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

I have a single file solution with the following advantages: - No external libraries. (Other than ctypes) - Doesn't require the process to be opened in a specific way.

The solution is adapted from this stack overflow post, but I think it's much more elegant in python.

import os
import signal
import subprocess
import sys
import time

# Terminates a Windows console app sending Ctrl-C
def terminateConsole(processId: int, timeout: int = None) -> bool:
    currentFilePath = os.path.abspath(__file__)
    # Call the below code in a separate process. This is necessary due to the FreeConsole call.
    try:
        code = subprocess.call('{} {} {}'.format(sys.executable, currentFilePath, processId), timeout=timeout)
        if code == 0: return True
    except subprocess.TimeoutExpired:
        pass

    # Backup plan
    subprocess.call('taskkill /F /PID {}'.format(processId))


if __name__ == '__main__':
    pid = int(sys.argv[1])

    import ctypes
    kernel = ctypes.windll.kernel32

    r = kernel.FreeConsole()
    if r == 0: exit(-1)
    r = kernel.AttachConsole(pid)
    if r == 0: exit(-1)
    r = kernel.SetConsoleCtrlHandler(None, True)
    if r == 0: exit(-1)
    r = kernel.GenerateConsoleCtrlEvent(0, 0)
    if r == 0: exit(-1)
    r = kernel.FreeConsole()
    if r == 0: exit(-1)

    # use tasklist to wait while the process is still alive.
    while True:
        time.sleep(1)
        # We pass in stdin as PIPE because there currently is no Console, and stdin is currently invalid.
        searchOutput: bytes = subprocess.check_output('tasklist /FI "PID eq {}"'.format(pid), stdin=subprocess.PIPE)
        if str(pid) not in searchOutput.decode(): break;

    # The following two commands are not needed since we're about to close this script.
    # You can leave them here if you want to do more console operations.
    r = kernel.SetConsoleCtrlHandler(None, False)
    if r == 0: exit(-1)
    r = kernel.AllocConsole()
    if r == 0: exit(-1)

    exit(0)