[Win32] ShellHook的实现

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启动Windows，加载Win32子系统，登录一个用户会话后，会启动Shell程序，默认是explorer.exe，就是我们看到的桌面和任务栏等，其实Shell是可以自定义的，我们完全可以自己编写一个Shell取代系统的Shell。下面我们来看看编写Windows Shell的核心技术之一——ShellHook。

ShellHook是什么？当一个窗口创建、激活、关闭时，explorer总是能够捕获相应的消息，并更新任务栏上，就是通过ShellHook实现的。

explorer总是能够捕获相应的消息，并更新任务栏上，最初，我猜测explorer是通过timer定时调用枚举窗口，或者使用全局消息钩子实现，但是这两种方法对系统资源的消耗是巨大的，其实，要想实现这一功能，使用ShellHook即方便又稳定，而且还没有资源占用大的问题。

完整示例源码如下（注释很详细）：

#include <windows.h>
#pragma comment(lib,"user32.lib")
#pragma comment(lib,"gdi32.lib")
//#pragma comment(linker,"/manifestdependency:\"type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='x86' publicKeyToken='6595b64144ccf1df' language='*'\"")

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);

WNDCLASS wc;
const TCHAR* AppName = TEXT("MyWindowClass1");

HWND hwnd1;
HWND edit2 = 0;

//定义ShellHook的消息
static UINT WM_SHELLHOOKMESSAGE;

int APIENTRY _tWinMain(_In_ HINSTANCE hInstance,
	_In_opt_ HINSTANCE hPrevInstance,
	_In_ LPTSTR    lpCmdLine,
	_In_ int       nCmdShow)
{
	//这里是在构建窗口类结构
	wc.style = CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc = WndProc;//窗口回调函数指针
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hInstance = hInstance;//实例句柄
	wc.hIcon = LoadIcon(hInstance, TEXT("ICON_1"));
	wc.hCursor = LoadCursor(NULL, IDC_ARROW);//默认指针
	wc.hbrBackground = (HBRUSH)(COLOR_WINDOW);//默认背景颜色
	wc.lpszMenuName = NULL;
	wc.lpszClassName = AppName;//窗口类名

	//注册窗口类
	if (!RegisterClass(&wc))
	{
		MessageBox(NULL, TEXT("注册窗口类失败!"), TEXT("错误"), MB_ICONERROR);
		return 0;
	}

	//创建窗口
	int style = WS_OVERLAPPEDWINDOW;
	hwnd1 = CreateWindowEx(WS_EX_TOPMOST, AppName, TEXT("ShellHook"), style, 50, 50, 500, 500, 0, NULL, hInstance, 0);
	if (hwnd1 == NULL)
	{
		MessageBox(NULL, TEXT("创建窗口失败!"), TEXT("错误"), MB_ICONERROR);
		return 0;
	}

	//显示、更新窗口
	ShowWindow(hwnd1, nCmdShow);
	UpdateWindow(hwnd1);

	//消息循环
	MSG msg;
	while (GetMessage(&msg, NULL, 0, 0))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return msg.wParam;
}

void AddEditText(TCHAR* string, HWND hwnd)//向edit control添加字符串
{
	int len = GetWindowTextLength(hwnd);//获取edit control字符个数
	SendMessage(hwnd, EM_SETSEL, len, len);//将选中设置为末尾
	SendMessage(hwnd, EM_REPLACESEL, 0, (LPARAM)string);//将末尾替换为指定的字符串
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	switch (uMsg){
	case WM_CREATE:
		//创建edit control
		edit2 = CreateWindowEx(WS_EX_CLIENTEDGE, TEXT("Edit"), TEXT(""), WS_CHILD | WS_VISIBLE | ES_MULTILINE | ES_WANTRETURN | WS_VSCROLL | ES_AUTOVSCROLL, 5, 5, 400, 450, hwnd, (HMENU)8, (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), NULL);
		SendMessage(edit2, WM_SETFONT, (WPARAM)GetStockObject(17), 0);

		//进行ShellHook
		WM_SHELLHOOKMESSAGE = RegisterWindowMessage(TEXT("SHELLHOOK"));
		if (!RegisterShellHookWindow(hwnd))MessageBox(hwnd, TEXT("shellhook失败"), TEXT(""), 0);

		break;
	case WM_DESTROY://窗口已经销毁
		PostQuitMessage(0);//退出消息循环，结束应用程序
		return 0;
		break;
	default:
		break;
	}
	//这里是处理ShellHook的回调
	HWND hwin;
	if (uMsg == WM_SHELLHOOKMESSAGE){
		TCHAR tmp[50] = {0};
		hwin = (HWND)lParam;//得到窗口句柄

		//判断Shell消息类型
		if (wParam == HSHELL_WINDOWACTIVATED || wParam == HSHELL_RUDEAPPACTIVATED){
			AddEditText(TEXT("[窗口激活]"), edit2);
			goto print;
		}
		if (wParam == HSHELL_WINDOWDESTROYED){
			AddEditText(TEXT("[窗口关闭]"), edit2);
			goto print;
		}
		goto end;
	print:
		//这里是判断一下窗口风格和扩展风格，如果是toolwindow或者子窗口可以直接过滤掉，但这里只是输出是特殊窗口，但不过滤
		DWORD style;
		style = GetWindowLongPtr(hwin, GWL_EXSTYLE);//获取窗口扩展风格
		if (style & WS_EX_TOOLWINDOW){//使用位与运算判断
			AddEditText(TEXT("ToolWindow "), edit2);
		}
		style = GetWindowLongPtr(hwin, GWL_STYLE);
		if (style & WS_CHILD){
			AddEditText(TEXT("Child "), edit2);
		}
		_itot((DWORD)hwin, tmp, 10);//将窗口句柄转换为TCHAR字符串
		AddEditText(tmp, edit2);
		AddEditText(TEXT(" - "), edit2);
		DWORD len = GetWindowTextLength(hwin);//获取窗口标题长度
		len = len * sizeof(TCHAR);//GetWindowTextLength得到的是字符数而不是字节数 
		//分配内存
		TCHAR* til = (TCHAR*)VirtualAlloc(NULL, len + 2, MEM_COMMIT, PAGE_READWRITE);//TCHAR* til = new TCHAR[len + 1];
		RtlZeroMemory(til, len + 2);//或者：til[len]='\0';
		GetWindowText(hwin, til, len/sizeof(TCHAR) + 2);//获取窗口标题
		AddEditText(til, edit2);
		AddEditText(TEXT("\r\n"), edit2);//添加换行符
		//释放资源
		VirtualFree(til, len + 2, MEM_DECOMMIT);//delete[] til;
		return 0;
	end:
		;
	}
	return DefWindowProc(hwnd, uMsg, wParam, lParam);//其他消息交给系统处理
}

效果图：