MSWindowsScreenSaver.cpp

/*
 * barrier -- mouse and keyboard sharing utility
 * Copyright (C) 2012-2016 Symless Ltd.
 * Copyright (C) 2002 Chris Schoeneman
 *
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file LICENSE that should have accompanied this file.
 *
 * This package is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "platform/MSWindowsScreenSaver.h"

#include "platform/MSWindowsScreen.h"
#include "mt/Thread.h"
#include "arch/Arch.h"
#include "arch/win32/ArchMiscWindows.h"
#include "base/Log.h"

#include <malloc.h>
#include <tchar.h>

#if !defined(SPI_GETSCREENSAVERRUNNING)
#define SPI_GETSCREENSAVERRUNNING 114
#endif

static const TCHAR* g_isSecureNT = "ScreenSaverIsSecure";
static const TCHAR* g_isSecure9x = "ScreenSaveUsePassword";
static const TCHAR* const g_pathScreenSaverIsSecure[] = {
    "Control Panel",
    "Desktop",
    NULL
};

//
// MSWindowsScreenSaver
//

MSWindowsScreenSaver::MSWindowsScreenSaver() :
    m_wasSecure(false),
    m_wasSecureAnInt(false),
    m_process(NULL),
    m_watch(NULL),
    m_threadID(0),
    m_msg(0),
    m_wParam(0),
    m_lParam(0),
    m_active(false)
{
    // check if screen saver is enabled
    SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0, &m_wasEnabled, 0);
}

MSWindowsScreenSaver::~MSWindowsScreenSaver()
{
    unwatchProcess();
}

bool
MSWindowsScreenSaver::checkStarted(UINT msg, WPARAM wParam, LPARAM lParam)
{
    // if already started then say it didn't just start
    if (m_active) {
        return false;
    }

    // screen saver may have started.  look for it and get
    // the process.  if we can't find it then assume it
    // didn't really start.  we wait a moment before
    // looking to give the screen saver a chance to start.
    // this shouldn't be a problem since we only get here
    // if the screen saver wants to kick in, meaning that
    // the system is idle or the user deliberately started
    // the screen saver.
    Sleep(250);

    // set parameters common to all screen saver handling
    m_threadID = GetCurrentThreadId();
    m_msg      = msg;
    m_wParam   = wParam;
    m_lParam   = lParam;

    // on the windows nt family we wait for the desktop to
    // change until it's neither the Screen-Saver desktop
    // nor a desktop we can't open (the login desktop).
    // since windows will send the request-to-start-screen-
    // saver message even when the screen saver is disabled
    // we first check that the screen saver is indeed active
    // before watching for it to stop.
    if (!isActive()) {
        LOG((CLOG_DEBUG2 "can't open screen saver desktop"));
        return false;
    }

    watchDesktop();
    return true;
}

void
MSWindowsScreenSaver::enable()
{
    SystemParametersInfo(SPI_SETSCREENSAVEACTIVE, m_wasEnabled, 0, 0);

    // restore password protection
    if (m_wasSecure) {
        setSecure(true, m_wasSecureAnInt);
    }

    // restore display power down
    ArchMiscWindows::removeBusyState(ArchMiscWindows::kDISPLAY);
}

void
MSWindowsScreenSaver::disable()
{
    SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0, &m_wasEnabled, 0);
    SystemParametersInfo(SPI_SETSCREENSAVEACTIVE, FALSE, 0, 0);

    // disable password protected screensaver
    m_wasSecure = isSecure(&m_wasSecureAnInt);
    if (m_wasSecure) {
        setSecure(false, m_wasSecureAnInt);
    }

    // disable display power down
    ArchMiscWindows::addBusyState(ArchMiscWindows::kDISPLAY);
}

void
MSWindowsScreenSaver::activate()
{
    // don't activate if already active
    if (!isActive()) {
        // activate
        HWND hwnd = GetForegroundWindow();
        if (hwnd != NULL) {
            PostMessage(hwnd, WM_SYSCOMMAND, SC_SCREENSAVE, 0);
        }
        else {
            // no foreground window.  pretend we got the event instead.
            DefWindowProc(NULL, WM_SYSCOMMAND, SC_SCREENSAVE, 0);
        }

        // restore power save when screen saver activates
        ArchMiscWindows::removeBusyState(ArchMiscWindows::kDISPLAY);
    }
}

void
MSWindowsScreenSaver::deactivate()
{
    bool killed = false;

    // NT runs screen saver in another desktop
    HDESK desktop = OpenDesktop("Screen-saver", 0, FALSE,
                            DESKTOP_READOBJECTS | DESKTOP_WRITEOBJECTS);
    if (desktop != NULL) {
        EnumDesktopWindows(desktop,
                            &MSWindowsScreenSaver::killScreenSaverFunc,
                            reinterpret_cast<LPARAM>(&killed));
        CloseDesktop(desktop);
    }

    // if above failed or wasn't tried, try the windows 95 way
    if (!killed) {
        // find screen saver window and close it
        HWND hwnd = FindWindow("WindowsScreenSaverClass", NULL);
        if (hwnd == NULL) {
            // win2k may use a different class
            hwnd = FindWindow("Default Screen Saver", NULL);
        }
        if (hwnd != NULL) {
            PostMessage(hwnd, WM_CLOSE, 0, 0);
        }
    }

    // force timer to restart
    SystemParametersInfo(SPI_GETSCREENSAVEACTIVE, 0, &m_wasEnabled, 0);
    SystemParametersInfo(SPI_SETSCREENSAVEACTIVE,
                                !m_wasEnabled, 0, SPIF_SENDWININICHANGE);
    SystemParametersInfo(SPI_SETSCREENSAVEACTIVE,
                                 m_wasEnabled, 0, SPIF_SENDWININICHANGE);

    // disable display power down
    ArchMiscWindows::removeBusyState(ArchMiscWindows::kDISPLAY);
}

bool
MSWindowsScreenSaver::isActive() const
{
    BOOL running;
    SystemParametersInfo(SPI_GETSCREENSAVERRUNNING, 0, &running, 0);
    return (running != FALSE);
}

BOOL CALLBACK
MSWindowsScreenSaver::killScreenSaverFunc(HWND hwnd, LPARAM arg)
{
    if (IsWindowVisible(hwnd)) {
        HINSTANCE instance = (HINSTANCE)GetWindowLongPtr(hwnd, GWLP_HINSTANCE);
        if (instance != MSWindowsScreen::getWindowInstance()) {
            PostMessage(hwnd, WM_CLOSE, 0, 0);
            *reinterpret_cast<bool*>(arg) = true;
        }
    }
    return TRUE;
}

void
MSWindowsScreenSaver::watchDesktop()
{
    // stop watching previous process/desktop
    unwatchProcess();

    // watch desktop in another thread
    LOG((CLOG_DEBUG "watching screen saver desktop"));
    m_active = true;
    m_watch  = new Thread([this](){ watch_desktop_thread(); });
}

void
MSWindowsScreenSaver::watchProcess(HANDLE process)
{
    // stop watching previous process/desktop
    unwatchProcess();

    // watch new process in another thread
    if (process != NULL) {
        LOG((CLOG_DEBUG "watching screen saver process"));
        m_process = process;
        m_active  = true;
        m_watch   = new Thread([this](){ watch_process_thread(); });
    }
}

void
MSWindowsScreenSaver::unwatchProcess()
{
    if (m_watch != NULL) {
        LOG((CLOG_DEBUG "stopped watching screen saver process/desktop"));
        m_watch->cancel();
        m_watch->wait();
        delete m_watch;
        m_watch  = NULL;
        m_active = false;
    }
    if (m_process != NULL) {
        CloseHandle(m_process);
        m_process = NULL;
    }
}

void MSWindowsScreenSaver::watch_desktop_thread()
{
    DWORD reserved = 0;
    TCHAR* name    = NULL;

    for (;;) {
        // wait a bit
        ARCH->sleep(0.2);

        BOOL running;
        SystemParametersInfo(SPI_GETSCREENSAVERRUNNING, 0, &running, 0);
        if (running) {
            continue;
        }

        // send screen saver deactivation message
        m_active = false;
        PostThreadMessage(m_threadID, m_msg, m_wParam, m_lParam);
        return;
    }
}

void MSWindowsScreenSaver::watch_process_thread()
{
    for (;;) {
        Thread::testCancel();
        if (WaitForSingleObject(m_process, 50) == WAIT_OBJECT_0) {
            // process terminated
            LOG((CLOG_DEBUG "screen saver died"));

            // send screen saver deactivation message
            m_active = false;
            PostThreadMessage(m_threadID, m_msg, m_wParam, m_lParam);
            return;
        }
    }
}

void
MSWindowsScreenSaver::setSecure(bool secure, bool saveSecureAsInt)
{
    HKEY hkey =
        ArchMiscWindows::addKey(HKEY_CURRENT_USER, g_pathScreenSaverIsSecure);
    if (hkey == NULL) {
        return;
    }

    if (saveSecureAsInt) {
        ArchMiscWindows::setValue(hkey, g_isSecureNT, secure ? 1 : 0);
    }
    else {
        ArchMiscWindows::setValue(hkey, g_isSecureNT, secure ? "1" : "0");
    }

    ArchMiscWindows::closeKey(hkey);
}

bool
MSWindowsScreenSaver::isSecure(bool* wasSecureFlagAnInt) const
{
    // get the password protection setting key
    HKEY hkey =
        ArchMiscWindows::openKey(HKEY_CURRENT_USER, g_pathScreenSaverIsSecure);
    if (hkey == NULL) {
        return false;
    }

    // get the value.  the value may be an int or a string, depending
    // on the version of windows.
    bool result;
    switch (ArchMiscWindows::typeOfValue(hkey, g_isSecureNT)) {
    default:
        result = false;
        break;

    case ArchMiscWindows::kUINT: {
        DWORD value =
            ArchMiscWindows::readValueInt(hkey, g_isSecureNT);
        *wasSecureFlagAnInt = true;
        result = (value != 0);
        break;
    }

    case ArchMiscWindows::kSTRING: {
        std::string value =
            ArchMiscWindows::readValueString(hkey, g_isSecureNT);
        *wasSecureFlagAnInt = false;
        result = (value != "0");
        break;
    }
    }

    ArchMiscWindows::closeKey(hkey);
    return result;
}