feat: add get root dir from current dir

benchmark/src/main.rs

+use std::path::{Path, PathBuf};
+use std::env;
+use std::ffi::OsStr;
+
 fn main() {
     println!("Hello, world!");
+    let target_dir = get_target_dir();
+    let root_dir = get_top_dir(&*target_dir);
+    println!("{:?}", root_dir);
+}
+
+// https://github.com/rust-lang/cargo/issues/2841
+fn get_target_dir() -> PathBuf {
+    let bin = env::current_exe().expect("exe path");
+    let mut target_dir = PathBuf::from(bin.parent().expect("bin parent"));
+    while target_dir.file_name() != Some(OsStr::new("target")) {
+        target_dir.pop();
+    }
+    target_dir
+}
+
+fn get_top_dir<'a>(target_dir: &'a Path) -> &'a Path {
+    target_dir.parent().expect("target parent")
 }