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/*
* Copyright (c) 2014-2020 Pavel Kalvoda <me@pavelkalvoda.com>
*
* libcbor is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See LICENSE for details.
*/
#include "memory_utils.h"
#include "cbor/common.h"
// TODO: Consider builtins
// (https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html)
/** Highest on bit position */
size_t _cbor_highest_bit(size_t number) {
size_t bit = 0;
while (number != 0) {
bit++;
number >>= 1;
}
return bit;
}
bool _cbor_safe_to_multiply(size_t a, size_t b) {
if (a <= 1 || b <= 1) return true;
return _cbor_highest_bit(a) + _cbor_highest_bit(b) <= sizeof(size_t) * 8;
}
bool _cbor_safe_to_add(size_t a, size_t b) {
// Unsigned integer overflow doesn't constitute UB
size_t sum = a + b;
return sum >= a && sum >= b;
}
size_t _cbor_safe_signaling_add(size_t a, size_t b) {
if (a == 0 || b == 0) return 0;
if (_cbor_safe_to_add(a, b)) return a + b;
return 0;
}
void* _cbor_alloc_multiple(size_t item_size, size_t item_count) {
if (_cbor_safe_to_multiply(item_size, item_count)) {
return _cbor_malloc(item_size * item_count);
} else {
return NULL;
}
}
void* _cbor_realloc_multiple(void* pointer, size_t item_size,
size_t item_count) {
if (_cbor_safe_to_multiply(item_size, item_count)) {
return _cbor_realloc(pointer, item_size * item_count);
} else {
return NULL;
}
}
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