gh-135329: prevent infinite traceback loop on Ctrl-C for strace by yihong0618 · Pull Request #138133 · python/cpython

yihong0618 · 2025-08-25T08:42:26Z

This patch fix strace can not ctrl+c error

and follow the work so add co-author dura0ok

but that fix is not enough, there is a another problem in the queue
we need to consider

cc @picnixz @cmaloney you can try this patch.

Issue: Running python REPL under another program + Ctrl-C results in an exception traceback #135329

Signed-off-by: yihong0618 <zouzou0208@gmail.com> Co-authored-by: dura0ok <slpmcf@gmail.com>

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

ZeroIntensity

Please try adding a test case.

Lib/_pyrepl/unix_console.py

Misc/NEWS.d/next/Library/2025-08-25-18-06-04.gh-issue-138133.Zh9rGo.rst

yihong0618 · 2025-08-25T10:52:20Z

Please try adding a test case.

tried but kind of hard...
It's kind of hard to make some env like strace

ZeroIntensity · 2025-08-25T11:31:04Z

Why not just run with strace itself with subprocess?

yihong0618 · 2025-08-25T11:32:34Z

Why not just run with strace itself with subprocess?

ok but some env do not have it, is that OK?

ZeroIntensity · 2025-08-25T11:33:37Z

Yeah, we just skip the test on those platforms.

yihong0618 · 2025-08-25T11:35:24Z

Yeah, we just skip the test on those platforms.

just found cpython already have strace maybe

will try thanks for the info

Lib/test/support/strace_helper.py
11:_strace_binary = "/usr/bin/strace"
27:    strace_returncode: int
30:    """The event messages generated by strace. This is very similar to the
31:    stderr strace produces with returncode marker section removed."""
40:        strings which would mix into the strace output."""
97:def strace_python(code, strace_flags, check=True):
98:    """Run strace and return the trace.
100:    Sets strace_returncode and python_returncode to `-1` on error."""
105:            strace_returncode=-1,
111:    # Run strace, and get out the raw text
116:            __run_using_command=[_strace_binary] + strace_flags,
128:        return _make_error("Expected strace events and exit code line",
140:    return StraceResult(strace_returncode=res.rc,
147:def get_events(code, strace_flags, prelude, cleanup):
162:    trace = strace_python(to_run, strace_flags)
167:def get_syscalls(code, strace_flags, prelude="", cleanup="",
170:    events = get_events(code, strace_flags, prelude=prelude, cleanup=cleanup)
180:def _can_strace():
181:    res = strace_python("import sys; sys.exit(0)",
182:                        # --trace option needs strace 5.5 (gh-133741)
185:    if res.strace_returncode == 0 and res.python_returncode == 0:
191:def requires_strace():
193:        return unittest.skip("Linux only, requires strace.")
203:        return unittest.skip("LeakSanitizer does not work under ptrace (strace, gdb, etc)")
205:    return unittest.skipUnless(_can_strace(), "Requires working strace")
208:__all__ = ["filter_memory", "get_events", "get_syscalls", "requires_strace",
209:           "strace_python", "StraceEvent", "StraceResult"]

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

Lib/_pyrepl/unix_console.py

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

yihong0618 · 2025-08-25T21:48:36Z

tests case added

in main

yihong@ubuntu:~/cpython$ ./python -m unittest test.test_pyrepl.test_unix_console.TestUnixConsoleEIOHandling
FF
======================================================================
FAIL: test_eio_error_handling_in_prepare (test.test_pyrepl.test_unix_console.TestUnixConsoleEIOHandling.test_eio_error_handling_in_prepare)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/yihong/cpython/Lib/test/test_pyrepl/test_unix_console.py", line 330, in test_eio_error_handling_in_prepare
    console.prepare()
    ~~~~~~~~~~~~~~~^^
  File "/home/yihong/cpython/Lib/_pyrepl/unix_console.py", line 339, in prepare
    tcsetattr(self.input_fd, termios.TCSADRAIN, raw)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/yihong/cpython/Lib/unittest/mock.py", line 1175, in __call__
    return self._mock_call(*args, **kwargs)
           ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/home/yihong/cpython/Lib/unittest/mock.py", line 1179, in _mock_call
    return self._execute_mock_call(*args, **kwargs)
           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/home/yihong/cpython/Lib/unittest/mock.py", line 1234, in _execute_mock_call
    raise effect
termios.error: (5, 'Input/output error')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/yihong/cpython/Lib/unittest/mock.py", line 1432, in patched
    return func(*newargs, **newkeywargs)
  File "/home/yihong/cpython/Lib/test/test_pyrepl/test_unix_console.py", line 333, in test_eio_error_handling_in_prepare
    self.fail("EIO error should have been handled gracefully in prepare()")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: EIO error should have been handled gracefully in prepare()

======================================================================
FAIL: test_eio_error_handling_in_restore (test.test_pyrepl.test_unix_console.TestUnixConsoleEIOHandling.test_eio_error_handling_in_restore)
Test that EIO errors during restore() are handled gracefully.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/yihong/cpython/Lib/test/test_pyrepl/test_unix_console.py", line 360, in test_eio_error_handling_in_restore
    console.restore()
    ~~~~~~~~~~~~~~~^^
  File "/home/yihong/cpython/Lib/_pyrepl/unix_console.py", line 371, in restore
    tcsetattr(self.input_fd, termios.TCSADRAIN, self.__svtermstate)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/yihong/cpython/Lib/unittest/mock.py", line 1175, in __call__
    return self._mock_call(*args, **kwargs)
           ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/home/yihong/cpython/Lib/unittest/mock.py", line 1179, in _mock_call
    return self._execute_mock_call(*args, **kwargs)
           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/home/yihong/cpython/Lib/unittest/mock.py", line 1234, in _execute_mock_call
    raise effect
termios.error: (5, 'Input/output error')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/yihong/cpython/Lib/unittest/mock.py", line 1432, in patched
    return func(*newargs, **newkeywargs)
  File "/home/yihong/cpython/Lib/test/test_pyrepl/test_unix_console.py", line 363, in test_eio_error_handling_in_restore
    self.fail("EIO error should have been handled gracefully in restore()")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: EIO error should have been handled gracefully in restore()

----------------------------------------------------------------------
Ran 2 tests in 0.002s

FAILED (failures=2)

after this patch

yihong@ubuntu:~/cpython$ ./python -m unittest test.test_pyrepl.test_unix_console.TestUnixConsoleEIOHandling
..

Ran 2 tests in 0.001s

OK

cmaloney · 2025-08-25T23:25:38Z

👍 tested PR locally and resolves the issues I had using Ctrl-C when Python is running under strace.

thought: This wraps all the _pyrepl.fancy_termios.tcsetattr calls with "ignore errors.EIO"; it might make sense to just update _prepl.fancy_termios.tcsetattr (which wraps termios.tcsetattr already) to contain the try/except. Searching through _pyrepl only _pyrepl.unix_console uses _prepl.fancy_termios (and the one other termios.tcsetattr is in a finally where ignoring EIO would probably be reasonable as well)

yihong0618 · 2025-08-26T01:04:23Z

👍 tested PR locally and resolves the issues I had using Ctrl-C when Python is running under strace.

thought: This wraps all the _pyrepl.fancy_termios.tcsetattr calls with "ignore errors.EIO"; it might make sense to just update _prepl.fancy_termios.tcsetattr (which wraps termios.tcsetattr already) to contain the try/except. Searching through _pyrepl only _pyrepl.unix_console uses _prepl.fancy_termios (and the one other termios.tcsetattr is in a finally where ignoring EIO would probably be reasonable as well)

thanks let me test and wait for the reviewer check~

Lib/_pyrepl/unix_console.py

Lib/test/test_pyrepl/test_unix_console.py

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

yihong0618 · 2025-08-27T01:19:58Z

@ZeroIntensity @cmaloney Hi we can not add test for subprocess for this issue
because background run can not trigger eio error...

and FYI

this patch also fix

the code in the comments

#135329 (comment)

cmaloney · 2025-08-27T02:54:26Z

@ZeroIntensity @cmaloney Hi we can not add test for subprocess for this issue because background run can not trigger eio error...

This doesn't actually follow for me. pyrepl does have "like its at a terminal" tests (ex: https://github.com/python/cpython/blob/main/Lib/test/test_pyrepl/test_pyrepl.py#L40-L149). That we're adding another wrapping process (strace), and then that wrapping process is killed first (leaving the subprocess an orphan) seems like something that should be possible to replicate.

yihong0618 · 2025-08-29T06:05:25Z

@ZeroIntensity @cmaloney Hi we can not add test for subprocess for this issue because background run can not trigger eio error...

This doesn't actually follow for me. pyrepl does have "like its at a terminal" tests (ex: https://github.com/python/cpython/blob/main/Lib/test/test_pyrepl/test_pyrepl.py#L40-L149). That we're adding another wrapping process (strace), and then that wrapping process is killed first (leaving the subprocess an orphan) seems like something that should be possible to replicate.

not so simple you can refer this comment
#135329 (comment)

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

…/cpython into hy/fix_can_not_strace

yihong0618 · 2025-09-01T07:31:30Z

@ZeroIntensity test added strace with EIO

Lib/test/test_pyrepl/test_unix_console.py

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

picnixz · 2025-09-08T10:53:15Z

After reading through the issue I understand what you want to do. But I think we should extract that script into a separate file because it's too as a string-only script. Also, why can't we simply use the reproducer given by #135329 (comment) and perform the manual kills? is it because the test process would still be the parent process and so it's not possible?

yihong0618 · 2025-09-08T10:56:14Z

After reading through the issue I understand what you want to do. But I think we should extract that script into a separate file because it's too as a string-only script. Also, why can't we simply use the reproducer given by #135329 (comment) and perform the manual kills? is it because the test process would still be the parent process and so it's not possible?

yes we can not that script is not fully with EIO

will fix it later and try to make it better if I can. Thank you very much for the review

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

picnixz

I would suggest using better "messages" to print the success. Something like: SUCCESS or FAILURE[errno] should be sufficient and match return code.

Lib/test/test_pyrepl/eio_test_script.py

Lib/test/test_pyrepl/test_unix_console.py

Lib/test/test_pyrepl/eio_test_script.py

Lib/test/test_pyrepl/test_unix_console.py

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Changes were applied. Only final nitpicks remain.

miss-islington-app · 2025-09-16T10:39:07Z

Thanks @yihong0618 for the PR, and @ambv for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

…pythonGH-138133) (cherry picked from commit b9dbf6a) Co-authored-by: yihong <zouzou0208@gmail.com> Signed-off-by: yihong0618 <zouzou0208@gmail.com> Co-authored-by: dura0ok <slpmcf@gmail.com> Co-authored-by: graymon <greyschwinger@gmail.com> Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com> Co-authored-by: Łukasz Langa <lukasz@langa.pl>

miss-islington-app · 2025-09-16T10:39:15Z

Sorry, @yihong0618 and @ambv, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker b9dbf6acb34fd407d52899a6c154a1c57c9a424b 3.13

bedevere-app · 2025-09-16T10:39:20Z

GH-138973 is a backport of this pull request to the 3.14 branch.

…pythonGH-138133) Signed-off-by: yihong0618 <zouzou0208@gmail.com> Co-authored-by: dura0ok <slpmcf@gmail.com> Co-authored-by: graymon <greyschwinger@gmail.com> Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com> Co-authored-by: Łukasz Langa <lukasz@langa.pl> (cherry picked from commit b9dbf6a)

… strace (pythonGH-138133) (cherry picked from commit b9dbf6a) Co-authored-by: yihong <zouzou0208@gmail.com> Signed-off-by: yihong0618 <zouzou0208@gmail.com> Co-authored-by: dura0ok <slpmcf@gmail.com> Co-authored-by: graymon <greyschwinger@gmail.com> Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com> Co-authored-by: Łukasz Langa <lukasz@langa.pl>

GH-138133) (#138973) gh-135329: prevent infinite traceback loop on Ctrl-C for strace (GH-138133) (cherry picked from commit b9dbf6a) Signed-off-by: yihong0618 <zouzou0208@gmail.com> Co-authored-by: yihong <zouzou0208@gmail.com> Co-authored-by: dura0ok <slpmcf@gmail.com> Co-authored-by: graymon <greyschwinger@gmail.com> Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com> Co-authored-by: Łukasz Langa <lukasz@langa.pl>

fix: strace ./python will forever loop

ede576f

Signed-off-by: yihong0618 <zouzou0208@gmail.com> Co-authored-by: dura0ok <slpmcf@gmail.com>

yihong0618 requested review from ambv, lysnikolaou and pablogsal as code owners August 25, 2025 08:42

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Running python REPL under another program + Ctrl-C results in an exception traceback #135329

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fix: add news

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yihong0618 added 2 commits September 1, 2025 15:30

fix: add EIO erorr with strace test

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Merge branch 'hy/fix_can_not_strace' of https://github.com/yihong0618…

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yihong0618 and others added 2 commits September 12, 2025 17:06

Update Lib/_pyrepl/unix_console.py

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Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

fix: apply comments

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fix: test on windows

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Run the internal EIO test on any non-win32 plat

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Merge branch 'main' into pr-138133

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Treat ENXIO as success

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ambv added needs backport to 3.13 bugs and security fixes needs backport to 3.14 bugs and security fixes labels Sep 16, 2025

ambv merged commit b9dbf6a into python:main Sep 16, 2025
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gh-135329: prevent infinite traceback loop on Ctrl-C under external p… #135366

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yihong@ubuntu:~/cpython$ ./python -m unittest test.test_pyrepl.test_unix_console.TestUnixConsoleEIOHandling ..

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yihong0618 commented Aug 25, 2025 •

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yihong@ubuntu:~/cpython$ ./python -m unittest test.test_pyrepl.test_unix_console.TestUnixConsoleEIOHandling
..

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