Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

Reading registry error

Posted on 2006-07-13
7
Medium Priority
?
903 Views
Last Modified: 2008-01-09
Hi,

I tried to read the Autorun CD setting and found a function like this :

function IsCdAutoRunOn : bool;
var
  reg: TRegistry;
  AutoRunSetting : integer;
begin
  reg := TRegistry.Create;
  reg.RootKey := HKEY_CURRENT_USER;
  reg.OpenKey(
    'Software\Microsoft\Windows\CurrentVersion\Policies\Explorer',
              false);
  reg.ReadBinaryData('NoDriveTypeAutoRun',
                     AutoRunSetting ,
                     sizeof(AutoRunSetting));
  reg.CloseKey;
  reg.free;
  result :=  not ((AutoRunSetting and (1 shl 5)) <> 0);
end;

I got it from :

http://bdn.borland.com/article/0,1410,16175,00.html

When I run it, I got error :

... raised exception class ERegistryException with message 'Invalid data type for 'NoDriveTypeAutoRun'' ...

How to fix that ?

And why the code in the Borland code example has a bug like that ??? Or do I miss something here ???

Please help.

Thanks,

0
Comment
Question by:db2trade
  • 4
5 Comments
 
LVL 26

Accepted Solution

by:
Russell Libby earned 500 total points
ID: 17103844
Its stored as a DWORD value (integer). Try the following:

function IsCdAutoRunOn : bool;
var
  reg: TRegistry;
  AutoRunSetting : integer;
begin
  reg := TRegistry.Create;
  reg.RootKey := HKEY_CURRENT_USER;
  reg.OpenKey(
    'Software\Microsoft\Windows\CurrentVersion\Policies\Explorer',
              false);
  AutoRunSetting:=reg.ReadInteger('NoDriveTypeAutoRun');
  reg.CloseKey;
  reg.free;
  result :=  not ((AutoRunSetting and (1 shl 5)) <> 0);
end;

Regards,
Russell
0
 
LVL 26

Expert Comment

by:Russell Libby
ID: 17103881

And I have no idea why they would they would post it as such. The MS Technet lists this value as a DWORD, and the delphi code for ReadBinaryData performs the following checks:

  if ((RegData = rdBinary) or (RegData = rdUnknown)) and (Result <= BufSize) then
      GetData(Name, @Buffer, Result, RegData)
    else ReadError(Name);

which is going to fail if the data is a DWORD type, which it is.

Russell

0
 
LVL 1

Author Comment

by:db2trade
ID: 17103933
Yeah, I changed it to use ReadInteger and got it working. But the strange thing is, it does not work to set/unset Autorun CD !

I just really dont understand.
0
 
LVL 26

Expert Comment

by:Russell Libby
ID: 17104030

You never mentioned attempting to set the new state (a whole different question). Please show the code that you are using (specifically the value) for enabling/disabling the autorun for CD class drives.

Russell
0
 
LVL 26

Expert Comment

by:Russell Libby
ID: 17104114
Never mind, all documentation indicates that the system needs to be restarted for the setting to take effect. Running a registry monitor check also confirms that this value is not read in during the drive inserted event.

Russell
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
Introduction I have seen many questions in this Delphi topic area where queries in threads are needed or suggested. I know bumped into a similar need. This article will address some of the concepts when dealing with a multithreaded delphi database…
Is your data getting by on basic protection measures? In today’s climate of debilitating malware and ransomware—like WannaCry—that may not be enough. You need to establish more than basics, like a recovery plan that protects both data and endpoints.…
When cloud platforms entered the scene, users and companies jumped on board to take advantage of the many benefits, like the ability to work and connect with company information from various locations. What many didn't foresee was the increased risk…
Suggested Courses

783 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question