tempfile.py 文件源码

def mktemp(suffix="", prefix=template, dir=None):
    """User-callable function to return a unique temporary file name.  The
    file is not created.

    Arguments are similar to mkstemp, except that the 'text' argument is
    not accepted, and suffix=None, prefix=None and bytes file names are not
    supported.

    THIS FUNCTION IS UNSAFE AND SHOULD NOT BE USED.  The file name may
    refer to a file that did not exist at some point, but by the time
    you get around to creating it, someone else may have beaten you to
    the punch.
    """

##    from warnings import warn as _warn
##    _warn("mktemp is a potential security risk to your program",
##          RuntimeWarning, stacklevel=2)

    if dir is None:
        dir = gettempdir()

    names = _get_candidate_names()
    for seq in range(TMP_MAX):
        name = next(names)
        file = _os.path.join(dir, prefix + name + suffix)
        if not _exists(file):
            return file

    raise FileExistsError(_errno.EEXIST,
                          "No usable temporary filename found")