Various checks for binary lua files (#397)

* various checks for binary lua files

* endianness

src/pc/lua/smlua.c

@@ -64,7 +64,111 @@ void smlua_exec_str(char* str) {
     lua_pop(L, lua_gettop(L));
 }
 
+#define LUA_BOM_11 0x0000000000005678llu
+#define LUA_BOM_19 0x4077280000000000llu
+
+static bool smlua_check_binary_header(struct ModFile *file) {
+    FILE *f = fopen(file->cachedPath, "rb");
+    if (f) {
+
+        // Read signature
+        char signature[sizeof(LUA_SIGNATURE)] = {0};
+        if (fread(signature, 1, sizeof(LUA_SIGNATURE) - 1, f) != sizeof(LUA_SIGNATURE) - 1) {
+            LOG_LUA("Failed to load lua script '%s': File too short.", file->cachedPath);
+            fclose(f);
+            return false;
+        }
+
+        // Check signature
+        if (strcmp(signature, LUA_SIGNATURE) != 0) {
+            fclose(f);
+            return true; // Not a binary lua
+        }
+
+        // Read version number
+        u8 version;
+        if (fread(&version, 1, 1, f) != 1) {
+            LOG_LUA("Failed to load lua script '%s': File too short.", file->cachedPath);
+            fclose(f);
+            return false;
+        }
+
+        // Check version number
+        u8 expectedVersion = strtoul(LUA_VERSION_MAJOR LUA_VERSION_MINOR, NULL, 16);
+        if (version != expectedVersion) {
+            LOG_LUA("Failed to load lua script '%s': Lua versions don't match (%X, expected %X).", file->cachedPath, version, expectedVersion);
+            fclose(f);
+            return false;
+        }
+
+        // Read the rest of the header
+        u8 header[28];
+        if (fread(header, 1, 28, f) != 28) {
+            LOG_LUA("Failed to load lua script '%s': File too short.", file->cachedPath);
+            fclose(f);
+            return false;
+        }
+
+        // The following errors are silent (they're due to non-matching endianness/bitness and shouldn't prevent the rest of the mod from loading)
+
+        // Check endianness
+        u64 bom11 = *((u64 *) (header + 12));
+        u64 bom19 = *((u64 *) (header + 20));
+        if (bom11 != LUA_BOM_11) {
+            LOG_ERROR("Failed to load lua script '%s': BOM at offset 0x11 don't match (%016llX, expected %016llX).", file->cachedPath, bom11, LUA_BOM_11);
+            fclose(f);
+            return false;
+        }
+        if (bom19 != LUA_BOM_19) {
+            LOG_ERROR("Failed to load lua script '%s': BOM at offset 0x19 don't match (%016llX, expected %016llX).", file->cachedPath, bom19, LUA_BOM_19);
+            fclose(f);
+            return false;
+        }
+
+        // Check sizes
+        u8 sizeOfCInteger = header[7];
+        u8 sizeOfCPointer = header[8];
+        u8 sizeOfCFloat = header[9];
+        u8 sizeOfLuaInteger = header[10];
+        u8 sizeOfLuaNumber = header[11];
+        if (sizeOfCInteger != sizeof(int)) {
+            LOG_ERROR("Failed to load lua script '%s': sizes of C Integer don't match (%d, expected %llu).", file->cachedPath, sizeOfCInteger, sizeof(int));
+            fclose(f);
+            return false;
+        }
+        if (sizeOfCPointer != sizeof(void *)) { // 4 for 32-bit architectures, 8 for 64-bit
+            LOG_ERROR("Failed to load lua script '%s': sizes of C Pointer don't match (%d, expected %llu).", file->cachedPath, sizeOfCPointer, sizeof(void *));
+            fclose(f);
+            return false;
+        }
+        if (sizeOfCFloat != sizeof(float)) {
+            LOG_ERROR("Failed to load lua script '%s': sizes of C Float don't match (%d, expected %llu).", file->cachedPath, sizeOfCFloat, sizeof(float));
+            fclose(f);
+            return false;
+        }
+        if (sizeOfLuaInteger != sizeof(LUA_INTEGER)) {
+            LOG_ERROR("Failed to load lua script '%s': sizes of Lua Integer don't match (%d, expected %llu).", file->cachedPath, sizeOfLuaInteger, sizeof(LUA_INTEGER));
+            fclose(f);
+            return false;
+        }
+        if (sizeOfLuaNumber != sizeof(LUA_NUMBER)) {
+            LOG_ERROR("Failed to load lua script '%s': sizes of Lua Number don't match (%d, expected %llu).", file->cachedPath, sizeOfLuaNumber, sizeof(LUA_NUMBER));
+            fclose(f);
+            return false;
+        }
+
+        // All's good
+        LOG_INFO("Loading lua script '%s'", file->cachedPath);
+        fclose(f);
+        return true;
+    }
+    LOG_LUA("Failed to load lua script '%s': File not found.", file->cachedPath);
+    return false;
+}
+
 static void smlua_load_script(struct Mod* mod, struct ModFile* file, u16 remoteIndex) {
+    if (!smlua_check_binary_header(file)) return;
+
     lua_State* L = gLuaState;
 
     lua_settop(L, 0);