gh-141570: can_colorize: Expect fileno() to raise OSError, as documented by hroncok · Pull Request #141716 · python/cpython

hroncok · 2025-11-18T13:43:26Z

In Fedora, we've been given a slightly incomplete reproducer for a problematic Python 3.14 color-related change in argparse that leads to an exception when Python is used from mod_wsgi: https://bugzilla.redhat.com/2414940

mod_wsgi replaces sys.stdout with a custom object that raises OSError on .fileno():

https://github.com/GrahamDumpleton/mod_wsgi/blob/8460dbfcd5c7108892b3cde9fab7cbc1caa27886/src/server/wsgi_logger.c#L434-L440

This should be supported, as the documentation of fileno explicitly says:

An OSError is raised if the IO object does not use a file descriptor.

https://docs.python.org/3.14/library/io.html#io.IOBase.fileno

The previously expected exception inherits from OSError, so it is still expected.

Fixes #141570

Issue: _colorize.can_colorize() raises when sys.stdout is mod_wsgi logger #141570

In Fedora, we've been given a slightly incomplete reproducer for a problematic Python 3.14 color-related change in argparse that leads to an exception when Python is used from mod_wsgi: https://bugzilla.redhat.com/2414940 mod_wsgi replaces sys.stdout with a custom object that raises OSError on .fileno(): https://github.com/GrahamDumpleton/mod_wsgi/blob/8460dbfcd5c7108892b3cde9fab7cbc1caa27886/src/server/wsgi_logger.c#L434-L440 This should be supported, as the documentation of fileno explicitly says: > An OSError is raised if the IO object does not use a file descriptor. https://docs.python.org/3.14/library/io.html#io.IOBase.fileno The previously expected exception inherits from OSError, so it is still expected. Fixes python#141570

Lib/test/test__colorize.py

Misc/NEWS.d/next/Library/2025-11-18-14-39-31.gh-issue-141570.q3n984.rst

Lib/test/test__colorize.py

…3n984.rst Co-authored-by: Cody Maloney <cmaloney@users.noreply.github.com>

hroncok · 2025-11-19T12:32:32Z

@cmaloney Thanks for the review and suggestions.

…41570.q3n984.rst

vstinner

LGTM

Misc/NEWS.d/next/Library/2025-11-18-14-39-31.gh-issue-141570.q3n984.rst

…3n984.rst Co-authored-by: Victor Stinner <vstinner@python.org>

vstinner · 2025-11-19T13:47:30Z

@hugovk: Do you want to double check this change?

hugovk

Thanks!

miss-islington-app · 2025-11-19T14:02:55Z

Thanks @hroncok for the PR, and @vstinner for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

…ocumented (pythonGH-141716) In Fedora, we've been given a slightly incomplete reproducer for a problematic Python 3.14 color-related change in argparse that leads to an exception when Python is used from mod_wsgi: https://bugzilla.redhat.com/2414940 mod_wsgi replaces sys.stdout with a custom object that raises OSError on .fileno(): https://github.com/GrahamDumpleton/mod_wsgi/blob/8460dbfcd5c7108892b3cde9fab7cbc1caa27886/src/server/wsgi_logger.c#L434-L440 This should be supported, as the documentation of fileno explicitly says: > An OSError is raised if the IO object does not use a file descriptor. https://docs.python.org/3.14/library/io.html#io.IOBase.fileno The previously expected exception inherits from OSError, so it is still expected. Fixes python#141570 (cherry picked from commit 96f496a) Co-authored-by: Miro Hrončok <miro@hroncok.cz> Co-authored-by: Cody Maloney <cmaloney@users.noreply.github.com> Co-authored-by: Victor Stinner <vstinner@python.org>

miss-islington-app · 2025-11-19T14:03:03Z

Sorry, @hroncok and @vstinner, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 96f496a949b05054d0d043c3085f00cec2f83bf5 3.13

bedevere-app · 2025-11-19T14:03:04Z

GH-141747 is a backport of this pull request to the 3.14 branch.

bedevere-app · 2025-11-19T14:06:32Z

GH-141748 is a backport of this pull request to the 3.13 branch.

vstinner · 2025-11-19T14:07:29Z

Merged, thanks for the fix @hroncok!

…ocumented (python#141716) In Fedora, we've been given a slightly incomplete reproducer for a problematic Python 3.14 color-related change in argparse that leads to an exception when Python is used from mod_wsgi: https://bugzilla.redhat.com/2414940 mod_wsgi replaces sys.stdout with a custom object that raises OSError on .fileno(): https://github.com/GrahamDumpleton/mod_wsgi/blob/8460dbfcd5c7108892b3cde9fab7cbc1caa27886/src/server/wsgi_logger.c#L434-L440 This should be supported, as the documentation of fileno explicitly says: > An OSError is raised if the IO object does not use a file descriptor. https://docs.python.org/3.14/library/io.html#io.IOBase.fileno The previously expected exception inherits from OSError, so it is still expected. Fixes python#141570 Co-authored-by: Cody Maloney <cmaloney@users.noreply.github.com> Co-authored-by: Victor Stinner <vstinner@python.org> (cherry picked from commit 96f496a)

…documented (#141716) (#141748) gh-141570: can_colorize: Expect fileno() to raise OSError, as documented (#141716) In Fedora, we've been given a slightly incomplete reproducer for a problematic Python 3.14 color-related change in argparse that leads to an exception when Python is used from mod_wsgi: https://bugzilla.redhat.com/2414940 mod_wsgi replaces sys.stdout with a custom object that raises OSError on .fileno(): https://github.com/GrahamDumpleton/mod_wsgi/blob/8460dbfcd5c7108892b3cde9fab7cbc1caa27886/src/server/wsgi_logger.c#L434-L440 This should be supported, as the documentation of fileno explicitly says: > An OSError is raised if the IO object does not use a file descriptor. https://docs.python.org/3.14/library/io.html#io.IOBase.fileno The previously expected exception inherits from OSError, so it is still expected. Fixes #141570 (cherry picked from commit 96f496a) Co-authored-by: Miro Hrončok <miro@hroncok.cz> Co-authored-by: Cody Maloney <cmaloney@users.noreply.github.com>

…documented (GH-141716) (#141747) gh-141570: can_colorize: Expect fileno() to raise OSError, as documented (GH-141716) In Fedora, we've been given a slightly incomplete reproducer for a problematic Python 3.14 color-related change in argparse that leads to an exception when Python is used from mod_wsgi: https://bugzilla.redhat.com/2414940 mod_wsgi replaces sys.stdout with a custom object that raises OSError on .fileno(): https://github.com/GrahamDumpleton/mod_wsgi/blob/8460dbfcd5c7108892b3cde9fab7cbc1caa27886/src/server/wsgi_logger.c#L434-L440 This should be supported, as the documentation of fileno explicitly says: > An OSError is raised if the IO object does not use a file descriptor. https://docs.python.org/3.14/library/io.html#io.IOBase.fileno The previously expected exception inherits from OSError, so it is still expected. Fixes #141570 (cherry picked from commit 96f496a) Co-authored-by: Miro Hrončok <miro@hroncok.cz> Co-authored-by: Cody Maloney <cmaloney@users.noreply.github.com> Co-authored-by: Victor Stinner <vstinner@python.org>

…ocumented (python#141716) In Fedora, we've been given a slightly incomplete reproducer for a problematic Python 3.14 color-related change in argparse that leads to an exception when Python is used from mod_wsgi: https://bugzilla.redhat.com/2414940 mod_wsgi replaces sys.stdout with a custom object that raises OSError on .fileno(): https://github.com/GrahamDumpleton/mod_wsgi/blob/8460dbfcd5c7108892b3cde9fab7cbc1caa27886/src/server/wsgi_logger.c#L434-L440 This should be supported, as the documentation of fileno explicitly says: > An OSError is raised if the IO object does not use a file descriptor. https://docs.python.org/3.14/library/io.html#io.IOBase.fileno The previously expected exception inherits from OSError, so it is still expected. Fixes python#141570 Co-authored-by: Cody Maloney <cmaloney@users.noreply.github.com> Co-authored-by: Victor Stinner <vstinner@python.org>

hroncok requested a review from hugovk as a code owner November 18, 2025 13:43

bedevere-app bot added the awaiting review label Nov 18, 2025

hroncok changed the title ~~can_colorize: Expect fileno() to raise OSError, as documented~~ gh-141570: can_colorize: Expect fileno() to raise OSError, as documented Nov 18, 2025

bedevere-app bot mentioned this pull request Nov 18, 2025

_colorize.can_colorize() raises when sys.stdout is mod_wsgi logger #141570

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fixup! can_colorize: Expect fileno() to raise OSError, as documented

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hroncok and others added 2 commits November 19, 2025 13:31

Update Misc/NEWS.d/next/Library/2025-11-18-14-39-31.gh-issue-141570.q…

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…3n984.rst Co-authored-by: Cody Maloney <cmaloney@users.noreply.github.com>

Update Lib/test/test__colorize.py

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hroncok added 2 commits November 19, 2025 13:48

fixup! Update Misc/NEWS.d/next/Library/2025-11-18-14-39-31.gh-issue-1…

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…41570.q3n984.rst

fixup! Update Misc/NEWS.d/next/Library/2025-11-18-14-39-31.gh-issue-1…

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hugovk added needs backport to 3.13 bugs and security fixes needs backport to 3.14 bugs and security fixes labels Nov 19, 2025

vstinner merged commit 96f496a into python:main Nov 19, 2025
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can_colorize: Expect fileno() to raise OSError, as documented termcolor/termcolor#126

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gh-141570: can_colorize: Expect fileno() to raise OSError, as documented#141716

gh-141570: can_colorize: Expect fileno() to raise OSError, as documented#141716
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