Re: [PATCH v2 02/13] script language API for GDB: extension.[ch]

[Doug Evans <xdje42@gmail.com>]

[+ guile-user, in case they have any thoughts on Guile SIGINT handling]

On Mon, Dec 23, 2013 at 1:57 PM, Tom Tromey <tromey@redhat.com> wrote:
>>>>>> "Doug" == Doug Evans <xdje42@gmail.com> writes:
>
> Doug> +void
> Doug> +clear_quit_flag (void)
> Doug> +{
> Doug> +  int i;
> Doug> +  const struct extension_language_defn *extlang;
> Doug> +
> Doug> +  ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
> Doug> +    {
> Doug> +      if (extlang->ops->clear_quit_flag != NULL)
> Doug> + extlang->ops->clear_quit_flag (extlang);
> Doug> +    }
> Doug> +
> Doug> +  quit_flag = 0;
> Doug> +}
>
> I don't think this will work properly.  It seems to me that a given
> interrupt may be processed multiple times -- once by each extension
> language.

Guile doesn't provide the same hooks that Python does for SIGINT
(PyErr_SetInterrupt, et.al.) so I expect this part to need some work.

> The way it works right now, if Python handles the "quit", then Python
> clears the flag -- which also clears gdb's notion of the flag, because
> the two are identical.
>
> With the above it seems that Python could clear its flag -- but leave
> other extension languages unaware that the interrupt was handled.  So, a
> subsequent call into Guile will presumably erroneously throw an
> exception.

We carefully manage entry and exit to/from extension languages.
It should be possible to manage SIGINT across these boundaries.
v3 coming up, but I'm leaving this part to v4.