qemu/qapi/qmp-output-visitor.c

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/*
* Core Definitions for QAPI/QMP Command Registry
*
* Copyright (C) 2012-2016 Red Hat, Inc.
* Copyright IBM, Corp. 2011
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "qapi/qmp-output-visitor.h"
#include "qapi/visitor-impl.h"
#include "qemu/queue.h"
#include "qemu-common.h"
#include "qapi/qmp/types.h"
typedef struct QStackEntry
{
QObject *value;
bool is_list_head;
QTAILQ_ENTRY(QStackEntry) node;
} QStackEntry;
typedef QTAILQ_HEAD(QStack, QStackEntry) QStack;
struct QmpOutputVisitor
{
Visitor visitor;
QStack stack; /* Stack of containers that haven't yet been finished */
QObject *root; /* Root of the output visit */
};
#define qmp_output_add(qov, name, value) \
qmp_output_add_obj(qov, name, QOBJECT(value))
#define qmp_output_push(qov, value) qmp_output_push_obj(qov, QOBJECT(value))
static QmpOutputVisitor *to_qov(Visitor *v)
{
return container_of(v, QmpOutputVisitor, visitor);
}
/* Push @value onto the stack of current QObjects being built */
static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
{
QStackEntry *e = g_malloc0(sizeof(*e));
assert(qov->root);
assert(value);
e->value = value;
if (qobject_type(e->value) == QTYPE_QLIST) {
e->is_list_head = true;
}
QTAILQ_INSERT_HEAD(&qov->stack, e, node);
}
/* Pop a value off the stack of QObjects being built, and return it. */
static QObject *qmp_output_pop(QmpOutputVisitor *qov)
{
QStackEntry *e = QTAILQ_FIRST(&qov->stack);
QObject *value;
assert(e);
QTAILQ_REMOVE(&qov->stack, e, node);
value = e->value;
assert(value);
g_free(e);
return value;
}
/* Add @value to the current QObject being built.
* If the stack is visiting a dictionary or list, @value is now owned
* by that container. Otherwise, @value is now the root. */
static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
QObject *value)
{
QStackEntry *e = QTAILQ_FIRST(&qov->stack);
QObject *cur = e ? e->value : NULL;
if (!cur) {
/* FIXME we should require the user to reset the visitor, rather
* than throwing away the previous root */
qobject_decref(qov->root);
qov->root = value;
} else {
switch (qobject_type(cur)) {
case QTYPE_QDICT:
assert(name);
qdict_put_obj(qobject_to_qdict(cur), name, value);
break;
case QTYPE_QLIST:
qlist_append_obj(qobject_to_qlist(cur), value);
break;
default:
g_assert_not_reached();
}
}
}
static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
size_t unused, Error **errp)
{
QmpOutputVisitor *qov = to_qov(v);
QDict *dict = qdict_new();
qmp_output_add(qov, name, dict);
qmp_output_push(qov, dict);
}
static void qmp_output_end_struct(Visitor *v, Error **errp)
{
QmpOutputVisitor *qov = to_qov(v);
qmp_output_pop(qov);
}
static void qmp_output_start_list(Visitor *v, const char *name, Error **errp)
{
QmpOutputVisitor *qov = to_qov(v);
QList *list = qlist_new();
qmp_output_add(qov, name, list);
qmp_output_push(qov, list);
}
qapi: Adjust layout of FooList types By sticking the next pointer first, we don't need a union with 64-bit padding for smaller types. On 32-bit platforms, this can reduce the size of uint8List from 16 bytes (or 12, depending on whether 64-bit ints can tolerate 4-byte alignment) down to 8. It has no effect on 64-bit platforms (where alignment still dictates a 16-byte struct); but fewer anonymous unions is still a win in my book. It requires visit_next_list() to gain a size parameter, to know what size element to allocate; comparable to the size parameter of visit_start_struct(). I debated about going one step further, to allow for fewer casts, by doing: typedef GenericList GenericList; struct GenericList { GenericList *next; }; struct FooList { GenericList base; Foo *value; }; so that you convert to 'GenericList *' by '&foolist->base', and back by 'container_of(generic, GenericList, base)' (as opposed to the existing '(GenericList *)foolist' and '(FooList *)generic'). But doing that would require hoisting the declaration of GenericList prior to inclusion of qapi-types.h, rather than its current spot in visitor.h; it also makes iteration a bit more verbose through 'foolist->base.next' instead of 'foolist->next'. Note that for lists of objects, the 'value' payload is still hidden behind a boxed pointer. Someday, it would be nice to do: struct FooList { FooList *next; Foo value; }; for one less level of malloc for each list element. This patch is a step in that direction (now that 'next' is no longer at a fixed non-zero offset within the struct, we can store more than just a pointer's-worth of data as the value payload), but the actual conversion would be a task for another series, as it will touch a lot of code. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1455778109-6278-10-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-02-18 09:48:23 +03:00
static GenericList *qmp_output_next_list(Visitor *v, GenericList **listp,
size_t size)
{
GenericList *list = *listp;
QmpOutputVisitor *qov = to_qov(v);
QStackEntry *e = QTAILQ_FIRST(&qov->stack);
assert(e);
if (e->is_list_head) {
e->is_list_head = false;
return list;
}
return list ? list->next : NULL;
}
static void qmp_output_end_list(Visitor *v)
{
QmpOutputVisitor *qov = to_qov(v);
qmp_output_pop(qov);
}
static void qmp_output_type_int64(Visitor *v, const char *name, int64_t *obj,
Error **errp)
{
QmpOutputVisitor *qov = to_qov(v);
qmp_output_add(qov, name, qint_from_int(*obj));
}
static void qmp_output_type_uint64(Visitor *v, const char *name, uint64_t *obj,
Error **errp)
{
/* FIXME: QMP outputs values larger than INT64_MAX as negative */
QmpOutputVisitor *qov = to_qov(v);
qmp_output_add(qov, name, qint_from_int(*obj));
}
static void qmp_output_type_bool(Visitor *v, const char *name, bool *obj,
Error **errp)
{
QmpOutputVisitor *qov = to_qov(v);
qmp_output_add(qov, name, qbool_from_bool(*obj));
}
static void qmp_output_type_str(Visitor *v, const char *name, char **obj,
Error **errp)
{
QmpOutputVisitor *qov = to_qov(v);
if (*obj) {
qmp_output_add(qov, name, qstring_from_str(*obj));
} else {
qmp_output_add(qov, name, qstring_from_str(""));
}
}
static void qmp_output_type_number(Visitor *v, const char *name, double *obj,
Error **errp)
{
QmpOutputVisitor *qov = to_qov(v);
qmp_output_add(qov, name, qfloat_from_double(*obj));
}
static void qmp_output_type_any(Visitor *v, const char *name, QObject **obj,
Error **errp)
{
QmpOutputVisitor *qov = to_qov(v);
qobject_incref(*obj);
qmp_output_add_obj(qov, name, *obj);
}
/* Finish building, and return the root object. Will not be NULL. */
QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
{
/* FIXME: we should require that a visit occurred, and that it is
* complete (no starts without a matching end) */
QObject *obj = qov->root;
if (obj) {
qobject_incref(obj);
} else {
obj = qnull();
}
return obj;
}
Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)
{
return &v->visitor;
}
void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
{
QStackEntry *e, *tmp;
QTAILQ_FOREACH_SAFE(e, &v->stack, node, tmp) {
QTAILQ_REMOVE(&v->stack, e, node);
g_free(e);
}
qobject_decref(v->root);
g_free(v);
}
QmpOutputVisitor *qmp_output_visitor_new(void)
{
QmpOutputVisitor *v;
v = g_malloc0(sizeof(*v));
v->visitor.start_struct = qmp_output_start_struct;
v->visitor.end_struct = qmp_output_end_struct;
v->visitor.start_list = qmp_output_start_list;
v->visitor.next_list = qmp_output_next_list;
v->visitor.end_list = qmp_output_end_list;
v->visitor.type_enum = output_type_enum;
v->visitor.type_int64 = qmp_output_type_int64;
v->visitor.type_uint64 = qmp_output_type_uint64;
v->visitor.type_bool = qmp_output_type_bool;
v->visitor.type_str = qmp_output_type_str;
v->visitor.type_number = qmp_output_type_number;
v->visitor.type_any = qmp_output_type_any;
QTAILQ_INIT(&v->stack);
return v;
}