system.hpp

/*
    SPDX-License-Identifier: MIT
    Copyright © 2023 Amebis
*/
 
#pragma once
 
#ifdef _WIN32
#define NOMINMAX // Collides with std::min/max
#include <windows.h>
#include <intsafe.h>
#include <tchar.h>
#else
#include <unistd.h>
#endif
#include "sal.hpp"
#include <assert.h>
#include <stdexcept>
 
// In case somebody #included <windows.h> before us and didn't #define NOMINMAX
#ifdef _WIN32
#ifdef min
#undef min
#endif
#ifdef max
#undef max
#endif
#endif
 
namespace stdex
{
#if defined(_WIN32)
    using sys_handle = HANDLE;
    const sys_handle invalid_handle = INVALID_HANDLE_VALUE;
#else
    using sys_handle = int;
    const sys_handle invalid_handle = (sys_handle)-1;
#endif
 
#if defined(_WIN32)
    using sys_char = TCHAR;
#else
    using sys_char = char;
#define _T(x) x
#endif
 
    class sys_object
    {
    public:
        sys_object(_In_opt_ sys_handle h = invalid_handle) : m_h(h) {}
 
        sys_object(_In_ const sys_object& other) : m_h(other.m_h != invalid_handle ? duplicate(other.m_h, false) : invalid_handle) {}
 
        sys_object& operator =(_In_ const sys_object& other)
        {
            if (this != std::addressof(other)) {
                if (m_h != invalid_handle)
                    close(m_h);
                m_h = other.m_h != invalid_handle ? duplicate(other.m_h, false) : invalid_handle;
            }
            return *this;
        }
 
        sys_object(_Inout_ sys_object&& other) noexcept : m_h(other.m_h)
        {
            other.m_h = invalid_handle;
        }
 
        sys_object& operator =(_Inout_ sys_object&& other) noexcept
        {
            if (this != std::addressof(other)) {
                if (m_h != invalid_handle)
                    close(m_h);
                m_h = other.m_h;
                other.m_h = invalid_handle;
            }
            return *this;
        }
 
        virtual ~sys_object()
        {
            if (m_h != invalid_handle)
                close(m_h);
        }
 
        virtual void close()
        {
            if (m_h != invalid_handle) {
                close(m_h);
                m_h = invalid_handle;
            }
        }
 
        inline operator bool() const noexcept { return m_h != invalid_handle; }
 
        inline sys_handle get() const noexcept { return m_h; }
 
    protected:
        static void close(sys_handle h)
        {
#ifdef _WIN32
            if (CloseHandle(h) || GetLastError() == ERROR_INVALID_HANDLE)
#else
            if (close(h) >= 0 || errno == EBADF)
#endif
                return;
            throw std::runtime_error("failed to close handle");
        }
 
        static sys_handle duplicate(_In_ sys_handle h, _In_ bool inherit)
        {
            sys_handle h_new;
#ifdef _WIN32
            HANDLE process = GetCurrentProcess();
            if (DuplicateHandle(process, h, process, &h_new, 0, inherit, DUPLICATE_SAME_ACCESS))
#else
            UNREFERENCED_PARAMETER(inherit);
            if ((h_new = dup(h)) >= 0)
#endif
                return h_new;
            throw std::runtime_error("failed to duplicate handle");
        }
 
    protected:
        sys_handle m_h;
    };
 
#ifdef _WIN32
    template <class T>
    class safearray_accessor
    {
    public:
        safearray_accessor(_In_ LPSAFEARRAY sa) : m_sa(sa)
        {
            HRESULT hr = SafeArrayAccessData(sa, reinterpret_cast<void HUGEP**>(&m_data));
            if (FAILED(hr))
                throw std::invalid_argument("SafeArrayAccessData failed");
        }
 
        ~safearray_accessor()
        {
            SafeArrayUnaccessData(m_sa);
        }
 
        T* data() const { return m_data; }
 
    protected:
        LPSAFEARRAY m_sa;
        T* m_data;
    };
 
    struct SafeArrayDestroy_delete
    {
        void operator()(_In_ LPSAFEARRAY sa) const
        {
            SafeArrayDestroy(sa);
        }
    };
 
    struct SysFreeString_delete
    {
        void operator()(_In_ BSTR sa) const
        {
            SysFreeString(sa);
        }
    };
#endif
}