[YoutubeDL] Protect from infinite recursion due to recursively nested playlists (closes #27833)

youtube_dl/YoutubeDL.py

@@ -338,6 +338,8 @@ class YoutubeDL(object):
     _pps = []
     _download_retcode = None
     _num_downloads = None
+    _playlist_level = 0
+    _playlist_urls = set()
     _screen_file = None
 
     def __init__(self, params=None, auto_init=True):
@@ -906,8 +908,51 @@ class YoutubeDL(object):
             return self.process_ie_result(
                 new_result, download=download, extra_info=extra_info)
         elif result_type in ('playlist', 'multi_video'):
+            # Protect from infinite recursion due to recursively nested playlists
+            # (see https://github.com/ytdl-org/youtube-dl/issues/27833)
+            webpage_url = ie_result['webpage_url']
+            if webpage_url in self._playlist_urls:
+                self.to_screen(
+                    '[download] Skipping already downloaded playlist: %s'
+                    % ie_result.get('title') or ie_result.get('id'))
+                return
+
+            self._playlist_level += 1
+            self._playlist_urls.add(webpage_url)
+            try:
+                return self.__process_playlist(ie_result, download)
+            finally:
+                self._playlist_level -= 1
+                if not self._playlist_level:
+                    self._playlist_urls.clear()
+        elif result_type == 'compat_list':
+            self.report_warning(
+                'Extractor %s returned a compat_list result. '
+                'It needs to be updated.' % ie_result.get('extractor'))
+
+            def _fixup(r):
+                self.add_extra_info(
+                    r,
+                    {
+                        'extractor': ie_result['extractor'],
+                        'webpage_url': ie_result['webpage_url'],
+                        'webpage_url_basename': url_basename(ie_result['webpage_url']),
+                        'extractor_key': ie_result['extractor_key'],
+                    }
+                )
+                return r
+            ie_result['entries'] = [
+                self.process_ie_result(_fixup(r), download, extra_info)
+                for r in ie_result['entries']
+            ]
+            return ie_result
+        else:
+            raise Exception('Invalid result type: %s' % result_type)
+
+    def __process_playlist(self, ie_result, download):
         # We process each entry in the playlist
         playlist = ie_result.get('title') or ie_result.get('id')
+
         self.to_screen('[download] Downloading playlist: %s' % playlist)
 
         playlist_results = []
@@ -1015,29 +1060,6 @@ class YoutubeDL(object):
         ie_result['entries'] = playlist_results
         self.to_screen('[download] Finished downloading playlist: %s' % playlist)
         return ie_result
-        elif result_type == 'compat_list':
-            self.report_warning(
-                'Extractor %s returned a compat_list result. '
-                'It needs to be updated.' % ie_result.get('extractor'))
-
-            def _fixup(r):
-                self.add_extra_info(
-                    r,
-                    {
-                        'extractor': ie_result['extractor'],
-                        'webpage_url': ie_result['webpage_url'],
-                        'webpage_url_basename': url_basename(ie_result['webpage_url']),
-                        'extractor_key': ie_result['extractor_key'],
-                    }
-                )
-                return r
-            ie_result['entries'] = [
-                self.process_ie_result(_fixup(r), download, extra_info)
-                for r in ie_result['entries']
-            ]
-            return ie_result
-        else:
-            raise Exception('Invalid result type: %s' % result_type)
 
     @__handle_extraction_exceptions
     def __process_iterable_entry(self, entry, download, extra_info):