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