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 */
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 
25 bool _cbor_safe_to_multiply(size_t a, size_t b) {
26   return _cbor_highest_bit(a) + _cbor_highest_bit(b) <= sizeof(size_t) * 8;
27 }
28 
29 void* _cbor_alloc_multiple(size_t item_size, size_t item_count) {
30   if (_cbor_safe_to_multiply(item_size, item_count)) {
31     return _CBOR_MALLOC(item_size * item_count);
32   } else {
33     return NULL;
34   }
35 }
36 
37 void* _cbor_realloc_multiple(void* pointer, size_t item_size,
38                              size_t item_count) {
39   if (_cbor_safe_to_multiply(item_size, item_count)) {
40     return _CBOR_REALLOC(pointer, item_size * item_count);
41   } else {
42     return NULL;
43   }
44 }
45