Rename/Replace function behind "os.replace" in Python 3

replace.c

static PyObject *
internal_rename(PyObject *args, PyObject *kwargs, int is_replace)
{
    char *function_name = is_replace ? "replace" : "rename";
    path_t src;
    path_t dst;
    int src_dir_fd = DEFAULT_DIR_FD;
    int dst_dir_fd = DEFAULT_DIR_FD;
    int dir_fd_specified;
    PyObject *return_value = NULL;
    char format[24];
    static char *keywords[] = {"src", "dst", "src_dir_fd", "dst_dir_fd", NULL};

#ifdef MS_WINDOWS
    BOOL result;
    int flags = is_replace ? MOVEFILE_REPLACE_EXISTING : 0;
#else
    int result;
#endif

    memset(&src, 0, sizeof(src));
    memset(&dst, 0, sizeof(dst));
    src.function_name = function_name;
    dst.function_name = function_name;
    strcpy(format, "O&O&|$O&O&:");
    strcat(format, function_name);
    if (!PyArg_ParseTupleAndKeywords(args, kwargs, format, keywords,
        path_converter, &src,
        path_converter, &dst,
        dir_fd_converter, &src_dir_fd,
        dir_fd_converter, &dst_dir_fd))
        return NULL;

    dir_fd_specified = (src_dir_fd != DEFAULT_DIR_FD) ||
                       (dst_dir_fd != DEFAULT_DIR_FD);
#ifndef HAVE_RENAMEAT
    if (dir_fd_specified) {
        argument_unavailable_error(function_name, "src_dir_fd and dst_dir_fd");
        goto exit;
    }
#endif

    if ((src.narrow && dst.wide) || (src.wide && dst.narrow)) {
        PyErr_Format(PyExc_ValueError,
                     "%s: src and dst must be the same type", function_name);
        goto exit;
    }

#ifdef MS_WINDOWS
    Py_BEGIN_ALLOW_THREADS
    if (src.wide)
        result = MoveFileExW(src.wide, dst.wide, flags);
    else
        result = MoveFileExA(src.narrow, dst.narrow, flags);
    Py_END_ALLOW_THREADS

    if (!result) {
        return_value = path_error2(&src, &dst);
        goto exit;
    }

#else
    Py_BEGIN_ALLOW_THREADS
#ifdef HAVE_RENAMEAT
    if (dir_fd_specified)
        result = renameat(src_dir_fd, src.narrow, dst_dir_fd, dst.narrow);
    else
#endif
        result = rename(src.narrow, dst.narrow);
    Py_END_ALLOW_THREADS

    if (result) {
        return_value = path_error2(&src, &dst);
        goto exit;
    }
#endif

    Py_INCREF(Py_None);
    return_value = Py_None;
exit:
    path_cleanup(&src);
    path_cleanup(&dst);
    return return_value;
}