src: factor out new string arg check

Create a macro that can be used to check the parameters passed into
`NewString` and reused to check the same parameters as passed to
`NewExternalString`

Author: gabrielschulhof

src/js_native_api_v8.cc

@@ -38,6 +38,17 @@
 #define CHECK_NEW_FROM_UTF8(env, result, str)                                  \
   CHECK_NEW_FROM_UTF8_LEN((env), (result), (str), NAPI_AUTO_LENGTH)
 
+#define CHECK_NEW_STRING_ARGS(env, str, length, result)                        \
+  do {                                                                         \
+    CHECK_ENV_NOT_IN_GC((env));                                                \
+    if ((length) > 0) CHECK_ARG((env), (str));                                 \
+    CHECK_ARG((env), (result));                                                \
+    RETURN_STATUS_IF_FALSE(                                                    \
+        (env),                                                                 \
+        ((length) == NAPI_AUTO_LENGTH) || (length) <= INT_MAX,                 \
+        napi_invalid_arg);                                                     \
+  } while (0)
+
 #define CREATE_TYPED_ARRAY(                                                    \
     env, type, size_of_element, buffer, byte_offset, length, out)              \
   do {                                                                         \
@@ -81,12 +92,7 @@ napi_status NewString(napi_env env,
                       size_t length,
                       napi_value* result,
                       StringMaker string_maker) {
-  CHECK_ENV(env);
-  env->CheckGCAccess();
-  if (length > 0) CHECK_ARG(env, str);
-  CHECK_ARG(env, result);
-  RETURN_STATUS_IF_FALSE(
-      env, (length == NAPI_AUTO_LENGTH) || length <= INT_MAX, napi_invalid_arg);
+  CHECK_NEW_STRING_ARGS(env, str, length, result);
 
   auto isolate = env->isolate;
   auto str_maybe = string_maker(isolate);
@@ -105,9 +111,10 @@ napi_status NewExternalString(napi_env env,
                               bool* copied,
                               CreateAPI create_api,
                               StringMaker string_maker) {
+  CHECK_NEW_STRING_ARGS(env, str, length, result);
+
   napi_status status;
 #if defined(V8_ENABLE_SANDBOX)
-  env->CheckGCAccess();
   status = create_api(env, str, length, result);
   if (status == napi_ok) {
     if (copied != nullptr) {