Add login process. Remove debugging. Fix order of arguments

programs/login/src/main.rs

@@ -0,0 +1,38 @@
+extern crate syscall;
+
+use std::env;
+use std::process::Command;
+use std::thread;
+
+pub fn main() {
+    let mut args = env::args().skip(1);
+
+    let tty = args.next().expect("login: no tty provided");
+    let sh = args.next().expect("login: no sh provided");
+    let sh_args: Vec<String> = args.collect();
+
+    syscall::close(2);
+    syscall::close(1);
+    syscall::close(0);
+
+    syscall::open(&tty, syscall::flag::O_RDWR);
+    syscall::open(&tty, syscall::flag::O_RDWR);
+    syscall::open(&tty, syscall::flag::O_RDWR);
+
+    thread::spawn(move || {
+        loop {
+            let mut command = Command::new(&sh);
+            for arg in sh_args.iter() {
+                command.arg(arg);
+            }
+
+            match command.spawn() {
+                Ok(mut child) => match child.wait() {
+                    Ok(_status) => (), //println!("login: waited for {}: {:?}", sh, status.code()),
+                    Err(err) => panic!("login: failed to wait for '{}': {}", sh, err)
+                },
+                Err(err) => panic!("login: failed to execute '{}': {}", sh, err)
+            }
+        }
+    });
+}