Add `readlink` applet

README.md

@@ -45,6 +45,7 @@ code between applets, making for an overall smaller binary.
 - printenv
 - pwd
 - readlink
+- realpath
 - rev
 - rm
 - rmdir

src/cmd/mod.rs

@@ -35,6 +35,7 @@ mod nologin;
 mod nproc;
 mod printenv;
 mod pwd;
+mod readlink;
 mod realpath;
 mod rev;
 mod rm;
@@ -93,6 +94,7 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
         "nproc" => Some(Box::new(nproc::Nproc::default())),
         "printenv" => Some(Box::new(printenv::Printenv::default())),
         "pwd" => Some(Box::new(pwd::Pwd::default())),
+        "readlink" => Some(Box::new(readlink::Readlink::default())),
         "realpath" => Some(Box::new(realpath::Realpath::default())),
         "rev" => Some(Box::new(rev::Rev::default())),
         "rm" => Some(Box::new(rm::Rm::default())),
@@ -109,7 +111,7 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
     }
 }
 
-pub static COMMANDS: [&str; 39] = [
+pub static COMMANDS: [&str; 40] = [
     "base32",
     "base64",
     "basename",
@@ -137,6 +139,7 @@ pub static COMMANDS: [&str; 39] = [
     "nproc",
     "printenv",
     "pwd",
+    "readlink",
     "realpath",
     "rev",
     "rm",

src/cmd/readlink/mod.rs

@@ -0,0 +1,62 @@
+use crate::Cmd;
+use clap::{Arg, ArgAction, ArgMatches, Command, ValueHint};
+use std::{fs, io, path::PathBuf};
+
+#[derive(Debug, Default)]
+pub struct Readlink;
+
+impl Cmd for Readlink {
+    fn cli(&self) -> clap::Command {
+        Command::new("readlink")
+            .about("Print symbolic link target or canonical file name")
+            .version(env!("CARGO_PKG_VERSION"))
+            .author("Nathan Fisher")
+            .args([
+                Arg::new("path")
+                    .value_name("PATH")
+                    .value_hint(ValueHint::AnyPath)
+                    .num_args(1..)
+                    .required(true),
+                Arg::new("canon")
+                    .help("Canonicalize path")
+                    .short('f')
+                    .visible_short_alias('c')
+                    .long("canonicalize")
+                    .action(ArgAction::SetTrue),
+                Arg::new("newline")
+                    .help("Do not print the terminating newline.")
+                    .short('n')
+                    .long("no-newline")
+                    .action(ArgAction::SetTrue),
+            ])
+    }
+
+    fn run(&self, matches: Option<&ArgMatches>) -> Result<(), Box<dyn std::error::Error>> {
+        let Some(matches) = matches else {
+            return Err(io::Error::new(io::ErrorKind::Other, "no input").into());
+        };
+        if let Some(paths) = matches.get_many::<String>("path") {
+            let paths: Vec<_> = paths.collect();
+            let len = paths.len();
+            if matches.get_flag("newline") && len > 1 {
+                eprintln!("readlink: ignoring --no-newline with multiple arguments");
+            }
+            for p in paths {
+                let path = if matches.get_flag("canon") {
+                    PathBuf::from(p).canonicalize()?
+                } else {
+                    fs::read_link(p)?
+                };
+                print!("{}", path.display());
+                if !matches.get_flag("newline") || len > 1 {
+                    println!();
+                }
+            }
+        }
+        Ok(())
+    }
+
+    fn path(&self) -> Option<crate::Path> {
+        Some(crate::Path::UsrBin)
+    }
+}