fix(cli): keep unix socket path within OS length limit

packages/utils/fileUtils.ts

@@ -113,7 +113,13 @@ export function makeSocketPath(domain: string, name: string): string {
   }
   const baseDir = process.env.PLAYWRIGHT_SOCKETS_DIR || path.join(os.tmpdir(), `pw-${userNameHash}`);
   const dir = path.join(baseDir, domain);
-  const result = path.join(dir, `${name}.sock`);
   fs.mkdirSync(dir, { recursive: true });
+  let result = path.join(dir, `${name}.sock`);
+  // sockaddr_un.sun_path caps unix socket paths at 104 bytes on macOS/BSD and
+  // 108 on Linux. A longer path fails with EINVAL or binds to a truncated
+  // path, so fall back to a hashed name to stay within the limit.
+  const maxSocketPathLength = process.platform === 'linux' ? 107 : 103;
+  if (Buffer.byteLength(result) > maxSocketPathLength)
+    result = path.join(dir, `${calculateSha1(name).slice(0, 16)}.sock`);
   return result;
 }

tests/library/unit/socket-path.spec.ts

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { test as it, expect } from '@playwright/test';
+import fs from 'fs';
+import net from 'net';
+import { makeSocketPath } from '../../../packages/utils/fileUtils';
+
+it.describe('makeSocketPath', () => {
+  it.skip(process.platform === 'win32', 'Windows named pipes are not constrained by sockaddr_un.sun_path');
+
+  it('should keep a long socket name within the OS path length limit', () => {
+    const socketPath = makeSocketPath('cli', 'session-' + 'a'.repeat(200));
+    // sockaddr_un.sun_path holds 104 bytes on macOS/BSD and 108 on Linux.
+    const limit = process.platform === 'linux' ? 107 : 103;
+    expect(Buffer.byteLength(socketPath)).toBeLessThanOrEqual(limit);
+    expect(socketPath.endsWith('.sock')).toBe(true);
+  });
+
+  it('should produce a listenable socket path for a long name', async () => {
+    const socketPath = makeSocketPath('cli', 'listen-' + 'b'.repeat(200));
+    const server = net.createServer();
+    try {
+      await new Promise<void>((resolve, reject) => {
+        server.on('error', reject);
+        server.listen(socketPath, resolve);
+      });
+      // The socket must exist at exactly the returned path; a path over the
+      // limit would silently bind to a truncated one and break clients.
+      expect(fs.existsSync(socketPath)).toBe(true);
+    } finally {
+      await new Promise<void>(resolve => server.close(() => resolve()));
+      fs.rmSync(socketPath, { force: true });
+    }
+  });
+
+  it('should keep short socket names human-readable', () => {
+    expect(makeSocketPath('cli', 'default').endsWith('default.sock')).toBe(true);
+  });
+});