shitbox/src/cmd/chroot/mod.rs

use super::Cmd;
use clap::{Arg, Command};
use std::{
    env, io,
    os::unix::{fs, process::CommandExt},
    process,
};

#[derive(Debug, Default)]
pub struct Chroot;

impl Cmd for Chroot {
    fn cli(&self) -> clap::Command {
        Command::new("chroot")
            .about("run command or interactive shell with special root directory")
            .author("Nathan Fisher")
            .version(env!("CARGO_PKG_VERSION"))
            .args([
                Arg::new("dir")
                    .short('d')
                    .long("directory")
                    .help("change to this directory after performing the chroot instead of '/'")
                    .value_name("DIRECTORY"),
                Arg::new("newroot")
                    .value_name("NEWROOT")
                    .num_args(1)
                    .required(true),
                Arg::new("command")
                    .value_name("COMMAND")
                    .num_args(1)
                    .required(false),
                Arg::new("arg")
                    .value_name("ARG")
                    .num_args(1..)
                    .requires("command")
                    .allow_hyphen_values(true)
                    .required(false),
            ])
    }

    fn run(&self, matches: &clap::ArgMatches) -> Result<(), Box<dyn std::error::Error>> {
        let Some(newroot) = matches.get_one::<String>("newroot") else {
            return Err(io::Error::new(io::ErrorKind::Other, "no new root given").into());
        };
        let mut command = if let Some(c) = matches.get_one::<String>("command") {
            process::Command::new(c)
        } else if let Ok(s) = env::var("SHELL") {
            process::Command::new(s)
        } else {
            process::Command::new("/bin/sh")
        };
        let mut command = &mut command;
        if let Some(mut args) = matches.get_many::<String>("arg") {
            command = command.args(&mut args);
        }
        fs::chroot(newroot)?;
        if let Some(d) = matches.get_one::<String>("dir") {
            env::set_current_dir(d)?;
        } else {
            env::set_current_dir("/")?;
        }
        return Err(command.exec().into());
    }

    fn path(&self) -> Option<crate::Path> {
        Some(crate::Path::UsrSbin)
    }
}