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/* wmem_allocator_strict.c
* Wireshark Memory Manager Strict Allocator
* Copyright 2012, Evan Huus <eapache@gmail.com>
*
* $Id$
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <string.h>
#include <glib.h>
#include "wmem_core.h"
#include "wmem_allocator.h"
/* In this allocator, we do everything we can to catch invalid memory accesses.
* This includes using canaries (what Valgrind calls redzones) and
* filling allocated and freed memory with garbage. Valgrind is still the
* better tool on the platforms where it is available - use it instead if
* possible.
*/
#define WMEM_CANARY_SIZE 16
#define WMEM_CANARY_VALUE 0x8E
#define WMEM_PREFILL 0xA1
#define WMEM_POSTFILL 0x1A
typedef struct _wmem_strict_allocator_block_t {
/* Simple manual singly-linked list of allocations */
struct _wmem_strict_allocator_block_t *next;
/* Just the length of real_data, not counting the canaries */
gsize data_len;
guint8 *leading_canary;
guint8 *real_data;
guint8 *trailing_canary;
} wmem_strict_allocator_block_t;
typedef struct _wmem_strict_allocator_t {
wmem_strict_allocator_block_t *block_list;
} wmem_strict_allocator_t;
static void *
wmem_strict_alloc(void *private_data, const size_t size)
{
wmem_strict_allocator_t *allocator;
wmem_strict_allocator_block_t *block;
allocator = (wmem_strict_allocator_t*) private_data;
block = g_new(wmem_strict_allocator_block_t, 1);
block->data_len = size;
block->leading_canary = g_malloc(block->data_len + (2 * WMEM_CANARY_SIZE));
block->real_data = block->leading_canary + WMEM_CANARY_SIZE;
block->trailing_canary = block->real_data + block->data_len;
block->next = allocator->block_list;
allocator->block_list = block;
memset(block->leading_canary, WMEM_CANARY_VALUE, WMEM_CANARY_SIZE);
memset(block->real_data, WMEM_PREFILL, block->data_len);
memset(block->trailing_canary, WMEM_CANARY_VALUE, WMEM_CANARY_SIZE);
return block->real_data;
}
static void
wmem_strict_real_check_canaries(wmem_strict_allocator_t *allocator)
{
guint i;
wmem_strict_allocator_block_t *block;
block = allocator->block_list;
while (block) {
for (i=0; i<WMEM_CANARY_SIZE; i++) {
g_assert(block->leading_canary[i] == WMEM_CANARY_VALUE);
g_assert(block->trailing_canary[i] == WMEM_CANARY_VALUE);
}
block = block->next;
}
}
void
wmem_strict_check_canaries(wmem_allocator_t *allocator)
{
/* XXX: Should this be a g_assert() instead? This is more of a general API
* issue - should allocator-specific functions be safe to call with an
* allocator of the wrong type or not? And how should they interact with the
* WIRESHARK_DEBUG_WMEM_OVERRIDE environment variable? */
if (allocator->type != WMEM_ALLOCATOR_STRICT) {
return;
}
wmem_strict_real_check_canaries(allocator->private_data);
}
static void
wmem_strict_free_all(void *private_data)
{
wmem_strict_allocator_t *allocator;
wmem_strict_allocator_block_t *block, *tmp;
allocator = (wmem_strict_allocator_t*) private_data;
wmem_strict_real_check_canaries(allocator);
block = allocator->block_list;
while (block) {
memset(block->real_data, WMEM_POSTFILL, block->data_len);
g_free(block->leading_canary);
tmp = block;
block = block->next;
g_free(tmp);
}
allocator->block_list = NULL;
}
static void
wmem_strict_allocator_destroy(wmem_allocator_t *allocator)
{
g_free(allocator->private_data);
g_free(allocator);
}
wmem_allocator_t *
wmem_strict_allocator_new(void)
{
wmem_allocator_t *allocator;
wmem_strict_allocator_t *strict_allocator;
allocator = g_new(wmem_allocator_t, 1);
strict_allocator = g_new(wmem_strict_allocator_t, 1);
allocator->alloc = &wmem_strict_alloc;
allocator->free_all = &wmem_strict_free_all;
allocator->destroy = &wmem_strict_allocator_destroy;
allocator->private_data = (void*) strict_allocator;
strict_allocator->block_list = NULL;
return allocator;
}
/*
* Editor modelines - http://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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