fix: prevent recursion error when SharePoint folder is empty (#36372)

api/core/app/apps/pipeline/pipeline_generator.py

@@ -791,10 +791,25 @@ class PipelineGenerator(BaseAppGenerator):
         all_files: list,
         datasource_info: Mapping[str, Any],
         next_page_parameters: dict[str, Any] | None = None,
+        _visited_folder_ids: set[str] | None = None,
     ):
         """
         Get files in a folder.
+
+        Recursively lists all files inside the given folder prefix.
+        ``_visited_folder_ids`` tracks folders already expanded so that a
+        self-referencing folder (where the API returns the folder as its own
+        child) cannot cause infinite recursion.
         """
+        if _visited_folder_ids is None:
+            _visited_folder_ids = set()
+
+        # Guard: skip folders we have already expanded to prevent infinite
+        # recursion from self-referencing folder entries in the API response.
+        if prefix in _visited_folder_ids:
+            return
+        _visited_folder_ids.add(prefix)
+
         result_generator = datasource_runtime.online_drive_browse_files(
             user_id=user_id,
             request=OnlineDriveBrowseFilesRequest(
@@ -806,10 +821,14 @@ class PipelineGenerator(BaseAppGenerator):
             provider_type=datasource_runtime.datasource_provider_type(),
         )
         is_truncated = False
+        has_files = False
         for result in result_generator:
             for files in result.result:
                 for file in files.files:
+                    has_files = True
                     if file.type == "folder":
+                        if file.id in _visited_folder_ids:
+                            continue
                         self._get_files_in_folder(
                             datasource_runtime,
                             file.id,
@@ -818,6 +837,7 @@ class PipelineGenerator(BaseAppGenerator):
                             all_files,
                             datasource_info,
                             None,
+                            _visited_folder_ids,
                         )
                     else:
                         all_files.append(
@@ -830,7 +850,17 @@ class PipelineGenerator(BaseAppGenerator):
                 is_truncated = files.is_truncated
                 next_page_parameters = files.next_page_parameters
 
-        if is_truncated:
+        # Guard: only follow pagination when the API actually returned files.
+        # An empty folder that incorrectly reports ``is_truncated=True`` would
+        # otherwise recurse forever on the same empty page.
+        if is_truncated and has_files:
             self._get_files_in_folder(
-                datasource_runtime, prefix, bucket, user_id, all_files, datasource_info, next_page_parameters
+                datasource_runtime,
+                prefix,
+                bucket,
+                user_id,
+                all_files,
+                datasource_info,
+                next_page_parameters,
+                _visited_folder_ids,
             )

api/tests/unit_tests/core/app/apps/pipeline/test_pipeline_generator.py

@@ -717,3 +717,129 @@ def test_get_files_in_folder_recurses_and_collects(generator):
     )
 
     assert {f["id"] for f in all_files} == {"f1", "f2"}
+
+
+def test_get_files_in_folder_handles_empty_folder(generator):
+    """An empty folder must return an empty file list without recursion errors."""
+
+    class FilesPage:
+        def __init__(self, files, is_truncated=False, next_page_parameters=None):
+            self.files = files
+            self.is_truncated = is_truncated
+            self.next_page_parameters = next_page_parameters
+
+    class Result:
+        def __init__(self, result):
+            self.result = result
+
+    class Runtime:
+        def datasource_provider_type(self):
+            return DatasourceProviderType.ONLINE_DRIVE
+
+        def online_drive_browse_files(self, user_id, request, provider_type):
+            # Empty folder: returns a page with no files, not truncated
+            return iter([Result([FilesPage([], False, None)])])
+
+    runtime = Runtime()
+    all_files: list = []
+
+    generator._get_files_in_folder(
+        datasource_runtime=runtime,
+        prefix="empty-folder",
+        bucket="b",
+        user_id="user",
+        all_files=all_files,
+        datasource_info={},
+    )
+
+    assert all_files == []
+
+
+def test_get_files_in_folder_handles_empty_folder_with_false_truncation(generator):
+    """An empty folder that incorrectly reports is_truncated=True must not recurse forever."""
+
+    call_count = 0
+
+    class FilesPage:
+        def __init__(self, files, is_truncated=False, next_page_parameters=None):
+            self.files = files
+            self.is_truncated = is_truncated
+            self.next_page_parameters = next_page_parameters
+
+    class Result:
+        def __init__(self, result):
+            self.result = result
+
+    class Runtime:
+        def datasource_provider_type(self):
+            return DatasourceProviderType.ONLINE_DRIVE
+
+        def online_drive_browse_files(self, user_id, request, provider_type):
+            nonlocal call_count
+            call_count += 1
+            # Empty folder that incorrectly claims truncation
+            return iter([Result([FilesPage([], True, {"page": 2})])])
+
+    runtime = Runtime()
+    all_files: list = []
+
+    generator._get_files_in_folder(
+        datasource_runtime=runtime,
+        prefix="buggy-folder",
+        bucket="b",
+        user_id="user",
+        all_files=all_files,
+        datasource_info={},
+    )
+
+    assert all_files == []
+    # Should only be called once -- the empty-page guard prevents further recursion
+    assert call_count == 1
+
+
+def test_get_files_in_folder_handles_self_referencing_folder(generator):
+    """A folder that lists itself as a child must not recurse infinitely."""
+
+    class File:
+        def __init__(self, id, name, type):
+            self.id = id
+            self.name = name
+            self.type = type
+
+    class FilesPage:
+        def __init__(self, files, is_truncated=False, next_page_parameters=None):
+            self.files = files
+            self.is_truncated = is_truncated
+            self.next_page_parameters = next_page_parameters
+
+    class Result:
+        def __init__(self, result):
+            self.result = result
+
+    call_count = 0
+
+    class Runtime:
+        def datasource_provider_type(self):
+            return DatasourceProviderType.ONLINE_DRIVE
+
+        def online_drive_browse_files(self, user_id, request, provider_type):
+            nonlocal call_count
+            call_count += 1
+            # The folder returns itself as a child (self-reference)
+            return iter([Result([FilesPage([File("self-ref", "myfolder", "folder")], False, None)])])
+
+    runtime = Runtime()
+    all_files: list = []
+
+    generator._get_files_in_folder(
+        datasource_runtime=runtime,
+        prefix="self-ref",
+        bucket="b",
+        user_id="user",
+        all_files=all_files,
+        datasource_info={},
+    )
+
+    assert all_files == []
+    # Should only be called once -- the visited-set guard prevents re-entry
+    assert call_count == 1