Shell wrapper for terminal raw mode, demo no longer sets raw mode

Added ./demo shell script that sets raw mode via stty before running
the Lisp demo and restores it on exit (including SIGINT/SIGTERM).

demo.lisp no longer attempts to set raw mode from inside SBCL —
terminal raw mode is the shell's responsibility.  This avoids the
recurring problem of sb-ext:run-program + stty not being able to
access the controlling terminal from inside sbcl --script.

demo

@@ -0,0 +1,20 @@
+#!/bin/sh
+# cl-tty demo launcher
+# Sets raw terminal mode, runs the demo, restores terminal on exit.
+# This is needed because SBCL's --script mode + run-program combo
+# can't reliably set raw mode from inside the Lisp process.
+
+SAVED=$(stty -g 2>/dev/null)
+if [ -z "$SAVED" ]; then
+    echo "ERROR: Not running in a real terminal." >&2
+    echo "       Try: sbcl --script demo.lisp" >&2
+    exit 1
+fi
+
+cleanup() {
+    stty "$SAVED" 2>/dev/null
+}
+trap cleanup EXIT INT TERM
+
+stty raw -echo -isig -icanon min 1 time 0 2>/dev/null
+sbcl --script "$(dirname "$0")/demo.lisp"

demo.lisp

@@ -124,17 +124,14 @@
      t)))
 
 (defun run-demo ()
-  (let ((saved (ignore-errors (set-raw-mode))))
+  "Run the demo.  Assumes raw terminal mode is already set by the
-    (unless saved
+shell wrapper (./demo) or by running:
-      (format *error-output* "~&ERROR: Cannot set terminal to raw mode.~%")
+  stty raw -echo -isig -icanon min 1 time 0
-      (format *error-output* "       Make sure you are in a real terminal (not a pipe/redirect).~%")
+  sbcl --script demo.lisp"
-      (format *error-output* "       Try: sbcl --script demo.lisp~%")
-      (return-from run-demo))
-    (unwind-protect
-         (progn
   (init-app-state)
   (let* ((backend (detect-backend))
          (w 80) (h 24))
+    (declare (ignore h))
     (initialize-backend backend)
     (unwind-protect
          (loop while (getf *app* :running)
@@ -176,8 +173,6 @@
                  (when event
                    (handle-event event))))
       (shutdown-backend backend))))
-      (when saved
-        (restore-terminal-state saved)))))
 
 (run-demo)
 (uiop:quit 0)