Switch fuzz task to UTaskLocalExecutor and improve fuzzer setup robustness.

- Change `fuzz` task type to `UTaskLocalExecutor` in `task_types.py` to run fuzz tasks locally.
- Update `_update_fuzzer` in `setup.py` to support downloading fuzzer binaries using `blobs.read_blob_to_disk` when running on a trusted bot (non-uworker), removing the strict dependency on signed URLs for local execution.
- Add unit tests for `_update_fuzzer` in `setup_test.py` covering local and uworker scenarios.

Author: google-labs-jules[bot]

src/clusterfuzz/_internal/bot/tasks/setup.py

@@ -624,8 +624,12 @@ def _update_fuzzer(
 
   # Copy the archive to local disk and unpack it.
   archive_path = os.path.join(fuzzer_directory, fuzzer.filename)
-  if not storage.download_signed_url_to_file(update_input.fuzzer_download_url,
-                                             archive_path):
+  if not environment.is_uworker():
+    if not blobs.read_blob_to_disk(fuzzer.blobstore_key, archive_path):
+      logs.error('Failed to copy fuzzer archive.')
+      return False
+  elif not storage.download_signed_url_to_file(update_input.fuzzer_download_url,
+                                               archive_path):
     logs.error('Failed to copy fuzzer archive.')
     return False
 

src/clusterfuzz/_internal/bot/tasks/task_types.py

@@ -225,7 +225,7 @@ def execute(self, task_argument, job_type, uworker_env):
     'analyze': UTask,
     'blame': TrustedTask,
     'corpus_pruning': UTask,
-    'fuzz': UTask,
+    'fuzz': UTaskLocalExecutor,
     'impact': TrustedTask,
     'minimize': UTask,
     'progression': UTask,

src/clusterfuzz/_internal/tests/core/bot/tasks/setup_test.py

@@ -472,3 +472,74 @@ def test_prepare_env_fails(self):
     self.assertIsNone(path)
     self.mock_logs['error'].assert_called_with(
         'Error setting up testcase locally: mock prepare error')
+
+@test_utils.with_cloud_emulators('datastore')
+class UpdateFuzzerTest(unittest.TestCase):
+  """Tests _update_fuzzer."""
+
+  def setUp(self):
+    helpers.patch_environ(self)
+    helpers.patch(self, [
+        'clusterfuzz._internal.google_cloud_utils.storage.download_signed_url_to_file',
+        'clusterfuzz._internal.google_cloud_utils.blobs.read_blob_to_disk',
+        'clusterfuzz._internal.system.shell.remove_directory',
+        'clusterfuzz._internal.system.shell.remove_file',
+        'clusterfuzz._internal.system.archive.open',
+        'clusterfuzz._internal.build_management.revisions.write_revision_to_revision_file',
+        'clusterfuzz._internal.build_management.revisions.needs_update',
+        'os.path.exists',
+        'os.chmod',
+    ])
+    self.mock.remove_directory.return_value = True
+    self.mock.needs_update.return_value = True
+    self.mock.exists.return_value = True
+
+    self.fuzzer_name = 'test_fuzzer'
+    self.fuzzer = data_types.Fuzzer(
+        name=self.fuzzer_name, filename='fuzzer.zip', executable_path='fuzzer_exe', blobstore_key='blob_key', revision=123)
+    self.update_input = uworker_msg_pb2.SetupInput(
+        fuzzer_name=self.fuzzer_name,
+        fuzzer=uworker_io.entity_to_protobuf(self.fuzzer),
+        fuzzer_download_url='https://signed_url')
+    self.fuzzer_directory = '/fuzzer_dir'
+    self.version_file = '/fuzzer_dir/version'
+
+  def test_update_fuzzer_local(self):
+    """Test update_fuzzer when local (not uworker)."""
+    environment.set_value('UWORKER', False) # Not uworker
+    self.mock.read_blob_to_disk.return_value = True
+
+    result = setup._update_fuzzer(self.update_input, self.fuzzer_directory, self.version_file)
+
+    self.assertTrue(result)
+    self.mock.read_blob_to_disk.assert_called_once_with('blob_key', '/fuzzer_dir/fuzzer.zip')
+    self.mock.download_signed_url_to_file.assert_not_called()
+
+  def test_update_fuzzer_uworker(self):
+    """Test update_fuzzer when uworker."""
+    environment.set_value('UWORKER', True)
+    self.mock.download_signed_url_to_file.return_value = True
+
+    result = setup._update_fuzzer(self.update_input, self.fuzzer_directory, self.version_file)
+
+    self.assertTrue(result)
+    self.mock.download_signed_url_to_file.assert_called_once_with('https://signed_url', '/fuzzer_dir/fuzzer.zip')
+    self.mock.read_blob_to_disk.assert_not_called()
+
+  def test_update_fuzzer_local_fail(self):
+    """Test update_fuzzer fail local."""
+    environment.set_value('UWORKER', False)
+    self.mock.read_blob_to_disk.return_value = False
+
+    result = setup._update_fuzzer(self.update_input, self.fuzzer_directory, self.version_file)
+
+    self.assertFalse(result)
+
+  def test_update_fuzzer_uworker_fail(self):
+    """Test update_fuzzer fail uworker."""
+    environment.set_value('UWORKER', True)
+    self.mock.download_signed_url_to_file.return_value = False
+
+    result = setup._update_fuzzer(self.update_input, self.fuzzer_directory, self.version_file)
+
+    self.assertFalse(result)