From eedf065e6ed6c5867bcb2a22783fe17e9b12b239 Mon Sep 17 00:00:00 2001
From: Amr Gharbeia <amr@gharbeia.net>
Date: Thu, 14 May 2026 14:41:45 -0400
Subject: [PATCH] fix: use :input :inherit for stty size subprocess

:input :inherit preserves the parent's fd 0 (the terminal) in the
child process, so stty can query it via ioctl. Previous approaches
(:input :interactive, /dev/tty) all failed because uiop's process
setup redirects stdin away from the terminal.
---
 src/backend/modern.lisp | 27 +++++++++++++--------------
 src/backend/simple.lisp | 24 ++++++++++++------------
 2 files changed, 25 insertions(+), 26 deletions(-)

diff --git a/src/backend/modern.lisp b/src/backend/modern.lisp
index db4c992..02a7441 100644
--- a/src/backend/modern.lisp
+++ b/src/backend/modern.lisp
@@ -162,21 +162,20 @@ as a fallback when a keyword is not in *named-colors*.")
   (values))
 
 (defmethod backend-size ((b modern-backend))
-  (or ;; tput lines / tput cols via subprocess — most reliable across
-      ;; all systems. Each outputs a single number. Works in any
-      ;; subprocess context, no parsing complexity.
+  (or ;; stty size with :input :inherit — preserves the parent's fd 0
+      ;; (the terminal) so stty can query it via ioctl.
       (multiple-value-bind (cols rows)
-          (values
-            (ignore-errors
-              (parse-integer
-                (string-trim '(#\newline #\space)
-                  (uiop:run-program '("tput" "cols") :output :string
-                                    :ignore-error-status t))))
-            (ignore-errors
-              (parse-integer
-                (string-trim '(#\newline #\space)
-                  (uiop:run-program '("tput" "lines") :output :string
-                                    :ignore-error-status t)))))
+          (ignore-errors
+            (let* ((out (uiop:run-program '("stty" "size") :output :string
+                                          :input :inherit
+                                          :ignore-error-status t))
+                   (parts (and out (uiop:split-string
+                                     (string-trim '(#\newline #\space) out)))))
+              (when (and parts (= (length parts) 2))
+                (let ((r (parse-integer (first parts) :junk-allowed t))
+                      (c (parse-integer (second parts) :junk-allowed t)))
+                  (when (and r c (> r 0) (> c 0))
+                    (values c r))))))
         (when (and cols rows (> cols 0) (> rows 0))
           (values cols rows)))
       ;; ioctl on stdout fd — fast, correct after SIGWINCH at runtime.
diff --git a/src/backend/simple.lisp b/src/backend/simple.lisp
index 3a76769..f67e65d 100644
--- a/src/backend/simple.lisp
+++ b/src/backend/simple.lisp
@@ -22,19 +22,19 @@
   (values))
 
 (defmethod backend-size ((b simple-backend))
-  (or ;; tput cols / tput lines via subprocess
+  (or ;; stty size with :input :inherit — preserves parent's fd 0.
       (multiple-value-bind (cols rows)
-          (values
-            (ignore-errors
-              (parse-integer
-                (string-trim '(#\newline #\space)
-                  (uiop:run-program '("tput" "cols") :output :string
-                                    :ignore-error-status t))))
-            (ignore-errors
-              (parse-integer
-                (string-trim '(#\newline #\space)
-                  (uiop:run-program '("tput" "lines") :output :string
-                                    :ignore-error-status t)))))
+          (ignore-errors
+            (let* ((out (uiop:run-program '("stty" "size") :output :string
+                                          :input :inherit
+                                          :ignore-error-status t))
+                   (parts (and out (uiop:split-string
+                                     (string-trim '(#\newline #\space) out)))))
+              (when (and parts (= (length parts) 2))
+                (let ((r (parse-integer (first parts) :junk-allowed t))
+                      (c (parse-integer (second parts) :junk-allowed t)))
+                  (when (and r c (> r 0) (> c 0))
+                    (values c r))))))
         (when (and cols rows (> cols 0) (> rows 0))
           (values cols rows)))
       ;; ioctl on stdout fd — fast, correct after SIGWINCH at runtime.