qapi/qmp-output-visitor.c

   1 /*
   2  * Core Definitions for QAPI/QMP Command Registry
   3  *
   4  * Copyright (C) 2012-2016 Red Hat, Inc.
   5  * Copyright IBM, Corp. 2011
   6  *
   7  * Authors:
   8  *  Anthony Liguori   <aliguori@us.ibm.com>
   9  *
  10  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
  11  * See the COPYING.LIB file in the top-level directory.
  12  *
  13  */
  14
  15 #include "qemu/osdep.h"
  16 #include "qapi/qmp-output-visitor.h"
  17 #include "qapi/visitor-impl.h"
  18 #include "qemu/queue.h"
  19 #include "qemu-common.h"
  20 #include "qapi/qmp/types.h"
  21
  22 typedef struct QStackEntry
  23 {
  24     QObject *value;
  25     bool is_list_head;
  26     QTAILQ_ENTRY(QStackEntry) node;
  27 } QStackEntry;
  28
  29 typedef QTAILQ_HEAD(QStack, QStackEntry) QStack;
  30
  31 struct QmpOutputVisitor
  32 {
  33     Visitor visitor;
  34     QStack stack; /* Stack of containers that haven't yet been finished */
  35     QObject *root; /* Root of the output visit */
  36 };
  37
  38 #define qmp_output_add(qov, name, value) \
  39     qmp_output_add_obj(qov, name, QOBJECT(value))
  40 #define qmp_output_push(qov, value) qmp_output_push_obj(qov, QOBJECT(value))
  41
  42 static QmpOutputVisitor *to_qov(Visitor *v)
  43 {
  44     return container_of(v, QmpOutputVisitor, visitor);
  45 }
  46
  47 /* Push @value onto the stack of current QObjects being built */
  48 static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
  49 {
  50     QStackEntry *e = g_malloc0(sizeof(*e));
  51
  52     assert(qov->root);
  53     assert(value);
  54     e->value = value;
  55     if (qobject_type(e->value) == QTYPE_QLIST) {
  56         e->is_list_head = true;
  57     }
  58     QTAILQ_INSERT_HEAD(&qov->stack, e, node);
  59 }
  60
  61 /* Pop a value off the stack of QObjects being built, and return it. */
  62 static QObject *qmp_output_pop(QmpOutputVisitor *qov)
  63 {
  64     QStackEntry *e = QTAILQ_FIRST(&qov->stack);
  65     QObject *value;
  66
  67     assert(e);
  68     QTAILQ_REMOVE(&qov->stack, e, node);
  69     value = e->value;
  70     assert(value);
  71     g_free(e);
  72     return value;
  73 }
  74
  75 /* Add @value to the current QObject being built.
  76  * If the stack is visiting a dictionary or list, @value is now owned
  77  * by that container. Otherwise, @value is now the root.  */
  78 static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
  79                                QObject *value)
  80 {
  81     QStackEntry *e = QTAILQ_FIRST(&qov->stack);
  82     QObject *cur = e ? e->value : NULL;
  83
  84     if (!cur) {
  85         /* Don't allow reuse of visitor on more than one root */
  86         assert(!qov->root);
  87         qov->root = value;
  88     } else {
  89         switch (qobject_type(cur)) {
  90         case QTYPE_QDICT:
  91             assert(name);
  92             qdict_put_obj(qobject_to_qdict(cur), name, value);
  93             break;
  94         case QTYPE_QLIST:
  95             assert(!name);
  96             qlist_append_obj(qobject_to_qlist(cur), value);
  97             break;
  98         default:
  99             g_assert_not_reached();
 100         }
 101     }
 102 }
 103
 104 static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
 105                                     size_t unused, Error **errp)
 106 {
 107     QmpOutputVisitor *qov = to_qov(v);
 108     QDict *dict = qdict_new();
 109
 110     qmp_output_add(qov, name, dict);
 111     qmp_output_push(qov, dict);
 112 }
 113
 114 static void qmp_output_end_struct(Visitor *v, Error **errp)
 115 {
 116     QmpOutputVisitor *qov = to_qov(v);
 117     QObject *value = qmp_output_pop(qov);
 118     assert(qobject_type(value) == QTYPE_QDICT);
 119 }
 120
 121 static void qmp_output_start_list(Visitor *v, const char *name, Error **errp)
 122 {
 123     QmpOutputVisitor *qov = to_qov(v);
 124     QList *list = qlist_new();
 125
 126     qmp_output_add(qov, name, list);
 127     qmp_output_push(qov, list);
 128 }
 129
 130 static GenericList *qmp_output_next_list(Visitor *v, GenericList **listp,
 131                                          size_t size)
 132 {
 133     GenericList *list = *listp;
 134     QmpOutputVisitor *qov = to_qov(v);
 135     QStackEntry *e = QTAILQ_FIRST(&qov->stack);
 136
 137     assert(e);
 138     if (e->is_list_head) {
 139         e->is_list_head = false;
 140         return list;
 141     }
 142
 143     return list ? list->next : NULL;
 144 }
 145
 146 static void qmp_output_end_list(Visitor *v)
 147 {
 148     QmpOutputVisitor *qov = to_qov(v);
 149     QObject *value = qmp_output_pop(qov);
 150     assert(qobject_type(value) == QTYPE_QLIST);
 151 }
 152
 153 static void qmp_output_type_int64(Visitor *v, const char *name, int64_t *obj,
 154                                   Error **errp)
 155 {
 156     QmpOutputVisitor *qov = to_qov(v);
 157     qmp_output_add(qov, name, qint_from_int(*obj));
 158 }
 159
 160 static void qmp_output_type_uint64(Visitor *v, const char *name, uint64_t *obj,
 161                                    Error **errp)
 162 {
 163     /* FIXME: QMP outputs values larger than INT64_MAX as negative */
 164     QmpOutputVisitor *qov = to_qov(v);
 165     qmp_output_add(qov, name, qint_from_int(*obj));
 166 }
 167
 168 static void qmp_output_type_bool(Visitor *v, const char *name, bool *obj,
 169                                  Error **errp)
 170 {
 171     QmpOutputVisitor *qov = to_qov(v);
 172     qmp_output_add(qov, name, qbool_from_bool(*obj));
 173 }
 174
 175 static void qmp_output_type_str(Visitor *v, const char *name, char **obj,
 176                                 Error **errp)
 177 {
 178     QmpOutputVisitor *qov = to_qov(v);
 179     if (*obj) {
 180         qmp_output_add(qov, name, qstring_from_str(*obj));
 181     } else {
 182         qmp_output_add(qov, name, qstring_from_str(""));
 183     }
 184 }
 185
 186 static void qmp_output_type_number(Visitor *v, const char *name, double *obj,
 187                                    Error **errp)
 188 {
 189     QmpOutputVisitor *qov = to_qov(v);
 190     qmp_output_add(qov, name, qfloat_from_double(*obj));
 191 }
 192
 193 static void qmp_output_type_any(Visitor *v, const char *name, QObject **obj,
 194                                 Error **errp)
 195 {
 196     QmpOutputVisitor *qov = to_qov(v);
 197     qobject_incref(*obj);
 198     qmp_output_add_obj(qov, name, *obj);
 199 }
 200
 201 static void qmp_output_type_null(Visitor *v, const char *name, Error **errp)
 202 {
 203     QmpOutputVisitor *qov = to_qov(v);
 204     qmp_output_add_obj(qov, name, qnull());
 205 }
 206
 207 /* Finish building, and return the root object.
 208  * The root object is never null. The caller becomes the object's
 209  * owner, and should use qobject_decref() when done with it.  */
 210 QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
 211 {
 212     /* A visit must have occurred, with each start paired with end.  */
 213     assert(qov->root && QTAILQ_EMPTY(&qov->stack));
 214
 215     qobject_incref(qov->root);
 216     return qov->root;
 217 }
 218
 219 Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)
 220 {
 221     return &v->visitor;
 222 }
 223
 224 void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
 225 {
 226     QStackEntry *e, *tmp;
 227
 228     QTAILQ_FOREACH_SAFE(e, &v->stack, node, tmp) {
 229         QTAILQ_REMOVE(&v->stack, e, node);
 230         g_free(e);
 231     }
 232
 233     qobject_decref(v->root);
 234     g_free(v);
 235 }
 236
 237 QmpOutputVisitor *qmp_output_visitor_new(void)
 238 {
 239     QmpOutputVisitor *v;
 240
 241     v = g_malloc0(sizeof(*v));
 242
 243     v->visitor.type = VISITOR_OUTPUT;
 244     v->visitor.start_struct = qmp_output_start_struct;
 245     v->visitor.end_struct = qmp_output_end_struct;
 246     v->visitor.start_list = qmp_output_start_list;
 247     v->visitor.next_list = qmp_output_next_list;
 248     v->visitor.end_list = qmp_output_end_list;
 249     v->visitor.type_int64 = qmp_output_type_int64;
 250     v->visitor.type_uint64 = qmp_output_type_uint64;
 251     v->visitor.type_bool = qmp_output_type_bool;
 252     v->visitor.type_str = qmp_output_type_str;
 253     v->visitor.type_number = qmp_output_type_number;
 254     v->visitor.type_any = qmp_output_type_any;
 255     v->visitor.type_null = qmp_output_type_null;
 256
 257     QTAILQ_INIT(&v->stack);
 258
 259     return v;
 260 }