Re: [Qemu-devel] [PATCH qom-next 3/4] qom: Implement qom-get HMP command

[Hani Benhabiles <kroosec@gmail.com>]

On Thu, May 08, 2014 at 04:21:16PM +0200, Andreas Färber wrote:
> Reimplement it based on qmp_qom_get() to avoid converting QObjects back
> to strings.
> 
> Inspired-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Andreas Färber <afaerber@suse.de>
> ---
>  hmp-commands.hx | 13 +++++++++++++
>  hmp.c           | 22 ++++++++++++++++++++++
>  hmp.h           |  1 +
>  3 files changed, 36 insertions(+)
> 
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index a0166af..c0603e9 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -1691,6 +1691,19 @@ Print QOM properties of object at location @var{path}
>  ETEXI
>  
>      {
> +        .name       = "qom-get",
> +        .args_type  = "path:s,property:s",
> +        .params     = "path property",
> +        .help       = "print QOM property",
> +        .mhandler.cmd  = hmp_qom_get,
> +    },
> +
> +STEXI
> +@item qom-get @var{path} @var{property}
> +Print QOM property @var{property} of object at location @var{path}
> +ETEXI
> +
> +    {
>          .name       = "info",
>          .args_type  = "item:s?",
>          .params     = "[subcommand]",
> diff --git a/hmp.c b/hmp.c
> index 1c29c8a..d7d7a98 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -1693,3 +1693,25 @@ void hmp_qom_list(Monitor *mon, const QDict *qdict)
>      }
>      hmp_handle_error(mon, &err);
>  }
> +
> +void hmp_qom_get(Monitor *mon, const QDict *qdict)
> +{
> +    const char *path = qdict_get_str(qdict, "path");
> +    const char *property = qdict_get_str(qdict, "property");
> +    Error *err = NULL;
> +    Object *obj;
> +    char *value;
> +
> +    obj = object_resolve_path(path, NULL);
> +    if (obj == NULL) {
> +        error_set(&err, QERR_DEVICE_NOT_FOUND, path);
> +        hmp_handle_error(mon, &err);
> +        return;
> +    }
> +    value = object_property_print(obj, property, true, &err);
> +    if (err == NULL) {
> +        monitor_printf(mon, "%s\n", value);
> +        g_free(value);
> +    }
> +    hmp_handle_error(mon, &err);
> +}
> diff --git a/hmp.h b/hmp.h
> index 7ab969e..269d99e 100644
> --- a/hmp.h
> +++ b/hmp.h
> @@ -94,6 +94,7 @@ void hmp_cpu_add(Monitor *mon, const QDict *qdict);
>  void hmp_object_add(Monitor *mon, const QDict *qdict);
>  void hmp_object_del(Monitor *mon, const QDict *qdict);
>  void hmp_qom_list(Monitor *mon, const QDict *qdict);
> +void hmp_qom_get(Monitor *mon, const QDict *qdict);
>  void object_add_completion(ReadLineState *rs, int nb_args, const char *str);
>  void object_del_completion(ReadLineState *rs, int nb_args, const char *str);
>  void device_add_completion(ReadLineState *rs, int nb_args, const char *str);

This segfaults:
(qemu) qom-get /machine/unattached/device[9] date
Segmentation fault (core dumped)

And so does
(qemu) qom-get /machine/unattached/device[0] filtered-features
Segmentation fault (core dumped)

See: https://lists.gnu.org/archive/html/qemu-devel/2014-05/msg01975.html