python / python/cpython

[Windows] scandir returns filenotfound for long paths but os.walk does not

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3.9 (EOL) OS-windows tests topic-IO
Dominant language
Python
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Description

BPO 46084
Nosy @pfmoore, @tjguk, @jkloth, @zware, @serhiy-storchaka, @eryksun, @zooba
Files
  • test_dir_scan_dir.py: can be used to show filenotfound issue with long directory names. os_walk does not do the same thing.
  • test_os_walk.py: this script works just fine on the same directory structure.
  • test_dir_scan_dir.py: can be used to show filenotfound issue with long directory names. os_walk does not do the same thing.
  • Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = None
    closed_at = None
    created_at = <Date 2021-12-15.14:54:30.143>
    labels = ['expert-IO', 'tests', 'OS-windows', 'type-crash', '3.9']
    title = 'Python 3.9.6 scan_dir returns filenotfound on long paths, but os_walk does not'
    updated_at = <Date 2022-03-21.18:46:36.102>
    user = 'https://bugs.python.org/jschwar313'
    

    bugs.python.org fields:

    activity = <Date 2022-03-21.18:46:36.102>
    actor = 'jkloth'
    assignee = 'none'
    closed = False
    closed_date = None
    closer = None
    components = ['Tests', 'Windows', 'IO']
    creation = <Date 2021-12-15.14:54:30.143>
    creator = 'jschwar313'
    dependencies = []
    files = ['50492', '50493', '50495']
    hgrepos = []
    issue_num = 46084
    keywords = ['patch']
    message_count = 13.0
    messages = ['408607', '408608', '408617', '408619', '408621', '408623', '408625', '408626', '408632', '408634', '408636', '408643', '408649']
    nosy_count = 8.0
    nosy_names = ['paul.moore', 'tim.golden', 'jkloth', 'zach.ware', 'serhiy.storchaka', 'eryksun', 'steve.dower', 'jschwar313']
    pr_nums = []
    priority = 'normal'
    resolution = None
    stage = 'patch review'
    status = 'open'
    superseder = None
    type = 'crash'
    url = 'https://bugs.python.org/issue46084'
    versions = ['Python 3.9']
    

    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 running test_dir_scan_dir.py on Windows with the long directory structure described in the issue, then compare its behavior with test_os_walk.py. Inspect the scandir-related path handling and verify that long paths no longer produce FileNotFoundError while os.walk continues to work. Confirm the behavior with a focused regression test.

    Written by the indexing model from the issue text.

    Assessment

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

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