qapi: Check for member name conflicts with a base class

Our type inheritance for both 'struct' and for flat 'union' merges
key/value pairs from the base class with those from the type in
question.  Although the C code currently boxes things so that there
is a distinction between which member is referred to, the QMP wire
format does not allow passing a key more than once in a single
object.  Besides, if we ever change the generated C code to not be
quite so boxy, we'd want to avoid duplicate member names there,
too.

Fix a testsuite entry added in an earlier patch, as well as adding
a couple more tests to ensure we have appropriate coverage.  Ensure
that collisions are detected, regardless of whether there is a
difference in opinion on whether the member name is optional.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

scripts/qapi.py

@@ -414,6 +414,20 @@ def check_type(expr_info, source, value, allow_array = False,
                    allow_metas=['built-in', 'union', 'alternate', 'struct',
                                 'enum'])
 
+def check_member_clash(expr_info, base_name, data, source = ""):
+    base = find_struct(base_name)
+    assert base
+    base_members = base['data']
+    for key in data.keys():
+        if key.startswith('*'):
+            key = key[1:]
+        if key in base_members or "*" + key in base_members:
+            raise QAPIExprError(expr_info,
+                                "Member name '%s'%s clashes with base '%s'"
+                                % (key, source, base_name))
+    if base.get('base'):
+        check_member_clash(expr_info, base['base'], data, source)
+
 def check_command(expr, expr_info):
     name = expr['command']
     allow_star = expr.has_key('gen')
@@ -503,9 +517,14 @@ def check_union(expr, expr_info):
         check_name(expr_info, "Member of union '%s'" % name, key)
 
         # Each value must name a known type; furthermore, in flat unions,
-        # branches must be a struct
+        # branches must be a struct with no overlapping member names
         check_type(expr_info, "Member '%s' of union '%s'" % (key, name),
                    value, allow_array=True, allow_metas=allow_metas)
+        if base:
+            branch_struct = find_struct(value)
+            assert branch_struct
+            check_member_clash(expr_info, base, branch_struct['data'],
+                               " of branch '%s'" % key)
 
         # If the discriminator names an enum type, then all members
         # of 'data' must also be members of the enum type.
@@ -582,6 +601,8 @@ def check_struct(expr, expr_info):
                allow_dict=True, allow_optional=True)
     check_type(expr_info, "'base' for struct '%s'" % name, expr.get('base'),
                allow_metas=['struct'])
+    if expr.get('base'):
+        check_member_clash(expr_info, expr['base'], expr['data'])
 
 def check_exprs(schema):
     for expr_elem in schema.exprs:

tests/Makefile

@@ -243,7 +243,8 @@ check-qapi-schema-y := $(addprefix tests/qapi-schema/, \
 	include-simple.json include-relpath.json include-format-err.json \
 	include-non-file.json include-no-file.json include-before-err.json \
 	include-nested-err.json include-self-cycle.json include-cycle.json \
-	include-repetition.json event-nest-struct.json event-case.json)
+	include-repetition.json event-nest-struct.json event-case.json \
+	struct-base-clash.json struct-base-clash-deep.json )
 
 GENERATED_HEADERS += tests/test-qapi-types.h tests/test-qapi-visit.h \
 		     tests/test-qmp-commands.h tests/test-qapi-event.h

tests/qapi-schema/flat-union-branch-clash.err

+tests/qapi-schema/flat-union-branch-clash.json:10: Member name 'name' of branch 'value1' clashes with base 'Base'

tests/qapi-schema/flat-union-branch-clash.exit

-0
+1

tests/qapi-schema/flat-union-branch-clash.json

-# FIXME: we should check for no duplicate keys between branches and base
+# we check for no duplicate keys between branches and base
 { 'enum': 'TestEnum',
   'data': [ 'value1', 'value2' ] }
 { 'struct': 'Base',
-  'data': { 'enum1': 'TestEnum', 'name': 'str' } }
+  'data': { 'enum1': 'TestEnum', '*name': 'str' } }
 { 'struct': 'Branch1',
   'data': { 'name': 'str' } }
 { 'struct': 'Branch2',

tests/qapi-schema/flat-union-branch-clash.out

-[OrderedDict([('enum', 'TestEnum'), ('data', ['value1', 'value2'])]),
- OrderedDict([('struct', 'Base'), ('data', OrderedDict([('enum1', 'TestEnum'), ('name', 'str')]))]),
- OrderedDict([('struct', 'Branch1'), ('data', OrderedDict([('name', 'str')]))]),
- OrderedDict([('struct', 'Branch2'), ('data', OrderedDict([('value', 'int')]))]),
- OrderedDict([('union', 'TestUnion'), ('base', 'Base'), ('discriminator', 'enum1'), ('data', OrderedDict([('value1', 'Branch1'), ('value2', 'Branch2')]))])]
-[{'enum_name': 'TestEnum', 'enum_values': ['value1', 'value2']}]
-[OrderedDict([('struct', 'Base'), ('data', OrderedDict([('enum1', 'TestEnum'), ('name', 'str')]))]),
- OrderedDict([('struct', 'Branch1'), ('data', OrderedDict([('name', 'str')]))]),
- OrderedDict([('struct', 'Branch2'), ('data', OrderedDict([('value', 'int')]))])]

tests/qapi-schema/struct-base-clash-deep.err

+tests/qapi-schema/struct-base-clash-deep.json:7: Member name 'name' clashes with base 'Base'

tests/qapi-schema/struct-base-clash-deep.exit

+1

tests/qapi-schema/struct-base-clash-deep.json

+# we check for no duplicate keys with indirect base
+{ 'struct': 'Base',
+  'data': { 'name': 'str' } }
+{ 'struct': 'Mid',
+  'base': 'Base',
+  'data': { 'value': 'int' } }
+{ 'struct': 'Sub',
+  'base': 'Mid',
+  'data': { '*name': 'str' } }

tests/qapi-schema/struct-base-clash.err

+tests/qapi-schema/struct-base-clash.json:4: Member name 'name' clashes with base 'Base'

tests/qapi-schema/struct-base-clash.exit

+1

tests/qapi-schema/struct-base-clash.json

+# we check for no duplicate keys with base
+{ 'struct': 'Base',
+  'data': { 'name': 'str' } }
+{ 'struct': 'Sub',
+  'base': 'Base',
+  'data': { 'name': 'str' } }