system.hpp

/*
    SPDX-License-Identifier: MIT
    Copyright © 2023 Amebis
*/
 
#pragma once
 
#include "compat.hpp"
#ifdef _WIN32
#include <windows.h>
#include <oaidl.h>
#include <tchar.h>
#else
#define _LARGEFILE64_SOURCE
#include <grp.h>
#include <pwd.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#endif
#include <regex>
#include <stdexcept>
#include <string>
 
#if defined(_WIN32)
#define PATH_SEPARATOR '\\'
#define PATH_SEPARATOR_STR "\\"
#else
#define PATH_SEPARATOR '/'
#define PATH_SEPARATOR_STR "/"
#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)
    inline DWORD sys_error() { return GetLastError(); }
#else
    inline int sys_error() { return errno; }
#endif
 
#if defined(_WIN32)
    using schar_t = TCHAR;
#else
    using schar_t = char;
#define _T(x) x
#endif
 
    using sys_char = schar_t;
 
    using sstring = std::basic_string<stdex::schar_t>;
 
    using sys_string = sstring;
 
    using sregex = std::basic_regex<stdex::schar_t>;
 
    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() noexcept(false)
        {
            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(_In_ sys_handle h)
        {
#ifdef _WIN32
            if (CloseHandle(h) || GetLastError() == ERROR_INVALID_HANDLE)
                return;
            throw std::system_error(GetLastError(), std::system_category(), "CloseHandle failed");
#else
            if (::close(h) >= 0 || errno == EBADF)
                return;
            throw std::system_error(errno, std::system_category(), "close failed");
#endif
        }
 
        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))
                return h_new;
            throw std::system_error(GetLastError(), std::system_category(), "DuplicateHandle failed");
#else
            _Unreferenced_(inherit);
            if ((h_new = dup(h)) >= 0)
                return h_new;
            throw std::system_error(errno, std::system_category(), "dup failed");
#endif
        }
 
    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::system_error(hr, std::system_category(), "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
 
#ifdef _WIN32
    typedef uint16_t platform_id;
#else
    typedef const char* platform_id;
 
    inline bool operator ==(_In_ const platform_id a, _In_ const platform_id b) { return a == b; }
    inline bool operator !=(_In_ const platform_id a, _In_ const platform_id b) { return a != b; }
    inline bool operator <(_In_ const platform_id a, _In_ const platform_id b) { return a == IMAGE_FILE_MACHINE_UNKNOWN && b != IMAGE_FILE_MACHINE_UNKNOWN || a != IMAGE_FILE_MACHINE_UNKNOWN && b != IMAGE_FILE_MACHINE_UNKNOWN && strcmp(a, b) < 0; }
    inline bool operator <=(_In_ const platform_id a, _In_ const platform_id b) { return a == IMAGE_FILE_MACHINE_UNKNOWN || a != IMAGE_FILE_MACHINE_UNKNOWN && b != IMAGE_FILE_MACHINE_UNKNOWN && strcmp(a, b) <= 0; }
    inline bool operator >(_In_ const platform_id a, _In_ const platform_id b) { return a != IMAGE_FILE_MACHINE_UNKNOWN && b == IMAGE_FILE_MACHINE_UNKNOWN || a != IMAGE_FILE_MACHINE_UNKNOWN && b != IMAGE_FILE_MACHINE_UNKNOWN && strcmp(a, b) > 0; }
    inline bool operator >=(_In_ const platform_id a, _In_ const platform_id b) { return b == IMAGE_FILE_MACHINE_UNKNOWN || a != IMAGE_FILE_MACHINE_UNKNOWN && b != IMAGE_FILE_MACHINE_UNKNOWN && strcmp(a, b) >= 0; }
#endif
}
 
#ifndef _WIN32
constexpr stdex::platform_id IMAGE_FILE_MACHINE_UNKNOWN = nullptr;
constexpr stdex::platform_id IMAGE_FILE_MACHINE_I386 = "i386";
constexpr stdex::platform_id IMAGE_FILE_MACHINE_AMD64 = "x86_64";
constexpr stdex::platform_id IMAGE_FILE_MACHINE_ARMNT = "arm";
constexpr stdex::platform_id IMAGE_FILE_MACHINE_ARM64 = "aarch64";
#endif
 
namespace stdex
{
    const struct sys_info_t
    {
#if _M_IX86
        static constexpr platform_id process_platform = IMAGE_FILE_MACHINE_I386;
#elif _M_X64 // _M_ARM64EC is introducing as x64
        static constexpr platform_id process_platform = IMAGE_FILE_MACHINE_AMD64;
#elif _M_ARM
        static constexpr platform_id process_platform = IMAGE_FILE_MACHINE_ARMNT;
#elif _M_ARM64
        static constexpr platform_id process_platform = IMAGE_FILE_MACHINE_ARM64;
#elif __i386__
        static constexpr platform_id process_platform = "i386";
#elif __x86_64__
        static constexpr platform_id process_platform = "x86_64";
#elif __aarch64__
        static constexpr platform_id process_platform = "aarch64";
#else
        #error Unknown platform
#endif
 
        platform_id os_platform;
 
#ifdef _WIN32
        bool wow64;
#endif
 
        bool interactive_process;
 
        bool admin;
 
        bool elevated;
 
        sys_info_t() :
            os_platform(IMAGE_FILE_MACHINE_UNKNOWN),
            wow64(false),
            interactive_process(true),
            admin(false),
            elevated(false)
        {
#ifdef _WIN32
            HMODULE kernel32_handle;
            kernel32_handle = LoadLibrary(_T("kernel32.dll"));
            _Assume_(kernel32_handle);
            BOOL(WINAPI * IsWow64Process2)(HANDLE hProcess, USHORT * pProcessMachine, USHORT * pNativeMachine);
            *reinterpret_cast<FARPROC*>(&IsWow64Process2) = GetProcAddress(kernel32_handle, "IsWow64Process2");
            HANDLE process = GetCurrentProcess();
            USHORT process_machine;
#ifndef _WIN64
            BOOL Wow64Process;
#endif
            if (IsWow64Process2 && IsWow64Process2(process, &process_machine, &os_platform)) {
                wow64 = process_machine != IMAGE_FILE_MACHINE_UNKNOWN;
            }
#ifdef _WIN64
            else {
                os_platform = process_platform;
                wow64 = false;
            }
#else
            else if (IsWow64Process(process, &Wow64Process)) {
                if (Wow64Process) {
                    os_platform = IMAGE_FILE_MACHINE_AMD64;
                    wow64 = true;
                }
                else {
                    os_platform = process_platform;
                    wow64 = false;
                }
            }
#endif
            FreeLibrary(kernel32_handle);
#else
            memset(&m_utsn, 0, sizeof(m_utsn));
            if (uname(&m_utsn) != -1)
                os_platform = reinterpret_cast<platform_id>(m_utsn.machine);
#endif
 
#ifdef _WIN32
            HWINSTA hWinSta = GetProcessWindowStation();
            if (hWinSta) {
                TCHAR sName[MAX_PATH];
                if (GetUserObjectInformation(hWinSta, UOI_NAME, sName, sizeof(sName), NULL)) {
                    sName[_countof(sName) - 1] = 0;
                    // Only "WinSta0" is interactive (Source: KB171890)
                    interactive_process = _tcsicmp(sName, _T("WinSta0")) == 0;
                }
            }
#else
            // TODO: Research interactive process vs service/agent/daemon on this platform.
#endif
 
#if defined(_WIN32)
            {
                HANDLE token_h;
                if (OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &token_h)) {
                    sys_object token(token_h);
 
                    TOKEN_ELEVATION elevation;
                    DWORD size = sizeof(TOKEN_ELEVATION);
                    if (GetTokenInformation(token_h, TokenElevation, &elevation, sizeof(elevation), &size))
                        elevated = elevation.TokenIsElevated;
 
                    GetTokenInformation(token.get(), TokenGroups, NULL, 0, &size);
                    std::unique_ptr<TOKEN_GROUPS> groups((TOKEN_GROUPS*)new uint8_t[size]);
                    if (GetTokenInformation(token.get(), TokenGroups, (LPVOID)groups.get(), size, &size)) {
                        SID_IDENTIFIER_AUTHORITY authority = SECURITY_NT_AUTHORITY;
                        PSID sid_admins_h = NULL;
                        if (AllocateAndInitializeSid(&authority, 2, SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS, 0, 0, 0, 0, 0, 0, &sid_admins_h)) {
                            struct SID_delete { void operator()(_In_ PSID p) const { FreeSid(p); } };
                            std::unique_ptr<void, SID_delete> sid_admins(sid_admins_h);
                            for (DWORD i = 0; i < groups->GroupCount; ++i)
                                if (EqualSid(sid_admins.get(), groups->Groups[i].Sid)) {
                                    admin = true;
                                    break;
                                }
                        }
                    }
                }
            }
#elif defined(__APPLE__)
            {
                gid_t gids[NGROUPS + 1]; // A user cannot be member in more than NGROUPS groups, not counting the default group (hence the + 1)
                for (int i = 0, n = getgroups(_countof(gids), gids); i < n; ++i) {
                    struct group* group = getgrgid(gids[i]);
                    if (!group) continue;
                    if (strcmp(group->gr_name, "admin") == 0) {
                        admin = true;
                        break;
                    }
                }
            }
 
            elevated = geteuid() == 0;
#else
            // TODO: Set admin.
            elevated = geteuid() == 0;
#endif
        }
 
    protected:
#ifndef _WIN32
        struct utsname m_utsn;
#endif
    } sys_info;
}