_daemonize_unix.py 文件源码

def _autoclose_files(shielded=None, fallback_limit=1024):
    ''' Automatically close any open file descriptors.

    shielded is iterable of file descriptors.
    '''
    # Process shielded.
    shielded = default_to(shielded, [])

    # Figure out the maximum number of files to try to close.
    # This returns a tuple of softlimit, hardlimit; the hardlimit is always
    # greater.
    softlimit, hardlimit = resource.getrlimit(resource.RLIMIT_NOFILE)

    # If the hard limit is infinity, we can't iterate to it.
    if hardlimit == resource.RLIM_INFINITY:
        # Check the soft limit. If it's also infinity, fallback to guess.
        if softlimit == resource.RLIM_INFINITY:
            fdlimit = fallback_limit

        # The soft limit is finite, so fallback to that.
        else:
            fdlimit = softlimit

    # The hard limit is not infinity, so prefer it.
    else:
        fdlimit = hardlimit

    # Skip fd 0, 1, 2, which are used by stdin, stdout, and stderr
    # (respectively)
    ranges_to_close = _make_range_tuples(
        start = 3,
        stop = fdlimit,
        exclude = shielded
    )
    for start, stop in ranges_to_close:
        # How nice of os to include this for us!
        os.closerange(start, stop)