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

[Lei Li <lilei@linux.vnet.ibm.com>]

On 10/23/2012 02:59 AM, Luiz Capitulino wrote:
> On Mon, 22 Oct 2012 00:48:01 +0800
> Lei Li <lilei@linux.vnet.ibm.com> wrote:
>
>> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
>> ---
>>   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
>> +@item console @var{device}
>> +@findex 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-]'.
>> +@example
>> +(qemu) console foo
>> +foo: data string...
>> +@end 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