[utils] `LenientJSONDecoder`: Parse unclosed objects

yt_dlp/utils.py

@@ -593,21 +593,43 @@ def clean_html(html):
 
 
 class LenientJSONDecoder(json.JSONDecoder):
-    def __init__(self, *args, transform_source=None, ignore_extra=False, **kwargs):
+    # TODO: Write tests
+    def __init__(self, *args, transform_source=None, ignore_extra=False, close_objects=0, **kwargs):
         self.transform_source, self.ignore_extra = transform_source, ignore_extra
+        self._close_attempts = 2 * close_objects
         super().__init__(*args, **kwargs)
 
+    @staticmethod
+    def _close_object(err):
+        doc = err.doc[:err.pos]
+        # We need to add comma first to get the correct error message
+        if err.msg.startswith('Expecting \',\''):
+            return doc + ','
+        elif not doc.endswith(','):
+            return
+
+        if err.msg.startswith('Expecting property name'):
+            return doc[:-1] + '}'
+        elif err.msg.startswith('Expecting value'):
+            return doc[:-1] + ']'
+
     def decode(self, s):
         if self.transform_source:
             s = self.transform_source(s)
-        try:
-            if self.ignore_extra:
-                return self.raw_decode(s.lstrip())[0]
-            return super().decode(s)
-        except json.JSONDecodeError as e:
-            if e.pos is not None:
+        for attempt in range(self._close_attempts + 1):
+            try:
+                if self.ignore_extra:
+                    return self.raw_decode(s.lstrip())[0]
+                return super().decode(s)
+            except json.JSONDecodeError as e:
+                if e.pos is None:
+                    raise
+                elif attempt < self._close_attempts:
+                    s = self._close_object(e)
+                    if s is not None:
+                        continue
                 raise type(e)(f'{e.msg} in {s[e.pos-10:e.pos+10]!r}', s, e.pos)
-            raise
+        assert False, 'Too many attempts to decode JSON'
 
 
 def sanitize_open(filename, open_mode):