Remove usage of alloca() & create vk_loader_platform.c

BUILD.gn

@@ -208,13 +208,13 @@ if (!is_android) {
       # "loader/phys_dev_ext.c",
       "loader/settings.c",
       "loader/settings.h",
-      "loader/stack_allocation.h",
       "loader/terminator.c",
       "loader/trampoline.c",
       "loader/unknown_function_handling.h",
       "loader/unknown_function_handling.c",
       "loader/vk_loader_layer.h",
       "loader/vk_loader_platform.h",
+      "loader/vk_loader_platform.c",
       "loader/wsi.c",
       "loader/wsi.h",
     ]

REUSE.toml

@@ -52,6 +52,7 @@ path = [
     "loader/generated/vk_layer_dispatch_table.h",
     "loader/generated/vk_loader_extensions.h",
     "loader/vk_loader_platform.h",
+    "loader/vk_loader_platform.c",
     "scripts/generators/loader_extension_generator.py",
 ]
 precedence = "closest"
@@ -219,7 +220,6 @@ path = [
     "loader/debug_utils.c",
     "loader/loader_windows.h",
     "loader/allocation.h",
-    "loader/stack_allocation.h",
     "loader/loader.h",
     "loader/debug_utils.h",
     "loader/loader_windows.c",

loader/CMakeLists.txt

@@ -51,15 +51,11 @@ if(WIN32)
         configure_file(loader.rc.in ${CMAKE_CURRENT_BINARY_DIR}/loader.rc)
     endif()
 else()
-    # Used to make alloca() and secure_getenv() available
+    # Used to make secure_getenv() available
     target_compile_definitions(loader_specific_options INTERFACE _GNU_SOURCE)
     if(CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
         target_compile_definitions(loader_specific_options INTERFACE __BSD_VISIBLE=1)
     endif()
-    check_include_file("alloca.h" HAVE_ALLOCA_H)
-    if(HAVE_ALLOCA_H)
-        target_compile_definitions(loader_specific_options INTERFACE HAVE_ALLOCA_H)
-    endif()
 
     set(THREADS_PREFER_PTHREAD_FLAG ON)
     find_package(Threads REQUIRED)
@@ -90,6 +86,8 @@ set(NORMAL_LOADER_SRCS
     trampoline.c
     unknown_function_handling.c
     unknown_function_handling.h
+    vk_loader_platform.c
+    vk_loader_platform.h
     wsi.c
     wsi.h
     )

loader/asm_offset.c

@@ -129,7 +129,21 @@ int main(int argc, char **argv) {
         // clang-format on
     };
 
-    FILE *file = loader_fopen("gen_defines.asm", "w");
+    FILE *file = NULL;
+#if defined(_WIN32)
+    errno_t err = fopen_s(&file, "gen_defines.asm", "w");
+    if (err != 0) {
+        fprintf(stderr, "Error: failed to open gen_defines.asm for writing\n");
+        return -1;
+    }
+#else
+    file = fopen("gen_defines.asm", "w");
+    if (NULL == file) {
+        fprintf(stderr, "Error: failed to open gen_defines.asm for writing\n");
+        return -1;
+    }
+#endif
+
     // NOLINTBEGIN(cert-err33-c) - this is a build-time code generator run by developers, not part of the loader's
     // runtime attack surface; a failed write here is immediately visible as a broken build, not worth per-call checks.
     fprintf(file, "\n");