2 * safe-alloc.c: safer memory allocation
4 * Copyright (C) 2009 Free Software Foundation, Inc.
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
22 /* Written by Daniel Berrange <berrange@redhat.com>, 2008 */
30 #include "safe-alloc.h"
33 /* Return 1 if an array of N objects, each of size S, cannot exist due
34 to size arithmetic overflow. S must be positive and N must be
35 nonnegative. This is a macro, not an inline function, so that it
36 works correctly even when SIZE_MAX < N.
38 By gnulib convention, SIZE_MAX represents overflow in size
39 calculations, so the conservative dividend to use here is
40 SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
41 However, malloc (SIZE_MAX) fails on all known hosts where
42 sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
43 exactly-SIZE_MAX allocations on such hosts; this avoids a test and
44 branch when S is known to be 1.
46 This is the same as xalloc_oversized from xalloc.h
48 #define safe_alloc_oversized(n, s) \
49 ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
54 * @ptrptr: pointer to pointer for address of allocated memory
55 * @size: number of bytes to allocate
56 * @count: number of elements to allocate
58 * Allocate an array of memory 'count' elements long,
59 * each with 'size' bytes. Return the address of the
60 * allocated memory in 'ptrptr'. The newly allocated
61 * memory is filled with zeros.
63 * Return -1 on failure to allocate, zero on success
66 safe_alloc_alloc_n (void *ptrptr, size_t size, size_t count, int zeroed)
68 if (size == 0 || count == 0)
70 *(void **) ptrptr = NULL;
74 if (safe_alloc_oversized (count, size))
81 *(void **) ptrptr = calloc (count, size);
83 *(void **) ptrptr = malloc (count * size);
85 if (*(void **) ptrptr == NULL)
91 * safe_alloc_realloc_n:
92 * @ptrptr: pointer to pointer for address of allocated memory
93 * @size: number of bytes to allocate
94 * @count: number of elements in array
96 * Resize the block of memory in 'ptrptr' to be an array of
97 * 'count' elements, each 'size' bytes in length. Update 'ptrptr'
98 * with the address of the newly allocated memory. On failure,
99 * 'ptrptr' is not changed and still points to the original memory
100 * block. The newly allocated memory is filled with zeros.
102 * Return -1 on failure to allocate, zero on success
105 safe_alloc_realloc_n (void *ptrptr, size_t size, size_t count)
108 if (size == 0 || count == 0)
110 free (*(void **) ptrptr);
111 *(void **) ptrptr = NULL;
114 if (safe_alloc_oversized (count, size))
119 tmp = realloc (*(void **) ptrptr, size * count);
122 *(void **) ptrptr = tmp;