/*

 * memory.c: safer memory allocation

 *

 * Copyright (C) 2008-2016 Daniel P. Berrange

 *

 * 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

 *

 */

#include <config.h>

#include <stdlib.h>

#include <stddef.h>

#include "memory.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.  */

# define xalloc_oversized(n, s) \

    ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))

/**

 * mem_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.

 *

 * Returns -1 on failure to allocate, zero on success

 */

int mem_alloc_n(void *ptrptr, size_t size, size_t count)

{

    if (AUGEAS_UNLIKELY(size == 0 || count == 0)) {

        *(void **)ptrptr = NULL;

        return 0;

    }

    *(void**)ptrptr = calloc(count, size);

    if (AUGEAS_UNLIKELY(*(void**)ptrptr == NULL))

        return -1;

    return 0;

}

/**

 * virReallocN:

 * @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.

 *

 * Returns -1 on failure to allocate, zero on success

 */

int mem_realloc_n(void *ptrptr, size_t size, size_t count)

{

    void *tmp;

    if (AUGEAS_UNLIKELY(size == 0 || count == 0)) {

        free(*(void **)ptrptr);

        *(void **)ptrptr = NULL;

        return 0;

    }

    if (AUGEAS_UNLIKELY(xalloc_oversized(count, size))) {

        errno = ENOMEM;

        return -1;

    }

    tmp = realloc(*(void**)ptrptr, size * count);

    if (AUGEAS_UNLIKELY(!tmp))

        return -1;

    *(void**)ptrptr = tmp;

    return 0;

}