fs: cancel in-flight stat on abort

lib/fs.js

@@ -392,6 +392,7 @@ function bindSignalToReq(req, signal, callback) {
   let aborted = false;
   const onAbort = () => {
     aborted = true;
+    req.cancel();
     callback(new AbortError(undefined, { cause: signal.reason }));
   };
   kResistStopPropagation ??= require('internal/event_target').kResistStopPropagation;

src/node_file.cc

@@ -758,6 +758,12 @@ void NewFSReqCallback(const FunctionCallbackInfo<Value>& args) {
   new FSReqCallback(binding_data, args.This(), args[0]->IsTrue());
 }
 
+void CancelFSReq(const FunctionCallbackInfo<Value>& args) {
+  FSReqBase* req_wrap;
+  ASSIGN_OR_RETURN_UNWRAP(&req_wrap, args.This());
+  req_wrap->Cancel();
+}
+
 FSReqAfterScope::FSReqAfterScope(FSReqBase* wrap, uv_fs_t* req)
     : wrap_(wrap),
       req_(req),
@@ -4618,6 +4624,7 @@ static void CreatePerIsolateProperties(IsolateData* isolate_data,
   fst->InstanceTemplate()->SetInternalFieldCount(
       FSReqBase::kInternalFieldCount);
   fst->Inherit(AsyncWrap::GetConstructorTemplate(isolate_data));
+  SetProtoMethod(isolate, fst, "cancel", CancelFSReq);
   SetConstructorFunction(isolate, target, "FSReqCallback", fst);
 
   // Create FunctionTemplate for FileHandleReadWrap. There’s no need
@@ -4734,6 +4741,7 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
   registry->Register(HandleToFd);
 #endif
   registry->Register(NewFSReqCallback);
+  registry->Register(CancelFSReq);
 
   registry->Register(FileHandle::New);
   registry->Register(FileHandle::Close);

test/parallel/test-fs-stat-cancel-inflight.js

@@ -0,0 +1,37 @@
+'use strict';
+
+// Aborting a queued stat must cancel the libuv request instead of running it.
+// The threadpool is saturated so the request is still queued when it is
+// cancelled; the queue is FIFO, so the stat cannot start before the blocker.
+
+const common = require('../common');
+
+if (!common.hasCrypto) common.skip('missing crypto');
+
+const assert = require('assert');
+const crypto = require('crypto');
+const { spawnSync } = require('child_process');
+
+if (process.argv[2] !== 'child') {
+  const result = spawnSync(
+    process.execPath,
+    ['--expose-internals', __filename, 'child'],
+    { env: { ...process.env, UV_THREADPOOL_SIZE: '1' }, encoding: 'utf8' },
+  );
+  assert.strictEqual(result.status, 0, result.stderr);
+  return;
+}
+
+const { internalBinding } = require('internal/test/binding');
+const binding = internalBinding('fs');
+
+// Occupy the only worker thread so the stat below cannot start.
+crypto.pbkdf2('secret', 'salt', 500_000, 32, 'sha512', common.mustCall());
+
+const req = new binding.FSReqCallback(false);
+req.oncomplete = common.mustCall((err) => {
+  // Without cancellation the stat would run and report success.
+  assert.strictEqual(err?.code, 'ECANCELED');
+});
+binding.stat(__filename, false, req, true);
+req.cancel();