import asyncio
import os
import sys
from asyncio import events
from asyncio.unix_events import _PidfdChildWatcher
from os import waitstatus_to_exitcode
from unittest import mock


def fixed_do_wait(self, pid, pidfd, callback, args):
    loop = events.get_running_loop()
    loop._remove_reader(pidfd)
    try:
        try:
            _, status = os.waitpid(pid, 0)
        except ChildProcessError:
            returncode = 255
        else:
            returncode = waitstatus_to_exitcode(status)
    finally:
        os.close(pidfd)
    callback(pid, returncode, *args)


async def run_case(label, do_wait, exc):
    pid = os.posix_spawn(sys.executable, [sys.executable, "-c", ""], os.environ)
    pidfd = os.pidfd_open(pid)
    with mock.patch("os.waitpid", side_effect=exc):
        try:
            do_wait(_PidfdChildWatcher(), pid, pidfd, lambda *a: None, ())
        except BaseException:
            pass
    try:
        print(os.fstat(pidfd))
        leaked = True
    except OSError:
        leaked = False
    print(f"  [{label}] leaked={leaked}")
    if leaked:
        os.close(pidfd)
    os.waitpid(pid, 0)


async def main():
    print("current:")
    await run_case("OSError", _PidfdChildWatcher._do_wait, OSError("boom"))
    await run_case("KeyboardInterrupt", _PidfdChildWatcher._do_wait, KeyboardInterrupt())
    print("fixed:")
    await run_case("OSError", fixed_do_wait, OSError("boom"))
    await run_case("KeyboardInterrupt", fixed_do_wait, KeyboardInterrupt())

asyncio.run(main())