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_ALIGN                  8       /* Object stack alignment */
  33 #define OBJSTACK_INIT_LEN               128
  34 #define OBJSTACK_POISON                 0xcc
  35
  36 struct objstack {
  37         struct bt_list_head head;       /* list of struct objstack_node */
  38 };
  39
  40 struct objstack_node {
  41         struct bt_list_head node;
  42         size_t len;
  43         size_t used_len;
  44         char __attribute__ ((aligned (OBJSTACK_ALIGN))) data[];
  45 };
  46
  47 BT_HIDDEN
  48 struct objstack *objstack_create(void)
  49 {
  50         struct objstack *objstack;
  51         struct objstack_node *node;
  52
  53         objstack = calloc(1, sizeof(*objstack));
  54         if (!objstack)
  55                 return NULL;
  56         node = calloc(sizeof(struct objstack_node) + OBJSTACK_INIT_LEN,
  57                         sizeof(char));
  58         if (!node) {
  59                 free(objstack);
  60                 return NULL;
  61         }
  62         BT_INIT_LIST_HEAD(&objstack->head);
  63         bt_list_add_tail(&node->node, &objstack->head);
  64         node->len = OBJSTACK_INIT_LEN;
  65         return objstack;
  66 }
  67
  68 static
  69 void objstack_node_free(struct objstack_node *node)
  70 {
  71         size_t offset, len;
  72         char *p;
  73
  74         if (!node)
  75                 return;
  76         p = (char *) node;
  77         len = sizeof(*node) + node->len;
  78         for (offset = 0; offset < len; offset++)
  79                 p[offset] = OBJSTACK_POISON;
  80         free(node);
  81 }
  82
  83 BT_HIDDEN
  84 void objstack_destroy(struct objstack *objstack)
  85 {
  86         struct objstack_node *node, *p;
  87
  88         if (!objstack)
  89                 return;
  90         bt_list_for_each_entry_safe(node, p, &objstack->head, node) {
  91                 bt_list_del(&node->node);
  92                 objstack_node_free(node);
  93         }
  94         free(objstack);
  95 }
  96
  97 static
  98 struct objstack_node *objstack_append_node(struct objstack *objstack)
  99 {
 100         struct objstack_node *last_node, *new_node;
 101
 102         /* Get last node */
 103         last_node = bt_list_entry(objstack->head.prev,
 104                         struct objstack_node, node);
 105
 106         /* Allocate new node with double of size of last node */
 107         new_node = calloc(sizeof(struct objstack_node) + (last_node->len << 1),
 108                         sizeof(char));
 109         if (!new_node) {
 110                 return NULL;
 111         }
 112         bt_list_add_tail(&new_node->node, &objstack->head);
 113         new_node->len = last_node->len << 1;
 114         return new_node;
 115 }
 116
 117 BT_HIDDEN
 118 void *objstack_alloc(struct objstack *objstack, size_t len)
 119 {
 120         struct objstack_node *last_node;
 121         void *p;
 122
 123         len = ALIGN(len, OBJSTACK_ALIGN);
 124
 125         /* Get last node */
 126         last_node = bt_list_entry(objstack->head.prev,
 127                         struct objstack_node, node);
 128         while (last_node->len - last_node->used_len < len) {
 129                 last_node = objstack_append_node(objstack);
 130                 if (!last_node) {
 131                         return NULL;
 132                 }
 133         }
 134         p = &last_node->data[last_node->used_len];
 135         last_node->used_len += len;
 136         return p;
 137 }