Commit 82ca8e46 authored by Eric Blake's avatar Eric Blake Committed by Markus Armbruster
Browse files

qapi: Share gen_visit_fields() 



Consolidate the code between visit, command marshalling, and
event generation that iterates over the members of a struct.
It reduces code duplication in the generator, so that a future
patch can reduce the size of generated code while touching only
one instead of three locations.

There are no changes to the generated marshal code.

The visitor code becomes slightly more verbose, but remains
semantically equivalent, and is actually easier to read as
it follows a more common idiom:

|     visit_optional(v, &(*obj)->has_device, "device", &err);
|-    if (!err && (*obj)->has_device) {
|-        visit_type_str(v, &(*obj)->device, "device", &err);
|-    }
|     if (err) {
|         goto out;
|     }
|+    if ((*obj)->has_device) {
|+        visit_type_str(v, &(*obj)->device, "device", &err);
|+        if (err) {
|+            goto out;
|+        }
|+    }

The event code becomes slightly more verbose, but this is
arguably a bug fix: although the visitors are not well
documented, use of an optional member should not be attempted
unless guarded by a prior call to visit_optional().  Works only
because the output qmp visitor has a no-op visit_optional():

|+    visit_optional(v, &has_offset, "offset", &err);
|+    if (err) {
|+        goto out;
|+    }
|     if (has_offset) {
|         visit_type_int(v, &offset, "offset", &err);

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Message-Id: <1443565276-4535-17-git-send-email-eblake@redhat.com>
Signed-off-by: default avatarMarkus Armbruster <armbru@redhat.com>
parent 1f353344

scripts/qapi-commands.py

+1 −26
Original line number Diff line number Diff line
@@ -101,7 +101,6 @@ def gen_marshal_input_visit(arg_type, dealloc=False): 
        return ret



    if dealloc:

        errparg = 'NULL'

        errarg = None

        ret += mcgen('''

    qmp_input_visitor_cleanup(qiv);
@@ -109,36 +108,12 @@ def gen_marshal_input_visit(arg_type, dealloc=False): 
    v = qapi_dealloc_get_visitor(qdv);

''')

    else:

        errparg = '&err'

        errarg = 'err'

        ret += mcgen('''

    v = qmp_input_get_visitor(qiv);

''')



    for memb in arg_type.members:

        if memb.optional:

            ret += mcgen('''

    visit_optional(v, &has_%(c_name)s, "%(name)s", %(errp)s);

''',

                         c_name=c_name(memb.name), name=memb.name,

                         errp=errparg)

            ret += gen_err_check(err=errarg)

            ret += mcgen('''

    if (has_%(c_name)s) {

''',

                         c_name=c_name(memb.name))

            push_indent()

        ret += mcgen('''

    visit_type_%(c_type)s(v, &%(c_name)s, "%(name)s", %(errp)s);

''',

                     c_name=c_name(memb.name), name=memb.name,

                     c_type=memb.type.c_name(), errp=errparg)

        ret += gen_err_check(err=errarg)

        if memb.optional:

            pop_indent()

            ret += mcgen('''

    }

''')

    ret += gen_visit_fields(arg_type.members, errarg=errarg)



    if dealloc:

        ret += mcgen('''

scripts/qapi-event.py

+1 −30
Original line number Diff line number Diff line
@@ -71,36 +71,7 @@ def gen_event_send(name, arg_type): 
''',

                     name=name)

        ret += gen_err_check()



        for memb in arg_type.members:

            if memb.optional:

                ret += mcgen('''

    if (has_%(c_name)s) {

''',

                             c_name=c_name(memb.name))

                push_indent()



            # Ugly: need to cast away the const

            if memb.type.name == "str":

                cast = '(char **)'

            else:

                cast = ''



            ret += mcgen('''

    visit_type_%(c_type)s(v, %(cast)s&%(c_name)s, "%(name)s", &err);

''',

                         cast=cast,

                         c_name=c_name(memb.name),

                         c_type=memb.type.c_name(),

                         name=memb.name)

            ret += gen_err_check()



            if memb.optional:

                pop_indent()

                ret += mcgen('''

    }

''')



        ret += gen_visit_fields(arg_type.members, need_cast=True)

        ret += mcgen('''

    visit_end_struct(v, &err);

    if (err) {

scripts/qapi-visit.py

+1 −21
Original line number Diff line number Diff line
@@ -85,27 +85,7 @@ static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s **obj, Error **e 
                     c_type=base.c_name(), c_name=c_name('base'))

        ret += gen_err_check()



    for memb in members:

        if memb.optional:

            ret += mcgen('''

    visit_optional(v, &(*obj)->has_%(c_name)s, "%(name)s", &err);

    if (!err && (*obj)->has_%(c_name)s) {

''',

                         c_name=c_name(memb.name), name=memb.name)

            push_indent()



        ret += mcgen('''

    visit_type_%(c_type)s(v, &(*obj)->%(c_name)s, "%(name)s", &err);

''',

                     c_type=memb.type.c_name(), c_name=c_name(memb.name),

                     name=memb.name)



        if memb.optional:

            pop_indent()

            ret += mcgen('''

    }

''')

        ret += gen_err_check()

    ret += gen_visit_fields(members, prefix='(*obj)->')



    if re.search('^ *goto out;', ret, re.MULTILINE):

        ret += mcgen('''

scripts/qapi.py

+43 −0
Original line number Diff line number Diff line
@@ -1548,6 +1548,49 @@ def gen_err_check(err='err', label='out'): 
                 err=err, label=label)





def gen_visit_fields(members, prefix='', need_cast=False, errarg='err'):

    ret = ''

    if errarg:

        errparg = '&' + errarg

    else:

        errparg = 'NULL'



    for memb in members:

        if memb.optional:

            ret += mcgen('''

    visit_optional(v, &%(prefix)shas_%(c_name)s, "%(name)s", %(errp)s);

''',

                         prefix=prefix, c_name=c_name(memb.name),

                         name=memb.name, errp=errparg)

            ret += gen_err_check(err=errarg)

            ret += mcgen('''

    if (%(prefix)shas_%(c_name)s) {

''',

                         prefix=prefix, c_name=c_name(memb.name))

            push_indent()



        # Ugly: sometimes we need to cast away const

        if need_cast and memb.type.name == 'str':

            cast = '(char **)'

        else:

            cast = ''



        ret += mcgen('''

    visit_type_%(c_type)s(v, %(cast)s&%(prefix)s%(c_name)s, "%(name)s", %(errp)s);

''',

                     c_type=memb.type.c_name(), prefix=prefix, cast=cast,

                     c_name=c_name(memb.name), name=memb.name,

                     errp=errparg)

        ret += gen_err_check(err=errarg)



        if memb.optional:

            pop_indent()

            ret += mcgen('''

    }

''')

    return ret





#

# Common command line parsing

#