GetWindowLong() - 使用Creators Update引入的行为更改会破坏我的win32应用程序

Question

GetWindowLong() - 使用Creators Update引入的行为更改会破坏我的win32应用程序

最近对Windows 10进行的Creator更新破坏了我使用Win32 API GetWindowLong()的应用程序代码.

在Windows 10 Creator Update之前,一个进程(比如进程A)能够在另一个进程的窗口句柄(比如进程B)上调用GetWindowWord()/ GetWindowLong()API,即使在某些系统中阻止了进程B(主线程)调用(例如等待释放互斥锁).因此,尽管进程B被阻止,但进程A能够成功地使用这些API查询进程B拥有的窗口的保留内存.

但是,在Windows 10上应用创建者更新时,当进程B(主线程)被阻止时,进程A在属于进程B的窗口上调用这些API时会被阻止.

我通过创建2个代表进程A和进程B的独立Win32应用程序来模拟这种情况.在应用了创建者更新的Windows 10系统上,进程A在属于进程B的窗口上调用GetWindowLong()/ GetWindowWord()时挂起进程B(主线程)正在等待互斥锁.换句话说,对GetWindowLong()/ GetWindowWord()的调用从未返回,从而使进程A挂起.

但是,当我在没有Creators Update或早期版本(如Windows 7)的Windows 10系统上使用我的独立应用程序测试相同的场景时,对进程A中的GetWindowLong()/ GetWindowWord()API的调用成功返回进程B正在等待一个互斥锁被释放.

为了演示上述问题,这里是进程A和进程B的代码.要查看问题,请运行进程A和进程B.然后,找出进程B窗口的窗口句柄(例如,使用Spy ++)然后粘贴它进入进程A的窗口的编辑字段.然后单击"确定".将显示一个消息框,显示在进程B的窗口的额外内存中设置的LONG值(使用SetWindowLong()).到现在为止还挺好.现在,进入B的窗口,点击"Block"按钮使其挂起.这将使进程"B"(主GUI线程)等待永远不会被释放的互斥锁,因此进程B将挂起.

现在,返回进程A的窗口并再次单击OK(假设编辑字段仍然具有您之前粘贴的进程B的窗口句柄).

现在,这是行为上的差异:

在Windows 10上没有创建者更新和早期的Windows版本(如Windows 7),就像以前一样(即进程B没有挂起),一个消息框显示在进程B的窗口的额外内存中设置的LONG值(使用SetWindowLong())显示.

在带有Creators Update的Windows 10上,进程A挂起,因为使用进程B的窗口句柄调用SetWindowLong()永远不会返回使进程A挂起.

请建议我如何绕过Windows 10 Creators Update上的这种行为更改,以便我的应用程序不会挂起.任何想法/帮助将不胜感激.

这是进程A的代码.

/* Process A */
#include <windows.h>
#include <stdio.h>
#include <commctrl.h>

int count = 0;
int count1 = 0;
TCHAR str[1000];

LRESULT CALLBACK WindowFunc(HWND,UINT,WPARAM,LPARAM);

HWND g_hwndEdit, g_hwndButton;

#define ID_EDIT (3456)

#define ID_OK (3457)

TCHAR szWinName[] = TEXT("MyWin");

HINSTANCE g_hInst = NULL;

int WINAPI WinMain(HINSTANCE hThisInst,HINSTANCE hPrevInst,LPSTR lpszArgs,int nWinMode)
{
    HWND hwnd;
    MSG msg;
    WNDCLASSEX wcl;
    g_hInst = hThisInst;
    wcl.cbSize = sizeof(WNDCLASSEX);
    wcl.hInstance = hThisInst;
    wcl.lpszClassName = szWinName;
    wcl.lpfnWndProc = WindowFunc;
    wcl.style = CS_HREDRAW|CS_VREDRAW;
    wcl.hIcon = LoadIcon(NULL,IDI_APPLICATION);
    wcl.hIconSm = NULL;
    wcl.hCursor = LoadCursor(NULL,IDC_ARROW);
    wcl.lpszMenuName = NULL;
    wcl.cbClsExtra = 0;
    wcl.cbWndExtra = 44;
    wcl.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
    if(!RegisterClassEx(&wcl)) return 0;
    hwnd = CreateWindowEx(
        WS_EX_WINDOWEDGE,
        szWinName,
        "Process A",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        HWND_DESKTOP,
        NULL,
        hThisInst,
        NULL
        );    
    ShowWindow(hwnd,nWinMode);
    UpdateWindow(hwnd);

    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
LRESULT CALLBACK WindowFunc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)
{
    LONG l;    
    HWND hwndOther = hwnd;
    char s[] = "Paste the window handle (in HEX) of Process B's window on which you wish to call GetWindowLong() in the edit field and click on OK.";

    HDC hdc;
    PAINTSTRUCT ps;
    static int cxClient = 0, cyClient = 0;

    char btnText[1001];

    switch(message){

    case WM_CREATE:

        g_hwndEdit = CreateWindow ("edit", NULL,
                         WS_CHILD | WS_VISIBLE | WS_HSCROLL | WS_VSCROLL |
                                   WS_BORDER | ES_LEFT,
                         200, 200, 200, 200, hwnd, (HMENU)ID_EDIT,
                         g_hInst, NULL) ;

        g_hwndButton = CreateWindow(                       
                        "Button",
                        "OK",
                        WS_CHILD|WS_VISIBLE,
                        500,
                        200,
                        150,
                        50,
                        hwnd,
                        (HMENU)ID_OK,
                        g_hInst,
                        NULL
                        );

        return 0;

    case WM_SIZE:

        cxClient = LOWORD(lParam);
        cyClient = HIWORD(lParam);

        return 0;

    case WM_PAINT:

        hdc = BeginPaint(hwnd, &ps);

        TextOut(hdc, 10, 100, s, strlen(s));

        EndPaint(hwnd, &ps);

        return 0;


    case WM_COMMAND:
        {
            if (HIWORD(wParam) == BN_CLICKED && LOWORD(wParam) == ID_OK)
            {
                GetWindowText(g_hwndEdit, btnText, 1000);
                sscanf(btnText, "%x", &hwndOther);
                l = GetWindowLong(hwndOther, 24);
                sprintf(str, "The LONG value at offset 24 of the window with handle 0x%x is %d.", hwndOther, l);
                MessageBox(hwnd, str, "", 0);
            }
        }

        break;

    case WM_DESTROY:

        PostQuitMessage(0);
        return 0;        
    }
    return DefWindowProc(hwnd,message,wParam,lParam);
}

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这是进程B的代码:

/* Process B */
#include <windows.h>
#include <stdio.h>
#include <commctrl.h>

int count = 0;
int count1 = 0;
TCHAR str[1000];

LRESULT CALLBACK WindowFunc(HWND,UINT,WPARAM,LPARAM);

TCHAR szWinName[] = TEXT("MyWin");

HINSTANCE g_hInst = NULL;

HANDLE g_hThread, g_hMutex;

HWND g_hwndButton;

#define ID_BUTTON (3456)

//worker thread fn
DWORD WINAPI ThreadFunc(LPVOID p)
{
    g_hMutex = CreateMutex(NULL, TRUE, "HELLO_MUTEX");
    // this worker thread now owns the above created mutex and goes into an infinite loop so that
    // the mutex is never released
    while (1){}
    return 0;
}

// main (GUI) thread
int WINAPI WinMain(HINSTANCE hThisInst,HINSTANCE hPrevInst,LPSTR lpszArgs,int nWinMode)
{    

    HANDLE hThread;
    DWORD threadld;
    // create a worker thread that will create a mutex and then will go into an infinite loop making sure that the mutex is never released
    // and thus when the main (GUI) thread calls WaitForSingleObject() on this mutex handle, it is going to block forever.
    hThread = CreateThread(NULL,
                            0,
                            ThreadFunc,
                            0,
                            0,
                            &threadld);

    // make the main (GUI) thread sleep for 5 secs so that by the time it wakes up, the worker thread will have created the mutex and gone into an infinite loop
    Sleep(5000);
    HWND hwnd;
    MSG msg;
    WNDCLASSEX wcl;
    g_hInst = hThisInst;
    wcl.cbSize = sizeof(WNDCLASSEX);
    wcl.hInstance = hThisInst;
    wcl.lpszClassName = szWinName;
    wcl.lpfnWndProc = WindowFunc;
    wcl.style = CS_HREDRAW|CS_VREDRAW;
    wcl.hIcon = LoadIcon(NULL,IDI_APPLICATION);
    wcl.hIconSm = NULL;
    wcl.hCursor = LoadCursor(NULL,IDC_ARROW);
    wcl.lpszMenuName = NULL;
    wcl.cbClsExtra = 0;
    wcl.cbWndExtra = 44;
    wcl.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
    if(!RegisterClassEx(&wcl)) return 0;
    hwnd = CreateWindowEx(
        WS_EX_WINDOWEDGE,
        szWinName,
        "Process B",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        HWND_DESKTOP,
        NULL,
        hThisInst,
        NULL
        );
    SetWindowLong(hwnd, 24, 135678);
    ShowWindow(hwnd,nWinMode);
    UpdateWindow(hwnd);

    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
LRESULT CALLBACK WindowFunc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)
{
    char strr[1000];    
    char s[] = "Click on the \"Block\" button below to make the main (GUI) thread block by waiting on a mutex forever since the mutex will never be released.";
    HWND hwndOther = hwnd;

    HDC hdc;
    PAINTSTRUCT ps;
    static int cxClient = 0, cyClient = 0;

    switch(message){

    case WM_CREATE:


        sprintf(strr, "Window created - handle is %x.\n", hwnd);
        OutputDebugString(strr);

        g_hwndButton = CreateWindow(                       
                        "Button",
                        "Block",
                        WS_CHILD|WS_VISIBLE,
                        10,
                        120,
                        50,
                        50,
                        hwnd,
                        (HMENU)ID_BUTTON,
                        g_hInst,
                        NULL
                        );

        return 0;

    case WM_SIZE:

        cxClient = LOWORD(lParam);
        cyClient = HIWORD(lParam);

        return 0;

    case WM_PAINT:

        hdc = BeginPaint(hwnd, &ps);

        TextOut(hdc, 10, 100, s, strlen(s));

        EndPaint(hwnd, &ps);

        return 0;

    case WM_COMMAND:
        {
            if (HIWORD(wParam) == BN_CLICKED && LOWORD(wParam) == ID_BUTTON)
            {                
                MessageBox(hwnd, "Main (GUI) Thread going in blocking state by waiting for mutex forever now", "", 0);
                WaitForSingleObject(g_hMutex, INFINITE);              
            }
        }

        break;

    case WM_DESTROY:

        PostQuitMessage(0);
        return 0;        
    }
    return DefWindowProc(hwnd,message,wParam,lParam);
}

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Answer 1

Anu*_*rma 0

我想我找到了解决方案，即在进程 B 中使用 MsgWaitForMultipleObjects() ，以便除了等待互斥体之外，它还继续在队列中查找消息。通过这样做，进程A中对进程B的窗口句柄进行的GetWindowLong()调用将正常返回而不会阻塞，从而解决问题。

这是进程 B 的更新代码，更改在于“阻止”按钮单击处理 WM_COMMAND 情况（进程 A 代码保持不变）：

#include <windows.h>
#include <stdio.h>
#include <commctrl.h>

int count = 0;
int count1 = 0;
TCHAR str[1000];

LRESULT CALLBACK WindowFunc(HWND,UINT,WPARAM,LPARAM);

TCHAR szWinName[] = TEXT("MyWin");

HINSTANCE g_hInst = NULL;

HANDLE g_hThread, g_hMutex;

HWND g_hwndButton;

#define ID_BUTTON (3456)

//worker thread fn
DWORD WINAPI ThreadFunc(LPVOID p)
{
    g_hMutex = CreateMutex(NULL, TRUE, "HELLO_MUTEX");
    // this worker thread now owns the above created mutex and goes into an infinite loop so that
    // the mutex is never released
    while (1){}
    return 0;
}

// main (GUI) thread
int WINAPI WinMain(HINSTANCE hThisInst,HINSTANCE hPrevInst,LPSTR lpszArgs,int nWinMode)
{    

    HANDLE hThread;
    DWORD threadld;
    // create a worker thread that will create a mutex and then will go into an infinite loop making sure that the mutex is never released
    // and thus when the main (GUI) thread calls WaitForSingleObject() on this mutex handle, it is going to block forever.
    hThread = CreateThread(NULL,
                            0,
                            ThreadFunc,
                            0,
                            0,
                            &threadld);

    // make the main (GUI) thread sleep for 5 secs so that by the time it wakes up, the worker thread will have created the mutex and gone into an infinite loop
    Sleep(5000);
    HWND hwnd;
    MSG msg;
    WNDCLASSEX wcl;
    g_hInst = hThisInst;
    wcl.cbSize = sizeof(WNDCLASSEX);
    wcl.hInstance = hThisInst;
    wcl.lpszClassName = szWinName;
    wcl.lpfnWndProc = WindowFunc;
    wcl.style = CS_HREDRAW|CS_VREDRAW;
    wcl.hIcon = LoadIcon(NULL,IDI_APPLICATION);
    wcl.hIconSm = NULL;
    wcl.hCursor = LoadCursor(NULL,IDC_ARROW);
    wcl.lpszMenuName = NULL;
    wcl.cbClsExtra = 0;
    wcl.cbWndExtra = 44;
    wcl.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
    if(!RegisterClassEx(&wcl)) return 0;
    hwnd = CreateWindowEx(
        WS_EX_WINDOWEDGE,
        szWinName,
        "Process B",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        HWND_DESKTOP,
        NULL,
        hThisInst,
        NULL
        );
    SetWindowLong(hwnd, 24, 135678);
    ShowWindow(hwnd,nWinMode);
    UpdateWindow(hwnd);

    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}

BOOL waitWithMessageLoop(HANDLE hMutex, BOOL &bExit)
{
    BOOL bContinue = TRUE;
    bExit = FALSE;
    while(bContinue)
    {
        DWORD dwReturn = ::MsgWaitForMultipleObjects(1, &hMutex, FALSE, INFINITE, QS_ALLINPUT);
        if(dwReturn == WAIT_OBJECT_0)
        {
            // our mutex got released
            bContinue = FALSE;
        }
        else if(dwReturn == WAIT_OBJECT_0 + 1)
        {
            MSG msg;
            while(::PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
            {
                if (msg.message == WM_QUIT)
                {
                    bExit = TRUE;
                    bContinue = FALSE;
                    break;
                }
                ::TranslateMessage(&msg);
                ::DispatchMessage(&msg);
            }
        }
        else
        {
            // MsgWaitForMultipleObjects() returned error
            return FALSE;
        }
    }
    return TRUE;
}


LRESULT CALLBACK WindowFunc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)
{
    char strr[1000];    
    char s[] = "Click on the \"Block\" button below to make the main (GUI) thread block by waiting on a mutex forever since the mutex will never be released.";
    HWND hwndOther = hwnd;

    HDC hdc;
    PAINTSTRUCT ps;
    static int cxClient = 0, cyClient = 0;

    switch(message){

    case WM_CREATE:


        sprintf(strr, "Window created - handle is %x.\n", hwnd);
        OutputDebugString(strr);

        g_hwndButton = CreateWindow(                       
                        "Button",
                        "Block",
                        WS_CHILD|WS_VISIBLE,
                        10,
                        120,
                        50,
                        50,
                        hwnd,
                        (HMENU)ID_BUTTON,
                        g_hInst,
                        NULL
                        );

        return 0;

    case WM_SIZE:

        cxClient = LOWORD(lParam);
        cyClient = HIWORD(lParam);

        return 0;

    case WM_PAINT:

        hdc = BeginPaint(hwnd, &ps);

        TextOut(hdc, 10, 100, s, strlen(s));

        EndPaint(hwnd, &ps);

        return 0;

    case WM_COMMAND:
        {
            if (HIWORD(wParam) == BN_CLICKED && LOWORD(wParam) == ID_BUTTON)
            {                
                MessageBox(hwnd, "Main (GUI) Thread going in blocking state by waiting for mutex forever now", "", 0);
                // disable the "Block" button
                EnableWindow(g_hwndButton, FALSE);
                //WaitForSingleObject(g_hMutex, INFINITE);// do NOT use this as this cause the GetWindowLong() call made in Process A to hang
                BOOL bExit = FALSE;
                waitWithMessageLoop(g_hMutex, bExit);
                if (bExit)
                {
                    PostQuitMessage(0);
                }
            }
        }

        break;

    case WM_DESTROY:

        PostQuitMessage(0);
        return 0;        
    }
    return DefWindowProc(hwnd,message,wParam,lParam);
}

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谢谢，--阿努拉格。

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