loader/loader.c

/*
 *
 * Copyright (c) 2014-2017 The Khronos Group Inc.
 * Copyright (c) 2014-2017 Valve Corporation
 * Copyright (c) 2014-2017 LunarG, Inc.
 * Copyright (C) 2015 Google Inc.
 *
 * 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.

 *
 * Author: Jon Ashburn <jon@lunarg.com>
 * Author: Courtney Goeltzenleuchter <courtney@LunarG.com>
 * Author: Mark Young <marky@lunarg.com>
 *
 */

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stdbool.h>
#include <string.h>
#include <stddef.h>

#include <sys/types.h>
#if defined(_WIN32)
#include "dirent_on_windows.h"
#else  // _WIN32
#include <dirent.h>
#endif  // _WIN32
#include "vk_loader_platform.h"
#include "loader.h"
#include "gpa_helper.h"
#include "table_ops.h"
#include "debug_report.h"
#include "wsi.h"
#include "extensions.h"
#include "vulkan/vk_icd.h"
#include "cJSON.h"
#include "murmurhash.h"

#if defined(__GNUC__)
#if (__GLIBC__ < 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ < 17))
#define secure_getenv __secure_getenv
#endif
#endif

struct loader_struct loader = {0};
// TLS for instance for alloc/free callbacks
THREAD_LOCAL_DECL struct loader_instance *tls_instance;

static size_t loader_platform_combine_path(char *dest, size_t len, ...);

struct loader_phys_dev_per_icd {
    uint32_t count;
    VkPhysicalDevice *phys_devs;
    struct loader_icd_term *this_icd_term;
};

enum loader_debug {
    LOADER_INFO_BIT = 0x01,
    LOADER_WARN_BIT = 0x02,
    LOADER_PERF_BIT = 0x04,
    LOADER_ERROR_BIT = 0x08,
    LOADER_DEBUG_BIT = 0x10,
};

uint32_t g_loader_debug = 0;
uint32_t g_loader_log_msgs = 0;

// thread safety lock for accessing global data structures such as "loader"
// all entrypoints on the instance chain need to be locked except GPA
// additionally CreateDevice and DestroyDevice needs to be locked
loader_platform_thread_mutex loader_lock;
loader_platform_thread_mutex loader_json_lock;

const char *std_validation_str = "VK_LAYER_LUNARG_standard_validation";

// This table contains the loader's instance dispatch table, which contains
// default functions if no instance layers are activated.  This contains
// pointers to "terminator functions".
const VkLayerInstanceDispatchTable instance_disp = {
    .GetInstanceProcAddr = vkGetInstanceProcAddr,
    .DestroyInstance = terminator_DestroyInstance,
    .EnumeratePhysicalDevices = terminator_EnumeratePhysicalDevices,
    .GetPhysicalDeviceFeatures = terminator_GetPhysicalDeviceFeatures,
    .GetPhysicalDeviceFormatProperties = terminator_GetPhysicalDeviceFormatProperties,
    .GetPhysicalDeviceImageFormatProperties = terminator_GetPhysicalDeviceImageFormatProperties,
    .GetPhysicalDeviceProperties = terminator_GetPhysicalDeviceProperties,
    .GetPhysicalDeviceQueueFamilyProperties = terminator_GetPhysicalDeviceQueueFamilyProperties,
    .GetPhysicalDeviceMemoryProperties = terminator_GetPhysicalDeviceMemoryProperties,
    .EnumerateDeviceExtensionProperties = terminator_EnumerateDeviceExtensionProperties,
    .EnumerateDeviceLayerProperties = terminator_EnumerateDeviceLayerProperties,
    .GetPhysicalDeviceSparseImageFormatProperties = terminator_GetPhysicalDeviceSparseImageFormatProperties,
    .DestroySurfaceKHR = terminator_DestroySurfaceKHR,
    .GetPhysicalDeviceSurfaceSupportKHR = terminator_GetPhysicalDeviceSurfaceSupportKHR,
    .GetPhysicalDeviceSurfaceCapabilitiesKHR = terminator_GetPhysicalDeviceSurfaceCapabilitiesKHR,
    .GetPhysicalDeviceSurfaceFormatsKHR = terminator_GetPhysicalDeviceSurfaceFormatsKHR,
    .GetPhysicalDeviceSurfacePresentModesKHR = terminator_GetPhysicalDeviceSurfacePresentModesKHR,
#ifdef VK_USE_PLATFORM_MIR_KHR
    .CreateMirSurfaceKHR = terminator_CreateMirSurfaceKHR,
    .GetPhysicalDeviceMirPresentationSupportKHR = terminator_GetPhysicalDeviceMirPresentationSupportKHR,
#endif
#ifdef VK_USE_PLATFORM_WAYLAND_KHR
    .CreateWaylandSurfaceKHR = terminator_CreateWaylandSurfaceKHR,
    .GetPhysicalDeviceWaylandPresentationSupportKHR = terminator_GetPhysicalDeviceWaylandPresentationSupportKHR,
#endif
#ifdef VK_USE_PLATFORM_WIN32_KHR
    .CreateWin32SurfaceKHR = terminator_CreateWin32SurfaceKHR,
    .GetPhysicalDeviceWin32PresentationSupportKHR = terminator_GetPhysicalDeviceWin32PresentationSupportKHR,
#endif
#ifdef VK_USE_PLATFORM_XCB_KHR
    .CreateXcbSurfaceKHR = terminator_CreateXcbSurfaceKHR,
    .GetPhysicalDeviceXcbPresentationSupportKHR = terminator_GetPhysicalDeviceXcbPresentationSupportKHR,
#endif
#ifdef VK_USE_PLATFORM_XLIB_KHR
    .CreateXlibSurfaceKHR = terminator_CreateXlibSurfaceKHR,
    .GetPhysicalDeviceXlibPresentationSupportKHR = terminator_GetPhysicalDeviceXlibPresentationSupportKHR,
#endif
#ifdef VK_USE_PLATFORM_ANDROID_KHR
    .CreateAndroidSurfaceKHR = terminator_CreateAndroidSurfaceKHR,
#endif
    .GetPhysicalDeviceDisplayPropertiesKHR = terminator_GetPhysicalDeviceDisplayPropertiesKHR,
    .GetPhysicalDeviceDisplayPlanePropertiesKHR = terminator_GetPhysicalDeviceDisplayPlanePropertiesKHR,
    .GetDisplayPlaneSupportedDisplaysKHR = terminator_GetDisplayPlaneSupportedDisplaysKHR,
    .GetDisplayModePropertiesKHR = terminator_GetDisplayModePropertiesKHR,
    .CreateDisplayModeKHR = terminator_CreateDisplayModeKHR,
    .GetDisplayPlaneCapabilitiesKHR = terminator_GetDisplayPlaneCapabilitiesKHR,
    .CreateDisplayPlaneSurfaceKHR = terminator_CreateDisplayPlaneSurfaceKHR,

    // KHR_get_physical_device_properties2
    .GetPhysicalDeviceFeatures2KHR = terminator_GetPhysicalDeviceFeatures2KHR,
    .GetPhysicalDeviceProperties2KHR = terminator_GetPhysicalDeviceProperties2KHR,
    .GetPhysicalDeviceFormatProperties2KHR = terminator_GetPhysicalDeviceFormatProperties2KHR,
    .GetPhysicalDeviceImageFormatProperties2KHR = terminator_GetPhysicalDeviceImageFormatProperties2KHR,
    .GetPhysicalDeviceQueueFamilyProperties2KHR = terminator_GetPhysicalDeviceQueueFamilyProperties2KHR,
    .GetPhysicalDeviceMemoryProperties2KHR = terminator_GetPhysicalDeviceMemoryProperties2KHR,
    .GetPhysicalDeviceSparseImageFormatProperties2KHR = terminator_GetPhysicalDeviceSparseImageFormatProperties2KHR,

#ifdef VK_USE_PLATFORM_XLIB_XRANDR_EXT
    // EXT_acquire_xlib_display
    .AcquireXlibDisplayEXT = terminator_AcquireXlibDisplayEXT,
    .GetRandROutputDisplayEXT = terminator_GetRandROutputDisplayEXT,
#endif

    // EXT_debug_report
    .CreateDebugReportCallbackEXT = terminator_CreateDebugReportCallback,
    .DestroyDebugReportCallbackEXT = terminator_DestroyDebugReportCallback,
    .DebugReportMessageEXT = terminator_DebugReportMessage,

    // EXT_direct_mode_display
    .ReleaseDisplayEXT = terminator_ReleaseDisplayEXT,

    // EXT_display_surface_counter
    .GetPhysicalDeviceSurfaceCapabilities2EXT = terminator_GetPhysicalDeviceSurfaceCapabilities2EXT,

    // NV_external_memory_capabilities
    .GetPhysicalDeviceExternalImageFormatPropertiesNV = terminator_GetPhysicalDeviceExternalImageFormatPropertiesNV,

    // NVX_device_generated_commands
    .GetPhysicalDeviceGeneratedCommandsPropertiesNVX = terminator_GetPhysicalDeviceGeneratedCommandsPropertiesNVX,
};

// A null-terminated list of all of the instance extensions supported by the
// loader
static const char *const LOADER_INSTANCE_EXTENSIONS[] = {VK_KHR_SURFACE_EXTENSION_NAME,
                                                         VK_KHR_DISPLAY_EXTENSION_NAME,
#ifdef VK_USE_PLATFORM_XLIB_KHR
                                                         VK_KHR_XLIB_SURFACE_EXTENSION_NAME,
#endif
#ifdef VK_USE_PLATFORM_XCB_KHR
                                                         VK_KHR_XCB_SURFACE_EXTENSION_NAME,
#endif
#ifdef VK_USE_PLATFORM_WAYLAND_KHR
                                                         VK_KHR_WAYLAND_SURFACE_EXTENSION_NAME,
#endif
#ifdef VK_USE_PLATFORM_MIR_KHR
                                                         VK_KHR_MIR_SURFACE_EXTENSION_NAME,
#endif
#ifdef VK_USE_PLATFORM_ANDROID_KHR
                                                         VK_KHR_ANDROID_SURFACE_EXTENSION_NAME,
#endif
#ifdef VK_USE_PLATFORM_WIN32_KHR
                                                         VK_KHR_WIN32_SURFACE_EXTENSION_NAME,
#endif
                                                         VK_KHR_GET_PHYSICAL_DEVICE_PROPERTIES_2_EXTENSION_NAME,
#ifdef VK_USE_PLATFORM_XLIB_XRANDR_EXT
                                                         VK_EXT_ACQUIRE_XLIB_DISPLAY_EXTENSION_NAME,
#endif
                                                         VK_EXT_DEBUG_REPORT_EXTENSION_NAME,
                                                         VK_EXT_DIRECT_MODE_DISPLAY_EXTENSION_NAME,
                                                         VK_EXT_DISPLAY_SURFACE_COUNTER_EXTENSION_NAME,
                                                         VK_EXT_VALIDATION_FLAGS_EXTENSION_NAME,
#ifdef VK_USE_PLATFORM_VI_NN
                                                         VK_NN_VI_SURFACE_EXTENSION_NAME,
#endif
                                                         VK_NV_EXTERNAL_MEMORY_CAPABILITIES_EXTENSION_NAME,
                                                         NULL};

LOADER_PLATFORM_THREAD_ONCE_DECLARATION(once_init);

void *loader_instance_heap_alloc(const struct loader_instance *instance, size_t size, VkSystemAllocationScope alloc_scope) {
    void *pMemory = NULL;
#if (DEBUG_DISABLE_APP_ALLOCATORS == 1)
    {
#else
    if (instance && instance->alloc_callbacks.pfnAllocation) {
        /* These are internal structures, so it's best to align everything to
         * the largest unit size which is the size of a uint64_t.
        */
        pMemory = instance->alloc_callbacks.pfnAllocation(instance->alloc_callbacks.pUserData, size, sizeof(uint64_t), alloc_scope);
    } else {
#endif
        pMemory = malloc(size);
    }
    return pMemory;
}

void loader_instance_heap_free(const struct loader_instance *instance, void *pMemory) {
    if (pMemory != NULL) {
#if (DEBUG_DISABLE_APP_ALLOCATORS == 1)
        {
#else
        if (instance && instance->alloc_callbacks.pfnFree) {
            instance->alloc_callbacks.pfnFree(instance->alloc_callbacks.pUserData, pMemory);
        } else {
#endif
            free(pMemory);
        }
    }
}

void *loader_instance_heap_realloc(const struct loader_instance *instance, void *pMemory, size_t orig_size, size_t size,
                                   VkSystemAllocationScope alloc_scope) {
    void *pNewMem = NULL;
    if (pMemory == NULL || orig_size == 0) {
        pNewMem = loader_instance_heap_alloc(instance, size, alloc_scope);
    } else if (size == 0) {
        loader_instance_heap_free(instance, pMemory);
#if (DEBUG_DISABLE_APP_ALLOCATORS == 1)
#else
    } else if (instance && instance->alloc_callbacks.pfnReallocation) {
        /* These are internal structures, so it's best to align everything to
         * the largest unit size which is the size of a uint64_t.
         */
        pNewMem = instance->alloc_callbacks.pfnReallocation(instance->alloc_callbacks.pUserData, pMemory, size, sizeof(uint64_t),
                                                            alloc_scope);
#endif
    } else {
        pNewMem = realloc(pMemory, size);
    }
    return pNewMem;
}

void *loader_instance_tls_heap_alloc(size_t size) {
    return loader_instance_heap_alloc(tls_instance, size, VK_SYSTEM_ALLOCATION_SCOPE_COMMAND);
}

void loader_instance_tls_heap_free(void *pMemory) { loader_instance_heap_free(tls_instance, pMemory); }

void *loader_device_heap_alloc(const struct loader_device *device, size_t size, VkSystemAllocationScope alloc_scope) {
    void *pMemory = NULL;
#if (DEBUG_DISABLE_APP_ALLOCATORS == 1)
    {
#else
    if (device && device->alloc_callbacks.pfnAllocation) {
        /* These are internal structures, so it's best to align everything to
         * the largest unit size which is the size of a uint64_t.
        */
        pMemory = device->alloc_callbacks.pfnAllocation(device->alloc_callbacks.pUserData, size, sizeof(uint64_t), alloc_scope);
    } else {
#endif
        pMemory = malloc(size);
    }
    return pMemory;
}

void loader_device_heap_free(const struct loader_device *device, void *pMemory) {
    if (pMemory != NULL) {
#if (DEBUG_DISABLE_APP_ALLOCATORS == 1)
        {
#else
        if (device && device->alloc_callbacks.pfnFree) {
            device->alloc_callbacks.pfnFree(device->alloc_callbacks.pUserData, pMemory);
        } else {
#endif
            free(pMemory);
        }
    }
}

void *loader_device_heap_realloc(const struct loader_device *device, void *pMemory, size_t orig_size, size_t size,
                                 VkSystemAllocationScope alloc_scope) {
    void *pNewMem = NULL;
    if (pMemory == NULL || orig_size == 0) {
        pNewMem = loader_device_heap_alloc(device, size, alloc_scope);
    } else if (size == 0) {
        loader_device_heap_free(device, pMemory);
#if (DEBUG_DISABLE_APP_ALLOCATORS == 1)
#else
    } else if (device && device->alloc_callbacks.pfnReallocation) {
        /* These are internal structures, so it's best to align everything to
         * the largest unit size which is the size of a uint64_t.
        */
        pNewMem = device->alloc_callbacks.pfnReallocation(device->alloc_callbacks.pUserData, pMemory, size, sizeof(uint64_t),
                                                          alloc_scope);
#endif
    } else {
        pNewMem = realloc(pMemory, size);
    }
    return pNewMem;
}

// Environment variables
#if defined(__linux__)

static inline char *loader_getenv(const char *name, const struct loader_instance *inst) {
    // No allocation of memory necessary for Linux, but we should at least touch
    // the inst pointer to get rid of compiler warnings.
    (void)inst;
    return getenv(name);
}
static inline void loader_free_getenv(char *val, const struct loader_instance *inst) {
    // No freeing of memory necessary for Linux, but we should at least touch
    // the val and inst pointers to get rid of compiler warnings.
    (void)val;
    (void)inst;
}

#elif defined(WIN32)

static inline char *loader_getenv(const char *name, const struct loader_instance *inst) {
    char *retVal;
    DWORD valSize;

    valSize = GetEnvironmentVariableA(name, NULL, 0);

    // valSize DOES include the null terminator, so for any set variable
    // will always be at least 1. If it's 0, the variable wasn't set.
    if (valSize == 0) return NULL;

    // Allocate the space necessary for the registry entry
    if (NULL != inst && NULL != inst->alloc_callbacks.pfnAllocation) {
        retVal = (char *)inst->alloc_callbacks.pfnAllocation(inst->alloc_callbacks.pUserData, valSize, sizeof(char *),
                                                             VK_SYSTEM_ALLOCATION_SCOPE_COMMAND);
    } else {
        retVal = (char *)malloc(valSize);
    }

    if (NULL != retVal) {
        GetEnvironmentVariableA(name, retVal, valSize);
    }

    return retVal;
}

static inline void loader_free_getenv(char *val, const struct loader_instance *inst) {
    if (NULL != inst && NULL != inst->alloc_callbacks.pfnFree) {
        inst->alloc_callbacks.pfnFree(inst->alloc_callbacks.pUserData, val);
    } else {
        free((void *)val);
    }
}

#else

static inline char *loader_getenv(const char *name, const struct loader_instance *inst) {
    // stub func
    (void)inst;
    (void)name;
    return NULL;
}
static inline void loader_free_getenv(char *val, const struct loader_instance *inst) {
    // stub func
    (void)val;
    (void)inst;
}

#endif

void loader_log(const struct loader_instance *inst, VkFlags msg_type, int32_t msg_code, const char *format, ...) {
    char msg[512];
    char cmd_line_msg[512];
    uint16_t cmd_line_size = sizeof(cmd_line_msg);
    va_list ap;
    int ret;

    va_start(ap, format);
    ret = vsnprintf(msg, sizeof(msg), format, ap);
    if ((ret >= (int)sizeof(msg)) || ret < 0) {
        msg[sizeof(msg) - 1] = '\0';
    }
    va_end(ap);

    if (inst) {
        util_DebugReportMessage(inst, msg_type, VK_DEBUG_REPORT_OBJECT_TYPE_INSTANCE_EXT, (uint64_t)(uintptr_t)inst, 0, msg_code,
                                "loader", msg);
    }

    if (!(msg_type & g_loader_log_msgs)) {
        return;
    }

    cmd_line_msg[0] = '\0';

    va_start(ap, format);
    if ((msg_type & LOADER_INFO_BIT) != 0) {
        strncat(cmd_line_msg, "INFO", cmd_line_size);
        cmd_line_size -= 4;
    }
    if ((msg_type & LOADER_WARN_BIT) != 0) {
        if (cmd_line_size != sizeof(cmd_line_msg)) {
            strncat(cmd_line_msg, " | ", cmd_line_size);
            cmd_line_size -= 3;
        }
        strncat(cmd_line_msg, "WARNING", cmd_line_size);
        cmd_line_size -= 7;
    }
    if ((msg_type & LOADER_PERF_BIT) != 0) {
        if (cmd_line_size != sizeof(cmd_line_msg)) {
            strncat(cmd_line_msg, " | ", cmd_line_size);
            cmd_line_size -= 3;
        }
        strncat(cmd_line_msg, "PERF", cmd_line_size);
        cmd_line_size -= 4;
    }
    if ((msg_type & LOADER_ERROR_BIT) != 0) {
        if (cmd_line_size != sizeof(cmd_line_msg)) {
            strncat(cmd_line_msg, " | ", cmd_line_size);
            cmd_line_size -= 3;
        }
        strncat(cmd_line_msg, "ERROR", cmd_line_size);
        cmd_line_size -= 5;
    }
    if ((msg_type & LOADER_DEBUG_BIT) != 0) {
        if (cmd_line_size != sizeof(cmd_line_msg)) {
            strncat(cmd_line_msg, " | ", cmd_line_size);
            cmd_line_size -= 3;
        }
        strncat(cmd_line_msg, "DEBUG", cmd_line_size);
        cmd_line_size -= 5;
    }
    if (cmd_line_size != sizeof(cmd_line_msg)) {
        strncat(cmd_line_msg, ": ", cmd_line_size);
        cmd_line_size -= 2;
    }
    strncat(cmd_line_msg, msg, cmd_line_size);

#if defined(WIN32)
    OutputDebugString(cmd_line_msg);
    OutputDebugString("\n");
#endif
    fputs(cmd_line_msg, stderr);
    fputc('\n', stderr);
}

VKAPI_ATTR VkResult VKAPI_CALL vkSetInstanceDispatch(VkInstance instance, void *object) {
    struct loader_instance *inst = loader_get_instance(instance);
    if (!inst) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "vkSetInstanceDispatch: Can not retrieve Instance "
                   "dispatch table.");
        return VK_ERROR_INITIALIZATION_FAILED;
    }
    loader_set_dispatch(object, inst->disp);
    return VK_SUCCESS;
}

VKAPI_ATTR VkResult VKAPI_CALL vkSetDeviceDispatch(VkDevice device, void *object) {
    struct loader_device *dev;
    struct loader_icd_term *icd_term = loader_get_icd_and_device(device, &dev, NULL);

    if (NULL == icd_term) {
        return VK_ERROR_INITIALIZATION_FAILED;
    }
    loader_set_dispatch(object, &dev->loader_dispatch);
    return VK_SUCCESS;
}

#if defined(WIN32)
static char *loader_get_next_path(char *path);

// Find the list of registry files (names within a key) in key "location".
//
// This function looks in the registry (hive = DEFAULT_VK_REGISTRY_HIVE) key as
// given in "location"
// for a list or name/values which are added to a returned list (function return
// value).
// The DWORD values within the key must be 0 or they are skipped.
// Function return is a string with a ';'  separated list of filenames.
// Function return is NULL if no valid name/value pairs  are found in the key,
// or the key is not found.
//
// *reg_data contains a string list of filenames as pointer.
// When done using the returned string list, the caller should free the pointer.
VkResult loaderGetRegistryFiles(const struct loader_instance *inst, char *location, char **reg_data) {
    LONG rtn_value;
    HKEY hive, key;
    DWORD access_flags;
    char name[2048];
    char *loc = location;
    char *next;
    DWORD idx = 0;
    DWORD name_size = sizeof(name);
    DWORD value;
    DWORD total_size = 4096;
    DWORD value_size = sizeof(value);
    VkResult result = VK_SUCCESS;
    bool found = false;

    if (NULL == reg_data) {
        result = VK_ERROR_INITIALIZATION_FAILED;
        goto out;
    }

    while (*loc) {
        next = loader_get_next_path(loc);
        hive = DEFAULT_VK_REGISTRY_HIVE;
        access_flags = KEY_QUERY_VALUE;
        rtn_value = RegOpenKeyEx(hive, loc, 0, access_flags, &key);
        if (ERROR_SUCCESS != rtn_value) {
            // We still couldn't find the key, so give up:
            loc = next;
            continue;
        }

        while ((rtn_value = RegEnumValue(key, idx++, name, &name_size, NULL, NULL, (LPBYTE)&value, &value_size)) == ERROR_SUCCESS) {
            if (value_size == sizeof(value) && value == 0) {
                if (NULL == *reg_data) {
                    *reg_data = loader_instance_heap_alloc(inst, total_size, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
                    if (NULL == *reg_data) {
                        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                                   "loaderGetRegistryFiles: Failed to allocate "
                                   "space for registry data for key %s",
                                   name);
                        result = VK_ERROR_OUT_OF_HOST_MEMORY;
                        goto out;
                    }
                    *reg_data[0] = '\0';
                } else if (strlen(*reg_data) + name_size + 1 > total_size) {
                    *reg_data = loader_instance_heap_realloc(inst, *reg_data, total_size, total_size * 2,
                                                             VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
                    if (NULL == *reg_data) {
                        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                                   "loaderGetRegistryFiles: Failed to reallocate "
                                   "space for registry value of size %d for key %s",
                                   total_size * 2, name);
                        result = VK_ERROR_OUT_OF_HOST_MEMORY;
                        goto out;
                    }
                    total_size *= 2;
                }
                if (strlen(*reg_data) == 0) {
                    (void)snprintf(*reg_data, name_size + 1, "%s", name);
                } else {
                    (void)snprintf(*reg_data + strlen(*reg_data), name_size + 2, "%c%s", PATH_SEPARATOR, name);
                }
                found = true;
            }
            name_size = 2048;
        }
        loc = next;
    }

    if (!found) {
        result = VK_ERROR_INITIALIZATION_FAILED;
    }

out:

    return result;
}

#endif  // WIN32

/**
 * Combine path elements, separating each element with the platform-specific
 * directory separator, and save the combined string to a destination buffer,
 * not exceeding the given length. Path elements are given as variadic args,
 * with a NULL element terminating the list.
 *
 * \returns the total length of the combined string, not including an ASCII
 * NUL termination character. This length may exceed the available storage:
 * in this case, the written string will be truncated to avoid a buffer
 * overrun, and the return value will greater than or equal to the storage
 * size. A NULL argument may be provided as the destination buffer in order
 * to determine the required string length without actually writing a string.
 */

static size_t loader_platform_combine_path(char *dest, size_t len, ...) {
    size_t required_len = 0;
    va_list ap;
    const char *component;

    va_start(ap, len);

    while ((component = va_arg(ap, const char *))) {
        if (required_len > 0) {
            // This path element is not the first non-empty element; prepend
            // a directory separator if space allows
            if (dest && required_len + 1 < len) {
                (void)snprintf(dest + required_len, len - required_len, "%c", DIRECTORY_SYMBOL);
            }
            required_len++;
        }

        if (dest && required_len < len) {
            strncpy(dest + required_len, component, len - required_len);
        }
        required_len += strlen(component);
    }

    va_end(ap);

    // strncpy(3) won't add a NUL terminating byte in the event of truncation.
    if (dest && required_len >= len) {
        dest[len - 1] = '\0';
    }

    return required_len;
}

/**
 * Given string of three part form "maj.min.pat" convert to a vulkan version
 * number.
 */
static uint32_t loader_make_version(char *vers_str) {
    uint32_t vers = 0, major = 0, minor = 0, patch = 0;
    char *vers_tok;

    if (!vers_str) {
        return vers;
    }

    vers_tok = strtok(vers_str, ".\"\n\r");
    if (NULL != vers_tok) {
        major = (uint16_t)atoi(vers_tok);
        vers_tok = strtok(NULL, ".\"\n\r");
        if (NULL != vers_tok) {
            minor = (uint16_t)atoi(vers_tok);
            vers_tok = strtok(NULL, ".\"\n\r");
            if (NULL != vers_tok) {
                patch = (uint16_t)atoi(vers_tok);
            }
        }
    }

    return VK_MAKE_VERSION(major, minor, patch);
}

bool compare_vk_extension_properties(const VkExtensionProperties *op1, const VkExtensionProperties *op2) {
    return strcmp(op1->extensionName, op2->extensionName) == 0 ? true : false;
}

/**
 * Search the given ext_array for an extension
 * matching the given vk_ext_prop
 */
bool has_vk_extension_property_array(const VkExtensionProperties *vk_ext_prop, const uint32_t count,
                                     const VkExtensionProperties *ext_array) {
    for (uint32_t i = 0; i < count; i++) {
        if (compare_vk_extension_properties(vk_ext_prop, &ext_array[i])) return true;
    }
    return false;
}

/**
 * Search the given ext_list for an extension
 * matching the given vk_ext_prop
 */
bool has_vk_extension_property(const VkExtensionProperties *vk_ext_prop, const struct loader_extension_list *ext_list) {
    for (uint32_t i = 0; i < ext_list->count; i++) {
        if (compare_vk_extension_properties(&ext_list->list[i], vk_ext_prop)) return true;
    }
    return false;
}

/**
 * Search the given ext_list for a device extension matching the given ext_prop
 */
bool has_vk_dev_ext_property(const VkExtensionProperties *ext_prop, const struct loader_device_extension_list *ext_list) {
    for (uint32_t i = 0; i < ext_list->count; i++) {
        if (compare_vk_extension_properties(&ext_list->list[i].props, ext_prop)) return true;
    }
    return false;
}

/*
 * Search the given layer list for a layer matching the given layer name
 */
static struct loader_layer_properties *loader_get_layer_property(const char *name, const struct loader_layer_list *layer_list) {
    for (uint32_t i = 0; i < layer_list->count; i++) {
        const VkLayerProperties *item = &layer_list->list[i].info;
        if (strcmp(name, item->layerName) == 0) return &layer_list->list[i];
    }
    return NULL;
}

/**
 * Get the next unused layer property in the list. Init the property to zero.
 */
static struct loader_layer_properties *loader_get_next_layer_property(const struct loader_instance *inst,
                                                                      struct loader_layer_list *layer_list) {
    if (layer_list->capacity == 0) {
        layer_list->list =
            loader_instance_heap_alloc(inst, sizeof(struct loader_layer_properties) * 64, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (layer_list->list == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_get_next_layer_property: Out of memory can "
                       "not add any layer properties to list");
            return NULL;
        }
        memset(layer_list->list, 0, sizeof(struct loader_layer_properties) * 64);
        layer_list->capacity = sizeof(struct loader_layer_properties) * 64;
    }

    // ensure enough room to add an entry
    if ((layer_list->count + 1) * sizeof(struct loader_layer_properties) > layer_list->capacity) {
        layer_list->list = loader_instance_heap_realloc(inst, layer_list->list, layer_list->capacity, layer_list->capacity * 2,
                                                        VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (layer_list->list == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_get_next_layer_property: realloc failed for "
                       "layer list");
            return NULL;
        }
        layer_list->capacity *= 2;
    }

    layer_list->count++;
    return &(layer_list->list[layer_list->count - 1]);
}

/**
 * Remove all layer properties entrys from the list
 */
void loader_delete_layer_properties(const struct loader_instance *inst, struct loader_layer_list *layer_list) {
    uint32_t i, j;
    struct loader_device_extension_list *dev_ext_list;
    if (!layer_list) return;

    for (i = 0; i < layer_list->count; i++) {
        loader_destroy_generic_list(inst, (struct loader_generic_list *)&layer_list->list[i].instance_extension_list);
        dev_ext_list = &layer_list->list[i].device_extension_list;
        if (dev_ext_list->capacity > 0 && NULL != dev_ext_list->list && dev_ext_list->list->entrypoint_count > 0) {
            for (j = 0; j < dev_ext_list->list->entrypoint_count; j++) {
                loader_instance_heap_free(inst, dev_ext_list->list->entrypoints[j]);
            }
            loader_instance_heap_free(inst, dev_ext_list->list->entrypoints);
        }
        loader_destroy_generic_list(inst, (struct loader_generic_list *)dev_ext_list);
    }
    layer_list->count = 0;

    if (layer_list->capacity > 0) {
        layer_list->capacity = 0;
        loader_instance_heap_free(inst, layer_list->list);
    }
}

static VkResult loader_add_instance_extensions(const struct loader_instance *inst,
                                               const PFN_vkEnumerateInstanceExtensionProperties fp_get_props, const char *lib_name,
                                               struct loader_extension_list *ext_list) {
    uint32_t i, count = 0;
    VkExtensionProperties *ext_props;
    VkResult res = VK_SUCCESS;

    if (!fp_get_props) {
        /* No EnumerateInstanceExtensionProperties defined */
        goto out;
    }

    res = fp_get_props(NULL, &count, NULL);
    if (res != VK_SUCCESS) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_add_instance_extensions: Error getting Instance "
                   "extension count from %s",
                   lib_name);
        goto out;
    }

    if (count == 0) {
        /* No ExtensionProperties to report */
        goto out;
    }

    ext_props = loader_stack_alloc(count * sizeof(VkExtensionProperties));
    if (NULL == ext_props) {
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }

    res = fp_get_props(NULL, &count, ext_props);
    if (res != VK_SUCCESS) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_add_instance_extensions: Error getting Instance "
                   "extensions from %s",
                   lib_name);
        goto out;
    }

    for (i = 0; i < count; i++) {
        char spec_version[64];

        bool ext_unsupported = wsi_unsupported_instance_extension(&ext_props[i]);
        if (!ext_unsupported) {
            (void)snprintf(spec_version, sizeof(spec_version), "%d.%d.%d", VK_MAJOR(ext_props[i].specVersion),
                           VK_MINOR(ext_props[i].specVersion), VK_PATCH(ext_props[i].specVersion));
            loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Instance Extension: %s (%s) version %s", ext_props[i].extensionName,
                       lib_name, spec_version);

            res = loader_add_to_ext_list(inst, ext_list, 1, &ext_props[i]);
            if (res != VK_SUCCESS) {
                loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                           "loader_add_instance_extensions: Failed to add %s "
                           "to Instance extension list",
                           lib_name);
                goto out;
            }
        }
    }

out:
    return res;
}

/*
 * Initialize ext_list with the physical device extensions.
 * The extension properties are passed as inputs in count and ext_props.
 */
static VkResult loader_init_device_extensions(const struct loader_instance *inst, struct loader_physical_device_term *phys_dev_term,
                                              uint32_t count, VkExtensionProperties *ext_props,
                                              struct loader_extension_list *ext_list) {
    VkResult res;
    uint32_t i;

    res = loader_init_generic_list(inst, (struct loader_generic_list *)ext_list, sizeof(VkExtensionProperties));
    if (VK_SUCCESS != res) {
        return res;
    }

    for (i = 0; i < count; i++) {
        char spec_version[64];

        (void)snprintf(spec_version, sizeof(spec_version), "%d.%d.%d", VK_MAJOR(ext_props[i].specVersion),
                       VK_MINOR(ext_props[i].specVersion), VK_PATCH(ext_props[i].specVersion));
        loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Device Extension: %s (%s) version %s", ext_props[i].extensionName,
                   phys_dev_term->this_icd_term->scanned_icd->lib_name, spec_version);
        res = loader_add_to_ext_list(inst, ext_list, 1, &ext_props[i]);
        if (res != VK_SUCCESS) return res;
    }

    return VK_SUCCESS;
}

VkResult loader_add_device_extensions(const struct loader_instance *inst,
                                      PFN_vkEnumerateDeviceExtensionProperties fpEnumerateDeviceExtensionProperties,
                                      VkPhysicalDevice physical_device, const char *lib_name,
                                      struct loader_extension_list *ext_list) {
    uint32_t i, count;
    VkResult res;
    VkExtensionProperties *ext_props;

    res = fpEnumerateDeviceExtensionProperties(physical_device, NULL, &count, NULL);
    if (res == VK_SUCCESS && count > 0) {
        ext_props = loader_stack_alloc(count * sizeof(VkExtensionProperties));
        if (!ext_props) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_add_device_extensions: Failed to allocate space"
                       " for device extension properties.");
            return VK_ERROR_OUT_OF_HOST_MEMORY;
        }
        res = fpEnumerateDeviceExtensionProperties(physical_device, NULL, &count, ext_props);
        if (res != VK_SUCCESS) {
            return res;
        }
        for (i = 0; i < count; i++) {
            char spec_version[64];

            (void)snprintf(spec_version, sizeof(spec_version), "%d.%d.%d", VK_MAJOR(ext_props[i].specVersion),
                           VK_MINOR(ext_props[i].specVersion), VK_PATCH(ext_props[i].specVersion));
            loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Device Extension: %s (%s) version %s", ext_props[i].extensionName,
                       lib_name, spec_version);
            res = loader_add_to_ext_list(inst, ext_list, 1, &ext_props[i]);
            if (res != VK_SUCCESS) {
                return res;
            }
        }
    } else {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_add_device_extensions: Error getting physical "
                   "device extension info count from library %s",
                   lib_name);
        return res;
    }

    return VK_SUCCESS;
}

VkResult loader_init_generic_list(const struct loader_instance *inst, struct loader_generic_list *list_info, size_t element_size) {
    size_t capacity = 32 * element_size;
    list_info->count = 0;
    list_info->capacity = 0;
    list_info->list = loader_instance_heap_alloc(inst, capacity, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (list_info->list == NULL) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_init_generic_list: Failed to allocate space "
                   "for generic list");
        return VK_ERROR_OUT_OF_HOST_MEMORY;
    }
    memset(list_info->list, 0, capacity);
    list_info->capacity = capacity;
    return VK_SUCCESS;
}

void loader_destroy_generic_list(const struct loader_instance *inst, struct loader_generic_list *list) {
    loader_instance_heap_free(inst, list->list);
    list->count = 0;
    list->capacity = 0;
}

/*
 * Append non-duplicate extension properties defined in props
 * to the given ext_list.
 * Return
 *  Vk_SUCCESS on success
 */
VkResult loader_add_to_ext_list(const struct loader_instance *inst, struct loader_extension_list *ext_list,
                                uint32_t prop_list_count, const VkExtensionProperties *props) {
    uint32_t i;
    const VkExtensionProperties *cur_ext;

    if (ext_list->list == NULL || ext_list->capacity == 0) {
        VkResult res = loader_init_generic_list(inst, (struct loader_generic_list *)ext_list, sizeof(VkExtensionProperties));
        if (VK_SUCCESS != res) {
            return res;
        }
    }

    for (i = 0; i < prop_list_count; i++) {
        cur_ext = &props[i];

        // look for duplicates
        if (has_vk_extension_property(cur_ext, ext_list)) {
            continue;
        }

        // add to list at end
        // check for enough capacity
        if (ext_list->count * sizeof(VkExtensionProperties) >= ext_list->capacity) {
            ext_list->list = loader_instance_heap_realloc(inst, ext_list->list, ext_list->capacity, ext_list->capacity * 2,
                                                          VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);

            if (ext_list->list == NULL) {
                loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                           "loader_add_to_ext_list: Failed to reallocate "
                           "space for extension list");
                return VK_ERROR_OUT_OF_HOST_MEMORY;
            }

            // double capacity
            ext_list->capacity *= 2;
        }

        memcpy(&ext_list->list[ext_list->count], cur_ext, sizeof(VkExtensionProperties));
        ext_list->count++;
    }
    return VK_SUCCESS;
}

/*
 * Append one extension property defined in props with entrypoints
 * defined in entrys to the given ext_list. Do not append if a duplicate
 * Return
 *  Vk_SUCCESS on success
 */
VkResult loader_add_to_dev_ext_list(const struct loader_instance *inst, struct loader_device_extension_list *ext_list,
                                    const VkExtensionProperties *props, uint32_t entry_count, char **entrys) {
    uint32_t idx;
    if (ext_list->list == NULL || ext_list->capacity == 0) {
        VkResult res = loader_init_generic_list(inst, (struct loader_generic_list *)ext_list, sizeof(struct loader_dev_ext_props));
        if (VK_SUCCESS != res) {
            return res;
        }
    }

    // look for duplicates
    if (has_vk_dev_ext_property(props, ext_list)) {
        return VK_SUCCESS;
    }

    idx = ext_list->count;
    // add to list at end
    // check for enough capacity
    if (idx * sizeof(struct loader_dev_ext_props) >= ext_list->capacity) {
        ext_list->list = loader_instance_heap_realloc(inst, ext_list->list, ext_list->capacity, ext_list->capacity * 2,
                                                      VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);

        if (ext_list->list == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_add_to_dev_ext_list: Failed to reallocate "
                       "space for device extension list");
            return VK_ERROR_OUT_OF_HOST_MEMORY;
        }

        // double capacity
        ext_list->capacity *= 2;
    }

    memcpy(&ext_list->list[idx].props, props, sizeof(struct loader_dev_ext_props));
    ext_list->list[idx].entrypoint_count = entry_count;
    ext_list->list[idx].entrypoints =
        loader_instance_heap_alloc(inst, sizeof(char *) * entry_count, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (ext_list->list[idx].entrypoints == NULL) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_add_to_dev_ext_list: Failed to allocate space "
                   "for device extension entrypoint list in list %d",
                   idx);
        ext_list->list[idx].entrypoint_count = 0;
        return VK_ERROR_OUT_OF_HOST_MEMORY;
    }
    for (uint32_t i = 0; i < entry_count; i++) {
        ext_list->list[idx].entrypoints[i] =
            loader_instance_heap_alloc(inst, strlen(entrys[i]) + 1, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (ext_list->list[idx].entrypoints[i] == NULL) {
            for (uint32_t j = 0; j < i; j++) {
                loader_instance_heap_free(inst, ext_list->list[idx].entrypoints[j]);
            }
            loader_instance_heap_free(inst, ext_list->list[idx].entrypoints);
            ext_list->list[idx].entrypoint_count = 0;
            ext_list->list[idx].entrypoints = NULL;
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_add_to_dev_ext_list: Failed to allocate space "
                       "for device extension entrypoint %d name",
                       i);
            return VK_ERROR_OUT_OF_HOST_MEMORY;
        }
        strcpy(ext_list->list[idx].entrypoints[i], entrys[i]);
    }
    ext_list->count++;

    return VK_SUCCESS;
}

/**
 * Search the given search_list for any layers in the props list.
 * Add these to the output layer_list.  Don't add duplicates to the output
 * layer_list.
 */
static VkResult loader_add_layer_names_to_list(const struct loader_instance *inst, struct loader_layer_list *output_list,
                                               uint32_t name_count, const char *const *names,
                                               const struct loader_layer_list *search_list) {
    struct loader_layer_properties *layer_prop;
    VkResult err = VK_SUCCESS;

    for (uint32_t i = 0; i < name_count; i++) {
        const char *search_target = names[i];
        layer_prop = loader_get_layer_property(search_target, search_list);
        if (!layer_prop) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_add_layer_names_to_list: Unable to find layer"
                       " %s",
                       search_target);
            err = VK_ERROR_LAYER_NOT_PRESENT;
            continue;
        }

        err = loader_add_to_layer_list(inst, output_list, 1, layer_prop);
    }

    return err;
}

/*
 * Manage lists of VkLayerProperties
 */
static bool loader_init_layer_list(const struct loader_instance *inst, struct loader_layer_list *list) {
    list->capacity = 32 * sizeof(struct loader_layer_properties);
    list->list = loader_instance_heap_alloc(inst, list->capacity, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (list->list == NULL) {
        return false;
    }
    memset(list->list, 0, list->capacity);
    list->count = 0;
    return true;
}

void loader_destroy_layer_list(const struct loader_instance *inst, struct loader_device *device,
                               struct loader_layer_list *layer_list) {
    if (device) {
        loader_device_heap_free(device, layer_list->list);
    } else {
        loader_instance_heap_free(inst, layer_list->list);
    }
    layer_list->count = 0;
    layer_list->capacity = 0;
}

/*
 * Search the given layer list for a list
 * matching the given VkLayerProperties
 */
bool has_vk_layer_property(const VkLayerProperties *vk_layer_prop, const struct loader_layer_list *list) {
    for (uint32_t i = 0; i < list->count; i++) {
        if (strcmp(vk_layer_prop->layerName, list->list[i].info.layerName) == 0) return true;
    }
    return false;
}

/*
 * Search the given layer list for a layer
 * matching the given name
 */
bool has_layer_name(const char *name, const struct loader_layer_list *list) {
    for (uint32_t i = 0; i < list->count; i++) {
        if (strcmp(name, list->list[i].info.layerName) == 0) return true;
    }
    return false;
}

/*
 * Append non-duplicate layer properties defined in prop_list
 * to the given layer_info list
 */
VkResult loader_add_to_layer_list(const struct loader_instance *inst, struct loader_layer_list *list, uint32_t prop_list_count,
                                  const struct loader_layer_properties *props) {
    uint32_t i;
    struct loader_layer_properties *layer;

    if (list->list == NULL || list->capacity == 0) {
        loader_init_layer_list(inst, list);
    }

    if (list->list == NULL) return VK_SUCCESS;

    for (i = 0; i < prop_list_count; i++) {
        layer = (struct loader_layer_properties *)&props[i];

        // look for duplicates
        if (has_vk_layer_property(&layer->info, list)) {
            continue;
        }

        // add to list at end
        // check for enough capacity
        if (list->count * sizeof(struct loader_layer_properties) >= list->capacity) {
            list->list = loader_instance_heap_realloc(inst, list->list, list->capacity, list->capacity * 2,
                                                      VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
            if (NULL == list->list) {
                loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                           "loader_add_to_layer_list: Realloc failed for "
                           "when attempting to add new layer");
                return VK_ERROR_OUT_OF_HOST_MEMORY;
            }
            // double capacity
            list->capacity *= 2;
        }

        memcpy(&list->list[list->count], layer, sizeof(struct loader_layer_properties));
        list->count++;
    }

    return VK_SUCCESS;
}

/**
 * Search the search_list for any layer with a name
 * that matches the given name and a type that matches the given type
 * Add all matching layers to the found_list
 * Do not add if found loader_layer_properties is already
 * on the found_list.
 */
void loader_find_layer_name_add_list(const struct loader_instance *inst, const char *name, const enum layer_type type,
                                     const struct loader_layer_list *search_list, struct loader_layer_list *found_list) {
    bool found = false;
    for (uint32_t i = 0; i < search_list->count; i++) {
        struct loader_layer_properties *layer_prop = &search_list->list[i];
        if (0 == strcmp(layer_prop->info.layerName, name) && (layer_prop->type & type)) {
            /* Found a layer with the same name, add to found_list */
            if (VK_SUCCESS == loader_add_to_layer_list(inst, found_list, 1, layer_prop)) {
                found = true;
            }
        }
    }
    if (!found) {
        loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                   "loader_find_layer_name_add_list: Failed to find layer name "
                   "%s to activate",
                   name);
    }
}

static VkExtensionProperties *get_extension_property(const char *name, const struct loader_extension_list *list) {
    for (uint32_t i = 0; i < list->count; i++) {
        if (strcmp(name, list->list[i].extensionName) == 0) return &list->list[i];
    }
    return NULL;
}

static VkExtensionProperties *get_dev_extension_property(const char *name, const struct loader_device_extension_list *list) {
    for (uint32_t i = 0; i < list->count; i++) {
        if (strcmp(name, list->list[i].props.extensionName) == 0) return &list->list[i].props;
    }
    return NULL;
}

/*
 * For Instance extensions implemented within the loader (i.e. DEBUG_REPORT
 * the extension must provide two entry points for the loader to use:
 * - "trampoline" entry point - this is the address returned by GetProcAddr
 * and will always do what's necessary to support a global call.
 * - "terminator" function - this function will be put at the end of the
 * instance chain and will contain the necessary logic to call / process
 * the extension for the appropriate ICDs that are available.
 * There is no generic mechanism for including these functions, the references
 * must be placed into the appropriate loader entry points.
 * GetInstanceProcAddr: call extension GetInstanceProcAddr to check for
 * GetProcAddr requests
 * loader_coalesce_extensions(void) - add extension records to the list of
 * global
 * extension available to the app.
 * instance_disp - add function pointer for terminator function to this array.
 * The extension itself should be in a separate file that will be
 * linked directly with the loader.
 */

VkResult loader_get_icd_loader_instance_extensions(const struct loader_instance *inst, struct loader_icd_tramp_list *icd_tramp_list,
                                                   struct loader_extension_list *inst_exts) {
    struct loader_extension_list icd_exts;
    VkResult res = VK_SUCCESS;
    char *env_value;
    bool filter_extensions = true;

    loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Build ICD instance extension list");

    // Check if a user wants to disable the instance extension filtering behavior
    env_value = loader_getenv("VK_LOADER_DISABLE_INST_EXT_FILTER", inst);
    if (NULL != env_value && atoi(env_value) != 0) {
        filter_extensions = false;
    }
    loader_free_getenv(env_value, inst);

    // traverse scanned icd list adding non-duplicate extensions to the list
    for (uint32_t i = 0; i < icd_tramp_list->count; i++) {
        res = loader_init_generic_list(inst, (struct loader_generic_list *)&icd_exts, sizeof(VkExtensionProperties));
        if (VK_SUCCESS != res) {
            goto out;
        }
        res = loader_add_instance_extensions(inst, icd_tramp_list->scanned_list[i].EnumerateInstanceExtensionProperties,
                                             icd_tramp_list->scanned_list[i].lib_name, &icd_exts);
        if (VK_SUCCESS == res) {
            if (filter_extensions) {
                // Remove any extensions not recognized by the loader
                for (int32_t j = 0; j < (int32_t)icd_exts.count; j++) {
                    // See if the extension is in the list of supported extensions
                    bool found = false;
                    for (uint32_t k = 0; LOADER_INSTANCE_EXTENSIONS[k] != NULL; k++) {
                        if (strcmp(icd_exts.list[j].extensionName, LOADER_INSTANCE_EXTENSIONS[k]) == 0) {
                            found = true;
                            break;
                        }
                    }

                    // If it isn't in the list, remove it
                    if (!found) {
                        for (uint32_t k = j + 1; k < icd_exts.count; k++) {
                            icd_exts.list[k - 1] = icd_exts.list[k];
                        }
                        --icd_exts.count;
                        --j;
                    }
                }
            }

            res = loader_add_to_ext_list(inst, inst_exts, icd_exts.count, icd_exts.list);
        }
        loader_destroy_generic_list(inst, (struct loader_generic_list *)&icd_exts);
        if (VK_SUCCESS != res) {
            goto out;
        }
    };

    // Traverse loader's extensions, adding non-duplicate extensions to the list
    debug_report_add_instance_extensions(inst, inst_exts);

out:
    return res;
}

struct loader_icd_term *loader_get_icd_and_device(const VkDevice device, struct loader_device **found_dev, uint32_t *icd_index) {
    *found_dev = NULL;
    uint32_t index = 0;
    for (struct loader_instance *inst = loader.instances; inst; inst = inst->next) {
        for (struct loader_icd_term *icd_term = inst->icd_terms; icd_term; icd_term = icd_term->next) {
            for (struct loader_device *dev = icd_term->logical_device_list; dev; dev = dev->next)
                // Value comparison of device prevents object wrapping by layers
                if (loader_get_dispatch(dev->icd_device) == loader_get_dispatch(device) ||
                    loader_get_dispatch(dev->chain_device) == loader_get_dispatch(device)) {
                    *found_dev = dev;
                    if (NULL != icd_index) {
                        *icd_index = index;
                    }
                    return icd_term;
                }
            index++;
        }
    }
    return NULL;
}

void loader_destroy_logical_device(const struct loader_instance *inst, struct loader_device *dev,
                                   const VkAllocationCallbacks *pAllocator) {
    if (pAllocator) {
        dev->alloc_callbacks = *pAllocator;
    }
    if (NULL != dev->activated_layer_list.list) {
        loader_deactivate_layers(inst, dev, &dev->activated_layer_list);
    }
    loader_device_heap_free(dev, dev);
}

struct loader_device *loader_create_logical_device(const struct loader_instance *inst, const VkAllocationCallbacks *pAllocator) {
    struct loader_device *new_dev;
#if (DEBUG_DISABLE_APP_ALLOCATORS == 1)
    {
#else
    if (pAllocator) {
        new_dev = (struct loader_device *)pAllocator->pfnAllocation(pAllocator->pUserData, sizeof(struct loader_device),
                                                                    sizeof(int *), VK_SYSTEM_ALLOCATION_SCOPE_DEVICE);
    } else {
#endif
        new_dev = (struct loader_device *)malloc(sizeof(struct loader_device));
    }

    if (!new_dev) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_create_logical_device: Failed to alloc struct "
                   "loader_device");
        return NULL;
    }

    memset(new_dev, 0, sizeof(struct loader_device));
    if (pAllocator) {
        new_dev->alloc_callbacks = *pAllocator;
    }

    return new_dev;
}

void loader_add_logical_device(const struct loader_instance *inst, struct loader_icd_term *icd_term, struct loader_device *dev) {
    dev->next = icd_term->logical_device_list;
    icd_term->logical_device_list = dev;
}

void loader_remove_logical_device(const struct loader_instance *inst, struct loader_icd_term *icd_term,
                                  struct loader_device *found_dev, const VkAllocationCallbacks *pAllocator) {
    struct loader_device *dev, *prev_dev;

    if (!icd_term || !found_dev) return;

    prev_dev = NULL;
    dev = icd_term->logical_device_list;
    while (dev && dev != found_dev) {
        prev_dev = dev;
        dev = dev->next;
    }

    if (prev_dev)
        prev_dev->next = found_dev->next;
    else
        icd_term->logical_device_list = found_dev->next;
    loader_destroy_logical_device(inst, found_dev, pAllocator);
}

static void loader_icd_destroy(struct loader_instance *ptr_inst, struct loader_icd_term *icd_term,
                               const VkAllocationCallbacks *pAllocator) {
    ptr_inst->total_icd_count--;
    for (struct loader_device *dev = icd_term->logical_device_list; dev;) {
        struct loader_device *next_dev = dev->next;
        loader_destroy_logical_device(ptr_inst, dev, pAllocator);
        dev = next_dev;
    }

    loader_instance_heap_free(ptr_inst, icd_term);
}

static struct loader_icd_term *loader_icd_create(const struct loader_instance *inst) {
    struct loader_icd_term *icd_term;

    icd_term = loader_instance_heap_alloc(inst, sizeof(struct loader_icd_term), VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (!icd_term) {
        return NULL;
    }

    memset(icd_term, 0, sizeof(struct loader_icd_term));

    return icd_term;
}

static struct loader_icd_term *loader_icd_add(struct loader_instance *ptr_inst, const struct loader_scanned_icd *scanned_icd) {
    struct loader_icd_term *icd_term;

    icd_term = loader_icd_create(ptr_inst);
    if (!icd_term) {
        return NULL;
    }

    icd_term->scanned_icd = scanned_icd;
    icd_term->this_instance = ptr_inst;

    /* prepend to the list */
    icd_term->next = ptr_inst->icd_terms;
    ptr_inst->icd_terms = icd_term;
    ptr_inst->total_icd_count++;

    return icd_term;
}

/**
 * Determine the ICD interface version to use.
 * @param icd
 * @param pVersion Output parameter indicating which version to use or 0 if
 * the negotiation API is not supported by the ICD
 * @return  bool indicating true if the selected interface version is supported
 *          by the loader, false indicates the version is not supported
 */
bool loader_get_icd_interface_version(PFN_vkNegotiateLoaderICDInterfaceVersion fp_negotiate_icd_version, uint32_t *pVersion) {
    if (fp_negotiate_icd_version == NULL) {
        // ICD does not support the negotiation API, it supports version 0 or 1
        // calling code must determine if it is version 0 or 1
        *pVersion = 0;
    } else {
        // ICD supports the negotiation API, so call it with the loader's
        // latest version supported
        *pVersion = CURRENT_LOADER_ICD_INTERFACE_VERSION;
        VkResult result = fp_negotiate_icd_version(pVersion);

        if (result == VK_ERROR_INCOMPATIBLE_DRIVER) {
            // ICD no longer supports the loader's latest interface version so
            // fail loading the ICD
            return false;
        }
    }

#if MIN_SUPPORTED_LOADER_ICD_INTERFACE_VERSION > 0
    if (*pVersion < MIN_SUPPORTED_LOADER_ICD_INTERFACE_VERSION) {
        // Loader no longer supports the ICD's latest interface version so fail
        // loading the ICD
        return false;
    }
#endif
    return true;
}

void loader_scanned_icd_clear(const struct loader_instance *inst, struct loader_icd_tramp_list *icd_tramp_list) {
    if (icd_tramp_list->capacity == 0) return;
    for (uint32_t i = 0; i < icd_tramp_list->count; i++) {
        loader_platform_close_library(icd_tramp_list->scanned_list[i].handle);
        loader_instance_heap_free(inst, icd_tramp_list->scanned_list[i].lib_name);
    }
    loader_instance_heap_free(inst, icd_tramp_list->scanned_list);
    icd_tramp_list->capacity = 0;
    icd_tramp_list->count = 0;
    icd_tramp_list->scanned_list = NULL;
}

static VkResult loader_scanned_icd_init(const struct loader_instance *inst, struct loader_icd_tramp_list *icd_tramp_list) {
    VkResult err = VK_SUCCESS;
    loader_scanned_icd_clear(inst, icd_tramp_list);
    icd_tramp_list->capacity = 8 * sizeof(struct loader_scanned_icd);
    icd_tramp_list->scanned_list = loader_instance_heap_alloc(inst, icd_tramp_list->capacity, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (NULL == icd_tramp_list->scanned_list) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_scanned_icd_init: Realloc failed for layer list when "
                   "attempting to add new layer");
        err = VK_ERROR_OUT_OF_HOST_MEMORY;
    }
    return err;
}

static VkResult loader_scanned_icd_add(const struct loader_instance *inst, struct loader_icd_tramp_list *icd_tramp_list,
                                       const char *filename, uint32_t api_version) {
    loader_platform_dl_handle handle;
    PFN_vkCreateInstance fp_create_inst;
    PFN_vkEnumerateInstanceExtensionProperties fp_get_inst_ext_props;
    PFN_vkGetInstanceProcAddr fp_get_proc_addr;
    PFN_GetPhysicalDeviceProcAddr fp_get_phys_dev_proc_addr = NULL;
    PFN_vkNegotiateLoaderICDInterfaceVersion fp_negotiate_icd_version;
    struct loader_scanned_icd *new_scanned_icd;
    uint32_t interface_vers;
    VkResult res = VK_SUCCESS;

    /* TODO implement smarter opening/closing of libraries. For now this
     * function leaves libraries open and the scanned_icd_clear closes them */
    handle = loader_platform_open_library(filename);
    if (NULL == handle) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0, loader_platform_open_library_error(filename));
        goto out;
    }

    // Get and settle on an ICD interface version
    fp_negotiate_icd_version = loader_platform_get_proc_address(handle, "vk_icdNegotiateLoaderICDInterfaceVersion");

    if (!loader_get_icd_interface_version(fp_negotiate_icd_version, &interface_vers)) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_scanned_icd_add: ICD %s doesn't support interface"
                   " version compatible with loader, skip this ICD.",
                   filename);
        goto out;
    }

    fp_get_proc_addr = loader_platform_get_proc_address(handle, "vk_icdGetInstanceProcAddr");
    if (NULL == fp_get_proc_addr) {
        assert(interface_vers == 0);
        // Use deprecated interface from version 0
        fp_get_proc_addr = loader_platform_get_proc_address(handle, "vkGetInstanceProcAddr");
        if (NULL == fp_get_proc_addr) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_scanned_icd_add: Attempt to retreive either "
                       "\'vkGetInstanceProcAddr\' or "
                       "\'vk_icdGetInstanceProcAddr\' from ICD %s failed.",
                       filename);
            goto out;
        } else {
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "loader_scanned_icd_add: Using deprecated ICD "
                       "interface of \'vkGetInstanceProcAddr\' instead of "
                       "\'vk_icdGetInstanceProcAddr\' for ICD %s",
                       filename);
        }
        fp_create_inst = loader_platform_get_proc_address(handle, "vkCreateInstance");
        if (NULL == fp_create_inst) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_scanned_icd_add:  Failed querying "
                       "\'vkCreateInstance\' via dlsym/loadlibrary for "
                       "ICD %s",
                       filename);
            goto out;
        }
        fp_get_inst_ext_props = loader_platform_get_proc_address(handle, "vkEnumerateInstanceExtensionProperties");
        if (NULL == fp_get_inst_ext_props) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_scanned_icd_add: Could not get \'vkEnumerate"
                       "InstanceExtensionProperties\' via dlsym/loadlibrary "
                       "for ICD %s",
                       filename);
            goto out;
        }
    } else {
        // Use newer interface version 1 or later
        if (interface_vers == 0) {
            interface_vers = 1;
        }

        fp_create_inst = (PFN_vkCreateInstance)fp_get_proc_addr(NULL, "vkCreateInstance");
        if (NULL == fp_create_inst) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_scanned_icd_add: Could not get "
                       "\'vkCreateInstance\' via \'vk_icdGetInstanceProcAddr\'"
                       " for ICD %s",
                       filename);
            goto out;
        }
        fp_get_inst_ext_props =
            (PFN_vkEnumerateInstanceExtensionProperties)fp_get_proc_addr(NULL, "vkEnumerateInstanceExtensionProperties");
        if (NULL == fp_get_inst_ext_props) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_scanned_icd_add: Could not get \'vkEnumerate"
                       "InstanceExtensionProperties\' via "
                       "\'vk_icdGetInstanceProcAddr\' for ICD %s",
                       filename);
            goto out;
        }
        fp_get_phys_dev_proc_addr = loader_platform_get_proc_address(handle, "vk_icdGetPhysicalDeviceProcAddr");
    }

    // check for enough capacity
    if ((icd_tramp_list->count * sizeof(struct loader_scanned_icd)) >= icd_tramp_list->capacity) {
        icd_tramp_list->scanned_list =
            loader_instance_heap_realloc(inst, icd_tramp_list->scanned_list, icd_tramp_list->capacity, icd_tramp_list->capacity * 2,
                                         VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (NULL == icd_tramp_list->scanned_list) {
            res = VK_ERROR_OUT_OF_HOST_MEMORY;
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_scanned_icd_add: Realloc failed on icd library"
                       " list for ICD %s",
                       filename);
            goto out;
        }
        // double capacity
        icd_tramp_list->capacity *= 2;
    }

    new_scanned_icd = &(icd_tramp_list->scanned_list[icd_tramp_list->count]);
    new_scanned_icd->handle = handle;
    new_scanned_icd->api_version = api_version;
    new_scanned_icd->GetInstanceProcAddr = fp_get_proc_addr;
    new_scanned_icd->GetPhysicalDeviceProcAddr = fp_get_phys_dev_proc_addr;
    new_scanned_icd->EnumerateInstanceExtensionProperties = fp_get_inst_ext_props;
    new_scanned_icd->CreateInstance = fp_create_inst;
    new_scanned_icd->interface_version = interface_vers;

    new_scanned_icd->lib_name = (char *)loader_instance_heap_alloc(inst, strlen(filename) + 1, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (NULL == new_scanned_icd->lib_name) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0, "loader_scanned_icd_add: Out of memory can't add ICD %s", filename);
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }
    strcpy(new_scanned_icd->lib_name, filename);
    icd_tramp_list->count++;

out:

    return res;
}

static bool loader_icd_init_entrys(struct loader_icd_term *icd_term, VkInstance inst, const PFN_vkGetInstanceProcAddr fp_gipa) {
/* initialize entrypoint function pointers */

#define LOOKUP_GIPA(func, required)                                                        \
    do {                                                                                   \
        icd_term->func = (PFN_vk##func)fp_gipa(inst, "vk" #func);                          \
        if (!icd_term->func && required) {                                                 \
            loader_log((struct loader_instance *)inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0, \
                       loader_platform_get_proc_address_error("vk" #func));                \
            return false;                                                                  \
        }                                                                                  \
    } while (0)

    LOOKUP_GIPA(GetDeviceProcAddr, true);
    LOOKUP_GIPA(DestroyInstance, true);
    LOOKUP_GIPA(EnumeratePhysicalDevices, true);
    LOOKUP_GIPA(GetPhysicalDeviceFeatures, true);
    LOOKUP_GIPA(GetPhysicalDeviceFormatProperties, true);
    LOOKUP_GIPA(GetPhysicalDeviceImageFormatProperties, true);
    LOOKUP_GIPA(CreateDevice, true);
    LOOKUP_GIPA(GetPhysicalDeviceProperties, true);
    LOOKUP_GIPA(GetPhysicalDeviceMemoryProperties, true);
    LOOKUP_GIPA(GetPhysicalDeviceQueueFamilyProperties, true);
    LOOKUP_GIPA(EnumerateDeviceExtensionProperties, true);
    LOOKUP_GIPA(GetPhysicalDeviceSparseImageFormatProperties, true);
    LOOKUP_GIPA(GetPhysicalDeviceSurfaceSupportKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceSurfaceCapabilitiesKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceSurfaceFormatsKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceSurfacePresentModesKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceDisplayPropertiesKHR, false);
    LOOKUP_GIPA(GetDisplayModePropertiesKHR, false);
    LOOKUP_GIPA(CreateDisplayPlaneSurfaceKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceDisplayPlanePropertiesKHR, false);
    LOOKUP_GIPA(GetDisplayPlaneSupportedDisplaysKHR, false);
    LOOKUP_GIPA(CreateDisplayModeKHR, false);
    LOOKUP_GIPA(GetDisplayPlaneCapabilitiesKHR, false);
    LOOKUP_GIPA(DestroySurfaceKHR, false);
    LOOKUP_GIPA(CreateSwapchainKHR, false);
#ifdef VK_USE_PLATFORM_WIN32_KHR
    LOOKUP_GIPA(CreateWin32SurfaceKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceWin32PresentationSupportKHR, false);
#endif
#ifdef VK_USE_PLATFORM_XCB_KHR
    LOOKUP_GIPA(CreateXcbSurfaceKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceXcbPresentationSupportKHR, false);
#endif
#ifdef VK_USE_PLATFORM_XLIB_KHR
    LOOKUP_GIPA(CreateXlibSurfaceKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceXlibPresentationSupportKHR, false);
#endif
#ifdef VK_USE_PLATFORM_MIR_KHR
    LOOKUP_GIPA(CreateMirSurfaceKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceMirPresentationSupportKHR, false);
#endif
#ifdef VK_USE_PLATFORM_WAYLAND_KHR
    LOOKUP_GIPA(CreateWaylandSurfaceKHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceWaylandPresentationSupportKHR, false);
#endif
    LOOKUP_GIPA(CreateSharedSwapchainsKHR, false);

    // KHR_get_physical_device_properties2
    LOOKUP_GIPA(GetPhysicalDeviceFeatures2KHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceProperties2KHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceFormatProperties2KHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceImageFormatProperties2KHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceQueueFamilyProperties2KHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceMemoryProperties2KHR, false);
    LOOKUP_GIPA(GetPhysicalDeviceSparseImageFormatProperties2KHR, false);
    // EXT_debug_marker (items needing a trampoline/terminator)
    LOOKUP_GIPA(DebugMarkerSetObjectTagEXT, false);
    LOOKUP_GIPA(DebugMarkerSetObjectNameEXT, false);

#ifdef VK_USE_PLATFORM_XLIB_XRANDR_EXT
    // EXT_acquire_xlib_display
    LOOKUP_GIPA(AcquireXlibDisplayEXT, false);
    LOOKUP_GIPA(GetRandROutputDisplayEXT, false);
#endif

    // EXT_debug_report
    LOOKUP_GIPA(CreateDebugReportCallbackEXT, false);
    LOOKUP_GIPA(DestroyDebugReportCallbackEXT, false);
    LOOKUP_GIPA(DebugReportMessageEXT, false);

    // EXT_direct_mode_display
    LOOKUP_GIPA(ReleaseDisplayEXT, false);

    // EXT_display_surface_counter
    LOOKUP_GIPA(GetPhysicalDeviceSurfaceCapabilities2EXT, false);

    // NV_external_memory_capabilities
    LOOKUP_GIPA(GetPhysicalDeviceExternalImageFormatPropertiesNV, false);
    // NVX_device_generated_commands
    LOOKUP_GIPA(GetPhysicalDeviceGeneratedCommandsPropertiesNVX, false);

#undef LOOKUP_GIPA

    return true;
}

static void loader_debug_init(void) {
    char *env, *orig;

    if (g_loader_debug > 0) return;

    g_loader_debug = 0;

    /* parse comma-separated debug options */
    orig = env = loader_getenv("VK_LOADER_DEBUG", NULL);
    while (env) {
        char *p = strchr(env, ',');
        size_t len;

        if (p)
            len = p - env;
        else
            len = strlen(env);

        if (len > 0) {
            if (strncmp(env, "all", len) == 0) {
                g_loader_debug = ~0u;
                g_loader_log_msgs = ~0u;
            } else if (strncmp(env, "warn", len) == 0) {
                g_loader_debug |= LOADER_WARN_BIT;
                g_loader_log_msgs |= VK_DEBUG_REPORT_WARNING_BIT_EXT;
            } else if (strncmp(env, "info", len) == 0) {
                g_loader_debug |= LOADER_INFO_BIT;
                g_loader_log_msgs |= VK_DEBUG_REPORT_INFORMATION_BIT_EXT;
            } else if (strncmp(env, "perf", len) == 0) {
                g_loader_debug |= LOADER_PERF_BIT;
                g_loader_log_msgs |= VK_DEBUG_REPORT_PERFORMANCE_WARNING_BIT_EXT;
            } else if (strncmp(env, "error", len) == 0) {
                g_loader_debug |= LOADER_ERROR_BIT;
                g_loader_log_msgs |= VK_DEBUG_REPORT_ERROR_BIT_EXT;
            } else if (strncmp(env, "debug", len) == 0) {
                g_loader_debug |= LOADER_DEBUG_BIT;
                g_loader_log_msgs |= VK_DEBUG_REPORT_DEBUG_BIT_EXT;
            }
        }

        if (!p) break;

        env = p + 1;
    }

    loader_free_getenv(orig, NULL);
}

void loader_initialize(void) {
    // initialize mutexs
    loader_platform_thread_create_mutex(&loader_lock);
    loader_platform_thread_create_mutex(&loader_json_lock);

    // initialize logging
    loader_debug_init();

    // initial cJSON to use alloc callbacks
    cJSON_Hooks alloc_fns = {
        .malloc_fn = loader_instance_tls_heap_alloc, .free_fn = loader_instance_tls_heap_free,
    };
    cJSON_InitHooks(&alloc_fns);
}

struct loader_manifest_files {
    uint32_t count;
    char **filename_list;
};

/**
 * Get next file or dirname given a string list or registry key path
 *
 * \returns
 * A pointer to first char in the next path.
 * The next path (or NULL) in the list is returned in next_path.
 * Note: input string is modified in some cases. PASS IN A COPY!
 */
static char *loader_get_next_path(char *path) {
    uint32_t len;
    char *next;

    if (path == NULL) return NULL;
    next = strchr(path, PATH_SEPARATOR);
    if (next == NULL) {
        len = (uint32_t)strlen(path);
        next = path + len;
    } else {
        *next = '\0';
        next++;
    }

    return next;
}

/**
 * Given a path which is absolute or relative, expand the path if relative or
 * leave the path unmodified if absolute. The base path to prepend to relative
 * paths is given in rel_base.
 *
 * \returns
 * A string in out_fullpath of the full absolute path
 */
static void loader_expand_path(const char *path, const char *rel_base, size_t out_size, char *out_fullpath) {
    if (loader_platform_is_path_absolute(path)) {
        // do not prepend a base to an absolute path
        rel_base = "";
    }

    loader_platform_combine_path(out_fullpath, out_size, rel_base, path, NULL);
}

/**
 * Given a filename (file)  and a list of paths (dir), try to find an existing
 * file in the paths.  If filename already is a path then no
 * searching in the given paths.
 *
 * \returns
 * A string in out_fullpath of either the full path or file.
 */
static void loader_get_fullpath(const char *file, const char *dirs, size_t out_size, char *out_fullpath) {
    if (!loader_platform_is_path(file) && *dirs) {
        char *dirs_copy, *dir, *next_dir;

        dirs_copy = loader_stack_alloc(strlen(dirs) + 1);
        strcpy(dirs_copy, dirs);

        // find if file exists after prepending paths in given list
        for (dir = dirs_copy; *dir && (next_dir = loader_get_next_path(dir)); dir = next_dir) {
            loader_platform_combine_path(out_fullpath, out_size, dir, file, NULL);
            if (loader_platform_file_exists(out_fullpath)) {
                return;
            }
        }
    }

    (void)snprintf(out_fullpath, out_size, "%s", file);
}

/**
 * Read a JSON file into a buffer.
 *
 * \returns
 * A pointer to a cJSON object representing the JSON parse tree.
 * This returned buffer should be freed by caller.
 */
static VkResult loader_get_json(const struct loader_instance *inst, const char *filename, cJSON **json) {
    FILE *file = NULL;
    char *json_buf;
    size_t len;
    VkResult res = VK_SUCCESS;

    if (NULL == json) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0, "loader_get_json: Received invalid JSON file");
        res = VK_ERROR_INITIALIZATION_FAILED;
        goto out;
    }

    *json = NULL;

    file = fopen(filename, "rb");
    if (!file) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0, "loader_get_json: Failed to open JSON file %s", filename);
        res = VK_ERROR_INITIALIZATION_FAILED;
        goto out;
    }
    fseek(file, 0, SEEK_END);
    len = ftell(file);
    fseek(file, 0, SEEK_SET);
    json_buf = (char *)loader_stack_alloc(len + 1);
    if (json_buf == NULL) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_get_json: Failed to allocate space for "
                   "JSON file %s buffer of length %d",
                   filename, len);
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }
    if (fread(json_buf, sizeof(char), len, file) != len) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0, "loader_get_json: Failed to read JSON file %s.", filename);
        res = VK_ERROR_INITIALIZATION_FAILED;
        goto out;
    }
    json_buf[len] = '\0';

    // parse text from file
    *json = cJSON_Parse(json_buf);
    if (*json == NULL) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_get_json: Failed to parse JSON file %s, "
                   "this is usually because something ran out of "
                   "memory.",
                   filename);
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }

out:
    if (NULL != file) {
        fclose(file);
    }

    return res;
}

/**
 * Do a deep copy of the loader_layer_properties structure.
 */
VkResult loader_copy_layer_properties(const struct loader_instance *inst, struct loader_layer_properties *dst,
                                      struct loader_layer_properties *src) {
    uint32_t cnt, i;
    memcpy(dst, src, sizeof(*src));
    dst->instance_extension_list.list = loader_instance_heap_alloc(
        inst, sizeof(VkExtensionProperties) * src->instance_extension_list.count, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (NULL == dst->instance_extension_list.list) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_copy_layer_properties: Failed to allocate space "
                   "for instance extension list of size %d.",
                   src->instance_extension_list.count);
        return VK_ERROR_OUT_OF_HOST_MEMORY;
    }
    dst->instance_extension_list.capacity = sizeof(VkExtensionProperties) * src->instance_extension_list.count;
    memcpy(dst->instance_extension_list.list, src->instance_extension_list.list, dst->instance_extension_list.capacity);
    dst->device_extension_list.list = loader_instance_heap_alloc(
        inst, sizeof(struct loader_dev_ext_props) * src->device_extension_list.count, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (NULL == dst->device_extension_list.list) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_copy_layer_properties: Failed to allocate space "
                   "for device extension list of size %d.",
                   src->device_extension_list.count);
        return VK_ERROR_OUT_OF_HOST_MEMORY;
    }
    memset(dst->device_extension_list.list, 0, sizeof(struct loader_dev_ext_props) * src->device_extension_list.count);

    dst->device_extension_list.capacity = sizeof(struct loader_dev_ext_props) * src->device_extension_list.count;
    memcpy(dst->device_extension_list.list, src->device_extension_list.list, dst->device_extension_list.capacity);
    if (src->device_extension_list.count > 0 && src->device_extension_list.list->entrypoint_count > 0) {
        cnt = src->device_extension_list.list->entrypoint_count;
        dst->device_extension_list.list->entrypoints =
            loader_instance_heap_alloc(inst, sizeof(char *) * cnt, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (NULL == dst->device_extension_list.list->entrypoints) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_copy_layer_properties: Failed to allocate space "
                       "for device extension entrypoint list of size %d.",
                       cnt);
            return VK_ERROR_OUT_OF_HOST_MEMORY;
        }
        memset(dst->device_extension_list.list->entrypoints, 0, sizeof(char *) * cnt);

        for (i = 0; i < cnt; i++) {
            dst->device_extension_list.list->entrypoints[i] = loader_instance_heap_alloc(
                inst, strlen(src->device_extension_list.list->entrypoints[i]) + 1, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
            if (NULL == dst->device_extension_list.list->entrypoints[i]) {
                loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                           "loader_copy_layer_properties: Failed to "
                           "allocate space for device extension entrypoint "
                           "%d name of length",
                           i);
                return VK_ERROR_OUT_OF_HOST_MEMORY;
            }
            strcpy(dst->device_extension_list.list->entrypoints[i], src->device_extension_list.list->entrypoints[i]);
        }
    }

    return VK_SUCCESS;
}

static bool loader_find_layer_name_list(const char *name, const struct loader_layer_list *layer_list) {
    if (!layer_list) return false;
    for (uint32_t j = 0; j < layer_list->count; j++)
        if (!strcmp(name, layer_list->list[j].info.layerName)) return true;
    return false;
}

static bool loader_find_layer_name(const char *name, uint32_t layer_count, const char **layer_list) {
    if (!layer_list) return false;
    for (uint32_t j = 0; j < layer_count; j++)
        if (!strcmp(name, layer_list[j])) return true;
    return false;
}

bool loader_find_layer_name_array(const char *name, uint32_t layer_count, const char layer_list[][VK_MAX_EXTENSION_NAME_SIZE]) {
    if (!layer_list) return false;
    for (uint32_t j = 0; j < layer_count; j++)
        if (!strcmp(name, layer_list[j])) return true;
    return false;
}

/**
 * Searches through an array of layer names (ppp_layer_names) looking for a
 * layer key_name.
 * If not found then simply returns updating nothing.
 * Otherwise, it uses expand_count, expand_names adding them to layer names.
 * Any duplicate (pre-existing) expand_names in layer names are removed.
 * Order is otherwise preserved, with the layer key_name being replaced by the
 * expand_names.
 * @param inst
 * @param layer_count
 * @param ppp_layer_names
 */
VkResult loader_expand_layer_names(struct loader_instance *inst, const char *key_name, uint32_t expand_count,
                                   const char expand_names[][VK_MAX_EXTENSION_NAME_SIZE], uint32_t *layer_count,
                                   char const *const **ppp_layer_names) {
    char const *const *pp_src_layers = *ppp_layer_names;

    if (!loader_find_layer_name(key_name, *layer_count, (char const **)pp_src_layers)) {
        inst->activated_layers_are_std_val = false;
        return VK_SUCCESS;  // didn't find the key_name in the list.
    }

    loader_log(inst, VK_DEBUG_REPORT_INFORMATION_BIT_EXT, 0, "Found meta layer %s, replacing with actual layer group", key_name);

    inst->activated_layers_are_std_val = true;
    char const **pp_dst_layers = loader_instance_heap_alloc(inst, (expand_count + *layer_count - 1) * sizeof(char const *),
                                                            VK_SYSTEM_ALLOCATION_SCOPE_COMMAND);
    if (NULL == pp_dst_layers) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_expand_layer_names:: Failed to allocate space for "
                   "std_validation layer names in pp_dst_layers.");
        return VK_ERROR_OUT_OF_HOST_MEMORY;
    }

    // copy layers from src to dst, stripping key_name and anything in
    // expand_names.
    uint32_t src_index, dst_index = 0;
    for (src_index = 0; src_index < *layer_count; src_index++) {
        if (loader_find_layer_name_array(pp_src_layers[src_index], expand_count, expand_names)) {
            continue;
        }

        if (!strcmp(pp_src_layers[src_index], key_name)) {
            // insert all expand_names in place of key_name
            uint32_t expand_index;
            for (expand_index = 0; expand_index < expand_count; expand_index++) {
                pp_dst_layers[dst_index++] = expand_names[expand_index];
            }
            continue;
        }

        pp_dst_layers[dst_index++] = pp_src_layers[src_index];
    }

    *ppp_layer_names = pp_dst_layers;
    *layer_count = dst_index;

    return VK_SUCCESS;
}

void loader_delete_shadow_inst_layer_names(const struct loader_instance *inst, const VkInstanceCreateInfo *orig,
                                           VkInstanceCreateInfo *ours) {
    /* Free the layer names array iff we had to reallocate it */
    if (orig->ppEnabledLayerNames != ours->ppEnabledLayerNames) {
        loader_instance_heap_free(inst, (void *)ours->ppEnabledLayerNames);
    }
}

void loader_init_std_validation_props(struct loader_layer_properties *props) {
    memset(props, 0, sizeof(struct loader_layer_properties));
    props->type = VK_LAYER_TYPE_META_EXPLICT;
    strncpy(props->info.description, "LunarG Standard Validation Layer", sizeof(props->info.description));
    props->info.implementationVersion = 1;
    strncpy(props->info.layerName, std_validation_str, sizeof(props->info.layerName));
    // TODO what about specVersion? for now insert loader's built version
    props->info.specVersion = VK_MAKE_VERSION(1, 0, VK_HEADER_VERSION);
}

/**
 * Searches through the existing instance layer lists looking for
 * the set of required layer names. If found then it adds a meta property to the
 * layer list.
 * Assumes the required layers are the same for both instance and device lists.
 * @param inst
 * @param layer_count  number of layers in layer_names
 * @param layer_names  array of required layer names
 * @param layer_instance_list
 */
static void loader_add_layer_property_meta(const struct loader_instance *inst, uint32_t layer_count,
                                           const char layer_names[][VK_MAX_EXTENSION_NAME_SIZE],
                                           struct loader_layer_list *layer_instance_list) {
    uint32_t i;
    bool found;
    struct loader_layer_list *layer_list;

    if (0 == layer_count || (!layer_instance_list)) return;
    if (layer_instance_list && (layer_count > layer_instance_list->count)) return;

    layer_list = layer_instance_list;

    found = true;
    if (layer_list == NULL) return;
    for (i = 0; i < layer_count; i++) {
        if (loader_find_layer_name_list(layer_names[i], layer_list)) continue;
        found = false;
        break;
    }

    struct loader_layer_properties *props;
    if (found) {
        props = loader_get_next_layer_property(inst, layer_list);
        if (NULL == props) {
            // Error already triggered in loader_get_next_layer_property.
            return;
        }
        loader_init_std_validation_props(props);
    }
}

// This structure is used to store the json file version
// in a more managable way.
typedef struct {
    uint16_t major;
    uint16_t minor;
    uint16_t patch;
} layer_json_version;

static void loader_read_json_layer(const struct loader_instance *inst, struct loader_layer_list *layer_instance_list,
                                   cJSON *layer_node, layer_json_version version, cJSON *item, cJSON *disable_environment,
                                   bool is_implicit, char *filename) {
    char *temp;
    char *name, *type, *library_path, *api_version;
    char *implementation_version, *description;
    cJSON *ext_item;
    VkExtensionProperties ext_prop;

/*
 * The following are required in the "layer" object:
 * (required) "name"
 * (required) "type"
 * (required) “library_path”
 * (required) “api_version”
 * (required) “implementation_version”
 * (required) “description”
 * (required for implicit layers) “disable_environment”
 */

#define GET_JSON_OBJECT(node, var)                                         \
    {                                                                      \
        var = cJSON_GetObjectItem(node, #var);                             \
        if (var == NULL) {                                                 \
            layer_node = layer_node->next;                                 \
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,           \
                       "Didn't find required layer object %s in manifest " \
                       "JSON file, skipping this layer",                   \
                       #var);                                              \
            return;                                                        \
        }                                                                  \
    }
#define GET_JSON_ITEM(node, var)                                               \
    {                                                                          \
        item = cJSON_GetObjectItem(node, #var);                                \
        if (item == NULL) {                                                    \
            layer_node = layer_node->next;                                     \
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,               \
                       "Didn't find required layer value %s in manifest JSON " \
                       "file, skipping this layer",                            \
                       #var);                                                  \
            return;                                                            \
        }                                                                      \
        temp = cJSON_Print(item);                                              \
        if (temp == NULL) {                                                    \
            layer_node = layer_node->next;                                     \
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,               \
                       "Problem accessing layer value %s in manifest JSON "    \
                       "file, skipping this layer",                            \
                       #var);                                                  \
            return;                                                            \
        }                                                                      \
        temp[strlen(temp) - 1] = '\0';                                         \
        var = loader_stack_alloc(strlen(temp) + 1);                            \
        strcpy(var, &temp[1]);                                                 \
        cJSON_Free(temp);                                                      \
    }
    GET_JSON_ITEM(layer_node, name)
    GET_JSON_ITEM(layer_node, type)
    GET_JSON_ITEM(layer_node, library_path)
    GET_JSON_ITEM(layer_node, api_version)
    GET_JSON_ITEM(layer_node, implementation_version)
    GET_JSON_ITEM(layer_node, description)
    if (is_implicit) {
        GET_JSON_OBJECT(layer_node, disable_environment)
    }
#undef GET_JSON_ITEM
#undef GET_JSON_OBJECT

    // Add list entry
    struct loader_layer_properties *props = NULL;
    if (!strcmp(type, "DEVICE")) {
        loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0, "Device layers are deprecated skipping this layer");
        layer_node = layer_node->next;
        return;
    }
    // Allow either GLOBAL or INSTANCE type interchangeably to handle
    // layers that must work with older loaders
    if (!strcmp(type, "INSTANCE") || !strcmp(type, "GLOBAL")) {
        if (layer_instance_list == NULL) {
            layer_node = layer_node->next;
            return;
        }
        props = loader_get_next_layer_property(inst, layer_instance_list);
        if (NULL == props) {
            // Error already triggered in loader_get_next_layer_property.
            return;
        }
        props->type = (is_implicit) ? VK_LAYER_TYPE_INSTANCE_IMPLICIT : VK_LAYER_TYPE_INSTANCE_EXPLICIT;
    }

    if (props == NULL) {
        layer_node = layer_node->next;
        return;
    }

    strncpy(props->info.layerName, name, sizeof(props->info.layerName));
    props->info.layerName[sizeof(props->info.layerName) - 1] = '\0';

    char *fullpath = props->lib_name;
    char *rel_base;
    if (loader_platform_is_path(library_path)) {
        // A relative or absolute path
        char *name_copy = loader_stack_alloc(strlen(filename) + 1);
        strcpy(name_copy, filename);
        rel_base = loader_platform_dirname(name_copy);
        loader_expand_path(library_path, rel_base, MAX_STRING_SIZE, fullpath);
    } else {
        // A filename which is assumed in a system directory
        loader_get_fullpath(library_path, DEFAULT_VK_LAYERS_PATH, MAX_STRING_SIZE, fullpath);
    }
    props->info.specVersion = loader_make_version(api_version);
    props->info.implementationVersion = atoi(implementation_version);
    strncpy((char *)props->info.description, description, sizeof(props->info.description));
    props->info.description[sizeof(props->info.description) - 1] = '\0';
    if (is_implicit) {
        if (!disable_environment || !disable_environment->child) {
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "Didn't find required layer child value disable_environment"
                       "in manifest JSON file, skipping this layer");
            layer_node = layer_node->next;
            return;
        }
        strncpy(props->disable_env_var.name, disable_environment->child->string, sizeof(props->disable_env_var.name));
        props->disable_env_var.name[sizeof(props->disable_env_var.name) - 1] = '\0';
        strncpy(props->disable_env_var.value, disable_environment->child->valuestring, sizeof(props->disable_env_var.value));
        props->disable_env_var.value[sizeof(props->disable_env_var.value) - 1] = '\0';
    }

/**
* Now get all optional items and objects and put in list:
* functions
* instance_extensions
* device_extensions
* enable_environment (implicit layers only)
*/
#define GET_JSON_OBJECT(node, var) \
    { var = cJSON_GetObjectItem(node, #var); }
#define GET_JSON_ITEM(node, var)                            \
    {                                                       \
        item = cJSON_GetObjectItem(node, #var);             \
        if (item != NULL) {                                 \
            temp = cJSON_Print(item);                       \
            if (temp != NULL) {                             \
                temp[strlen(temp) - 1] = '\0';              \
                var = loader_stack_alloc(strlen(temp) + 1); \
                strcpy(var, &temp[1]);                      \
                cJSON_Free(temp);                           \
            }                                               \
        }                                                   \
    }

    cJSON *instance_extensions, *device_extensions, *functions, *enable_environment;
    cJSON *entrypoints = NULL;
    char *vkGetInstanceProcAddr = NULL;
    char *vkGetDeviceProcAddr = NULL;
    char *vkNegotiateLoaderLayerInterfaceVersion = NULL;
    char *spec_version = NULL;
    char **entry_array = NULL;
    entrypoints = NULL;
    int i, j;

    // Layer interface functions
    //    vkGetInstanceProcAddr
    //    vkGetDeviceProcAddr
    //    vkNegotiateLoaderLayerInterfaceVersion (starting with JSON file 1.1.0)
    GET_JSON_OBJECT(layer_node, functions)
    if (functions != NULL) {
        if (version.major > 1 || version.minor >= 1) {
            GET_JSON_ITEM(functions, vkNegotiateLoaderLayerInterfaceVersion)
            if (vkNegotiateLoaderLayerInterfaceVersion != NULL)
                strncpy(props->functions.str_negotiate_interface, vkNegotiateLoaderLayerInterfaceVersion,
                        sizeof(props->functions.str_negotiate_interface));
            props->functions.str_negotiate_interface[sizeof(props->functions.str_negotiate_interface) - 1] = '\0';
        } else {
            props->functions.str_negotiate_interface[0] = '\0';
        }
        GET_JSON_ITEM(functions, vkGetInstanceProcAddr)
        GET_JSON_ITEM(functions, vkGetDeviceProcAddr)
        if (vkGetInstanceProcAddr != NULL) {
            strncpy(props->functions.str_gipa, vkGetInstanceProcAddr, sizeof(props->functions.str_gipa));
            if (version.major > 1 || version.minor >= 1) {
                loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                           "Indicating layer-specific vkGetInstanceProcAddr "
                           "function is deprecated starting with JSON file "
                           "version 1.1.0.  Instead, use the new "
                           "vkNegotiateLayerInterfaceVersion function to "
                           "return the GetInstanceProcAddr function for this"
                           "layer");
            }
        }
        props->functions.str_gipa[sizeof(props->functions.str_gipa) - 1] = '\0';
        if (vkGetDeviceProcAddr != NULL) {
            strncpy(props->functions.str_gdpa, vkGetDeviceProcAddr, sizeof(props->functions.str_gdpa));
            if (version.major > 1 || version.minor >= 1) {
                loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                           "Indicating layer-specific vkGetDeviceProcAddr "
                           "function is deprecated starting with JSON file "
                           "version 1.1.0.  Instead, use the new "
                           "vkNegotiateLayerInterfaceVersion function to "
                           "return the GetDeviceProcAddr function for this"
                           "layer");
            }
        }
        props->functions.str_gdpa[sizeof(props->functions.str_gdpa) - 1] = '\0';
    }

    // instance_extensions
    //   array of {
    //     name
    //     spec_version
    //   }
    GET_JSON_OBJECT(layer_node, instance_extensions)
    if (instance_extensions != NULL) {
        int count = cJSON_GetArraySize(instance_extensions);
        for (i = 0; i < count; i++) {
            ext_item = cJSON_GetArrayItem(instance_extensions, i);
            GET_JSON_ITEM(ext_item, name)
            if (name != NULL) {
                strncpy(ext_prop.extensionName, name, sizeof(ext_prop.extensionName));
                ext_prop.extensionName[sizeof(ext_prop.extensionName) - 1] = '\0';
            }
            GET_JSON_ITEM(ext_item, spec_version)
            if (NULL != spec_version) {
                ext_prop.specVersion = atoi(spec_version);
            } else {
                ext_prop.specVersion = 0;
            }
            bool ext_unsupported = wsi_unsupported_instance_extension(&ext_prop);
            if (!ext_unsupported) {
                loader_add_to_ext_list(inst, &props->instance_extension_list, 1, &ext_prop);
            }
        }
    }

    // device_extensions
    //   array of {
    //     name
    //     spec_version
    //     entrypoints
    //   }
    GET_JSON_OBJECT(layer_node, device_extensions)
    if (device_extensions != NULL) {
        int count = cJSON_GetArraySize(device_extensions);
        for (i = 0; i < count; i++) {
            ext_item = cJSON_GetArrayItem(device_extensions, i);
            GET_JSON_ITEM(ext_item, name)
            GET_JSON_ITEM(ext_item, spec_version)
            if (name != NULL) {
                strncpy(ext_prop.extensionName, name, sizeof(ext_prop.extensionName));
                ext_prop.extensionName[sizeof(ext_prop.extensionName) - 1] = '\0';
            }
            if (NULL != spec_version) {
                ext_prop.specVersion = atoi(spec_version);
            } else {
                ext_prop.specVersion = 0;
            }
            // entrypoints = cJSON_GetObjectItem(ext_item, "entrypoints");
            GET_JSON_OBJECT(ext_item, entrypoints)
            int entry_count;
            if (entrypoints == NULL) {
                loader_add_to_dev_ext_list(inst, &props->device_extension_list, &ext_prop, 0, NULL);
                continue;
            }
            entry_count = cJSON_GetArraySize(entrypoints);
            if (entry_count) {
                entry_array = (char **)loader_stack_alloc(sizeof(char *) * entry_count);
            }
            for (j = 0; j < entry_count; j++) {
                ext_item = cJSON_GetArrayItem(entrypoints, j);
                if (ext_item != NULL) {
                    temp = cJSON_Print(ext_item);
                    if (NULL == temp) {
                        entry_array[j] = NULL;
                        continue;
                    }
                    temp[strlen(temp) - 1] = '\0';
                    entry_array[j] = loader_stack_alloc(strlen(temp) + 1);
                    strcpy(entry_array[j], &temp[1]);
                    cJSON_Free(temp);
                }
            }
            loader_add_to_dev_ext_list(inst, &props->device_extension_list, &ext_prop, entry_count, entry_array);
        }
    }
    if (is_implicit) {
        GET_JSON_OBJECT(layer_node, enable_environment)

        // enable_environment is optional
        if (enable_environment) {
            strncpy(props->enable_env_var.name, enable_environment->child->string, sizeof(props->enable_env_var.name));
            props->enable_env_var.name[sizeof(props->enable_env_var.name) - 1] = '\0';
            strncpy(props->enable_env_var.value, enable_environment->child->valuestring, sizeof(props->enable_env_var.value));
            props->enable_env_var.value[sizeof(props->enable_env_var.value) - 1] = '\0';
        }
    }
#undef GET_JSON_ITEM
#undef GET_JSON_OBJECT
}

static inline bool is_valid_layer_json_version(const layer_json_version *layer_json) {
    // Supported versions are: 1.0.0, 1.0.1, and 1.1.0.
    if ((layer_json->major == 1 && layer_json->minor == 1 && layer_json->patch == 0) ||
        (layer_json->major == 1 && layer_json->minor == 0 && layer_json->patch < 2)) {
        return true;
    }
    return false;
}

static inline bool layer_json_supports_layers_tag(const layer_json_version *layer_json) {
    // Supported versions started in 1.0.1, so anything newer
    if ((layer_json->major > 1 || layer_json->minor > 0 || layer_json->patch > 1)) {
        return true;
    }
    return false;
}

/**
 * Given a cJSON struct (json) of the top level JSON object from layer manifest
 * file, add entry to the layer_list. Fill out the layer_properties in this list
 * entry from the input cJSON object.
 *
 * \returns
 * void
 * layer_list has a new entry and initialized accordingly.
 * If the json input object does not have all the required fields no entry
 * is added to the list.
 */
static void loader_add_layer_properties(const struct loader_instance *inst, struct loader_layer_list *layer_instance_list,
                                        cJSON *json, bool is_implicit, char *filename) {
    // The following Fields in layer manifest file that are required:
    //   - “file_format_version”
    //   - If more than one "layer" object are used, then the "layers" array is
    //     requred

    cJSON *item, *layers_node, *layer_node;
    layer_json_version json_version;
    char *vers_tok;
    cJSON *disable_environment = NULL;
    item = cJSON_GetObjectItem(json, "file_format_version");
    if (item == NULL) {
        return;
    }
    char *file_vers = cJSON_PrintUnformatted(item);
    if (NULL == file_vers) {
        return;
    }
    loader_log(inst, VK_DEBUG_REPORT_INFORMATION_BIT_EXT, 0, "Found manifest file %s, version %s", filename, file_vers);
    // Get the major/minor/and patch as integers for easier comparison
    vers_tok = strtok(file_vers, ".\"\n\r");
    if (NULL != vers_tok) {
        json_version.major = (uint16_t)atoi(vers_tok);
        vers_tok = strtok(NULL, ".\"\n\r");
        if (NULL != vers_tok) {
            json_version.minor = (uint16_t)atoi(vers_tok);
            vers_tok = strtok(NULL, ".\"\n\r");
            if (NULL != vers_tok) {
                json_version.patch = (uint16_t)atoi(vers_tok);
            }
        }
    }

    if (!is_valid_layer_json_version(&json_version)) {
        loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                   "loader_add_layer_properties: %s invalid layer "
                   " manifest file version %d.%d.%d.  May cause errors.",
                   filename, json_version.major, json_version.minor, json_version.patch);
    }
    cJSON_Free(file_vers);

    // If "layers" is present, read in the array of layer objects
    layers_node = cJSON_GetObjectItem(json, "layers");
    if (layers_node != NULL) {
        int numItems = cJSON_GetArraySize(layers_node);
        if (!layer_json_supports_layers_tag(&json_version)) {
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "loader_add_layer_properties: \'layers\' tag not "
                       "supported until file version 1.0.1, but %s is "
                       "reporting version %s",
                       filename, file_vers);
        }
        for (int curLayer = 0; curLayer < numItems; curLayer++) {
            layer_node = cJSON_GetArrayItem(layers_node, curLayer);
            if (layer_node == NULL) {
                loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                           "loader_add_layer_properties: Can not find "
                           "\'layers\' array element %d object in manifest "
                           "JSON file %s.  Skipping this file",
                           curLayer, filename);
                return;
            }
            loader_read_json_layer(inst, layer_instance_list, layer_node, json_version, item, disable_environment, is_implicit,
                                   filename);
        }
    } else {
        // Otherwise, try to read in individual layers
        layer_node = cJSON_GetObjectItem(json, "layer");
        if (layer_node == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "loader_add_layer_properties: Can not find \'layer\' "
                       "object in manifest JSON file %s.  Skipping this file.",
                       filename);
            return;
        }
        // Loop through all "layer" objects in the file to get a count of them
        // first.
        uint16_t layer_count = 0;
        cJSON *tempNode = layer_node;
        do {
            tempNode = tempNode->next;
            layer_count++;
        } while (tempNode != NULL);

        // Throw a warning if we encounter multiple "layer" objects in file
        // versions newer than 1.0.0.  Having multiple objects with the same
        // name at the same level is actually a JSON standard violation.
        if (layer_count > 1 && layer_json_supports_layers_tag(&json_version)) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_add_layer_properties: Multiple \'layer\' nodes"
                       " are deprecated starting in file version \"1.0.1\".  "
                       "Please use \'layers\' : [] array instead in %s.",
                       filename);
        } else {
            do {
                loader_read_json_layer(inst, layer_instance_list, layer_node, json_version, item, disable_environment, is_implicit,
                                       filename);
                layer_node = layer_node->next;
            } while (layer_node != NULL);
        }
    }
    return;
}

/**
 * Find the Vulkan library manifest files.
 *
 * This function scans the "location" or "env_override" directories/files
 * for a list of JSON manifest files.  If env_override is non-NULL
 * and has a valid value. Then the location is ignored.  Otherwise
 * location is used to look for manifest files. The location
 * is interpreted as  Registry path on Windows and a directory path(s)
 * on Linux. "home_location" is an additional directory in the users home
 * directory to look at. It is expanded into the dir path
 * $XDG_DATA_HOME/home_location or $HOME/.local/share/home_location depending
 * on environment variables. This "home_location" is only used on Linux.
 *
 * \returns
 * VKResult
 * A string list of manifest files to be opened in out_files param.
 * List has a pointer to string for each manifest filename.
 * When done using the list in out_files, pointers should be freed.
 * Location or override  string lists can be either files or directories as
 *follows:
 *            | location | override
 * --------------------------------
 * Win ICD    | files    | files
 * Win Layer  | files    | dirs
 * Linux ICD  | dirs     | files
 * Linux Layer| dirs     | dirs
 */
static VkResult loader_get_manifest_files(const struct loader_instance *inst, const char *env_override, const char *source_override,
                                          bool is_layer, bool warn_if_not_present, const char *location, const char *relative_location,
                                          struct loader_manifest_files *out_files) {
    const char * override = NULL;
    char *override_getenv = NULL;
    char *loc, *orig_loc = NULL;
    char *reg = NULL;
    char *file, *next_file, *name;
    size_t alloced_count = 64;
    char full_path[2048];
    DIR *sysdir = NULL;
    bool list_is_dirs = false;
    struct dirent *dent;
    VkResult res = VK_SUCCESS;

    out_files->count = 0;
    out_files->filename_list = NULL;

    if (source_override != NULL) {
        override = source_override;
    } else if (env_override != NULL) {
#if !defined(_WIN32)
        if (geteuid() != getuid() || getegid() != getgid()) {
            /* Don't allow setuid apps to use the env var: */
            env_override = NULL;
        }
#endif
        if (env_override != NULL) {
            override = override_getenv = loader_getenv(env_override, inst);
        }
    }

#if !defined(_WIN32)
    if (relative_location == NULL) {
#else
    relative_location = NULL;
    if (location == NULL) {
#endif
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_get_manifest_files: Can not get manifest files with "
                   "NULL location, env_override=%s",
                   (env_override != NULL) ? env_override : "");
        res = VK_ERROR_INITIALIZATION_FAILED;
        goto out;
    }

#if defined(_WIN32)
    list_is_dirs = (is_layer && override != NULL) ? true : false;
#else
    list_is_dirs = (override == NULL || is_layer) ? true : false;
#endif
    // Make a copy of the input we are using so it is not modified
    // Also handle getting the location(s) from registry on Windows
    if (override == NULL) {
        size_t loc_size = 0;
#if !defined(_WIN32)
        const char *xdgconfdirs = secure_getenv("XDG_CONFIG_DIRS");
        const char *xdgdatadirs = secure_getenv("XDG_DATA_DIRS");
        if (xdgconfdirs == NULL || xdgconfdirs[0] == '\0')
            xdgconfdirs = "/etc/xdg";
        if (xdgdatadirs == NULL || xdgdatadirs[0] == '\0')
            xdgdatadirs = "/usr/local/share:/usr/share";
        const size_t rel_size = strlen(relative_location);
        // Leave space for trailing separators
        loc_size += strlen(xdgconfdirs) + strlen(xdgdatadirs) + 2*rel_size + 2;
        for (const char *x = xdgconfdirs; *x; ++x)
            if (*x == PATH_SEPARATOR) loc_size += rel_size;
        for (const char *x = xdgdatadirs; *x; ++x)
            if (*x == PATH_SEPARATOR) loc_size += rel_size;
        loc_size += strlen(SYSCONFDIR) + rel_size + 1;
#if defined(EXTRASYSCONFDIR)
        loc_size += strlen(EXTRASYSCONFDIR) + rel_size + 1;
#endif
#else
        loc_size += strlen(location) + 1;
#endif
        loc = loader_stack_alloc(loc_size);
        if (loc == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_get_manifest_files: Failed to allocate "
                       "%d bytes for manifest file location.",
                       loc_size);
            res = VK_ERROR_OUT_OF_HOST_MEMORY;
            goto out;
        }
        char *loc_write = loc;
#if !defined(_WIN32)
        const char *loc_read;
        size_t start, stop;

        loc_read = &xdgconfdirs[0];
        start = 0;
        while (loc_read[start] != '\0') {
            while (loc_read[start] == PATH_SEPARATOR) {
                start++;
            }
            stop = start;
            while (loc_read[stop] != PATH_SEPARATOR && loc_read[stop] != '\0') {
                stop++;
            }
            const size_t s = stop - start;
            if (s) {
                memcpy(loc_write, &loc_read[start], s);
                loc_write += s;
                memcpy(loc_write, relative_location, rel_size);
                loc_write += rel_size;
                *loc_write++ = PATH_SEPARATOR;
                start = stop;
            }
        }

        memcpy(loc_write, SYSCONFDIR, strlen(SYSCONFDIR));
        loc_write += strlen(SYSCONFDIR);
        memcpy(loc_write, relative_location, rel_size);
        loc_write += rel_size;
        *loc_write++ = PATH_SEPARATOR;

#if defined(EXTRASYSCONFDIR)
        memcpy(loc_write, EXTRASYSCONFDIR, strlen(EXTRASYSCONFDIR));
        loc_write += strlen(EXTRASYSCONFDIR);
        memcpy(loc_write, relative_location, rel_size);
        loc_write += rel_size;
        *loc_write++ = PATH_SEPARATOR;
#endif

        loc_read = &xdgdatadirs[0];
        start = 0;
        while (loc_read[start] != '\0') {
            while (loc_read[start] == PATH_SEPARATOR) {
                start++;
            }
            stop = start;
            while (loc_read[stop] != PATH_SEPARATOR && loc_read[stop] != '\0') {
                stop++;
            }
            const size_t s = stop - start;
            if (s) {
                memcpy(loc_write, &loc_read[start], s);
                loc_write += s;
                memcpy(loc_write, relative_location, rel_size);
                loc_write += rel_size;
                *loc_write++ = PATH_SEPARATOR;
                start = stop;
            }
        }

        --loc_write;
#else
        memcpy(loc_write, location, strlen(location));
        loc_write += strlen(location);
#endif
        assert(loc_write - loc < (ptrdiff_t)loc_size);
        *loc_write = '\0';

#if defined(_WIN32)
        VkResult reg_result = loaderGetRegistryFiles(inst, loc, &reg);
        if (VK_SUCCESS != reg_result || NULL == reg) {
            if (!is_layer) {
                loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                           "loader_get_manifest_files: Registry lookup failed "
                           "to get ICD manifest files.  Possibly missing Vulkan"
                           " driver?");
                if (VK_SUCCESS == reg_result || VK_ERROR_OUT_OF_HOST_MEMORY == reg_result) {
                    res = reg_result;
                } else {
                    res = VK_ERROR_INCOMPATIBLE_DRIVER;
                }
            } else {
                if (warn_if_not_present) {
                    // This is only a warning for layers
                    loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                               "loader_get_manifest_files: Registry lookup failed "
                               "to get layer manifest files.");
                }
                if (reg_result == VK_ERROR_OUT_OF_HOST_MEMORY) {
                    res = reg_result;
                } else {
                    // Return success for now since it's not critical for layers
                    res = VK_SUCCESS;
                }
            }
            goto out;
        }
        orig_loc = loc;
        loc = reg;
#endif
    } else {
        loc = loader_stack_alloc(strlen(override) + 1);
        if (loc == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_get_manifest_files: Failed to allocate space for "
                       "override environment variable of length %d",
                       strlen(override) + 1);
            res = VK_ERROR_OUT_OF_HOST_MEMORY;
            goto out;
        }
        strcpy(loc, override);
    }

    // Print out the paths being searched if debugging is enabled
    loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Searching the following paths for manifest files: %s\n", loc);

    file = loc;
    while (*file) {
        next_file = loader_get_next_path(file);
        if (list_is_dirs) {
            sysdir = opendir(file);
            name = NULL;
            if (sysdir) {
                dent = readdir(sysdir);
                if (dent == NULL) break;
                name = &(dent->d_name[0]);
                loader_get_fullpath(name, file, sizeof(full_path), full_path);
                name = full_path;
            }
        } else {
#if defined(_WIN32)
            name = file;
#else
            // only Linux has relative paths
            char *dir;
            // make a copy of location so it isn't modified
            dir = loader_stack_alloc(strlen(loc) + 1);
            if (dir == NULL) {
                loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                           "loader_get_manifest_files: Failed to allocate "
                           "space for relative location path length %d",
                           strlen(loc) + 1);
                goto out;
            }
            strcpy(dir, loc);

            loader_get_fullpath(file, dir, sizeof(full_path), full_path);

            name = full_path;
#endif
        }
        while (name) {
            /* Look for files ending with ".json" suffix */
            uint32_t nlen = (uint32_t)strlen(name);
            const char *suf = name + nlen - 5;
            if ((nlen > 5) && !strncmp(suf, ".json", 5)) {
                if (out_files->count == 0) {
                    out_files->filename_list =
                        loader_instance_heap_alloc(inst, alloced_count * sizeof(char *), VK_SYSTEM_ALLOCATION_SCOPE_COMMAND);
                } else if (out_files->count == alloced_count) {
                    out_files->filename_list =
                        loader_instance_heap_realloc(inst, out_files->filename_list, alloced_count * sizeof(char *),
                                                     alloced_count * sizeof(char *) * 2, VK_SYSTEM_ALLOCATION_SCOPE_COMMAND);
                    alloced_count *= 2;
                }
                if (out_files->filename_list == NULL) {
                    loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                               "loader_get_manifest_files: Failed to allocate "
                               "space for manifest file name list");
                    res = VK_ERROR_OUT_OF_HOST_MEMORY;
                    goto out;
                }
                out_files->filename_list[out_files->count] =
                    loader_instance_heap_alloc(inst, strlen(name) + 1, VK_SYSTEM_ALLOCATION_SCOPE_COMMAND);
                if (out_files->filename_list[out_files->count] == NULL) {
                    loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                               "loader_get_manifest_files: Failed to allocate "
                               "space for manifest file %d list",
                               out_files->count);
                    res = VK_ERROR_OUT_OF_HOST_MEMORY;
                    goto out;
                }
                strcpy(out_files->filename_list[out_files->count], name);
                out_files->count++;
            } else if (!list_is_dirs) {
                loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0, "Skipping manifest file %s, file name must end in .json",
                           name);
            }
            if (list_is_dirs) {
                dent = readdir(sysdir);
                if (dent == NULL) {
                    break;
                }
                name = &(dent->d_name[0]);
                loader_get_fullpath(name, file, sizeof(full_path), full_path);
                name = full_path;
            } else {
                break;
            }
        }
        if (sysdir) {
            closedir(sysdir);
            sysdir = NULL;
        }
        file = next_file;
#if !defined(_WIN32)
        if (relative_location != NULL && (next_file == NULL || *next_file == '\0') && override == NULL) {
            char *xdgdatahome = secure_getenv("XDG_DATA_HOME");
            size_t len;
            if (xdgdatahome != NULL) {
                size_t alloc_len = strlen(xdgdatahome) + 2 + strlen(relative_location);
                char *home_loc = loader_stack_alloc(alloc_len);
                if (home_loc == NULL) {
                    loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                               "loader_get_manifest_files: Failed to allocate "
                               "space for manifest file XDG Home location");
                    res = VK_ERROR_OUT_OF_HOST_MEMORY;
                    goto out;
                }
                strcpy(home_loc, xdgdatahome);
                // Add directory separator if needed
                if (relative_location[0] != DIRECTORY_SYMBOL) {
                    len = strlen(home_loc);
                    home_loc[len] = DIRECTORY_SYMBOL;
                    home_loc[len + 1] = '\0';
                }
                strncat(home_loc, relative_location, alloc_len);
                file = home_loc;
                next_file = loader_get_next_path(file);
                relative_location = NULL;

                loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Searching the following path for manifest files: %s\n",
                           home_loc);
                list_is_dirs = true;

            } else {
                char *home = secure_getenv("HOME");
                if (home != NULL) {
                    size_t alloc_len = strlen(home) + 16 + strlen(relative_location);
                    char *home_loc = loader_stack_alloc(alloc_len);
                    if (home_loc == NULL) {
                        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                                   "loader_get_manifest_files: Failed to allocate "
                                   "space for manifest file Home location");
                        res = VK_ERROR_OUT_OF_HOST_MEMORY;
                        goto out;
                    }
                    strncpy(home_loc, home, alloc_len);

                    len = strlen(home);
                    if (home[len] != DIRECTORY_SYMBOL) {
                        home_loc[len] = DIRECTORY_SYMBOL;
                        home_loc[len + 1] = '\0';
                    }
                    strncat(home_loc, ".local/share", alloc_len);

                    if (relative_location[0] != DIRECTORY_SYMBOL) {
                        len = strlen(home_loc);
                        home_loc[len] = DIRECTORY_SYMBOL;
                        home_loc[len + 1] = '\0';
                    }
                    strncat(home_loc, relative_location, alloc_len);
                    file = home_loc;
                    next_file = loader_get_next_path(file);
                    relative_location = NULL;

                    loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Searching the following path for manifest files: %s\n",
                               home_loc);
                    list_is_dirs = true;
                } else {
                    // without knowing HOME, we just.. give up
                }
            }
        }
#endif
    }

out:
    if (VK_SUCCESS != res && NULL != out_files->filename_list) {
        for (uint32_t remove = 0; remove < out_files->count; remove++) {
            loader_instance_heap_free(inst, out_files->filename_list[remove]);
        }
        loader_instance_heap_free(inst, out_files->filename_list);
        out_files->count = 0;
        out_files->filename_list = NULL;
    }

    if (NULL != sysdir) {
        closedir(sysdir);
    }

    if (override_getenv != NULL) {
        loader_free_getenv(override_getenv, inst);
    }

    if (NULL != reg && reg != orig_loc) {
        loader_instance_heap_free(inst, reg);
    }
    return res;
}

void loader_init_icd_lib_list() {}

void loader_destroy_icd_lib_list() {}
/**
 * Try to find the Vulkan ICD driver(s).
 *
 * This function scans the default system loader path(s) or path
 * specified by the \c VK_ICD_FILENAMES environment variable in
 * order to find loadable VK ICDs manifest files. From these
 * manifest files it finds the ICD libraries.
 *
 * \returns
 * Vulkan result
 * (on result == VK_SUCCESS) a list of icds that were discovered
 */
VkResult loader_icd_scan(const struct loader_instance *inst, struct loader_icd_tramp_list *icd_tramp_list) {
    char *file_str;
    uint16_t file_major_vers = 0;
    uint16_t file_minor_vers = 0;
    uint16_t file_patch_vers = 0;
    char *vers_tok;
    struct loader_manifest_files manifest_files;
    VkResult res = VK_SUCCESS;
    bool lockedMutex = false;
    cJSON *json = NULL;
    uint32_t num_good_icds = 0;

    memset(&manifest_files, 0, sizeof(struct loader_manifest_files));

    res = loader_scanned_icd_init(inst, icd_tramp_list);
    if (VK_SUCCESS != res) {
        goto out;
    }

    // Get a list of manifest files for ICDs
    res = loader_get_manifest_files(inst, "VK_ICD_FILENAMES", NULL, false, true, DEFAULT_VK_DRIVERS_INFO, RELATIVE_VK_DRIVERS_INFO,
                                    &manifest_files);
    if (VK_SUCCESS != res || manifest_files.count == 0) {
        goto out;
    }
    loader_platform_thread_lock_mutex(&loader_json_lock);
    lockedMutex = true;
    for (uint32_t i = 0; i < manifest_files.count; i++) {
        file_str = manifest_files.filename_list[i];
        if (file_str == NULL) {
            continue;
        }

        res = loader_get_json(inst, file_str, &json);
        if (VK_ERROR_OUT_OF_HOST_MEMORY == res) {
            break;
        } else if (VK_SUCCESS != res || NULL == json) {
            continue;
        }

        cJSON *item, *itemICD;
        item = cJSON_GetObjectItem(json, "file_format_version");
        if (item == NULL) {
            if (num_good_icds == 0) {
                res = VK_ERROR_INITIALIZATION_FAILED;
            }
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "loader_icd_scan: ICD JSON %s does not have a"
                       " \'file_format_version\' field. Skipping ICD JSON.",
                       file_str);
            cJSON_Delete(json);
            json = NULL;
            continue;
        }
        char *file_vers = cJSON_Print(item);
        if (NULL == file_vers) {
            // Only reason the print can fail is if there was an allocation
            // issue
            if (num_good_icds == 0) {
                res = VK_ERROR_OUT_OF_HOST_MEMORY;
            }
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "loader_icd_scan: Failed retrieving ICD JSON %s"
                       " \'file_format_version\' field.  Skipping ICD JSON",
                       file_str);
            cJSON_Delete(json);
            json = NULL;
            continue;
        }
        loader_log(inst, VK_DEBUG_REPORT_INFORMATION_BIT_EXT, 0, "Found ICD manifest file %s, version %s", file_str, file_vers);
        // Get the major/minor/and patch as integers for easier comparison
        vers_tok = strtok(file_vers, ".\"\n\r");
        if (NULL != vers_tok) {
            file_major_vers = (uint16_t)atoi(vers_tok);
            vers_tok = strtok(NULL, ".\"\n\r");
            if (NULL != vers_tok) {
                file_minor_vers = (uint16_t)atoi(vers_tok);
                vers_tok = strtok(NULL, ".\"\n\r");
                if (NULL != vers_tok) {
                    file_patch_vers = (uint16_t)atoi(vers_tok);
                }
            }
        }
        if (file_major_vers != 1 || file_minor_vers != 0 || file_patch_vers > 1)
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "loader_icd_scan: Unexpected manifest file version "
                       "(expected 1.0.0 or 1.0.1), may cause errors");
        cJSON_Free(file_vers);
        itemICD = cJSON_GetObjectItem(json, "ICD");
        if (itemICD != NULL) {
            item = cJSON_GetObjectItem(itemICD, "library_path");
            if (item != NULL) {
                char *temp = cJSON_Print(item);
                if (!temp || strlen(temp) == 0) {
                    if (num_good_icds == 0) {
                        res = VK_ERROR_OUT_OF_HOST_MEMORY;
                    }
                    loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                               "loader_icd_scan: Failed retrieving ICD JSON %s"
                               " \'library_path\' field.  Skipping ICD JSON.",
                               file_str);
                    cJSON_Free(temp);
                    cJSON_Delete(json);
                    json = NULL;
                    continue;
                }
                // strip out extra quotes
                temp[strlen(temp) - 1] = '\0';
                char *library_path = loader_stack_alloc(strlen(temp) + 1);
                if (NULL == library_path) {
                    loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                               "loader_icd_scan: Failed to allocate space for "
                               "ICD JSON %s \'library_path\' value.  Skipping "
                               "ICD JSON.",
                               file_str);
                    res = VK_ERROR_OUT_OF_HOST_MEMORY;
                    cJSON_Free(temp);
                    cJSON_Delete(json);
                    json = NULL;
                    goto out;
                }
                strcpy(library_path, &temp[1]);
                cJSON_Free(temp);
                if (strlen(library_path) == 0) {
                    loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                               "loader_icd_scan: ICD JSON %s \'library_path\'"
                               " field is empty.  Skipping ICD JSON.",
                               file_str);
                    cJSON_Delete(json);
                    json = NULL;
                    continue;
                }
                char fullpath[MAX_STRING_SIZE];
                // Print out the paths being searched if debugging is enabled
                loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Searching for ICD drivers named %s, using default dir %s",
                           library_path, DEFAULT_VK_DRIVERS_PATH);
                if (loader_platform_is_path(library_path)) {
                    // a relative or absolute path
                    char *name_copy = loader_stack_alloc(strlen(file_str) + 1);
                    char *rel_base;
                    strcpy(name_copy, file_str);
                    rel_base = loader_platform_dirname(name_copy);
                    loader_expand_path(library_path, rel_base, sizeof(fullpath), fullpath);
                } else {
                    // a filename which is assumed in a system directory
                    loader_get_fullpath(library_path, DEFAULT_VK_DRIVERS_PATH, sizeof(fullpath), fullpath);
                }

                uint32_t vers = 0;
                item = cJSON_GetObjectItem(itemICD, "api_version");
                if (item != NULL) {
                    temp = cJSON_Print(item);
                    if (NULL == temp) {
                        loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                                   "loader_icd_scan: Failed retrieving ICD JSON %s"
                                   " \'api_version\' field.  Skipping ICD JSON.",
                                   file_str);

                        // Only reason the print can fail is if there was an
                        // allocation issue
                        if (num_good_icds == 0) {
                            res = VK_ERROR_OUT_OF_HOST_MEMORY;
                        }

                        cJSON_Free(temp);
                        cJSON_Delete(json);
                        json = NULL;
                        continue;
                    }
                    vers = loader_make_version(temp);
                    cJSON_Free(temp);
                } else {
                    loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                               "loader_icd_scan: ICD JSON %s does not have an"
                               " \'api_version\' field.",
                               file_str);
                }

                res = loader_scanned_icd_add(inst, icd_tramp_list, fullpath, vers);
                if (VK_SUCCESS != res) {
                    loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                               "loader_icd_scan: Failed to add ICD JSON %s. "
                               " Skipping ICD JSON.",
                               fullpath);
                    continue;
                }
                num_good_icds++;
            } else {
                loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                           "loader_icd_scan: Failed to find \'library_path\' "
                           "object in ICD JSON file %s.  Skipping ICD JSON.",
                           file_str);
            }
        } else {
            loader_log(inst, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "loader_icd_scan: Can not find \'ICD\' object in ICD JSON "
                       "file %s.  Skipping ICD JSON",
                       file_str);
        }

        cJSON_Delete(json);
        json = NULL;
    }

out:

    if (NULL != json) {
        cJSON_Delete(json);
    }
    if (NULL != manifest_files.filename_list) {
        for (uint32_t i = 0; i < manifest_files.count; i++) {
            if (NULL != manifest_files.filename_list[i]) {
                loader_instance_heap_free(inst, manifest_files.filename_list[i]);
            }
        }
        loader_instance_heap_free(inst, manifest_files.filename_list);
    }
    if (lockedMutex) {
        loader_platform_thread_unlock_mutex(&loader_json_lock);
    }
    return res;
}

void loader_layer_scan(const struct loader_instance *inst, struct loader_layer_list *instance_layers) {
    char *file_str;
    struct loader_manifest_files manifest_files[2];  // [0] = explicit, [1] = implicit
    cJSON *json;
    uint32_t implicit;
    bool lockedMutex = false;

    memset(manifest_files, 0, sizeof(struct loader_manifest_files) * 2);

    // Get a list of manifest files for explicit layers
    if (VK_SUCCESS != loader_get_manifest_files(inst, LAYERS_PATH_ENV, LAYERS_SOURCE_PATH, true, true, DEFAULT_VK_ELAYERS_INFO,
                                                RELATIVE_VK_ELAYERS_INFO, &manifest_files[0])) {
        goto out;
    }

    // Get a list of manifest files for any implicit layers
    // Pass NULL for environment variable override - implicit layers are not
    // overridden by LAYERS_PATH_ENV
    if (VK_SUCCESS != loader_get_manifest_files(inst, NULL, NULL, true, false, DEFAULT_VK_ILAYERS_INFO, RELATIVE_VK_ILAYERS_INFO,
                                                &manifest_files[1])) {
        goto out;
    }

    // Make sure we have at least one layer, if not, go ahead and return
    if (manifest_files[0].count == 0 && manifest_files[1].count == 0) {
        goto out;
    }

    // cleanup any previously scanned libraries
    loader_delete_layer_properties(inst, instance_layers);

    loader_platform_thread_lock_mutex(&loader_json_lock);
    lockedMutex = true;
    for (implicit = 0; implicit < 2; implicit++) {
        for (uint32_t i = 0; i < manifest_files[implicit].count; i++) {
            file_str = manifest_files[implicit].filename_list[i];
            if (file_str == NULL) continue;

            // parse file into JSON struct
            VkResult res = loader_get_json(inst, file_str, &json);
            if (VK_ERROR_OUT_OF_HOST_MEMORY == res) {
                break;
            } else if (VK_SUCCESS != res || NULL == json) {
                continue;
            }

            loader_add_layer_properties(inst, instance_layers, json, (implicit == 1), file_str);
            cJSON_Delete(json);
        }
    }

    // add a meta layer for validation if the validation layers are all present
    loader_add_layer_property_meta(inst, sizeof(std_validation_names) / sizeof(std_validation_names[0]), std_validation_names,
                                   instance_layers);

out:

    for (uint32_t manFile = 0; manFile < 2; manFile++) {
        if (NULL != manifest_files[manFile].filename_list) {
            for (uint32_t i = 0; i < manifest_files[manFile].count; i++) {
                if (NULL != manifest_files[manFile].filename_list[i]) {
                    loader_instance_heap_free(inst, manifest_files[manFile].filename_list[i]);
                }
            }
            loader_instance_heap_free(inst, manifest_files[manFile].filename_list);
        }
    }
    if (lockedMutex) {
        loader_platform_thread_unlock_mutex(&loader_json_lock);
    }
}

void loader_implicit_layer_scan(const struct loader_instance *inst, struct loader_layer_list *instance_layers) {
    char *file_str;
    struct loader_manifest_files manifest_files;
    cJSON *json;
    uint32_t i;

    // Pass NULL for environment variable override - implicit layers are not
    // overridden by LAYERS_PATH_ENV
    VkResult res =
        loader_get_manifest_files(inst, NULL, NULL, true, false, DEFAULT_VK_ILAYERS_INFO, RELATIVE_VK_ILAYERS_INFO, &manifest_files);
    if (VK_SUCCESS != res || manifest_files.count == 0) {
        return;
    }

    /* cleanup any previously scanned libraries */
    loader_delete_layer_properties(inst, instance_layers);

    loader_platform_thread_lock_mutex(&loader_json_lock);

    for (i = 0; i < manifest_files.count; i++) {
        file_str = manifest_files.filename_list[i];
        if (file_str == NULL) {
            continue;
        }

        // parse file into JSON struct
        res = loader_get_json(inst, file_str, &json);
        if (VK_ERROR_OUT_OF_HOST_MEMORY == res) {
            break;
        } else if (VK_SUCCESS != res || NULL == json) {
            continue;
        }

        loader_add_layer_properties(inst, instance_layers, json, true, file_str);

        loader_instance_heap_free(inst, file_str);
        cJSON_Delete(json);
    }
    loader_instance_heap_free(inst, manifest_files.filename_list);

    // add a meta layer for validation if the validation layers are all present
    loader_add_layer_property_meta(inst, sizeof(std_validation_names) / sizeof(std_validation_names[0]), std_validation_names,
                                   instance_layers);

    loader_platform_thread_unlock_mutex(&loader_json_lock);
}

static VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL loader_gpdpa_instance_internal(VkInstance inst, const char *pName) {
    // inst is not wrapped
    if (inst == VK_NULL_HANDLE) {
        return NULL;
    }
    VkLayerInstanceDispatchTable *disp_table = *(VkLayerInstanceDispatchTable **)inst;
    void *addr;

    if (disp_table == NULL) return NULL;

    bool found_name;
    addr = loader_lookup_instance_dispatch_table(disp_table, pName, &found_name);
    if (found_name) {
        return addr;
    }

    if (loader_phys_dev_ext_gpa(loader_get_instance(inst), pName, true, NULL, &addr)) return addr;

    // Don't call down the chain, this would be an infinite loop
    loader_log(NULL, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0, "loader_gpdpa_instance_internal() unrecognized name %s", pName);
    return NULL;
}

static VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL loader_gpdpa_instance_terminator(VkInstance inst, const char *pName) {
    // inst is not wrapped
    if (inst == VK_NULL_HANDLE) {
        return NULL;
    }
    VkLayerInstanceDispatchTable *disp_table = *(VkLayerInstanceDispatchTable **)inst;
    void *addr;

    if (disp_table == NULL) return NULL;

    bool found_name;
    addr = loader_lookup_instance_dispatch_table(disp_table, pName, &found_name);
    if (found_name) {
        return addr;
    }

    // Get the terminator, but don't perform checking since it should already
    // have been setup if we get here.
    if (loader_phys_dev_ext_gpa(loader_get_instance(inst), pName, false, NULL, &addr)) {
        return addr;
    }

    // Don't call down the chain, this would be an infinite loop
    loader_log(NULL, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0, "loader_gpdpa_instance_terminator() unrecognized name %s", pName);
    return NULL;
}

static VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL loader_gpa_instance_internal(VkInstance inst, const char *pName) {
    if (!strcmp(pName, "vkGetInstanceProcAddr")) {
        return (PFN_vkVoidFunction)loader_gpa_instance_internal;
    }
    if (!strcmp(pName, "vk_layerGetPhysicalDeviceProcAddr")) {
        return (PFN_vkVoidFunction)loader_gpdpa_instance_terminator;
    }
    if (!strcmp(pName, "vkCreateInstance")) {
        return (PFN_vkVoidFunction)terminator_CreateInstance;
    }
    if (!strcmp(pName, "vkCreateDevice")) {
        return (PFN_vkVoidFunction)terminator_CreateDevice;
    }

    // inst is not wrapped
    if (inst == VK_NULL_HANDLE) {
        return NULL;
    }
    VkLayerInstanceDispatchTable *disp_table = *(VkLayerInstanceDispatchTable **)inst;
    void *addr;

    if (disp_table == NULL) return NULL;

    bool found_name;
    addr = loader_lookup_instance_dispatch_table(disp_table, pName, &found_name);
    if (found_name) {
        return addr;
    }

    // Don't call down the chain, this would be an infinite loop
    loader_log(NULL, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0, "loader_gpa_instance_internal() unrecognized name %s", pName);
    return NULL;
}

VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL loader_gpa_device_internal(VkDevice device, const char *pName) {
    struct loader_device *dev;
    struct loader_icd_term *icd_term = loader_get_icd_and_device(device, &dev, NULL);

    // NOTE: Device Funcs needing Trampoline/Terminator.
    // Overrides for device functions needing a trampoline and
    // a terminator because certain device entry-points still need to go
    // through a terminator before hitting the ICD.  This could be for
    // several reasons, but the main one is currently unwrapping an
    // object before passing the appropriate info along to the ICD.
    // This is why we also have to override the direct ICD call to
    // vkGetDeviceProcAddr to intercept those calls.
    if (!strcmp(pName, "vkGetDeviceProcAddr")) {
        return (PFN_vkVoidFunction)loader_gpa_device_internal;
    } else if (!strcmp(pName, "vkCreateSwapchainKHR")) {
        return (PFN_vkVoidFunction)terminator_vkCreateSwapchainKHR;
    } else if (!strcmp(pName, "vkCreateSharedSwapchainsKHR")) {
        return (PFN_vkVoidFunction)terminator_vkCreateSharedSwapchainsKHR;
    } else if (!strcmp(pName, "vkDebugMarkerSetObjectTagEXT")) {
        return (PFN_vkVoidFunction)terminator_DebugMarkerSetObjectTagEXT;
    } else if (!strcmp(pName, "vkDebugMarkerSetObjectNameEXT")) {
        return (PFN_vkVoidFunction)terminator_DebugMarkerSetObjectNameEXT;
    }

    return icd_term->GetDeviceProcAddr(device, pName);
}

/**
 * Initialize device_ext dispatch table entry as follows:
 * If dev == NULL find all logical devices created within this instance and
 *  init the entry (given by idx) in the ext dispatch table.
 * If dev != NULL only initialize the entry in the given dev's dispatch table.
 * The initialization value is gotten by calling down the device chain with
 * GDPA.
 * If GDPA returns NULL then don't initialize the dispatch table entry.
 */
static void loader_init_dispatch_dev_ext_entry(struct loader_instance *inst, struct loader_device *dev, uint32_t idx,
                                               const char *funcName)

{
    void *gdpa_value;
    if (dev != NULL) {
        gdpa_value = dev->loader_dispatch.core_dispatch.GetDeviceProcAddr(dev->chain_device, funcName);
        if (gdpa_value != NULL) dev->loader_dispatch.ext_dispatch.dev_ext[idx] = (PFN_vkDevExt)gdpa_value;
    } else {
        for (struct loader_icd_term *icd_term = inst->icd_terms; icd_term != NULL; icd_term = icd_term->next) {
            struct loader_device *ldev = icd_term->logical_device_list;
            while (ldev) {
                gdpa_value = ldev->loader_dispatch.core_dispatch.GetDeviceProcAddr(ldev->chain_device, funcName);
                if (gdpa_value != NULL) ldev->loader_dispatch.ext_dispatch.dev_ext[idx] = (PFN_vkDevExt)gdpa_value;
                ldev = ldev->next;
            }
        }
    }
}

/**
 * Find all dev extension in the hash table  and initialize the dispatch table
 * for dev  for each of those extension entrypoints found in hash table.

 */
void loader_init_dispatch_dev_ext(struct loader_instance *inst, struct loader_device *dev) {
    for (uint32_t i = 0; i < MAX_NUM_UNKNOWN_EXTS; i++) {
        if (inst->dev_ext_disp_hash[i].func_name != NULL)
            loader_init_dispatch_dev_ext_entry(inst, dev, i, inst->dev_ext_disp_hash[i].func_name);
    }
}

static bool loader_check_icds_for_dev_ext_address(struct loader_instance *inst, const char *funcName) {
    struct loader_icd_term *icd_term;
    icd_term = inst->icd_terms;
    while (NULL != icd_term) {
        if (icd_term->scanned_icd->GetInstanceProcAddr(icd_term->instance, funcName))
            // this icd supports funcName
            return true;
        icd_term = icd_term->next;
    }

    return false;
}

static bool loader_check_layer_list_for_dev_ext_address(const struct loader_layer_list *const layers, const char *funcName) {
    // Iterate over the layers.
    for (uint32_t layer = 0; layer < layers->count; ++layer) {
        // Iterate over the extensions.
        const struct loader_device_extension_list *const extensions = &(layers->list[layer].device_extension_list);
        for (uint32_t extension = 0; extension < extensions->count; ++extension) {
            // Iterate over the entry points.
            const struct loader_dev_ext_props *const property = &(extensions->list[extension]);
            for (uint32_t entry = 0; entry < property->entrypoint_count; ++entry) {
                if (strcmp(property->entrypoints[entry], funcName) == 0) {
                    return true;
                }
            }
        }
    }

    return false;
}

static void loader_free_dev_ext_table(struct loader_instance *inst) {
    for (uint32_t i = 0; i < MAX_NUM_UNKNOWN_EXTS; i++) {
        loader_instance_heap_free(inst, inst->dev_ext_disp_hash[i].func_name);
        loader_instance_heap_free(inst, inst->dev_ext_disp_hash[i].list.index);
    }
    memset(inst->dev_ext_disp_hash, 0, sizeof(inst->dev_ext_disp_hash));
}

static bool loader_add_dev_ext_table(struct loader_instance *inst, uint32_t *ptr_idx, const char *funcName) {
    uint32_t i;
    uint32_t idx = *ptr_idx;
    struct loader_dispatch_hash_list *list = &inst->dev_ext_disp_hash[idx].list;

    if (!inst->dev_ext_disp_hash[idx].func_name) {
        // no entry here at this idx, so use it
        assert(list->capacity == 0);
        inst->dev_ext_disp_hash[idx].func_name =
            (char *)loader_instance_heap_alloc(inst, strlen(funcName) + 1, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (inst->dev_ext_disp_hash[idx].func_name == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_add_dev_ext_table: Failed to allocate memory "
                       "for func_name %s",
                       funcName);
            return false;
        }
        strncpy(inst->dev_ext_disp_hash[idx].func_name, funcName, strlen(funcName) + 1);
        return true;
    }

    // check for enough capacity
    if (list->capacity == 0) {
        list->index = loader_instance_heap_alloc(inst, 8 * sizeof(*(list->index)), VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (list->index == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_add_dev_ext_table: Failed to allocate memory "
                       "for list index",
                       funcName);
            return false;
        }
        list->capacity = 8 * sizeof(*(list->index));
    } else if (list->capacity < (list->count + 1) * sizeof(*(list->index))) {
        list->index = loader_instance_heap_realloc(inst, list->index, list->capacity, list->capacity * 2,
                                                   VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (list->index == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_add_dev_ext_table: Failed to reallocate memory "
                       "for list index",
                       funcName);
            return false;
        }
        list->capacity *= 2;
    }

    // find an unused index in the hash table and use it
    i = (idx + 1) % MAX_NUM_UNKNOWN_EXTS;
    do {
        if (!inst->dev_ext_disp_hash[i].func_name) {
            assert(inst->dev_ext_disp_hash[i].list.capacity == 0);
            inst->dev_ext_disp_hash[i].func_name =
                (char *)loader_instance_heap_alloc(inst, strlen(funcName) + 1, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
            if (inst->dev_ext_disp_hash[i].func_name == NULL) {
                loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                           "loader_add_dev_ext_table: Failed to allocate memory "
                           "for func_name %s",
                           funcName);
                return false;
            }
            strncpy(inst->dev_ext_disp_hash[i].func_name, funcName, strlen(funcName) + 1);
            list->index[list->count] = i;
            list->count++;
            *ptr_idx = i;
            return true;
        }
        i = (i + 1) % MAX_NUM_UNKNOWN_EXTS;
    } while (i != idx);

    loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
               "loader_add_dev_ext_table:  Could not insert into hash table; is "
               "it full?");

    return false;
}

static bool loader_name_in_dev_ext_table(struct loader_instance *inst, uint32_t *idx, const char *funcName) {
    uint32_t alt_idx;
    if (inst->dev_ext_disp_hash[*idx].func_name && !strcmp(inst->dev_ext_disp_hash[*idx].func_name, funcName)) return true;

    // funcName wasn't at the primary spot in the hash table
    // search the list of secondary locations (shallow search, not deep search)
    for (uint32_t i = 0; i < inst->dev_ext_disp_hash[*idx].list.count; i++) {
        alt_idx = inst->dev_ext_disp_hash[*idx].list.index[i];
        if (!strcmp(inst->dev_ext_disp_hash[*idx].func_name, funcName)) {
            *idx = alt_idx;
            return true;
        }
    }

    return false;
}

/**
 * This function returns generic trampoline code address for unknown entry
 * points.
 * Presumably, these unknown entry points (as given by funcName) are device
 * extension entrypoints.  A hash table is used to keep a list of unknown entry
 * points and their mapping to the device extension dispatch table
 * (struct loader_dev_ext_dispatch_table).
 * \returns
 * For a given entry point string (funcName), if an existing mapping is found
 * the
 * trampoline address for that mapping is returned. Otherwise, this unknown
 * entry point
 * has not been seen yet. Next check if a layer or ICD supports it.  If so then
 * a
 * new entry in the hash table is initialized and that trampoline address for
 * the new entry is returned. Null is returned if the hash table is full or
 * if no discovered layer or ICD returns a non-NULL GetProcAddr for it.
 */
void *loader_dev_ext_gpa(struct loader_instance *inst, const char *funcName) {
    uint32_t idx;
    uint32_t seed = 0;

    idx = murmurhash(funcName, strlen(funcName), seed) % MAX_NUM_UNKNOWN_EXTS;

    if (loader_name_in_dev_ext_table(inst, &idx, funcName))
        // found funcName already in hash
        return loader_get_dev_ext_trampoline(idx);

    // Check if funcName is supported in either ICDs or a layer library
    if (!loader_check_icds_for_dev_ext_address(inst, funcName) &&
        !loader_check_layer_list_for_dev_ext_address(&inst->instance_layer_list, funcName)) {
        // if support found in layers continue on
        return NULL;
    }

    if (loader_add_dev_ext_table(inst, &idx, funcName)) {
        // successfully added new table entry
        // init any dev dispatch table entrys as needed
        loader_init_dispatch_dev_ext_entry(inst, NULL, idx, funcName);
        return loader_get_dev_ext_trampoline(idx);
    }

    return NULL;
}

static bool loader_check_icds_for_phys_dev_ext_address(struct loader_instance *inst, const char *funcName) {
    struct loader_icd_term *icd_term;
    icd_term = inst->icd_terms;
    while (NULL != icd_term) {
        if (icd_term->scanned_icd->interface_version >= MIN_PHYS_DEV_EXTENSION_ICD_INTERFACE_VERSION &&
            icd_term->scanned_icd->GetPhysicalDeviceProcAddr(icd_term->instance, funcName))
            // this icd supports funcName
            return true;
        icd_term = icd_term->next;
    }

    return false;
}

static bool loader_check_layer_list_for_phys_dev_ext_address(struct loader_instance *inst, const char *funcName) {
    struct loader_layer_properties *layer_prop_list = inst->activated_layer_list.list;
    for (uint32_t layer = 0; layer < inst->activated_layer_list.count; ++layer) {
        // If this layer supports the vk_layerGetPhysicalDeviceProcAddr, then call
        // it and see if it returns a valid pointer for this function name.
        if (layer_prop_list[layer].interface_version > 1) {
            const struct loader_layer_functions *const functions = &(layer_prop_list[layer].functions);
            if (NULL != functions->get_physical_device_proc_addr &&
                NULL != functions->get_physical_device_proc_addr((VkInstance)inst, funcName)) {
                return true;
            }
        }
    }

    return false;
}

static void loader_free_phys_dev_ext_table(struct loader_instance *inst) {
    for (uint32_t i = 0; i < MAX_NUM_UNKNOWN_EXTS; i++) {
        loader_instance_heap_free(inst, inst->phys_dev_ext_disp_hash[i].func_name);
        loader_instance_heap_free(inst, inst->phys_dev_ext_disp_hash[i].list.index);
    }
    memset(inst->phys_dev_ext_disp_hash, 0, sizeof(inst->phys_dev_ext_disp_hash));
}

static bool loader_add_phys_dev_ext_table(struct loader_instance *inst, uint32_t *ptr_idx, const char *funcName) {
    uint32_t i;
    uint32_t idx = *ptr_idx;
    struct loader_dispatch_hash_list *list = &inst->phys_dev_ext_disp_hash[idx].list;

    if (!inst->phys_dev_ext_disp_hash[idx].func_name) {
        // no entry here at this idx, so use it
        assert(list->capacity == 0);
        inst->phys_dev_ext_disp_hash[idx].func_name =
            (char *)loader_instance_heap_alloc(inst, strlen(funcName) + 1, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (inst->phys_dev_ext_disp_hash[idx].func_name == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_add_phys_dev_ext_table() can't allocate memory for "
                       "func_name");
            return false;
        }
        strncpy(inst->phys_dev_ext_disp_hash[idx].func_name, funcName, strlen(funcName) + 1);
        return true;
    }

    // check for enough capacity
    if (list->capacity == 0) {
        list->index = loader_instance_heap_alloc(inst, 8 * sizeof(*(list->index)), VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (list->index == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0, "loader_add_phys_dev_ext_table() can't allocate list memory");
            return false;
        }
        list->capacity = 8 * sizeof(*(list->index));
    } else if (list->capacity < (list->count + 1) * sizeof(*(list->index))) {
        list->index = loader_instance_heap_realloc(inst, list->index, list->capacity, list->capacity * 2,
                                                   VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
        if (list->index == NULL) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0, "loader_add_phys_dev_ext_table() can't reallocate list memory");
            return false;
        }
        list->capacity *= 2;
    }

    // find an unused index in the hash table and use it
    i = (idx + 1) % MAX_NUM_UNKNOWN_EXTS;
    do {
        if (!inst->phys_dev_ext_disp_hash[i].func_name) {
            assert(inst->phys_dev_ext_disp_hash[i].list.capacity == 0);
            inst->phys_dev_ext_disp_hash[i].func_name =
                (char *)loader_instance_heap_alloc(inst, strlen(funcName) + 1, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
            if (inst->phys_dev_ext_disp_hash[i].func_name == NULL) {
                loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                           "loader_add_dev_ext_table() can't rallocate "
                           "func_name memory");
                return false;
            }
            strncpy(inst->phys_dev_ext_disp_hash[i].func_name, funcName, strlen(funcName) + 1);
            list->index[list->count] = i;
            list->count++;
            *ptr_idx = i;
            return true;
        }
        i = (i + 1) % MAX_NUM_UNKNOWN_EXTS;
    } while (i != idx);

    loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
               "loader_add_phys_dev_ext_table() couldn't insert into hash table; is "
               "it full?");
    return false;
}

static bool loader_name_in_phys_dev_ext_table(struct loader_instance *inst, uint32_t *idx, const char *funcName) {
    uint32_t alt_idx;
    if (inst->phys_dev_ext_disp_hash[*idx].func_name && !strcmp(inst->phys_dev_ext_disp_hash[*idx].func_name, funcName))
        return true;

    // funcName wasn't at the primary spot in the hash table
    // search the list of secondary locations (shallow search, not deep search)
    for (uint32_t i = 0; i < inst->phys_dev_ext_disp_hash[*idx].list.count; i++) {
        alt_idx = inst->phys_dev_ext_disp_hash[*idx].list.index[i];
        if (!strcmp(inst->phys_dev_ext_disp_hash[*idx].func_name, funcName)) {
            *idx = alt_idx;
            return true;
        }
    }

    return false;
}

// This function returns a generic trampoline and/or terminator function
// address for any unknown physical device extension commands.  A hash
// table is used to keep a list of unknown entry points and their
// mapping to the physical device extension dispatch table (struct
// loader_phys_dev_ext_dispatch_table).
// For a given entry point string (funcName), if an existing mapping is
// found, then the trampoline address for that mapping is returned in
// tramp_addr (if it is not NULL) and the terminator address for that
// mapping is returned in term_addr (if it is not NULL). Otherwise,
// this unknown entry point has not been seen yet.
// If it has not been seen before, and perform_checking is 'true',
// check if a layer or and ICD supports it.  If so then a new entry in
// the hash table is initialized and the trampoline and/or terminator
// addresses are returned.
// Null is returned if the hash table is full or if no discovered layer or
// ICD returns a non-NULL GetProcAddr for it.
bool loader_phys_dev_ext_gpa(struct loader_instance *inst, const char *funcName, bool perform_checking, void **tramp_addr,
                             void **term_addr) {
    uint32_t idx;
    uint32_t seed = 0;
    bool success = false;

    if (inst == NULL) {
        goto out;
    }

    if (NULL != tramp_addr) {
        *tramp_addr = NULL;
    }
    if (NULL != term_addr) {
        *term_addr = NULL;
    }

    // We should always check to see if any ICD supports it.
    if (!loader_check_icds_for_phys_dev_ext_address(inst, funcName)) {
        // If we're not checking layers, or we are and it's not in a layer, just
        // return
        if (!perform_checking || !loader_check_layer_list_for_phys_dev_ext_address(inst, funcName)) {
            goto out;
        }
    }

    idx = murmurhash(funcName, strlen(funcName), seed) % MAX_NUM_UNKNOWN_EXTS;
    if (perform_checking && !loader_name_in_phys_dev_ext_table(inst, &idx, funcName)) {
        uint32_t i;
        bool added = false;

        // Only need to add first one to get index in Instance.  Others will use
        // the same index.
        if (!added && loader_add_phys_dev_ext_table(inst, &idx, funcName)) {
            added = true;
        }

        // Setup the ICD function pointers
        struct loader_icd_term *icd_term = inst->icd_terms;
        while (NULL != icd_term) {
            if (MIN_PHYS_DEV_EXTENSION_ICD_INTERFACE_VERSION <= icd_term->scanned_icd->interface_version &&
                NULL != icd_term->scanned_icd->GetPhysicalDeviceProcAddr) {
                icd_term->phys_dev_ext[idx] =
                    (PFN_PhysDevExt)icd_term->scanned_icd->GetPhysicalDeviceProcAddr(icd_term->instance, funcName);

                // Make sure we set the instance dispatch to point to the
                // loader's terminator now since we can at least handle it
                // in one ICD.
                inst->disp->phys_dev_ext[idx] = loader_get_phys_dev_ext_termin(idx);
            } else {
                icd_term->phys_dev_ext[idx] = NULL;
            }

            icd_term = icd_term->next;
        }

        // Now, search for the first layer attached and query using it to get
        // the first entry point.
        for (i = 0; i < inst->activated_layer_list.count; i++) {
            struct loader_layer_properties *layer_prop = &inst->activated_layer_list.list[i];
            if (layer_prop->interface_version > 1 && NULL != layer_prop->functions.get_physical_device_proc_addr) {
                inst->disp->phys_dev_ext[idx] =
                    (PFN_PhysDevExt)layer_prop->functions.get_physical_device_proc_addr((VkInstance)inst, funcName);
                if (NULL != inst->disp->phys_dev_ext[idx]) {
                    break;
                }
            }
        }
    }

    if (NULL != tramp_addr) {
        *tramp_addr = loader_get_phys_dev_ext_tramp(idx);
    }

    if (NULL != term_addr) {
        *term_addr = loader_get_phys_dev_ext_termin(idx);
    }

    success = true;

out:
    return success;
}

struct loader_instance *loader_get_instance(const VkInstance instance) {
    /* look up the loader_instance in our list by comparing dispatch tables, as
     * there is no guarantee the instance is still a loader_instance* after any
     * layers which wrap the instance object.
     */
    const VkLayerInstanceDispatchTable *disp;
    struct loader_instance *ptr_instance = NULL;
    disp = loader_get_instance_layer_dispatch(instance);
    for (struct loader_instance *inst = loader.instances; inst; inst = inst->next) {
        if (&inst->disp->layer_inst_disp == disp) {
            ptr_instance = inst;
            break;
        }
    }
    return ptr_instance;
}

static loader_platform_dl_handle loader_open_layer_lib(const struct loader_instance *inst, const char *chain_type,
                                                       struct loader_layer_properties *prop) {
    if ((prop->lib_handle = loader_platform_open_library(prop->lib_name)) == NULL) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0, "loader_open_layer_lib: Failed to open library %s", prop->lib_name);
    } else {
        loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Loading layer library %s", prop->lib_name);
    }

    return prop->lib_handle;
}

static void loader_close_layer_lib(const struct loader_instance *inst, struct loader_layer_properties *prop) {
    if (prop->lib_handle) {
        loader_platform_close_library(prop->lib_handle);
        loader_log(inst, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Unloading layer library %s", prop->lib_name);
        prop->lib_handle = NULL;
    }
}

void loader_deactivate_layers(const struct loader_instance *instance, struct loader_device *device,
                              struct loader_layer_list *list) {
    /* delete instance list of enabled layers and close any layer libraries */
    for (uint32_t i = 0; i < list->count; i++) {
        struct loader_layer_properties *layer_prop = &list->list[i];

        loader_close_layer_lib(instance, layer_prop);
    }
    loader_destroy_layer_list(instance, device, list);
}

/**
 * Go through the search_list and find any layers which match type. If layer
 * type match is found in then add it to ext_list.
 */
static void loader_add_layer_implicit(const struct loader_instance *inst, const enum layer_type type,
                                      struct loader_layer_list *list, const struct loader_layer_list *search_list) {
    bool enable;
    char *env_value;
    uint32_t i;
    for (i = 0; i < search_list->count; i++) {
        const struct loader_layer_properties *prop = &search_list->list[i];
        if (prop->type & type) {
            /* Found an implicit layer, see if it should be enabled */
            enable = false;

            // if no enable_environment variable is specified, this implicit
            // layer
            // should always be enabled. Otherwise check if the variable is set
            if (prop->enable_env_var.name[0] == 0) {
                enable = true;
            } else {
                env_value = loader_getenv(prop->enable_env_var.name, inst);
                if (env_value && !strcmp(prop->enable_env_var.value, env_value)) enable = true;
                loader_free_getenv(env_value, inst);
            }

            // disable_environment has priority, i.e. if both enable and disable
            // environment variables are set, the layer is disabled. Implicit
            // layers
            // are required to have a disable_environment variables
            env_value = loader_getenv(prop->disable_env_var.name, inst);
            if (env_value) {
                enable = false;
            }
            loader_free_getenv(env_value, inst);

            if (enable) {
                loader_add_to_layer_list(inst, list, 1, prop);
            }
        }
    }
}

/**
 * Get the layer name(s) from the env_name environment variable. If layer
 * is found in search_list then add it to layer_list.  But only add it to
 * layer_list if type matches.
 */
static void loader_add_layer_env(struct loader_instance *inst, const enum layer_type type, const char *env_name,
                                 struct loader_layer_list *layer_list, const struct loader_layer_list *search_list) {
    char *layerEnv;
    char *next, *name;

    layerEnv = loader_getenv(env_name, inst);
    if (layerEnv == NULL) {
        return;
    }
    name = loader_stack_alloc(strlen(layerEnv) + 1);
    if (name == NULL) {
        return;
    }
    strcpy(name, layerEnv);

    loader_free_getenv(layerEnv, inst);

    while (name && *name) {
        next = loader_get_next_path(name);
        if (!strcmp(std_validation_str, name)) {
            /* add meta list of layers
               don't attempt to remove duplicate layers already added by app or
               env var
             */
            loader_log(inst, VK_DEBUG_REPORT_INFORMATION_BIT_EXT, 0, "Expanding meta layer %s found in environment variable",
                       std_validation_str);
            if (type == VK_LAYER_TYPE_INSTANCE_EXPLICIT) inst->activated_layers_are_std_val = true;
            for (uint32_t i = 0; i < sizeof(std_validation_names) / sizeof(std_validation_names[0]); i++) {
                loader_find_layer_name_add_list(inst, std_validation_names[i], type, search_list, layer_list);
            }
        } else {
            loader_find_layer_name_add_list(inst, name, type, search_list, layer_list);
        }
        name = next;
    }

    return;
}

VkResult loader_enable_instance_layers(struct loader_instance *inst, const VkInstanceCreateInfo *pCreateInfo,
                                       const struct loader_layer_list *instance_layers) {
    VkResult err;

    assert(inst && "Cannot have null instance");

    if (!loader_init_layer_list(inst, &inst->activated_layer_list)) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_enable_instance_layers: Failed to initialize"
                   " the layer list");
        return VK_ERROR_OUT_OF_HOST_MEMORY;
    }

    /* Add any implicit layers first */
    loader_add_layer_implicit(inst, VK_LAYER_TYPE_INSTANCE_IMPLICIT, &inst->activated_layer_list, instance_layers);

    /* Add any layers specified via environment variable next */
    loader_add_layer_env(inst, VK_LAYER_TYPE_INSTANCE_EXPLICIT, "VK_INSTANCE_LAYERS", &inst->activated_layer_list, instance_layers);

    /* Add layers specified by the application */
    err = loader_add_layer_names_to_list(inst, &inst->activated_layer_list, pCreateInfo->enabledLayerCount,
                                         pCreateInfo->ppEnabledLayerNames, instance_layers);

    return err;
}

// Determine the layer interface version to use.
bool loader_get_layer_interface_version(PFN_vkNegotiateLoaderLayerInterfaceVersion fp_negotiate_layer_version,
                                        VkNegotiateLayerInterface *interface_struct) {
    memset(interface_struct, 0, sizeof(VkNegotiateLayerInterface));

    // Base assumption is that all layers are version 1 at least.
    interface_struct->loaderLayerInterfaceVersion = 1;

    if (fp_negotiate_layer_version != NULL) {
        // Layer supports the negotiation API, so call it with the loader's
        // latest version supported
        interface_struct->loaderLayerInterfaceVersion = CURRENT_LOADER_LAYER_INTERFACE_VERSION;
        VkResult result = fp_negotiate_layer_version(interface_struct);

        if (result != VK_SUCCESS) {
            // Layer no longer supports the loader's latest interface version so
            // fail loading the Layer
            return false;
        }
    }

    if (interface_struct->loaderLayerInterfaceVersion < MIN_SUPPORTED_LOADER_LAYER_INTERFACE_VERSION) {
        // Loader no longer supports the layer's latest interface version so
        // fail loading the layer
        return false;
    }

    return true;
}

/*
 * Given the list of layers to activate in the loader_instance
 * structure. This function will add a VkLayerInstanceCreateInfo
 * structure to the VkInstanceCreateInfo.pNext pointer.
 * Each activated layer will have it's own VkLayerInstanceLink
 * structure that tells the layer what Get*ProcAddr to call to
 * get function pointers to the next layer down.
 * Once the chain info has been created this function will
 * execute the CreateInstance call chain. Each layer will
 * then have an opportunity in it's CreateInstance function
 * to setup it's dispatch table when the lower layer returns
 * successfully.
 * Each layer can wrap or not-wrap the returned VkInstance object
 * as it sees fit.
 * The instance chain is terminated by a loader function
 * that will call CreateInstance on all available ICD's and
 * cache those VkInstance objects for future use.
 */
VkResult loader_create_instance_chain(const VkInstanceCreateInfo *pCreateInfo, const VkAllocationCallbacks *pAllocator,
                                      struct loader_instance *inst, VkInstance *created_instance) {
    uint32_t activated_layers = 0;
    VkLayerInstanceCreateInfo chain_info;
    VkLayerInstanceLink *layer_instance_link_info = NULL;
    VkInstanceCreateInfo loader_create_info;
    VkResult res;

    PFN_vkGetInstanceProcAddr next_gipa = loader_gpa_instance_internal;
    PFN_vkGetInstanceProcAddr cur_gipa = loader_gpa_instance_internal;
    PFN_GetPhysicalDeviceProcAddr next_gpdpa = loader_gpdpa_instance_internal;
    PFN_GetPhysicalDeviceProcAddr cur_gpdpa = loader_gpdpa_instance_internal;

    memcpy(&loader_create_info, pCreateInfo, sizeof(VkInstanceCreateInfo));

    if (inst->activated_layer_list.count > 0) {
        chain_info.u.pLayerInfo = NULL;
        chain_info.pNext = pCreateInfo->pNext;
        chain_info.sType = VK_STRUCTURE_TYPE_LOADER_INSTANCE_CREATE_INFO;
        chain_info.function = VK_LAYER_LINK_INFO;
        loader_create_info.pNext = &chain_info;

        layer_instance_link_info = loader_stack_alloc(sizeof(VkLayerInstanceLink) * inst->activated_layer_list.count);
        if (!layer_instance_link_info) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_create_instance_chain: Failed to alloc Instance"
                       " objects for layer");
            return VK_ERROR_OUT_OF_HOST_MEMORY;
        }

        // Create instance chain of enabled layers
        for (int32_t i = inst->activated_layer_list.count - 1; i >= 0; i--) {
            struct loader_layer_properties *layer_prop = &inst->activated_layer_list.list[i];
            loader_platform_dl_handle lib_handle;

            lib_handle = loader_open_layer_lib(inst, "instance", layer_prop);
            if (!lib_handle) {
                continue;
            }

            if (NULL == layer_prop->functions.negotiate_layer_interface) {
                PFN_vkNegotiateLoaderLayerInterfaceVersion negotiate_interface = NULL;
                bool functions_in_interface = false;
                if (strlen(layer_prop->functions.str_negotiate_interface) == 0) {
                    negotiate_interface = (PFN_vkNegotiateLoaderLayerInterfaceVersion)loader_platform_get_proc_address(
                        lib_handle, "vkNegotiateLoaderLayerInterfaceVersion");
                } else {
                    negotiate_interface = (PFN_vkNegotiateLoaderLayerInterfaceVersion)loader_platform_get_proc_address(
                        lib_handle, layer_prop->functions.str_negotiate_interface);
                }

                // If we can negotiate an interface version, then we can also
                // get everything we need from the one function call, so try
                // that first, and see if we can get all the function pointers
                // necessary from that one call.
                if (NULL != negotiate_interface) {
                    layer_prop->functions.negotiate_layer_interface = negotiate_interface;

                    VkNegotiateLayerInterface interface_struct;

                    if (loader_get_layer_interface_version(negotiate_interface, &interface_struct)) {
                        // Go ahead and set the properites version to the
                        // correct value.
                        layer_prop->interface_version = interface_struct.loaderLayerInterfaceVersion;

                        // If the interface is 2 or newer, we have access to the
                        // new GetPhysicalDeviceProcAddr function, so grab it,
                        // and the other necessary functions, from the
                        // structure.
                        if (interface_struct.loaderLayerInterfaceVersion > 1) {
                            cur_gipa = interface_struct.pfnGetInstanceProcAddr;
                            cur_gpdpa = interface_struct.pfnGetPhysicalDeviceProcAddr;
                            if (cur_gipa != NULL) {
                                // We've set the functions, so make sure we
                                // don't do the unnecessary calls later.
                                functions_in_interface = true;
                            }
                        }
                    }
                }

                if (!functions_in_interface) {
                    if ((cur_gipa = layer_prop->functions.get_instance_proc_addr) == NULL) {
                        if (strlen(layer_prop->functions.str_gipa) == 0) {
                            cur_gipa =
                                (PFN_vkGetInstanceProcAddr)loader_platform_get_proc_address(lib_handle, "vkGetInstanceProcAddr");
                            layer_prop->functions.get_instance_proc_addr = cur_gipa;
                        } else {
                            cur_gipa = (PFN_vkGetInstanceProcAddr)loader_platform_get_proc_address(lib_handle,
                                                                                                   layer_prop->functions.str_gipa);
                        }

                        if (NULL == cur_gipa) {
                            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                                       "loader_create_instance_chain: Failed to"
                                       " find \'vkGetInstanceProcAddr\' in "
                                       "layer %s",
                                       layer_prop->lib_name);
                            continue;
                        }
                    }
                }
            }

            layer_instance_link_info[activated_layers].pNext = chain_info.u.pLayerInfo;
            layer_instance_link_info[activated_layers].pfnNextGetInstanceProcAddr = next_gipa;
            layer_instance_link_info[activated_layers].pfnNextGetPhysicalDeviceProcAddr = next_gpdpa;
            next_gipa = cur_gipa;
            if (layer_prop->interface_version > 1 && cur_gpdpa != NULL) {
                layer_prop->functions.get_physical_device_proc_addr = cur_gpdpa;
                next_gpdpa = cur_gpdpa;
            }

            chain_info.u.pLayerInfo = &layer_instance_link_info[activated_layers];

            loader_log(inst, VK_DEBUG_REPORT_INFORMATION_BIT_EXT, 0, "Insert instance layer %s (%s)", layer_prop->info.layerName,
                       layer_prop->lib_name);

            activated_layers++;
        }
    }

    PFN_vkCreateInstance fpCreateInstance = (PFN_vkCreateInstance)next_gipa(*created_instance, "vkCreateInstance");
    if (fpCreateInstance) {
        VkLayerInstanceCreateInfo create_info_disp;

        create_info_disp.sType = VK_STRUCTURE_TYPE_LOADER_INSTANCE_CREATE_INFO;
        create_info_disp.function = VK_LOADER_DATA_CALLBACK;

        create_info_disp.u.pfnSetInstanceLoaderData = vkSetInstanceDispatch;

        create_info_disp.pNext = loader_create_info.pNext;
        loader_create_info.pNext = &create_info_disp;
        res = fpCreateInstance(&loader_create_info, pAllocator, created_instance);
    } else {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_create_instance_chain: Failed to find "
                   "\'vkCreateInstance\'");
        // Couldn't find CreateInstance function!
        res = VK_ERROR_INITIALIZATION_FAILED;
    }

    if (res == VK_SUCCESS) {
        loader_init_instance_core_dispatch_table(&inst->disp->layer_inst_disp, next_gipa, *created_instance);
        inst->instance = *created_instance;
    }

    return res;
}

void loader_activate_instance_layer_extensions(struct loader_instance *inst, VkInstance created_inst) {
    loader_init_instance_extension_dispatch_table(&inst->disp->layer_inst_disp, inst->disp->layer_inst_disp.GetInstanceProcAddr,
                                                  created_inst);
}

VkResult loader_create_device_chain(const struct loader_physical_device_tramp *pd, const VkDeviceCreateInfo *pCreateInfo,
                                    const VkAllocationCallbacks *pAllocator, const struct loader_instance *inst,
                                    struct loader_device *dev) {
    uint32_t activated_layers = 0;
    VkLayerDeviceLink *layer_device_link_info;
    VkLayerDeviceCreateInfo chain_info;
    VkDeviceCreateInfo loader_create_info;
    VkResult res;

    PFN_vkGetDeviceProcAddr fpGDPA, nextGDPA = loader_gpa_device_internal;
    PFN_vkGetInstanceProcAddr fpGIPA, nextGIPA = loader_gpa_instance_internal;

    memcpy(&loader_create_info, pCreateInfo, sizeof(VkDeviceCreateInfo));

    layer_device_link_info = loader_stack_alloc(sizeof(VkLayerDeviceLink) * dev->activated_layer_list.count);
    if (!layer_device_link_info) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_create_device_chain: Failed to alloc Device objects"
                   " for layer.  Skipping Layer.");
        return VK_ERROR_OUT_OF_HOST_MEMORY;
    }

    if (dev->activated_layer_list.count > 0) {
        chain_info.sType = VK_STRUCTURE_TYPE_LOADER_DEVICE_CREATE_INFO;
        chain_info.function = VK_LAYER_LINK_INFO;
        chain_info.u.pLayerInfo = NULL;
        chain_info.pNext = loader_create_info.pNext;
        loader_create_info.pNext = &chain_info;

        // Create instance chain of enabled layers
        for (int32_t i = dev->activated_layer_list.count - 1; i >= 0; i--) {
            struct loader_layer_properties *layer_prop = &dev->activated_layer_list.list[i];
            loader_platform_dl_handle lib_handle;
            bool functions_in_interface = false;

            lib_handle = loader_open_layer_lib(inst, "device", layer_prop);
            if (!lib_handle) {
                continue;
            }

            // If we can negotiate an interface version, then we can also
            // get everything we need from the one function call, so try
            // that first, and see if we can get all the function pointers
            // necessary from that one call.
            if (NULL == layer_prop->functions.negotiate_layer_interface) {
                PFN_vkNegotiateLoaderLayerInterfaceVersion negotiate_interface = NULL;
                if (strlen(layer_prop->functions.str_negotiate_interface) == 0) {
                    negotiate_interface = (PFN_vkNegotiateLoaderLayerInterfaceVersion)loader_platform_get_proc_address(
                        lib_handle, "vkNegotiateLoaderLayerInterfaceVersion");
                } else {
                    negotiate_interface = (PFN_vkNegotiateLoaderLayerInterfaceVersion)loader_platform_get_proc_address(
                        lib_handle, layer_prop->functions.str_negotiate_interface);
                }

                if (NULL != negotiate_interface) {
                    layer_prop->functions.negotiate_layer_interface = negotiate_interface;

                    VkNegotiateLayerInterface interface_struct;

                    if (loader_get_layer_interface_version(negotiate_interface, &interface_struct)) {
                        // Go ahead and set the properites version to the
                        // correct value.
                        layer_prop->interface_version = interface_struct.loaderLayerInterfaceVersion;

                        // If the interface is 2 or newer, we have access to the
                        // new GetPhysicalDeviceProcAddr function, so grab it,
                        // and the other necessary functions, from the structure.
                        if (interface_struct.loaderLayerInterfaceVersion > 1) {
                            fpGIPA = interface_struct.pfnGetInstanceProcAddr;
                            fpGDPA = interface_struct.pfnGetDeviceProcAddr;
                            if (fpGIPA != NULL && fpGDPA) {
                                // We've set the functions, so make sure we
                                // don't do the unnecessary calls later.
                                functions_in_interface = true;
                            }
                        }
                    }
                }
            }

            if (!functions_in_interface) {
                if ((fpGIPA = layer_prop->functions.get_instance_proc_addr) == NULL) {
                    if (strlen(layer_prop->functions.str_gipa) == 0) {
                        fpGIPA = (PFN_vkGetInstanceProcAddr)loader_platform_get_proc_address(lib_handle, "vkGetInstanceProcAddr");
                        layer_prop->functions.get_instance_proc_addr = fpGIPA;
                    } else
                        fpGIPA =
                            (PFN_vkGetInstanceProcAddr)loader_platform_get_proc_address(lib_handle, layer_prop->functions.str_gipa);
                    if (!fpGIPA) {
                        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                                   "loader_create_device_chain: Failed to find "
                                   "\'vkGetInstanceProcAddr\' in layer %s.  Skipping"
                                   " layer.",
                                   layer_prop->lib_name);
                        continue;
                    }
                }
                if ((fpGDPA = layer_prop->functions.get_device_proc_addr) == NULL) {
                    if (strlen(layer_prop->functions.str_gdpa) == 0) {
                        fpGDPA = (PFN_vkGetDeviceProcAddr)loader_platform_get_proc_address(lib_handle, "vkGetDeviceProcAddr");
                        layer_prop->functions.get_device_proc_addr = fpGDPA;
                    } else
                        fpGDPA =
                            (PFN_vkGetDeviceProcAddr)loader_platform_get_proc_address(lib_handle, layer_prop->functions.str_gdpa);
                    if (!fpGDPA) {
                        loader_log(inst, VK_DEBUG_REPORT_INFORMATION_BIT_EXT, 0, "Failed to find vkGetDeviceProcAddr in layer %s",
                                   layer_prop->lib_name);
                        continue;
                    }
                }
            }
            layer_device_link_info[activated_layers].pNext = chain_info.u.pLayerInfo;
            layer_device_link_info[activated_layers].pfnNextGetInstanceProcAddr = nextGIPA;
            layer_device_link_info[activated_layers].pfnNextGetDeviceProcAddr = nextGDPA;
            chain_info.u.pLayerInfo = &layer_device_link_info[activated_layers];
            nextGIPA = fpGIPA;
            nextGDPA = fpGDPA;

            loader_log(inst, VK_DEBUG_REPORT_INFORMATION_BIT_EXT, 0, "Insert device layer %s (%s)", layer_prop->info.layerName,
                       layer_prop->lib_name);

            activated_layers++;
        }
    }

    VkDevice created_device = (VkDevice)dev;
    PFN_vkCreateDevice fpCreateDevice = (PFN_vkCreateDevice)nextGIPA(inst->instance, "vkCreateDevice");
    if (fpCreateDevice) {
        VkLayerDeviceCreateInfo create_info_disp;

        create_info_disp.sType = VK_STRUCTURE_TYPE_LOADER_DEVICE_CREATE_INFO;
        create_info_disp.function = VK_LOADER_DATA_CALLBACK;

        create_info_disp.u.pfnSetDeviceLoaderData = vkSetDeviceDispatch;

        create_info_disp.pNext = loader_create_info.pNext;
        loader_create_info.pNext = &create_info_disp;
        res = fpCreateDevice(pd->phys_dev, &loader_create_info, pAllocator, &created_device);
        if (res != VK_SUCCESS) {
            return res;
        }
        dev->chain_device = created_device;
    } else {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "loader_create_device_chain: Failed to find \'vkCreateDevice\' "
                   "in layer %s");
        // Couldn't find CreateDevice function!
        return VK_ERROR_INITIALIZATION_FAILED;
    }

    // Initialize device dispatch table
    loader_init_device_dispatch_table(&dev->loader_dispatch, nextGDPA, dev->chain_device);

    return res;
}

VkResult loader_validate_layers(const struct loader_instance *inst, const uint32_t layer_count,
                                const char *const *ppEnabledLayerNames, const struct loader_layer_list *list) {
    struct loader_layer_properties *prop;

    for (uint32_t i = 0; i < layer_count; i++) {
        VkStringErrorFlags result = vk_string_validate(MaxLoaderStringLength, ppEnabledLayerNames[i]);
        if (result != VK_STRING_ERROR_NONE) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_validate_layers: Device ppEnabledLayerNames "
                       "contains string that is too long or is badly formed");
            return VK_ERROR_LAYER_NOT_PRESENT;
        }

        prop = loader_get_layer_property(ppEnabledLayerNames[i], list);
        if (!prop) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_validate_layers: Layer %d does not exist in "
                       "the list of available layers",
                       i);
            return VK_ERROR_LAYER_NOT_PRESENT;
        }
    }
    return VK_SUCCESS;
}

VkResult loader_validate_instance_extensions(const struct loader_instance *inst, const struct loader_extension_list *icd_exts,
                                             const struct loader_layer_list *instance_layers,
                                             const VkInstanceCreateInfo *pCreateInfo) {
    VkExtensionProperties *extension_prop;
    struct loader_layer_properties *layer_prop;

    for (uint32_t i = 0; i < pCreateInfo->enabledExtensionCount; i++) {
        VkStringErrorFlags result = vk_string_validate(MaxLoaderStringLength, pCreateInfo->ppEnabledExtensionNames[i]);
        if (result != VK_STRING_ERROR_NONE) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_validate_instance_extensions: Instance "
                       "ppEnabledExtensionNames contains "
                       "string that is too long or is badly formed");
            return VK_ERROR_EXTENSION_NOT_PRESENT;
        }

        // See if the extension is in the list of supported extensions
        bool found = false;
        for (uint32_t j = 0; LOADER_INSTANCE_EXTENSIONS[j] != NULL; j++) {
            if (strcmp(pCreateInfo->ppEnabledExtensionNames[i], LOADER_INSTANCE_EXTENSIONS[j]) == 0) {
                found = true;
                break;
            }
        }

        // If it isn't in the list, return an error
        if (!found) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_validate_instance_extensions: Extension %d "
                       "not found in list of available extensions.",
                       i);
            return VK_ERROR_EXTENSION_NOT_PRESENT;
        }

        extension_prop = get_extension_property(pCreateInfo->ppEnabledExtensionNames[i], icd_exts);

        if (extension_prop) {
            continue;
        }

        extension_prop = NULL;

        /* Not in global list, search layer extension lists */
        for (uint32_t j = 0; j < pCreateInfo->enabledLayerCount; j++) {
            layer_prop = loader_get_layer_property(pCreateInfo->ppEnabledLayerNames[j], instance_layers);
            if (!layer_prop) {
                /* Should NOT get here, loader_validate_layers
                 * should have already filtered this case out.
                 */
                continue;
            }

            extension_prop = get_extension_property(pCreateInfo->ppEnabledExtensionNames[i], &layer_prop->instance_extension_list);
            if (extension_prop) {
                /* Found the extension in one of the layers enabled by the app.
                 */
                break;
            }
        }

        if (!extension_prop) {
            // Didn't find extension name in any of the global layers, error out
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_validate_instance_extensions: Extension %d "
                       "not found in enabled layer list extensions.",
                       i);
            return VK_ERROR_EXTENSION_NOT_PRESENT;
        }
    }
    return VK_SUCCESS;
}

VkResult loader_validate_device_extensions(struct loader_physical_device_tramp *phys_dev,
                                           const struct loader_layer_list *activated_device_layers,
                                           const struct loader_extension_list *icd_exts, const VkDeviceCreateInfo *pCreateInfo) {
    VkExtensionProperties *extension_prop;
    struct loader_layer_properties *layer_prop;

    for (uint32_t i = 0; i < pCreateInfo->enabledExtensionCount; i++) {
        VkStringErrorFlags result = vk_string_validate(MaxLoaderStringLength, pCreateInfo->ppEnabledExtensionNames[i]);
        if (result != VK_STRING_ERROR_NONE) {
            loader_log(phys_dev->this_instance, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_validate_device_extensions: Device "
                       "ppEnabledExtensionNames contains "
                       "string that is too long or is badly formed");
            return VK_ERROR_EXTENSION_NOT_PRESENT;
        }

        const char *extension_name = pCreateInfo->ppEnabledExtensionNames[i];
        extension_prop = get_extension_property(extension_name, icd_exts);

        if (extension_prop) {
            continue;
        }

        // Not in global list, search activated layer extension lists
        for (uint32_t j = 0; j < activated_device_layers->count; j++) {
            layer_prop = &activated_device_layers->list[j];

            extension_prop = get_dev_extension_property(extension_name, &layer_prop->device_extension_list);
            if (extension_prop) {
                // Found the extension in one of the layers enabled by the app.
                break;
            }
        }

        if (!extension_prop) {
            // Didn't find extension name in any of the device layers, error out
            loader_log(phys_dev->this_instance, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "loader_validate_device_extensions: Extension %d "
                       "not found in enabled layer list extensions.",
                       i);
            return VK_ERROR_EXTENSION_NOT_PRESENT;
        }
    }
    return VK_SUCCESS;
}

// Terminator functions for the Instance chain
// All named terminator_<Vulakn API name>
VKAPI_ATTR VkResult VKAPI_CALL terminator_CreateInstance(const VkInstanceCreateInfo *pCreateInfo,
                                                         const VkAllocationCallbacks *pAllocator, VkInstance *pInstance) {
    struct loader_icd_term *icd_term;
    VkExtensionProperties *prop;
    char **filtered_extension_names = NULL;
    VkInstanceCreateInfo icd_create_info;
    VkResult res = VK_SUCCESS;
    bool one_icd_successful = false;

    struct loader_instance *ptr_instance = (struct loader_instance *)*pInstance;
    memcpy(&icd_create_info, pCreateInfo, sizeof(icd_create_info));

    icd_create_info.enabledLayerCount = 0;
    icd_create_info.ppEnabledLayerNames = NULL;

    // NOTE: Need to filter the extensions to only those supported by the ICD.
    //       No ICD will advertise support for layers. An ICD library could
    //       support a layer, but it would be independent of the actual ICD,
    //       just in the same library.
    filtered_extension_names = loader_stack_alloc(pCreateInfo->enabledExtensionCount * sizeof(char *));
    if (!filtered_extension_names) {
        loader_log(ptr_instance, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "terminator_CreateInstance: Failed create extension name "
                   "array for %d extensions",
                   pCreateInfo->enabledExtensionCount);
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }
    icd_create_info.ppEnabledExtensionNames = (const char *const *)filtered_extension_names;

    for (uint32_t i = 0; i < ptr_instance->icd_tramp_list.count; i++) {
        icd_term = loader_icd_add(ptr_instance, &ptr_instance->icd_tramp_list.scanned_list[i]);
        if (NULL == icd_term) {
            loader_log(ptr_instance, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "terminator_CreateInstance: Failed to add ICD %d to ICD "
                       "trampoline list.",
                       i);
            res = VK_ERROR_OUT_OF_HOST_MEMORY;
            goto out;
        }

        icd_create_info.enabledExtensionCount = 0;
        struct loader_extension_list icd_exts;

        loader_log(ptr_instance, VK_DEBUG_REPORT_DEBUG_BIT_EXT, 0, "Build ICD instance extension list");
        // traverse scanned icd list adding non-duplicate extensions to the
        // list
        res = loader_init_generic_list(ptr_instance, (struct loader_generic_list *)&icd_exts, sizeof(VkExtensionProperties));
        if (VK_ERROR_OUT_OF_HOST_MEMORY == res) {
            // If out of memory, bail immediately.
            goto out;
        } else if (VK_SUCCESS != res) {
            // Something bad happened with this ICD, so free it and try the
            // next.
            ptr_instance->icd_terms = icd_term->next;
            icd_term->next = NULL;
            loader_icd_destroy(ptr_instance, icd_term, pAllocator);
            continue;
        }

        res = loader_add_instance_extensions(ptr_instance, icd_term->scanned_icd->EnumerateInstanceExtensionProperties,
                                             icd_term->scanned_icd->lib_name, &icd_exts);
        if (VK_SUCCESS != res) {
            loader_destroy_generic_list(ptr_instance, (struct loader_generic_list *)&icd_exts);
            if (VK_ERROR_OUT_OF_HOST_MEMORY == res) {
                // If out of memory, bail immediately.
                goto out;
            } else {
                // Something bad happened with this ICD, so free it and try
                // the next.
                ptr_instance->icd_terms = icd_term->next;
                icd_term->next = NULL;
                loader_icd_destroy(ptr_instance, icd_term, pAllocator);
                continue;
            }
        }

        for (uint32_t j = 0; j < pCreateInfo->enabledExtensionCount; j++) {
            prop = get_extension_property(pCreateInfo->ppEnabledExtensionNames[j], &icd_exts);
            if (prop) {
                filtered_extension_names[icd_create_info.enabledExtensionCount] = (char *)pCreateInfo->ppEnabledExtensionNames[j];
                icd_create_info.enabledExtensionCount++;
            }
        }

        loader_destroy_generic_list(ptr_instance, (struct loader_generic_list *)&icd_exts);

        VkResult icd_result =
            ptr_instance->icd_tramp_list.scanned_list[i].CreateInstance(&icd_create_info, pAllocator, &(icd_term->instance));
        if (VK_ERROR_OUT_OF_HOST_MEMORY == icd_result) {
            // If out of memory, bail immediately.
            res = VK_ERROR_OUT_OF_HOST_MEMORY;
            goto out;
        } else if (VK_SUCCESS != icd_result) {
            loader_log(ptr_instance, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "terminator_CreateInstance: Failed to CreateInstance in "
                       "ICD %d.  Skipping ICD.",
                       i);
            ptr_instance->icd_terms = icd_term->next;
            icd_term->next = NULL;
            loader_icd_destroy(ptr_instance, icd_term, pAllocator);
            continue;
        }

        if (!loader_icd_init_entrys(icd_term, icd_term->instance,
                                    ptr_instance->icd_tramp_list.scanned_list[i].GetInstanceProcAddr)) {
            loader_log(ptr_instance, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "terminator_CreateInstance: Failed to CreateInstance and find "
                       "entrypoints with ICD.  Skipping ICD.");
            continue;
        }

        // If we made it this far, at least one ICD was successful
        one_icd_successful = true;
    }

    // If no ICDs were added to instance list and res is unchanged
    // from it's initial value, the loader was unable to find
    // a suitable ICD.
    if (VK_SUCCESS == res && (ptr_instance->icd_terms == NULL || !one_icd_successful)) {
        res = VK_ERROR_INCOMPATIBLE_DRIVER;
    }

out:

    if (VK_SUCCESS != res) {
        while (NULL != ptr_instance->icd_terms) {
            icd_term = ptr_instance->icd_terms;
            ptr_instance->icd_terms = icd_term->next;
            if (NULL != icd_term->instance) {
                icd_term->DestroyInstance(icd_term->instance, pAllocator);
            }
            loader_icd_destroy(ptr_instance, icd_term, pAllocator);
        }
    }

    return res;
}

VKAPI_ATTR void VKAPI_CALL terminator_DestroyInstance(VkInstance instance, const VkAllocationCallbacks *pAllocator) {
    struct loader_instance *ptr_instance = loader_instance(instance);
    if (NULL == ptr_instance) {
        return;
    }
    struct loader_icd_term *icd_terms = ptr_instance->icd_terms;
    struct loader_icd_term *next_icd_term;

    // Remove this instance from the list of instances:
    struct loader_instance *prev = NULL;
    struct loader_instance *next = loader.instances;
    while (next != NULL) {
        if (next == ptr_instance) {
            // Remove this instance from the list:
            if (prev)
                prev->next = next->next;
            else
                loader.instances = next->next;
            break;
        }
        prev = next;
        next = next->next;
    }

    while (NULL != icd_terms) {
        if (icd_terms->instance) {
            icd_terms->DestroyInstance(icd_terms->instance, pAllocator);
        }
        next_icd_term = icd_terms->next;
        icd_terms->instance = VK_NULL_HANDLE;
        loader_icd_destroy(ptr_instance, icd_terms, pAllocator);

        icd_terms = next_icd_term;
    }

    loader_delete_layer_properties(ptr_instance, &ptr_instance->instance_layer_list);
    loader_scanned_icd_clear(ptr_instance, &ptr_instance->icd_tramp_list);
    loader_destroy_generic_list(ptr_instance, (struct loader_generic_list *)&ptr_instance->ext_list);
    if (NULL != ptr_instance->phys_devs_term) {
        for (uint32_t i = 0; i < ptr_instance->phys_dev_count_term; i++) {
            loader_instance_heap_free(ptr_instance, ptr_instance->phys_devs_term[i]);
        }
        loader_instance_heap_free(ptr_instance, ptr_instance->phys_devs_term);
    }
    loader_free_dev_ext_table(ptr_instance);
    loader_free_phys_dev_ext_table(ptr_instance);
}

VKAPI_ATTR VkResult VKAPI_CALL terminator_CreateDevice(VkPhysicalDevice physicalDevice, const VkDeviceCreateInfo *pCreateInfo,
                                                       const VkAllocationCallbacks *pAllocator, VkDevice *pDevice) {
    VkResult res = VK_SUCCESS;
    struct loader_physical_device_term *phys_dev_term;
    phys_dev_term = (struct loader_physical_device_term *)physicalDevice;
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;

    struct loader_device *dev = (struct loader_device *)*pDevice;
    PFN_vkCreateDevice fpCreateDevice = icd_term->CreateDevice;
    struct loader_extension_list icd_exts;

    dev->phys_dev_term = phys_dev_term;

    icd_exts.list = NULL;

    if (fpCreateDevice == NULL) {
        loader_log(icd_term->this_instance, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "terminator_CreateDevice: No vkCreateDevice command exposed "
                   "by ICD %s",
                   icd_term->scanned_icd->lib_name);
        res = VK_ERROR_INITIALIZATION_FAILED;
        goto out;
    }

    VkDeviceCreateInfo localCreateInfo;
    memcpy(&localCreateInfo, pCreateInfo, sizeof(localCreateInfo));

    // NOTE: Need to filter the extensions to only those supported by the ICD.
    //       No ICD will advertise support for layers. An ICD library could
    //       support a layer, but it would be independent of the actual ICD,
    //       just in the same library.
    char **filtered_extension_names = NULL;
    filtered_extension_names = loader_stack_alloc(pCreateInfo->enabledExtensionCount * sizeof(char *));
    if (NULL == filtered_extension_names) {
        loader_log(icd_term->this_instance, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "terminator_CreateDevice: Failed to create extension name "
                   "storage for %d extensions %d",
                   pCreateInfo->enabledExtensionCount);
        return VK_ERROR_OUT_OF_HOST_MEMORY;
    }

    localCreateInfo.enabledLayerCount = 0;
    localCreateInfo.ppEnabledLayerNames = NULL;

    localCreateInfo.enabledExtensionCount = 0;
    localCreateInfo.ppEnabledExtensionNames = (const char *const *)filtered_extension_names;

    // Get the physical device (ICD) extensions
    res = loader_init_generic_list(icd_term->this_instance, (struct loader_generic_list *)&icd_exts, sizeof(VkExtensionProperties));
    if (VK_SUCCESS != res) {
        goto out;
    }

    res = loader_add_device_extensions(icd_term->this_instance, icd_term->EnumerateDeviceExtensionProperties,
                                       phys_dev_term->phys_dev, icd_term->scanned_icd->lib_name, &icd_exts);
    if (res != VK_SUCCESS) {
        goto out;
    }

    for (uint32_t i = 0; i < pCreateInfo->enabledExtensionCount; i++) {
        const char *extension_name = pCreateInfo->ppEnabledExtensionNames[i];
        VkExtensionProperties *prop = get_extension_property(extension_name, &icd_exts);
        if (prop) {
            filtered_extension_names[localCreateInfo.enabledExtensionCount] = (char *)extension_name;
            localCreateInfo.enabledExtensionCount++;
        } else {
            loader_log(icd_term->this_instance, VK_DEBUG_REPORT_WARNING_BIT_EXT, 0,
                       "vkCreateDevice extension %s not available for "
                       "devices associated with ICD %s",
                       extension_name, icd_term->scanned_icd->lib_name);
        }
    }

    res = fpCreateDevice(phys_dev_term->phys_dev, &localCreateInfo, pAllocator, &dev->icd_device);
    if (res != VK_SUCCESS) {
        loader_log(icd_term->this_instance, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "terminator_CreateDevice: Failed in ICD %s vkCreateDevice"
                   "call",
                   icd_term->scanned_icd->lib_name);
        goto out;
    }

    *pDevice = dev->icd_device;
    loader_add_logical_device(icd_term->this_instance, icd_term, dev);

    /* Init dispatch pointer in new device object */
    loader_init_dispatch(*pDevice, &dev->loader_dispatch);

out:
    if (NULL != icd_exts.list) {
        loader_destroy_generic_list(icd_term->this_instance, (struct loader_generic_list *)&icd_exts);
    }

    return res;
}

VkResult setupLoaderTrampPhysDevs(VkInstance instance) {
    VkResult res = VK_SUCCESS;
    VkPhysicalDevice *local_phys_devs = NULL;
    struct loader_instance *inst;
    uint32_t total_count = 0;
    struct loader_physical_device_tramp **new_phys_devs = NULL;

    inst = loader_get_instance(instance);
    if (NULL == inst) {
        res = VK_ERROR_INITIALIZATION_FAILED;
        goto out;
    }
    total_count = inst->total_gpu_count;

    // Create an array for the new physical devices, which will be stored
    // in the instance for the trampoline code.
    new_phys_devs = (struct loader_physical_device_tramp **)loader_instance_heap_alloc(
        inst, total_count * sizeof(struct loader_physical_device_tramp *), VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (NULL == new_phys_devs) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "setupLoaderTrampPhysDevs:  Failed to allocate new physical device"
                   " array of size %d",
                   total_count);
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }
    memset(new_phys_devs, 0, total_count * sizeof(struct loader_physical_device_tramp *));

    // Create a temporary array (on the stack) to keep track of the
    // returned VkPhysicalDevice values.
    local_phys_devs = loader_stack_alloc(sizeof(VkPhysicalDevice) * total_count);
    if (NULL == local_phys_devs) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "setupLoaderTrampPhysDevs:  Failed to allocate local "
                   "physical device array of size %d",
                   total_count);
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }
    memset(local_phys_devs, 0, sizeof(VkPhysicalDevice) * total_count);

    res = inst->disp->layer_inst_disp.EnumeratePhysicalDevices(instance, &total_count, local_phys_devs);
    if (VK_SUCCESS != res) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "setupLoaderTrampPhysDevs:  Failed during dispatch call "
                   "of \'vkEnumeratePhysicalDevices\' to lower layers or "
                   "loader.");
        goto out;
    }

    // Copy or create everything to fill the new array of physical devices
    for (uint32_t new_idx = 0; new_idx < total_count; new_idx++) {
        // Check if this physical device is already in the old buffer
        for (uint32_t old_idx = 0; old_idx < inst->phys_dev_count_tramp; old_idx++) {
            if (local_phys_devs[new_idx] == inst->phys_devs_tramp[old_idx]->phys_dev) {
                new_phys_devs[new_idx] = inst->phys_devs_tramp[old_idx];
                break;
            }
        }

        // If this physical device isn't in the old buffer, create it
        if (NULL == new_phys_devs[new_idx]) {
            new_phys_devs[new_idx] = (struct loader_physical_device_tramp *)loader_instance_heap_alloc(
                inst, sizeof(struct loader_physical_device_tramp), VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
            if (NULL == new_phys_devs[new_idx]) {
                loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                           "setupLoaderTrampPhysDevs:  Failed to allocate "
                           "physical device trampoline object %d",
                           new_idx);
                total_count = new_idx;
                res = VK_ERROR_OUT_OF_HOST_MEMORY;
                goto out;
            }

            // Initialize the new physicalDevice object
            loader_set_dispatch((void *)new_phys_devs[new_idx], inst->disp);
            new_phys_devs[new_idx]->this_instance = inst;
            new_phys_devs[new_idx]->phys_dev = local_phys_devs[new_idx];
        }
    }

out:

    if (VK_SUCCESS != res) {
        if (NULL != new_phys_devs) {
            for (uint32_t i = 0; i < total_count; i++) {
                loader_instance_heap_free(inst, new_phys_devs[i]);
            }
            loader_instance_heap_free(inst, new_phys_devs);
        }
        total_count = 0;
    } else {
        // Free everything that didn't carry over to the new array of
        // physical devices
        if (NULL != inst->phys_devs_tramp) {
            for (uint32_t i = 0; i < inst->phys_dev_count_tramp; i++) {
                bool found = false;
                for (uint32_t j = 0; j < total_count; j++) {
                    if (inst->phys_devs_tramp[i] == new_phys_devs[j]) {
                        found = true;
                        break;
                    }
                }
                if (!found) {
                    loader_instance_heap_free(inst, inst->phys_devs_tramp[i]);
                }
            }
            loader_instance_heap_free(inst, inst->phys_devs_tramp);
        }

        // Swap in the new physical device list
        inst->phys_dev_count_tramp = total_count;
        inst->phys_devs_tramp = new_phys_devs;
    }

    return res;
}

VkResult setupLoaderTermPhysDevs(struct loader_instance *inst) {
    VkResult res = VK_SUCCESS;
    struct loader_icd_term *icd_term;
    struct loader_phys_dev_per_icd *icd_phys_dev_array = NULL;
    struct loader_physical_device_term **new_phys_devs = NULL;

    inst->total_gpu_count = 0;

    // Allocate something to store the physical device characteristics
    // that we read from each ICD.
    icd_phys_dev_array =
        (struct loader_phys_dev_per_icd *)loader_stack_alloc(sizeof(struct loader_phys_dev_per_icd) * inst->total_icd_count);
    if (NULL == icd_phys_dev_array) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "setupLoaderTermPhysDevs:  Failed to allocate temporary "
                   "ICD Physical device info array of size %d",
                   inst->total_gpu_count);
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }
    memset(icd_phys_dev_array, 0, sizeof(struct loader_phys_dev_per_icd) * inst->total_icd_count);
    icd_term = inst->icd_terms;

    // For each ICD, query the number of physical devices, and then get an
    // internal value for those physical devices.
    for (uint32_t icd_idx = 0; NULL != icd_term; icd_term = icd_term->next, icd_idx++) {
        res = icd_term->EnumeratePhysicalDevices(icd_term->instance, &icd_phys_dev_array[icd_idx].count, NULL);
        if (VK_SUCCESS != res) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "setupLoaderTermPhysDevs:  Call to "
                       "ICD %d's \'vkEnumeratePhysicalDevices\' failed with"
                       " error 0x%08x",
                       icd_idx, res);
            goto out;
        }

        icd_phys_dev_array[icd_idx].phys_devs =
            (VkPhysicalDevice *)loader_stack_alloc(icd_phys_dev_array[icd_idx].count * sizeof(VkPhysicalDevice));
        if (NULL == icd_phys_dev_array[icd_idx].phys_devs) {
            loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                       "setupLoaderTermPhysDevs:  Failed to allocate temporary "
                       "ICD Physical device array for ICD %d of size %d",
                       icd_idx, inst->total_gpu_count);
            res = VK_ERROR_OUT_OF_HOST_MEMORY;
            goto out;
        }

        res = icd_term->EnumeratePhysicalDevices(icd_term->instance, &(icd_phys_dev_array[icd_idx].count),
                                                 icd_phys_dev_array[icd_idx].phys_devs);
        if (VK_SUCCESS != res) {
            goto out;
        }
        inst->total_gpu_count += icd_phys_dev_array[icd_idx].count;
        icd_phys_dev_array[icd_idx].this_icd_term = icd_term;
    }

    if (0 == inst->total_gpu_count) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "setupLoaderTermPhysDevs:  Failed to detect any valid"
                   " GPUs in the current config");
        res = VK_ERROR_INITIALIZATION_FAILED;
        goto out;
    }

    new_phys_devs = loader_instance_heap_alloc(inst, sizeof(struct loader_physical_device_term *) * inst->total_gpu_count,
                                               VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
    if (NULL == new_phys_devs) {
        loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "setupLoaderTermPhysDevs:  Failed to allocate new physical"
                   " device array of size %d",
                   inst->total_gpu_count);
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }
    memset(new_phys_devs, 0, sizeof(struct loader_physical_device_term *) * inst->total_gpu_count);

    // Copy or create everything to fill the new array of physical devices
    uint32_t idx = 0;
    for (uint32_t icd_idx = 0; icd_idx < inst->total_icd_count; icd_idx++) {
        for (uint32_t pd_idx = 0; pd_idx < icd_phys_dev_array[icd_idx].count; pd_idx++) {
            // Check if this physical device is already in the old buffer
            if (NULL != inst->phys_devs_term) {
                for (uint32_t old_idx = 0; old_idx < inst->phys_dev_count_term; old_idx++) {
                    if (icd_phys_dev_array[icd_idx].phys_devs[pd_idx] == inst->phys_devs_term[old_idx]->phys_dev) {
                        new_phys_devs[idx] = inst->phys_devs_term[old_idx];
                        break;
                    }
                }
            }
            // If this physical device isn't in the old buffer, then we
            // need to create it.
            if (NULL == new_phys_devs[idx]) {
                new_phys_devs[idx] = loader_instance_heap_alloc(inst, sizeof(struct loader_physical_device_term),
                                                                VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
                if (NULL == new_phys_devs[idx]) {
                    loader_log(inst, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                               "setupLoaderTermPhysDevs:  Failed to allocate "
                               "physical device terminator object %d",
                               idx);
                    inst->total_gpu_count = idx;
                    res = VK_ERROR_OUT_OF_HOST_MEMORY;
                    goto out;
                }

                loader_set_dispatch((void *)new_phys_devs[idx], inst->disp);
                new_phys_devs[idx]->this_icd_term = icd_phys_dev_array[icd_idx].this_icd_term;
                new_phys_devs[idx]->icd_index = (uint8_t)(icd_idx);
                new_phys_devs[idx]->phys_dev = icd_phys_dev_array[icd_idx].phys_devs[pd_idx];
            }
            idx++;
        }
    }

out:

    if (VK_SUCCESS != res) {
        if (NULL != new_phys_devs) {
            // We've encountered an error, so we should free the new buffers.
            for (uint32_t i = 0; i < inst->total_gpu_count; i++) {
                loader_instance_heap_free(inst, new_phys_devs[i]);
            }
            loader_instance_heap_free(inst, new_phys_devs);
        }
        if (NULL != inst->phys_devs_term) {
            loader_instance_heap_free(inst, inst->phys_devs_term);
        }
        inst->total_gpu_count = 0;
    } else {
        // Free everything that didn't carry over to the new array of
        // physical devices.  Everything else will have been copied over
        // to the new array.
        if (NULL != inst->phys_devs_term) {
            for (uint32_t cur_pd = 0; cur_pd < inst->phys_dev_count_term; cur_pd++) {
                bool found = false;
                for (uint32_t new_pd_idx = 0; new_pd_idx < inst->total_gpu_count; new_pd_idx++) {
                    if (inst->phys_devs_term[cur_pd] == new_phys_devs[new_pd_idx]) {
                        found = true;
                        break;
                    }
                }
                if (!found) {
                    loader_instance_heap_free(inst, inst->phys_devs_term[cur_pd]);
                }
            }
            loader_instance_heap_free(inst, inst->phys_devs_term);
        }

        // Swap out old and new devices list
        inst->phys_dev_count_term = inst->total_gpu_count;
        inst->phys_devs_term = new_phys_devs;
    }

    return res;
}

VKAPI_ATTR VkResult VKAPI_CALL terminator_EnumeratePhysicalDevices(VkInstance instance, uint32_t *pPhysicalDeviceCount,
                                                                   VkPhysicalDevice *pPhysicalDevices) {
    struct loader_instance *inst = (struct loader_instance *)instance;
    VkResult res = VK_SUCCESS;

    // Only do the setup if we're re-querying the number of devices, or
    // our count is currently 0.
    if (NULL == pPhysicalDevices || 0 == inst->total_gpu_count) {
        res = setupLoaderTermPhysDevs(inst);
        if (VK_SUCCESS != res) {
            goto out;
        }
    }

    uint32_t copy_count = inst->total_gpu_count;
    if (NULL != pPhysicalDevices) {
        if (copy_count > *pPhysicalDeviceCount) {
            copy_count = *pPhysicalDeviceCount;
            res = VK_INCOMPLETE;
        }

        for (uint32_t i = 0; i < copy_count; i++) {
            pPhysicalDevices[i] = (VkPhysicalDevice)inst->phys_devs_term[i];
        }
    }

    *pPhysicalDeviceCount = copy_count;

out:

    return res;
}

VKAPI_ATTR void VKAPI_CALL terminator_GetPhysicalDeviceProperties(VkPhysicalDevice physicalDevice,
                                                                  VkPhysicalDeviceProperties *pProperties) {
    struct loader_physical_device_term *phys_dev_term = (struct loader_physical_device_term *)physicalDevice;
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;
    if (NULL != icd_term->GetPhysicalDeviceProperties) {
        icd_term->GetPhysicalDeviceProperties(phys_dev_term->phys_dev, pProperties);
    }
}

VKAPI_ATTR void VKAPI_CALL terminator_GetPhysicalDeviceQueueFamilyProperties(VkPhysicalDevice physicalDevice,
                                                                             uint32_t *pQueueFamilyPropertyCount,
                                                                             VkQueueFamilyProperties *pProperties) {
    struct loader_physical_device_term *phys_dev_term = (struct loader_physical_device_term *)physicalDevice;
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;
    if (NULL != icd_term->GetPhysicalDeviceQueueFamilyProperties) {
        icd_term->GetPhysicalDeviceQueueFamilyProperties(phys_dev_term->phys_dev, pQueueFamilyPropertyCount, pProperties);
    }
}

VKAPI_ATTR void VKAPI_CALL terminator_GetPhysicalDeviceMemoryProperties(VkPhysicalDevice physicalDevice,
                                                                        VkPhysicalDeviceMemoryProperties *pProperties) {
    struct loader_physical_device_term *phys_dev_term = (struct loader_physical_device_term *)physicalDevice;
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;
    if (NULL != icd_term->GetPhysicalDeviceMemoryProperties) {
        icd_term->GetPhysicalDeviceMemoryProperties(phys_dev_term->phys_dev, pProperties);
    }
}

VKAPI_ATTR void VKAPI_CALL terminator_GetPhysicalDeviceFeatures(VkPhysicalDevice physicalDevice,
                                                                VkPhysicalDeviceFeatures *pFeatures) {
    struct loader_physical_device_term *phys_dev_term = (struct loader_physical_device_term *)physicalDevice;
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;
    if (NULL != icd_term->GetPhysicalDeviceFeatures) {
        icd_term->GetPhysicalDeviceFeatures(phys_dev_term->phys_dev, pFeatures);
    }
}

VKAPI_ATTR void VKAPI_CALL terminator_GetPhysicalDeviceFormatProperties(VkPhysicalDevice physicalDevice, VkFormat format,
                                                                        VkFormatProperties *pFormatInfo) {
    struct loader_physical_device_term *phys_dev_term = (struct loader_physical_device_term *)physicalDevice;
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;
    if (NULL != icd_term->GetPhysicalDeviceFormatProperties) {
        icd_term->GetPhysicalDeviceFormatProperties(phys_dev_term->phys_dev, format, pFormatInfo);
    }
}

VKAPI_ATTR VkResult VKAPI_CALL terminator_GetPhysicalDeviceImageFormatProperties(VkPhysicalDevice physicalDevice, VkFormat format,
                                                                                 VkImageType type, VkImageTiling tiling,
                                                                                 VkImageUsageFlags usage, VkImageCreateFlags flags,
                                                                                 VkImageFormatProperties *pImageFormatProperties) {
    struct loader_physical_device_term *phys_dev_term = (struct loader_physical_device_term *)physicalDevice;
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;
    if (NULL == icd_term->GetPhysicalDeviceImageFormatProperties) {
        loader_log(icd_term->this_instance, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
                   "Encountered the vkEnumerateDeviceLayerProperties "
                   "terminator.  This means a layer improperly continued.");
        return VK_ERROR_INITIALIZATION_FAILED;
    }
    return icd_term->GetPhysicalDeviceImageFormatProperties(phys_dev_term->phys_dev, format, type, tiling, usage, flags,
                                                            pImageFormatProperties);
}

VKAPI_ATTR void VKAPI_CALL terminator_GetPhysicalDeviceSparseImageFormatProperties(VkPhysicalDevice physicalDevice, VkFormat format,
                                                                                   VkImageType type, VkSampleCountFlagBits samples,
                                                                                   VkImageUsageFlags usage, VkImageTiling tiling,
                                                                                   uint32_t *pNumProperties,
                                                                                   VkSparseImageFormatProperties *pProperties) {
    struct loader_physical_device_term *phys_dev_term = (struct loader_physical_device_term *)physicalDevice;
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;
    if (NULL != icd_term->GetPhysicalDeviceSparseImageFormatProperties) {
        icd_term->GetPhysicalDeviceSparseImageFormatProperties(phys_dev_term->phys_dev, format, type, samples, usage, tiling,
                                                               pNumProperties, pProperties);
    }
}

VKAPI_ATTR VkResult VKAPI_CALL terminator_EnumerateDeviceExtensionProperties(VkPhysicalDevice physicalDevice,
                                                                             const char *pLayerName, uint32_t *pPropertyCount,
                                                                             VkExtensionProperties *pProperties) {
    struct loader_physical_device_term *phys_dev_term;

    struct loader_layer_list implicit_layer_list = {0};
    struct loader_extension_list all_exts = {0};
    struct loader_extension_list icd_exts = {0};

    assert(pLayerName == NULL || strlen(pLayerName) == 0);

    /* Any layer or trampoline wrapping should be removed at this point in time
     * can just cast to the expected type for VkPhysicalDevice. */
    phys_dev_term = (struct loader_physical_device_term *)physicalDevice;

    /* this case is during the call down the instance chain with pLayerName
     * == NULL*/
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;
    uint32_t icd_ext_count = *pPropertyCount;
    VkResult res;

    /* get device extensions */
    res = icd_term->EnumerateDeviceExtensionProperties(phys_dev_term->phys_dev, NULL, &icd_ext_count, pProperties);
    if (res != VK_SUCCESS) {
        goto out;
    }

    if (!loader_init_layer_list(icd_term->this_instance, &implicit_layer_list)) {
        res = VK_ERROR_OUT_OF_HOST_MEMORY;
        goto out;
    }

    loader_add_layer_implicit(icd_term->this_instance, VK_LAYER_TYPE_INSTANCE_IMPLICIT, &implicit_layer_list,
                              &icd_term->this_instance->instance_layer_list);
    /* we need to determine which implicit layers are active,
     * and then add their extensions. This can't be cached as
     * it depends on results of environment variables (which can change).
     */
    if (pProperties != NULL) {
        /* initialize dev_extension list within the physicalDevice object */
        res = loader_init_device_extensions(icd_term->this_instance, phys_dev_term, icd_ext_count, pProperties, &icd_exts);
        if (res != VK_SUCCESS) {
            goto out;
        }

        /* we need to determine which implicit layers are active,
         * and then add their extensions. This can't be cached as
         * it depends on results of environment variables (which can
         * change).
         */
        res = loader_add_to_ext_list(icd_term->this_instance, &all_exts, icd_exts.count, icd_exts.list);
        if (res != VK_SUCCESS) {
            goto out;
        }

        loader_add_layer_implicit(icd_term->this_instance, VK_LAYER_TYPE_INSTANCE_IMPLICIT, &implicit_layer_list,
                                  &icd_term->this_instance->instance_layer_list);

        for (uint32_t i = 0; i < implicit_layer_list.count; i++) {
            for (uint32_t j = 0; j < implicit_layer_list.list[i].device_extension_list.count; j++) {
                res = loader_add_to_ext_list(icd_term->this_instance, &all_exts, 1,
                                             &implicit_layer_list.list[i].device_extension_list.list[j].props);
                if (res != VK_SUCCESS) {
                    goto out;
                }
            }
        }
        uint32_t capacity = *pPropertyCount;
        VkExtensionProperties *props = pProperties;

        for (uint32_t i = 0; i < all_exts.count && i < capacity; i++) {
            props[i] = all_exts.list[i];
        }
        /* wasn't enough space for the extensions, we did partial copy now
         * return VK_INCOMPLETE */
        if (capacity < all_exts.count) {
            res = VK_INCOMPLETE;
        } else {
            *pPropertyCount = all_exts.count;
        }
    } else {
        /* just return the count; need to add in the count of implicit layer
         * extensions
         * don't worry about duplicates being added in the count */
        *pPropertyCount = icd_ext_count;

        for (uint32_t i = 0; i < implicit_layer_list.count; i++) {
            *pPropertyCount += implicit_layer_list.list[i].device_extension_list.count;
        }
        res = VK_SUCCESS;
    }

out:

    if (NULL != implicit_layer_list.list) {
        loader_destroy_generic_list(icd_term->this_instance, (struct loader_generic_list *)&implicit_layer_list);
    }
    if (NULL != all_exts.list) {
        loader_destroy_generic_list(icd_term->this_instance, (struct loader_generic_list *)&all_exts);
    }
    if (NULL != icd_exts.list) {
        loader_destroy_generic_list(icd_term->this_instance, (struct loader_generic_list *)&icd_exts);
    }

    return res;
}

VKAPI_ATTR VkResult VKAPI_CALL terminator_EnumerateDeviceLayerProperties(VkPhysicalDevice physicalDevice, uint32_t *pPropertyCount,
                                                                         VkLayerProperties *pProperties) {
    struct loader_physical_device_term *phys_dev_term = (struct loader_physical_device_term *)physicalDevice;
    struct loader_icd_term *icd_term = phys_dev_term->this_icd_term;
    loader_log(icd_term->this_instance, VK_DEBUG_REPORT_ERROR_BIT_EXT, 0,
               "Encountered the vkEnumerateDeviceLayerProperties "
               "terminator.  This means a layer improperly continued.");
    // Should never get here this call isn't dispatched down the chain
    return VK_ERROR_INITIALIZATION_FAILED;
}

VkStringErrorFlags vk_string_validate(const int max_length, const char *utf8) {
    VkStringErrorFlags result = VK_STRING_ERROR_NONE;
    int num_char_bytes = 0;
    int i, j;

    for (i = 0; i <= max_length; i++) {
        if (utf8[i] == 0) {
            break;
        } else if (i == max_length) {
            result |= VK_STRING_ERROR_LENGTH;
            break;
        } else if ((utf8[i] >= 0x20) && (utf8[i] < 0x7f)) {
            num_char_bytes = 0;
        } else if ((utf8[i] & UTF8_ONE_BYTE_MASK) == UTF8_ONE_BYTE_CODE) {
            num_char_bytes = 1;
        } else if ((utf8[i] & UTF8_TWO_BYTE_MASK) == UTF8_TWO_BYTE_CODE) {
            num_char_bytes = 2;
        } else if ((utf8[i] & UTF8_THREE_BYTE_MASK) == UTF8_THREE_BYTE_CODE) {
            num_char_bytes = 3;
        } else {
            result = VK_STRING_ERROR_BAD_DATA;
        }

        // Validate the following num_char_bytes of data
        for (j = 0; (j < num_char_bytes) && (i < max_length); j++) {
            if (++i == max_length) {
                result |= VK_STRING_ERROR_LENGTH;
                break;
            }
            if ((utf8[i] & UTF8_DATA_BYTE_MASK) != UTF8_DATA_BYTE_CODE) {
                result |= VK_STRING_ERROR_BAD_DATA;
            }
        }
    }
    return result;
}