charconv/fuzzing/fuzz_to_chars_float.cpp

// Copyright 2024 Matt Borland
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt

#include <boost/charconv.hpp>
#include <boost/core/detail/string_view.hpp>
#include <iostream>
#include <exception>

extern "C" int LLVMFuzzerTestOneInput(const std::uint8_t* data, std::size_t size)
{
    try
    {
        auto c_data = reinterpret_cast<const char*>(data);

        const auto formats = {boost::charconv::chars_format::general,
                                                   boost::charconv::chars_format::fixed,
                                                   boost::charconv::chars_format::scientific,
                                                   boost::charconv::chars_format::hex};

        for (const auto format : formats)
        {
            char buffer[20]; // Small enough it should encounter overflows

            float f_val {};
            boost::charconv::from_chars(c_data, c_data + size, f_val, format);
            boost::charconv::to_chars(buffer, buffer + sizeof(buffer), f_val, format);

            double val {};
            boost::charconv::from_chars(c_data, c_data + size, val, format);
            boost::charconv::to_chars(buffer, buffer + sizeof(buffer), val, format);

            #if BOOST_CHARCONV_LDBL_BITS == 64
            long double ld_val {};
            boost::charconv::from_chars(c_data, c_data + size, ld_val, format);
            boost::charconv::to_chars(buffer, buffer + sizeof(buffer), ld_val, format);
            #endif

            // Also try with precisions
            for (int precision = -1; precision < 10; ++precision)
            {
                boost::charconv::to_chars(buffer, buffer + sizeof(buffer), f_val, format, precision);
                boost::charconv::to_chars(buffer, buffer + sizeof(buffer), val, format, precision);
                #if BOOST_CHARCONV_LDBL_BITS == 64
                boost::charconv::to_chars(buffer, buffer + sizeof(buffer), ld_val, format, precision);
                #endif
            }
        }
    }
    catch(...)
    {
        std::cerr << "Error with: " << data << std::endl;
        std::terminate();
    }

    return 0;
}