Re: [Xen-devel] [PATCH 1/2] tools/console: reset tty when xenconsole fails

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 03/17/2014 04:24 PM, Ian Jackson wrote:
> 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 something
> writes the value "" to the tty xenstore key when using xenconsole.
> The cause of this is not yet known, but after this patch it just
> results in a harmless error message.
Is it the case that the cause of this is still not yet known?  It seemed 
to be explained by the subsequent patch. :-)
In any case:

Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

> Reported-by: M A Young <m.a.young@xxxxxxxxxxxx>
> Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: M A Young <m.a.young@xxxxxxxxxxxx>
> CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
> CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> ---
>   tools/console/client/main.c |   11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/tools/console/client/main.c b/tools/console/client/main.c
> index eb6a1a9..62159f6 100644
> --- a/tools/console/client/main.c
> +++ b/tools/console/client/main.c
> @@ -257,6 +257,13 @@ 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;
> @@ -383,9 +390,9 @@ 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);

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