[Qemu-devel] [PATCH v4 4/5] qmp: full introspection support for QMP

[Amos Kong <akong@redhat.com>]

This patch introduces a new monitor command to query QMP schema
information, the return data is a range of schema structs, which
contains the useful metadata to help management to check supported
features, QMP commands detail, etc.

We use qapi-introspect.py to parse all json definition in
qapi-schema.json, and generate a range of dictionaries with metadata.
The query command will visit the dictionaries and fill the data
to allocated struct tree. Then QMP infrastructure will convert
the tree to json string and return to QMP client.

TODO:
Wenchao Xia is working to convert QMP events to qapi-schema.json,
then event can also be queried by this interface.

I will introduce another command 'query-qga-schema' to query QGA
schema information, it's easy to add this support based on this
patch.

Signed-off-by: Amos Kong <akong@redhat.com>
---
 qapi-schema.json |  11 +++
 qmp-commands.hx  |  42 +++++++++++
 qmp.c            | 215 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 268 insertions(+)

diff --git a/qapi-schema.json b/qapi-schema.json
index c63f0ca..6033383 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4411,3 +4411,14 @@
     'reference-type': 'String',
     'type': 'DataObjectType',
     'unionobj': 'DataObjectUnion' } }
+
+##
+# @query-qmp-schema
+#
+# Query QMP schema information
+#
+# @returns: list of @DataObject
+#
+# Since: 1.8
+##
+{ 'command': 'query-qmp-schema', 'returns': ['DataObject'] }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 02cc815..b83762d 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -3291,6 +3291,48 @@ Example:
    }
 
 EQMP
+    {
+        .name       = "query-qmp-schema",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_query_qmp_schema,
+    },
+
+
+SQMP
+query-qmp-schema
+----------------
+
+query qmp schema information
+
+Return a json-object with the following information:
+
+- "name": qmp schema name (json-string)
+- "type": qmp schema type, it can be 'comand', 'type', 'enum', 'union'
+- "returns": return data of qmp command (json-object, optional)
+
+Example:
+
+-> { "execute": "query-qmp-schema" }
+-> { "return": [
+     {
+         "name": "query-name",
+         "type": "command",
+         "returns": {
+             "name": "NameInfo",
+             "type": "type",
+             "data": [
+                 {
+                     "name": "name",
+                     "optional": true,
+                     "recursive": false,
+                     "type": "str"
+                 }
+             ]
+         }
+     }
+  }
+
+EQMP
 
     {
         .name       = "blockdev-add",
diff --git a/qmp.c b/qmp.c
index 0f46171..a64ae6d 100644
--- a/qmp.c
+++ b/qmp.c
@@ -27,6 +27,8 @@
 #include "qapi/qmp/qobject.h"
 #include "qapi/qmp-input-visitor.h"
 #include "hw/boards.h"
+#include "qapi/qmp/qjson.h"
+#include "qapi-introspect.h"
 
 NameInfo *qmp_query_name(Error **errp)
 {
@@ -488,6 +490,219 @@ CpuDefinitionInfoList *qmp_query_cpu_definitions(Error **errp)
     return arch_query_cpu_definitions(errp);
 }
 
+static strList *qobject_to_strlist(QObject *data)
+{
+    strList *list = NULL;
+    strList **plist = &list;
+    QList *qlist;
+    const QListEntry *lent;
+
+    qlist = qobject_to_qlist(data);
+    for (lent = qlist_first(qlist); lent; lent = qlist_next(lent)) {
+        strList *entry = g_malloc0(sizeof(strList));
+        entry->value = g_strdup(qobject_get_str(lent->value));
+        *plist = entry;
+        plist = &entry->next;
+    }
+
+    return list;
+}
+
+static DataObject *qobject_to_dataobj(QObject *data);
+
+static DataObjectMember *qobject_to_dataobjmem(QObject *data)
+{
+
+    DataObjectMember *member = g_malloc0(sizeof(DataObjectMember));
+
+    member->type = g_malloc0(sizeof(DataObjectMemberType));
+    if (data->type->code == QTYPE_QDICT) {
+        member->type->kind = DATA_OBJECT_MEMBER_TYPE_KIND_EXTEND;
+        member->type->extend = qobject_to_dataobj(data);
+    } else {
+        member->type->kind = DATA_OBJECT_MEMBER_TYPE_KIND_REFERENCE;
+        member->type->reference = g_strdup(qobject_get_str(data));
+    }
+
+    return member;
+}
+
+static DataObjectMemberList *qobject_to_dict_memlist(QObject *data)
+{
+    DataObjectMemberList *list = NULL;
+    DataObjectMemberList **plist = &list;
+    QDict *qdict = qobject_to_qdict(data);
+    const QDictEntry *dent;
+
+    for (dent = qdict_first(qdict); dent; dent = qdict_next(qdict, dent)) {
+        DataObjectMemberList *entry = g_malloc0(sizeof(DataObjectMemberList));
+        entry->value = qobject_to_dataobjmem(dent->value);
+
+        entry->value->has_optional = true;
+        entry->value->has_name = true;
+        if (dent->key[0] == '*') {
+            entry->value->optional = true;
+            entry->value->name = g_strdup(dent->key + 1);
+        } else {
+            entry->value->name = g_strdup(dent->key);
+        }
+        *plist = entry;
+        plist = &entry->next;
+    }
+
+    return list;
+}
+
+static DataObjectMemberList *qobject_to_list_memlist(QObject *data)
+{
+    const QListEntry *lent;
+    DataObjectMemberList *list = NULL;
+    DataObjectMemberList **plist = &list;
+    QList *qlist = qobject_to_qlist(data);
+
+    for (lent = qlist_first(qlist); lent; lent = qlist_next(lent)) {
+        DataObjectMemberList *entry = g_malloc0(sizeof(DataObjectMemberList));
+        entry->value = qobject_to_dataobjmem(lent->value);
+        entry->value->has_optional = true;
+        entry->value->has_name = true;
+        *plist = entry;
+        plist = &entry->next;
+    }
+
+    return list;
+}
+
+static DataObjectMemberList *qobject_to_memlist(QObject *data)
+{
+    DataObjectMemberList *list = NULL;
+    QDict *qdict = qobject_to_qdict(data);
+    QObject *subdata = qdict_get(qdict, "_obj_data");
+
+    list = NULL;
+    if (subdata->type->code == QTYPE_QDICT) {
+        list = qobject_to_dict_memlist(subdata);
+    } else if (subdata->type->code == QTYPE_QLIST) {
+        list = qobject_to_list_memlist(subdata);
+    }
+
+    return list;
+}
+
+static DataObject *qobject_to_dataobj(QObject *data)
+{
+    QObject *subdata;
+    QDict *qdict;
+    const char *obj_type, *obj_recursive;
+    DataObject *obj = g_malloc0(sizeof(DataObject));
+
+    if (data->type->code == QTYPE_QSTRING) {
+        obj->kind = DATA_OBJECT_KIND_REFERENCE_TYPE;
+        obj->reference_type = g_malloc0(sizeof(String));
+        obj->reference_type->str = g_strdup(qobject_get_str(data));
+        return obj;
+    }
+
+    qdict = qobject_to_qdict(data);
+    assert(qdict != NULL);
+
+    obj_type = qobject_get_str(qdict_get(qdict, "_obj_type"));
+    obj_recursive = qobject_get_str(qdict_get(qdict, "_obj_recursive"));
+    if (!strcmp(obj_recursive, "True")) {
+        obj->has_recursive = true;
+        obj->recursive = true;
+    }
+
+    obj->has_name = true;
+    obj->name = g_strdup(qobject_get_str(qdict_get(qdict, "_obj_name")));
+
+    subdata = qdict_get(qdict, "_obj_data");
+    qdict = qobject_to_qdict(subdata);
+
+    if (!strcmp(obj_type, "command")) {
+        obj->kind = DATA_OBJECT_KIND_COMMAND;
+        obj->command = g_malloc0(sizeof(DataObjectCommand));
+        subdata = qdict_get(qobject_to_qdict(subdata), "data");
+
+        if (subdata && subdata->type->code == QTYPE_QDICT) {
+            obj->command->has_data = true;
+            obj->command->data = qobject_to_memlist(subdata);
+        } else if (subdata && subdata->type->code == QTYPE_QLIST) {
+            abort();
+        }
+
+        subdata = qdict_get(qdict, "returns");
+        if (subdata) {
+            obj->command->has_returns = true;
+            obj->command->returns = qobject_to_dataobj(subdata);
+        }
+
+        subdata = qdict_get(qdict, "gen");
+        if (subdata && subdata->type->code == QTYPE_QSTRING) {
+            obj->command->has_gen = true;
+            if (!strcmp(qobject_get_str(subdata), "no")) {
+                obj->command->gen = false;
+            } else {
+                obj->command->gen = true;
+            }
+        }
+    } else if (!strcmp(obj_type, "union")) {
+        obj->kind = DATA_OBJECT_KIND_UNIONOBJ;
+        obj->unionobj = g_malloc0(sizeof(DataObjectUnion));
+        subdata = qdict_get(qdict, "data");
+        obj->unionobj->data = qobject_to_memlist(subdata);
+
+        subdata = qdict_get(qdict, "base");
+        if (subdata) {
+            obj->unionobj->has_base = true;
+            obj->unionobj->base = qobject_to_dataobj(subdata);
+        }
+
+        subdata = qdict_get(qdict, "discriminator");
+        if (subdata) {
+            obj->unionobj->has_discriminator = true;
+            obj->unionobj->discriminator = qobject_to_dataobj(subdata);
+        }
+    } else if (!strcmp(obj_type, "type")) {
+        obj->kind = DATA_OBJECT_KIND_TYPE;
+        obj->type = g_malloc0(sizeof(DataObjectType));
+        subdata = qdict_get(qdict, "data");
+        if (subdata) {
+            obj->type->data = qobject_to_memlist(subdata);
+        }
+     } else if (!strcmp(obj_type, "enum")) {
+        obj->kind = DATA_OBJECT_KIND_ENUMERATION;
+        obj->enumeration = g_malloc0(sizeof(DataObjectEnumeration));
+        subdata = qdict_get(qdict, "data");
+        obj->enumeration->data = qobject_to_strlist(subdata);
+    } else {
+        obj->has_name = false;
+        obj->kind = DATA_OBJECT_KIND_ANONYMOUS_STRUCT;
+        obj->anonymous_struct = g_malloc0(sizeof(DataObjectAnonymousStruct));
+        obj->anonymous_struct->data = qobject_to_memlist(data);
+    }
+
+    return obj;
+}
+
+DataObjectList *qmp_query_qmp_schema(Error **errp)
+{
+    DataObjectList *list = NULL;
+    DataObjectList **plist = &list;
+    QObject *data;
+    int i;
+
+    for (i = 0; qmp_schema_table[i]; i++) {
+        data = qobject_from_json(qmp_schema_table[i]);
+        assert(data != NULL);
+        DataObjectList *entry = g_malloc0(sizeof(DataObjectList));
+        entry->value = qobject_to_dataobj(data);
+        *plist = entry;
+        plist = &entry->next;
+    }
+
+    return list;
+}
+
 void qmp_add_client(const char *protocol, const char *fdname,
                     bool has_skipauth, bool skipauth, bool has_tls, bool tls,
                     Error **errp)
-- 
1.8.4.2