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"""
A person's Ctrl+C, delivered to a client run started by a test.
On Windows Ctrl+C is a console event, not a signal, so the run gets a hidden
console of its own and a helper attached to that console raises the event. The
run goes through a launcher that turns Ctrl+C handling back on first: a process
inherits "ignore Ctrl+C" from its parent, and whatever started the test suite
may have set it (an IDE, a CI runner, an agent's shell) where a person's console
never does — measured, the event then reached nothing at all.
"""
import subprocess
import sys
_LAUNCHER = ("import ctypes, signal, subprocess, sys\n"
"ctypes.windll.kernel32.SetConsoleCtrlHandler(None, 0)\n"
"signal.signal(signal.SIGINT, signal.SIG_IGN)\n"
"sys.exit(subprocess.call(sys.argv[1:]))\n")
# os._exit: with the console swapped, flushing stdout at exit fails (code 120).
_SENDER = ("import ctypes, os, sys\n"
"k = ctypes.windll.kernel32\n"
"k.FreeConsole()\n"
"ok = k.AttachConsole(int(sys.argv[1])) and k.SetConsoleCtrlHandler(None, 1)\n"
"os._exit(0 if ok and k.GenerateConsoleCtrlEvent(0, 0) else 1)\n")
def interruptible(argv: list[str], env: dict | None) -> subprocess.Popen:
"""`argv` started so that `ctrl_c` reaches it, its output read as UTF-8."""
extra: dict = {}
if sys.platform == "win32":
si = subprocess.STARTUPINFO()
si.dwFlags |= subprocess.STARTF_USESHOWWINDOW
si.wShowWindow = 0 # SW_HIDE
extra = {"creationflags": subprocess.CREATE_NEW_CONSOLE, "startupinfo": si}
argv = [sys.executable, "-c", _LAUNCHER, *argv]
return subprocess.Popen(argv, env=env, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
text=True, encoding="utf-8", **extra)
def ctrl_c(proc: subprocess.Popen) -> None:
if sys.platform != "win32":
import signal
proc.send_signal(signal.SIGINT)
return
subprocess.run([sys.executable, "-c", _SENDER, str(proc.pid)], check=True, timeout=30,
stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL,
creationflags=subprocess.CREATE_NO_WINDOW)
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