[New-bugs-announce] [issue42962] Windows: SystemError during os.kill(..., signal.CTRL_C_EVENT)

William Schwartz report at bugs.python.org
Mon Jan 18 17:12:34 EST 2021

New submission from William Schwartz <wkschwartz at gmail.com>:

I don't have an automated test at this time, but here's how to get os.kill to raise SystemError. I did this on Windows 10 version 20H2 (build 19042.746) with Pythons 3.7.7, 3.8.5, and 3.9.1. os_kill_impl at Modules/posixmodule.c:7833 does not appear to have been modified recently (but I haven't checked its transitive callees), so I imagine you can get the same behavior from os.kill on Python 3.10.

1. Open two consoles, A and B. (I'm using tabs in Windows Terminal, if that matters.)
2. In console A, type but DO NOT EXECUTE the following command:

python -c"import os, signal; os.kill(, signal.CTRL_C_EVENT)"

Move your cursor back before the comma.

3. In console B, create a process that does nothing but print its process identifier and wait long enough for you to type it in console A:

python -c"import os, time; print(os.getpid()); time.sleep(60); print('exiting cleanly')"

Copy or remember the printed PID. Hurry to step 4 before your 60 seconds expires!

4. In console A, type the PID from console B and execute the command.
5. In console B, confirm that the Python exited without printing "exiting cleanly". Oddly, `echo %errorlevel%` will print `0` rather than `-1073741510` (which is `2**32 - 0xc000013a`, the CTRL_C_EVENT exit code), which is what it prints after `python -c"raise KeyboardInturrupt"`.
6. In console A, you should see the following traceback.

OSError: [WinError 87] The parameter is incorrect

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
SystemError: <built-in function kill> returned a result with an error set

components: Extension Modules, Windows
messages: 385235
nosy: William.Schwartz, ncoghlan, paul.moore, petr.viktorin, steve.dower, tim.golden, zach.ware
priority: normal
severity: normal
status: open
title: Windows: SystemError during os.kill(..., signal.CTRL_C_EVENT)
type: behavior
versions: Python 3.10, Python 3.7, Python 3.8, Python 3.9

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