExtensions(*layer, count);

        if (!pProperties || *pPropertyCount > count)
            *pPropertyCount = count;
        if (pProperties)
            std::copy(props, props + *pPropertyCount, pProperties);

        return *pPropertyCount < count ? VK_INCOMPLETE : VK_SUCCESS;
    }

    // If the pLayerName is nullptr, we must advertise all device extensions
    // from all implicitly enabled layers and the driver implementation. If
    // there are duplicates among layers and the driver implementation, always
    // only preserve the top layer closest to the application regardless of the
    // spec version.
    std::vector<VkExtensionProperties> properties;
    std::unordered_set<std::string> extensionNames;

    // Expose extensions from implicitly enabled layers.
    ForEachLayerFromSettings([&](const Layer* layer) {
        uint32_t count = 0;
        const VkExtensionProperties* props =
            GetLayerDeviceExtensions(*layer, count);
        if (count > 0) {
            for (uint32_t i = 0; i < count; ++i) {
                if (extensionNames.emplace(props[i].extensionName).second) {
                    properties.push_back(props[i]);
                }
            }
        }
    });

    // Expose extensions from driver implementation.
    {
        const InstanceData& data = GetData(physicalDevice);
        uint32_t count = 0;
        VkResult result = data.dispatch.EnumerateDeviceExtensionProperties(
            physicalDevice, nullptr, &count, nullptr);
        if (result == VK_SUCCESS && count > 0) {
            std::vector<VkExtensionProperties> props(count);
            result = data.dispatch.EnumerateDeviceExtensionProperties(
                physicalDevice, nullptr, &count, props.data());
            for (auto prop : props) {
                if (extensionNames.emplace(prop.extensionName).second) {
                    properties.push_back(prop);
                }
            }
        }
    }

    uint32_t totalCount = properties.size();
    if (!pProperties || *pPropertyCount > totalCount) {
        *pPropertyCount = totalCount;
    }
    if (pProperties) {
        std::copy(properties.data(), properties.data() + *pPropertyCount,
                  pProperties);
    }
    return *pPropertyCount < totalCount ? VK_INCOMPLETE : VK_SUCCESS;
}

VkResult EnumerateInstanceVersion(uint32_t* pApiVersion) {
    ATRACE_CALL();

    // Load the driver here if not done yet. This api will be used in Zygote
    // for Vulkan driver pre-loading because of the minimum overhead.
    if (!EnsureInitialized())
        return VK_ERROR_OUT_OF_HOST_MEMORY;

    *pApiVersion = VK_API_VERSION_1_4;
    return VK_SUCCESS;
}

}  // namespace api
}  // namespace vulkan