Re: [PATCH v3 2/2] xl: Add escape character argument to xl console

[Peter Hoyes <Peter.Hoyes@xxxxxxx>]

Thanks for the feedback.

On 10/07/2023 15:43, Anthony PERARD wrote:
> On Thu, Jun 22, 2023 at 03:12:48PM +0100, Peter Hoyes wrote:
> >   /* libxl_primary_console_exec finds the domid and console number
> >    * corresponding to the primary console of the given vm, then calls
> >    * libxl_console_exec with the right arguments (domid might be different
> > @@ -1968,9 +1969,12 @@ int libxl_console_exec(libxl_ctx *ctx, uint32_t domid, 
> > int cons_num,
> >    * guests using pygrub.
> >    * If notify_fd is not -1, xenconsole will write 0x00 to it to nofity
> >    * the caller that it has connected to the guest console.
> > + * If escape_character is not NULL, the provided value is used to exit
> > + * the guest console.
> >    */
> >   int libxl_primary_console_exec(libxl_ctx *ctx, uint32_t domid_vm,
> > -                               int notify_fd);
> > +                               int notify_fd,
> > +                               char* escape_character);
> >   
> >   #if defined(LIBXL_API_VERSION) && LIBXL_API_VERSION < 0x040800
> >   
> > diff --git a/tools/libs/light/libxl_console.c b/tools/libs/light/libxl_console.c
> > index f497be141b..0b7293fe71 100644
> > --- a/tools/libs/light/libxl_console.c
> > +++ b/tools/libs/light/libxl_console.c
> > @@ -75,15 +76,26 @@ int libxl_console_exec(libxl_ctx *ctx, uint32_t domid, int 
> > cons_num,
> >           goto out;
> >       }
> >   
> > +    char *args[] = {
> > +        p, domid_s, "--num", cons_num_s, "--type", cons_type_s,
> > +        NULL, NULL, NULL, NULL, // start-notify-fd, escape
> > +        NULL, // list terminator - do not use
> > +    };
> > +    char **args_extra = args + 6;
> > +
> >       if (notify_fd != -1) {
> >           notify_fd_s = GCSPRINTF("%d", notify_fd);
> > -        execl(p, p, domid_s, "--num", cons_num_s, "--type", cons_type_s,
> > -              "--start-notify-fd", notify_fd_s, (void *)NULL);
> > -    } else {
> > -        execl(p, p, domid_s, "--num", cons_num_s, "--type", cons_type_s,
> > -              (void *)NULL);
> > +        *args_extra++ = "--start-notify-fd";
> > +        *args_extra++ = notify_fd_s;
> >       }
> >   
> > +    if (escape_character) {
> > +        *args_extra++ = "--escape";
> > +        *args_extra++ = escape_character;
> > +    }
> There is flexarray_* that could be use, but I guess a preset `*args`
> kind of work here.
I looked into flexarray but didn't implement in v4 - as it stands, 
libxl_console_exec and libxl_vncviewer_exec are using the same pattern.
Peter