Sending ^C to Python subprocess objects on Windows

Question

I have a test harness (written in Python) that needs to shut down the program under test (written in C) by sending it ^C. On Unix,

proc.send_sign         


        

Answer 1

My solution also involves a wrapper script, but it does not need IPC, so it is far simpler to use.

The wrapper script first detaches itself from any existing console, then attach to the target console, then files the Ctrl-C event.

import ctypes
import sys

kernel = ctypes.windll.kernel32

pid = int(sys.argv[1])
kernel.FreeConsole()
kernel.AttachConsole(pid)
kernel.SetConsoleCtrlHandler(None, 1)
kernel.GenerateConsoleCtrlEvent(0, 0)
sys.exit(0)

The initial process must be launched in a separate console so that the Ctrl-C event will not leak. Example

p = subprocess.Popen(['some_command'], creationflags=subprocess.CREATE_NEW_CONSOLE)

# Do something else

subprocess.check_call([sys.executable, 'ctrl_c.py', str(p.pid)]) # Send Ctrl-C

where I named the wrapper script as ctrl_c.py.