qemu-replies-tool: Add validation of known fields in 'query-qmp-schema'

If the schema itself is extended in qemu we need to have a notification
to add appropriate handling to ensure that we have full coverage of all
fields.

Add validation that only fields that libvirt currently knows about are
present in the schema.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>

scripts/qemu-replies-tool.py

@@ -16,6 +16,10 @@ class qrtException(Exception):
     pass
 
 
+class qmpSchemaException(Exception):
+    pass
+
+
 # Load the 'replies' file into a list of (command, reply) tuples of parsed JSON
 def qemu_replies_load(filename):
     conv = []
@@ -162,17 +166,155 @@ def modify_replies(conv):
         conv.insert(idx, (cmd, reply_unsupp))
 
 
+# Validates that 'entry' (an member of the QMP schema):
+# - checks that it's a Dict (imported from a JSON object)
+# - checks that all 'mandatory' fields are present and their types match
+# - checks the types of all 'optional' fields
+# - checks that no unknown fields are present
+def validate_qmp_schema_check_keys(entry, mandatory, optional):
+    keys = set(entry.keys())
+
+    for k, t in mandatory:
+        try:
+            keys.remove(k)
+        except KeyError:
+            raise qmpSchemaException("missing mandatory key '%s' in schema '%s'" % (k, entry))
+
+        if not isinstance(entry[k], t):
+            raise qmpSchemaException("key '%s' is not of the expected type '%s' in schema '%s'" % (k, t, entry))
+
+    for k, t in optional:
+        if k in keys:
+            keys.discard(k)
+
+            if not isinstance(entry[k], t):
+                raise qmpSchemaException("key '%s' is not of the expected type '%s' in schema '%s'" % (k, t, entry))
+
+    if len(keys) > 0:
+        raise qmpSchemaException("unhandled keys '%s' in schema '%s'" % (','.join(list(keys)), entry))
+
+
+# Validates the optional 'features' and that they consist only of strings
+def validate_qmp_schema_check_features_list(entry):
+    for f in entry.get('features', []):
+        if not isinstance(f, str):
+            raise qmpSchemaException("broken 'features' list in schema entry '%s'" % entry)
+
+
+# Validate that the passed schema has only members supported by this script and
+# by the libvirt internals. This is useful to stay up to date with any changes
+# to the schema.
+def validate_qmp_schema(schemalist):
+    for entry in schemalist:
+        if not isinstance(entry, dict):
+            raise qmpSchemaException("schema entry '%s' is not a JSON Object (dict)" % (entry))
+
+        if entry.get('meta-type', None) == 'command':
+            validate_qmp_schema_check_keys(entry,
+                                           mandatory=[('name', str),
+                                                      ('meta-type', str),
+                                                      ('arg-type', str),
+                                                      ('ret-type', str)],
+                                           optional=[('features', list),
+                                                     ('allow-oob', bool)])
+
+            validate_qmp_schema_check_features_list(entry)
+
+        elif entry.get('meta-type', None) == 'event':
+            validate_qmp_schema_check_keys(entry,
+                                           mandatory=[('name', str),
+                                                      ('meta-type', str),
+                                                      ('arg-type', str)],
+                                           optional=[('features', list)])
+
+            validate_qmp_schema_check_features_list(entry)
+
+        elif entry.get('meta-type', None) == 'object':
+            validate_qmp_schema_check_keys(entry,
+                                           mandatory=[('name', str),
+                                                      ('meta-type', str),
+                                                      ('members', list)],
+                                           optional=[('tag', str),
+                                                     ('variants', list),
+                                                     ('features', list)])
+
+            validate_qmp_schema_check_features_list(entry)
+
+            for m in entry.get('members', []):
+                validate_qmp_schema_check_keys(m,
+                                               mandatory=[('name', str),
+                                                          ('type', str)],
+                                               optional=[('default', type(None)),
+                                                         ('features', list)])
+                validate_qmp_schema_check_features_list(m)
+
+            for m in entry.get('variants', []):
+                validate_qmp_schema_check_keys(m,
+                                               mandatory=[('case', str),
+                                                          ('type', str)],
+                                               optional=[])
+
+        elif entry.get('meta-type', None) == 'array':
+            validate_qmp_schema_check_keys(entry,
+                                           mandatory=[('name', str),
+                                                      ('meta-type', str),
+                                                      ('element-type', str)],
+                                           optional=[])
+
+        elif entry.get('meta-type', None) == 'enum':
+            validate_qmp_schema_check_keys(entry,
+                                           mandatory=[('name', str),
+                                                      ('meta-type', str)],
+                                           optional=[('members', list),
+                                                     ('values', list)])
+
+            for m in entry.get('members', []):
+                validate_qmp_schema_check_keys(m,
+                                               mandatory=[('name', str)],
+                                               optional=[('features', list)])
+                validate_qmp_schema_check_features_list(m)
+
+        elif entry.get('meta-type', None) == 'alternate':
+            validate_qmp_schema_check_keys(entry,
+                                           mandatory=[('name', str),
+                                                      ('meta-type', str),
+                                                      ('members', list)],
+                                           optional=[])
+
+            for m in entry.get('members', []):
+                validate_qmp_schema_check_keys(m,
+                                               mandatory=[('type', str)],
+                                               optional=[])
+
+        elif entry.get('meta-type', None) == 'builtin':
+            validate_qmp_schema_check_keys(entry,
+                                           mandatory=[('name', str),
+                                                      ('meta-type', str),
+                                                      ('json-type', str)],
+                                           optional=[])
+
+        else:
+            raise qmpSchemaException("unknown or missing 'meta-type' in schema entry '%s'" % entry)
+
+
 def process_one(filename, args):
     try:
         conv = qemu_replies_load(filename)
 
         modify_replies(conv)
 
+        for (cmd, rep) in conv:
+            if cmd['execute'] == 'query-qmp-schema':
+                validate_qmp_schema(rep['return'])
+
         qemu_replies_compare_or_replace(filename, conv, args.regenerate)
 
     except qrtException as e:
         print("'%s' ... FAIL\n%s" % (filename, e))
         return False
+    except qmpSchemaException as qe:
+        print("'%s' ... FAIL\nqmp schema error: %s" % (filename, qe))
+        return False
 
     print("'%s' ... OK" % filename)
     return True
@@ -191,6 +333,7 @@ The default mode is validation which checks the following:
     - each command has a reply and both are valid JSON
     - numbering of the 'id' field is as expected
     - the input file has the expected JSON formatting
+    - the QMP schema from qemu is fully covered by libvirt's code
 
 The tool can be also used to programmaticaly modify the '.replies' file by
 editing the 'modify_replies' method directly in the source, or for