refactor(core): centralize path validation and allow temp dir access for tools (#17185)

Co-authored-by: Your Name <joshualitt@google.com>

packages/core/src/tools/write-file.test.ts

@@ -28,6 +28,7 @@ import type { Config } from '../config/config.js';
 import { ApprovalMode } from '../policy/types.js';
 import type { ToolRegistry } from './tool-registry.js';
 import path from 'node:path';
+import { isSubpath } from '../utils/paths.js';
 import fs from 'node:fs';
 import os from 'node:os';
 import { GeminiClient } from '../core/client.js';
@@ -59,6 +60,7 @@ vi.mock('../ide/ide-client.js', () => ({
 }));
 let mockGeminiClientInstance: Mocked<GeminiClient>;
 let mockBaseLlmClientInstance: Mocked<BaseLlmClient>;
+let mockConfig: Config;
 const mockEnsureCorrectEdit = vi.fn<typeof ensureCorrectEdit>();
 const mockEnsureCorrectFileContent = vi.fn<typeof ensureCorrectFileContent>();
 const mockIdeClient = {
@@ -108,8 +110,10 @@ const mockConfigInternal = {
     }) as unknown as ToolRegistry,
   isInteractive: () => false,
   getDisableLLMCorrection: vi.fn(() => true),
+  storage: {
+    getProjectTempDir: vi.fn().mockReturnValue('/tmp/project'),
+  },
 };
-const mockConfig = mockConfigInternal as unknown as Config;
 
 vi.mock('../telemetry/loggers.js', () => ({
   logFileOperation: vi.fn(),
@@ -135,6 +139,35 @@ describe('WriteFileTool', () => {
       fs.mkdirSync(plansDir, { recursive: true });
     }
 
+    const workspaceContext = new WorkspaceContext(rootDir, [plansDir]);
+    const mockStorage = {
+      getProjectTempDir: vi.fn().mockReturnValue('/tmp/project'),
+    };
+
+    mockConfig = {
+      ...mockConfigInternal,
+      getWorkspaceContext: () => workspaceContext,
+      storage: mockStorage,
+      isPathAllowed(this: Config, absolutePath: string): boolean {
+        const workspaceContext = this.getWorkspaceContext();
+        if (workspaceContext.isPathWithinWorkspace(absolutePath)) {
+          return true;
+        }
+
+        const projectTempDir = this.storage.getProjectTempDir();
+        return isSubpath(path.resolve(projectTempDir), absolutePath);
+      },
+      validatePathAccess(this: Config, absolutePath: string): string | null {
+        if (this.isPathAllowed(absolutePath)) {
+          return null;
+        }
+
+        const workspaceDirs = this.getWorkspaceContext().getDirectories();
+        const projectTempDir = this.storage.getProjectTempDir();
+        return `Path not in workspace: Attempted path "${absolutePath}" resolves outside the allowed workspace directories: ${workspaceDirs.join(', ')} or the project temp directory: ${projectTempDir}`;
+      },
+    } as unknown as Config;
+
     // Setup GeminiClient mock
     mockGeminiClientInstance = new (vi.mocked(GeminiClient))(
       mockConfig,
@@ -243,9 +276,7 @@ describe('WriteFileTool', () => {
         file_path: outsidePath,
         content: 'hello',
       };
-      expect(() => tool.build(params)).toThrow(
-        /File path must be within one of the workspace directories/,
-      );
+      expect(() => tool.build(params)).toThrow(/Path not in workspace/);
     });
 
     it('should throw an error if path is a directory', () => {
@@ -816,9 +847,7 @@ describe('WriteFileTool', () => {
         file_path: '/etc/passwd',
         content: 'malicious',
       };
-      expect(() => tool.build(params)).toThrow(
-        /File path must be within one of the workspace directories/,
-      );
+      expect(() => tool.build(params)).toThrow(/Path not in workspace/);
     });
 
     it('should allow paths within the plans directory', () => {
@@ -834,9 +863,7 @@ describe('WriteFileTool', () => {
         file_path: path.join(plansDir, '..', 'escaped.txt'),
         content: 'malicious',
       };
-      expect(() => tool.build(params)).toThrow(
-        /File path must be within one of the workspace directories/,
-      );
+      expect(() => tool.build(params)).toThrow(/Path not in workspace/);
     });
   });
 
@@ -874,7 +901,6 @@ describe('WriteFileTool', () => {
         errorMessage: 'Generic write error',
         expectedMessagePrefix: 'Error writing to file',
         mockFsExistsSync: false,
-        restoreAllMocks: true,
       },
     ])(
       'should return $errorType error when write fails with $errorCode',
@@ -884,25 +910,22 @@ describe('WriteFileTool', () => {
         errorMessage,
         expectedMessagePrefix,
         mockFsExistsSync,
-        restoreAllMocks,
       }) => {
         const filePath = path.join(rootDir, `${errorType}_file.txt`);
         const content = 'test content';
 
-        if (restoreAllMocks) {
-          vi.restoreAllMocks();
-        }
-
-        // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        let existsSyncSpy: any;
+        let existsSyncSpy: // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        ReturnType<typeof vi.spyOn<any, 'existsSync'>> | undefined = undefined;
 
         try {
           if (mockFsExistsSync) {
             const originalExistsSync = fs.existsSync;
             existsSyncSpy = vi
-              .spyOn(fs, 'existsSync')
-              .mockImplementation((path) =>
-                path === filePath ? false : originalExistsSync(path as string),
+              // eslint-disable-next-line @typescript-eslint/no-explicit-any
+              .spyOn(fs as any, 'existsSync')
+              // eslint-disable-next-line @typescript-eslint/no-explicit-any
+              .mockImplementation((path: any) =>
+                path === filePath ? false : originalExistsSync(path),
               );
           }