memory_utils.c

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/*
 * Copyright (c) 2014-2017 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)

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)
{
    return _cbor_highest_bit(a) + _cbor_highest_bit(b) <= sizeof(size_t) * 8;
}

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;
    }
}