Subject: tools/console: reset tty when xenconsole fails
From: Ian Jackson ian.jackson@eu.citrix.com Mon Feb 24 15:16:19 2014 +0000
Date: Wed Mar 19 13:37:19 2014 +0000:
Git: 111931f36885874103d65685ab15ea3d25d93da7

If xenconsole (the client program) fails, it calls err.  This would
previously neglect to reset the user's terminal to sanity.  Use atexit
to do so.

This routinely happens in Xen 4.4 RC5 with pygrub because libxl
writes the value "" to the tty xenstore key when using xenconsole.
After this patch this just results in a harmless error message.

Reported-by: M A Young <m.a.young@durham.ac.uk>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: M A Young <m.a.young@durham.ac.uk>
CC: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

---
v2: Fix whitespace error (reintroduce hard tab)
    Fix commit message not to claim ignorance about root cause

Index: xen-4.4.0-testing/tools/console/client/main.c
===================================================================
--- xen-4.4.0-testing.orig/tools/console/client/main.c
+++ xen-4.4.0-testing/tools/console/client/main.c
@@ -258,6 +258,13 @@ typedef enum {
        CONSOLE_SERIAL,
 } console_type;
 
+static struct termios stdin_old_attr;
+
+static void restore_term_stdin(void)
+{
+	restore_term(STDIN_FILENO, &stdin_old_attr);
+}
+
 int main(int argc, char **argv)
 {
 	struct termios attr;
@@ -384,9 +391,9 @@ int main(int argc, char **argv)
 	}
 
 	init_term(spty, &attr);
-	init_term(STDIN_FILENO, &attr);
+	init_term(STDIN_FILENO, &stdin_old_attr);
+	atexit(restore_term_stdin); /* if this fails, oh dear */
 	console_loop(spty, xs, path);
-	restore_term(STDIN_FILENO, &attr);
 
 	free(path);
 	free(dom_path);