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https://github.com/yuzu-emu/unicorn.git
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ef6b7b50f6
Right now, qmp-output-visitor happens to produce a QNull result if nothing is actually visited between the creation of the visitor and the request for the resulting QObject. A stronger protocol would require that a QMP output visit MUST visit something. But to still be able to produce a JSON 'null' output, we need a new visitor function that states our intentions. Yes, we could say that such a visit must go through visit_type_any(), but that feels clunky. So this patch introduces the new visit_type_null() interface and its no-op interface in the dealloc visitor, and stubs in the qmp visitors (the next patch will finish the implementation). For the visitors that will not implement the callback, document the situation. The code in qapi-visit-core unconditionally dereferences the callback pointer, so that a segfault will inform a developer if they need to implement the callback for their choice of visitor. Note that JSON has a primitive null type, with the single value null; likewise with the QNull type for QObject; but for QAPI, we just have the 'null' value without a null type. We may eventually want to add more support in QAPI for null (most likely, we'd use it via an alternate type that permits 'null' or an object); but we'll create that usage when we need it. Backports commit 3bc97fd5924561d92f32758c67eaffd2e4e25038 from qemu
213 lines
5.2 KiB
C
213 lines
5.2 KiB
C
/*
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* Dealloc Visitor
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*
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* Copyright IBM, Corp. 2011
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*
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* Authors:
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* Michael Roth <mdroth@linux.vnet.ibm.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "qapi/dealloc-visitor.h"
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#include "qemu/queue.h"
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#include "qemu-common.h"
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#include "qapi/qmp/types.h"
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#include "qapi/visitor-impl.h"
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typedef struct StackEntry
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{
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void *value;
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bool is_list_head;
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QTAILQ_ENTRY(StackEntry) node;
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} StackEntry;
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struct QapiDeallocVisitor
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{
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Visitor visitor;
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QTAILQ_HEAD(, StackEntry) stack;
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bool is_list_head;
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};
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static QapiDeallocVisitor *to_qov(Visitor *v)
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{
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return container_of(v, QapiDeallocVisitor, visitor);
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}
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static void qapi_dealloc_push(QapiDeallocVisitor *qov, void *value)
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{
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StackEntry *e = g_malloc0(sizeof(*e));
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e->value = value;
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/* see if we're just pushing a list head tracker */
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if (value == NULL) {
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e->is_list_head = true;
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}
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QTAILQ_INSERT_HEAD(&qov->stack, e, node);
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}
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static void *qapi_dealloc_pop(QapiDeallocVisitor *qov)
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{
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StackEntry *e = QTAILQ_FIRST(&qov->stack);
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QObject *value;
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QTAILQ_REMOVE(&qov->stack, e, node);
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value = e->value;
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g_free(e);
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return value;
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}
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static void qapi_dealloc_start_struct(Visitor *v, const char *name, void **obj,
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size_t unused, Error **errp)
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{
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QapiDeallocVisitor *qov = to_qov(v);
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qapi_dealloc_push(qov, obj);
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}
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static void qapi_dealloc_end_struct(Visitor *v, Error **errp)
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{
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QapiDeallocVisitor *qov = to_qov(v);
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void **obj = qapi_dealloc_pop(qov);
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if (obj) {
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g_free(*obj);
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}
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}
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static void qapi_dealloc_start_alternate(Visitor *v, const char *name,
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GenericAlternate **obj, size_t size,
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bool promote_int, Error **errp)
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{
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QapiDeallocVisitor *qov = to_qov(v);
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qapi_dealloc_push(qov, obj);
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}
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static void qapi_dealloc_end_alternate(Visitor *v)
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{
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QapiDeallocVisitor *qov = to_qov(v);
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void **obj = qapi_dealloc_pop(qov);
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if (obj) {
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g_free(*obj);
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}
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}
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static void qapi_dealloc_start_list(Visitor *v, const char *name, Error **errp)
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{
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QapiDeallocVisitor *qov = to_qov(v);
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qapi_dealloc_push(qov, NULL);
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}
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static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList **listp,
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size_t size)
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{
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GenericList *list = *listp;
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QapiDeallocVisitor *qov = to_qov(v);
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StackEntry *e = QTAILQ_FIRST(&qov->stack);
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if (e && e->is_list_head) {
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e->is_list_head = false;
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return list;
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}
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if (list) {
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list = list->next;
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g_free(*listp);
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return list;
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}
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return NULL;
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}
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static void qapi_dealloc_end_list(Visitor *v)
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{
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QapiDeallocVisitor *qov = to_qov(v);
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void *obj = qapi_dealloc_pop(qov);
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assert(obj == NULL); /* should've been list head tracker with no payload */
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}
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static void qapi_dealloc_type_str(Visitor *v, const char *name, char **obj,
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Error **errp)
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{
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if (obj) {
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g_free(*obj);
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}
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}
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static void qapi_dealloc_type_int64(Visitor *v, const char *name, int64_t *obj,
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Error **errp)
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{
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}
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static void qapi_dealloc_type_uint64(Visitor *v, const char *name,
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uint64_t *obj, Error **errp)
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{
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}
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static void qapi_dealloc_type_bool(Visitor *v, const char *name, bool *obj,
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Error **errp)
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{
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}
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static void qapi_dealloc_type_number(Visitor *v, const char *name, double *obj,
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Error **errp)
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{
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}
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static void qapi_dealloc_type_anything(Visitor *v, const char *name,
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QObject **obj, Error **errp)
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{
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if (obj) {
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qobject_decref(*obj);
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}
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}
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static void qapi_dealloc_type_size(Visitor *v, const char *name, uint64_t *obj,
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Error **errp)
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{
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}
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static void qapi_dealloc_type_null(Visitor *v, const char *name, Error **errp)
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{
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}
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Visitor *qapi_dealloc_get_visitor(QapiDeallocVisitor *v)
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{
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return &v->visitor;
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}
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void qapi_dealloc_visitor_cleanup(QapiDeallocVisitor *v)
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{
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g_free(v);
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}
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QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
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{
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QapiDeallocVisitor *v;
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v = g_malloc0(sizeof(*v));
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v->visitor.type = VISITOR_DEALLOC;
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v->visitor.start_struct = qapi_dealloc_start_struct;
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v->visitor.end_struct = qapi_dealloc_end_struct;
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v->visitor.start_alternate = qapi_dealloc_start_alternate;
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v->visitor.end_alternate = qapi_dealloc_end_alternate;
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v->visitor.start_list = qapi_dealloc_start_list;
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v->visitor.next_list = qapi_dealloc_next_list;
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v->visitor.end_list = qapi_dealloc_end_list;
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v->visitor.type_int64 = qapi_dealloc_type_int64;
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v->visitor.type_uint64 = qapi_dealloc_type_uint64;
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v->visitor.type_bool = qapi_dealloc_type_bool;
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v->visitor.type_str = qapi_dealloc_type_str;
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v->visitor.type_number = qapi_dealloc_type_number;
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v->visitor.type_any = qapi_dealloc_type_anything;
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v->visitor.type_null = qapi_dealloc_type_null;
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v->visitor.type_size = qapi_dealloc_type_size;
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QTAILQ_INIT(&v->stack);
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return v;
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}
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