[hooks_runner] Fix Windows executable handling in runProcess

pkgs/hooks_runner/lib/src/utils/run_process.dart

@@ -4,7 +4,8 @@
 
 import 'dart:async';
 import 'dart:developer';
-import 'dart:io' show Process, ProcessException, ProcessResult, systemEncoding;
+import 'dart:io'
+    show Platform, Process, ProcessException, ProcessResult, systemEncoding;
 
 import 'package:file/file.dart';
 import 'package:logging/logging.dart';
@@ -58,11 +59,21 @@ Future<RunProcessResult> runProcess({
       workingDirectory: workingDirectory?.toFilePath(),
       environment: environment,
       includeParentEnvironment: includeParentEnvironment,
-      // Never run through a shell. On Windows, running an executable through
-      // `cmd.exe /c` mangles the command line when more than one argument is
-      // quoted (cmd strips the outer quotes when the line contains more than
-      // two quote characters), which breaks any invocation whose executable
-      // and arguments contain spaces.
+      // On Windows, only launch through `cmd.exe` when strictly necessary.
+      //
+      // `CreateProcess` (used when `runInShell` is `false`) can directly launch
+      // `.exe`/`.com` executables and applies the correct command-line quoting,
+      // so we avoid the shell for those: running them through `cmd.exe /c`
+      // mangles the command line when more than one argument is quoted (cmd
+      // strips the outer quotes when the line contains more than two quote
+      // characters), which breaks any invocation whose executable and arguments
+      // contain spaces.
+      //
+      // However, `CreateProcess` cannot resolve a bare command name to a
+      // `.bat`/`.cmd` shim via `PATHEXT`, nor execute such a shim directly (for
+      // example the executables generated by `dart install`). Those must go
+      // through `cmd.exe`, so we opt into the shell for them.
+      runInShell: Platform.isWindows && _needsShellOnWindows(executable),
     );
 
     final stdoutSub = process.stdout.listen((List<int> data) {
@@ -117,6 +128,24 @@ Future<RunProcessResult> runProcess({
   }
 }
 
+/// Whether [executable] must be launched through `cmd.exe` on Windows.
+///
+/// `CreateProcess` can only directly launch `.exe`/`.com` binaries. Anything
+/// else (a `.bat`/`.cmd` shim, or a bare command name that resolves to one via
+/// `PATHEXT`) has to be run through the shell.
+bool _needsShellOnWindows(Uri executable) {
+  final path = executable.toFilePath();
+  final lastSeparator = path.lastIndexOf(RegExp(r'[\\/]'));
+  final fileName = lastSeparator == -1
+      ? path
+      : path.substring(lastSeparator + 1);
+  final dot = fileName.lastIndexOf('.');
+  // No extension (e.g. a bare command name resolved via `PATHEXT`).
+  if (dot <= 0) return true;
+  final extension = fileName.substring(dot).toLowerCase();
+  return extension != '.exe' && extension != '.com';
+}
+
 /// Drop in replacement of [ProcessResult].
 class RunProcessResult {
   final int pid;

pkgs/hooks_runner/test/utils/run_process_test.dart

@@ -6,12 +6,11 @@
 // contain a space (e.g. the default pub cache under a Windows user name with
 // a space, `C:\Users\First Last\AppData\Local\Pub\Cache\...`).
 //
-// On Windows, `runProcess` runs through `cmd.exe` (`runInShell`) whenever a
-// `workingDirectory` is passed. `cmd.exe`'s `/c` quote-stripping rule mangles
-// the command line as soon as more than one token needs quoting because it
-// contains a space (the executable path and an argument, or two arguments),
-// causing errors like
-// `'C:\Program' is not recognized as an internal or external command`.
+// On Windows, `runProcess` only runs through `cmd.exe` (`runInShell`) when
+// strictly necessary: bare command names (resolved via `PATHEXT`) and
+// `.bat`/`.cmd` shims. For `.exe`/`.com` binaries it uses `CreateProcess`
+// directly so command lines with multiple quoted tokens are not mangled by
+// `cmd.exe`'s `/c` quote-stripping rule.
 
 import 'dart:io';
 
@@ -78,6 +77,55 @@ void main(List<String> args) {
     expect(result.stdout, contains('ARGV:first arg|second arg'));
   });
 
+  test(
+    'runProcess runs bare .bat shim from working directory on Windows',
+    () async {
+      if (!Platform.isWindows) return;
+
+      final binDir = await tempDirForTest();
+      final batUri = binDir.resolve('test shim.bat');
+      await File.fromUri(batUri).writeAsString(
+        '@echo off\r\necho SHIM_OK %*\r\n',
+      );
+
+      final result = await runProcess(
+        executable: Uri.parse('test shim'),
+        arguments: ['--help'],
+        workingDirectory: binDir,
+        logger: logger,
+      );
+
+      expect(result.exitCode, 0);
+      expect(result.stdout, contains('SHIM_OK'));
+      expect(result.stdout, contains('--help'));
+    },
+  );
+
+  test(
+    'runProcess runs bare .bat shim from PATH on Windows',
+    () async {
+      if (!Platform.isWindows) return;
+
+      final binDir = await tempDirForTest();
+      final batUri = binDir.resolve('test shim.bat');
+      await File.fromUri(batUri).writeAsString(
+        '@echo off\r\necho SHIM_OK %*\r\n',
+      );
+
+      final originalPath = Platform.environment['PATH'] ?? '';
+      final result = await runProcess(
+        executable: Uri.parse('test shim'),
+        arguments: ['--help'],
+        environment: {'PATH': '${binDir.toFilePath()};$originalPath'},
+        logger: logger,
+      );
+
+      expect(result.exitCode, 0);
+      expect(result.stdout, contains('SHIM_OK'));
+      expect(result.stdout, contains('--help'));
+    },
+  );
+
   test('runProcess handles arguments containing a space and quotes', () async {
     final workingDir = await tempDirForTest();
     final result = await runProcess(