IronLanguages / IronLanguages/ironpython3

Duplicate file is closed when original file is closed

Open
#1,212 0 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Dominant language
C#
Stars
2.8k
Forks
316
Avg merge
1d 9h
Merged PRs (30d)
1

Description

From https://github.com/IronLanguages/ironpython2/issues/92:

import os

with open("temp.txt", "wb+") as f:
    f.write(b"test")
    f.seek(os.SEEK_SET, 0)
    x = os.dup(f.fileno())
    g = os.fdopen(x, "rb")

assert g.read() == b"test"

fails with:

io.UnsupportedOperation: File not open for reading

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the Python snippet using os.dup, os.fdopen, and the original file's close behavior. Trace the implementation of these file-descriptor operations and add or run a regression test showing that g remains readable after f is closed; done means the assertion succeeds without io.UnsupportedOperation.

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp, python
Domain
operating-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.