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

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"),
+        }
+    }
+}