fuzz coverage

// Copyright (c) 2015-2022 The Bitcoin Core developers

// Copyright (c) 2017 The Zcash developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <util/readwritefile.h>

#include <util/fs.h>

#include <algorithm>

#include <cstdio>

#include <limits>

#include <string>

#include <utility>

std::pair<bool,std::string> ReadBinaryFile(const fs::path &filename, size_t maxsize)

{

    FILE *f = fsbridge::fopen(filename, "rb");

    if (f == nullptr)

        return std::make_pair(false,"");

    std::string retval;

    char buffer[128];

    do {

        const size_t n = fread(buffer, 1, std::min(sizeof(buffer), maxsize - retval.size()), f);

        // Check for reading errors so we don't return any data if we couldn't

        // read the entire file (or up to maxsize)

        if (ferror(f)) {

            fclose(f);

            return std::make_pair(false,"");

        }

        retval.append(buffer, buffer+n);

    } while (!feof(f) && retval.size() < maxsize);

    fclose(f);

    return std::make_pair(true,retval);

}

bool WriteBinaryFile(const fs::path &filename, const std::string &data)

{

    FILE *f = fsbridge::fopen(filename, "wb");

    if (f == nullptr)

        return false;

    if (fwrite(data.data(), 1, data.size(), f) != data.size()) {

        fclose(f);

        return false;

    }

    if (fclose(f) != 0) {

        return false;

    }

    return true;

}