Windows Registry reading RegQueryValueEx Failure

Question

2.50/5 (2 votes)

See more:

I have created a registry entry and want to read it through C program.
But the RegQueryValueEx() function is failing and I am not seeing any error.
I directly get the command prompt.

Here is the code snippet:

C++

#define REG_KEY          TEXT("Software\\MyCompany\\XYZ")    // XYZ is also a key and 
                                                                has a default value 
                                                                REG_SZ in it

HKEY hKey;
LONG lResult;
DWORD BufferSize = MAX_PATH;
DWORD dwValue, dwSize = sizeof(dwValue);

	_tprintf( _T("\nInside delOEMInf.") );

         if((RegOpenKeyEx(HKEY_LOCAL_MACHINE, 
                                          REG_KEY,
                                          0,
                                          KEY_ALL_ACCESS,
                                          &hKey)) == ERROR_SUCCESS)
            {
                _tprintf( _T("\ RegOpenKeyEx  OPENED"));

		lResult = RegQueryValueEx(hKey, "", NULL, NULL, (LPBYTE)&dwValue, BufferSize);
                _tprintf( _T("\nRegQueryValueEx %d"), lResult);
                RegCloseKey( hKey);
	}

I get only the first printf "RegOpenKeyEx OPENED".
The second printf does not gets printed and I see directly the command prompt.
I am not abel to get the return value of regqueryvalueex().

What might be the issue and how to debug and resolve it?

Posted 22-Apr-12 20:04pm

rupeshkp728

Add a Solution

Comments

chandanadhikari 23-Apr-12 2:35am

may be the code does not have the permission to read from the registry.Please check if the key really exists in the registry. What does the command prompt say when it comes up ?

barneyman 23-Apr-12 21:49pm

DON'T open HKLM with ALL_ACCESS for reading - win7 will fail on you

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Jochen Arndt · Answer 1 · 2012-04-22T21:04:00

You are passing the address of a DWORD value as output buffer and the address MAX_PATH as pointer to the size parameter. But RegQueryValueEx requires the address of a buffer that can hold the data specified by the lpcpData parameter which must be passed as address of a DWORD to receive the data length read from the registry.

So you have an access violation and a buffer overrun.

A workin code would look like:

C++

char lpszBuffer[MAX_PATH];
DWORD dwSize = MAX_PATH;
RegQueryvalueEx(hKey, "", NULL, NULL, LPBYTE(lpszBuffer), &dwSize);

Pablo Aliskevicius · Answer 2 · 2012-04-22T20:49:00

From MSDN: http://msdn.microsoft.com/en-us/library/windows/desktop/ms724897(v=vs.85).aspx[^]

Return value
If the function succeeds, the return value is ERROR_SUCCESS.
If the function fails, the return value is a nonzero error code defined in Winerror.h. You can use the FormatMessage function with the FORMAT_MESSAGE_FROM_SYSTEM flag to get a generic description of the error.

ERROR_SUCCEESS is zero, so RegOpenKeyEx is apparently failing. Use FormatMessage, and you'll get a hint of the reason.

Hope this helps,
Pablo.

Windows Registry reading RegQueryValueEx Failure

2 solutions

Solution 2

Solution 1

Add your solution here

Preview 0