CSynergyHook.cpp

/*
 * synergy -- mouse and keyboard sharing utility
 * Copyright (C) 2012 Bolton Software 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 COPYING 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 "CSynergyHook.h"
#include "ProtocolTypes.h"
#include <zmouse.h>
#include <tchar.h>
 
#if _MSC_VER >= 1400
// VS2005 hack - we don't use assert here because we don't want to link with the CRT.
#undef assert
#if _DEBUG
#define assert(_X_) if (!(_X_)) __debugbreak()
#else
#define assert(_X_) __noop()
#endif
// VS2005 is a bit more smart than VC6 and optimize simple copy loop to
// intrinsic memcpy.
#pragma function(memcpy)
#endif

//
// debugging compile flag.  when not zero the server doesn't grab
// the keyboard when the mouse leaves the server screen.  this
// makes it possible to use the debugger (via the keyboard) when
// all user input would normally be caught by the hook procedures.
//
#define NO_GRAB_KEYBOARD 0

//
// debugging compile flag.  when not zero the server will not
// install low level hooks.
//
#define NO_LOWLEVEL_HOOKS 0

//
// extra mouse wheel stuff
//

enum EWheelSupport {
    kWheelNone,
    kWheelOld,
    kWheelWin2000,
    kWheelModern
};

// declare extended mouse hook struct.  useable on win2k
typedef struct tagMOUSEHOOKSTRUCTWin2000 {
    MOUSEHOOKSTRUCT mhs;
    DWORD mouseData;
} MOUSEHOOKSTRUCTWin2000;

#if !defined(SM_MOUSEWHEELPRESENT)
#define SM_MOUSEWHEELPRESENT 75
#endif

// X button stuff
#if !defined(WM_XBUTTONDOWN)
#define WM_XBUTTONDOWN      0x020B
#define WM_XBUTTONUP        0x020C
#define WM_XBUTTONDBLCLK    0x020D
#define WM_NCXBUTTONDOWN    0x00AB
#define WM_NCXBUTTONUP      0x00AC
#define WM_NCXBUTTONDBLCLK  0x00AD
#define MOUSEEVENTF_XDOWN   0x0080
#define MOUSEEVENTF_XUP     0x0100
#define XBUTTON1            0x0001
#define XBUTTON2            0x0002
#endif


//
// globals
//

#if defined(_MSC_VER)
#pragma comment(linker, "-section:shared,rws")
#pragma data_seg("shared")
#endif
// all data in this shared section *must* be initialized

static HINSTANCE        g_hinstance       = NULL;
static DWORD            g_processID       = 0;
static EWheelSupport    g_wheelSupport    = kWheelNone;
static UINT             g_wmMouseWheel    = 0;
static DWORD            g_threadID        = 0;
static HHOOK            g_keyboard        = NULL;
static HHOOK            g_mouse           = NULL;
static HHOOK            g_getMessage      = NULL;
static HHOOK            g_keyboardLL      = NULL;
static HHOOK            g_mouseLL         = NULL;
static bool             g_screenSaver     = false;
static EHookMode        g_mode            = kHOOK_DISABLE;
static UInt32           g_zoneSides       = 0;
static SInt32           g_zoneSize        = 0;
static SInt32           g_xScreen         = 0;
static SInt32           g_yScreen         = 0;
static SInt32           g_wScreen         = 0;
static SInt32           g_hScreen         = 0;
static WPARAM           g_deadVirtKey     = 0;
static WPARAM           g_deadRelease     = 0;
static LPARAM           g_deadLParam      = 0;
static BYTE             g_deadKeyState[256] = { 0 };
static DWORD            g_hookThread      = 0;
static DWORD            g_attachedThread  = 0;
static bool             g_fakeInput       = false;

#if defined(_MSC_VER)
#pragma data_seg()
#endif

// keep linker quiet about floating point stuff.  we don't use any
// floating point operations but our includes may define some
// (unused) floating point values.
#ifndef _DEBUG
extern "C" {
int _fltused=0;
}
#endif


//
// internal functions
//

static
void
detachThread()
{
    if (g_attachedThread != 0 && g_hookThread != g_attachedThread) {
        AttachThreadInput(g_hookThread, g_attachedThread, FALSE);
        g_attachedThread = 0;
    }
}

static
bool
attachThreadToForeground()
{
    // only attach threads if using low level hooks.  a low level hook
    // runs in the thread that installed the hook but we have to make
    // changes that require being attached to the target thread (which
    // should be the foreground window).  a regular hook runs in the
    // thread that just removed the event from its queue so we're
    // already in the right thread.
    if (g_hookThread != 0) {
        HWND window    = GetForegroundWindow();
        if (window == NULL)
            return false;

        DWORD threadID = GetWindowThreadProcessId(window, NULL);
        // skip if no change
        if (g_attachedThread != threadID) {
            // detach from previous thread
            detachThread();

            // attach to new thread
            if (threadID != 0 && threadID != g_hookThread) {
                AttachThreadInput(g_hookThread, threadID, TRUE);
                g_attachedThread = threadID;
            }
            return true;
        }
    }
    return false;
}

#if !NO_GRAB_KEYBOARD
static
WPARAM
makeKeyMsg(UINT virtKey, char c, bool noAltGr)
{
    return MAKEWPARAM(MAKEWORD(virtKey & 0xff, (BYTE)c), noAltGr ? 1 : 0);
}

static
void
keyboardGetState(BYTE keys[256])
{
    // we have to use GetAsyncKeyState() rather than GetKeyState() because
    // we don't pass through most keys so the event synchronous state
    // doesn't get updated.  we do that because certain modifier keys have
    // side effects, like alt and the windows key.
    SHORT key;
    for (int i = 0; i < 256; ++i) {
        key     = GetAsyncKeyState(i);
        keys[i] = (BYTE)((key < 0) ? 0x80u : 0);
    }
    key = GetKeyState(VK_CAPITAL);
    keys[VK_CAPITAL] = (BYTE)(((key < 0) ? 0x80 : 0) | (key & 1));
}

static
bool
doKeyboardHookHandler(WPARAM wParam, LPARAM lParam)
{
    // check for special events indicating if we should start or stop
    // passing events through and not report them to the server.  this
    // is used to allow the server to synthesize events locally but
    // not pick them up as user events.
    if (wParam == SYNERGY_HOOK_FAKE_INPUT_VIRTUAL_KEY &&
        ((lParam >> 16) & 0xffu) == SYNERGY_HOOK_FAKE_INPUT_SCANCODE) {
        // update flag
        g_fakeInput = ((lParam & 0x80000000u) == 0);
        PostThreadMessage(g_threadID, SYNERGY_MSG_DEBUG,
                                0xff000000u | wParam, lParam);

        // discard event
        return true;
    }

    // if we're expecting fake input then just pass the event through
    // and do not forward to the server
    if (g_fakeInput) {
        PostThreadMessage(g_threadID, SYNERGY_MSG_DEBUG,
                                0xfe000000u | wParam, lParam);
        return false;
    }

    // VK_RSHIFT may be sent with an extended scan code but right shift
    // is not an extended key so we reset that bit.
    if (wParam == VK_RSHIFT) {
        lParam &= ~0x01000000u;
    }

    // tell server about event
    PostThreadMessage(g_threadID, SYNERGY_MSG_DEBUG, wParam, lParam);

    // ignore dead key release
    if ((g_deadVirtKey == wParam || g_deadRelease == wParam) &&
        (lParam & 0x80000000u) != 0) {
        g_deadRelease = 0;
        PostThreadMessage(g_threadID, SYNERGY_MSG_DEBUG,
                        wParam | 0x04000000, lParam);
        return false;
    }

    // we need the keyboard state for ToAscii()
    BYTE keys[256];
    keyboardGetState(keys);

    // ToAscii() maps ctrl+letter to the corresponding control code
    // and ctrl+backspace to delete.  we don't want those translations
    // so clear the control modifier state.  however, if we want to
    // simulate AltGr (which is ctrl+alt) then we must not clear it.
    UINT control = keys[VK_CONTROL] | keys[VK_LCONTROL] | keys[VK_RCONTROL];
    UINT menu    = keys[VK_MENU] | keys[VK_LMENU] | keys[VK_RMENU];
    if ((control & 0x80) == 0 || (menu & 0x80) == 0) {
        keys[VK_LCONTROL] = 0;
        keys[VK_RCONTROL] = 0;
        keys[VK_CONTROL]  = 0;
    }
    else {
        keys[VK_LCONTROL] = 0x80;
        keys[VK_RCONTROL] = 0x80;
        keys[VK_CONTROL]  = 0x80;
        keys[VK_LMENU]    = 0x80;
        keys[VK_RMENU]    = 0x80;
        keys[VK_MENU]     = 0x80;
    }

    // ToAscii() needs to know if a menu is active for some reason.
    // we don't know and there doesn't appear to be any way to find
    // out.  so we'll just assume a menu is active if the menu key
    // is down.
    // FIXME -- figure out some way to check if a menu is active
    UINT flags = 0;
    if ((menu & 0x80) != 0)
        flags |= 1;

    // if we're on the server screen then just pass numpad keys with alt
    // key down as-is.  we won't pick up the resulting character but the
    // local app will.  if on a client screen then grab keys as usual;
    // if the client is a windows system it'll synthesize the expected
    // character.  if not then it'll probably just do nothing.
    if (g_mode != kHOOK_RELAY_EVENTS) {
        // we don't use virtual keys because we don't know what the
        // state of the numlock key is.  we'll hard code the scan codes
        // instead.  hopefully this works across all keyboards.
        UINT sc = (lParam & 0x01ff0000u) >> 16;
        if (menu &&
            (sc >= 0x47u && sc <= 0x52u && sc != 0x4au && sc != 0x4eu)) {
            return false;
        }
    }

    WORD c        = 0;

    // map the key event to a character.  we have to put the dead
    // key back first and this has the side effect of removing it.
    if (g_deadVirtKey != 0) {
        if(ToAscii((UINT)g_deadVirtKey, (g_deadLParam & 0x10ff0000u) >> 16,
                    g_deadKeyState, &c, flags) == 2)
        {
            // If ToAscii returned 2, it means that we accidentally removed
            // a double dead key instead of restoring it. Thus, we call
            // ToAscii again with the same parameters to restore the
            // internal dead key state.
            ToAscii((UINT)g_deadVirtKey, (g_deadLParam & 0x10ff0000u) >> 16,
                    g_deadKeyState, &c, flags);
            
            // We need to keep track of this because g_deadVirtKey will be
            // cleared later on; this would cause the dead key release to
            // incorrectly restore the dead key state.
            g_deadRelease = g_deadVirtKey;
        }
    }
    
    UINT scanCode = ((lParam & 0x10ff0000u) >> 16);
    int n         = ToAscii((UINT)wParam, scanCode, keys, &c, flags);

    // if mapping failed and ctrl and alt are pressed then try again
    // with both not pressed.  this handles the case where ctrl and
    // alt are being used as individual modifiers rather than AltGr.
    // we note that's the case in the message sent back to synergy
    // because there's no simple way to deduce it after the fact.
    // we have to put the dead key back first, if there was one.
    bool noAltGr = false;
    if (n == 0 && (control & 0x80) != 0 && (menu & 0x80) != 0) {
        noAltGr = true;
        PostThreadMessage(g_threadID, SYNERGY_MSG_DEBUG,
                            wParam | 0x05000000, lParam);
        if (g_deadVirtKey != 0) {
            if(ToAscii((UINT)g_deadVirtKey, (g_deadLParam & 0x10ff0000u) >> 16,
                            g_deadKeyState, &c, flags) == 2)
            {
                ToAscii((UINT)g_deadVirtKey, (g_deadLParam & 0x10ff0000u) >> 16,
                            g_deadKeyState, &c, flags);
                g_deadRelease = g_deadVirtKey;
            }
        }
        BYTE keys2[256];
        for (size_t i = 0; i < sizeof(keys) / sizeof(keys[0]); ++i) {
            keys2[i] = keys[i];
        }
        keys2[VK_LCONTROL] = 0;
        keys2[VK_RCONTROL] = 0;
        keys2[VK_CONTROL]  = 0;
        keys2[VK_LMENU]    = 0;
        keys2[VK_RMENU]    = 0;
        keys2[VK_MENU]     = 0;
        n = ToAscii((UINT)wParam, scanCode, keys2, &c, flags);
    }

    PostThreadMessage(g_threadID, SYNERGY_MSG_DEBUG,
                            wParam | ((c & 0xff) << 8) |
                            ((n & 0xff) << 16) | 0x06000000,
                            lParam);
    WPARAM charAndVirtKey = 0;
    bool clearDeadKey = false;
    switch (n) {
    default:
        // key is a dead key

        if(lParam & 0x80000000u)
            // This handles the obscure situation where a key has been
            // pressed which is both a dead key and a normal character
            // depending on which modifiers have been pressed. We
            // break here to prevent it from being considered a dead
            // key.
            break;

        g_deadVirtKey = wParam;
        g_deadLParam  = lParam;
        for (size_t i = 0; i < sizeof(keys) / sizeof(keys[0]); ++i) {
            g_deadKeyState[i] = keys[i];
        }
        break;

    case 0:
        // key doesn't map to a character.  this can happen if
        // non-character keys are pressed after a dead key.
        charAndVirtKey = makeKeyMsg((UINT)wParam, (char)0, noAltGr);
        break;

    case 1:
        // key maps to a character composed with dead key
        charAndVirtKey = makeKeyMsg((UINT)wParam, (char)LOBYTE(c), noAltGr);
        clearDeadKey   = true;
        break;

    case 2: {
        // previous dead key not composed.  send a fake key press
        // and release for the dead key to our window.
        WPARAM deadCharAndVirtKey =
                            makeKeyMsg((UINT)g_deadVirtKey, (char)LOBYTE(c), noAltGr);
        PostThreadMessage(g_threadID, SYNERGY_MSG_KEY,
                            deadCharAndVirtKey, g_deadLParam & 0x7fffffffu);
        PostThreadMessage(g_threadID, SYNERGY_MSG_KEY,
                            deadCharAndVirtKey, g_deadLParam | 0x80000000u);

        // use uncomposed character
        charAndVirtKey = makeKeyMsg((UINT)wParam, (char)HIBYTE(c), noAltGr);
        clearDeadKey   = true;
        break;
    }
    }

    // put back the dead key, if any, for the application to use
    if (g_deadVirtKey != 0) {
        ToAscii((UINT)g_deadVirtKey, (g_deadLParam & 0x10ff0000u) >> 16,
                            g_deadKeyState, &c, flags);
    }

    // clear out old dead key state
    if (clearDeadKey) {
        g_deadVirtKey = 0;
        g_deadLParam  = 0;
    }

    // forward message to our window.  do this whether or not we're
    // forwarding events to clients because this'll keep our thread's
    // key state table up to date.  that's important for querying
    // the scroll lock toggle state.
    // XXX -- with hot keys for actions we may only need to do this when
    // forwarding.
    if (charAndVirtKey != 0) {
        PostThreadMessage(g_threadID, SYNERGY_MSG_DEBUG,
                            charAndVirtKey | 0x07000000, lParam);
        PostThreadMessage(g_threadID, SYNERGY_MSG_KEY, charAndVirtKey, lParam);
    }

    if (g_mode == kHOOK_RELAY_EVENTS) {
        // let certain keys pass through
        switch (wParam) {
        case VK_CAPITAL:
        case VK_NUMLOCK:
        case VK_SCROLL:
            // pass event on.  we want to let these through to
            // the window proc because otherwise the keyboard
            // lights may not stay synchronized.
            break;

        case VK_HANGUL:
            // pass these modifiers if using a low level hook, discard
            // them if not.
            if (g_hookThread == 0) {
                return true;
            }
            break;

        default:
            // discard
            return true;
        }
    }

    return false;
}

static
bool
keyboardHookHandler(WPARAM wParam, LPARAM lParam)
{
    attachThreadToForeground();
    return doKeyboardHookHandler(wParam, lParam);
}
#endif

static
bool
doMouseHookHandler(WPARAM wParam, SInt32 x, SInt32 y, SInt32 data)
{
    switch (wParam) {
    case WM_LBUTTONDOWN:
    case WM_MBUTTONDOWN:
    case WM_RBUTTONDOWN:
    case WM_XBUTTONDOWN:
    case WM_LBUTTONDBLCLK:
    case WM_MBUTTONDBLCLK:
    case WM_RBUTTONDBLCLK:
    case WM_XBUTTONDBLCLK:
    case WM_LBUTTONUP:
    case WM_MBUTTONUP:
    case WM_RBUTTONUP:
    case WM_XBUTTONUP:
    case WM_NCLBUTTONDOWN:
    case WM_NCMBUTTONDOWN:
    case WM_NCRBUTTONDOWN:
    case WM_NCXBUTTONDOWN:
    case WM_NCLBUTTONDBLCLK:
    case WM_NCMBUTTONDBLCLK:
    case WM_NCRBUTTONDBLCLK:
    case WM_NCXBUTTONDBLCLK:
    case WM_NCLBUTTONUP:
    case WM_NCMBUTTONUP:
    case WM_NCRBUTTONUP:
    case WM_NCXBUTTONUP:
        // always relay the event.  eat it if relaying.
        PostThreadMessage(g_threadID, SYNERGY_MSG_MOUSE_BUTTON, wParam, data);
        return (g_mode == kHOOK_RELAY_EVENTS);

    case WM_MOUSEWHEEL:
        if (g_mode == kHOOK_RELAY_EVENTS) {
            // relay event
            PostThreadMessage(g_threadID, SYNERGY_MSG_MOUSE_WHEEL, data, 0);
        }
        return (g_mode == kHOOK_RELAY_EVENTS);

    case WM_NCMOUSEMOVE:
    case WM_MOUSEMOVE:
        if (g_mode == kHOOK_RELAY_EVENTS) {
            // relay and eat event
            PostThreadMessage(g_threadID, SYNERGY_MSG_MOUSE_MOVE, x, y);
            return true;
        }
        else if (g_mode == kHOOK_WATCH_JUMP_ZONE) {
            // low level hooks can report bogus mouse positions that are
            // outside of the screen.  jeez.  naturally we end up getting
            // fake motion in the other direction to get the position back
            // on the screen, which plays havoc with switch on double tap.
            // CServer deals with that.  we'll clamp positions onto the
            // screen.  also, if we discard events for positions outside
            // of the screen then the mouse appears to get a bit jerky
            // near the edge.  we can either accept that or pass the bogus
            // events.  we'll try passing the events.
            bool bogus = false;
            if (x < g_xScreen) {
                x     = g_xScreen;
                bogus = true;
            }
            else if (x >= g_xScreen + g_wScreen) {
                x     = g_xScreen + g_wScreen - 1;
                bogus = true;
            }
            if (y < g_yScreen) {
                y     = g_yScreen;
                bogus = true;
            }
            else if (y >= g_yScreen + g_hScreen) {
                y     = g_yScreen + g_hScreen - 1;
                bogus = true;
            }

            // check for mouse inside jump zone
            bool inside = false;
            if (!inside && (g_zoneSides & kLeftMask) != 0) {
                inside = (x < g_xScreen + g_zoneSize);
            }
            if (!inside && (g_zoneSides & kRightMask) != 0) {
                inside = (x >= g_xScreen + g_wScreen - g_zoneSize);
            }
            if (!inside && (g_zoneSides & kTopMask) != 0) {
                inside = (y < g_yScreen + g_zoneSize);
            }
            if (!inside && (g_zoneSides & kBottomMask) != 0) {
                inside = (y >= g_yScreen + g_hScreen - g_zoneSize);
            }

            // relay the event
            PostThreadMessage(g_threadID, SYNERGY_MSG_MOUSE_MOVE, x, y);

            // if inside and not bogus then eat the event
            return inside && !bogus;
        }
    }

    // pass the event
    return false;
}

static
bool
mouseHookHandler(WPARAM wParam, SInt32 x, SInt32 y, SInt32 data)
{
//  attachThreadToForeground();
    return doMouseHookHandler(wParam, x, y, data);
}

#if !NO_GRAB_KEYBOARD
static
LRESULT CALLBACK
keyboardHook(int code, WPARAM wParam, LPARAM lParam)
{
    if (code >= 0) {
        // handle the message
        if (keyboardHookHandler(wParam, lParam)) {
            return 1;
        }
    }

    return CallNextHookEx(g_keyboard, code, wParam, lParam);
}
#endif

static
LRESULT CALLBACK
mouseHook(int code, WPARAM wParam, LPARAM lParam)
{
    if (code >= 0) {
        // decode message
        const MOUSEHOOKSTRUCT* info = (const MOUSEHOOKSTRUCT*)lParam;
        SInt32 x = (SInt32)info->pt.x;
        SInt32 y = (SInt32)info->pt.y;
        SInt32 w = 0;
        if (wParam == WM_MOUSEWHEEL) {
            // win2k and other systems supporting WM_MOUSEWHEEL in
            // the mouse hook are gratuitously different (and poorly
            // documented).  if a low-level mouse hook is in place
            // it should capture these events so we'll never see
            // them.
            switch (g_wheelSupport) {
            case kWheelModern:
                w = static_cast<SInt16>(LOWORD(info->dwExtraInfo));
                break;

            case kWheelWin2000: {
                const MOUSEHOOKSTRUCTWin2000* info2k =
                        (const MOUSEHOOKSTRUCTWin2000*)lParam;
                w = static_cast<SInt16>(HIWORD(info2k->mouseData));
                break;
            }

            default:
                break;
            }
        }

        // handle the message.  note that we don't handle X buttons
        // here.  that's okay because they're only supported on
        // win2k and winxp and up and on those platforms we'll get
        // get the mouse events through the low level hook.
        if (mouseHookHandler(wParam, x, y, w)) {
            return 1;
        }
    }

    return CallNextHookEx(g_mouse, code, wParam, lParam);
}

static
LRESULT CALLBACK
getMessageHook(int code, WPARAM wParam, LPARAM lParam)
{
    if (code >= 0) {
        if (g_screenSaver) {
            MSG* msg = reinterpret_cast<MSG*>(lParam);
            if (msg->message == WM_SYSCOMMAND &&
                msg->wParam  == SC_SCREENSAVE) {
                // broadcast screen saver started message
                PostThreadMessage(g_threadID,
                                SYNERGY_MSG_SCREEN_SAVER, TRUE, 0);
            }
        }
        if (g_mode == kHOOK_RELAY_EVENTS) {
            MSG* msg = reinterpret_cast<MSG*>(lParam);
            if (g_wheelSupport == kWheelOld && msg->message == g_wmMouseWheel) {
                // post message to our window
                PostThreadMessage(g_threadID,
                                SYNERGY_MSG_MOUSE_WHEEL,
                                static_cast<SInt16>(msg->wParam & 0xffffu), 0);

                // zero out the delta in the message so it's (hopefully)
                // ignored
                msg->wParam = 0;
            }
        }
    }

    return CallNextHookEx(g_getMessage, code, wParam, lParam);
}

#if (_WIN32_WINNT >= 0x0400) && defined(_MSC_VER) && !NO_LOWLEVEL_HOOKS

//
// low-level keyboard hook -- this allows us to capture and handle
// alt+tab, alt+esc, ctrl+esc, and windows key hot keys.  on the down
// side, key repeats are not reported to us.
//

#if !NO_GRAB_KEYBOARD
static
LRESULT CALLBACK
keyboardLLHook(int code, WPARAM wParam, LPARAM lParam)
{
    if (code >= 0) {
        // decode the message
        KBDLLHOOKSTRUCT* info = reinterpret_cast<KBDLLHOOKSTRUCT*>(lParam);
        WPARAM wParam = info->vkCode;
        LPARAM lParam = 1;                          // repeat code
        lParam      |= (info->scanCode << 16);      // scan code
        if (info->flags & LLKHF_EXTENDED) {
            lParam  |= (1lu << 24);                 // extended key
        }
        if (info->flags & LLKHF_ALTDOWN) {
            lParam  |= (1lu << 29);                 // context code
        }
        if (info->flags & LLKHF_UP) {
            lParam  |= (1lu << 31);                 // transition
        }
        // FIXME -- bit 30 should be set if key was already down but
        // we don't know that info.  as a result we'll never generate
        // key repeat events.

        // handle the message
        if (keyboardHookHandler(wParam, lParam)) {
            return 1;
        }
    }

    return CallNextHookEx(g_keyboardLL, code, wParam, lParam);
}
#endif

//
// low-level mouse hook -- this allows us to capture and handle mouse
// events very early.  the earlier the better.
//

static
LRESULT CALLBACK
mouseLLHook(int code, WPARAM wParam, LPARAM lParam)
{
    if (code >= 0) {
        // decode the message
        MSLLHOOKSTRUCT* info = reinterpret_cast<MSLLHOOKSTRUCT*>(lParam);
        SInt32 x = static_cast<SInt32>(info->pt.x);
        SInt32 y = static_cast<SInt32>(info->pt.y);
        SInt32 w = static_cast<SInt16>(HIWORD(info->mouseData));

        // handle the message
        if (mouseHookHandler(wParam, x, y, w)) {
            return 1;
        }
    }

    return CallNextHookEx(g_mouseLL, code, wParam, lParam);
}

#endif

static
EWheelSupport
getWheelSupport()
{
    // get operating system
    OSVERSIONINFO info;
    info.dwOSVersionInfoSize = sizeof(info);
    if (!GetVersionEx(&info)) {
        return kWheelNone;
    }

    // see if modern wheel is present
    if (GetSystemMetrics(SM_MOUSEWHEELPRESENT)) {
        // note if running on win2k
        if (info.dwPlatformId   == VER_PLATFORM_WIN32_NT &&
            info.dwMajorVersion == 5 &&
            info.dwMinorVersion == 0) {
            return kWheelWin2000;
        }
        return kWheelModern;
    }

    // not modern.  see if we've got old-style support.
#if defined(MSH_WHEELSUPPORT)
    UINT wheelSupportMsg    = RegisterWindowMessage(MSH_WHEELSUPPORT);
    HWND wheelSupportWindow = FindWindow(MSH_WHEELMODULE_CLASS,
                                        MSH_WHEELMODULE_TITLE);
    if (wheelSupportWindow != NULL && wheelSupportMsg != 0) {
        if (SendMessage(wheelSupportWindow, wheelSupportMsg, 0, 0) != 0) {
            g_wmMouseWheel = RegisterWindowMessage(MSH_MOUSEWHEEL);
            if (g_wmMouseWheel != 0) {
                return kWheelOld;
            }
        }
    }
#endif

    // assume modern.  we don't do anything special in this case
    // except respond to WM_MOUSEWHEEL messages.  GetSystemMetrics()
    // can apparently return FALSE even if a mouse wheel is present
    // though i'm not sure exactly when it does that (WinME returns
    // FALSE for my logitech USB trackball).
    return kWheelModern;
}


//
// external functions
//

BOOL WINAPI
DllMain(HINSTANCE instance, DWORD reason, LPVOID)
{
    if (reason == DLL_PROCESS_ATTACH) {
        DisableThreadLibraryCalls(instance);
        if (g_processID == 0) {
            g_hinstance = instance;
            g_processID = GetCurrentProcessId();
        }
    }
    else if (reason == DLL_PROCESS_DETACH) {
        if (g_processID == GetCurrentProcessId()) {
            uninstall();
            uninstallScreenSaver();
            g_processID = 0;
            g_hinstance = NULL;
        }
    }
    return TRUE;
}

extern "C" {

// VS2005 hack to not link with the CRT
#if _MSC_VER >= 1400
BOOL WINAPI _DllMainCRTStartup(
        HINSTANCE instance, DWORD reason, LPVOID lpreserved)
{
  return DllMain(instance, reason, lpreserved);
}

// VS2005 is a bit more bright than VC6 and optimize simple copy loop to
// intrinsic memcpy.
void *  __cdecl memcpy(void * _Dst, const void * _Src, size_t _MaxCount)
{
  void * _DstBackup = _Dst;
  switch (_MaxCount & 3) {
  case 3:
    ((char*)_Dst)[0] = ((char*)_Src)[0];
    ++(char*&)_Dst;
    ++(char*&)_Src;
    --_MaxCount;
  case 2:
    ((char*)_Dst)[0] = ((char*)_Src)[0];
    ++(char*&)_Dst;
    ++(char*&)_Src;
    --_MaxCount;
  case 1:
    ((char*)_Dst)[0] = ((char*)_Src)[0];
    ++(char*&)_Dst;
    ++(char*&)_Src;
    --_MaxCount;
    break;
  case 0:
    break;

  default:
    __assume(0);
    break;
  }

  // I think it's faster on intel to deference than modify the pointer.
  const size_t max = _MaxCount / sizeof(UINT_PTR);
  for (size_t i = 0; i < max; ++i) {
    ((UINT_PTR*)_Dst)[i] = ((UINT_PTR*)_Src)[i];
  }

  (UINT_PTR*&)_Dst += max;
  (UINT_PTR*&)_Src += max;

  switch (_MaxCount & 3) {
  case 3:
    ((char*)_Dst)[0] = ((char*)_Src)[0];
    ++(char*&)_Dst;
    ++(char*&)_Src;
  case 2:
    ((char*)_Dst)[0] = ((char*)_Src)[0];
    ++(char*&)_Dst;
    ++(char*&)_Src;
  case 1:
    ((char*)_Dst)[0] = ((char*)_Src)[0];
    ++(char*&)_Dst;
    ++(char*&)_Src;
    break;
  case 0:
    break;

  default:
    __assume(0);
    break;
  }

  return _DstBackup;
}
#endif

int
init(DWORD threadID)
{
    assert(g_hinstance != NULL);

    // try to open process that last called init() to see if it's
    // still running or if it died without cleaning up.
    if (g_processID != 0 && g_processID != GetCurrentProcessId()) {
        HANDLE process = OpenProcess(STANDARD_RIGHTS_REQUIRED,
                                FALSE, g_processID);
        if (process != NULL) {
            // old process (probably) still exists so refuse to
            // reinitialize this DLL (and thus steal it from the
            // old process).
            CloseHandle(process);
            return 0;
        }

        // clean up after old process.  the system should've already
        // removed the hooks so we just need to reset our state.
        g_hinstance       = GetModuleHandle(_T("synrgyhk"));
        g_processID       = GetCurrentProcessId();
        g_wheelSupport    = kWheelNone;
        g_threadID        = 0;
        g_keyboard        = NULL;
        g_mouse           = NULL;
        g_getMessage      = NULL;
        g_keyboardLL      = NULL;
        g_mouseLL         = NULL;
        g_screenSaver     = false;
    }

    // save thread id.  we'll post messages to this thread's
    // message queue.
    g_threadID  = threadID;

    // set defaults
    g_mode      = kHOOK_DISABLE;
    g_zoneSides = 0;
    g_zoneSize  = 0;
    g_xScreen   = 0;
    g_yScreen   = 0;
    g_wScreen   = 0;
    g_hScreen   = 0;

    return 1;
}

int
cleanup(void)
{
    assert(g_hinstance != NULL);

    if (g_processID == GetCurrentProcessId()) {
        g_threadID = 0;
    }

    return 1;
}

EHookResult
install()
{
    assert(g_hinstance  != NULL);
    assert(g_keyboard   == NULL);
    assert(g_mouse      == NULL);
    assert(g_getMessage == NULL || g_screenSaver);

    // must be initialized
    if (g_threadID == 0) {
        return kHOOK_FAILED;
    }

    // discard old dead keys
    g_deadVirtKey = 0;
    g_deadLParam  = 0;

    // reset fake input flag
    g_fakeInput = false;

    // check for mouse wheel support
    g_wheelSupport = getWheelSupport();

    // install GetMessage hook (unless already installed)
    if (g_wheelSupport == kWheelOld && g_getMessage == NULL) {
        g_getMessage = SetWindowsHookEx(WH_GETMESSAGE,
                                &getMessageHook,
                                g_hinstance,
                                0);
    }

    // install low-level hooks.  we require that they both get installed.
#if (_WIN32_WINNT >= 0x0400) && defined(_MSC_VER) && !NO_LOWLEVEL_HOOKS
    g_mouseLL = SetWindowsHookEx(WH_MOUSE_LL,
                                &mouseLLHook,
                                g_hinstance,
                                0);
#if !NO_GRAB_KEYBOARD
    g_keyboardLL = SetWindowsHookEx(WH_KEYBOARD_LL,
                                &keyboardLLHook,
                                g_hinstance,
                                0);
    if (g_mouseLL == NULL || g_keyboardLL == NULL) {
        if (g_keyboardLL != NULL) {
            UnhookWindowsHookEx(g_keyboardLL);
            g_keyboardLL = NULL;
        }
        if (g_mouseLL != NULL) {
            UnhookWindowsHookEx(g_mouseLL);
            g_mouseLL = NULL;
        }
    }
#endif
#endif

    // install regular hooks
    if (g_mouseLL == NULL) {
        g_mouse = SetWindowsHookEx(WH_MOUSE,
                                &mouseHook,
                                g_hinstance,
                                0);
    }
#if !NO_GRAB_KEYBOARD
    if (g_keyboardLL == NULL) {
        g_keyboard = SetWindowsHookEx(WH_KEYBOARD,
                                &keyboardHook,
                                g_hinstance,
                                0);
    }
#endif

    // check that we got all the hooks we wanted
    if ((g_getMessage == NULL && g_wheelSupport == kWheelOld) ||
#if !NO_GRAB_KEYBOARD
        (g_keyboardLL == NULL && g_keyboard     == NULL) ||
#endif
        (g_mouseLL    == NULL && g_mouse        == NULL)) {
        uninstall();
        return kHOOK_FAILED;
    }

    if (g_keyboardLL != NULL || g_mouseLL != NULL) {
        g_hookThread = GetCurrentThreadId();
        return kHOOK_OKAY_LL;
    }

    return kHOOK_OKAY;
}

int
uninstall(void)
{
    assert(g_hinstance != NULL);

    // discard old dead keys
    g_deadVirtKey = 0;
    g_deadLParam  = 0;

    // detach from thread
    detachThread();

    // uninstall hooks
    if (g_keyboardLL != NULL) {
        UnhookWindowsHookEx(g_keyboardLL);
        g_keyboardLL = NULL;
    }
    if (g_mouseLL != NULL) {
        UnhookWindowsHookEx(g_mouseLL);
        g_mouseLL = NULL;
    }
    if (g_keyboard != NULL) {
        UnhookWindowsHookEx(g_keyboard);
        g_keyboard = NULL;
    }
    if (g_mouse != NULL) {
        UnhookWindowsHookEx(g_mouse);
        g_mouse = NULL;
    }
    if (g_getMessage != NULL && !g_screenSaver) {
        UnhookWindowsHookEx(g_getMessage);
        g_getMessage = NULL;
    }
    g_wheelSupport = kWheelNone;

    return 1;
}

int
installScreenSaver(void)
{
    assert(g_hinstance != NULL);

    // must be initialized
    if (g_threadID == 0) {
        return 0;
    }

    // generate screen saver messages
    g_screenSaver = true;

    // install hook unless it's already installed
    if (g_getMessage == NULL) {
        g_getMessage = SetWindowsHookEx(WH_GETMESSAGE,
                                &getMessageHook,
                                g_hinstance,
                                0);
    }

    return (g_getMessage != NULL) ? 1 : 0;
}

int
uninstallScreenSaver(void)
{
    assert(g_hinstance != NULL);

    // uninstall hook unless the mouse wheel hook is installed
    if (g_getMessage != NULL && g_wheelSupport != kWheelOld) {
        UnhookWindowsHookEx(g_getMessage);
        g_getMessage = NULL;
    }

    // screen saver hook is no longer installed
    g_screenSaver = false;

    return 1;
}

void
setSides(UInt32 sides)
{
    g_zoneSides = sides;
}

void
setZone(SInt32 x, SInt32 y, SInt32 w, SInt32 h, SInt32 jumpZoneSize)
{
    g_zoneSize = jumpZoneSize;
    g_xScreen  = x;
    g_yScreen  = y;
    g_wScreen  = w;
    g_hScreen  = h;
}

void
setMode(EHookMode mode)
{
    if (mode == g_mode) {
        // no change
        return;
    }
    g_mode = mode;
}

}