From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59426) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VN0qW-000892-3p for qemu-devel@nongnu.org; Fri, 20 Sep 2013 09:34:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VN0qM-0004EJ-UE for qemu-devel@nongnu.org; Fri, 20 Sep 2013 09:34:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24549) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VN0qM-0004E8-Lv for qemu-devel@nongnu.org; Fri, 20 Sep 2013 09:33:58 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r8KDXwuw029411 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 20 Sep 2013 09:33:58 -0400 Message-ID: <523C4EC3.5010909@redhat.com> Date: Fri, 20 Sep 2013 15:33:55 +0200 From: Max Reitz MIME-Version: 1.0 References: <1379678070-14346-1-git-send-email-kwolf@redhat.com> <1379678070-14346-3-git-send-email-kwolf@redhat.com> In-Reply-To: <1379678070-14346-3-git-send-email-kwolf@redhat.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 02/17] qapi-types/visit.py: Inheritance for structs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, stefanha@redhat.com, armbru@redhat.com On 2013-09-20 13:54, Kevin Wolf wrote: > This introduces a new 'base' key for struct definitions that refers to > another struct type. On the JSON level, the fields of the base type are > included directly into the same namespace as the fields of the defined > type, like with unions. On the C level, a pointer to a struct of the > base type is included. > > Signed-off-by: Kevin Wolf > --- > docs/qapi-code-gen.txt | 17 +++++++++++++++++ > scripts/qapi-types.py | 4 ++++ > scripts/qapi-visit.py | 18 ++++++++++++++++-- > 3 files changed, 37 insertions(+), 2 deletions(-) > > diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt > index 0ce045c..2b872f1 100644 > --- a/docs/qapi-code-gen.txt > +++ b/docs/qapi-code-gen.txt > @@ -53,6 +53,23 @@ The use of '*' as a prefix to the name means the member is optional. Optional > members should always be added to the end of the dictionary to preserve > backwards compatibility. > > + > +A complex type definition can specify another complex type as its base. > +In this case, the fields of the base type are included as top-level fields > +of the new complex type's dictionary in the QMP wire format. An example > +definition is: > + > + { 'type': 'BlockdevOptionsGenericFormat', 'data': { 'file': 'str' } } > + { 'type': 'BlockdevOptionsGenericCOWFormat', > + 'base': 'BlockdevOptionsGenericFormat', > + 'data': { '*backing': 'str' } } > + > +An example BlockdevOptionsGenericCOWFormat object on the wire could use > +both fields like this: > + > + { "file": "/some/place/my-image" > + "backing": "/some/place/my-backing-file" } } > + > === Enumeration types === > > An enumeration type is a dictionary containing a single key whose value is a > diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py > index 566fe5e..4a1652b 100644 > --- a/scripts/qapi-types.py > +++ b/scripts/qapi-types.py > @@ -86,6 +86,7 @@ def generate_struct(expr): > structname = expr.get('type', "") > fieldname = expr.get('field', "") > members = expr['data'] > + base = expr.get('base') > > ret = mcgen(''' > struct %(name)s > @@ -93,6 +94,9 @@ struct %(name)s > ''', > name=structname) > > + if base: > + ret += generate_struct_fields({'base': base}) > + > ret += generate_struct_fields(members) > > if len(fieldname): > diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py > index 1e44004..90cedd7 100644 > --- a/scripts/qapi-visit.py > +++ b/scripts/qapi-visit.py > @@ -17,7 +17,7 @@ import os > import getopt > import errno > > -def generate_visit_struct_fields(name, field_prefix, fn_prefix, members): > +def generate_visit_struct_fields(name, field_prefix, fn_prefix, members, base = None): > substructs = [] > ret = '' > full_name = name if not fn_prefix else "%s_%s" % (name, fn_prefix) > @@ -42,6 +42,19 @@ static void visit_type_%(full_name)s_fields(Visitor *m, %(name)s ** obj, Error * > name=name, full_name=full_name) > push_indent() > > + if base: > + ret += mcgen(''' > +visit_start_implicit_struct(m, (void**) &(*obj)->%(c_name)s, sizeof(%(type)s), &err); Why do you just dereference obj here (implying it will never be NULL)... > +if (!err) { > + visit_type_%(type)s_fields(m, obj ? &(*obj)->%(c_prefix)s%(c_name)s : NULL, &err); ...but then you're checking whether it is NULL before dereferencing? Max > + error_propagate(errp, err); > + err = NULL; > + visit_end_implicit_struct(m, &err); > +} > +''', > + c_prefix=c_var(field_prefix), > + type=type_name(base), c_name=c_var('base')) > + > for argname, argentry, optional, structured in parse_args(members): > if optional: > ret += mcgen(''' > @@ -124,8 +137,9 @@ def generate_visit_struct(expr): > > name = expr['type'] > members = expr['data'] > + base = expr.get('base') > > - ret = generate_visit_struct_fields(name, "", "", members) > + ret = generate_visit_struct_fields(name, "", "", members, base) > > ret += mcgen(''' >