* tui/tui-interp.c (tui_is_toplevel): New.

(tui_init): Set it.
	(tui_allowed_p): New.
	* tui/tui.c (tui_enable): Check if the TUI is allowed before
	enabling it.
	* tui/tui.h (tui_allowed_p): Declare.

gdb/ChangeLog

@@ -1,3 +1,12 @@
+2010-03-30  Pedro Alves  <pedro@codesourcery.com>
+
+	* tui/tui-interp.c (tui_is_toplevel): New.
+	(tui_init): Set it.
+	(tui_allowed_p): New.
+	* tui/tui.c (tui_enable): Check if the TUI is allowed before
+	enabling it.
+	* tui/tui.h (tui_allowed_p): Declare.
+
 2010-03-30  Ozkan Sezer  <sezeroz@gmail.com>
 
 	* serial.h: Include winsock2.h before windows.h.

gdb/tui/tui-interp.c

@@ -45,11 +45,16 @@ tui_exit (void)
   tui_disable ();
 }
 
+/* True if TUI is the top-level interpreter.  */
+static int tui_is_toplevel = 0;
+
 /* These implement the TUI interpreter.  */
 
 static void *
 tui_init (int top_level)
 {
+  tui_is_toplevel = top_level;
+
   /* Install exit handler to leave the screen in a good shape.  */
   atexit (tui_exit);
 
@@ -63,6 +68,18 @@ tui_init (int top_level)
   return NULL;
 }
 
+/* True if enabling the TUI is allowed.  Example, if the top level
+   interpreter is MI, enabling curses will certainly lose.  */
+
+int
+tui_allowed_p (void)
+{
+  /* Only if TUI is the top level interpreter.  Also don't try to
+     setup curses (and print funny control characters) if we're not
+     outputting to a terminal.  */
+  return tui_is_toplevel && ui_file_isatty (gdb_stdout);
+}
+
 static int
 tui_resume (void *data)
 {

gdb/tui/tui.c

@@ -364,6 +364,9 @@ tui_initialize_readline (void)
 void
 tui_enable (void)
 {
+  if (!tui_allowed_p ())
+    error (_("TUI mode not allowed"));
+
   if (tui_active)
     return;
 

gdb/tui/tui.h

@@ -65,6 +65,10 @@ extern int tui_get_command_dimension (unsigned int *width,
    key shortcut.  */
 extern void tui_initialize_readline (void);
 
+/* True if enabling the TUI is allowed.  Example, if the top level
+   interpreter is MI, enabling curses will certainly lose.  */
+extern int tui_allowed_p (void);
+
 /* Enter in the tui mode (curses).  */
 extern void tui_enable (void);