Registry access after driver load??

Hi guys,
Please bear with me, very premitive question.

I have installed my file system filter driver in WindowsXP, i have the
field(REG_SZ) in the
registry as password. If this password is empty; driver doesn't load there
is an check added to avoid loading of driver without valid password.

I have the user application to write the new password into registry. But
am not able to see the changed password after

RegSetValueEx function.

Am unable to figure out the cause. Is it the registry access by the user
program is invalid, or writing unicode string (i tried this no success)

Any suggestion is appreciated. Thanks in advance

The part of the registry access & change code is copied below.

char szNewPassword[]="abcde";

Result = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
L"SYSTEM\\CurrentControlSet\\Services\\Mydriver ",
0,KEY_QUERY_VALUE,&hKey);

if( nResult == ERROR_SUCCESS )
{
int nMaxLen = 16;

RegQueryValueEx(hKey,
L"Password",
NULL,(LPDWORD)&lpType,(LPBYTE)szPassword,
(LPDWORD)&nMaxLen);

printf("Old password %S",szPassword);

nMaxLen=6;

RegSetValueEx(hKey,
L"NewPassword",
NULL,REG_SZ,(BYTE *)szNewPassword,
nMaxLen);

RegQueryValueEx(hKey,
L"Password",
NULL,(LPDWORD)&lpType,(LPBYTE)szChanged,
(LPDWORD)&nMaxLen);

printf(" %S",szChanged);
}

--
Steeve
Singapore

Yes this likely is because of unicode conversions.
Since you use wide strings as key names, your program
probably is compiled with UNICODE. But your password string is ascii.
Get a debugger, debug.

Good luck with filesystem drivers.
--pa


"Steeve" <> wrote in message
news:139079B1-2B7D-4BA5-98D4-...
> Hi guys,
> Please bear with me, very premitive question.
>
> I have installed my file system filter driver in WindowsXP, i have the
> field(REG_SZ) in the
> registry as password. If this password is empty; driver doesn't load there
> is an check added to avoid loading of driver without valid password.
>
> I have the user application to write the new password into registry. But
> am not able to see the changed password after
>
> RegSetValueEx function.
>
> Am unable to figure out the cause. Is it the registry access by the user
> program is invalid, or writing unicode string (i tried this no success)
>
> Any suggestion is appreciated. Thanks in advance
>
> The part of the registry access & change code is copied below.
>
> char szNewPassword[]="abcde";
>
> Result = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
> L"SYSTEM\\CurrentControlSet\\Services\\Mydriver ",
> 0,KEY_QUERY_VALUE,&hKey);
>
> if( nResult == ERROR_SUCCESS )
> {
> int nMaxLen = 16;
>
> RegQueryValueEx(hKey,
> L"Password",
> NULL,(LPDWORD)&lpType,(LPBYTE)szPassword,
> (LPDWORD)&nMaxLen);
>
> printf("Old password %S",szPassword);
>
> nMaxLen=6;
>
> RegSetValueEx(hKey,
> L"NewPassword",
> NULL,REG_SZ,(BYTE *)szNewPassword,
> nMaxLen);
>
> RegQueryValueEx(hKey,
> L"Password",
> NULL,(LPDWORD)&lpType,(LPBYTE)szChanged,
> (LPDWORD)&nMaxLen);
>
> printf(" %S",szChanged);
> }
>
> --
> Steeve
> Singapore

Steeve <> wrote:
>
>Please bear with me, very premitive question.

Yes, your snippet is a textbook example of the reason why you should check
the error return codes from APIs.

>Result = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
> L"SYSTEM\\CurrentControlSet\\Services\\Mydriver ",
> 0,KEY_QUERY_VALUE,&hKey);

Here, you are asking for permission to query values from the registry.
That's all you asked for, so that's all you get.

>if( nResult == ERROR_SUCCESS )
>{
> int nMaxLen = 16;
>
> RegQueryValueEx(hKey,
> L"Password",
> NULL,(LPDWORD)&lpType,(LPBYTE)szPassword,
> (LPDWORD)&nMaxLen);
>
> printf("Old password %S",szPassword);
>
> nMaxLen=6;
>
> RegSetValueEx(hKey,
> L"NewPassword",
> NULL,REG_SZ,(BYTE *)szNewPassword,
> nMaxLen);

Here you are trying to change the value. You didn't ask for permission to
change the value. This API fails, but since you don't check the error
codes, you don't realize it.

If you want to write the value, ask for KEY_READ|KEY_WRITE.
--
Tim Roberts,
Providenza & Boekelheide, Inc.