Fix for recursive symlink issue #4669 (#4670)

* This is a potential fix to issue #4669.  The fix simply catches the
recusrive symlink error and moves on.  It is possibble that the
try/except belongs in the utils but I wanted to limit the scope.

* It looks like too many levels is error number 40 on linux.

* Switch to using errno instead of hardcoding the number.

* Fix spelling, smarter assert methods

* Log unrecognised errors and continue listing directory

* Skip recursive symlink test entirely on Windows

* Fix which test is skipped on Windows

Co-authored-by: Thomas Kluyver <[email protected]>

Author: scanon

notebook/services/contents/filemanager.py

@@ -330,12 +330,20 @@ def _dir_model(self, path, content=True):
                     self.log.debug("%s not a regular file", os_path)
                     continue
 
-                if self.should_list(name):
-                    if self.allow_hidden or not is_file_hidden(os_path, stat_res=st):
-                        contents.append(
-                                self.get(path='%s/%s' % (path, name), content=False)
+                try:
+                    if self.should_list(name):
+                        if self.allow_hidden or not is_file_hidden(os_path, stat_res=st):
+                            contents.append(
+                                    self.get(path='%s/%s' % (path, name), content=False)
+                            )
+                except OSError as e:
+                    # ELOOP: recursive symlink
+                    if e.errno != errno.ELOOP:
+                        self.log.warning(
+                            "Unknown error checking if file %r is hidden",
+                            os_path,
+                            exc_info=True,
                         )
-
             model['format'] = 'json'
 
         return model

notebook/services/contents/tests/test_manager.py

@@ -129,6 +129,26 @@ def test_bad_symlink(self):
             # broken symlinks should still be shown in the contents manager
             self.assertTrue('bad symlink' in contents)
 
+    @dec.skipif(sys.platform == 'win32')
+    def test_recursive_symlink(self):
+        with TemporaryDirectory() as td:
+            cm = FileContentsManager(root_dir=td)
+            path = 'test recursive symlink'
+            _make_dir(cm, path)
+            os_path = cm._get_os_path(path)
+            os.symlink("recursive", os.path.join(os_path, "recursive"))
+            file_model = cm.new_untitled(path=path, ext='.txt')
+
+            model = cm.get(path)
+
+            contents = {
+                content['name']: content for content in model['content']
+            }
+            self.assertIn('untitled.txt', contents)
+            self.assertEqual(contents['untitled.txt'], file_model)
+            # recursive symlinks should not be shown in the contents manager
+            self.assertNotIn('recursive', contents)
+
     @dec.skipif(sys.platform == 'win32' and sys.version_info[0] < 3)
     def test_good_symlink(self):
         with TemporaryDirectory() as td: