2 * memory.c: safer memory allocation
4 * Copyright (C) 2008-2016 Daniel P. Berrange
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
30 /* Return 1 if an array of N objects, each of size S, cannot exist due
31 to size arithmetic overflow. S must be positive and N must be
32 nonnegative. This is a macro, not an inline function, so that it
33 works correctly even when SIZE_MAX < N.
35 By gnulib convention, SIZE_MAX represents overflow in size
36 calculations, so the conservative dividend to use here is
37 SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
38 However, malloc (SIZE_MAX) fails on all known hosts where
39 sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
40 exactly-SIZE_MAX allocations on such hosts; this avoids a test and
41 branch when S is known to be 1. */
42 # define xalloc_oversized(n, s) \
43 ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
48 * @ptrptr: pointer to pointer for address of allocated memory
49 * @size: number of bytes to allocate
50 * @count: number of elements to allocate
52 * Allocate an array of memory 'count' elements long,
53 * each with 'size' bytes. Return the address of the
54 * allocated memory in 'ptrptr'. The newly allocated
55 * memory is filled with zeros.
57 * Returns -1 on failure to allocate, zero on success
59 int mem_alloc_n(void *ptrptr, size_t size, size_t count)
61 if (size == 0 || count == 0) {
62 *(void **)ptrptr = NULL;
66 *(void**)ptrptr = calloc(count, size);
67 if (*(void**)ptrptr == NULL)
74 * @ptrptr: pointer to pointer for address of allocated memory
75 * @size: number of bytes to allocate
76 * @count: number of elements in array
78 * Resize the block of memory in 'ptrptr' to be an array of
79 * 'count' elements, each 'size' bytes in length. Update 'ptrptr'
80 * with the address of the newly allocated memory. On failure,
81 * 'ptrptr' is not changed and still points to the original memory
82 * block. The newly allocated memory is filled with zeros.
84 * Returns -1 on failure to allocate, zero on success
86 int mem_realloc_n(void *ptrptr, size_t size, size_t count)
89 if (size == 0 || count == 0) {
90 free(*(void **)ptrptr);
91 *(void **)ptrptr = NULL;
94 if (xalloc_oversized(count, size)) {
98 tmp = realloc(*(void**)ptrptr, size * count);
101 *(void**)ptrptr = tmp;