Add `chroot` applet

README.md

@@ -24,6 +24,7 @@ code between applets, making for an overall smaller binary.
 - chgrp
 - chmod
 - chown
+- chroot
 - clear
 - cut
 - dirname
@@ -35,6 +36,7 @@ code between applets, making for an overall smaller binary.
 - head
 - hostname
 - link
+- logname
 - mkfifo
 - mknod
 - mountpoint

src/cmd/chroot/mod.rs

@@ -0,0 +1,71 @@
+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: Option<&clap::ArgMatches>) -> Result<(), Box<dyn std::error::Error>> {
+        let Some(matches) = matches else {
+            return Err(io::Error::new(io::ErrorKind::Other, "no input").into());
+        };
+        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)
+    }
+}

src/cmd/mod.rs

@@ -8,6 +8,7 @@ mod bootstrap;
 mod cat;
 mod chmod;
 mod chown;
+mod chroot;
 mod clear;
 mod cp;
 mod cut;
@@ -72,6 +73,7 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
         "chmod" => Some(Box::new(chmod::Chmod::default())),
         "chgrp" => Some(Box::new(chown::Chgrp::default())),
         "chown" => Some(Box::new(chown::Chown::default())),
+        "chroot" => Some(Box::new(chroot::Chroot::default())),
         "clear" => Some(Box::new(clear::Clear::default())),
         "cut" => Some(Box::new(cut::Cut::default())),
         "dirname" => Some(Box::new(dirname::Dirname::default())),
@@ -105,7 +107,7 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
     }
 }
 
-pub static COMMANDS: [&str; 37] = [
+pub static COMMANDS: [&str; 38] = [
     "base32",
     "base64",
     "basename",
@@ -113,6 +115,7 @@ pub static COMMANDS: [&str; 37] = [
     "chgrp",
     "chmod",
     "chown",
+    "chroot",
     "clear",
     "cut",
     "dirname",