how to set read path as root path in xmake project ?

[Fodesu]

i want to read file in project root path when i run xmake run target, but now it can only be read from the build directory;

#include <exception>
#include <fmt/args.h>
#include <fstream>
#include <iostream>
#include <sstream>

int main() {
  std::cout << "hello world" << std::endl;
  std::ifstream file;
  try {
    file.open(".env.local");
    fmt::println("reading file...");
    std::stringstream strstream;
    strstream << file.rdbuf();

    file.close();
    fmt::println("closing file...");
    auto str = strstream.str();
    fmt::println("file content : {}", str);

  } catch (std::exception e) {
    fmt::println(e.what());
  }
}

xmake.lua:

add_rules("mode.debug", "mode.release")
add_rules("plugin.compile_commands.autoupdate")

add_requires("fmt")
add_requires("glfw", "glad", "glm")

on_config(function(target)
	target:add("includedirs", "include")
end)

target("window")
	set_kind("binary")
	add_files("src/main.cpp")
	add_packages("fmt", "glad", "glfw", "glm")

[star-hengxing]

https://xmake.io/#/manual/project_target?id=targetset_rundir