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/*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
/** Functions which we wish were included in the standard talloc distribution
*
* @file src/lib/talloc.c
*
* @copyright 2017 The FreeRADIUS server project
* @copyright 2017 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
*/
RCSID("$Id$")
#include <freeradius-devel/math.h>
#include <freeradius-devel/libradius.h>
#include <freeradius-devel/talloc.h>
/** Return a page aligned talloc memory array
*
* Because we can't intercept talloc's malloc() calls, we need to do some tricks
* in order to get the first allocation in the array page aligned, and to limit
* the size of the array to a multiple of the page size.
*
* The reason for wanting a page aligned talloc array, is it allows us to
* mprotect() the pages that belong to the array.
*
* Talloc chunks appear to be allocated within the protected region, so this should
* catch frees too.
*
* @param[in] ctx to allocate array memory in.
* @param[out] start The first aligned address in the array.
* @param[in] alignment What alignment the memory chunk should have.
* @param[in] size How big to make the array. Will be corrected to a multiple
* of the page size. The actual array size will be size
* rounded to a multiple of the (page_size), + page_size
* @return
* - A talloc chunk on success.
* - NULL on failure.
*/
TALLOC_CTX *talloc_aligned_array(TALLOC_CTX *ctx, void **start, size_t alignment, size_t size)
{
size_t rounded;
size_t array_size;
void *next;
TALLOC_CTX *array;
rounded = ROUND_UP(size, alignment); /* Round up to a multiple of the page size */
if (rounded == 0) rounded = alignment;
array_size = rounded + alignment;
array = talloc_array(ctx, uint8_t, array_size); /* Over allocate */
if (!array) {
fr_strerror_printf("Out of memory");
return NULL;
}
next = (void *)ROUND_UP((uintptr_t)array, alignment); /* Round up address to the next multiple */
*start = next;
return array;
}
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