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 #include <babeltrace/align.h>
  31
  32 #define OBJSTACK_INIT_LEN               128
  33 #define OBJSTACK_POISON                 0xcc
  34
  35 struct objstack {
  36         struct bt_list_head head;       /* list of struct objstack_node */
  37 };
  38
  39 struct objstack_node {
  40         struct bt_list_head node;
  41         size_t len;
  42         size_t used_len;
  43         char __attribute__ ((aligned (sizeof(void *)))) data[];
  44 };
  45
  46 BT_HIDDEN
  47 struct objstack *objstack_create(void)
  48 {
  49         struct objstack *objstack;
  50         struct objstack_node *node;
  51
  52         objstack = calloc(1, sizeof(*objstack));
  53         if (!objstack)
  54                 return NULL;
  55         node = calloc(sizeof(struct objstack_node) + OBJSTACK_INIT_LEN,
  56                         sizeof(char));
  57         if (!node) {
  58                 free(objstack);
  59                 return NULL;
  60         }
  61         BT_INIT_LIST_HEAD(&objstack->head);
  62         bt_list_add_tail(&node->node, &objstack->head);
  63         node->len = OBJSTACK_INIT_LEN;
  64         return objstack;
  65 }
  66
  67 static
  68 void objstack_node_free(struct objstack_node *node)
  69 {
  70         size_t offset, len;
  71         char *p;
  72
  73         if (!node)
  74                 return;
  75         p = (char *) node;
  76         len = sizeof(*node) + node->len;
  77         for (offset = 0; offset < len; offset++)
  78                 p[offset] = OBJSTACK_POISON;
  79         free(node);
  80 }
  81
  82 BT_HIDDEN
  83 void objstack_destroy(struct objstack *objstack)
  84 {
  85         struct objstack_node *node, *p;
  86
  87         if (!objstack)
  88                 return;
  89         bt_list_for_each_entry_safe(node, p, &objstack->head, node) {
  90                 bt_list_del(&node->node);
  91                 objstack_node_free(node);
  92         }
  93         free(objstack);
  94 }
  95
  96 static
  97 struct objstack_node *objstack_append_node(struct objstack *objstack)
  98 {
  99         struct objstack_node *last_node, *new_node;
 100
 101         /* Get last node */
 102         last_node = bt_list_entry(objstack->head.prev,
 103                         struct objstack_node, node);
 104
 105         /* Allocate new node with double of size of last node */
 106         new_node = calloc(sizeof(struct objstack_node) + (last_node->len << 1),
 107                         sizeof(char));
 108         if (!new_node) {
 109                 return NULL;
 110         }
 111         bt_list_add_tail(&new_node->node, &objstack->head);
 112         new_node->len = last_node->len << 1;
 113         return new_node;
 114 }
 115
 116 BT_HIDDEN
 117 void *objstack_alloc(struct objstack *objstack, size_t len)
 118 {
 119         struct objstack_node *last_node;
 120         void *p;
 121
 122         len = ALIGN(len, sizeof(void *));
 123
 124         /* Get last node */
 125         last_node = bt_list_entry(objstack->head.prev,
 126                         struct objstack_node, node);
 127         while (last_node->len - last_node->used_len < len) {
 128                 last_node = objstack_append_node(objstack);
 129                 if (!last_node) {
 130                         return NULL;
 131                 }
 132         }
 133         p = &last_node->data[last_node->used_len];
 134         last_node->used_len += len;
 135         return p;
 136 }