Question

I am implementing a recursive registry delete using RegOpenKeyEx, RegDeleteKey and RegEnumKey.

Problem:: Though the code works perfectly fine for Vista x86/x64 and Win 7 x86/x64 but fails on XP for some keys in HKCR

Problem Area:: HKCR\Installer\Products\SomeKey

Error Code:: 87 (INVALID_PARAMETER)

Weird Behaviour:: Deletes the key the moment I open the key using REGEDIT.

Code::

static BOOL RcrsvRegDel( HKEY hKey, LPTSTR lpszSub )
{
BOOL    bRet = TRUE ;
LONG    lRet ;
DWORD   dwSize = MAX_PATH ;
TCHAR   szName[MAX_PATH] ;
TCHAR   szFullKey[MAX_PATH * 2] ;
HKEY    hKeySub = NULL ;
HRESULT hr = NULL ;

do{
    lRet = RegOpenKeyEx( hKey, lpszSub, 0, KEY_ENUMERATE_SUB_KEYS | DELETE, &hKeySub ) ;
    printf("RegOpenKey:: %S :: lRet = %ld\n", lpszSub, lRet) ;
    if( lRet != ERROR_SUCCESS )
    {
        if( lRet == ERROR_FILE_NOT_FOUND )
        {
            bRet = TRUE ;
            break ;
        }
        else
        {
            bRet = FALSE ;
            break ;
        }
    }

    while( ERROR_NO_MORE_ITEMS != (lRet = RegEnumKeyEx(hKeySub, 0, szName, &dwSize, NULL, NULL, NULL, NULL)) )
    {
        bRet = RcrsvRegDel( hKeySub, szName) ;
        if( bRet == FALSE )
            break ;
    }

    if( hKeySub != NULL )
    {
        RegCloseKey(hKeySub) ;
        hKeySub = NULL ;
    }

    lRet = RegDeleteKey( hKey, lpszSub ) ;
    printf("RegDelKey:: %S :: lRet = %ld\n", lpszSub, lRet) ;
    if( lRet == ERROR_SUCCESS )
    {
        bRet = TRUE ;
        break ;
    }
}while(0) ;
return bRet ;
}

Any idea whats goin on?

UPDATE::

I have also tried the samDesired Parameter with following flags

-KEY_READ

-KEY_READ | KEY_WRITE

-KEY_ENUMERATE_SUB_KEYS

-KEY_ENUMERATE_SUB_KEYS | DELETE

Neither of the above flag works 🙁

Answer 1

You can do like this. Take the flag as input parameter and pass one flag for the RegOpenKeyEx and again a set of flags when calling the recursive function. I have tried your code and it is working perfectly now, though it is not sure as to what was it that was causing the problem.

static BOOL RcrsvRegDel( HKEY hKey, LPTSTR lpszSub, DWORD dwOpenFlags )
{
    BOOL    bRet = TRUE ;
    LONG    lRet ;
    DWORD   dwSize = MAX_PATH ;
    TCHAR   szName[MAX_PATH] ;
    HKEY    hKeySub = NULL ;
    HRESULT hr = NULL ;
    HANDLE  hProcess = NULL ;
    HANDLE  hToken = NULL ;

    do{
        bRet = SetPrivilege( SE_BACKUP_NAME, TRUE ) ;
        if( bRet == FALSE )
        {
            bRet = FALSE ;
            break ;
        }

        lRet = RegOpenKeyEx( hKey, lpszSub, 0, dwOpenFlags, &hKeySub ) ;
        if( lRet != ERROR_SUCCESS )
        {
            bRet = FALSE ;
            break ;
        }

        while( ERROR_NO_MORE_ITEMS != (lRet = RegEnumKeyEx(hKeySub, 0, szName, &dwSize, NULL, 
            NULL, NULL, NULL)) )
            if( !RcrsvRegDel(hKeySub, szName, dwOpenFlags) ) 
            {
                bRet = FALSE ;
                break ;
            }

        lRet = RegDeleteKey( hKey, lpszSub ) ;
        printf("RegDelKey:: %S :: lRet = %ld\n", lpszSub, lRet) ;
        if( lRet != ERROR_SUCCESS )
        {
            bRet = FALSE ;
            break ;
        }

        if( hKeySub != NULL )
        {
            RegCloseKey(hKeySub) ;
            hKeySub = NULL ;
        }
    }while(0) ;
    return bRet ;
}

static BOOL SetPrivilege( LPCTSTR lpszPrivilege, BOOL bEnablePrivilege ) 
{
    LUID    luid ;
    BOOL    bRet = TRUE ;
    HANDLE  hToken = NULL ;
    HANDLE  hProcess = NULL ;
    TOKEN_PRIVILEGES tp ;

    do{
        hProcess = GetCurrentProcess() ;
        if( 0 == OpenProcessToken(hProcess, TOKEN_ADJUST_PRIVILEGES, &hToken) )
        {
            bRet = FALSE ;
            break ;
        }

        if( !LookupPrivilegeValue(NULL, lpszPrivilege, &luid) )
        {
            bRet = FALSE ;
            break ;
        }

        tp.PrivilegeCount = 1 ;
        tp.Privileges[0].Luid = luid ;

        if( bEnablePrivilege )
            tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED ;
        else
            tp.Privileges[0].Attributes = 0 ;

        if( !AdjustTokenPrivileges(hToken, FALSE, &tp, sizeof(TOKEN_PRIVILEGES), (PTOKEN_PRIVILEGES)NULL, 
            (PDWORD)NULL) )
        {
            bRet = FALSE ;
            break ;
        }

        if( ERROR_NOT_ALL_ASSIGNED == GetLastError() )
        {
            bRet = FALSE ;
            break ;
        }
    }while(0) ;
    if( hToken != NULL ) CloseHandle( hToken ) ;
    return bRet ;
}