ICopyHook是一个用于创建拷贝钩子处理程序COM接口，它决定一个文件夹或者打印机对象是否可以被移动，拷贝，重命名或删除。Shell在执行这些操作之前，会调用ICopyHook接口的CopyCallback方法对它们进行验证。CopyCallback返回一个int值指示Shell是否应该继续执行这个操作。返回值IDYES表示继续，而返回值IDNO和IDCANCEL则表示终止。
一个文件夹对象可以安装多个拷贝钩子处理程序。如果出现这种情况，Shell会依次调用每个处理程序。只有当每个处理程序都返回IDYES时，Shell才真正执行用户请求的操作。
拷贝钩子处理程序的作用是在上述四种操作执行前对它们进行验证，但是Shell并不会把操作的结果通知给拷贝钩子处理程序。而windows提供的API函数FindFirstChangeNotification和FindNextChangeNotification却可以实现这个功能。因此，只有把这种两种方法结合起来，才能对一个文件夹的状态进行完全的监控。
拷贝钩子处理程序实现并不困难，首先创建一个作为进程内组件的COM对象，它只需要暴露一个ICopyHook接口（当然还有IUnknown）。然后用regsrv32.exe注册这个COM组件。最后一步是向Shell注册你的这个拷贝钩子处理程序，方法是在注册表HKEY_CLASSES_ROOT/Directory/Shellex/CopyHookHandlers下创建一个名称任意的sub key，在此sub key中创建一个类型为REG_SZ的项并将你的COM对象的CLSID作为它的默认值就可以了。
下面就是一个拷贝钩子的实现程序
// CCopyHook.h
//CCopyHook类实现了ICopyHook接口，CClassFactory实现了IClassFactory接口
#include <shlobj.h>
class CCopyHook: public ICopyHook
{
public:
CCopyHook():m_refcnt(0) { }
STDMETHODIMP QueryInterface(REFIID iid,void** ppvObject);
STDMETHODIMP_(ULONG) AddRef();
STDMETHODIMP_(ULONG) Release();
STDMETHODIMP_(UINT) CopyCallback(HWND hwnd,UINT wFunc,UINT wFlags,
LPCTSTR pszSrcFile,DWORD dwSrcAttribs,
LPCTSTR pszDestFile,DWORD dwDestAttribs);
private:
int m_refcnt;
};
class CClassFactory:public IClassFactory
{
public:
CClassFactory():m_refcnt(0) { }
STDMETHODIMP QueryInterface(REFIID iid,void** ppvObject);
STDMETHODIMP_(ULONG) AddRef();
STDMETHODIMP_(ULONG) Release();
STDMETHODIMP CreateInstance(IUnknown * pUnkOuter,REFIID riid,void ** ppvObject);
STDMETHODIMP LockServer(BOOL fLock);
private:
int m_refcnt;
};
// CCopyHook.cpp
//CCopyHook对象和CClassFactory对象的实现文件
#include <stdio.h>
#include "CCopyHook.h"
extern LONG nLocks; //对象计数，用于DllCanUnloadNow
ULONG __stdcall CCopyHook::AddRef(){
if(m_refcnt==0)
nLocks++;
m_refcnt++;
return m_refcnt;
}
ULONG __stdcall CCopyHook::Release(){
int nNewCnt=--m_refcnt;
if(nNewCnt<=0){
nLocks--;
delete this;
}
return nNewCnt;
}
HRESULT __stdcall CCopyHook::QueryInterface(REFIID iid,void** ppvObject){
if(iid==IID_IUnknown)
*ppvObject=static_cast<IUnknown*>(this);
else
if(iid==IID_IShellCopyHook)
*ppvObject=static_cast<ICopyHook*>(this);
else
return E_NOINTERFACE;
reinterpret_cast<IUnknown*>(*ppvObject)->AddRef();
return S_OK;
}
//这就是CopyCallback方法，拷贝钩子的所有功能由它实现。参数的具体值参看MSDN
UINT __stdcall CCopyHook::CopyCallback(HWND hwnd,UINT wFunc,UINT wFlags,
LPCTSTR pszSrcFile,DWORD dwSrcAttribs,
LPCTSTR pszDestFile,DWORD dwDestAttribs){
char szMessage[MAX_PATH+14];
sprintf(szMessage,"对%s进行的操作，是否继续？",pszSrcFile);
return MessageBox(NULL,szMessage,"确认",MB_YESNO|MB_ICONEXCLAMATION);
}
ULONG __stdcall CClassFactory::AddRef(){
if(m_refcnt==0)
nLocks++;
m_refcnt++;
return m_refcnt;
}
ULONG __stdcall CClassFactory::Release(){
int nNewCnt=--m_refcnt;
if(nNewCnt<=0){
nLocks--;
delete this;
}
return nNewCnt;
}
HRESULT __stdcall CClassFactory::QueryInterface(REFIID iid,void** ppvObject){
if(iid==IID_IUnknown)
*ppvObject=static_cast<IUnknown*>(this);
else
if(iid==IID_IClassFactory)
*ppvObject=static_cast<IClassFactory*>(this);
else
return E_NOINTERFACE;
reinterpret_cast<IUnknown*>(*ppvObject)->AddRef();
return S_OK;
}
HRESULT __stdcall CClassFactory::CreateInstance(IUnknown* pUnkownOuter,REFIID riid,void** ppvObj){
if(pUnkownOuter!=NULL)
return CLASS_E_NOAGGREGATION;
CCopyHook* pObj=new CCopyHook;
pObj->AddRef();
HRESULT hr=pObj->QueryInterface(riid,ppvObj);
pObj->Release();
return hr;
}
HRESULT __stdcall CClassFactory::LockServer(BOOL fLock){
if(fLock)
nLocks++;
else
nLocks--;
return S_OK;
}
// main.cpp
//主要实现了几个COM对象标准的导出函数。
#include <objbase.h>
#include <olectl.h>
#include "CCopyHook.h"
//这是要添加到注册表中的项，注意如果你要使用这段代码，应该用UUIDGEN.exe生成一
//个新的CLSID。
const char* szRegTable[][3]={
{"CLSID//{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}",0,"CopyHook"},
{"CLSID//{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}//InProcServer32",0,(const char*)-1},
{"CLSID//{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}//InProcServer32","ThreadingModel","Apartment"},
{"CLSID//{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}//ProgID",0,"webber84.CopyHook.1"},
{"webber84.CopyHook.1",0,"CopyHook"},
{"webber84.CopyHook.1//CLSID",0,"{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}"}};
HMODULE hInstance=NULL;
LONG nLocks=0;
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
){
if(ul_reason_for_call==DLL_PROCESS_ATTACH)
hInstance=(HMODULE)hModule;
return TRUE;
}
STDAPI DllUnregisterServer(){
HRESULT hr=S_OK; LONG ret=0;
int items=sizeof(szRegTable)/sizeof(szRegTable[0]);
for(int i=items-1;i>=0;i--){
const char* szKeyName=szRegTable[i][0];
if( (i==items-1) || stricmp(szRegTable[i+1][0],szKeyName)!=0)
ret=RegDeleteKey(HKEY_CLASSES_ROOT,szKeyName);
if(ret!=ERROR_SUCCESS)
hr=SELFREG_E_CLASS;
}
return hr;
}
//可重用的DllRegisterServer函数，只要照上面的格式把注册表项放到一个数组中，就可以//用这段代码完成对任意组件的注册。
STDAPI DllRegisterServer(void){
HRESULT hr=S_OK;
int items=sizeof(szRegTable)/sizeof(szRegTable[0]);
char szDllPath[MAX_PATH];
GetModuleFileName(hInstance,szDllPath,MAX_PATH);
for(int i=0;i<items && SUCCEEDED(hr);i++){
const char* szKeyName=szRegTable[i][0];
const char* szValueName=szRegTable[i][1];
const char* szValue=szRegTable[i][2];
if(szValue==(const char*)-1)
szValue=szDllPath;
HKEY hKey;
LONG ret=RegCreateKey(HKEY_CLASSES_ROOT,szKeyName,&hKey);
if(ret==ERROR_SUCCESS){
RegSetValueEx(hKey,szValueName,0,REG_SZ,(const BYTE*)szValue,
strlen(szValue)+1);
RegCloseKey(hKey);
}
if(ret!=ERROR_SUCCESS){
hr=SELFREG_E_CLASS;
DllUnregisterServer();
}
}
return hr;
}
STDAPI DllGetClassObject (REFCLSID rclsid, REFIID riid, void** ppvObj) {
HRESULT hr = E_OUTOFMEMORY;
*ppvObj = NULL;
CClassFactory *pClassFactory = new CClassFactory;
if (pClassFactory != NULL)
hr = pClassFactory->QueryInterface(riid, ppvObj);
return hr;
}
STDAPI DllCanUnloadNow(){
return nLocks==0 ? S_OK : S_FALSE;
}
