Raise TimestampParseError instead of OverflowError for out-of-range timestamps

srt.py

@@ -250,7 +250,15 @@ def srt_timestamp_to_timedelta(timestamp):
     if match is None:
         raise TimestampParseError("Unparseable timestamp: {}".format(timestamp))
     hrs, mins, secs, msecs = [int(m) if m else 0 for m in match.groups()]
-    return timedelta(hours=hrs, minutes=mins, seconds=secs, milliseconds=msecs)
+    try:
+        return timedelta(hours=hrs, minutes=mins, seconds=secs, milliseconds=msecs)
+    except OverflowError:
+        # timedelta only holds up to ~2.7 million years, so a field with enough
+        # digits blows past that. This is still a bad timestamp as far as we're
+        # concerned, so surface it as one rather than leaking OverflowError.
+        raise TimestampParseError(
+            "Timestamp is too large to represent: {}".format(timestamp)
+        )
 
 
 def sort_and_reindex(subtitles, start_index=1, in_place=False, skip=True):

tests/test_srt.py

@@ -688,6 +688,18 @@ def test_bad_timestamp_format_raises(ts):
         srt.srt_timestamp_to_timedelta(ts)
 
 
+def test_out_of_range_timestamp_raises():
+    # A field big enough to overflow timedelta used to leak OverflowError
+    with pytest.raises(srt.TimestampParseError):
+        srt.srt_timestamp_to_timedelta("9999999999999999:00:00,000")
+
+
+def test_parse_out_of_range_timestamp_raises():
+    over_range = "1\n9999999999999999:00:00,000 --> 00:00:01,000\nhi\n\n"
+    with pytest.raises(srt.TimestampParseError):
+        list(srt.parse(over_range))
+
+
 @given(st.lists(subtitles()), st.lists(st.sampled_from(string.whitespace)))
 def test_can_parse_index_trailing_ws(input_subs, whitespace):
     out = ""