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 <[email protected]> PR-URL: #45181 Reviewed-By: Chengzhong Wu <[email protected]> Reviewed-By: Minwoo Jung <[email protected]>
nodejs · Jan 3, 2023 · 746175a · 746175a
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diff --git a/doc/api/n-api.md b/doc/api/n-api.md
@@ -579,6 +579,7 @@ typedef enum {
   napi_arraybuffer_expected,
   napi_detachable_arraybuffer_expected,
   napi_would_deadlock,  /* unused */
+  napi_no_external_buffers_allowed
 } napi_status;
 ```
 
@@ -2403,6 +2404,19 @@ napi_create_external_arraybuffer(napi_env env,
 
 Returns `napi_ok` if the API succeeded.
 
+**Some runtimes other than Node.js have 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 functions
+that create external buffers. This will ensure a compilation error
+occurs if you accidentally use one of these methods.
+
 This API returns a Node-API value corresponding to a JavaScript `ArrayBuffer`.
 The underlying byte buffer of the `ArrayBuffer` is externally allocated and
 managed. The caller must ensure that the byte buffer remains valid until the
@@ -2447,6 +2461,19 @@ napi_status napi_create_external_buffer(napi_env env,
 
 Returns `napi_ok` if the API succeeded.
 
+**Some runtimes other than Node.js have 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 functions
+that create external buffers. This will ensure a compilation error
+occurs if you accidentally use one of these methods.
+
 This API allocates a `node::Buffer` object and initializes it with data
 backed by the passed in buffer. While this is still a fully-supported data
 structure, in most cases using a `TypedArray` will suffice.

diff --git a/src/js_native_api.h b/src/js_native_api.h
@@ -401,13 +401,15 @@ NAPI_EXTERN napi_status NAPI_CDECL napi_create_arraybuffer(napi_env env,
                                                            size_t byte_length,
                                                            void** data,
                                                            napi_value* result);
+#ifndef NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED
 NAPI_EXTERN napi_status NAPI_CDECL
 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,

diff --git a/src/js_native_api_types.h b/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()'

diff --git a/src/js_native_api_v8.cc b/src/js_native_api_v8.cc
@@ -746,6 +746,7 @@ static const char* error_messages[] = {
     "An arraybuffer was expected",
     "A detachable arraybuffer was expected",
     "Main thread would deadlock",
+    "External buffers are not allowed",
 };
 
 napi_status NAPI_CDECL napi_get_last_error_info(
@@ -757,7 +758,7 @@ napi_status NAPI_CDECL napi_get_last_error_info(
   // message in the `napi_status` enum each time a new error message is added.
   // We don't have a napi_status_last as this would result in an ABI
   // change each time a message was added.
-  const int last_status = napi_would_deadlock;
+  const int last_status = napi_no_external_buffers_allowed;
 
   static_assert(NAPI_ARRAYSIZE(error_messages) == last_status + 1,
                 "Count of error messages must match count of error values");

diff --git a/src/node_api.cc b/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_ENABLE_SANDBOX)
+  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.

diff --git a/src/node_api.h b/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,

diff --git a/test/js-native-api/test_general/test_general.c b/test/js-native-api/test_general/test_general.c
@@ -1,3 +1,8 @@
+// we define NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED here to
+// validate that it can be used as a form of test itself. It is
+// not related to any of the other tests
+// defined in the file
+#define NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>

diff --git a/test/node-api/test_general/test_general.c b/test/node-api/test_general/test_general.c
@@ -1,4 +1,9 @@
 #define NAPI_EXPERIMENTAL
+// we define NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED here to validate that it can
+// be used as a form of test itself. It is
+// not related to any of the other tests
+// defined in the file
+#define NODE_API_NO_EXTERNAL_BUFFERS_ALLOWED
 #include <node_api.h>
 #include <stdlib.h>
 #include "../../js-native-api/common.h"