loader: Dynamically load Win8+ functions

Allow loader to run on Windows 7 by dynamically loading function
pointers for Windows 8 and above APIs.

3 files changed, 22 insertions, 16 deletions

diff --git a/loader/loader.c b/loader/loader.c
index 8b73343e1..f41d460f8 100644
--- a/loader/loader.c
+++ b/loader/loader.c
@@ -2911,9 +2911,7 @@ static VkResult read_data_files_in_search_paths(const struct loader_instance *in
 #endif
 
 #if defined(_WIN32)
-#if WINVER >= _WIN32_WINNT_WINBLUE
     char *package_path = NULL;
-#endif
 #else
     // Determine how much space is needed to generate the full search path
     // for the current manifest files.
@@ -3001,7 +2999,7 @@ static VkResult read_data_files_in_search_paths(const struct loader_instance *in
             }
             additional_env = loader_secure_getenv(VK_ADDITIONAL_DRIVER_FILES_ENV_VAR, inst);
             relative_location = VK_DRIVERS_INFO_RELATIVE_DIR;
-#if defined(_WIN32) && WINVER >= _WIN32_WINNT_WINBLUE
+#if defined(_WIN32)
             package_path = windows_get_app_package_manifest_path(inst);
 #endif
             break;
@@ -3035,7 +3033,7 @@ static VkResult read_data_files_in_search_paths(const struct loader_instance *in
         // Add the size of any additional search paths defined in the additive environment variable
         if (NULL != additional_env) {
             search_path_size += determine_data_file_path_size(additional_env, 0) + 2;
-#if defined(_WIN32) && WINVER >= _WIN32_WINNT_WINBLUE
+#if defined(_WIN32)
         }
         if (NULL != package_path) {
             search_path_size += determine_data_file_path_size(package_path, 0) + 2;
@@ -3092,7 +3090,7 @@ static VkResult read_data_files_in_search_paths(const struct loader_instance *in
             copy_data_file_info(additional_env, NULL, 0, &cur_path_ptr);
         }
 
-#if defined(_WIN32) && WINVER >= _WIN32_WINNT_WINBLUE
+#if defined(_WIN32)
         if (NULL != package_path) {
             copy_data_file_info(package_path, NULL, 0, &cur_path_ptr);
         }
@@ -3231,7 +3229,7 @@ out:
     if (NULL != override_env) {
         loader_free_getenv(override_env, inst);
     }
-#if defined(_WIN32) && WINVER >= _WIN32_WINNT_WINBLUE
+#if defined(_WIN32)
     if (NULL != package_path) {
         loader_instance_heap_free(inst, package_path);
     }
diff --git a/loader/loader_windows.c b/loader/loader_windows.c
index f99d05df9..89408d2ed 100644
--- a/loader/loader_windows.c
+++ b/loader/loader_windows.c
@@ -51,9 +51,7 @@
 #include <dxgi1_6.h>
 #include "adapters.h"
 
-#if WINVER >= _WIN32_WINNT_WINBLUE
 #include <appmodel.h>
-#endif
 
 #if !defined(NDEBUG)
 #include <crtdbg.h>
@@ -1000,15 +998,28 @@ VkResult windows_sort_physical_device_groups(struct loader_instance *inst, const
     return VK_SUCCESS;
 }
 
-#if WINVER >= _WIN32_WINNT_WINBLUE
 char *windows_get_app_package_manifest_path(const struct loader_instance *inst) {
+    // These functions are only available on Windows 8 and above, load them dynamically for compatibility with Windows 7
+    typedef LONG(WINAPI * PFN_GetPackagesByPackageFamily)(PCWSTR, UINT32 *, PWSTR *, UINT32 *, WCHAR *);
+    PFN_GetPackagesByPackageFamily fpGetPackagesByPackageFamily =
+        (PFN_GetPackagesByPackageFamily)GetProcAddress(GetModuleHandle(TEXT("kernel32.dll")), "GetPackagesByPackageFamily");
+    if (!fpGetPackagesByPackageFamily) {
+        return NULL;
+    }
+    typedef LONG(WINAPI * PFN_GetPackagePathByFullName)(PCWSTR, UINT32 *, PWSTR);
+    PFN_GetPackagePathByFullName fpGetPackagePathByFullName =
+        (PFN_GetPackagePathByFullName)GetProcAddress(GetModuleHandle(TEXT("kernel32.dll")), "GetPackagePathByFullName");
+    if (!fpGetPackagePathByFullName) {
+        return NULL;
+    }
+
     UINT32 numPackages = 0, bufferLength = 0;
     /* This literal string identifies the Microsoft-published OpenCL and OpenGL Compatibility Pack
      * (so named at the time this is being added), which contains OpenGLOn12 and OpenCLOn12 mapping
      * layers, and will contain VulkanOn12 (aka Dozen) going forward.
      */
     PCWSTR familyName = L"Microsoft.D3DMappingLayers_8wekyb3d8bbwe";
-    if (ERROR_INSUFFICIENT_BUFFER != GetPackagesByPackageFamily(familyName, &numPackages, NULL, &bufferLength, NULL) ||
+    if (ERROR_INSUFFICIENT_BUFFER != fpGetPackagesByPackageFamily(familyName, &numPackages, NULL, &bufferLength, NULL) ||
         numPackages == 0 || bufferLength == 0) {
         loader_log(inst, VULKAN_LOADER_INFO_BIT, 0,
                    "windows_get_app_package_manifest_path: Failed to find mapping layers packages by family name\n");
@@ -1024,7 +1035,7 @@ char *windows_get_app_package_manifest_path(const struct loader_instance *inst)
         goto cleanup;
     }
 
-    if (ERROR_SUCCESS != GetPackagesByPackageFamily(familyName, &numPackages, packages, &bufferLength, buffer)) {
+    if (ERROR_SUCCESS != fpGetPackagesByPackageFamily(familyName, &numPackages, packages, &bufferLength, buffer)) {
         loader_log(inst, VULKAN_LOADER_ERROR_BIT, 0,
                    "windows_get_app_package_manifest_path: Failed to mapping layers package full names\n");
         goto cleanup;
@@ -1033,8 +1044,8 @@ char *windows_get_app_package_manifest_path(const struct loader_instance *inst)
     UINT32 pathLength = 0;
     WCHAR path[MAX_PATH];
     memset(path, 0, sizeof(path));
-    if (ERROR_INSUFFICIENT_BUFFER != GetPackagePathByFullName(packages[0], &pathLength, NULL) || pathLength > MAX_PATH ||
-        ERROR_SUCCESS != GetPackagePathByFullName(packages[0], &pathLength, path)) {
+    if (ERROR_INSUFFICIENT_BUFFER != fpGetPackagePathByFullName(packages[0], &pathLength, NULL) || pathLength > MAX_PATH ||
+        ERROR_SUCCESS != fpGetPackagePathByFullName(packages[0], &pathLength, path)) {
         loader_log(inst, VULKAN_LOADER_ERROR_BIT, 0,
                    "windows_get_app_package_manifest_path: Failed to get mapping layers package path\n");
         goto cleanup;
@@ -1061,5 +1072,4 @@ cleanup:
     loader_instance_heap_free(inst, packages);
     return ret;
 }
-#endif
 #endif  // _WIN32
diff --git a/loader/loader_windows.h b/loader/loader_windows.h
index f1c6fbb1e..80ba6ebe1 100644
--- a/loader/loader_windows.h
+++ b/loader/loader_windows.h
@@ -113,9 +113,7 @@ VkResult windows_sort_physical_device_groups(struct loader_instance *inst, const
 // Returns VkLoaderFeatureFlags containing VK_LOADER_FEATURE_PHYSICAL_DEVICE_SORTING if successful, otherwise 0
 VkLoaderFeatureFlags windows_initialize_dxgi(void);
 
-#if WINVER >= _WIN32_WINNT_WINBLUE  // Only Available on windows 8 and above
 // Retrieve a path to an installed app package that contains Vulkan manifests.
 // When done using the returned string, the caller should free the pointer.
 char *windows_get_app_package_manifest_path(const struct loader_instance *inst);
-#endif
 #endif  // WIN32