node-api: handle no support for external buffers

Refs: electron/electron#35801
Refs: nodejs/abi-stable-node#441

Electron recently dropped support for external
buffers. Provide a way for addon authors to:
- hide the methods to create external buffers so they can
  avoid using them if they want the broadest compatibility.
- call the methods that create external buffers at runtime
  to check if external buffers are supported and either
  use them or not based on the return code.

Signed-off-by: Michael Dawson <mdawson@devrus.com>

doc/api/n-api.md

@@ -2362,6 +2362,19 @@ This API allocates a JavaScript value with external data attached to it. This
 is used to pass external data through JavaScript code, so it can be retrieved
 later by native code using [`napi_get_value_external`][].
 
+**Some runtimes other than Node.ja hasve dropped support for external buffers**.
+On runtimes other than Node.js this method may return
+`napi_no_external_buffers_allowed` to indicate that external
+buffers are not supported. One such runtime is electron as
+described in this issue
+[electron/issues/35801](https://github.com/electron/electron/issues/35801).
+
+In order to maintain broadest compatibility with all runtimes
+you may define `NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED` in your addon before
+includes for the node-api headers. Doing so will hide the 2 methods
+that create external buffers. This will ensure a compilation error
+occurs if you accidentally use one of these methods.
+
 The API adds a `napi_finalize` callback which will be called when the JavaScript
 object just created is ready for garbage collection. It is similar to
 `napi_wrap()` except that:

src/js_native_api.h

@@ -402,12 +402,14 @@ NAPI_EXTERN napi_status NAPI_CDECL napi_create_arraybuffer(napi_env env,
                                                            void** data,
                                                            napi_value* result);
 NAPI_EXTERN napi_status NAPI_CDECL
+#ifndef NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED
 napi_create_external_arraybuffer(napi_env env,
                                  void* external_data,
                                  size_t byte_length,
                                  napi_finalize finalize_cb,
                                  void* finalize_hint,
                                  napi_value* result);
+#endif  // NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED
 NAPI_EXTERN napi_status NAPI_CDECL napi_get_arraybuffer_info(
     napi_env env, napi_value arraybuffer, void** data, size_t* byte_length);
 NAPI_EXTERN napi_status NAPI_CDECL napi_is_typedarray(napi_env env,

src/js_native_api_types.h

@@ -98,7 +98,8 @@ typedef enum {
   napi_date_expected,
   napi_arraybuffer_expected,
   napi_detachable_arraybuffer_expected,
-  napi_would_deadlock  // unused
+  napi_would_deadlock,  // unused
+  napi_no_external_buffers_allowed
 } napi_status;
 // Note: when adding a new enum value to `napi_status`, please also update
 //   * `const int last_status` in the definition of `napi_get_last_error_info()'

src/node_api.cc

@@ -950,6 +950,10 @@ napi_status NAPI_CDECL napi_create_external_buffer(napi_env env,
   NAPI_PREAMBLE(env);
   CHECK_ARG(env, result);
 
+#if defined(V8_COMPRESS_POINTERS_IN_SHARED_CAGE)
+  return napi_set_last_error(env, napi_no_external_buffers_allowed);
+#endif
+
   v8::Isolate* isolate = env->isolate;
 
   // The finalizer object will delete itself after invoking the callback.

src/node_api.h

@@ -153,13 +153,15 @@ NAPI_EXTERN napi_status NAPI_CDECL napi_create_buffer(napi_env env,
                                                       size_t length,
                                                       void** data,
                                                       napi_value* result);
+#ifndef NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED
 NAPI_EXTERN napi_status NAPI_CDECL
 napi_create_external_buffer(napi_env env,
                             size_t length,
                             void* data,
                             napi_finalize finalize_cb,
                             void* finalize_hint,
                             napi_value* result);
+#endif  // NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED
 NAPI_EXTERN napi_status NAPI_CDECL napi_create_buffer_copy(napi_env env,
                                                            size_t length,
                                                            const void* data,