qapi/qapi-dealloc-visitor.c

   1 /*
   2  * Dealloc Visitor
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *  Michael Roth   <mdroth@linux.vnet.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
  10  * See the COPYING.LIB file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu/osdep.h"
  15 #include "qapi/dealloc-visitor.h"
  16 #include "qemu/queue.h"
  17 #include "qemu-common.h"
  18 #include "qapi/qmp/types.h"
  19 #include "qapi/visitor-impl.h"
  20
  21 typedef struct StackEntry
  22 {
  23     void *value;
  24     bool is_list_head;
  25     QTAILQ_ENTRY(StackEntry) node;
  26 } StackEntry;
  27
  28 struct QapiDeallocVisitor
  29 {
  30     Visitor visitor;
  31     QTAILQ_HEAD(, StackEntry) stack;
  32     bool is_list_head;
  33 };
  34
  35 static QapiDeallocVisitor *to_qov(Visitor *v)
  36 {
  37     return container_of(v, QapiDeallocVisitor, visitor);
  38 }
  39
  40 static void qapi_dealloc_push(QapiDeallocVisitor *qov, void *value)
  41 {
  42     StackEntry *e = g_malloc0(sizeof(*e));
  43
  44     e->value = value;
  45
  46     /* see if we're just pushing a list head tracker */
  47     if (value == NULL) {
  48         e->is_list_head = true;
  49     }
  50     QTAILQ_INSERT_HEAD(&qov->stack, e, node);
  51 }
  52
  53 static void *qapi_dealloc_pop(QapiDeallocVisitor *qov)
  54 {
  55     StackEntry *e = QTAILQ_FIRST(&qov->stack);
  56     QObject *value;
  57     QTAILQ_REMOVE(&qov->stack, e, node);
  58     value = e->value;
  59     g_free(e);
  60     return value;
  61 }
  62
  63 static void qapi_dealloc_start_struct(Visitor *v, void **obj, const char *kind,
  64                                       const char *name, size_t unused,
  65                                       Error **errp)
  66 {
  67     QapiDeallocVisitor *qov = to_qov(v);
  68     qapi_dealloc_push(qov, obj);
  69 }
  70
  71 static void qapi_dealloc_end_struct(Visitor *v, Error **errp)
  72 {
  73     QapiDeallocVisitor *qov = to_qov(v);
  74     void **obj = qapi_dealloc_pop(qov);
  75     if (obj) {
  76         g_free(*obj);
  77     }
  78 }
  79
  80 static void qapi_dealloc_start_implicit_struct(Visitor *v,
  81                                                void **obj,
  82                                                size_t size,
  83                                                Error **errp)
  84 {
  85     QapiDeallocVisitor *qov = to_qov(v);
  86     qapi_dealloc_push(qov, obj);
  87 }
  88
  89 static void qapi_dealloc_end_implicit_struct(Visitor *v, Error **errp)
  90 {
  91     QapiDeallocVisitor *qov = to_qov(v);
  92     void **obj = qapi_dealloc_pop(qov);
  93     if (obj) {
  94         g_free(*obj);
  95     }
  96 }
  97
  98 static void qapi_dealloc_start_list(Visitor *v, const char *name, Error **errp)
  99 {
 100     QapiDeallocVisitor *qov = to_qov(v);
 101     qapi_dealloc_push(qov, NULL);
 102 }
 103
 104 static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList **listp,
 105                                            Error **errp)
 106 {
 107     GenericList *list = *listp;
 108     QapiDeallocVisitor *qov = to_qov(v);
 109     StackEntry *e = QTAILQ_FIRST(&qov->stack);
 110
 111     if (e && e->is_list_head) {
 112         e->is_list_head = false;
 113         return list;
 114     }
 115
 116     if (list) {
 117         list = list->next;
 118         g_free(*listp);
 119         return list;
 120     }
 121
 122     return NULL;
 123 }
 124
 125 static void qapi_dealloc_end_list(Visitor *v, Error **errp)
 126 {
 127     QapiDeallocVisitor *qov = to_qov(v);
 128     void *obj = qapi_dealloc_pop(qov);
 129     assert(obj == NULL); /* should've been list head tracker with no payload */
 130 }
 131
 132 static void qapi_dealloc_type_str(Visitor *v, char **obj, const char *name,
 133                                   Error **errp)
 134 {
 135     if (obj) {
 136         g_free(*obj);
 137     }
 138 }
 139
 140 static void qapi_dealloc_type_int(Visitor *v, int64_t *obj, const char *name,
 141                                   Error **errp)
 142 {
 143 }
 144
 145 static void qapi_dealloc_type_bool(Visitor *v, bool *obj, const char *name,
 146                                    Error **errp)
 147 {
 148 }
 149
 150 static void qapi_dealloc_type_number(Visitor *v, double *obj, const char *name,
 151                                      Error **errp)
 152 {
 153 }
 154
 155 static void qapi_dealloc_type_anything(Visitor *v, QObject **obj,
 156                                        const char *name, Error **errp)
 157 {
 158     if (obj) {
 159         qobject_decref(*obj);
 160     }
 161 }
 162
 163 static void qapi_dealloc_type_size(Visitor *v, uint64_t *obj, const char *name,
 164                                    Error **errp)
 165 {
 166 }
 167
 168 static void qapi_dealloc_type_enum(Visitor *v, int *obj,
 169                                    const char * const strings[],
 170                                    const char *kind, const char *name,
 171                                    Error **errp)
 172 {
 173 }
 174
 175 /* If there's no data present, the dealloc visitor has nothing to free.
 176  * Thus, indicate to visitor code that the subsequent union fields can
 177  * be skipped. This is not an error condition, since the cleanup of the
 178  * rest of an object can continue unhindered, so leave errp unset in
 179  * these cases.
 180  *
 181  * NOTE: In cases where we're attempting to deallocate an object that
 182  * may have missing fields, the field indicating the union type may
 183  * be missing. In such a case, it's possible we don't have enough
 184  * information to differentiate data_present == false from a case where
 185  * data *is* present but happens to be a scalar with a value of 0.
 186  * This is okay, since in the case of the dealloc visitor there's no
 187  * work that needs to done in either situation.
 188  *
 189  * The current inability in QAPI code to more thoroughly verify a union
 190  * type in such cases will likely need to be addressed if we wish to
 191  * implement this interface for other types of visitors in the future,
 192  * however.
 193  */
 194 static bool qapi_dealloc_start_union(Visitor *v, bool data_present,
 195                                      Error **errp)
 196 {
 197     return data_present;
 198 }
 199
 200 Visitor *qapi_dealloc_get_visitor(QapiDeallocVisitor *v)
 201 {
 202     return &v->visitor;
 203 }
 204
 205 void qapi_dealloc_visitor_cleanup(QapiDeallocVisitor *v)
 206 {
 207     g_free(v);
 208 }
 209
 210 QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
 211 {
 212     QapiDeallocVisitor *v;
 213
 214     v = g_malloc0(sizeof(*v));
 215
 216     v->visitor.start_struct = qapi_dealloc_start_struct;
 217     v->visitor.end_struct = qapi_dealloc_end_struct;
 218     v->visitor.start_implicit_struct = qapi_dealloc_start_implicit_struct;
 219     v->visitor.end_implicit_struct = qapi_dealloc_end_implicit_struct;
 220     v->visitor.start_list = qapi_dealloc_start_list;
 221     v->visitor.next_list = qapi_dealloc_next_list;
 222     v->visitor.end_list = qapi_dealloc_end_list;
 223     v->visitor.type_enum = qapi_dealloc_type_enum;
 224     v->visitor.type_int = qapi_dealloc_type_int;
 225     v->visitor.type_bool = qapi_dealloc_type_bool;
 226     v->visitor.type_str = qapi_dealloc_type_str;
 227     v->visitor.type_number = qapi_dealloc_type_number;
 228     v->visitor.type_any = qapi_dealloc_type_anything;
 229     v->visitor.type_size = qapi_dealloc_type_size;
 230     v->visitor.start_union = qapi_dealloc_start_union;
 231
 232     QTAILQ_INIT(&v->stack);
 233
 234     return v;
 235 }