windows – GetWindowLong() – 使用Creators Update引入的行为

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),然后将其粘贴到进程A的窗口的编辑字段中.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,HWND_DESKTOP,NULL,hThisInst,NULL
        );    
    ShowWindow(hwnd,nWinMode);
    UpdateWindow(hwnd);

    while(GetMessage(&msg,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",WS_CHILD | WS_VISIBLE | WS_HSCROLL | WS_VSCROLL |
                                   WS_BORDER | ES_LEFT,200,hwnd,(HMENU)ID_EDIT,g_hInst,NULL) ;

        g_hwndButton = CreateWindow(                       
                        "Button","OK",WS_CHILD|WS_VISIBLE,500,150,50,(HMENU)ID_OK,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);
}

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,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,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,ThreadFunc,&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,"Process B",NULL
        );
    SetWindowLong(hwnd,24,135678);
    ShowWindow(hwnd,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",120,(HMENU)ID_BUTTON,&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,lParam);
}