Re: [Qemu-devel] [PATCH 5/5] HMP: Introduce console command

[Lei Li]

On 10/23/2012 02:59 AM, Luiz Capitulino wrote:
> On Mon, 22 Oct 2012 00:48:01 +0800
> Lei Li <address@hidden> wrote:
>
> > Signed-off-by: Lei Li <address@hidden>
> > ---
> >   hmp-commands.hx |   23 +++++++++++++++++++++++
> >   hmp.c           |   53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> >   hmp.h           |    1 +
> >   monitor.c       |   15 +++++++++++++++
> >   monitor.h       |    3 +++
> >   5 files changed, 95 insertions(+), 0 deletions(-)
> >
> > diff --git a/hmp-commands.hx b/hmp-commands.hx
> > index 5f91428..f862a53 100644
> > --- a/hmp-commands.hx
> > +++ b/hmp-commands.hx
> > @@ -868,7 +868,30 @@ char device and return @var{size} of the data.
> >   that specifies behavior when the queue is full/empty. By default is
> >   'drop'. Note that the 'block' option is not supported now.
> >           -b for 'block' option. None for 'drop' option.
> > +ETEXI
> > +
> > +    {
> > +        .name       = "console",
> > +        .args_type  = "chardev:s",
> > +        .params     = "chardev",
> > +        .help       = "Connect to the serial console from within the"
> > +                      "monitor, allow to write data to memchardev"
> > +                      "'chardev'. Exit from the console and return back"
> > +                      "to monitor by typing 'ctrl-]'",
> > +        .mhandler.cmd = hmp_console,
> > +    },
> >   
> > +STEXI
> > address@hidden console @var{device}
> > address@hidden console
> > +
> > +Connect to the serial console from within the monitor, allow to write data
> > +to memchardev @var{chardev}. Exit from the console and return back to
> > +monitor by typing 'ctrl-]'.
> > address@hidden
> > +(qemu) console foo
> > +foo: data string...
> > address@hidden example
> >   ETEXI
> >   
> >       {
> > diff --git a/hmp.c b/hmp.c
> > index fa858c4..bc245f4 100644
> > --- a/hmp.c
> > +++ b/hmp.c
> > @@ -1245,3 +1245,56 @@ void hmp_screen_dump(Monitor *mon, const QDict *qdict)
> >       qmp_screendump(filename, &err);
> >       hmp_handle_error(mon, &err);
> >   }
> > +
> > +enum escape_char
> > +{
> > +    ESCAPE_CHAR_CTRL_GS = 0x1d  /* ctrl-] used for escape */
> > +};
> > +
> > +static void hmp_read_console(Monitor *mon, const char *data,
> > +                             void *opaque)
> > +{
> > +    CharDriverState *chr = opaque;
> > +    uint32_t size = strlen(data);
> > +    enum DataFormat format = DATA_FORMAT_UTF8;
> > +    enum CongestionControl control = CONGESTION_CONTROL_DROP;
> > +    enum escape_char console_escape = ESCAPE_CHAR_CTRL_GS;
> > +
> > +    Error *err = NULL;
> > +
> > +    if (*data == console_escape) {
> > +        monitor_resume(mon);
> > +        return;
> > +    }
> > +
> > +    qmp_memchar_write(chr->label, size, data, 0, format,
> > +                      0, control, &err);
> > +    if (err) {
> > +        monitor_printf(mon, "%s\n", error_get_pretty(err));
> > +        error_free(err);
> > +        return;
> > +    }
> Shouldn't you also read from the device?

The use-case for this console command is just allow the user to
write data to each memchar device as in a signal terminal. Then
type escape sequences to take you back to the monitor. So I don't
think it is also need to read from the device in this command.

BTW, we can read from the device by hmp_memchar_read. :)

> > +
> > +    monitor_read_command(mon, 1);
> > +}
> > +
> > +void hmp_console(Monitor *mon, const QDict *qdict)
> > +{
> > +    const char *device = qdict_get_str(qdict, "chardev");
> > +    CharDriverState *chr;
> > +    Error *err = NULL;
> > +
> > +    chr = qemu_chr_find(device);
> > +
> > +    if (!chr) {
> > +        error_set(&err, QERR_DEVICE_NOT_FOUND, device);
> > +        goto out;
> > +    }
> No need to do this here as the QMP command will do it too.
I think we should do this check here, otherwise would
cause core dump when 'console' to a chardev that does not
exist. Wepass parameterchr->label by qmp_memchar_write()
in the handler hmp_read_console.

> > +
> > +    if (monitor_read_console(mon, device, hmp_read_console, chr) < 0) {
> > +        monitor_printf(mon, "Connect to console %s failed\n", device);
> > +    }
> > +
> > +out:
> > +    hmp_handle_error(mon, &err);
> > +}
> > diff --git a/hmp.h b/hmp.h
> > index a5a0cfe..5b54a79 100644
> > --- a/hmp.h
> > +++ b/hmp.h
> > @@ -77,5 +77,6 @@ void hmp_getfd(Monitor *mon, const QDict *qdict);
> >   void hmp_closefd(Monitor *mon, const QDict *qdict);
> >   void hmp_send_key(Monitor *mon, const QDict *qdict);
> >   void hmp_screen_dump(Monitor *mon, const QDict *qdict);
> > +void hmp_console(Monitor *mon, const QDict *qdict);
> >   
> >   #endif
> > diff --git a/monitor.c b/monitor.c
> > index 131b325..453c084 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -256,6 +256,21 @@ int monitor_read_password(Monitor *mon, ReadLineFunc 
> > *readline_func,
> >       }
> >   }
> >   
> > +int monitor_read_console(Monitor *mon, const char *device,
> > +                         ReadLineFunc *readline_func, void *opaque)
> > +{
> > +    char prompt[60];
> > +
> > +    if (!mon->rs) {
> > +        return -1;
> > +    }
> > +
> > +    snprintf(prompt, sizeof(prompt), "%s: ", device);
> > +    readline_start(mon->rs, prompt, 0, readline_func, opaque);
> > +
> > +    return 0;
> > +}
> > +
> >   void monitor_flush(Monitor *mon)
> >   {
> >       if (mon && mon->outbuf_index != 0 && !mon->mux_out) {
> > diff --git a/monitor.h b/monitor.h
> > index b6e7d95..735bd1b 100644
> > --- a/monitor.h
> > +++ b/monitor.h
> > @@ -86,6 +86,9 @@ ReadLineState *monitor_get_rs(Monitor *mon);
> >   int monitor_read_password(Monitor *mon, ReadLineFunc *readline_func,
> >                             void *opaque);
> >   
> > +int monitor_read_console(Monitor *mon, const char *device,
> > +                         ReadLineFunc *readline_func, void *opaque);
> > +
> >   int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret);
> >   
> >   int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret);


--
Lei