4jcraft/Minecraft.World/Util/PortableFileIO.h

#pragma once

#include <cstddef>
#include <cstdio>
#include <string>

#include "StringHelpers.h"

namespace PortableFileIO {
enum class BinaryReadStatus {
    ok,
    not_found,
    too_large,
    read_error,
};

struct BinaryReadResult {
    BinaryReadStatus status;
    std::size_t bytesRead;
    std::size_t fileSize;
};

inline std::FILE* OpenBinaryFileForRead(const std::wstring& path) {
#if defined(_WIN32)
    return _wfopen(path.c_str(), L"rb");
#else
    const std::string nativePath = wstringtofilename(path);
    return std::fopen(nativePath.c_str(), "rb");
#endif
}

inline bool Seek(std::FILE* file, std::size_t offset, int origin) {
#if defined(_WIN32)
    return _fseeki64(file, static_cast<int64_t>(offset), origin) == 0;
#else
    return fseeko(file, static_cast<off_t>(offset), origin) == 0;
#endif
}

inline int64_t Tell(std::FILE* file) {
#if defined(_WIN32)
    return _ftelli64(file);
#else
    return static_cast<int64_t>(ftello(file));
#endif
}

inline BinaryReadResult ReadBinaryFile(const std::wstring& path, void* buffer,
                                       std::size_t capacity) {
    std::FILE* stream = OpenBinaryFileForRead(path);
    if (stream == NULL) {
        return {BinaryReadStatus::not_found, 0, 0};
    }

    if (!Seek(stream, 0, SEEK_END)) {
        std::fclose(stream);
        return {BinaryReadStatus::read_error, 0, 0};
    }

    const int64_t endPosition = Tell(stream);
    if (endPosition < 0) {
        std::fclose(stream);
        return {BinaryReadStatus::read_error, 0, 0};
    }

    const std::size_t fileSize = static_cast<std::size_t>(endPosition);
    if (fileSize > capacity) {
        std::fclose(stream);
        return {BinaryReadStatus::too_large, 0, fileSize};
    }

    if (!Seek(stream, 0, SEEK_SET)) {
        std::fclose(stream);
        return {BinaryReadStatus::read_error, 0, fileSize};
    }

    const std::size_t bytesRead = std::fread(buffer, 1, fileSize, stream);
    const bool failed = std::ferror(stream) != 0;
    std::fclose(stream);
    if (failed || bytesRead != fileSize) {
        return {BinaryReadStatus::read_error, bytesRead, fileSize};
    }

    return {BinaryReadStatus::ok, bytesRead, fileSize};
}

inline BinaryReadResult ReadBinaryFileSegment(const std::wstring& path,
                                              std::size_t offset, void* buffer,
                                              std::size_t bytesToRead) {
    std::FILE* stream = OpenBinaryFileForRead(path);
    if (stream == NULL) {
        return {BinaryReadStatus::not_found, 0, 0};
    }

    if (!Seek(stream, 0, SEEK_END)) {
        std::fclose(stream);
        return {BinaryReadStatus::read_error, 0, 0};
    }

    const int64_t endPosition = Tell(stream);
    if (endPosition < 0) {
        std::fclose(stream);
        return {BinaryReadStatus::read_error, 0, 0};
    }

    const std::size_t fileSize = static_cast<std::size_t>(endPosition);
    if ((offset > fileSize) || (bytesToRead > (fileSize - offset))) {
        std::fclose(stream);
        return {BinaryReadStatus::too_large, 0, fileSize};
    }

    if (!Seek(stream, offset, SEEK_SET)) {
        std::fclose(stream);
        return {BinaryReadStatus::read_error, 0, fileSize};
    }

    const std::size_t bytesRead = std::fread(buffer, 1, bytesToRead, stream);
    const bool failed = std::ferror(stream) != 0;
    std::fclose(stream);
    if (failed || bytesRead != bytesToRead) {
        return {BinaryReadStatus::read_error, bytesRead, fileSize};
    }

    return {BinaryReadStatus::ok, bytesRead, fileSize};
}

inline bool WriteBinaryFile(const std::wstring& path, const void* buffer,
                            std::size_t bytesToWrite) {
#if defined(_WIN32)
    std::FILE* stream = _wfopen(path.c_str(), L"wb");
#else
    const std::string nativePath = wstringtofilename(path);
    std::FILE* stream = std::fopen(nativePath.c_str(), "wb");
#endif
    if (stream == NULL) {
        return false;
    }

    const std::size_t bytesWritten =
        std::fwrite(buffer, 1, bytesToWrite, stream);
    const bool failed =
        std::ferror(stream) != 0 || bytesWritten != bytesToWrite;
    const bool closeFailed = std::fclose(stream) != 0;
    return !failed && !closeFailed;
}
}  // namespace PortableFileIO