PythonCharmers/python-future

urllib.parse.unquote may return bytes

Open

#431 opened on Jan 21, 2019

View on GitHub
 (1 comment) (0 reactions) (1 assignee)Python (1,172 stars) (327 forks)batch import
0.19help wanted

Description

In Py3, unquote does not accept bytes: the first line if '%' not in string would throw exception.

However, in Py2, that line will not throw exception and perform the checking.

When there's no %, the return value is the argument. That is, when the argument type is bytes, the return value is bytes, too.

Code snippet excerption from src/future/backports/urllib/parse.py#L515:

def unquote(string):
  if '%' not in string:
    string.split
    return string      # bytes or unicode, depends on argument; Py3 never reach here
  ...
  return ''.join(res)  # unicode

Contributor guide

Tech stack
python
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic understanding of Python 2/3 string handlingFamiliarity with urllib.parse
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
The issue is in src/future/backports/urllib/parse.py at line 515. The function unquote should return str in both Python 2 and 3. The fix should ensure that when input is bytes, it is decoded or converted to str before processing. Consider adding a check for bytes type and converting using .decode('utf 8') or similar. The current code returns bytes if no '%' is in string, which is inconsistent. Check the Python 3 implementation for reference.