2 files changed, 10 insertions(+), 4 deletions(-)

M guix/build/syscalls.scm
M tests/syscalls.scm

@@ 915,10 915,12 @@ always a positive integer."
 
   (catch 'system-error
     (lambda ()
-      (match (window-size-columns (terminal-window-size port))
-        ;; Things like Emacs shell-mode return 0, which is unreasonable.
-        (0 (fall-back))
-        ((? number? columns) columns)))
+      (if (file-port? port)
+          (match (window-size-columns (terminal-window-size port))
+            ;; Things like Emacs shell-mode return 0, which is unreasonable.
+            (0 (fall-back))
+            ((? number? columns) columns))
+          (fall-back)))
     (lambda args
       (let ((errno (system-error-errno args)))
         (if (= errno ENOTTY)

@@ 257,4 257,8 @@
 (test-assert "terminal-columns"
   (> (terminal-columns) 0))
 
+(test-assert "terminal-columns non-file port"
+  (> (terminal-columns (open-input-string "Join us now, share the software!"))
+     0))
+
 (test-end)