add cmd line option parser

Cargo.toml

@@ -6,3 +6,4 @@ edition = "2018"
 
 [dependencies]
 nix = "0.11.0"
+getopts = "0.2"

src/main.rs

@@ -2,14 +2,16 @@ use nix::mount::{mount, MsFlags};
 use nix::sched::*; // 調べる
 use nix::sys::wait::*;
 use nix::unistd::*;
-use nix::unistd::*;
-use nix::unistd::{execv, fork, ForkResult};
+// use nix::unistd::{execv, fork, ForkResult};
+use getopts::Options;
 use std::env::{args, set_var};
 use std::ffi::CString;
 use std::fs;
 use std::process::*;
 
-fn print_help() {}
+fn print_help() {
+    println!("help message");
+}
 
 // TODO Bootstrap func
 
@@ -18,13 +20,25 @@ fn main() {
     set_var("RUST_BACKTRACE", "1");
 
     let args: Vec<String> = args().collect();
-    if args.len() < 2 {
-        eprintln!("invalid argments");
+
+    let mut opts = Options::new();
+    opts.optopt("", "path", "set container path", "CONTAINER PATH");
+    opts.optflag("h", "help", "print help message");
+
+    let matches = match opts.parse(&args[1..]) {
+        Ok(m) => m,
+        Err(f) => panic!(f.to_string()),
+    };
+    if matches.opt_present("h") {
         print_help();
-        exit(1);
+        return;
     }
 
-    let container_path = args[1].as_str();
+    let container_path = matches.opt_str("path").unwrap();
+    let container_path = container_path.as_str();
+
+    println!("{:?}", container_path);
+    // let container_path = args[1].as_str();
 
     match unshare(CloneFlags::CLONE_NEWPID | CloneFlags::CLONE_NEWNS) {
         Ok(_) => {}