signal.py 文件源码

def getsignal(signalnum):
    """
    Exactly the same as :func:`signal.signal` except where
    :const:`signal.SIGCHLD` is concerned.

    For :const:`signal.SIGCHLD`, this cooperates with :func:`signal`
    to provide consistent answers.
    """
    if signalnum != _signal.SIGCHLD:
        return _signal_getsignal(signalnum)

    global _child_handler
    if _child_handler is _INITIAL:
        _child_handler = _signal_getsignal(_signal.SIGCHLD)

    return _child_handler