um/libservice/src/windows_error.cpp


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// Copyright (c) 2015 Egor Tensin <Egor.Tensin@gmail.com>
// This file is part of the "Windows 7 drivers" project.
// For details, see https://github.com/egor-tensin/windows7-drivers.
// Distributed under the MIT License.

#include "libservice/all.hpp"

#include <Windows.h>

#include <string>

namespace libservice
{
    std::string WindowsErrorCategory::message(int code) const
    {
        char* buf_ptr;

        const auto nbwritten = FormatMessageA(
            FORMAT_MESSAGE_ALLOCATE_BUFFER
                | FORMAT_MESSAGE_FROM_SYSTEM
                | FORMAT_MESSAGE_IGNORE_INSERTS,
            NULL,
            code,
            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
            reinterpret_cast<char*>(&buf_ptr),
            0,
            NULL);

        if (0 == nbwritten)
        {
            LocalFree(buf_ptr);
            return "Couldn't format error message";
        }

        std::string str(buf_ptr, nbwritten - 2);
        LocalFree(buf_ptr);
        return str;
    }
}