sysutils: add tree utility

userspace/sysutils/Cargo.toml

@@ -81,6 +81,10 @@ path = "src/echo.rs"
 name = "ls"
 path = "src/ls.rs"
 
+[[bin]]
+name = "tree"
+path = "src/tree.rs"
+
 [[bin]]
 name = "mv"
 path = "src/mv.rs"

userspace/sysutils/src/tree.rs

@@ -0,0 +1,90 @@
+use std::{
+    fs, io,
+    path::{Path, PathBuf},
+    process::ExitCode,
+};
+
+use clap::Parser;
+
+fn list<P: AsRef<Path>>(path: P, depth: usize, last_mask: u64) -> io::Result<()> {
+    fn indent(depth: usize, mask: u64) {
+        for i in 0..depth + 1 {
+            if i < depth {
+                if (1 << i) & mask == 0 {
+                    print!("│ ");
+                } else {
+                    print!("  ");
+                }
+            } else if (1 << i) & mask == 0 {
+                print!("├─");
+            } else {
+                print!("└─");
+            }
+        }
+    }
+
+    let mut entries = vec![];
+    let dir = fs::read_dir(path)?;
+    for entry in dir {
+        let Ok((ty, entry)) = entry.and_then(|e| Ok((e.file_type()?, e))) else {
+            entries.push(None);
+            continue;
+        };
+
+        let name = entry.file_name().into_string().unwrap();
+
+        if name == "." || name == ".." {
+            continue;
+        }
+
+        entries.push(Some((name, entry.path(), ty.is_dir())));
+    }
+
+    entries.sort_by(|a, b| {
+        let (Some((a, _, _)), Some((b, _, _))) = (a.as_ref(), b.as_ref()) else {
+            return Ord::cmp(&a.is_none(), &b.is_none());
+        };
+
+        Ord::cmp(a, b)
+    });
+
+    let len = entries.len();
+    for (i, entry) in entries.into_iter().enumerate() {
+        let last_bit = ((i == len - 1) as u64) << depth;
+        indent(depth, last_mask | last_bit);
+
+        let Some((name, path, dir)) = entry else {
+            println!("<error>");
+            continue;
+        };
+
+        println!("{name}");
+
+        if dir {
+            list(path, depth + 1, last_mask | last_bit).ok();
+        }
+    }
+
+    Ok(())
+}
+
+#[derive(Debug, Parser)]
+struct Args {
+    path: Option<PathBuf>,
+}
+
+fn run<P: AsRef<Path>>(path: P) -> io::Result<()> {
+    list(path, 0, 0)
+}
+
+fn main() -> ExitCode {
+    let args = Args::parse();
+    let path = args.path.unwrap_or_else(|| PathBuf::from("."));
+    match run(&path) {
+        Ok(()) => ExitCode::SUCCESS,
+        Err(error) => {
+            eprintln!("{}: {}", path.display(), error);
+            ExitCode::FAILURE
+        }
+    }
+}

xtask/src/build/userspace.rs

@@ -58,6 +58,7 @@ const PROGRAMS: &[(&str, &str)] = &[
     ("sysmon", "bin/sysmon"),
     ("top", "bin/top"),
     ("touch", "bin/touch"),
+    ("tree", "bin/tree"),
     ("tst", "bin/tst"),
     ("view", "bin/view"),
     // netutils