Merge pull request #1173 from streamich/copilot/fix-1172

fix: handle chmod 0 permissions in existsSync and access methods

Author: streamich

src/node/__tests__/volume/chmod-permission-issue.test.ts

@@ -0,0 +1,83 @@
+import { create } from '../../../__tests__/util';
+import { AMODE } from '../../../consts/AMODE';
+
+describe('chmod 0 permission issue reproduction', () => {
+  describe('existsSync()', () => {
+    test('chmod on file and existsSync', () => {
+      // Arrange
+      const vol = create({ '/path/to/file.txt': 'some text' });
+      vol.chmodSync('/path/to/file.txt', 0o0000);
+
+      // Act
+      const exists = vol.existsSync('/path/to/file.txt');
+      const exists2 = vol.existsSync('/path/to/file2.txt');
+      const exists3 = vol.existsSync('/path/to3/file3.txt');
+
+      // Assert
+      expect(exists).toBe(true);
+      expect(exists2).toBe(false);
+      expect(exists3).toBe(false);
+    });
+
+    test('chmod on directory and existsSync', () => {
+      // Arrange
+      const vol = create({ '/path/to/file.txt': 'some text' });
+      vol.chmodSync('/path/to/', 0o0000);
+
+      // Act
+      const exists = vol.existsSync('/path/to/file.txt');
+
+      // Assert
+      expect(exists).toBe(false);
+    });
+  });
+
+  test.each([AMODE.R_OK, AMODE.W_OK])('chmod on file and access mode %d', mode => {
+    // Arrange
+    const vol = create({ '/path/to/file.txt': 'some text' });
+    vol.accessSync('/path/to/file.txt', mode);
+    vol.chmodSync('/path/to/file.txt', 0o0000);
+
+    // Act & Assert
+    expect(() => {
+      vol.accessSync('/path/to/file.txt', mode);
+    }).toThrow();
+  });
+
+  test.each([AMODE.R_OK, AMODE.W_OK])('chmod on directory and access mode %d', mode => {
+    // Arrange
+    const vol = create({ '/path/to/file.txt': 'some text' });
+    vol.accessSync('/path/to/file.txt', mode);
+    vol.chmodSync('/path/to/', 0o0000);
+
+    // Act & Assert
+    expect(() => {
+      vol.accessSync('/path/to/file.txt', mode);
+    }).toThrow();
+  });
+
+  test('chmod on file and access F_OK should not throw', () => {
+    const vol = create({ '/path/to/file.txt': 'some text' });
+    vol.accessSync('/path/to/file.txt', AMODE.F_OK);
+    vol.chmodSync('/path/to/file.txt', 0o0000);
+    vol.accessSync('/path/to/file.txt', AMODE.F_OK);
+  });
+
+  // Test the exact scenario from the issue (https://github.com/streamich/memfs/issues/1172)
+  test('chmod on file and promises access with fs.constants', async () => {
+    const vol = create({ '/path/to/file.txt': 'some text' });
+
+    await vol.promises.chmod('/path/to/file.txt', 0o0000);
+
+    // Should throw for R_OK and W_OK
+    await expect(vol.promises.access('/path/to/file.txt', AMODE.R_OK)).rejects.toThrow();
+    await expect(vol.promises.access('/path/to/file.txt', AMODE.R_OK | AMODE.F_OK)).rejects.toThrow();
+    await expect(vol.promises.access('/path/to/file.txt', AMODE.W_OK)).rejects.toThrow();
+    await expect(vol.promises.access('/path/to/file.txt', AMODE.W_OK | AMODE.F_OK)).rejects.toThrow();
+    await expect(vol.promises.access('/path/to/file.txt', AMODE.W_OK | AMODE.R_OK)).rejects.toThrow();
+    await expect(vol.promises.access('/path/to/file.txt', AMODE.W_OK | AMODE.R_OK | AMODE.F_OK)).rejects.toThrow();
+
+    // F_OK should NOT throw - it just checks existence, which it does exist
+    await expect(vol.promises.access('/path/to/file.txt', AMODE.F_OK)).resolves.toBeUndefined();
+  });
+});

src/node/volume.ts

@@ -74,6 +74,9 @@ const {
   O_DIRECTORY,
   O_SYMLINK,
   F_OK,
+  R_OK,
+  W_OK,
+  X_OK,
   COPYFILE_EXCL,
   COPYFILE_FICLONE_FORCE,
 } = constants;
@@ -896,8 +899,28 @@ export class Volume implements FsCallbackApi, FsSynchronousApi {
   };
 
   private _access(filename: string, mode: number) {
-    // TODO: Need to check mode?
-    this._core.getLinkOrThrow(filename, 'access');
+    const link = this._core.getLinkOrThrow(filename, 'access');
+    const node = link.getNode();
+
+    // F_OK (0) just checks for existence, which we already confirmed above
+    if (mode === F_OK) {
+      return;
+    }
+
+    // Check read permission
+    if (mode & R_OK && !node.canRead()) {
+      throw createError(ERROR_CODE.EACCES, 'access', filename);
+    }
+
+    // Check write permission
+    if (mode & W_OK && !node.canWrite()) {
+      throw createError(ERROR_CODE.EACCES, 'access', filename);
+    }
+
+    // Check execute permission
+    if (mode & X_OK && !node.canExecute()) {
+      throw createError(ERROR_CODE.EACCES, 'access', filename);
+    }
   }
 
   public accessSync = (path: PathLike, mode: number = F_OK) => {