n-api: support type-tagging objects

`napi_instanceof()` is insufficient for reliably establishing the data
type to which a pointer stored with `napi_wrap()` or
`napi_create_external()` inside a JavaScript object points. Thus, we
need a way to "mark" an object with a value that, when later retrieved,
can unambiguously tell us whether it is safe to cast the pointer stored
inside it to a certain structure.

Such a check must survive loading/unloading/multiple instances of an
addon, so we use UUIDs chosen *a priori*.

Fixes: #28164
Co-authored-by: Anna Henningsen <github@addaleax.net>
PR-URL: #28237
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Signed-off-by: Gabriel Schulhof <gabriel.schulhof@intel.com>

benchmark/napi/type-tag-check/binding.gyp

@@ -0,0 +1,8 @@
+{
+  'targets': [
+    {
+      'target_name': 'binding',
+      'sources': [ '../type-tag/binding.c' ]
+    }
+  ]
+}

benchmark/napi/type-tag-check/index.js

@@ -0,0 +1,18 @@
+'use strict';
+const common = require('../../common.js');
+
+let binding;
+try {
+  binding = require(`./build/${common.buildType}/binding`);
+} catch {
+  console.error(`${__filename}: Binding failed to load`);
+  process.exit(0);
+}
+
+const bench = common.createBenchmark(main, {
+  n: [1e5, 1e6, 1e7],
+});
+
+function main({ n }) {
+  binding.checkObjectTag(n, bench, bench.start, bench.end);
+}

benchmark/napi/type-tag/binding.c

@@ -0,0 +1,84 @@
+#include <assert.h>
+#define NAPI_EXPERIMENTAL
+#include <node_api.h>
+
+#define NAPI_CALL(call)                           \
+  do {                                            \
+    napi_status status = call;                    \
+    assert(status == napi_ok && #call " failed"); \
+  } while (0);
+
+#define EXPORT_FUNC(env, exports, name, func)       \
+  do {                                              \
+    napi_value js_func;                             \
+    NAPI_CALL(napi_create_function((env),           \
+                                  (name),           \
+                                  NAPI_AUTO_LENGTH, \
+                                  (func),           \
+                                  NULL,             \
+                                  &js_func));       \
+    NAPI_CALL(napi_set_named_property((env),        \
+                                     (exports),     \
+                                     (name),        \
+                                     js_func));     \
+  } while (0);
+
+static const napi_type_tag tag = {
+  0xe7ecbcd5954842f6, 0x9e75161c9bf27282
+};
+
+static napi_value TagObject(napi_env env, napi_callback_info info) {
+  size_t argc = 4;
+  napi_value argv[4];
+  uint32_t n;
+  uint32_t index;
+  napi_handle_scope scope;
+
+  NAPI_CALL(napi_get_cb_info(env, info, &argc, argv, NULL, NULL));
+  NAPI_CALL(napi_get_value_uint32(env, argv[0], &n));
+  NAPI_CALL(napi_open_handle_scope(env, &scope));
+  napi_value objects[n];
+  for (index = 0; index < n; index++) {
+    NAPI_CALL(napi_create_object(env, &objects[index]));
+  }
+
+  // Time the object tag creation.
+  NAPI_CALL(napi_call_function(env, argv[1], argv[2], 0, NULL, NULL));
+  for (index = 0; index < n; index++) {
+    NAPI_CALL(napi_type_tag_object(env, objects[index], &tag));
+  }
+  NAPI_CALL(napi_call_function(env, argv[1], argv[3], 1, &argv[0], NULL));
+
+  NAPI_CALL(napi_close_handle_scope(env, scope));
+  return NULL;
+}
+
+static napi_value CheckObjectTag(napi_env env, napi_callback_info info) {
+  size_t argc = 4;
+  napi_value argv[4];
+  uint32_t n;
+  uint32_t index;
+  bool is_of_type;
+
+  NAPI_CALL(napi_get_cb_info(env, info, &argc, argv, NULL, NULL));
+  NAPI_CALL(napi_get_value_uint32(env, argv[0], &n));
+  napi_value object;
+  NAPI_CALL(napi_create_object(env, &object));
+  NAPI_CALL(napi_type_tag_object(env, object, &tag));
+
+  // Time the object tag checking.
+  NAPI_CALL(napi_call_function(env, argv[1], argv[2], 0, NULL, NULL));
+  for (index = 0; index < n; index++) {
+    NAPI_CALL(napi_check_object_type_tag(env, object, &tag, &is_of_type));
+    assert(is_of_type && " type mismatch");
+  }
+  NAPI_CALL(napi_call_function(env, argv[1], argv[3], 1, &argv[0], NULL));
+
+  return NULL;
+}
+
+NAPI_MODULE_INIT() {
+  EXPORT_FUNC(env, exports, "tagObject", TagObject);
+  EXPORT_FUNC(env, exports, "checkObjectTag", CheckObjectTag);
+  return exports;
+}

benchmark/napi/type-tag/binding.gyp

@@ -0,0 +1,8 @@
+{
+  'targets': [
+    {
+      'target_name': 'binding',
+      'sources': [ 'binding.c' ]
+    }
+  ]
+}

benchmark/napi/type-tag/check-object-tag.js

@@ -0,0 +1,18 @@
+'use strict';
+const common = require('../../common.js');
+
+let binding;
+try {
+  binding = require(`./build/${common.buildType}/binding`);
+} catch {
+  console.error(`${__filename}: Binding failed to load`);
+  process.exit(0);
+}
+
+const bench = common.createBenchmark(main, {
+  n: [1e5, 1e6, 1e7],
+});
+
+function main({ n }) {
+  binding.checkObjectTag(n, bench, bench.start, bench.end);
+}

benchmark/napi/type-tag/index.js

@@ -0,0 +1,18 @@
+'use strict';
+const common = require('../../common.js');
+
+let binding;
+try {
+  binding = require(`./build/${common.buildType}/binding`);
+} catch {
+  console.error(`${__filename}: Binding failed to load`);
+  process.exit(0);
+}
+
+const bench = common.createBenchmark(main, {
+  n: [1e3, 1e4, 1e5],
+});
+
+function main({ n }) {
+  binding.tagObject(n, bench, bench.start, bench.end);
+}