src,test: add V8 API to test the hash seed

Author: targos

Makefile

@@ -654,10 +654,6 @@ test-internet: all ## Run internet tests.
 test-tick-processor: all ## Run tick processor tests.
 	$(PYTHON) tools/test.py $(PARALLEL_ARGS) tick-processor
 
-.PHONY: test-hash-seed
-test-hash-seed: all ## Verifu that the hash seed used by V8 for hashing is random.
-	$(NODE) test/pummel/test-hash-seed.js
-
 .PHONY: test-doc
 test-doc: doc-only lint-md ## Build, lint, and verify the docs.
 	@if [ "$(shell $(node_use_openssl_and_icu))" != "true" ]; then \
@@ -751,8 +747,6 @@ test-v8: v8  ## Run the V8 test suite on deps/v8.
 				mjsunit cctest debugger inspector message preparser \
 				$(TAP_V8)
 	$(call convert_to_junit,$(TAP_V8_JSON))
-	$(info Testing hash seed)
-	$(MAKE) test-hash-seed
 
 test-v8-intl: v8 ## Run the v8 test suite, intl tests.
 	export PATH="$(NO_BIN_OVERRIDE_PATH)" && \

src/node_v8.cc

@@ -32,6 +32,7 @@
 namespace node {
 namespace v8_utils {
 using v8::Array;
+using v8::BigInt;
 using v8::Context;
 using v8::FunctionCallbackInfo;
 using v8::FunctionTemplate;
@@ -238,6 +239,12 @@ void SetFlagsFromString(const FunctionCallbackInfo<Value>& args) {
   V8::SetFlagsFromString(*flags, static_cast<size_t>(flags.length()));
 }
 
+void GetHashSeed(const FunctionCallbackInfo<Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  uint64_t hash_seed = isolate->GetHashSeed();
+  args.GetReturnValue().Set(BigInt::NewFromUnsigned(isolate, hash_seed));
+}
+
 static const char* GetGCTypeName(v8::GCType gc_type) {
   switch (gc_type) {
     case v8::GCType::kGCTypeScavenge:
@@ -478,6 +485,8 @@ void Initialize(Local<Object> target,
   // Export symbols used by v8.setFlagsFromString()
   SetMethod(context, target, "setFlagsFromString", SetFlagsFromString);
 
+  SetMethod(context, target, "getHashSeed", GetHashSeed);
+
   // GCProfiler
   Local<FunctionTemplate> t =
       NewFunctionTemplate(env->isolate(), GCProfiler::New);
@@ -493,6 +502,7 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
   registry->Register(UpdateHeapCodeStatisticsBuffer);
   registry->Register(UpdateHeapSpaceStatisticsBuffer);
   registry->Register(SetFlagsFromString);
+  registry->Register(GetHashSeed);
   registry->Register(SetHeapSnapshotNearHeapLimit);
   registry->Register(GCProfiler::New);
   registry->Register(GCProfiler::Start);

test/fixtures/guess-hash-seed.js

@@ -0,0 +1,27 @@
+import assert from 'node:assert';
+import { execFile } from 'node:child_process';
+import { promisify, debuglog } from 'node:util';
+
+import '../common/index.mjs';
+
+// This test verifies that the V8 hash seed is random
+// and unique between child processes.
+
+const execFilePromise = promisify(execFile);
+const debug = debuglog('test');
+
+const kRepetitions = 3;
+
+const seeds = await Promise.all(Array.from({ length: kRepetitions }, generateSeed));
+debug(`Seeds: ${seeds}`);
+assert.strictEqual(new Set(seeds).size, seeds.length);
+assert.strictEqual(seeds.length, kRepetitions);
+
+async function generateSeed() {
+  const output = await execFilePromise(process.execPath, [
+    '--expose-internals',
+    '--print',
+    'require("internal/test/binding").internalBinding("v8").getHashSeed()'
+  ]);
+  return output.stdout.trim();
+}