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/*
* safe-alloc.c: safer memory allocation
*
* Copyright (C) 2009 Free Software Foundation, Inc.
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
/* Written by Daniel Berrange <berrange@redhat.com>, 2008 */
#include <config.h>
/* Specification. */
#include "safe-alloc.h"
#include <stdlib.h>
#include <stddef.h>
#include <errno.h>
/* Return 1 if an array of N objects, each of size S, cannot exist due
to size arithmetic overflow. S must be positive and N must be
nonnegative. This is a macro, not an inline function, so that it
works correctly even when SIZE_MAX < N.
By gnulib convention, SIZE_MAX represents overflow in size
calculations, so the conservative dividend to use here is
SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
However, malloc (SIZE_MAX) fails on all known hosts where
sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
exactly-SIZE_MAX allocations on such hosts; this avoids a test and
branch when S is known to be 1.
This is the same as xalloc_oversized from xalloc.h
*/
#define safe_alloc_oversized(n, s) \
((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
/**
* safe_alloc_alloc_n:
* @ptrptr: pointer to pointer for address of allocated memory
* @size: number of bytes to allocate
* @count: number of elements to allocate
*
* Allocate an array of memory 'count' elements long,
* each with 'size' bytes. Return the address of the
* allocated memory in 'ptrptr'. The newly allocated
* memory is filled with zeros.
*
* Return -1 on failure to allocate, zero on success
*/
int
safe_alloc_alloc_n (void *ptrptr, size_t size, size_t count, int zeroed)
{
if (size == 0 || count == 0)
{
*(void **) ptrptr = NULL;
return 0;
}
if (safe_alloc_oversized (count, size))
{
errno = ENOMEM;
return -1;
}
if (zeroed)
*(void **) ptrptr = calloc (count, size);
else
*(void **) ptrptr = malloc (count * size);
if (*(void **) ptrptr == NULL)
return -1;
return 0;
}
/**
* safe_alloc_realloc_n:
* @ptrptr: pointer to pointer for address of allocated memory
* @size: number of bytes to allocate
* @count: number of elements in array
*
* Resize the block of memory in 'ptrptr' to be an array of
* 'count' elements, each 'size' bytes in length. Update 'ptrptr'
* with the address of the newly allocated memory. On failure,
* 'ptrptr' is not changed and still points to the original memory
* block. The newly allocated memory is filled with zeros.
*
* Return -1 on failure to allocate, zero on success
*/
int
safe_alloc_realloc_n (void *ptrptr, size_t size, size_t count)
{
void *tmp;
if (size == 0 || count == 0)
{
free (*(void **) ptrptr);
*(void **) ptrptr = NULL;
return 0;
}
if (safe_alloc_oversized (count, size))
{
errno = ENOMEM;
return -1;
}
tmp = realloc (*(void **) ptrptr, size * count);
if (!tmp)
return -1;
*(void **) ptrptr = tmp;
return 0;
}
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