1 /*
2 * Copyright (c) 2014-2020 Pavel Kalvoda <me@pavelkalvoda.com>
3 *
4 * libcbor is free software; you can redistribute it and/or modify
5 * it under the terms of the MIT license. See LICENSE for details.
6 */
7
8 #include "memory_utils.h"
9 #include "cbor/common.h"
10
11 // TODO: Consider builtins
12 // (https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html)
13
14 /** Highest on bit position */
_cbor_highest_bit(size_t number)15 size_t _cbor_highest_bit(size_t number) {
16 size_t bit = 0;
17 while (number != 0) {
18 bit++;
19 number >>= 1;
20 }
21
22 return bit;
23 }
24
_cbor_safe_to_multiply(size_t a,size_t b)25 bool _cbor_safe_to_multiply(size_t a, size_t b) {
26 if (a <= 1 || b <= 1) return true;
27 return _cbor_highest_bit(a) + _cbor_highest_bit(b) <= sizeof(size_t) * 8;
28 }
29
_cbor_safe_to_add(size_t a,size_t b)30 bool _cbor_safe_to_add(size_t a, size_t b) {
31 // Unsigned integer overflow doesn't constitute UB
32 size_t sum = a + b;
33 return sum >= a && sum >= b;
34 }
35
_cbor_safe_signaling_add(size_t a,size_t b)36 size_t _cbor_safe_signaling_add(size_t a, size_t b) {
37 if (a == 0 || b == 0) return 0;
38 if (_cbor_safe_to_add(a, b)) return a + b;
39 return 0;
40 }
41
_cbor_alloc_multiple(size_t item_size,size_t item_count)42 void* _cbor_alloc_multiple(size_t item_size, size_t item_count) {
43 if (_cbor_safe_to_multiply(item_size, item_count)) {
44 return _cbor_malloc(item_size * item_count);
45 } else {
46 return NULL;
47 }
48 }
49
_cbor_realloc_multiple(void * pointer,size_t item_size,size_t item_count)50 void* _cbor_realloc_multiple(void* pointer, size_t item_size,
51 size_t item_count) {
52 if (_cbor_safe_to_multiply(item_size, item_count)) {
53 return _cbor_realloc(pointer, item_size * item_count);
54 } else {
55 return NULL;
56 }
57 }
58