fix: correct utility process exit code on Windows (#50387)

* fix: correct utility process exit code on Windows

On Windows, process exit codes are 32-bit unsigned integers (DWORD).
When passed from Chromium to Electron as a signed int and then
implicitly converted to uint64_t, values with the high bit set
(e.g., NTSTATUS codes) undergo sign extension, producing incorrect
values.

Cast the exit code to uint32_t before widening to uint64_t to
prevent sign extension and preserve the original Windows exit code.

Fixes #49455

Co-authored-by: João Silva <joaomrsilva@tecnico.ulisboa.pt>

* fix: narrow HandleTermination and Shutdown to uint32_t, add tests

Co-authored-by: João Silva <joaomrsilva@tecnico.ulisboa.pt>

---------

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: João Silva <joaomrsilva@tecnico.ulisboa.pt>

shell/browser/api/electron_api_utility_process.cc

@@ -258,7 +258,7 @@ void UtilityProcessWrapper::OnServiceProcessLaunch(
   EmitWithoutEvent("spawn");
 }
 
-void UtilityProcessWrapper::HandleTermination(uint64_t exit_code) {
+void UtilityProcessWrapper::HandleTermination(uint32_t exit_code) {
   // HandleTermination is called from multiple callsites,
   // we need to ensure we only process it for the first callsite.
   if (terminated_)
@@ -326,7 +326,7 @@ void UtilityProcessWrapper::CloseConnectorPort() {
   }
 }
 
-void UtilityProcessWrapper::Shutdown(uint64_t exit_code) {
+void UtilityProcessWrapper::Shutdown(uint32_t exit_code) {
   node_service_remote_.reset();
   HandleTermination(exit_code);
 }

shell/browser/api/electron_api_utility_process.h

@@ -57,7 +57,7 @@ class UtilityProcessWrapper final
   static gin_helper::Handle<UtilityProcessWrapper> Create(gin::Arguments* args);
   static raw_ptr<UtilityProcessWrapper> FromProcessId(base::ProcessId pid);
 
-  void Shutdown(uint64_t exit_code);
+  void Shutdown(uint32_t exit_code);
 
   // gin_helper::Wrappable
   static gin::DeprecatedWrapperInfo kWrapperInfo;
@@ -77,7 +77,7 @@ class UtilityProcessWrapper final
   void OnServiceProcessLaunch(const base::Process& process);
   void CloseConnectorPort();
 
-  void HandleTermination(uint64_t exit_code);
+  void HandleTermination(uint32_t exit_code);
 
   void PostMessage(gin::Arguments* args);
   bool Kill();

spec/api-utility-process-spec.ts

@@ -129,6 +129,22 @@ describe('utilityProcess module', () => {
       expect(code).to.equal(exitCode);
     });
 
+    ifit(process.platform === 'win32')('emits correct exit code when high bit is set on Windows', async () => {
+      // NTSTATUS code with high bit set should not be mangled by sign extension.
+      const exitCode = 0xC0000005;
+      const child = utilityProcess.fork(path.join(fixturesPath, 'custom-exit.js'), [`--exitCode=${exitCode}`]);
+      const [code] = await once(child, 'exit');
+      expect(code).to.equal(exitCode);
+    });
+
+    ifit(process.platform !== 'win32')('emits correct exit code when child process crashes on posix', async () => {
+      // Crash exit codes should not be sign-extended to large 64-bit values.
+      const child = utilityProcess.fork(path.join(fixturesPath, 'crash.js'));
+      const [code] = await once(child, 'exit');
+      expect(code).to.not.equal(0);
+      expect(code).to.be.lessThanOrEqual(0xFFFFFFFF);
+    });
+
     it('does not run JS after process.exit is called', async () => {
       const file = path.join(os.tmpdir(), `no-js-after-exit-log-${Math.random()}`);
       const child = utilityProcess.fork(path.join(fixturesPath, 'no-js-after-exit.js'), [`--testPath=${file}`]);