char *
ngx_conf_set_path_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    char  *p = conf;

    ssize_t      level;
    ngx_str_t   *value;
    ngx_uint_t   i, n;
    ngx_path_t  *path, **slot;

    slot = (ngx_path_t **) (p + cmd->offset);

    if (*slot) {
        return "is duplicate";
    }

    path = ngx_pcalloc(cf->pool, sizeof(ngx_path_t));
    if (path == NULL) {
        return NGX_CONF_ERROR;
    }

    value = cf->args->elts;

    path->name = value[1];

    if (path->name.data[path->name.len - 1] == '/') {
        path->name.len--;
    }

    if (ngx_conf_full_name(cf->cycle, &path->name, 0) != NGX_OK) {
        return NULL;
    }

    path->len = 0;
    path->manager = NULL;
    path->loader = NULL;
    path->conf_file = cf->conf_file->file.name.data;
    path->line = cf->conf_file->line;

    for (i = 0, n = 2; n < cf->args->nelts; i++, n++) {
        level = ngx_atoi(value[n].data, value[n].len);
        if (level == NGX_ERROR || level == 0) {
            return "invalid value";
        }

        path->level[i] = level;
        path->len += level + 1;
    }

    while (i < 3) {
        path->level[i++] = 0;
    }

    *slot = path;

    if (ngx_add_path(cf, slot) == NGX_ERROR) {
        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}