Fix suspend-frame on the controlling tty (reported by Dan Nicolaescu).

* src/term.c (Fdisplay_controlling_tty_p): New function.

* src/term.c (syms_of_term): Initialize Sdisplay_controlling_tty_p.

* lisp/frame.el (suspend-frame): Use display-controlling-tty-p to decide
  between suspend-emacs and suspend-tty.

* src/keyboard.c (Fsuspend_emacs): Give a better error message when
  there are multiple open tty devices.


git-archimport-id: lorentey@elte.hu--2004/emacs--multi-tty--0--patch-213

3 files changed, 21 insertions, 5 deletions

diff --git a/lisp/frame.el b/lisp/frame.el
index 13a1ca50adf..243ad71497d 100644
--- a/lisp/frame.el
+++ b/lisp/frame.el
@@ -788,9 +788,9 @@ Calls `suspend-emacs' if invoked from the controlling terminal,
     (cond
      ((eq type 'x) (iconify-or-deiconify-frame))
      ((eq type t)
-      (if (display-name)
-          (suspend-tty)
-        (suspend-emacs)))
+      (if (display-controlling-tty-p)
+          (suspend-emacs)
+        (suspend-tty)))
      (t (suspend-emacs)))))
 
 
diff --git a/src/keyboard.c b/src/keyboard.c
index 7c1c6f3f463..3fc685d58c7 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -10193,7 +10193,7 @@ On such systems, Emacs starts a subshell instead of suspending.  */)
   struct gcpro gcpro1;
 
   if (tty_list && tty_list->next)
-    error ("Suspend is not supported with multiple ttys");
+    error ("There are other tty frames open; close them before suspending Emacs");
 
   if (!NILP (stuffstring))
     CHECK_STRING (stuffstring);
diff --git a/src/term.c b/src/term.c
index 629c823e8b2..899829ebadb 100644
--- a/src/term.c
+++ b/src/term.c
@@ -2197,7 +2197,6 @@ frame's display). */)
     return Qnil;
 }
 
-
 DEFUN ("display-tty-type", Fdisplay_tty_type, Sdisplay_tty_type, 0, 1, 0,
        doc: /* Return the type of the TTY device that DISPLAY uses. */)
   (display)
@@ -2216,6 +2215,22 @@ DEFUN ("display-tty-type", Fdisplay_tty_type, Sdisplay_tty_type, 0, 1, 0,
     return Qnil;
 }
 
+DEFUN ("display-controlling-tty-p", Fdisplay_controlling_tty_p, Sdisplay_controlling_tty_p, 0, 1, 0,
+       doc: /* Return non-nil if DISPLAY is on the controlling tty of the Emacs process. */)
+  (display)
+     Lisp_Object display;
+{
+  struct display *d = get_display (display);
+
+  if (!d)
+    wrong_type_argument (Qdisplay_live_p, display);
+
+  if (d->type != output_termcap || d->display_info.tty->name)
+    return Qnil;
+  else
+    return Qt;
+}
+
 
 /***********************************************************************
                             Initialization
@@ -3363,6 +3378,7 @@ See `resume-tty'.  */);
   defsubr (&Stty_display_color_cells);
   defsubr (&Sdisplay_name);
   defsubr (&Sdisplay_tty_type);
+  defsubr (&Sdisplay_controlling_tty_p);
   defsubr (&Sdelete_display);
   defsubr (&Sdisplay_live_p);
   defsubr (&Sdisplay_list);