qapi/qapi-dealloc-visitor.c

   1 /*
   2  * Dealloc Visitor
   3  *
   4  * Copyright (C) 2012-2016 Red Hat, Inc.
   5  * Copyright IBM, Corp. 2011
   6  *
   7  * Authors:
   8  *  Michael Roth   <mdroth@linux.vnet.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/dealloc-visitor.h"
  17 #include "qemu/queue.h"
  18 #include "qemu-common.h"
  19 #include "qapi/qmp/types.h"
  20 #include "qapi/visitor-impl.h"
  21
  22 typedef struct StackEntry
  23 {
  24     void *value;
  25     bool is_list_head;
  26     QTAILQ_ENTRY(StackEntry) node;
  27 } StackEntry;
  28
  29 struct QapiDeallocVisitor
  30 {
  31     Visitor visitor;
  32     QTAILQ_HEAD(, StackEntry) stack;
  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, const char *name, void **obj,
  64                                       size_t unused, Error **errp)
  65 {
  66     QapiDeallocVisitor *qov = to_qov(v);
  67     qapi_dealloc_push(qov, obj);
  68 }
  69
  70 static void qapi_dealloc_end_struct(Visitor *v, Error **errp)
  71 {
  72     QapiDeallocVisitor *qov = to_qov(v);
  73     void **obj = qapi_dealloc_pop(qov);
  74     if (obj) {
  75         g_free(*obj);
  76     }
  77 }
  78
  79 static void qapi_dealloc_start_implicit_struct(Visitor *v,
  80                                                void **obj,
  81                                                size_t size,
  82                                                Error **errp)
  83 {
  84     QapiDeallocVisitor *qov = to_qov(v);
  85     qapi_dealloc_push(qov, obj);
  86 }
  87
  88 static void qapi_dealloc_end_implicit_struct(Visitor *v)
  89 {
  90     QapiDeallocVisitor *qov = to_qov(v);
  91     void **obj = qapi_dealloc_pop(qov);
  92     if (obj) {
  93         g_free(*obj);
  94     }
  95 }
  96
  97 static void qapi_dealloc_start_list(Visitor *v, const char *name, Error **errp)
  98 {
  99     QapiDeallocVisitor *qov = to_qov(v);
 100     qapi_dealloc_push(qov, NULL);
 101 }
 102
 103 static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList **listp)
 104 {
 105     GenericList *list = *listp;
 106     QapiDeallocVisitor *qov = to_qov(v);
 107     StackEntry *e = QTAILQ_FIRST(&qov->stack);
 108
 109     if (e && e->is_list_head) {
 110         e->is_list_head = false;
 111         return list;
 112     }
 113
 114     if (list) {
 115         list = list->next;
 116         g_free(*listp);
 117         return list;
 118     }
 119
 120     return NULL;
 121 }
 122
 123 static void qapi_dealloc_end_list(Visitor *v)
 124 {
 125     QapiDeallocVisitor *qov = to_qov(v);
 126     void *obj = qapi_dealloc_pop(qov);
 127     assert(obj == NULL); /* should've been list head tracker with no payload */
 128 }
 129
 130 static void qapi_dealloc_type_str(Visitor *v, const char *name, char **obj,
 131                                   Error **errp)
 132 {
 133     if (obj) {
 134         g_free(*obj);
 135     }
 136 }
 137
 138 static void qapi_dealloc_type_int64(Visitor *v, const char *name, int64_t *obj,
 139                                     Error **errp)
 140 {
 141 }
 142
 143 static void qapi_dealloc_type_uint64(Visitor *v, const char *name,
 144                                      uint64_t *obj, Error **errp)
 145 {
 146 }
 147
 148 static void qapi_dealloc_type_bool(Visitor *v, const char *name, bool *obj,
 149                                    Error **errp)
 150 {
 151 }
 152
 153 static void qapi_dealloc_type_number(Visitor *v, const char *name, double *obj,
 154                                      Error **errp)
 155 {
 156 }
 157
 158 static void qapi_dealloc_type_anything(Visitor *v, const char *name,
 159                                        QObject **obj, Error **errp)
 160 {
 161     if (obj) {
 162         qobject_decref(*obj);
 163     }
 164 }
 165
 166 static void qapi_dealloc_type_enum(Visitor *v, const char *name, int *obj,
 167                                    const char * const strings[], Error **errp)
 168 {
 169 }
 170
 171 /* If there's no data present, the dealloc visitor has nothing to free.
 172  * Thus, indicate to visitor code that the subsequent union fields can
 173  * be skipped. This is not an error condition, since the cleanup of the
 174  * rest of an object can continue unhindered, so leave errp unset in
 175  * these cases.
 176  *
 177  * NOTE: In cases where we're attempting to deallocate an object that
 178  * may have missing fields, the field indicating the union type may
 179  * be missing. In such a case, it's possible we don't have enough
 180  * information to differentiate data_present == false from a case where
 181  * data *is* present but happens to be a scalar with a value of 0.
 182  * This is okay, since in the case of the dealloc visitor there's no
 183  * work that needs to done in either situation.
 184  *
 185  * The current inability in QAPI code to more thoroughly verify a union
 186  * type in such cases will likely need to be addressed if we wish to
 187  * implement this interface for other types of visitors in the future,
 188  * however.
 189  */
 190 static bool qapi_dealloc_start_union(Visitor *v, bool data_present,
 191                                      Error **errp)
 192 {
 193     return data_present;
 194 }
 195
 196 Visitor *qapi_dealloc_get_visitor(QapiDeallocVisitor *v)
 197 {
 198     return &v->visitor;
 199 }
 200
 201 void qapi_dealloc_visitor_cleanup(QapiDeallocVisitor *v)
 202 {
 203     g_free(v);
 204 }
 205
 206 QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
 207 {
 208     QapiDeallocVisitor *v;
 209
 210     v = g_malloc0(sizeof(*v));
 211
 212     v->visitor.start_struct = qapi_dealloc_start_struct;
 213     v->visitor.end_struct = qapi_dealloc_end_struct;
 214     v->visitor.start_implicit_struct = qapi_dealloc_start_implicit_struct;
 215     v->visitor.end_implicit_struct = qapi_dealloc_end_implicit_struct;
 216     v->visitor.start_list = qapi_dealloc_start_list;
 217     v->visitor.next_list = qapi_dealloc_next_list;
 218     v->visitor.end_list = qapi_dealloc_end_list;
 219     v->visitor.type_enum = qapi_dealloc_type_enum;
 220     v->visitor.type_int64 = qapi_dealloc_type_int64;
 221     v->visitor.type_uint64 = qapi_dealloc_type_uint64;
 222     v->visitor.type_bool = qapi_dealloc_type_bool;
 223     v->visitor.type_str = qapi_dealloc_type_str;
 224     v->visitor.type_number = qapi_dealloc_type_number;
 225     v->visitor.type_any = qapi_dealloc_type_anything;
 226     v->visitor.start_union = qapi_dealloc_start_union;
 227
 228     QTAILQ_INIT(&v->stack);
 229
 230     return v;
 231 }