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GeezerVison is showing github.com — CYGWIN: warning on missing secure randomness function · Issue #148461 · python/cpython

CYGWIN: warning on missing secure randomness function #148461

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CYGWIN: warning on missing secure randomness function#148461
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OS-unsupportedinterpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

Description

@carlo-bramini
carlo-bramini
opened on Apr 12, 2026
Issue body actions

Bug report

Bug description:

While compiling latest sources of Python on CYGWIN, this warning is printed:

unable to use secure randomness

This happens because the platform is not handled into Objects\mimalloc\prim\unix\prim.c.
However, this can be fixed very easily because CYGWIN provides arc4random_buf(), which is already used by the ports for other plaforms.
So, the issue can be fixed by simply adding an || defined(__CYGWIN__) near __FreeBSD__, __NetBSD__ and others.

This is a patch for mimalloc, so see also #113141 for reference.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Windows

Linked PRs

  • gh-148461: use arc4random_buf() on CYGWIN #148462

Activity

  1. carlo-bramini
    added
    type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error
    on Apr 12, 2026
  2. carlo-bramini
    added a commit that references this issue on Apr 12, 2026

    pythongh-148461: use arc4random_buf() on CYGWIN

    dd4d338
  3. picnixz
    added
    interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)
    on Apr 12, 2026
  4. StanFromIreland
    added
    OS-unsupported
    on Apr 12, 2026
  5. github-project-automation
    added this to Unsupported platformson Apr 12, 2026
  6. vstinner
    added a commit that references this issue on May 13, 2026

    gh-148461: Use arc4random_buf() in mimalloc on Cygwin (#148462)

    fdf064c
  7. vstinner
    closed this as completedon May 13, 2026
  8. github-project-automation
    moved this to Done in Unsupported platformson May 13, 2026
  9. vstinner
    added a parent issue on May 15, 2026
    • Enhance Cygwin support #149879
  10. corona10
    added a commit that references this issue on Oct 22, 2026

    pythongh-159111: Restore arc4random_buf() usage on Cygwin in vendored…

    3f5299b
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    OS-unsupportedinterpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

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