feat(userspace): terminal server + shell desktop; US keymap w/ shift; libkos allocator multi-page fix; panics print

crates/apps/shell/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "shell"
+version = "0.1.0"
+edition = "2024"
+
+[[bin]]
+name = "shell"
+test = false
+bench = false
+
+[dependencies]
+types = { workspace = true }
+libkos = { workspace = true }

crates/apps/shell/src/main.rs

@@ -0,0 +1,48 @@
+//! The shell, for now built-ins only; running programs comes next.
+
+#![no_std]
+#![no_main]
+
+extern crate libkos;
+
+use libkos::{print, println};
+use types::bounded::CapSlot;
+
+/// Init's manifest gives it the terminal first.
+const TERMINAL: CapSlot = CapSlot::const_new(0);
+
+fn run(line: &str) {
+    let mut words = line.split_ascii_whitespace();
+    match words.next() {
+        None => {}
+        Some("help") => {
+            println!("built-ins: help, echo <text>, clear");
+        }
+        Some("echo") => {
+            let mut first = true;
+            for w in words {
+                print!("{}{}", if first { "" } else { " " }, w);
+                first = false;
+            }
+            println!();
+        }
+        Some("clear") => libkos::terminal::clear(TERMINAL),
+        Some(other) => println!("shell: {}: not found", other),
+    }
+}
+
+#[unsafe(no_mangle)]
+extern "C" fn main() {
+    // Everything this shell prints goes to the terminal.
+    libkos::start::set_log(Some(TERMINAL));
+    println!("k-os shell. Type 'help'.");
+    let mut buf = [0u8; 256];
+    loop {
+        print!("$ ");
+        let n = libkos::terminal::read_line(TERMINAL, &mut buf);
+        match core::str::from_utf8(&buf[..n]) {
+            Ok(line) => run(line.trim_end_matches('\n')),
+            Err(_) => println!("shell: not text"),
+        }
+    }
+}

crates/apps/snake/src/main.rs

@@ -67,16 +67,17 @@ extern "C" fn main() {
 fn handle_input(snake: &mut Snake) {
     // Drain all pending events, apply the latest direction
     loop {
-        let Ok([tag, kind, _, _]) = syscall::request(DISPLAY_EP, [types::display::input::POLL, 0, 0, 0]) else {
+        let Ok([tag, kind, ch, _]) = syscall::request(DISPLAY_EP, [types::display::input::POLL, 0, 0, 0]) else {
             break;
         };
         if tag == 0 { break; } // NoEvent — queue drained
         if tag == 1 {
-            match kind {
-                0 => snake.set_direction(Direction::Up),
-                1 => snake.set_direction(Direction::Down),
-                2 => snake.set_direction(Direction::Left),
-                3 => snake.set_direction(Direction::Right),
+            // Arrows, or WASD (kind 9 is a character).
+            match (kind, ch as u8) {
+                (0, _) | (9, b'w') => snake.set_direction(Direction::Up),
+                (1, _) | (9, b's') => snake.set_direction(Direction::Down),
+                (2, _) | (9, b'a') => snake.set_direction(Direction::Left),
+                (3, _) | (9, b'd') => snake.set_direction(Direction::Right),
                 _ => {}
             }
         }