os.py 文件源码

def makedirs(name, mode=0o777, exist_ok=False):
    """makedirs(path [, mode=0o777][, exist_ok=False])

    Super-mkdir; create a leaf directory and all intermediate ones.
    Works like mkdir, except that any intermediate path segment (not
    just the rightmost) will be created if it does not exist. If the
    target directory with the same mode as we specified already exists,
    raises an OSError if exist_ok is False, otherwise no exception is
    raised.  This is recursive.

    """
    head, tail = path.split(name)
    if not tail:
        head, tail = path.split(head)
    if head and tail and not path.exists(head):
        try:
            makedirs(head, mode, exist_ok)
        except OSError as e:
            # be happy if someone already created the path
            if e.errno != errno.EEXIST:
                raise
        cdir = curdir
        if isinstance(tail, bytes):
            cdir = bytes(curdir, 'ASCII')
        if tail == cdir:           # xxx/newdir/. exists if xxx/newdir exists
            return
    try:
        mkdir(name, mode)
    except OSError as e:
        dir_exists = path.isdir(name)
        expected_mode = _get_masked_mode(mode)
        if dir_exists:
            # S_ISGID is automatically copied by the OS from parent to child
            # directories on mkdir.  Don't consider it being set to be a mode
            # mismatch as mkdir does not unset it when not specified in mode.
            actual_mode = st.S_IMODE(lstat(name).st_mode) & ~st.S_ISGID
        else:
            actual_mode = -1
        if not (e.errno == errno.EEXIST and exist_ok and dir_exists and
                actual_mode == expected_mode):
            if dir_exists and actual_mode != expected_mode:
                e.strerror += ' (mode %o != expected mode %o)' % (
                        actual_mode, expected_mode)
            raise