formats/ctf/metadata/objstack.c

   1 /*
   2  * objstack.c
   3  *
   4  * Common Trace Format Object Stack.
   5  *
   6  * Copyright 2013 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a copy
   9  * of this software and associated documentation files (the "Software"), to deal
  10  * in the Software without restriction, including without limitation the rights
  11  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12  * copies of the Software, and to permit persons to whom the Software is
  13  * furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  24  * SOFTWARE.
  25  */
  26
  27 #include <stdlib.h>
  28 #include <babeltrace/list.h>
  29 #include <babeltrace/babeltrace-internal.h>
  30
  31 #define OBJSTACK_INIT_LEN               128
  32 #define OBJSTACK_POISON                 0xcc
  33
  34 struct objstack {
  35         struct bt_list_head head;       /* list of struct objstack_node */
  36 };
  37
  38 struct objstack_node {
  39         struct bt_list_head node;
  40         size_t len;
  41         size_t used_len;
  42         char data[];
  43 };
  44
  45 BT_HIDDEN
  46 struct objstack *objstack_create(void)
  47 {
  48         struct objstack *objstack;
  49         struct objstack_node *node;
  50
  51         objstack = calloc(1, sizeof(*objstack));
  52         if (!objstack)
  53                 return NULL;
  54         node = calloc(sizeof(struct objstack_node) + OBJSTACK_INIT_LEN,
  55                         sizeof(char));
  56         if (!node) {
  57                 free(objstack);
  58                 return NULL;
  59         }
  60         BT_INIT_LIST_HEAD(&objstack->head);
  61         bt_list_add_tail(&node->node, &objstack->head);
  62         node->len = OBJSTACK_INIT_LEN;
  63         return objstack;
  64 }
  65
  66 static
  67 void objstack_node_free(struct objstack_node *node)
  68 {
  69         size_t offset, len;
  70         char *p;
  71
  72         if (!node)
  73                 return;
  74         p = (char *) node;
  75         len = sizeof(*node) + node->len;
  76         for (offset = 0; offset < len; offset++)
  77                 p[offset] = OBJSTACK_POISON;
  78         free(node);
  79 }
  80
  81 BT_HIDDEN
  82 void objstack_destroy(struct objstack *objstack)
  83 {
  84         struct objstack_node *node, *p;
  85
  86         if (!objstack)
  87                 return;
  88         bt_list_for_each_entry_safe(node, p, &objstack->head, node) {
  89                 bt_list_del(&node->node);
  90                 objstack_node_free(node);
  91         }
  92         free(objstack);
  93 }
  94
  95 static
  96 struct objstack_node *objstack_append_node(struct objstack *objstack)
  97 {
  98         struct objstack_node *last_node, *new_node;
  99
 100         /* Get last node */
 101         last_node = bt_list_entry(objstack->head.prev,
 102                         struct objstack_node, node);
 103
 104         /* Allocate new node with double of size of last node */
 105         new_node = calloc(sizeof(struct objstack_node) + (last_node->len << 1),
 106                         sizeof(char));
 107         if (!new_node) {
 108                 return NULL;
 109         }
 110         bt_list_add_tail(&new_node->node, &objstack->head);
 111         new_node->len = last_node->len << 1;
 112         return new_node;
 113 }
 114
 115 BT_HIDDEN
 116 void *objstack_alloc(struct objstack *objstack, size_t len)
 117 {
 118         struct objstack_node *last_node;
 119         void *p;
 120
 121         /* Get last node */
 122         last_node = bt_list_entry(objstack->head.prev,
 123                         struct objstack_node, node);
 124         while (last_node->len - last_node->used_len < len) {
 125                 last_node = objstack_append_node(objstack);
 126                 if (!last_node) {
 127                         return NULL;
 128                 }
 129         }
 130         p = &last_node->data[last_node->used_len];
 131         last_node->used_len += len;
 132         return p;
 133 }