Re: [Qemu-devel] [PATCH 12/13] qapi: support for keyworded variable-length argument list

[Anthony Liguori <aliguori@us.ibm.com>]

On 03/29/2012 12:26 PM, Luiz Capitulino wrote:
> This allows for QAPI functions to receive a variable-length argument
> list. This is going to be used by device_add and netdev_add commands.
>
> In the schema, the argument list is represented by type name '**',
> like this example:
>
>      { 'command': 'foo', 'data': { 'arg-list': '**' } }
>
> Each argument is represented by the KeyValues type and the C
> implementation should expect a KeyValuesList, like:
>
>      void qmp_foo(KeyValuesList *values_list, Error **errp);
>
> XXX: This implementation is simple but very hacky. We just iterate
>       through all arguments and build the KeyValuesList list to be
>       passed to the QAPI function.
>
>       Maybe we could have a kwargs type, that does exactly this but
>       through a visitor instead?
>
> Signed-off-by: Luiz Capitulino<lcapitulino@redhat.com>

What about just treating '**' as "marshal remaining arguments to a string" and 
then pass that string to device_add?  qmp_device_add can then parse that string 
with QemuOpts.

It's a bit ugly, but that's how things worked.  When we introduce qom_add, this 
problem goes away because you would make multiple calls to qom_set to set all of 
the properties.

Regards,

Anthony Liguori

> ---
>   qapi-schema.json         |   15 +++++++++++++++
>   scripts/qapi-commands.py |   31 ++++++++++++++++++++++++++++---
>   scripts/qapi.py          |    2 ++
>   3 files changed, 45 insertions(+), 3 deletions(-)
>
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 0d11d6e..25bd487 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -1701,3 +1701,18 @@
>   # Since: 1.1
>   ##
>   { 'command': 'xen-save-devices-state', 'data': {'filename': 'str'} }
> +
> +##
> +# @KeyValues:
> +#
> +# A generic representation of a key value pair.
> +#
> +# @key: the name of the item
> +#
> +# @value: the string representation of the item value.  This typically follows
> +#         QEMU's command line parsing format.  See the man pages for more
> +#         information.
> +#
> +# Since: 0.14.0
> +##
> +{ 'type': 'KeyValues', 'data': {'key': 'str', 'value': 'str'} }
> diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
> index 30a24d2..75a6e81 100644
> --- a/scripts/qapi-commands.py
> +++ b/scripts/qapi-commands.py
> @@ -146,19 +146,44 @@ v = qmp_input_get_visitor(mi);
>                        obj=obj)
>
>       for argname, argtype, optional, structured in parse_args(args):
> -        if optional:
> +        if optional and not '**':
>               ret += mcgen('''
>   visit_start_optional(v,&has_%(c_name)s, "%(name)s", errp);
>   if (has_%(c_name)s) {
>   ''',
>                            c_name=c_var(argname), name=argname)
>               push_indent()
> -        ret += mcgen('''
> +        if argtype == '**':
> +            if dealloc:
> +                ret += mcgen('''
> +qapi_free_KeyValuesList(%(obj)s);
> +''',
> +                        obj=c_var(argname))
> +            else:
> +                ret += mcgen('''
> +{
> +    const QDictEntry *entry;
> +    v = v; /* fix me baby */
> +
> +    for (entry = qdict_first(args); entry; entry = qdict_next(qdict, entry)) {
> +        KeyValuesList *item = g_malloc0(sizeof(*item));
> +        item->value = g_malloc0(sizeof(*item->value));
> +        item->value->key = g_strdup(qdict_entry_key(entry));
> +        item->value->value = g_strdup(qstring_get_str(qobject_to_qstring(qdict_entry_value(entry))));
> +
> +        item->next = %(obj)s;
> +        %(obj)s = item;
> +    }
> +}
> +''',
> +                        obj=c_var(argname))
> +        else:
> +            ret += mcgen('''
>   %(visitor)s(v,&%(c_name)s, "%(name)s", errp);
>   ''',
>                        c_name=c_var(argname), name=argname, argtype=argtype,
>                        visitor=type_visitor(argtype))
> -        if optional:
> +        if optional and not '**':
>               pop_indent()
>               ret += mcgen('''
>   }
> diff --git a/scripts/qapi.py b/scripts/qapi.py
> index e062336..87b9ee6 100644
> --- a/scripts/qapi.py
> +++ b/scripts/qapi.py
> @@ -163,6 +163,8 @@ def c_type(name):
>           return 'bool'
>       elif name == 'number':
>           return 'double'
> +    elif name == '**':
> +        return 'KeyValuesList *'
>       elif type(name) == list:
>           return '%s *' % c_list_type(name[0])
>       elif is_enum(name):